- May 2017
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www.tandfonline.com www.tandfonline.com
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Latex agglutination techniques, phenotypic reactions and antibiograms
tests
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chronic, recurrent or persistent sore throat, which is believed to respond poorly to penicillin in vivo.
symptom
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www.sciencedirect.com www.sciencedirect.com
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quite a rare condition and modern-day clinicians of various medical disciplines are frequently unaware of this organism and the severity of symptoms that it can cause
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link.springer.com link.springer.com
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leukotoxin, endotoxin, haemolysin, haemagglutinin and adhesin
toxins
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Gram-negative, non-spore-forming anaerobe, is a normal inhabitant of the alimentary tract of animals and humans
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www.annfammed.org www.annfammed.org
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unilateral neck swelling due to suppurative thrombophlebitis of the internal jugular vein and may lead to sepsis, pulmonary abscess, and death
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journal.frontiersin.org journal.frontiersin.org
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Vancomycin is effective against most Gram-positive cocci and bacilli
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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Growth Requirements of N. Gonorrhoeae
Growth requirements of n. gonorrhoeae
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www2a.cdc.gov www2a.cdc.gov
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Pharyngeal infectionMay be sole site of infection if oral-genital contact is the only exposureMost often asymptomatic,but symptoms, if present, may include pharyngitis, tonsillitis, fever,and cervical adenitis. Exudative pharyngitis is rare.
signs/symptoms cdc
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Microbiologyand PathologyoEtiologic agent is Neisseria gonorrhoeae.oGram-negative intracellular diplococcus, oxidase-positive, utilizes glucose, but not sucrose, maltose, or lactose. Infects mucus-secreting epithelial cells.oDivides by binary fission every 20-30 minutes.oN. gonorrhoeaeattachesto different types of mucus-secreting epithelial cells via a number of structures located on the surface of gonococci.oN. gonorrhoeaehas ability to alter these surface structures, which helps the organism evade an effective host response.oN. gonorrhoeaeemploys several mechanisms to disarm the complement system, which may result in a survival advantage in the humanhost.
gonorrhoeae pathogenesis
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Gram-negative intracellular diplococcus, oxidase-positive, utilizes glucose, but not sucrose, maltose, or lactose. In
tests
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Pharyngeal gonorrheais readily acquired by fellatio but less efficientlyacquired bycunnilingus.
how you can get it
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www.aafp.org www.aafp.org
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Oral cephalosporins are up to 90 percent effective, compared with 99 percent for intramuscular ceftriaxone (Rocephin
tx
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oropharyngeal erythema or exudates
signs/symptoms
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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persistent or recurrent tonsillitis
recurrent tonsillitis
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www.mayoclinic.org www.mayoclinic.org
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Group B streptococcus (strep) is a common bacterium often carried in your intestines or lower genital tract. Group B strep is usually harmless in adults. In newborns, however, it can cause a serious illness known as group B strep disease.
Commonly found in the GI tract and mouth
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www.cdc.gov www.cdc.gov
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penicillin
Treatment with penicillin
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www.consumerreports.org www.consumerreports.org
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Disease
General Guideline on how long antibiotics should be used/prescribed.
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www.drugs.com www.drugs.com
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250 to 500 mg orally 3 times a day for 7 to 10 days; alternatively, 500 to 875 mg orally twice a day may be administered
information on how long antibiotics are generally prescribed to patients.
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Annotators
URL
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www.phac-aspc.gc.ca www.phac-aspc.gc.ca
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SURVIVAL OUTSIDE HOST: The bacterium can survive on a dry surface for 3 days to 6.5 months (22). It has been found to survive in ice cream (18 days), raw and pasteurized milk at 15-37 ºC (96 hrs), room temperature butter (48 hrs), and neutralized butter (12-17 days) (17). GAS has been found to last several days in cold salads at room temperature (18).
survival outside host
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www.cdc.gov www.cdc.gov
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This is another picture of a blood agar plate with growth and hemolytic activity of group B streptococci (GBS) (on the left) and group A streptococci (GAS) (on the right). Note that the colonies of both bacteria appear about the same color and size, but the degree of hemolytic activity is very different. The group A Streptococcus has more hemolytic activity than the group B Streptococcus. Experienced microbiologist use these traits to identify the two types of bacteria.
We can use this test to differentiate between GBS and GAS
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am positive cocci in pairs and short
picture of Group B
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gulig.med.ufl.edu gulig.med.ufl.edu
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Viridans streptococci gram-positive cocci usually in chains, but not always. Notice that these cannot be differentiated from Streptococcus pyogenes by the Gram stain.
Viridans group strep photo. "Usually in chains, but not always."
