Intro to ID pt2 Flashcards
1
Q
what color do gram-pos bacteria appear as
A
purple
2
Q
what color do gram-neg bacteria appear as
A
red/pink
3
Q
which one has thick cell wall
A
gram positive
4
Q
what is the bacteria called when it does not stain using normal methods
A
atypical bacteria
5
Q
what is it called when the bacteria is resistant to acids/ethanol based decolorization procedures
A
acid-fast bacilli (AFB)
6
Q
2 most important morphologies for gram-positive bacteria
A
COCCI and Bacilli
7
Q
Cocci: categorized into clusters and chains
A. Anaerobic
B. Aerobic
A
B
8
Q
aerobic cocci:
strep A and strep B belong to this categorization:
A. clusters
B. pairs/chains
A
B
9
Q
aerobic cocci:
coagulase tests are done in which categorization:
A. Clusters
B. Pairs/chains
A
A
10
Q
Enterococcus faecium and Enterococcus faecalis fall under what categorization?
A. anaerobic bacilli
B. Aerobic bacilli
C. Aerobic cocci clusters
D. Aerobic cocci pairs/chains
A
D, these are also nonhemolytic
11
Q
T or F: Most medically important pathogens are cocci rather than bacilli
A
true
12
Q
T or F:
Staphylococcus form pairs or chains and Streptococci & Enterococci appear in clusters
A
false, other way around
13
Q
what biochemistry testing do you use for staphylococci from streptococci
A
catalase test
14
Q
what biochemistry test do you use for staphylococcus aureus from coagulase-negative staphylococcus (CoNS)
A
coagulase test
15
Q
You receive a call from the microbiology lab informing you that patient JR has Gram- positive cocci growing in the blood. They don’t have a full identification but tell you the organism is catalase positive, coagulase positive. Which of the following organisms could be growing in JR’s blood?
A. Staphylococcus aureus
B. Staphylococcus epidermidis
C. Streptococcus pyogenes
D. Enterococcus faecalis
A
A, pretty much choose that if you see coagulase positive i think
16
Q
what categorization does enterobacterales fall under?
A
gram-negative aerobic bacilli
17
Q
how do you remember the enterobacteriales lactose-fermenters?
A
CEEK out lactose
Citrobacter
Enterobacter
E.Coli
Klebsiella
(THESE ARE OXIDASE-NEGATIVE)
18
Q
do lactose-fermenters fall under anaerobic or aerobic bacilli
A
aerobic
19
Q
T or F:
Non-lactose fermenters tend to be more drug resistant than their friends the lactose fermenters
A
true
20
Q
try to think of things for slide 15
A
okay will do buddy
21
Q
what is one common bacteria that falls under atypical (at least on slide 16 it does)
A
chlamydia
22
Q
for gram-negative morphology, what is the predominant pathogen type?
A
bacilli
23
Q
what kind of test helps distinguish between enteric vs. non-enteric lactose fermenters
A
oxidase, thats why some are oxidase positive and some are oxidase negative duh
24
Q
what organisms are “slow growers” that require special supplemental media
A
fastidious organisms
25
You receive a call from the microbiology lab informing you that patient ZE has Gram negative rods growing in the blood. They don’t have a full identification but tell you the organism is a non-enteric non-lactose fermenter. Which of the following organisms could be growing in JR’s blood?
A. Pseudomonas aeruginosa
B. Citrobacter freundii
C. Morganella morganii
D. Aeromonas hydrophila
A, he said to know this for the exam
26
whats another way to say non-enteric lactose fermenter
oxidase-positive lactose-fermenter
27
what type of protein are transpeptidases, carboxypeptidases, and endopeptidases
penicillin-binding proteins (PBPs)
28
of the 3 PBPs, which one is most important and why?
transpeptidase, catalyzes the final cross linking in the peptidoglycan structure
29
where are penicillin-binding proteins located?
in bacteria
30
what significant thing binds to penicillin-binding proteins
Beta lactams!!!*
31
what are PBPs most essential for?
cell-wall synthesis
32
what are the hydrophilic channels that permit diffusion of essential nutrients and small hydrophilic compounds called
porins
33
what is the compartment between cell membrane and cell wall (or outer membrane if GN) called?
periplasmic space
34
which of the following is vital for bacterial protein secretion, folding, quality control and acts as a reservoir for virulence factors?
