Carbapenemases

Abstract

Carbapenems are usually regarded as the last treatment option for serious infections caused by Gram-negative and Gram-positive microorganisms. Although they are stable to hydrolysis by most β-lactamases, their usage as the last resort antbiotics was seriously compromised by the appearance of carbapenemhydrolyzing enzymes called carbapenemases. These enzymes are produced mostly by Enterobacteriaceae and Gram-negative nonfermentative bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii. True carbapenemases belonging to Ambler molecular classes A, B, and D are often encoded by genes embedded in mobile genetic elements like plasmids, integrons, and transposons, which often harbor multiple resistance determinants limiting further the treatment options. At present, large number of nosocomial and community-acquired infections caused by worldwide spread of carbapenem-resistant Gram-negative bacteria have become a major public health problem. Although polymyxins remain active, in vitro reports of benefits of combination schemes favor this strategy against carbapenemaseproducing Gram-negative bacilli.

Comparison between Multiplex PCR and Phenotypic Detection Methods for Identifying AmpC B-lactamases Among Clinical Isolates of Enterobacteriaceae in Zagazig University Hospitals, Egypt

“…PAmpC positive isolates in the present study were sensitive to meropenem, imipenem, and Tigecycline 89.5%, 84.2% and 68.4%. These results disagreed with other study conducted by Bedenić et al [27] reported higher susceptibility to Tigecycline and carbapenems (100%). Another study by Manoharan et al [21] reported higher sensitivity 99% for Tigecycline and 97% for imipenem and meropenem.…”

Phenotypic Detection of Carbapenemase Production in Carbapenem-Resistant Enterobacteriaceae by Modified Hodge Test and Modified Strip Carba NP Test

“…Although they are stable to hydrolysis by most β-lactamases, their usage as the last resort antibiotics was seriously compromised by the appearance of new class of bacterial enzymes capable of inactivating carbapenems, called as carbapenemases. 28 Resistance to carbapenem antimicrobials is either due to expression of carbapenemases or due to combined mechanisms of resistance (overexpression of broad-spectrum β-lactamases together with efflux pumps, impermeability); however, carbapenemases production represents the most important mechanism of resistance in Enterobacteriaceae, associated with multi-or pan-drug resistance.…”

Surveillance and prevalence of antimicrobial resistant bacteria from public settings within urban built environments: Challenges and opportunities for hygiene and infection control

“…The Ambler classification system has classified carbapenemases into four groups, three of which (A, B and D) belong to Enterobacteriaceae ( Hall and Barlow, 2005 ). A Class C carbapenemases have also been described; however, they are not considered true carbapenemases as they have a low enzyme’s catalytic efficiency and a permeability defect, which only gives them a slight reduction in susceptibility to carbapenems ( Bedenić and Sardelić, 2018 ). Class A carbapenemases are associated with K. pneumoniae (KPC) as are the less common non-metallocarbapenemase type A (NMC-A) and SME enzymes; Class B carbapenemases are associated with metallo-β-lactamases (MBL) including New Delhi metallo-β-lactamases (NDM), the IMP family of carbapenemases, and the Verona integron–encoded metallo-β-lactamases (VIM).…”