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www.cdc.gov www.cdc.gov
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nucleic acid amplification tests (NAATs)
quickest test
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Gonococcal specimens should be subcultured from the selective primary medium to a noninhibitory medium, e.g., chocolate agar with 1% IsoVitaleX to obtain a pure culture of the specimen. If the subcultured specimen is not pure, serial subcultures of individual colonies must be performed until a pure culture is obtained. After 18 to 20 hrs. incubation, a heavy suspension of growth from the pure culture should be made in trypticase soy broth containing 20% (v/v) glycerol
how to get pure sample
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A presumptive identification of N. gonorrhoeae will be based on the following criteria: (i) growth of typical appearing colonies on a selective medium such as Thayer-Martin at 35oC to 36.5oC in 5% CO2, (ii) a positive oxidase test, and (iii) the observation of gram-negative, oxidase-positive diplococci in stained smears.
how to test for n. gonorrhoeae
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NAATs that have been demonstrated to detect commensal Neisseria species might have comparable low specificity when testing oropharyngeal specimens for N gonorrhoeae
naat low specificity for pharnygeal
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pharyngeal infections with N. gonorrhoeae are frequently asymptomatic
frequently asymptomatic
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Extensive clinical experience indicates that ceftriaxone is safe and effective for the treatment of uncomplicated gonorrhea at all anatomic sites, curing 99.2% of uncomplicated urogenital and anorectal and 98.9% of pharyngeal infections in clinical trials (
dosage and #s
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Limited data suggest that dual treatment with azithromycin might enhance treatment efficacy for pharyngeal infection when using oral cephalosporins (
tx
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Ceftriaxone treatment failures for pharyngeal infections have been reported in Australia
tx
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Detection of infection using Gram stain of endocervical, pharyngeal, and rectal specimens also is insufficient and is not recommended.
can't just use gram stain
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noculated directly and when the growth medium is promptly incubated in an increased CO2 environment
gonorrheae conditions
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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More than 90% of staphylococcal isolates now produce penicillinase
Penicillin resistance of staph
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cbm.msoe.edu cbm.msoe.edumwp20071
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Penicillin kills bacteria by inhibiting the proteins which cross-link peptidoglycans in the cell wall (Figure 8).•When a bacterium divides i
how penicillin works
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www.nejm.org www.nejm.org
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Two Cases of Invasive Vancomycin-Resistant Group B Streptococcus Infection
vancomycin resistance GBS
Tags
Annotators
URL
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jcm.asm.org jcm.asm.org
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Resistance of group B streptococcus (GBS) to antibiotics, particularly erythromycin and clindamycin, w
GBS resistance
Tags
Annotators
URL
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- Apr 2017
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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Overall mortality remains high (20% to 34% in larger series)
mortality
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Some resistance to er ythromycin, the agentof choice for penicillin-allergic patients with streptococ-cal phar yngitis, has been reported
Antibiotic resistance
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High-dose penicillin G remains the antibiotic ofchoice for treatment of GAS, with no resistancerecorded.
Antibiotic of choice
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Proteinases and other enzymes might con-tribute to tissue destruction
Virulence factor - tissue destruction
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Streptococcal toxic shock syndrome (STSS) canbe associated with invasive infections secondar y toGAS infection
Virulence factor - toxicity
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journal.frontiersin.org journal.frontiersin.org
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Stevens–Johnson syndrome
A reaction to a medication or an infection. Often, it begins with flu-like symptoms, followed by a painful red or purplish rash that spreads and blisters.
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Gram-positive infections
all of our organisms were gram-positive so this was a good first line treatment
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vancomycin creep
result of overuse of vanomycin. must be cautious to reduce chances adverse effects in the future from toxicity
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enterococci that became vancomycin resistant, mostly Enterococcus faecium
resistance
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effective against most Gram-positive cocci and bacilli with
antibiotic usefulness
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renal toxicity
present day side effect caustion
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vancomycin creep
Potential that "vancomycin creep" is method dependent
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S. aureus, there are only a handful of vancomycin-resistant strains
Vancomycin resistance found in S. aureus
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methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE) and amoxicillin-resistant enterococci
Main uses of Vancomycin = bacterias with resistance to other antibiotics, perhaps not usual first line of defense if organism isn't known
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Staphylococci failed to develop resistance to 05865
There have been a few strains that are found to be VISA or VRSA which are Staph that have developed a resistance to vancomycin. They are able to be treated by other drugs. https://www.cdc.gov/hai/organisms/visa_vrsa/visa_vrsa.html
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similar in weight
why is weight important?
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osteomyeliti
infection of the bone
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endocarditis
infection of the heart
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ith S. aureus, there are only a handful of vancomycin-resistant strains.
Vancomycin has been used for many years, but still has a low number of resistant S. aureus strains.
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Enterococcus faecium
This can live within the intestine and not have harmful effects, but it can also be dangerous and lead to neonatal meningitis or endocarditis. https://en.wikipedia.org/wiki/Enterococcus_faecium
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Thrombocytopenia
Decreased platelets in the blood.
