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86 Cards in this Set
- Front
- Back
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name the 7 genera we study |
lactobacillus corynebacterium arcanobacterium erysipelothrix listeria bacillus aerobic actinomycetes |
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name the 4 aerobic actinomycetes |
norcardia streptomyces rhodococcus actinomadura |
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where can lactobacillus often be found as a contaminant? |
urine cultures |
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colonial morphology of lactobacillus |
-grows well on most media -forms pinpoint colonies -often confused with Viridans strep |
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what type of hemolysis does lactobacillus have? |
95% alpha 5% gamma |
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where are corynebacterium found as NF? |
skin and mucous membranes |
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gram stain of corynebacterium? |
gram+ pleomorphic rods, palisading |
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when would NF such as corynebacterium be clinically significant? |
-when found in large numbers in pure culture -repeatedly isolated from a normally sterile site |
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is speciation of corynebacterium usually required? |
no |
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when is speciation of corynebacterium required? |
when the isolate is clinically significant (causing infection) |
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is susceptibility testing routinely performed on corynebacterium? |
no |
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what are the 4 most common clinically significant isolates of corynebacterium? |
C. diphtheriae C. jeikenium C. urealyticum C. ulcerans |
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what species is the only natural host of C. diphtheriae? |
humans |
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what type of disease is diphtheria? |
endotoxin mediated |
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what are the two forms of diphtheria? |
respiratory cutaneous |
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what is the mechanism of the respiratory disease? |
-pseudomembrane formation in the throat, leading to suffocation -cardiac failure |
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how is diphtheria treated? |
-anti-toxin -penicillin or erythromycin |
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what are the preferred laboratory specimens for C. diphtheriae? |
-nasopharyngeal swab -throat swab |
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what can be seen with loeffler's stain? |
metachromatic granules |
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what is loeffler's stain? |
simple stain with methylene blue |
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what media are used if C. Diphtheriae is suspected? |
selective and differential: cysteine-tellurite blood agar, modified tynsdale's agar, loeffler's media |
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how is identification as a true pathogen made for C. diphtheriae? |
demonstration of toxin production |
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what 4 tests are used to demonstrate toxin production with C. diphtheriae? |
-guinea pig lethality test -Elek test -tissue cell culture test -PCR to detect toxin gene |
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what is the Elek test for C. diphtheriae? |
immunodiffusion of antitoxin on tellurite media |
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what is observed in the tissue culture test for C. diphtheriae? |
CPE in the suspension only tube |
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when does C. Jeikenium usually cause infection? |
immunocompromised with IV catheters |
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what drugs is C. Jeikenium susceptible too? |
C Jeikenium is multi-drug resistant |
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what organ does C. urealyticum affect? |
kidney |
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what drugs is C. urealyticum susceptible to? |
multidrug resistant |
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what animal does C. ulcerans usually affect? |
cattle |
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what 3 species of Arcanobacterium are of human importance? |
A. haemolyticum A. pyogenes A. Bernadiae |
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what is unique about Listeria? |
it can survive in cold temperatures |
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what disease can listeria cause in neonates? |
Granulomatosis infantiseptica |
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what happens in late onset granulomatosis infantiseptica? |
-symptoms 2-3 weeks after birth -meningitis or meningoencephalitis |
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what is the white cell value for meningoencephalitis? |
6-12k white cells, 90-98% monocytes |
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what are the 2 virulence factors of listeria? |
listeriolysin O protein P60 |
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what organism is listeria often confused with? |
group B strep |
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what are listeria's motility patterns on wet prep and semisolid media? |
tumbling motility on wet prep umbrella shape on semisolid media |
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how is listeria's CAMP test different from group B strep? |
square head hemolysis |
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is antibiotic susceptibility testing performed for listeria? |
no |
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how is listeria monocytogenes treated? |
gold standard: ampicillin+ aminoglycoside |
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what are the animal hosts of erysipelothrix rhusiopathiae? |
