Clonal relationship among Acinetobacter baumannii isolates from different clinical specimens by ERIC-PCR

Acinetobacter baumannii (A. baumannii) is a major cause of nosocomial infections, and molecular typing is important for understanding the circulation of epidemic clones in hospital settings. This study aimed to determine the clonal diversity and circulation of Acinetobacter baumannii isolates using enterobacterial repetitive intergenic consensus (ERIC)-PCR-based genotyping.

This cross-sectional study analyzed 119 Acinetobacter baumannii isolates recovered from clinical specimens, including blood, sputum, CSF, ascitic fluid, pleural fluid and urine collected from patients admitted to different inpatient departments. Isolates were identified using standard microbiological and biochemical methods and confirmed by using MALDI-TOF MS. Genomic DNA extracted from culture isolates was subjected to ERIC-PCR to assess clonal relatedness and identify circulating genotypes.

ERIC-PCR analysis revealed high clonal diversity among the 119 isolates, generating 82 distinct genotypic patterns, including 16 common (shared by 53 samples) and 66 unique ERIC patterns. The most prevalent patterns were designated ERIC type 1 and ERIC type 2, identified in 7 and 6 isolates, respectively, indicating limited clustering alongside widespread genetic heterogeneity. Although isolates within the same ERIC clusters showed genetic relatedness, variations in their antibiogram profiles were observed, suggesting ongoing divergence among circulating strains.

The presence of multiple ERIC patterns demonstrates substantial genetic diversity among Acinetobacter baumannii isolates, while shared patterns suggest the circulation of genetically related clones within the hospital environment. These findings highlight the value of ERIC-PCR in assessing clonal relatedness and supporting molecular surveillance and monitoring the emergence of divergent strains.