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Mississippi Mud
Switching from picric acid percipitation to ion-exchange resin purified the coumpound and made it ready for clinical use. Source
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fast track approval
By definition, this occurs when there is potential in a drug that can effectively treat a serious ilness whos medical need is currently unmet (FDA).
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armamentarium
the medicines, equipment, and techniques available to a medical practitioner. (Merriam-Webster)
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MIC
Wikipedia: lowest concentration of a chemical that prevents visible growth of a bacterium
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vestibular and renal
Vestibular: Parts of the inner ear and brain that help control balance and eye movements Renal: Kidney
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APACHE scores
Acute Physiology and Chronic Health Evaluation
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osteomyelitis
Infection of the bone typically caused by S. aureus.
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Vancomycin-associated nephrotoxicity can still be seen, even in the presence of appropriate serum concentrations, especially when it is co-administered with aminoglycosides, amphotericin B, foscarnet, pentamidine ACE inhibitors, loop diuretics, cyclosporine, cyclophosphamide
Vancomycin is stated earlier in article to be more effective when used in combination therapy because the combination therapy acts faster than vancomycin alone. Downside of combination therapy is increased nephrotoxicity risk.
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it is likely remain effective as long as resistance to vancomycin remains controlled.
What are the best ways to control this resistance?
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open – labeled studies
A study in which both the researchers and the patient knows which drug the patient is given.
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bacteriostatic
Stops bacteria from reproducing, but does not necessarily kill them.
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vancomycin exposure after colonization as the strongest predictor of prolonged colonization
Allowed to grow better when there is less competition from vancomycin-susceptible bacteria?
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only a handful
There are 3 different kinds of Vancomycin-resistant S. aureus that vary in how resistant they are.
https://en.wikipedia.org/wiki/Vancomycin-resistant_Staphylococcus_aureus
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Neutropenia
Fewer neutrophils in the blood
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APACHE scores
Indicates severity of disease
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q6h
Every 6 hours
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many side effects including vestibular and renal, most likely due to impurities
Early side effects often correlated with impurities as opposed to antibiotic itself
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It has been speculated that exposure to oral vancomycin is an important contributor to propagation of VRE in the healthcare setting, as it drives prolonged colonization with VRE from a myriad of sources (36, 37).
Oral vancomycin may cause the development of VRE's which are "vancomycin-resistant enterococci" (Google Search).
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Vancomycin and the above mentioned compounds inhibit cell wall synthesis in its later stages thus affecting dividing bacteria.
This is how we discussed the effect of vancomycin on bacteria in lecture.
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Earlier on, vancomycin was associated with many side effects including vestibular and renal,
Maybe this is such an effective antibiotic due to its disuse over the last 50 years. The side effects of the earlier iterations of the drug kept doctors from prescribing it. Has this preserved its efficacy and limited bacterial resistance?
https://academic.oup.com/cid/article-lookup/doi/10.1086/491709
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Vancomycin resistance among enterococci is attributed to change in the d-alanyl-d-alanine portion of peptide precursor units, transmitted as Van genes, thus rendering it incapable of inhibiting peptidoglycan polymerase and transpeptidation reactions.
Mechanism bacteria use to resist vancomycin.
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Vancomycin is a tricyclic glycopeptide (Figure 1) that consists of seven membered peptide chains forming the tricyclic structure and attached disaccharide composed of vancosamine and glucose.
The structure could be imporant in how it is able to treat bacteria.
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led to attempts to treat such patients with higher doses of vancomycin
problems with treating too aggressively
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ototoxicity
damage to inner ear - can lead to hearing and balance problems
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“slow bactericidal”
slow acting- would need to start Vanc treatment asap
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red man” syndrome,
very itchy red rash on upper portion of body
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major use of vancomycin today is for infections caused by methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE) and amoxicillin-resistant enterococci. In its oral form, vancomycin is used to treat diarrhea caused by Clsotridium difficile.
Vancomycin can be used to tackle MRSA (Methicillin Resistant Staph Aureus) and MRSE (Methicillin Resistant Staph Epidermidis)
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The subsequent emergence of vancomycin resistance among enterococci in the mid-1980s and failure of such patients even if they had enterococci with vancomycin-intermediate susceptibility was described, resulting in vancomycin losing it omnipotence for all gram-positive cocci (12). The appearance of S. aureus strains with intermediate susceptibility to vancomycin (VISA) and vancomycin-resistant S. aureus (VRSA) (12–14) and vancomycin-resistant S. epidermidis (VRSE) (15, 16), brought an end to the hitherto hegemony of vancomycin in the Gram-positive coccal arena. Fortunately, the occurrence of these difficult to treat Staphylococci remains rare.
intermediate resistance
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oral
many different forms of the drug, ORAL
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toxicity
Renal (kidney) toxicity if given higher dose
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inhibit cell wall synthesis in its later stages thus affecting dividing bacteria
If cell wall can't grow, cells can't divide
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Vancomycin remains the first-line agent for methicillin-resistant coagulase-negative and coagulase-positive staphylococcal infections
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Vancomycin is effective against most Gram-positive cocci and bacilli with the exception of rare organisms as well as enterococci that became vancomycin resistant, mostly Enterococcus faecium
Vancomycin is effective on gram positive bacteria that have a thick peptidoglycan later.
