Carbapenamases Facts and Diagnosis
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CARBAPENAMASESFacts, Controversies, Detection
Number of agents approved
Bars represent number of new antimicrobial agents approved by the FDA during the period listed.
Infectious Diseases Society of America. Bad Bugs, No Drugs. July 2004; Spellberg B et al. Clin Infect Dis. 2004;38:1279-1286;
New antimicrobial agents. Antimicrob Agents Chemother. 2006;50:1912
Bush 2010 : Distribution of β lactamases according to function
Most Carbapenemases can Hydrolyze
Beta lactam antibiotics
1. Cephalosporinase : Amp C & CTX- M
+ Porin mutation = low level resistance
2. Carbapenemase: βlactamases that can hydrolyze carbapenems
Amber Class A: 9 families
KPC, SME, NMC-A, IMI, PER, GES, SFO, SFC, IBC
Amber Class B: 6 families
VIM, GIM, SIM, NDM, IMP, SPM
Amber Class D: 2 families
Metallo β lactamases (Zn at active site)
Clinical and Laboratory Standards Institute breakpoints: 2009 & 2010
Revised Break Points 2010
Modified Hodge Test for Carbapenemase Detection in Enterobacteriaceae
1)Some isolates demonstrate low-level carbapenem resistance
2) Some automated systems fail to detect low-level resistance
The Modified Hodge Test is a phenotypic confirmatory test for “Carapnemase” activity and is indicated when there is a positive screening test and resistance to one or more agents in cephalosporin subclass III (i.e., cefoperazone, cefotaxime, ceftazidime, ceftizoxime, and ceftriaxone) Be aware that imipenem disk tests perform poorly as a screen for carbapenemases.
Procedure described by Lee et al. CMI, 7, 88-102. 2001.
Modified Hodge Test (MHT)
Carbapenem Inactivation Assay
Lawn of E. coli ATCC 25922
1:10 dilution of a
0.5 McFarland suspension
Described by Lee et al. CMI, 7, 88-102. 2001.
Three Enterobacteriaceae isolates carrying a newly described resistance mechanism, the New Delhi metallo-beta-lactamase (NDM-1) , were identified from three U.S. states at the CDC antimicrobial susceptibility laboratory. This is the first report of NDM-1 in the United States, and the first report of metallo-beta-lactamase carriage among Enterobacteriaceae in the United States
An international organization dedicated to curbing antibiotic resistance
Chapters exist currently in several Asian countries: Australia, China, India, Nepal, Pakistan, Philippines, South Korea, Taiwan, Vietnam
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