11/04/2023DR.T.V.RAO MD 1

Dr.T.V.Rao MD

DRUG RESISTANT GRAM-NEGATIVE

BACTERIA

11/04/2023DR.T.V.RAO MD 2

Bugs, No Drugs: No ESKAPE– Enterococcus faecium (E), Staphylococcus aureus (S), Klebsiella

pneumoniae (K), Acinetobacter baumannii (A), Pseudomonas aeruginosa (P), and Enterobacter spp. (E)ate-stage clinical development pipeline remains unacceptably lean

– Some important molecules for problematic pathogenssuch as MRSA

– Few novel molecules for other ESKAPE pathogens– No new drugs for infection due to multidrug-resistant Gram-negative bacilli

(eg, A. baumannii and P. aeruginosa)– None represent more than an incremental advance over currently

available therapies

NO ESKAPE ? FROM PATHOGENS

11/04/2023DR.T.V.RAO MD 3

EXTENDED-SPECTRUM Β-LACTAMASES (ESBLS):THE FORGOTTEN (AND UNDERRATED) MDR GNB

• Most commonly identified in enterobacteriaceae • Plasmid-mediated • Impart decreased susceptibility to β-lactam

antimicrobials• Often co-resistance to aminoglycosides,

fluoroquinolones

• Carbapenems are drugs of choice for invasive infections due to ESBL-producers

11/04/2023DR.T.V.RAO MD 4

• ESBLs are enzymes capable of hydrolysing penicillins, broad-spectrum cephalosporins and Monobactams, and are generally derived from TEM and SHV-type enzymes

WHAT ARE ESBL

11/04/2023DR.T.V.RAO MD 5

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

11/04/2023DR.T.V.RAO MD 6

• Abx• Penicillin

• Cephalosporin

• Monobactam

• Carbapenem

• Bactericidal

WHAT IS A BETA-LACTAM?

Google Images

11/04/2023DR.T.V.RAO MD 7

• Enterobacteriaceae

• Resistance to oxyimino-cephalosporins and monobactams but not cephamycins and carbamenems

• Susceptible to beta-lactamase inhibitors

ESBLS

Oteo, et al., 2010

11/04/2023DR.T.V.RAO MD 8

• SHV• TEM• CTX-M• OXA

• AmpC

GENES

11/04/2023DR.T.V.RAO MD 9

CLASSIFICATION• Ambler Classification

• Molecular class A – D

• A

• Bush-Jacoby-Medeiros Classification

• Functional group 1 – 4

• 2

• 2b

• 2bePaterson and Bonomo, 2005

11/04/2023DR.T.V.RAO MD 10

• Mid 1980s

• Variants of TEM and SHV

• Breakdown 3rd generation cephalosporins

• Mainly in hospital Klebsiella

• Spread world wide

ESBL EVOLUTION

11/04/2023DR.T.V.RAO MD 11

• ESBLs are often located on plasmids that are transferable from strain to strain and between bacterial species.

WHERE ESBL ARE LOCATED

11/04/2023DR.T.V.RAO MD 12

•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

11/04/2023DR.T.V.RAO MD 13

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 that ESBLs 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.

11/04/2023DR.T.V.RAO MD 14

ESBL PRODUCING BACTERIA ARE MORE COMPLEX ?

• Antibacterial choice is often complicated by multi-resistance. Many ESBLproducing organisms also expressAmpC â-lactamases and may be co-transferredwith plasmids mediating aminoglycoside resistance. In addition, there is an increasing association between ESBL production and fluoroquinolone resistance

11/04/2023DR.T.V.RAO MD 15

DYNAMICS OF ANTIBIOTIC RESISTANCE

11/04/2023DR.T.V.RAO MD 16

• 1st generation

• Extended-spectrum

• With or w/o beta-lactamase inhibitor

• Broad spectrum

PENICILLINS

11/04/2023DR.T.V.RAO MD 17

CEPHALOSPORINS

Willey, et al., 2008

1st

2nd

3rd

4th

11/04/2023DR.T.V.RAO MD 18

• Although in in vitro tests ESBLs are inhibited by â-lactamase inhibitors such as clavulanic acid, the activity of â-lactam/â-lactamase inhibitor combination agents is influenced by the bacterial inoculum, dose administration regimen and specific type of ESBL present