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Review ARTICLE
This is a reputable open source journal and the authors are at a reputable academic institution.
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similar molecular weight
I wonder why the author thinks the molecular weight matters to the story here. Is there a clinical reason that the molecular weight would matter other than how the drug is prepared?
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compared to β-lactams, this slow activity is reflected also in the worse clinical outcomes of cases of MSSA bacteremia and pneumonia treated with vancomycin
Why would slow activity be an issue for the patient?
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While vancomycin is bactericidal against all susceptible Gram-positive pathogens it exerts only bacteriostatic activity against enterococci and needs to be combined with another agent, usually an aminoglycoside, to achieve bactericidal activity.
I am really interested in how the same compound could have differential effects on different organisms.
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bactericidal
kills bacteria
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MIC
Minimum Inhibitory Concentration (from Wikipedia with PICs)
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only a handful
I wish there were numbers here to back this up....does a handful mean less than 5?
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trough serum levels
what does this mean? I looked it up (wikipedia) and it is the dip in levels of Vanco in the blood. Dosing in Vanco treatment is timed to coincide with the dip so that the dosage stays high in the blood
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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The overall mortality rate was 15%, with no significant difference between groups.
MRSA mortality rate
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Annotators
URL
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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Antibiotic susceptibilities of GBS isolates
Vancomycin effectivness
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Antimicrobial Susceptibilities of Group B Streptococcus Isolates from Prenatal Screening Samples
vancomycin and group b strep
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rarediseases.org rarediseases.org
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Group A Streptococci
Most common cause of NF
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academic.oup.com academic.oup.com
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Streptococcus Penicillinplusclindamycin 2–4 million units every 4–6 h IV (adult)600–900 mg every 8 h IV 60 000–100 000 units/kg/dose every 6 h IV10–13 mg/kg/dose every 8 h IV Vancomycin, linezolid, quinupristin/dalfopristin, daptomycin Staphylococcus aureus Nafcillin 1–2 g every 4 h IV 50 mg/kg/dose every 6 h IV Vancomycin, linezolid, quinupristin/dalfopristin, daptomycin Oxacillin 1–2 g every 4 h IV 50 mg/kg/dose every 6 h IV Cefazolin 1 g every 8 h IV 33 mg/kg/dose every 8 h IV Vancomycin (for resistant strains) 30 mg/kg/d in 2 divided doses IV 15 mg/kg/dose every 6 h IV
antibiotics Information
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www.phac-aspc.gc.ca www.phac-aspc.gc.ca
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MODE OF TRANSMISSION: Transmission via respiratory droplets, hand contact with nasal discharge and skin contact with impetigo lesions are the most important modes of transmission (5, 9, 13). The pathogen can be found in its carrier state in the anus, vagina, skin and pharynx and contact with these surfaces can spread the infection (5, 14, 15) The bacterium can be spread to cattle and then back to humans through raw milk as well as through contaminated food sources (salads, milk, eggs); however, cattle do not contract the disease (16-18). Necrotizing fasciitis is usually because of contamination of skin lesions or wounds with the infectious agent (12).
transmission + usual route of entry for nec fasc, GAS
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www.uwyo.edu www.uwyo.edu
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Staphylococcus and Streptococcus species:
lab tests - MSA, blood agar, catalase, coagulase S. aureus, S. pyogenes
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whereas Streptococcus and Enterococcus spp. are catalase negative.
Testing results
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whereas Streptococcus species and many other organisms are inhibited by high concentrations of NaCl.
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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Numerous epidemiological studies have identified high rates of invasive S. pyogenes infection in men rather than women, a pattern that can be observed for many other invasive bacterial infections and one that is not fully understood. Age-specific incidence rates show a typical J-shaped distribution, with highest rates in the elderly, followed by infants. Assessment of rates of disease according to patient ethnicity show generally higher rates of disease in individuals of non-white European descent. These observations have been made in a diverse range of populations, including indigenous populations of Australia, New Zealand, the Pacific Islands, and circumpolar regions of the northern hemisphere. The reasons behind these excesses in risk are poorly understood and could reflect differential access to healthcare or general living conditions—but could also encompass some genetic predisposing factors.
demographic risk factors for GAS
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Carriage and transmission of group A streptococci
transmission
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Numerous epidemiological studies have identified high rates of invasive S. pyogenes infection in men rather than women, a pattern that can be observed for many other invasive bacterial infections and one that is not fully understood. Age-specific incidence rates show a typical J-shaped distribution, with highest rates in the elderly, followed by infants. Assessment of rates of disease according to patient ethnicity show generally higher rates of disease in individuals of non-white European descent. These observations have been made in a diverse range of populations, including indigenous populations of Australia, New Zealand, the Pacific Islands, and circumpolar regions of the northern hemisphere. The reasons behind these excesses in risk are poorly understood and could reflect differential access to healthcare or general living conditions—but could also encompass some genetic predisposing factors. Future studies will assist in identifying potential strategies to mitigate this risk.
