Detection of efflux pump in multidrug resistant acinetobacter Species using Naphthyl-Methyl-Piperazine

Abstract

Acinetobacter, Gram negative bacterium, has proven to be recently important to research due to multidrug resistance. Multidrug resistance is directed against antibiotics like Aminoglycosides, Carbapenems, Cephalosporins, Quinolones etc. The presence of efflux pump, primarily the Resistance-Nodulation-Cell Division (RND) type, is an active transport mechanism which allows it to efficiently reduce antibiotic levels within the cell. 1-(1-naphtylmethyl)-piperazine (NMP) is an efflux pump inhibitor (EPI) which mechanically inhibits the efflux pump in bacteria resulting in increased concentration of antibiotic intracellularly, thereby killing the cell. Objectives: To detect the efflux pumps phenotypically using NMP and to establish the cut-off zone diameter to detect efflux pump in Acinetobacter species. Materials and Methods: Acinetobacter species were isolated from patient samples using conventional techniques of inoculation, identification and antibiotic susceptibility testing. The efflux pump was detected phenotypically by disc diffusion method on Mueller Hinton agar with NMP and chloramphenicol, tetracycline discs as substrates. The zone diameters were recorded & values compared using t-test. Tipping analysis was done to determine the mean zone difference to identify the presence of efflux pump. Results and Conclusion: 61% of the Acinetobacter species were multidrug resistant of which 63% had efflux pump as detected by chloramphenicol substrate which is better than Tetracycline (p<0.05). A difference of 5 mm in the zone diameter can be used to detect efflux pump. The gene encoding for the efflux pump -AdeFGH was present in 72% of the isolates. NMP can be a potential adjuvant with common antibiotics to treat MDR Acinetobacter infections.