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Dr.T.V.Rao MD
DRUG RESISTANT GRAM-NEGATIVE
BACTERIA
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Bugs, No Drugs: No ESKAPE
Enterococcus faecium (E), Staphylococcus aureus (S), Klebsiella
pneumoniae (K),Acinetobacter baumannii(A), Pseudomonas aeruginosa
(P), and Enterobacterspp. (E)ate-stage clinical development
pipeline remains unacceptably lean
Some important molecules for problematic pathogens
such as MRSA
Few novel molecules for other ESKAPE pathogens
No new drugs for infection due to multidrug-resistant Gram-negative
bacilli (eg,A. baumanniiand P. aeruginosa)
None represent more than an incremental advance over currently
available therapies
NO ESKAPE ? FROM PATHOGENS
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EXTENDED-SPECTRUM -LACTAMASES (ESBLS):
THE FORGOTTEN (AND UNDERRATED) MDR GNB
Most commonly identified in enterobacteriaceae
Plasmid-mediated
Impart decreased susceptibility to -lactam
antimicrobials
Often co-resistance to aminoglycosides,fluoroquinolones
Carbapenems are drugs of choice for invasive
infections due to ESBL-producers 08-12-2012DR.T.V.RAO MD 3
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ESBLs are enzymes
capable of
hydrolysing
penicillins, broad-
spectrum
cephalosporins and
Monobactams, andare generally derived
from TEM and SHV-
type enzymes
WHAT ARE ESBL
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ALEXANDER FLEMINGNOBEL LECTURE, DECEMBER 11, 1945
It arose simply from a fortunate occurrence which happened when I
was working on a purely academic bacteriological problem which had
nothing to do with antagonism, or moulds, or antiseptics, or
antibiotics.
www.nobelprize.org
Google images
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Abx Penicillin
Cephalosporin
Monobactam
Carbapenem
Bactericidal
WHAT IS A BETA-LACTAM?
Google Images
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Enterobacteriaceae
Resistance to
oxyimino-
cephalosporins andmonobactams but
not cephamycins and
carbamenems
Susceptible to
beta-lactamase
inhibitors
ESBLS
Oteo, et al., 201008-12-2012DR.T.V.RAO MD 7
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SHV
TEM
CTX-M
OXA
AmpC
GENES
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CLASSIFICATION Ambler Classification
Molecular class A D
A
Bush-Jacoby-Medeiros Classification
Functional group 1 4
2
2b
2be
Paterson and Bonomo, 200508-12-2012DR.T.V.RAO MD 9
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Mid 1980s
Variants of TEM and
SHV
Breakdown 3rd
generation
cephalosporins
Mainly in hospitalKlebsiella
Spread world wide
ESBL EVOLUTION
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ESBLs are often
located on
plasmids that aretransferable from
strain to strain and
between bacterialspecies.
WHERE ESBL ARE LOCATED
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Common ESBL worldwide, often produced by
Escherichia coli
Often causes UTI
Now reported in US Healthcare associated
Some community
Community-based ESBL infection raiseconcern for continued increases in
carbapenem use
CTX-M: ESBL EPIDEMIC
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WHY WE NEED ESBL DETECTION
ESBL-producing Enterobacteriaceae have been
responsible for numerous outbreaks of infection
throughout the world and pose challenging infection
control issues. Clinical outcomes data indicate thatESBLs are clinically significant and, when detected,
indicate the need for the use of appropriate
antibacterial agents.
Unfortunately, the laboratory detection of ESBLs can be
complex and, at times, misleading.
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ESBL PRODUCING BACTERIA ARE MORE
COMPLEX ?