men more than women
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www.sciencedirect.com www.sciencedirect.com
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TABLE III. MicrobiologyAerobicGram-positive cocciStaphylococcus aureus27MRSA3Coagulase-negative Staphylococcus40 (incl S epidermidis, S hemolyticus)StreptococcusBeta-hemolytic70Group A40Group B17 (incl S agalactiae, 1)Group D6 (non-Enterococcus)Group F5Group G2Alpha-hemolytic/S viridans31
Table of prevalence of S. aureus, Group A strep, Group B strep, and S. viridans
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www.sciencedirect.com www.sciencedirect.com
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ble 2. Pathogens associated with necrotizing fasciiti
prevalence
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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1 week after moderate trauma.
step b rate of onset
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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group B streptococci (Streptococcus agalactiae) have been reported to cause necrotizing fasciitis in only 4 instances (2 involving neonates) over the past 4 decades
prevalence
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Annotators
URL
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books.google.com books.google.com
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International Journal of Orthodontia and Oral Surgery, Volume 6
Viridian's does not produce gas
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www.cdc.gov www.cdc.gov
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Bile-esculin Tes
bile esulin test
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www.asp.mednet.ucla.edu www.asp.mednet.ucla.edu
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Vancomycin
treatment
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emedicine.medscape.com emedicine.medscape.com
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Antimicrobial therapy should continue for 48-72h after fever resolves
Nec Fac treatment time line
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www.antimicrobe.org www.antimicrobe.org
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Necrotizing Fasciitis (Streptococcal Gangrene): GAS necrotizing fasciitis is a rapidly progressing infection of the deep subcutaneous tissues and fascia with extensive and rapidly spreading necrosis. Infections often spare the skin, but 50% of patients may have associated myonecrosis. Necrotizing fasciitis is often associated with severe systemic involvement and an associated high mortality rate (7,80,87). As in other invasive streptococcal and staphylococcal skin infections, the site of inoculation is usually at area of minor trauma or the skin lesions of varicella. Like streptococcal bacteremia, there is a clear association between varicella and necrotizing fasciitis. Varicella is characterized by full-thickness dermal lesions that may induce selective immunosuppression to GAS, though this has not been substantiated (7). Necrotizing fasciitis caused by mixed infections, involving both aerobic and anaerobic Gram negative bacteria, is more likely to occur in the abdominal wall, following abdominal surgery or in diabetic patients.
Nec Fasc. GAS
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Early and aggressive surgical debridement of the site of infection as well as appropriate antimicrobial therapy is required. Due to the "inoculum effect," penicillin may be less effective in the treatment of necrotizing fasciitis (83). Appropriate antibiotics include nafcillin and clindamycin (7,83).
antibiotic treatment for nec fas.
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Puerperal Sepsis: Puerperal sepsis occurs during pregnancy or during an abortion, when group A streptococcus colonizing the patient invades the endometrium and surrounding structures as well as the lymphatics and bloodstream. Endometritis and septicemia result and can be complicated by pelvic cellulitis, thrombophlebitis, peritonitis, or pelvic abscess. Therapy consists of aggressive surgical exploration and parenterally administered penicillin or clindamycin (see section on myositis/myonecrosis). Patients allergic to penicillin can be treated with a first generation cephalosporin, clindamycin, or vancomycin (8).
treatment of GAS infection
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URL
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antibiotic
antibiotics for GAS
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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Antibiotic-killing kinetics of group B streptococci.
Kinetics of vancomysin--> Purchased to see that it is resistant 4hr group a 20-24 hrs group b
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URL
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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S. pyogenes isolates showed complete sensitivity to teicoplanin, vancomycin, and levofloxacin.
Vancomycin
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en.wikipedia.org en.wikipedia.org
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only five are known to commonly cause disease in immune-competent human beings: Group A, Group B, both members of Group D, and two groups that lack the Lancefield carbohydrate antigen: Streptococcus pneumoniae and Viridans streptococci.[5]
differentiate GAS and GBS from viridans group strep
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en.wikipedia.org en.wikipedia.org
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If the mixture produces bubbles or froth, the organism is said to be 'catalase-positive'
catalase test
Tags
Annotators
URL
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en.wikipedia.org en.wikipedia.org
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The reagent is a dark-blue to maroon color when oxidized, and colorless when reduced.
oxidase test
Tags
Annotators
URL
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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Dose-dependentinhibitionofgrowthofS43/192/
penicillin mechanism
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www.news-medical.net www.news-medical.net
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Penicillins and other antibiotics in the beta-lactam family contain a characteristic four-membered beta-lactam ring. Penicillin kills bacteria through binding of the beta-lactam ring to DD-transpeptidase, inhibiting its cross-linking activity and preventing new cell wall formation.
