Characterization of carbapenem-resistant biofilm forming Acinetobacter baumannii isolates from clinical and...

Acinetobacter baumannii (A. baumannii) is an important nosocomial pathogen responsible for a wide range of human infections. The emergence of multidrug resistance (MDR) causes life-threatening nosocomial infections. Also, the formation of biofilm helps it survive on abiotic surfaces and is transferred through healthcare workers, thereby causing nosocomial infections. Hence, we study the current antibiotic resistance patterns and virulence factors in our clinical and colonizing isolates. A total of 92 isolates (44 colonizing and 48 clinical) of A. baumannii were included in the study. Antibiotic susceptibility testing was performed by VITEK 2. Biofilm formation was assessed by the tissue culture plate method. Polymerase chain reaction (PCR) for oxacillinases, MBLs and biofilm-associated genes were performed. Meropenem resistance was found in 42 (87.5%) of the clinical and 44 (97.7%) of the colonizing isolates. A strongly adherent biofilm was produced by 11 (22.91%) of the clinical and 12 (27.27%) of the colonizing isolates. Biofilm-associated genes, ompA, bap and csuE were present in 45 (93.7%), 47 (97.9%) and 44 (91.6%) of the clinical isolates, respectively and in all the colonizing isolates. bla_OXA23-like was more prevalent in colonizing than clinical isolates. bla_OXA-58-like and bla_OXA-24-like were present in very few isolates. The presence of metallo beta-lactamase (MBLs) was observed to be lower than oxacillinases. NDM1 was present in 15.29%, SIM in 27%, GIM in 14.11%, VIM in 32.9%, SPM in 5.8%, and IMP in 1.2% of the meropenem-resistant isolates. Carbapenem resistance (XDR) is increasing in A.baumannii. Biofilm formation is an important virulence factor responsible for its survival in the hospital environment and causes nosocomial infections. Biofilm-producing isolates were also found to be carbapenem-resistant. Strict disinfection procedures are to be followed to prevent its spread in the hospital.