Antibacterial choice is often complicated by
multi-resistance. Many ESBLproducing
organisms also expressAmpC -lactamases and may be co-transferredwith
plasmids mediating aminoglycoside
resistance. In addition, there is anincreasing association between ESBL
production and fluoroquinolone resistance
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DYNAMICS OF ANTIBIOTIC
RESISTANCE
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1st generation
Extended-
spectrum With or w/o
beta-lactamase
inhibitor Broad spectrum
PENICILLINS
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CEPHALOSPORINS
Willey, et al., 2008
1st
2nd
3rd
4th
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Although in in vitro tests
ESBLs are inhibited by
-lactamase inhibitors such
as clavulanic acid, the
activity of -lactam/-lactamase inhibitor
combination agents is
influenced by the bacterial
inoculum, doseadministration regimen and
specific type of ESBL
present
ESBL DYNAMICS
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Beta-lactam
Beta-lactamase
Beta-lactamase
inhibitor
ESBL
THE FIGHT
Google Images
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THE FIGHT
BETA-LACTAM
cell
PG
NO
LYSIS08-12-2012DR.T.V.RAO MD 20
THE FIGHT
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THE FIGHT
BETA-LACTAMASE
cell
PG
NO
beta-lactamase
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THE FIGHT
BETA-LACTAMASE
cell
PG
NHO
OH
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THE FIGHT
BETA-LACTAMASE INHIBITOR
cell
PG
NO
beta-lactamase
Inhibitor
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THE FIGHT
BETA-LACTAMASE INHIBITOR
cell
PG
NO
beta-lactamase
Inhibitor
LYSIS08-12-2012DR.T.V.RAO MD 24
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WHAT ARE EXTENDED-SPECTRUM
-LACTAMASES?
ESBLs are enzymes that mediate
resistance to extended-spectrum (third
generation) cephalosporins (e.g.,ceftazidime, cefotaxime, and ceftriaxone)
and monobactams (e.g., aztreonam) but do
not affect cephamycins (e.g., cefoxitin andcefotetan) or Carbapenems (e.g.,
meropenem or imipenem
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WHY SHOULD CLINICAL LABORATORY PERSONNEL BE
CONCERNED ABOUT DETECTING THESE ENZYMES?
The presence of an ESBL-producing organism in a clinicalinfection can result in treatment failure if one of the above
classes of drugs is used. ESBLs can be difficult to detect
because they have different levels of activity against
various cephalosporins. Thus, the choice of whichantimicrobial agents to test is critical. For example, one
enzyme may actively hydrolyze ceftazidime, resulting in
ceftazidime minimum inhibitory concentrations (MICs) of
256 g/ml, but have poor activity on cefotaxime, producing
MICs of only 4 g/ml. If an ESBL is detected, all penicillins,
cephalosporins, and aztreonam should be reported as
resistant, even if in vitro test results indicate susceptibility08-12-2012DR.T.V.RAO MD 26
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HOW CAN CLINICAL LABORATORY
PERSONNEL CONFIRM ESBL PRODUCTION?
NCCLS recommends performing phenotypic confirmation of
potential ESBL-producing isolates of K. pneumoniae, K.
oxytoca, or E. coli by testing both cefotaxime and ceftazidime,
alone and in combination with clavulanic acid . Testing can be
performed by the broth micro dilution method or by diskdiffusion. For MIC testing, a decrease of > 3 doubling dilutions
in an MIC for either cefotaxime or ceftazidime tested in
combination with 4 g/ml clavulanic acid, versus its MIC when
tested alone, confirms an ESBL-producing organism. For diskdiffusion testing, a > 5 mm increase in a zone diameter for either
antimicrobial agent tested in combination with clavulanic acid
versus its zone when tested alone confirms an ESBL-producing
organism.08-12-2012DR.T.V.RAO MD 27
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CLINICAL STRATEGY TO DETECT
ESBL
CTX CTX/CLA
CAZ CAZ/CLA
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NCCLS suggests making
disks by adding 10 l of a
1000 g/ml stock solution
of clavulanic acid to
cefotaxime and ceftazidimedisks each day of testing .
In the future, commercial
manufacturers of
antimicrobial disks mayproduce disks containing
cefotaxime and ceftazidime
with clavulanic acid.
HOW SHOULD LABORATORY PERSONNEL TEST FOR
CEFOTAXIME AND CEFTAZIDIME IN COMBINATION WITH
CLAVULANIC ACID?