A. Cytoplasmic membrane
B. Peptidoglycan layer (cell wall)
C. Outer membrane (GN)
D. Periplasmic space
D
35
what are the two mechanisms by which intrinsic resistance occurs?
absence of target site
bacterial cell impermeability (cant get through)
36
what is the definition of acquired resistance
initially susceptible but develop resistance due to a mechanism
37
what are the two mechanisms by which acquired resistance occurs (general ass answers)
mutation in bacterial DNA
acquisition of new DNA
38
cephalosporins vs. enterococci
A. intrinsic
B. Acquired
A
39
Stable derepression of AmpC
A. intrinsic
B. Acquired
B
40
Acquisition of KPC gene in GNRs
A. intrinsic
B. Acquired
B
41
B-lactams vs. mycoplasma
A. intrinsic
B. Acquired
A
42
plasmid, transposons, and conjugation all relate to which type of resistance?
acquired
43
transferable between organisms
A. Plasmid
B. Conjugation
C. Transposons
A
44
move from plasmid to chromosome or vice versa
A. Plasmid
B. Conjugation
C. Transposons
C
45
most common and referred to as "mating bridge"
A. Plasmid
B. Conjugation
C. Transposons
B
46
referred to as "jumping genes"
A. Plasmid
B. Conjugation
C. Transposons
C
47
what is the MOA of beta-lactamase?
hydrolyze beta-lactam ring by splitting amide bond -> inactivating drugs
48
what are the two classification systems of beta-lactamase?
ambler class
Bush-Jacoby-Medeiros
49
classified according to AA structure (A-D)
A. ambler class
B. Bush-Jacoby-Medeiros
A
50
classified according to functional characteristics
A. ambler class
B. Bush-Jacoby-Medeiros
B
51
serine beta-lactamases contain a _____ residue at active site
serine no shit
52
metallo beta-lactamases contain _____ residue at active site
zinc, easy to remember bc its a metal
53
uses acylation and deacylation in mechanism
A. serine beta-lactamase
B. zinc beta-lactamase
A
54
skips intermediate step and just opens ring as part of its mechanism
A. serine beta-lactamase
B. zinc beta-lactamase
B, think metal can force through things and shit idk
55
Ambler classification:
what do narrow-spectrum B-lactamases hydrolyze?
penicillin
56
Ambler classification:
Narrow-spectrum B-lactamases are produced primarily by what bacteria?
enterobacterales
57
Ambler classification:
what do Extended-spectrum B-lactamases hydrolyze?
narrow & extended spectrum B-lactam (3rd gen cephalosporins)
58
Ambler classification:
bolded enzyme example for extended-spectrum B-lactamases (ESBL)
CTX-M-15 ****
59
Ambler classification:
bolded enzyme(s) example for serine carbapenemases ****
KPC-1, KPC-2, KPC-3
60
ambler classification:
what do serine carbapenemases hydrolyze?
carbapenems (WOAH)
61
Ambler classification:
what do metallo-B-lactamases hydrolyze?
carbapenems
62
T or F:
Serine carbapenems are more broad than metallo ones
false, other way around
63
Ambler classification:
bolded enzyme(s) example for metallo-B-lactamases
NDM-1 **
64
cephalosporinases didnt have any hydrolysis mechanisms listed, what was the one word characteristic used in that slot instead?
inducible
65
Ambler classification:
bolded enzyme(s) example for cephalosporinases
Amp-C*
66
Ambler classification:
bolded enzyme(s) example for OXA-type
OXA-48 (no way)
67
ambler classification:
what does OXA-type hydrolyze (3)
oxacillin, oxyimino B-lactams, and carbapenems
68
which resistant-related enzyme is most prevalent in Escherichia coli, Klebsiella pneumoniae/oxytoca, and Proteus mirabilis? What ambler class is it?
CTX-M, ESBLs
69
which of the following is not a beta-lactam agent?