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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s: acetoin production from glucose (positive Vogues-Proskauer reaction), arginine, and sorbitol. These are very useful for the differentiation of this group from oth
biochem
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Epidemiology of resistance in children.
antibiotic resistance
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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The ability to invade HUVEC was exhibited by selected strains of S. gordonii, S. sanguis, S. mutans, S. mitis, and S. oralis but only weakly by S. salivarius. Comparison of isogenic pairs of S. gordonii revealed a requirement for several surfa
attachement
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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S mutans and S sanguis (involved in dental caries), S mitis (associated with bacteremia, meningitis, periodontal disease and pneumonia), and “S milleri” (associated with suppurative infections in children and adults).
assciated diseases
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Annotators
URL
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www.yourgenome.org www.yourgenome.org
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Symptoms include: tiredness weakness fever weight loss respiratory problems problems with heart function in cases where endocarditis occurs.
symptoms of viridan
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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How antibiotics kill bacteria: from targets to networks
How penicillin works
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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BS strains resistant to penicillin were found to contain spontaneous mutations that conferred amino-acid substitutions
resistance
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www.cdc.gov www.cdc.gov
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Lancefield group B antigen
Test
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Laboratory Photo Examples
list of tests to identify Group B Strep with pictures.
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catalog.hardydiagnostics.com catalog.hardydiagnostics.com
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FORMULA Ingredients per liter of deionized water:* Pancreatic Digest of Casein 15.0gm Peptic Digest of Soybean Meal 5.0gm Sodium Chloride 5.0gm Sheep Blood 50.0ml Agar 12.0gm Final pH 7.3 +/- 0.2 at 25ºC.
sheep blood agar - components (from Hardy Diagnostics) and pH
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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SUPPORT PROTOCOLS FOR DIFFERENTIAL IDENTIFICATION OF S. PYOGENES (GAS) (adapted from microbelibrary.org)
Gram stain, catalase assay, & oxidase assay
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NOTE: All steps should be performed using sterile technique. GAS will remain viable on plates for only 5–7 days after streaking if stored at room temperature. GAS does not survive at 4°C.
temperature requirements
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is a facultative anaerobe and is grown at 37°C in either ambient air or in 5–10% CO2. Like all streptococci, GAS is both catalase and oxidase negative. GAS lacks the necessary enzymes for a functional TCA cycle and oxidative-cytochromes for electron transport; therefore, relies completely on fermentation of sugars for growth and energy production. It is a member of the lactic acid bacteria and is homofermentative for lactic acid production from glucose fermentation. Specific components of a rich growth medium for GAS include neo peptone extracts, glucose as carbon source, and a complex mixture of nutrients from beef heart infusion as first described by Todd & Hewitt (Todd and Hewitt, 1932). GAS is considered a multiple amino acid auxotroph requiring nearly all amino acids to be present in its growth media. A Chemically Defined Medium has been developed for GAS containing all of the necessary amino acids for GAS growth (van de Rijn, 1980).
Lab tests, microbe metabolism
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GAS grows best on complex “rich” medium such as Trypticase Soy Agar (TSA) supplemented with 5% Sheep Blood
Ideal growth
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Adjust the pH to 7.5.
pH
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Optimal growth of GAS is seen in 5% CO2; however, GAS will also grow in ambient air albeit a little slow.
other growing conditions
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S. pyogenes is a facultative anaerobe and is grown at 37°C in either ambient air or in 5–10% CO2
Growth conditions
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GAS is considered a multiple amino acid auxotroph requiring nearly all amino acids to be present in its growth media. A Chemically Defined Medium has been developed for GAS containing all of the necessary amino acids for GAS growth
growth requirements for GAS
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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For presumptive identification of S. pyogenes, cultures should be tested for bacitracin susceptibility and PYR activity (as described below). A definitive diagnosis should include a positive Lancefield group A antigen test. Negative results can be confirmed after a total culture time of 48 hours.
IMPORTANT!!! Include under Question 12 (Other tests):
- Increased bacitracin sensitivity (bacitracin = antibiotic) 2.PYR activity (tests for enzyme that produces red color under test conditions and is specific to S. pyogenes)
- Lancefield group A antigen test (Definitive diagnosis)
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To identify S. pyogenes in clinical samples, blood agar plates are screened for the presence of β-hemolytic colonies. The typical appearance of S. pyogenes colonies after 24 hours of incubation at 35-37°C is dome-shaped with a smooth or moist surface and clear margins. They display a white-greyish color and have a diameter of > 0.5 mm, and are surrounded by a zone of β-hemolysis that is often two to four times as large as the colony diameter. Microscopically, S. pyogenes appears as Gram-positive cocci, arranged in chains (Figure 1).
