Plasmid distribution & antimicrobial susceptibility patterns of Acinetobacter genospecies from healthy skin of a tribal population in western India.

Background & Objective: Acinetobacter spp., the only Gram negative commensal found on human skin are emerging nosocomial pathogens, and are rapidly developing multiple drug resistance. Most studies in India and over the world are on clinical and environmental Acinetobacter isolates. The present investigation was undertaken to study plasmid distribution and antibiotic resistance profile of Acinetobacter genospecies isolated from healthy human skin of a tribal population from western India.

Methods: One hundred and eighteen strains of Acinetobacter spp. were isolated from healthy human skin and biochemically classified into nine genospecies. Plasmid profiles were determined using four standard methods with minor modifications and by a commercial kit. Molecular weights were determined by comparison with standard plasmids pUC19, pBR322, RP4 and molecular weight marker, V517. Antimicrobial susceptibility patterns of Acinetobacter genospecies to 30 antibiotics belonging to different groups was determined using Kirby Bauer method.

Results: All isolates, except two showed a maximum of three plasmids with molecular size 1.5 to 40 kb. Five different plasmid types were observed. Only eight strains had one or two stably maintained low molecular weight plasmids in addition to 40 kb plasmid seen in most of the strains. Quinolones and aminoglycosides were most active group followed by, cephalosporins and beta lactams.

Interpretation & Conclusion: Acinetobacter spp. isolated from the tribal skin flora had low number of plasmids as compared to clinical and environmental isolates. Acinetobacter spp. harbouring low molecular weight plasmids were found to be sensitive to most of the antibiotics tested suggesting these might be coding for some other novel properties or may be cryptic, whereas, those having 40 kb plasmid showed intermediate to low level resistance to some antibiotics.