The emerging threat posed by carbapenemase producing

enterobacteria &

how to address it

Dr. Ashok Rattan

Fortis Clinical Research Ltd.

Thienamycin

Streptomyces cattleya

Imipenem cilastatin

Meropenem Ertapenem Doripenem

+In 1 : 1 ratio

Spectrum of activity

• Broad spectrum activity– GPC & GNB– Aerobic & Anaerobic bacteria– Active against MDR isolates– Active against ESBL +ve GNB– Active against DRSP– Active against Ps aeruginosa & Acinetobacter spp.

• Not active against– MRSA– Entrococcus spp. – Stenotrophomonas maltophilia

Pramod M. Shah & Robin D. Isaacs Classification– Group 1: Broad spectrum for Community acquired infections

• Ertapenem

– Group 2: Broad spectrum for hospital acquired infections• Imipenem• Meropenem• Doripenem

– Group 3: MRSA active• Nil at present

Journal of Antimicrobial Chemotherapy (2003) 52, 538–542

Clinical Uses• Imipenem

– Lower Respiratory Tract infection– Urinary Tract Infection (uncomplicated or complicated)– Intra abdominal infection– Gynaecological infection– Bacterial septicemia– Bone & joint infection– Skin & soft tissue infection– Endocarditis– Polymicrobial infections

• Meropenem– Skin & soft tissue infection– Intra abdominal infection– Bacterial meningitis

• Ertapenem– Community acquired pneumonia requiring hospitalization

Carabpenemases: a problem in waiting ?David M Livermore & Neil Woodford

Current Opinion in Microbiology 2000; 3: 489 - 495

Natural resistance

Acquired resistance

Bush 2010 : Distribution of β lactamases according to function

Most Carbapenemases can HydrolyzeALL

Beta lactam antibiotics

Carbapenemases

• The most versatile family of -lactamases

• Two major groups based on the hydrolytic mechanism at the active site– Serine at the active site: class A and D– Zinc at the active site : class B

• All carbapenemases hydrolyze penicillins, extended spectrum cephalosporins, and carbapenems

Classification

Molecular Class

A B D

Functional Group

2f 3 2d

Active site Serine Zn++ Serine

Aztreonam Hydrolysis

+ - -

EDTA Inhibition

- + -

APBA Inhibition

+ - -

Mechanism of Resistance to Carbapenem

1. Cephalosporinase : Amp C & CTX- M+ Porin mutation = low level

resistance2. Carbapenemase: β lactamases that can hydrolyze carbapenem

Amber Class A: 9 familiesKPC, SME, NMC-A, IMI, PER, GES, SFO,

SFC, IBCAmber Class B: 6 families VIM, GIM, SIM, NDM, IMP, SPM

Amber Class D: 2 families OXA, PSE

Enzyme Ambler Class

Country Spectrum of activity Organisms

GESGuiana Extended spectrum

A French Guiana

Imipenem & extended spectrum cephalosporins

Ps.

SMESerratia marcesance enzyme

A USA Carbapenem, aztreonam but not 3rd gen cephalosporins

Serratia marcescens

NMC – A, IMINon metallo carbapenamse

A Europe Carbapenem, aztreonam but not 3rd gen cephalosporins

Enterobacter spp

KPCKleb pn. carbapenamase

A USA All β lactams Kleb. pneumoniae

OXA Oxacillin hydrolysing

D Scotland Carbapenems (weak) Acinetobacter, Ps.

Serine β lactamases:

Enzyme Ambler Class

Country Spectrum of activity Organisms

IMP (18)Imipenem Japan

B Japan All β lactams Ps., Acinetobacter

VIM (12)Verona

B Italy Pan R, may be S to aztreonam

Ps. , Acinetobacter

SPMSao Paulo

B Brazil Pan R Ps

GIM German

B Germany Pan R Ps.

SIM Souel

B South Korea

Pan R Acinetobacter, Ps.

