Phenotypic and genotypic detection of carbapenemase production among gram negative bacteria isolated from hospital acquired infections

• Published in: Saudi medical journal Vol. 43; no. 3; pp. 236 - 243
• Main Authors: Vamsi, Sreeja K, Moorthy, Rama S, Hemiliamma, Mary N, Chandra Reddy, Rama B, Chanderakant, Deepak J, Sirikonda, Shravani
• Format: Journal Article
• Language: English
• Published: Saudi Arabia Saudi Medical Journal 01-03-2022; Prince Sultan Military Medical City (PSMMC)
• Subjects: Anti-Bacterial Agents - pharmacology; Antibiotics; Bacterial Proteins - genetics; Beta lactamases; beta-Lactamases - genetics; Causes of; Cross infection; Drug resistance in microorganisms; Genes; Genetic aspects; Genotype & phenotype; Gram-negative bacteria; Gram-Negative Bacteria - genetics; Health aspects; Hospitals; Humans; Identification and classification; Immune system; Microbial Sensitivity Tests; Nosocomial infections; Original; Penicillin; Prospective Studies; India; beta-lactamases; carbapenems; drug resistance; microbial; antibacterial agents
• DOI: 10.15537/smj.2022.43.3.20210809
• EISSN: 1658-3175
• ISSN: 0379-5284

To identify the carbapenemase producing Gram-negative bacteria (GNB) by phenotypic methods and to confirm the presence of resistant genes using real-time polymerase chain reaction (PCR).
This was a prospective study carried out at the Department of Microbiology, Sri Venkata Sai Medical College and Hospital, Mahabubnagar, India, from March 2018-2021. All samples were screened for carbapenem resistance by disc diffusion method and the VITEK
2 compact system (bioMérieux, France). Detection of carbapenemase was carried out using RAPIDEC
CARBA NP test (Biomeriux Private Limited, South Delhi, India), screening for metallo-β-lactamases (MBL) was carried out by double disk synergy test (DDST), and genotypic characterization by real-time PCR.
Among the 1093 Gram-negative bacilli identified, 220 (17.0%) were resistant to carbapenems by both tested methods. Carbapenemase detection using the RAPIDEC
CARBA NP test indicated that 207 (94.0%) were carbapenemase producers, of which 189 (91.2%) were MBL producers. The most common carbapenemase genes identified were New Delhi metallo-β-lactamase (NDM; 47.3%), followed by the co-existence of genes in combination of NDM, with Verona integron-mediated metallo-β-lactamase (VIM; 39.6%), VIM and oxacillin hydrolyzing enzymes-48 (OXA-48; 4.3%), and OXA-48 (1.4%).No gene of active on imipenem,
carbapenemase, VIM, or OXA-48 alone was detected.
This study suggests routine carbapenem resistance testing among multi-drug resistant-GNBs, as most of these infections occur in hospitals. In addition, there is a possibility that these highly antibiotic-resistant genes could spread to other bacteria resulting in further dissemination.