Biofilm formation in drug-resistant Acinetobacter baumannii and Acinetobacter nosocomialis isolates obtained from a university hospital in Pelotas, RS, Brazil.

This study aimed to investigate the antibiotic resistance and biofilm formation of Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) complex isolates recovered from a university hospital in Pelotas, RS, Brazil. The species were confirmed using gyrB multiplex and blaOXA-51-like genes PCR. The presence of the bfmRS virulence gene was evaluated by the PCR, and the isolates were classified based on their biofilm-forming ability on polystyrene (PO) and glass surfaces (TM). Out of 50 ACB complex isolates evaluated, 41 were identified as A. baumannii and 9 as A. nosocomialis. The bfmRS gene was detected in 97.6% (40/41) of A. baumannii and 33.3% (3/9) of A. nosocomialis species. Forty-nine isolates exhibited a multi-drug resistant (MDR) profile, while one A. nosocomialis isolate presented an extended-drug resistant (XDR) profile. All isolates were able of forming biofilms on PO surfaces, and 98% (49/50) on TM surfaces. A significant correlation was observed between biofilm production on PO and TM surfaces (p < 0.05). However, no correlation was found between biofilms forming and the presence of bfmRS gene or displaying a certain antibiotic resistance profile. In conclusion, A. baumannii and A. nosocomialis are frequent species causing nosocomial infections in a hospital in Pelotas, RS, Brazil, and both are capable of forming biofilms.