Sensi Quiz Flashcards
What organisms should be screened for vanc resistance?
S. aureus and Enterococcus spp
Which bug/drug combinations have ECVs for bacteria?
P. acnes and Vanc
Salmonella, Shigella flexneri and sonnei and Azithro
E. coli, K. pneumo, R. orthinolytica, E. cloacae and aerogenes and Colistin
N. gonnorrhoae and Azithro
intrinsic Cephalosporin resistance
Enterococcus
Listeria
Bacillus anthracis
resistant to ampicillin
HACEK (produce beta-lacatmase, Rx 3rd gen cephalosporin)
What isolates of Staph spp are tested for beta-lactamases?
MSSA and MS CoNS
intrinsic novobiocin resistance
Staph saprophyticus
(generally) sensitive to bactrim
Burkholderia cepacia
What specimen source restrictions are there for daptomycin testing?
No respiratory sources
Mechanism of action of echinocandins
inhibit 1-3 glucan sythase in glucan sythesis
Ampicillin susceptible
Synercid (Quin/Dalf) resistant
E. faecalis
Tiers of Beta-lactamases
AmpC (lowest)
ESBL (middle)
Carbapenemases (highest)
Orgs we report as ESBLs
Klebsiella pneumoniae
Klebsiella oxytoca
Proteus mirabilis
E. coli
resistant to macrolides and clindamycin
Eikenella
What drugs should NOT be reported for Salmonella isolates?
1st and 2nd gen cephalosporins and aminoglycosides
intrinsic metronidazole resistance
Actinomyces
Proprionibacterium
Lactobacillus
What are the CLSI methods to detect carbapenemases and which bugs can they be used on (per CLSI)?
MHT (Enterobacteriaceae)
Carba-NP (Enterobacteriaceae, P. aerug, Acinteo spp)
mCIM (Enterobacteriaceae)
(plus molecular assays for all groups as well)
no AST
Legionella
Cefoxitin sensitivity screening
Predicts methicillin resistance in Staphylococci
Mechanism of action of amphoterecin B
Targets ergosterols and inserts into membrane
What methods are used to test for high level aminoglycoside resistance?
Disk diffusion, broth microdilution, and agar dilution
intrinsic vancomycin resistance
Pediococcus (PYR-) Weisella Erysipelothrix Enterococcus casseliflavus Enterococcus gallinarium Lactobacillus Leuconostoc (PYR-)
Clostridum innocuum
Definition of extended spectrum beta-lactamase (ESBL)
Hydrolyze at least 1 oxy-imino-beta-lactam at a rate of > or = to 10% of that of benzylpenicillin and are inhibited by clavulanic acid
What must be added to test fosfomycin AST?
Glucose-6-phosphate, this is added to KB disk, but must be added for MIC method (why agar dilution is only approved method)
How ESBLs are detected in the lab
3 doubling dilution shift in MIC w/ clavulanic acid or >= 5mm change in zone diameter for KB testing
What is the acceptable “validation” to go to weekly AST QC?
20 or 30 days of consecutive testing of all appropriate QC strains, with no more than 1/20 or 3/30 out of range QCs
Which drugs have meningitis and non-meningitis breakpoints for S. penumo?
Penicillin amoxicillin Cefepime Cefotaxime Ceftriaxone
What organisms are tested for high level aminoglycoside resistance?
Enterococcus spp
intrinsic bactrim resistance
Pseudomonas aeruginosa Strep Groups (BAD) - S.. agalactiae (B) - S. pyogenes (A) - Enterococcus (D)
Ampicillin resistant
Synercid (Quin/Dalf) susceptible
E. faecium
How is beta-lacatmase detection in Staph spp performed
S. aureus and CoNS - cefinase test (red/pink=pos) from zone around cefoxitin disk
S. aureus can also do penn KB - sharp edge=pos, fuzzy edge=neg
Which bug/drug combination has the SDD category?
Cefepime and Enterobacteriaceae
What are appropriate methods to test for methicilin resistance in Staph species?
For S. aureus and S. lugdunensis = Oxacillin MIC or cefoxitin disk/MIC
CoNS = Cefoxitin disk or MIC as surrogate for oxacillin
S. pseudintermiedius = Oxacillin disk or MIC
Which drugs have different breakpoints for S. aureus and CoNS?
Oxacillin (also S. lugdunensis and S. pseudintermedius)
Vancomycin
Mechanism of action of azoles
inhibit 14-alpha demethlyase in ergosterol sythesis
intrinsic colistin resistance
Burkholderia
Serratia
Porphyromonas
Common orgs with chromosomal AmpC
(SPACE!) Serratia Proteus/Pseudomonas* Acinetobacter/Aeromonas Citrobacter* Enterobacter
(plus Provdiencia, Hafnia, Morganella…)
*not all species have chromosomal AmpC
How is a vanc resistance screen done?
On BHI agar with 6ug/ml vanc, resuspension is inoculated directly on to plate and examined for growth of at least 1 colony, if growth, follow with appropriate vanc MIC method
Classic test for ESBLs
Double disk synergy test (looks for keyhole structure - where clav. acid inhibits and there is no growth)
resistant to all Beta-lactams except imipenem
Campylobacter
What agents are tested for high level aminoglycoside resistance?
Genatmysin, Streptomycin
sensitive to colistin
Pseudomonas
AmpC producers should be reported as “R” to which Abx?
1st and 2nd gen cephalosporins, and the cefamycins
What drugs should be reported on Slamonella isolates?
Intestinal - Amp, Fluoroquinolone, Bactrim (SXT)
Extra-intestinal - Above plus third gen cephalosporin
What species should be tested for inducible clindamycin resistance?
Staph spp, S. pneumo, and B-heme strep spp that are R to erythro and S or I to clinda
