Co-occurrence of Carbapenemase Genes, Disinfectant Resistance Determinants, and Class 1 Integrons in Acinetobacter spp. Isolated from Bloodstream Infections in Critical Care Units

Acinetobacter spp. represents critical opportunistic pathogens driving severe bloodstream infections (BSIs) in intensive care unit (ICU) and neonatal intensive care unit (NICU) settings. The convergence of carbapenem resistance and emerging biocide tolerance, often mediated by mobile genetic elements, has intensified concerns regarding co-selection and persistence in clinical environments. A total of 90 molecularly confirmed Acinetobacter isolates (ICU = 44; NICU = 46) from bloodstream infections were analyzed. Antimicrobial susceptibility was determined using the Kirby–Bauer disk diffusion method in accordance with CLSI M100 (2024) guidelines and extended-spectrum β-lactamase production was assessed by combined disc diffusion. Polymerase chain reaction (PCR) was employed to detect carbapenemase genes (bla _VIM , bla _NDM , bla _IMP , bla _OXA-23 , bla _OXA-58 ), biocide resistance determinants ( qacE , qac Δ E1 ), and the class 1 integron-integrase gene ( intI1 ). Multidrug-resistant (MDR) and extensively drug-resistant (XDR) phenotypes were identified in 71.1% (64/90) and 22.2% (20/90) of isolates, respectively. High resistance (>71%) was observed against meropenem and cephalosporins, whereas colistin (58.8%, 53/90) and amikacin (47.8%, 43/90) showed moderate susceptibility. The most prevalent genotypes were qac Δ E1 (76.6%, 69/90) and bla _VIM (56.6%, 51/90). Statistical and network analyses revealed significant correlations between biocide and carbapenemase genes, identifying IntI1 as a primary driver of co-resistance. The findings indicate a significant co-occurrence of carbapenemase genes, biocide resistance determinants, and class 1 integrons among Acinobacter spp. isolates. These associations suggest that mobile genetic elements may contribute to the dissemination of resistance traits.