A. Penicillin
B. Ciprofloxacin
C. Monobactams
D. Cephalosporins
B, thats a quinolone
70
what is the treatment of choice when dealing with ESBL-based resistance?
carbapenems
71
in ESBL-based resistance, piperacillin/tazobactam is an option for ______ source only
urinary
72
what enzyme is responsible for the most frequent cause of carbapenem-resistant enterobacterales (CRE)?
carbapenemase
73
T or F:
CRE leads to resistance of the whole beta-lactam class
true
74
look at the tx options on slide 34 again that looks wrong somehow
okay
75
T or F:
Metallo-B-lactamases confer resistance to all B-lactams
false, the exception is monobactams (aztreonam)
76
Cefiderocol; aztreonam + ceftazidime/avibactam are the only treatment option for what ambler class type?
metallo-B-lactamases
77
which ambler class and type is primarily found in acinetobacter baumannii and pseudomonas aeruginosa?
Class D, OXA-type
78
2 tx options for OXA-type resistance
cefiderocol
sulbactam/durlobactam
79
T or F:
carbapenem-resistant enterobacterales means that carbapenemases are present
false (slide 37)
80
Efflux pumps and porin mutations
A. CP(carbapenem producing)-CRE
B. Non-CP-CRE
B
81
AmpC and ESBLs
A. CP (carbapenem producing)-CRE
B. Non-CP-CRE
B
82
JM is a 45 YOM admitted with fever, chills, urinary frequency and urgency. Blood cultures are collected and 12 hour after admission rapid diagnostic testing identifies E.coli, CTX-M (+) in 4/4 bottles.
What type of antibiotic resistance is present?
A. Non-CP CRE
B. ESBL
C. NDM
D. KPC
B, CTX-M = ESBL
83
JM is a 45 YOM admitted with fever, chills, urinary frequency and urgency. Blood cultures are collected and 12 hour after admission rapid diagnostic testing identifies E.coli, CTX-M (+) in 4/4 bottles.
What is the recommended treatment option?
A. Meropenem
B. Meropenem/vaborbactam
C. Aztreonam + Ceftazidime/avibactam
D. Piperacillin/tazobactam
A, treatment of choice for ESBL is carbapenems, dont know what the combo one is though
84
mechanisms of AmpC beta-lactamases:
- inducible via ____________ ________ AmpC genes
- Non-inducible chromosomal resistance via __________
- ________-mediated resistance
- chromosomally encoded
- mutations
- plasmid
85
what does "inducible via chromosomally encoded AmpC genes mean in english?
some bacteria produce AmpC enzymes when exposed to certain antibiotics, making them resistant
86
T or F:
Non-inducible chromosomal resistance via mutations can happen without exposure to antibiotics
true actually
87
what does plasmid-mediated resistance mean in english?
resistance genes can be carried on plasmids which are small DNA fragments that can transfer between bacteria which spreads resistance
88
which of the following choices would inhibit AmpC?
A. avibactam
B. clavulanic acid
C. sulbactam
D. tazobactam
A, this is a "newer" B-lactamase inhibitor meaning that it is actually able to inhibit AmpC
89
what is the easy way to remember common bacteria producing AmpC beta-lactamases
HECK-YES:
Hafnia alvei
Enterobacter cloacae
Citrobacter freundii
Klebsiella aerogenes
Yersinia enterocolitica
90
if something is called an "AmpC inducer", what does this mean?
it means it is a bacteria that produces AmpC when exposed to certain antibiotics
91
if you were to add "ma'am" to the end of HECK YES, what bacteria would you be talking about?
Morganella morganii
Aeromonas hydrophila
92
what in the fuck is slide 42 trying to say
no idea
93
is Ceftriaxone a strong or weak AmpC inducer?
weak
94
what is the significance of ceftriaxone being a weak inducer?
it doesnt stimulate production of ampc as much as other options, making it less likely to cause resistance
95
go look at slide 44
yes sir
96
JH is a 65 YOM admitted with pyelonephritis (infection in the kidney) and started on IV ceftriaxone. However, he soon develops a fever and becomes hypotensive. Blood cultures are taken and result for E. cloacae.
What could explain his sudden decompensation?
A. cloacae harbors an ESBL gene and this was induced with ceftriaxone treatment
B. cloacae harbors a KPC gene and this was induced with ceftriaxone treatment
C. cloacae harbors an AmpC gene and this was induced with ceftriaxone treatment
D. cloacae harbors a NDM gene and this was induced with ceftriaxone treatment
C, because ceftriaxone is a weak inducer of AmpC
97
do carbapenems have a high or low susceptibility to AmpC hydrolysis?
low, this makes them a good treatment option
98
JH is a 65 YOM admitted with pyelonephritis (infection in the kidney) and started on IV ceftriaxone. However, he soon develops a fever and becomes hypotensive. Blood cultures are taken and result for E. cloacae. Ceftriaxone caused resistance through inducing ampC.
