Detection of Carbapenemase Producing Gram-negative Bacteria at a Tertiary Care Hospital: A Cross-sectional Study

Abstract

Introduction: Gram-negative bacteria have developed a broad spectrum of resistance due to antibiotic degradation enzymes, including Extended-spectrum Beta-lactamases (ESBL), AmpC β-lactamases, and carbapenemases. Carbapenemase- producing organisms, such as Escherichia coli, Klebsiella species, Acinetobacter species, and Pseudomonas species, have become one of the most important causes of nosocomial and community-acquired infections. Aim: To identify carbapenemase-producing organisms among Multidrug-resistant (MDR) clinical isolates and detect Metallo β-Lactam Carbapenemases (MBL). Materials and Methods: The present study is a cross-sectional study that included 1266 clinical samples from patients visiting the Department of Microbiology, Ranagaraya Medical College, Kakinada, Andhra Pradesh, India. from July 2022 to December 2022. The samples were processed using the standard culture and antimicrobial susceptibility test, employing the Kirby-Bauer Disk Diffusion method. The present study included organisms that were resistant to either imipenem or meropenem. Carbapenemases were detected using the Modified Hodge test (MHT), and MBL carbapenemases were detected using the Imipenem Ethylene Diamine Tetraacetic acid (EDTA) Double Disk Test (DDT) following the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Descriptive statistics were performed on the collected data. Results: The study samples comprised 842 (66.5%) Gram- negative isolates and 424 (33.5%) Gram-positive isolates. Among the Gram-negative isolates, 80 (9.5%) were carbapenem- resistant, of which MHT showed 56 (70%) positive isolates (carbapenemase-producing) and 24 (30%) negative isolates. Imipenem-EDTA DDT showed 50 (62.5%) positive isolates (MBL-producing) and 30 (37.5%) negative isolates. Conclusion: Carbapenemase production in Gram-negative organisms has reduced the clinical utility of the carbapenem group of drugs, posing a major challenge in the treatment of severe infections. In summary, the majority of carbapenem-resistant isolates in the present study were from the Enterobacteriaceae family. These isolates were subjected carbapenem-resistant isolates to MHT and DDT tests to identify carbapenemase and metallo-beta-lactamase-producing strains that were resistant to a wide spectrum of antibiotics. The present study enables the early detection of these MDR strains, ensuring appropriate management.