Colony morphology
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catalog.hardydiagnostics.com catalog.hardydiagnostics.com
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The ability of bacterial species to hydrolyze the compound hippurate was classically tested using ferric chloride indicator to detect benzoic acid, the first byproduct in the hippurate hydrolysis pathway. However, a 2½ hour rapid method as opposed to the 48 hour classical method for detecting hippurate hydrolysis has since been developed. The rapid test employs ninhydrin as the indicator, which detects glycine, the second byproduct of hippurate hydrolysis. The rapid hippurate hydrolysis test has been shown to be as specific and as sensitive as the classical method that detects the benzoic acid byproduct. (4,5,8,9)
Hippurate test
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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Superantigens are potent immunostimulators that cause clonal proliferation of T cells and watershed production of pro-inflammatory cytokines that mediate shock and organ failure.
Superantigens cause STSS by inducing T-cell proliferation and production of proinflammatory cytokines.
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URL
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GBS hyaluronidase degrades pro-inflammatory hyaluronan (HA) fragments to disaccharides•HA disaccharides block TLR2/4 signaling by both HA fragments and TLR2/4 agonists•Hyaluronidases secreted by Gram-positive pathogens promote immune evasion•HA disaccharides and GBS hyaluronidase inhibit inflammation in a lung injury model
Immune evasion
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microbewiki.kenyon.edu microbewiki.kenyon.edu
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Numerous phages are known to carry determinants that increase virulence to the bacterial host. These factors have been predominantly secreted toxins, such as the streptococcal erythrogenic toxin, staphylococcal enterotoxin A, diphtheria toxin, and cholera toxin (10). Other phage-encoded virulence determinants include extracellular enzymes such as staphylokinase and streptococcal hyaluronidase, enzymes that alter the antigenic properties of the host strain, and outer membrane proteins that increases serum resistance (10). It is likely that Pb1A and Pb1B bind platelets directly, although the mechanism by which PblA and PblB mediate platelet binding by S. mitis has not been illustrated. Thus, the encoding of PblA and PblB by lysogenic SM1 may represent a class of phage-mediated virulence determinants (10).
virulence
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en.wikipedia.org en.wikipedia.org
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three biochemical reactions:
biochemical test
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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The attachment of S. pyogenes to the pharyngeal and skin epithelial cell surfaces represents a critical first step in establishing such infections.
Point of infection, attachment point
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human infections that involve the upper respiratory tract and skin, including acute pharyngitis and impetigo.
generally targets the respiratory tract and skin. note this for the case. Patient's point of entry was through a skin break.
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www.health.ny.gov www.health.ny.gov
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Occasionally, however, these bacteria can cause much more severe and even life threatening diseases such as necrotizing fasciitis (occasionally described as "the flesh-eating bacteria") and streptococcal toxic shock syndrome (STSS).
Again, group A can cause the symptoms seen in the patient.
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www.cdc.gov www.cdc.gov
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The skin may be warm with red or purplish areas of swelling that spread rapidly. There may be ulcers, blisters, or black spots on the skin.
symptoms
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jcm.asm.org jcm.asm.org
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Briefly, the organism was plated on blood Mueller-Hinton agar and incubated at 35°C in ambient air (preferred), or with CO2 if required for growth, for 20 to 24 h.
Culture growth requirements
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All 50 strains were susceptible to vancomycin
effective antibiotic
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based on alpha-hemolysis, gram-positive reaction, coccus morphology in chains, negative catalase test, and exclusions of pneumococci and enterococci by routine biochemical tests (optochin test, bile solubility, and PYR [N,N-dimethylaminocinnamaldehyde] test).
Identification of VGS in lab
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nutritionally fastidious and mainly alpha-hemolytic on sheep blood agar
Lab media
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Sequencing analysis of the 16S rRNA gene has become an essential part of bacterial taxonomy
Additional lab tests
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www.cdc.gov www.cdc.gov
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Types of Infection and Symptoms
Signs/symptoms
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These skin infections may also be accompanied by a fever
fever
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Red Swollen or painful Warm to the touch Full of pus or other drainage
similar to the case
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invasive group B strep infection (infections where the bacteria have entered a part of the body that is normally not exposed to bacteria)
Transmission: bacterial exposure to area ex: cut on the hand like case #1 patient
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Spread to Others
Source of invasive GBS is unknown when it is not from pregnant women. Mode of transmission=? Host=humans
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www.cdc.gov www.cdc.gov
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chromogenic pigments for the detection of beta-hemolytic GBS using color detection
beta-hemolytic?--> breakdown of red blood cells,
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TransVag broth may be supplemented with 5% defibrinated sheep blood to increase the recovery of GBS
media
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www.merckmanuals.com www.merckmanuals.com
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Rapid antigen tests
test
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viridans streptococci are often susceptible to penicillin G and other β-lactams. Resistance is growing, and therapy for such strains should be dictated by results of in vitro susceptibility tests.