NDM New Delhi

B India, UK Pan R Kleb pneu, E. coli

Metallo β lactamases (Zn at active site)

Lancet Infect Dis 2010; 10: 597–602 Published Online August 11, 2010

1985 1986 1990 1995 2000 2008 2010

Imipenem launched

Chromosomal R in Ps

IMP in Japan

VIM in Verona

KPC in USA

March of Carbapenemases

NDM 1

Clinical Microbiology and Infection, Volume 16 Number 12, December 2010

Castanheira M et al: Anti Agents Chem 2010SENTRY Program

Out of 39 strains collected from India in 200615 strains had NDM 1

10 strains carried OXA 48 variant2 strains carried VIM 6Multiple PFGE patterns

Location of BlaKPC gene

Why is CRE a public health emergency ?

• Significantly limits treatment options for life threatening infections

• No new drug for GNB in the pipeline

• Resistant mechanism easily transferable as it in now on a transposon

• Rapid Detection & effective infection control measures essential to control spread

Why is CRE spreading ?

• Resistance mechanism of a transposon

• Suboptimal methods of laboratory detection of isolates, large reservoir

• Continued antibiotic selection pressure

• Inadequate or incomplete institution of infection control measures

Who is infected with CRE ?

• Hospitalized patients with– Increased number of co morbid conditions– Frequent & prolonged hospitalization– Invasive devises– Antimicrobial selective pressure

• Previous Carbapenem use• Previous Metronidazole use

– CRE most frequently isolated in surgical wards from surgical drainage, bile , blood or urine

Recommendations for control

• Surveillance

• Infection control

• Laboratory detection

Surveillance

• Is CRE present in your facility ?– Review microbiology data for 6 to 12 months– If no,

• Conduct a point prevalence survey– Single round of AST in high risk patients

– If yes• Conduct AST on patients with epidemiological link

to CRE case

• Goal:– Identify undetected carriers of CRE

Infection ControlCDC’s recommendations

• Goal: Institute contact precautions to prevent patient to patient transmission

• Contact isolation– Disposable gloves & gowns available at each bedside– Alcohol based hand rub available & used– Environmental surfaces cleaned daily with aerosolized foam

quaternary ammonium compound– Disposable antibacterial wipes containing isopropanol &

quaternary ammonium compound for cleaning patient related items at least once a day

• Infection control team participated in daily round• Rectal swabs on admission & weekly

Infection control: add onsKochar S et al. Infect control & Hosp Epidemiol 2009; 30: 447 - 452

• ICU extensively cleaned: environment & pt care items• For All pts. culture positive for CRE,

– a copy of antibiogram placed in bedside records– Moved & gathered at one end of ICU– Nursing personnel also grouped

• Free standing dispensers for alcohol based hand rub available at bedside

• Disposable antibacterial wipes to clean environment at beginning of 12 hour shift and SOS

Laboratory DetectionClinical and Laboratory Standards Institute breakpoints: 2009 & 2010

Revised Break Points 2010

Agent MIC breakpoint (ug/ml) DD breakpoints (mm)

S MHT I R S MHT I R

IPM < 1

< 1

2-4 8

2

>16

>4

>16

>23

NA 14-15

20-22

<13

<19

MEM < 1

< 1

2-4 8

2

>16

>4

>22 >23

16-21 14-15 20-22

<13 <19

ERT < 1

< 0.25

2 4

0.5

>8

>1

> 22 >23

19-21 16-18 20-22

<15 <19

Screening for CRE

Screening for CRE carriage

Sample Select Differentiate TSB + carbapenem disk

CHROMagarESBL & KPC

Panagea T et al : Evaluation of CHROMagarTM KPC for the detection of carbapenemase-producing Enterobacteriaceae in rectal surveillance cultures.International JournalofAntimicrobialAgents xxx (2010) xxx–xxx

Randall LP et al: Evaluation of CHROMagar CTX, a novel medium for isolating CTX-M-ESBL-positive Enterobacteriaceae while inhibiting AmpC-producing strains. Journal of Antimicrobial Chemotherapy (2009) 63, 302–308

Test for Carbapenemase DetectionAnderson KF et al. Evaluation of methods to identify KPC in

enterobacteriaceae. JCM 2007; 45: 2723 – 2725.

