Characterization of carbapenem resistance mechanisms inKlebsiella pneumoniaeandin vitrosynergy of the colistin–meropenem combination

Abstract

In this prospective study, consecutive isolates of Klebsiella pneumoniae were tested for different mechanisms of carbapenem resistance using the modified Hodge test (MHT), Rosco Neo-Sensitabs (ROSCO). Phenylalanine arginine beta-naphthylamide assay (PABN) inhibitor-based test was done on isolates in which the mechanism of resistance was not identifiable by the ROSCO. Among 105 selected isolates, carbapenemase production was noted in 100 (95%) by MHT and ROSCO showed 97 (92·4%) inhibition with dipicolinic acid signifying the production of MBL. PCR amplification was positive in 90 (86%) isolates for bla(NDM-1) and 46 (44%) isolates for bla(OXA-48). 54 (51%) isolates were positive for bla(CTX-M) and all belonged to bla(CTX-M) group 1. Isolates co produced bla(OXA-48) (31/105, 30%) and bla(CTX-M) (40/105, 38%) in combination with the carbapenemase (bla(NDM-1)) gene. Five colistin-resistant isolates were positive for bla(OXA-48). Eight isolates did not show inhibition with any of the inhibitor containing disks and found to be positive for bla(OXA-48). Isolates were tested for colistin-meropenem synergy and detection rate was higher by the checkerboard (48%) than E-test method (35%). Our study necessitates continuous surveillance to recognize the predominant machinery of resistance in a particular geographical region to formulate effective control measures.

In vitro evaluation of antibiotic synergy for carbapenem-resistant Klebsiella pneumoniae clinical isolates

“…For meropenem-colistin combination, increased percentage of synergism was found by MCB method (88%) as compared to Etest (82%). Krishnappa et al 20 also detected higher synergism by the MCB method (48%) than Etest (35%). Results by TKA method were significant on comparison with MCB and Etest.…”

Evaluation of Antibiotic Resistance Pattern and Efficacy of Modified Hodge Test for Detection of Carbapenem-Resistant Klebsiella pneumoniae Strains Isolated From Clinical Samples

“…14 In several other studies like that of Krishnappa et al and Shanmugam et al, the frequency of carbapenemase-producing cases were 82% (38/46) and 95%, respectively. 15,16 In another study in Brazil, 36 of the 44 carbapenem non-susceptible K. pneumoniae isolates were phenotypic carbapenemase producers as determined by the MHT. 17 In the studies conducted in Iran like that of Roudbari et al and Shokri et al, the prevalence of carbapenem-resistant K. pneumoniae were 87% and 7.1%, respectively.…”

A prospective evaluation of synergistic effect of sulbactam and tazobactam combination with meropenem or colistin against multidrug resistant Acinetobacter baumannii

“…In recent days the use of two different antibiotics in combination has been explored as a successful therapeutic option [16][17][18]. Sulbactam and tazobactam are an irreversible inhibitors of β-lactamase and they are given in combination with β-lactam antibiotics to inhibit β-lactamase [19].…”