pigs cattle horses sheep birds |
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what are the acceptable clinical specimens for erysipelothrix rhusiopathiae? |
skin biopsy blood culture |
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is susceptibility testing done on erysipelothrix rhusiopathiae? |
no |
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what drug can be used to treat erysipelothrix rhusiopathiae? |
penicillin |
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what drug is erysipelothrix rhusiopathiae resistant to? |
vancomycin (and strep lucanocstoc) |
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when is bacillus not considered a lab contaminant? |
-isolated from repeated cultures -isolated from an eye culture |
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when is speciation of bacillus necessary? |
when anthracis is suspected |
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what types of media does bacillus not grow on? |
MAC, CNA |
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what are the components of the spore stain? |
malachite green safranin |
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what are the 4 species of clinical importance? |
B. anthraces B. cereus B. subtilis B. Sterothermophilus |
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what QC is B. Subtilis used in? |
ethylene oxide sterilization QC |
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what QC is B. thermophilus used in? |
autoclave QC |
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what must be done for any culture positive for GPR? |
-report to the state lab immediately -work up to rule out B anthracis |
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what is the most common form of anthrax infection worldwide? |
cutaneous anthrax |
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what are the 3 toxins produced by B anthracis? |
lethal factor (LF) edema factor (EF) protective antigen (PA) |
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virulence factor (anthrax): PA +LF |
lethal activity |
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virulence factor (anthrax): PA+EF |
edema |
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virulence factor (anthrax): PA+EF+LF |
edema and tissue necrosis |
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what part of B. Anthacis's capsule makes it resistant to phagocytosis? |
poly-D-glutamic acid |
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what are the acceptable specimens to rule out B. anthracis? |
nasopharyngeal swab (inhalation) blood culture (inhalation) vesicle fluid/swab (cutaneous) |
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what test is specific for B. Anthracis? |
gamma phage lysis |
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what test shows that B. Anthracis is susceptible to penicillin? |
string of pearls test |
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what drugs can be used to treat B. Anthracis? |
penicillin ciprofloxacin |
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what two toxin mediated diseases can be caused by B. cereus? |
emetic toxin disease enterotoxin disease |
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what drugs can B cereus be resistant to? |
penicillins and cephalosporins |
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is susceptibility testing performed for B cereus? |
no |
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what drugs can be used to treat B cereus? |
clindamycin vancomycin chloramphenicol ciprofloxacin tetracycline |
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in what 3 ways do Actinomycetes resemble fungi? |
-slow growth (>10 days) -aerial hyphae -fungal disease (granulomas/mycetomas) |
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what is substrate or vegetative hyphal form? |
organism grows on and into the agar |
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what is fragmentation mycelium? |
organism forms long chains of bacilli that break up as it ages |
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what is farmer's lung? |
allergic reaction to the organism's cell wall |
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men are 3 times as likely to become infected with which genera of actinomycetes? |
Nocardia |
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which Nocardia sp causes >80% of infections in the US? |
N. Asteroides |
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what drugs are used to treat Nocardia? |
sulfonamides, esp bactrim |
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what media is used for Nocardia? |
Lowenstein-jensen agar |
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what characteristic smell does nocardia have? |
dirt-like odor |
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can N. Asteroides hemolyze amino acids? |
no |
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in the lysozyme test, why does Nocardia show good growth in both the test tube and control tube? |
Nocardia is lysozyme resistant |
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what drugs are used to treat rhodococcus equi? |
vancomycin erythromycin |
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how does rhodococcus appear on gram stain? |
diphtheroid |
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what other organism does rhodococcus look like? |
TB |
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what is the colonial morphology of rhodococcus equi? |
salmon-pink colonies |
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what sample is best for actinomadura? |
lesion aspirate with granules |
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how would a lesion aspirate of actinomadura be prepared? |
-wash to remove contaminating bacteria -crush in 10% KOH to preserve -gram stain, looking for filaments |
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how can nocardia and rhodococcus be distinguished? |
nocardia produces branching hyphae on tap water agar, rhodococcus does not |
