Co-expression of 16S rRNA Methyltransferase and Carbapenemase in Multidrug Resistant Gram Negative Bacteria

Abstract

Introduction: The drug resistance caused by bacteria has complicated the fight against the infectious diseases and recovery of the patients from the diseases. Multiple mode of drug resistant mechanisms including epigenetic and enzymatic mode have been involved in the genesis of drug resistance leaving only fewer antibiotics for the treatment. Studies has shown the presence of 16S methyltransferase which is associated with carbapenem drug resistance. Early detection of different multimode of bacterial drug resistance helps in reducing the dissemination rate and treatment failures. Aim: To detect the genes related to the methylation mode of bacterial drug resistant mechanism including armA (aminoglycoside resistance methylase), rmtA, rmtB, rmtC and rmtD (rmt-RNA methyltrasferase) as well as genes OXA-48 (Oxacillinase), VIM (Verona intergron metallo-β lactamase) and KPC (Klebsiella pneumoniae carbapenemase) in the production of carbapenemases and also to identify the co-expression of these genes in the gram negative bacterial isolates. Materials and Methods: Prospective study was conducted through application of multiplex Polymerase Chain Reaction (PCR) for detection of 16S methyltransferase genes including armA, rmtA, rmtB, rmtC and rmtD and carbpenemase VIM, KPC and OXA-48 genes, respectively. A total of 200 multidrug resistant gram negative bacilli were evaluated for presence of these genes. The antibiotic sensitivity was evaluated using Kirby-Bauer disc diffusion method. Results: The gram negative bacteria which were isolated includes Acinetobacter spp. 20, E.coli-85, Klebsiella spp.-55 and Pseudomonas aeruginosa-40 from several specimens such as urine, endotracheal tube-secretion, wound swab, sputum, pus etc. A total of 121 (61%) of the bacterial isolates were resistant to either gentamicin or amikacin and netilimycin and 50 (25%) bacterial isolates were resistant to either imipenem or carbapenem. A total of 48 (24%) isolates were resistant to both aminoglycosides and carbapenems. The 16S methyltransferase genes including armA gene was detected in 16 isolates, rmtB in 15 isolates, rmtC in 10 isolates and rmtD detected in 13 isolates The carbapenem genes detected including VIM in 20 isolates, OXA-48 in 25 isolates and KPC was detected in 13 bacterial isolates. Co-expression of both methyltransferase and carbapenemase were detected in nine isolates. Conclusion: The presence of multiple mode of bacterial drug resistance mechanisms including epigenetic and enzymatic modes have been found to be associated with resistance to different classes of antibiotics. The application of multiplex PCR helps in detection of multiple genes involved in bacterial drug resistance and helps in prevention of rapid spread of bacterial drug resistance and prevention of overuse of antibiotics.

Keywords

• bacterial drug resistance
• carbapenem
• methylase
• polymerase chain reaction