Extended spectrum beta-lactamase and aminoglycoside modifying enzyme genes in multi drug resistant Gram-negative bacteria: A snapshot from a tertiary care centre

Muqtadir Malik; Mahadevan Kumar; Gurpreet Singh Bhalla; Kundan Tandel

doi:10.1016/j.mjafi.2023.09.007

Extended spectrum beta-lactamase and aminoglycoside modifying enzyme genes in multi drug resistant Gram-negative bacteria: A snapshot from a tertiary care centre

Med J Armed Forces India. 2024 Dec;80(Suppl 1):S223-S231. doi: 10.1016/j.mjafi.2023.09.007. Epub 2023 Nov 11.

Authors

Muqtadir Malik¹, Mahadevan Kumar², Gurpreet Singh Bhalla³, Kundan Tandel⁴

Affiliations

¹ Graded Specialist (Microbiology), INHS Asvini, Colaba, Mumbai, India.
² Professor (Microbiology), Bharati Vidyapeeth University Medical College, Pune, India.
³ Classified Specialist (Microbiology), Command Hospital (Southern Command), Pune, India.
⁴ Associate Professor, Department of Microbiology, Armed Forces Medical College, Pune, India.

PMID: 39734850
PMCID: PMC11670644 (available on 2025-12-01)
DOI: 10.1016/j.mjafi.2023.09.007

Abstract

Background: This study aims to enhance the existing knowledge of the prevalence of genes responsible for beta-lactam resistance and aminoglycoside resistance in gram negative organisms by molecular detection of extended spectrum beta-lactamase and aminoglycoside modifying enzymes in multidrug-resistant gram-negative bacteria.

Methods: Out of 864 gram-negative isolates, 710 were phenotypically identified as multidrug-resistant by antibiotic susceptibility testing. From the above isolates, 102 representative isolates as per sample size calculated were selected for further molecular studies. The presence of blaTEM, blaCTX-M blaSHV, and five AmpC genes was detected by real-time polymerase chain reaction (PCR). Conventional PCR was performed to detect seven aminoglycoside modifying enzyme genes namely aac(6')-Ib, aac(6')-Ic, aac(3)-Ia, aac(3)-Ib, aac(3)-IIa, ant(2'')-Ia, and ant(4'')-IIa.

Results: Most common multidrug-resistant isolate was Klebsiella pneumoniae (35%) followed by Escherichia coli (30%). Among the 102 selected isolates all harboured blaTEM gene, 71 (69.6%) harboured blaCTX-M gene and 48 (47%) blaSHV gene. Among the selected isolates 60% showed the presence of AmpC genes. Most common aminoglycosie modifying enzyme gene was AAC 6' Ib (51%) followed by ANT 2" Ia (36%).

Conclusion: This study suggests a wider use of molecular methods using specific PCR amplification of resistance genes. It would be beneficial to perform the molecular identification of antimicrobial resistance genes to effectively monitor and manage antibiotic resistance, administer appropriate antimicrobial medication, practice antimicrobial stewardship and improve hospital infection control procedures.

Keywords: Aminoglycoside; AmpC beta-lactamase; Extended spectrum beta-lactamase; Gram negative aerobic bacteria; Multiple antibacterial drug resistance.