What antibiotic change do you recommend?
Switch to
A. Piperacillin/tazobactam
B. Switch to Cefepime
C. Switch to Ceftazidime
D. Switch to Aztreonam
B
99
what is the most common method of aminoglycoside resistance?
enzymatic inactivation
100
what are the 3 mechanisms involved in enzymatic inactivation for aminoglycosides?
acetylation
nucleotidylation
phosphorylation
101
what is the mechanism of vancomycin resistance in enterococci species?
altered target sites
102
vancomycin MOA
a glycopeptide antibiotic that inhibits bacterial cell wall synthesis by binding to D-Ala-D-Ala terminal of peptidoglycan precursors
103
T or F:
Vanco spec of activity is limited to gram-negative bacteria only
false, GP only
104
most common resistance mech for vanco
VanA or VanB mediated resistance by altering any formation of D-Ala whatever
105
two treatment options for VRE
daptomycin
linezolid
106
T or F:
Alterations in PBPs (penicillin binding proteins) leads to B-lactam resistance
true
107
where do we most commonly see alterations in PBPs?
methicillin-resistant Staphylococcus aureus (MRSA)****
108
MRSA related resistance is due to expression of what very important gene?
mecA
109
so if you see mecA what two things do you think about and vice versa
MRSA
Staph aureus
110
do porin channels help antibiotics into bacteria or pump them out?
helps perfuse into bacteria
111
Important resistance mechanism for P. aeruginosa against carbapenems
A. efflux pumps
B. Porin channels
A
112
Important resistance mechanism for S. pneumoniae against macrolide antiobiotics
A. efflux pumps
B. Porin channels
A
113
Important resistance mechanism for Enterobacterales and carbapenem-resistant P. aeruginosa
A. efflux pumps
B. Porin channels
B
114
What is the mechanism of Staphylococcus aureus resistance to beta-lactams?
A. mecA gene
B. VanA gene
C. ermB gene
D. KPC gene
A, always associate with mecA
115
Based on ADME
A. PK
B. PD
A
116
PK/PD terminology:
conc dependent
max conc at binding site
117
PK/PD terminology:
time dependent
optimize duration of exposure at binding site
118
PK/PD terminology:
Bactericidal
kills organism
119
PK/PD terminology:
Bacteriostatic
inhibit bacterial replication WITHOUT killing organism
120
PK/PD terminology:
AUC
overall drug exposure over a certain time
121
T or F:
Time that free drug conc remains above MIC correlates with clinical and microbiological outcomes (fT>MIC)
true, basically just saying that the longer the drug is above MIC and the has a high concentration correlates with how well the drug kills bacteria
122
Penicillin
A. fT>MIC 50%
B. fT>MIC 60-70%
C. fT>MIC 40%
A
123
Cephalosporin
A. fT>MIC 50%
B. fT>MIC 60-70%
C. fT>MIC 40%
B
124
Carbapenem
A. fT>MIC 50%
B. fT>MIC 60-70%
C. fT>MIC 40%
C
125
4 ways to maximize fT>MIC
- inc dose, same interval
- same dose shorter interval
- cont. infusion
- prolonged infusions
126
Goal AUC0-24/MIC for vanco
400-600
127
prolonged or elevated AUC0-24/MIC for vanco has a risk for what and at what range?
nephrotox
600-700
128
fluoroquinolones
A. time dependent
B. conc dependent
B****
129
aminoglycosides
A. time dependent
B. conc dependent
B*****
130
B-lactams (penicillin, cephalosporin, carbapenem, monobactam)
A. time dependent
B. conc dependent
A
131
Which of the following describes the PK/PD parameters of meropenem?
A. Time-dependent antibiotic; fT>MIC 40% of the dosing interval
B. Concentration dependent antibiotic; fAUC/MIC
C. Time-dependent antibiotic; fT>MIC 80% of the dosing interval
D. Concentration dependent antibiotic; Cmax/MIC
A (40% for carbapenems)
132
vancomycin
A. time dependent
B. conc dependent
A