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Common ESBL worldwide, often produced by
Escherichia coli
Often causes UTI
Now reported in US Healthcare associated
Some community
Community-based ESBL infection raise concern
for continued increases in carbapenem use
CTX-M: ESBL EPIDEMIC
Urban, Diag Micro Infect Dis, 2010; Sjlund-Karlsson, EID, 201108-12-2012DR.T.V.RAO MD 30
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CARBAPENEM RESISTANCE
Emerging problem in Pseudomonasaeruginosa,Acinetobacter baumannii,Enterobacteriaceae (CRE)
Risk factors include ICU stay, prolongedexposures to healthcare, indwelling devices,antibiotic exposures
Long-term acute care centers (LTACs)
Severely limits treatment options
Increased use of older, toxic agents such ascolistin
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KLEBSIELLA PNEUMONIAECARBAPENEMASES (KPCS)
Plasmid-mediated carbapenemases
KPC-producing strains ofKlebsiella pneumonia and other
enterobacteriaceae
KPC-2, KPC-3
Endemicity in many locales in the US
Hyperendemicity in NYC
24% of K. pneumoniae infections were due to KPCs in 2
hospitals
Country-wide outbreak ongoing in Israel, Greece, Columbia and
others
*08-12-2012DR.T.V.RAO MD 32
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KPCS (CONT)
Might appear susceptible to imipenem ormeropenem, but with borderline MICs per 2009 CLSI
breakpoints
Usually Ertapenem resistant Modified Hodge test
Usually only susceptible to colistin, Tigecycline and
select aminoglycosides Easily spread in hospitals (often requires Cohorting of
staff and patients to control)
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Other isolates ofEnterobacteriaceae, suchas Salmonella species andProteus mirabilis, andisolates of Pseudomonasaeruginosa produceESBLs. However, at thistime, methods for screeningand phenotypicconfirmatory testing of
these isolates have notbeen determined byNCCLS.
DO ISOLATES OTHER THAN K. PNEUMONIAE,
K. OXYTOCA, OR E. COLI PRODUCE ESBLS?
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HOW SHOULD CEPHALOSPORIN AND
PENICILLIN RESULTS BE REPORTED?
08-12-2012DR.T.V.RAO MD 35
If an isolate is confirmed as an ESBL-producer by the
NCCLS-recommended phenotypic confirmatory test
procedure, all penicillins, cephalosporins, and
aztreonam should be reported as resistant. This listdoes not include the Cephamycins (cefotetan and
cefoxitin), which should be reported according to their
routine test results. If an isolate is not confirmed as an
ESBL-producer, current recommendations suggestreporting results as for routine testing. Do not change
interpretations of penicillins, cephalosporins, and
aztreonam for isolates not confirmed as ESBL
BACTERIA NOT TO TEST FOR
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Acinetobacter
Often S to clavulanate
alone
S. maltophila +ve resultby inhibition of L-2
chromosomal b-
lactamase, ubiquitous
in the species
BACTERIA NOT TO TEST FOR
ESBLS
08-12-2012DR.T.V.RAO MD 36
NEW DELHI METALLO BETA LACTAMASE 1
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NEW DELHI METALLO-BETA-LACTAMASE-1
(NDM-1)
Carbapenemases mediating broad spectrumresistance
Usually found in Klebsiella pneumonia, E. coli
Initially identified in India, Pakistan, Bangladesh
Recovered in Australia, France, Japan, Kenya,
North America, Singapore, Taiwan, and the United
Kingdom, Australia, Canada
Recovered in the US (Massachussetts, Illinois and
California)08-12-2012DR.T.V.RAO MD 37
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MDR GNB IN LONG TERM CARE
Quinolone resistance increasingly common in
hospitals, long-term care and in some community
settings
B-lactam resistance established in hospitals, many
long-term care settings
Risk factors in long-term care for resistant Gram-
negative bacilli
Indwelling devices Poor functional status
Pressure ulcers/wounds
Antimicrobial/quinolone exposure
Prior hospitalization 08-12-2012DR.T.V.RAO MD 38
STRATEGIES TO CONTROL THE
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Contact
precautions/hand
hygiene
Environment andsource control
Antibiotic stewardship
Enhanced infectioncontrol measures
Bundles
STRATEGIES TO CONTROL THE
SPREAD OF MDR GNB
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ROLE OF THE ENVIRONMENT
Environmental sources of contamination/infection
Increasingly recognized as sources of infection
Particularly important with pathogens such asClostridium difficile, Norovirus,Acinetobacterspp.