ESBL DYNAMICS

11/04/2023DR.T.V.RAO MD 19

• Beta-lactam

• Beta-lactamase

• Beta-lactamase inhibitor

• ESBL

THE FIGHT

Google Images

11/04/2023DR.T.V.RAO MD 20

THE FIGHTBETA-LACTAM

cell

PG

NO

LYSIS

11/04/2023DR.T.V.RAO MD 21

THE FIGHTBETA-LACTAMASE

cell

PG

NO

beta-lactamase

11/04/2023DR.T.V.RAO MD 22

THE FIGHTBETA-LACTAMASE

cell

PG

NHO

OH

11/04/2023DR.T.V.RAO MD 23

THE FIGHTBETA-LACTAMASE INHIBITOR

cell

PG

NO

beta-lactamase

Inhibitor

11/04/2023DR.T.V.RAO MD 24

THE FIGHTBETA-LACTAMASE INHIBITOR

cell

PG

NO

beta-lactamase

Inhibitor

LYSIS

11/04/2023DR.T.V.RAO MD 25

WHAT ARE EXTENDED-SPECTRUM Β-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 and cefotetan) or Carbapenems (e.g., meropenem or imipenem

11/04/2023DR.T.V.RAO MD 26

WHY SHOULD CLINICAL LABORATORY PERSONNEL BE CONCERNED ABOUT DETECTING THESE ENZYMES?

• The presence of an ESBL-producing organism in a clinical infection 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 which antimicrobial agents to test is critical. For example, one enzyme may actively hydrolyze ceftazidime, resulting in ceftazidime minimum inhibitory concentrations (MICs) of 256 µg/ml, but have poor activity on cefotaxime, producing MICs of only 4 µg/ml. If an ESBL is detected, all penicillins, cephalosporins, and aztreonam should be reported as resistant, even if in vitro test results indicate susceptibility

11/04/2023DR.T.V.RAO MD 27

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 disk diffusion. For MIC testing, a decrease of > 3 doubling dilutions in an MIC for either cefotaxime or ceftazidime tested in combination with 4 µg/ml clavulanic acid, versus its MIC when tested alone, confirms an ESBL-producing organism. For disk diffusion 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.

CLINICAL STRATEGY TO DETECT ESBL

CTX

CTX/CLA

CAZ

CAZ/CLA

11/04/2023DR.T.V.RAO MD 29

• NCCLS suggests making disks by adding 10 µl of a 1000 µg/ml stock solution of clavulanic acid to cefotaxime and ceftazidime disks each day of testing . In the future, commercial manufacturers of antimicrobial disks may produce disks containing cefotaxime and ceftazidime with clavulanic acid.

HOW SHOULD LABORATORY PERSONNEL TEST FOR CEFOTAXIME AND CEFTAZIDIME IN COMBINATION WITH

CLAVULANIC ACID?

11/04/2023DR.T.V.RAO MD 30

•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; Sjölund-Karlsson, EID, 2011

11/04/2023DR.T.V.RAO MD 31

CARBAPENEM RESISTANCE• Emerging problem in Pseudomonas

aeruginosa, Acinetobacter baumannii, Enterobacteriaceae (CRE)

• Risk factors include ICU stay, prolonged exposures to healthcare, indwelling devices, antibiotic exposures• Long-term acute care centers (LTACs)

• Severely limits treatment options• Increased use of older, toxic agents such as

colistin

11/04/2023DR.T.V.RAO MD 32

KLEBSIELLA PNEUMONIAE CARBAPENEMASES (KPCS)

• Plasmid-mediated carbapenemases • KPC-producing strains of Klebsiella 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

*

11/04/2023DR.T.V.RAO MD 33

KPCS (CONT)• Might appear susceptible to imipenem or

meropenem, 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)

11/04/2023DR.T.V.RAO MD 34

• Other isolates of Enterobacteriaceae, such as Salmonella species and Proteus mirabilis, and isolates of Pseudomonas aeruginosa produce ESBLs. However, at this time, methods for screening and phenotypic confirmatory testing of these isolates have not been determined by NCCLS.

