blaOXA-51-Negative Acinetobacter calcoaceticus-baumannii Complex as a Cause of Human Infection in Peru

Background: Common identification techniques do not differentiate among members of the Acinetobacter calcoaceticus-baumannii (ACB) complex, and the presence of non-baumannii Acinetobacter is often misinterpreted. The bla OXA-51 gene is located within the chromosome of Acinetobacter baumannii. Despite its plasmid dissemination to other members of the genus, it may be considered in initial species screening. Thus, this study aimed to determine the presence of bla OXA-51-negative Acinetobacter spp. as a cause of infection in Peru. Methods: Two hundred ninety-eight ACB complex isolates from different regions of Peru were isolated between January 2018 and March 2024. Of these, 272 and 25 were confirmed as hospital-acquired and community infections, respectively. The presence of bla OXA-51 was determined by polymerase chain reaction, and the susceptibility levels to 12 antimicrobial agents were determined. Results: The results showed that 38 (12.7%) isolates were bla OXA-51-negative. These isolates were frequent among community infections (13/25, p < 0.0001), often causing urine infections. They showed significantly lower levels of resistance to almost all antimicrobial agents tested, and most of them were recovered from regions outside metropolitan Lima. Conclusion: A relevant number of infections by non-baumannii Acinetobacter species in Peru is suggested, highlighting the need for systematic identification of these species in the country. Keywords: Acinetobacter spp.; OXA-51; antibiotic resistance; community-acquired infection; hospital-acquired infection.