use these antibiotics
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Necrotizing fasciitis should be treated in an ICU. Extensive (sometimes repeated) surgical debridement is required. A recommended initial antibiotic regimen is a β-lactam (often a broad-spectrum drug until etiology is confirmed by culture) plus clindamycin. Although streptococci remain susceptible to β-lactam antibiotics, animal studies show that penicillin is not always effective against a large bacterial inoculum because the streptococci are not rapidly growing and lack penicillin-binding proteins, which are the target of penicillin activity.
treatment - general
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www.antimicrobe.org www.antimicrobe.org
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VGS are presumed to be uniformly susceptible to penicillin
Effective antibiotic: penicillin
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Annotators
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microbeonline.com microbeonline.com
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Catalase mediates the breakdown of hydrogen peroxide H2O2 into oxygen and water.
Catalase test can be used to see if a bacteria breakdown hydrogen peroxide
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www.pnas.org www.pnas.org
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TheseresultsindicatethatthehyaluronicacidcapsuleofmucoidGASprotectstheorganismfromphagocytosisandenhancesvirulence.
HA also part of immune evasion
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Mproteinhasbeenconsideredtobethemajorsurfacecomponentrespon-sibleforresistanceofGAStophagocytosis(12)
immune evasion-virulence factor
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OccasionalstrainsofGASisolatedfromclinicalsourcesgrowaslarge,spreading,wetcoloniesonsolidmedia;
colony morphology
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Annotators
URL
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www.bacteriainphotos.com www.bacteriainphotos.com
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grape-like clusters when viewed through a microscope, and has round, usually golden-yellow colonies
Morphology of the colonies
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www.phac-aspc.gc.ca www.phac-aspc.gc.ca
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Humans (neonates, elderly, immunocompromised, diabetic, alcoholic, and stroke and cancer patients have a higher risk of infection), cattle (mastitis), dogs, cats, rabbits, horses, guinea pigs, and goats have been shown to contain the infectious agent
GBS reservoir
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textbookofbacteriology.net textbookofbacteriology.net
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Gram-positive
its stains purple
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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tetracycline, to which 26 strains were resistant
resistant to this
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www.dph.illinois.gov www.dph.illinois.gov
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chronic conditions (diabetes, cancer), compromised immune systems (receiving chemotherapy, autoimmune disorders or HIV infection) or open wounds or sores that allow the bacteria to enter the tissue.
factors that increase a persons risk of contracting the virus
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"Strep throat," – swollen tonsils possible covered with a grayish-white film, swollen lymph nodes, and fever with or without chills, painful swallowing and headache. Impetigo - mild skin infection accompanied by open, draining sores and other general symptoms of GAS infection such as fever, swollen lymph nodes and a sore throat. Scarlet fever - characterized by a fever, sore throat, red sandpaper-like rash and a red "strawberry" tongue. It is caused by several different strains of the streptococcal bacteria, all of which produce a toxin that cause the characteristic red rash.
some of the signs and symptoms
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www.medicinenet.com www.medicinenet.com
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Adults who develop invasive GBS infection may develop
Sepsis, soft tissue infection, bone infection, pneumonia, UTI, meningitis
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The exact source of the infection in nonpregnant adults is often not determined
The source of GBS in for non pregnant people is not yet determined.
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diabetes, cardiovascular disease, obesity, and cancer.
Vulnerable Populations: Neonates and those with diabetes, cardiovascular disease, obesity, and cancer.
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Group B strep (GBS) are bacteria found normally in the intestine, vagina, and rectal area in about 25% of all healthy adult and pregnant women.
Reservoir "GBS can exists in most women without causing any symptoms"
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emedicine.medscape.com emedicine.medscape.com
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culture of a single throat swab on a blood agar plate yields a sensitivity of 90-95% for the detection of group A streptococci (GAS) in the pharynx
throat culture swab
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Most laboratories inoculate throat swabs on 5% sheep blood agar containing trimethoprim-sulfamethoxazole
Possible swabs
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In patients with acute pharyngitis, group A beta-hemolytic streptococcal infection should be ruled out.
Clear distinction
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antibodies for the detection of group A carbohydrate antigen.
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frozen section biopsy
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www.cdc.gov www.cdc.gov
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Bartonella henselae
Bacterial
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scratch
Mode of Transmission: Blood (through scratch)
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www.cdc.gov www.cdc.gov
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Typhoidal
General non-specific tularemia, without localized symptoms.
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Pneumonic
Tularemia of the lungs. Most serious form. Comes from breathing in aerosolized infectious material.
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Oropharyngeal
Tularemia of the throat
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signssymptoms.org signssymptoms.org
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Common symptoms are cellulites, swelling, redness, tenderness & discharge at the infected site, regional lymphadenopathy, chills, fever, high level of leukocyte & neutrophil.
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