DO ISOLATES OTHER THAN K. PNEUMONIAE, K. OXYTOCA, OR E. COLI PRODUCE ESBL’S?

11/04/2023DR.T.V.RAO MD 35

HOW SHOULD CEPHALOSPORIN AND PENICILLIN RESULTS BE REPORTED?

• 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 list does 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 suggest reporting results as for routine testing. Do not change interpretations of penicillins, cephalosporins, and aztreonam for isolates not confirmed as ESBL

11/04/2023DR.T.V.RAO MD 36

• Acinetobacter

• Often S to clavulanate alone

• S. maltophila +ve result by inhibition of L-2 chromosomal b-lactamase, ubiquitous in the species

BACTERIA NOT TO TEST FOR ESBLS

11/04/2023DR.T.V.RAO MD 37

NEW DELHI METALLO-BETA-LACTAMASE-1

(NDM-1)• Carbapenemases mediating broad spectrum

resistance• 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)

11/04/2023DR.T.V.RAO MD 38

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

11/04/2023DR.T.V.RAO MD 39

• Contact precautions/hand hygiene

• Environment and source control

• Antibiotic stewardship

• Enhanced infection control measures

• Bundles

STRATEGIES TO CONTROL THE SPREAD OF MDR GNB

11/04/2023DR.T.V.RAO MD 40

ROLE OF THE ENVIRONMENT

• Environmental sources of contamination/infection • Increasingly recognized as sources of infection

• Particularly important with pathogens such as Clostridium difficile, Norovirus, Acinetobacter spp.

• Bleach preparations are more effective for some pathogens (still need cleaning)

• Latest technology being tested: UV light, hydrogen peroxide vapor

11/04/2023DR.T.V.RAO MD 41

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 and fluorescent dyes• Monitor process, efficacy of cleaning

11/04/2023DR.T.V.RAO MD 42

SUPPLEMENTS TO ROUTINE ENVIRONMENTAL CLEANING

• Disinfection units that decontaminate environmental surfaces

• Must remove debris and dirt in order for these units to be effective

• Two most common methods• UV light

• Hydrogen peroxide (HP)

11/04/2023DR.T.V.RAO MD 43

• Broad-spectrum antimicrobial disinfectant

• Preferred agent for skin preparation prior to insertion of vascular catheter and prior to surgery

• Studied for “source control”, decrease in degree of contamination of patients by problem hospital pathogens

CHLORHEXIDINE GLUCONATE (CHG)

11/04/2023DR.T.V.RAO MD 44

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

11/04/2023DR.T.V.RAO MD 45

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 and

infection control has been shown to limit the emergence and transmission of antimicrobial-resistant bacteria

Dellit TH et al. Clin Infect Dis. 2007;44(2):159–177; . Drew RH. J Manag Care Pharm. 2009;15(2 Suppl):S18–S23; Drew RH et al. Pharmacotherapy. 2009;29(5):593–607.

11/04/2023DR.T.V.RAO MD 46

• A bundle is a structured way of improving the processes of care and patient outcomes: a small, straightforward set of evidence-based practices that, when performed collectively and reliably, have been proven to improve patient outcomes.

Resar R, Joint Commission Journal on Quality and Patient Safety. 2005; 243-248

BUNDLES

11/04/2023DR.T.V.RAO MD 47

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

11/04/2023DR.T.V.RAO MD 48

NEW DELHI METALLO-BETA-LACTAMASE-1 (NDM-1)

• Carbapenemases mediating broad spectrum resistance• 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)

11/04/2023DR.T.V.RAO MD 49

STILL THE BEST WAY TO PREVENT SPREAD OF INFECTIONS AND DRUG RESISTANCE IS ……

11/04/2023DR.T.V.RAO MD 50

VISIT ME FOR MORE ARTICLES OF INTEREST ON INFECTIOUS DISEASES ……

11/04/2023DR.T.V.RAO MD 51

• Programme Created by Dr.T.V.Rao MD for Microbiologists in the Developing

World

• Email

• doctortvrao@gmail.com