Bleach preparations are more effective for somepathogens (still need cleaning)
Latest technology being tested: UV light,
hydrogen peroxide vapor08-12-2012DR.T.V.RAO MD 40
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ENVIRONMENTAL CLEANING Adequacy of cleaning of patients rooms
suboptimal
Improve monitoring and feedback of efficacy of
cleaning
Direct observation and culturing not efficient, time-
consuming and expensive
Other options: ATP bioluminescence andfluorescent dyes
Monitor process, efficacy of cleaning08-12-2012DR.T.V.RAO MD 41
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SUPPLEMENTS TO ROUTINE ENVIRONMENTAL
CLEANING
Disinfection units that decontaminate
environmental surfaces
Must remove debris and dirt in order forthese units to be effective
Two most common methods
UV light
Hydrogen peroxide (HP)
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Broad-spectrumantimicrobial disinfectant
Preferred agent for skinpreparation prior to
insertion of vascularcatheter and prior tosurgery
Studied for source control,
decrease in degree ofcontamination of patientsby problem hospitalpathogens
CHLORHEXIDINE GLUCONATE (CHG)
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ENHANCED INFECTION CONTROL PROCESSES
Active Surveillance
Use of screening cultures to identify patients colonized with
pathogens (usually MDR) of interest
Goal is to prevent spread in the hospital by identifying patients who
are colonized and intervening to prevent spread Most experience is with Gram positive pathogens
Limited use for some pathogens (due to low sensitivity)
Cohorting of patients
Dedicated staff
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ANTIMICROBIAL STEWARDSHIP - GOALS
Optimize appropriate use of antimicrobials The right agent, dose, timing, duration, route
Optimize clinical outcomes
Reduce emergence of resistance
Limit drug-related adverse events
Minimize risk of unintentional consequences
Help reduce antimicrobial resistance
The combination of effective antimicrobial stewardship andinfection control has been shown to limit the emergence andtransmission of antimicrobial-resistant bacteria
Dellit TH et al. Clin Infect Dis. 2007;44(2):159177; . Drew RH. J Manag Care Pharm.2009;15(2 Suppl):S18S23; Drew RH et al. Pharmacotherapy. 2009;29(5):593607.
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A bundle is a structuredway of improving theprocesses of care andpatient outcomes: a
small, straightforwardset of evidence-basedpractices that, whenperformed collectivelyand reliably, have been
proven to improvepatient outcomes.
Resar R, Joint Commission Journalon ualit and Patient Safet .
BUNDLES
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CONCLUSIONS MDR GNB are growing in prevalence in multiple
geographic locales Occur in a variety of healthcare associated
settings
Even in the community Antimicrobial stewardship is here to stay
Problem is compounded by dry pharmaceutical
pipeline Novel methods to control spread of MDROs are
attractive but not clearly effective/cost-effective
08-12-2012DR.T.V.RAO MD 47
NEW DELHI METALLO BETA LACTAMASE 1
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NEW DELHI METALLO-BETA-LACTAMASE-1
(NDM-1)
Carbapenemases mediating broad spectrumresistance
Usually found in Klebsiella pneumonia, E. coli
Initially identified in India, Pakistan, Bangladesh
Recovered in Australia, France, Japan, Kenya,
North America, Singapore, Taiwan, and the United
Kingdom, Australia, Canada
Recovered in the US (Massachussetts, Illinois and
California)08-12-2012DR.T.V.RAO MD 48
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STILL THE BEST WAY TO PREVENT SPREAD OF
INFECTIONS AND DRUG RESISTANCE IS
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VISIT ME FOR MORE ARTICLES OF INTEREST
ON INFECTIOUS DISEASES
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Programme Created by Dr.T.V.Rao MD
for Microbiologists in the Developing
World
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