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-A. 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 nine 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 multidrug-resistant (MDR) profile, while one A. nosocomialis isolate presented an extensively 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 the 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.