Modified Hodge Test (MHT)

Carbapenem Inactivation Assay

Carbapenem Disk

Susceptible E. coli

Test Isolate

Double DiskPicao RC et al: MBL detection: Double Disk Synergy vs Combined Disk.

JCM 2008; 46: 2028 - 2037

Combined DiskDoi Y et al. Single disk method for detecting KPC by use of a

Boronic acid compound. JCM 2008; 46: 4083 - 4086

E testWalsh T et al. Evaluation of a new Etest for detecting MLB in routine

clinical testing. JCM 2002; 40: 2755 - 2759

Pasteran F et al. Controlling false positive results in MHT.. JCM 2010; 48: 1323 - 1332

Pasteran F et al. Controlling false positive results in MHT.. JCM 2010; 48: 1323 - 1332

Pasteran F et al. Controlling false positive results in MHT.. JCM 2010; 48: 1323 - 1332

False Positive

MASUDA ASSAY

Phenotypic Detection

Enzyme Inhibited by Cloxacillin Boronic acid EDTA/DPA

ESBL N N N

Amp C Y Y N

KPC N Y N

MBL N N Y

OXA N N N

Sensitivity & specificity of phenotypic methods

Test β lactamase Sensitivity Specificity

APBA KPC 100 98

APBA+

CLX

Amp C 80 100

DPA MBL 100 100

EDTA MBL 100 80

Modified Hodge

Carbapenemase 100 77

Genotypic detection of CREMendes RE et al: RT PCR for MBL

JCM 2007; 45: 544 - 547

Naaz T et al: Evaluation of a DNA Microarray, the Check-Points ESBL/KPC Array, for Rapid Detection of TEM, SHV, and CTX-M Extended-Spectrum β-Lactamases and KPC Carbapenemases. Anti Agents Chemother 2010; 54: 3086 - 3092

Detecting CRE

• Clinical CRE is tip of iceberg

• Asymptomatic carriage is common (faecal)

• Active Surveillance Test would help identify carriage

• Institution of contact precautions & monitoring of pt to pt transmission within ICU

• AST: When pt is transferred in from other hospitals

• AST: ? On discharge (medical tourism)

Guideline for phenotypic screening and confirmation of carbapenemasesin Enterobacteriaceae 2010Dutch Working Party on the Detection of Highly Resistant Microorganisms

Clinical isolates

Algorithm for disk diffusion synergy tests to detectCarbapenem Non Susceptible Enterobacteriaceae

APBA = aminophenyl boronic acid (β lactamase inhibitor)DPA = dipicolinic acid (metal chelating agent)

Epidemiological scale & stage of nationwide expansion of CNSE

Areas of Improvement

1. Ad hoc care ascertainment with existing laboratory capacity2. Standardization of detection & reporting3. Need for consistent capacity building of reference diagnostics4. Need for structured surveys to determine sensitivity & specificity of break points5. Need for harmonized typing tool/initiative6. Need for control data collection on dissemination & introduction of strains of public health importance7. Need for guidelines for graded approaches to infection control8. Antibiotic policy9. Treatment and clinical research10. Political commitment

Carry Home messages

• Carbapenemases in Enterobacteriaceae compromise our ability to effectively treat life threatening infections

• Pt to pt transmission can be halted by application of strict infection control measures

• Laboratory identification of infection or carriage must be paired with rapid implementation of Infection control interventions

• Ongoing Surveillance is essential

• Laboratory can help preserve Carbapenem antibiotics as very important resource for life threatening infections

• Susceptibility to Carbapenem must be determined accurately in the laboratory:– Wild type– ESBL producers– ESBL + omp mutation– CRE

Would respond to treatment withA carbapenem

We may not be able to stop the emergence of Super bugs

but we CAN