762 Module 2 2 Antimicrobial Resistance

Front 1

3 MOR against beta-lactams

Back 1

-beta lactamase production
-PBP alterations
-porin changes (carbapenems)

Front 2

define induction wrt beta lactamases

Back 2

extent to which an antibiotic causes beta-lactamase expression

strong v. weak

Front 3

define stability wrt beta lactamases

Back 3

susceptibility of an antibiotic to beta-lactamase activity

stable v. labile

Front 4

what is the ideal combination of stability and induction

Back 4

weak/stable

Front 5

1 weak/stable Abx

Back 5

cefepime (big gun)
for SPACE bugs

Front 6

4 weak/labile Abx

Back 6

-2nd gen cephalosporins
-3rd gen cephalosporins
-acylureidopenicililins
-aztreoname

Front 7

2 strong/stable Abx

Back 7

imipenem
meropenem

Front 8

2 strong/labile Abx

Back 8

1st gen cephalosporin
ampicillin

Front 9

2 MORs for macrolides and lincosides (clindamycin)

Back 9

"mef" gene produces macrolide efflux pump

"erm" alters rRNA binding site, MLSb phenotype for both macrolides and lincosides

Front 10

FQs MOR

Back 10

active efflux

DNA binding site alteration (gyrase, topoisomerase)

Front 11

tetracyclines MORs

Back 11

active efflux

rRNA binding site alteration

Front 12

vancomycin MOR

Back 12

alteration of peptidoglycan precursors

Front 13

2 ways bacteria can become resistant

Back 13

-mutations are transferred between bacteria
-due to selective pressure, rare resistant strains dominate upon replication

Front 14

2 ways to monitor resistance

Back 14

phenotypic resistance
genotypic resistance

Front 15

define phenotypic resistance

Back 15

-MIC
-elevation in MIC = resistance
-degree of elevation sometimes indicates response resistance mechanism

Front 16

define genotypic resistance

Back 16

-genetic sequencing to ID mutations
-not often performed in clinical practice
-$$$

Front 17

3 breakpoints

Back 17

susceptible
intermediate
resistant

Front 18

define susceptible breakpoint

Back 18

MIC of isolate at or below breakpoint

high likelihood of infection responding to normal dose of antimicrobial

Front 19

define intermediate breakpoint

Back 19

MIC of isolate above susceptible breakpoint but not above resistant breakpoint

less likelihood of infection responding to normal dose, but may respond to increased dose

AKA dose-dependent

Front 20

define resistant breakpoint

Back 20

MIC of isolate above intermediate breakpoint

higher likelihood of clinical failure if tested agent is used

Front 21

5 limitations of breakpoints

Back 21

-based on limited clinical evidence
-assume proper dosing of Abx
-breakpoints don't exist for some bacteria don't exist
-do different MIC values within a susceptibility category mean the same thing?
-what does "I" mean?

Front 22

3 types of susceptibility

Back 22

national
local
patient-specific

Front 23

2 ways to tell if resistance is being underestimated

Back 23

-D-test
-hidden (genetic) mechanisms not detected by MIC

Front 24

4 ways to prevent resistance

Back 24

-prevent infection
-effective diagnosis and treatment
-optimize Abx use
-prevent transmission

Front 25

8 ways to control infections

Back 25

-vaccination
-limiting use of catheters and other invasive devices
-infection control
-hygiene
-proper storage of infectious fluids
-accurate diagnosis of infection
-surveillance of resistance
-proper and effective antimicrobial use

Front 26

6 risk factors for S. pneumoniae

Back 26

-prone to otitis media
-old/young age
-HIV infection, nosocomial pneumonia
-prior hospitalization
-recent and/or repeated Abx use
-recent beta-lactam, SMX/TMP use

Front 27

2 components of proper antibiotic use

Back 27

"appropriate" use
- (susceptible)

"adequate" use
-agent with favorable activity
-favorable regimen and duration

Front 28

3 antimicrobial use strategies

Back 28

blast them - combo therapy

fool them - cycling

stop irritating them - antimicrobial restriction

Front 29

describe combination therapy

Back 29

-additivity or synergy to improve kill
-minimize resistance by using agents with unique resistance mechanisms
-no evidence to suggest this actually works

Front 30

describe antibiotic cycling

Back 30

"crop rotation"
-resistance appears to lessen, but returns
-many methodologic details remain unresolved
-works best in a closed environment
-multidrug resistance makes success impossible?

Front 31

describe antibiotic restriction

Back 31

-use of each antibiotic can lead to particular resistance problems
-FQ use = carbapenem resistance
-cephalosporine use = VRE
-restrict inappropriate/unnecessary use
-effects poorly understood

Front 32

the biggest driver of unnecessary antibiotic use is

Back 32

upper respiratory tract infections

Front 33

otitis media spontaneously resolves, so should only be used when...

Back 33

age up to 2 years with certain diagnosis

(uncertain diagnosis if <6 mo)

Front 34

4 ways to improve or regulate Abx use

Back 34

-prescriber education
-standard order forms
-formulary restrictions, PA programs
-pharmacy substitution/switches

Front 35

what does ESKAPE stand for

Back 35

E - VRE
S - MRSA
S - Streptococcus pneumoniae
K - ESBL-producing E. coli, Kleb
K - carbapenemase-producing Kleb
A - Acinetobacter baumannii
P - Pseudomonase aeruginosa
E - Enterobacter species

Front 36

describe VRE

Back 36

Enterococcus faecium > E. faecalis
-3rd most frequent cause of nosocomial bloodstream infections
-current vanco resistance rate is 60%
-little clinical data exists to prove efficacy of newer agents (linezolid, daptomycin, tigecycline)

Front 37

describe S. aureus and mef-mediated resistance

Back 37

EFFLUX of macrolides only
-results in low-level macrolide resistance
-clindamycin or a macrolide can be used

Front 38

describe S. aureus erm-mediated resistance

Back 38

RIBOSOMAL MODIFICATION
-affects all macrolides AND clindamycin
-results in high-level resistance (dramatic increase in MIC)
-cannot use a macrolide or clindamycin

Front 39

describe S. pneumoniae and FQs

Back 39

moxifloxacin is a superior agent in class

Front 40

describe S. pneumoniae in otitis media

Back 40

PRSP (penicillin resistant SP)
DRSP (drug resistant SP)

use high-dose amoxicillin to maximize PD to overcome resistance

Front 41

describe ESBL-producing E. coli, Klebsiella species

Back 41

ESBL = extended spectrum beta lactamase
-BLIs effectiveness is questionable
-MDR usually present
-difficult to detect by susceptibility testing
-if a cephalosporin is used, treatment failure will usually result

USE CARBAPENEMS

Front 42

describe P. aeruginosa

Back 42

role of piperacillin: a ureidoPCN w/ activity against P. aeruginosa

role of tazobactam: BLI

addn of tazobactam to piperacillin doesn't result in enhanced activity because tazobactam is not active against the particular beta lactamase produced

Front 43

describe Enterobacter species

Back 43

-may produce inducible beta-lactamases
-organism doesn't express beta-lactamase until it's exposed to a beta-lactam
-this type of beta-lactamase is not inhibited by beta-lactamase inhibitors

USE CARBAPENEMS OR CEFEPIME