Unit IV Flashcards
Lysozyme targets the ____ of bacteria
peptidoglycan layer
Capsule are primarily made of
polysaccharides
Permeability fo cytoplasmic membrane
selective
impermeable to charged substances even H+
Inoculum
Lag phase
Tetanus toxin and botulinum toxins are ___ dependent endopeptidases
Zinc-dependents
Why don’t gram positive bacteria grow in maconkey
inhibited by crystal violet and bile salts
Bacteria that ferment in maconkey
e coli
klebsiella
colonies that don’t ferment in maconkey
almonella
shigella
pseudomonas aeruginosa
Incubation of maconkey
NEVER in co2
Hektoen enteric agar is used for
differentiation of salmonella and shigella
Organisms that ferment sucrose, salicin, or lactose in hektoen agar turn
oranfe
Salmonella and shigella appear ____ in hektoen agar
greenish-blue translucent
Reduction to H2S in salmonella on hektoen agar turns the colonies
black
Colony count of ___ is usually acceped criteria for urinary tract infection
100,000 colonies/ml
Organisms containing narrow spectrum beta lactamases
many different
organisms with ESBLs
gram negatives
organisms with ampc beta lactamases
enterobacter/pseudomonas
organisms with carbapenemases
gram-neg
organisms with altered penicillin binding proteins
staph
strep pneumonia/ Neisseria gon
organisms with VanA/B
enterococi
Organisms with macrolide resistance
staph/strep
organisms with fluoroquinilone resistance
gram pos and neg
organisms with aminoglycoside resistance
gram pos and neg
3 narrow spectrum beta lactamases
bla- staph (plasmid)
TEM-1- E. coli, h flu (plasmid)
SHV-1- k. pneumonia (chromosome)
Difference between extended spectrum beta lactamases and narrow
ESBLs attack cephaloporins (instead of just penicillins)
ESBLs are found on
Plasmids
ampC is found on
chromosomes
ampC is capable of hydrolyzing
penicillins, and all 1,2,3 cephs
ampC is induced by
Some but not all beta lactams (ampicillin, cefazolin)
2 carbapenemases
- KPC
- NDM-1
Pseudomonas that is carbapenem resistant… due to carbapenemases?
NOOOOOOO
- other mechanisms can cause resistance
Altered PBPs in strep pneumo and n gonorrhea
Mosaic PBPs
vanA and vanB are carried on
plasmids
Staph aureus reduced susceptibility to vanco
VISA
vancomycin intermediate susceptibility s aureus (VISA)
- markedly thickened peptidoglycan
- less cross linking of peptides
Quinolone resistance occurs due to mutations in ___ of DNA gyrase or ___ of topo IV
GyrA
ParC
erm is induced by
macrolides only, not clindamycin
Cefazolin (1st generation cephalosporin) generally has activity against all of the following organisms EXCEPT
A. Streptococcus pyogenes (Group A Strep)
B. Streptococcus pneumoniae
C. Methicillin-sensitive Staphylococcus aureus (MSSA)
D. Viridans streptococci
E. Enterococcus spp
E
enterococcus are resistant to all cephs
. Which of the following drugs would be expected to have activity against an E. coli organism containing a narrow-spectrum beta-lactamase (penicillinase) A. Ampicillin B. Oxacillin C. Amoxicillin-clavulanate D. Vancomycin
C
Not B cause not effective for gram negs