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

Abstract

Purpose: Acinetobacter baumannii has been identified as an opportunistic pathogen responsible for nosocomial infection with increasing trends. To identify the circulation of epidemic clones, enterobacterial repetitive intergenic consensus (ERIC)-PCR based genotyping patterns can be helpful. Repetitive sequences of gene found in A. baumannii are seen in non-coding fragment of the DNA, these sequences are variable in number and length which can be amplified in vitro using their sequence specific primers. Cluster of strains can be grouped in similar groups according to the diverse patterns determining genetic relatedness. Methods & Materials: This study was conducted in Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India (January-February 2021). A. baumannii isolates from different samples were collected from various wards and ICUs. Culture confirmation was done using MALDI-TOF MS. Total 22 A. baumannii isolates were collected, out of which, pleural fluid were (30%), CSF (27.5%), and the ascitic fluid (42.5%). Extracted bacterial DNAs were processed for ERIC-PCR fingerprinting using following primers F:5’-ATGTAGCTCCTGGGGATTCAC-3 and R:5’ AAGTAAGTGACTGGGGTGAGCG-3. Results obtained in the format of multiple band sizes and analyzed using Gel Analyzer Software. Results: Clonal diversity has been determined for 22 Acinetobacter baumannii, 15 different patterns were obtained from ERIC-PCR analysis including 2 patterns as common ERIC pattern and 13 patterns were unique. Most common ERIC pattern was designated as ERIC type-1and on the basis of relatively low frequency, ERIC patterns were designated as ERIC type 2, 3 and so on. ERIC type-1 was identified in 6 isolates and ERIC type-2 was identified in 3 different isolates. Similarities have been identified in 4 ERIC patterns i.e. between type-1 and 3. Low levels of similarities have been identified in type 4 and 5. Total 50% isolates representing ERIC type-1 pattern were from pleural fluid and 33.3% from Cerebrospinal fluid. Conclusion: The presence of different ERIC patterns categorized isolates into groups and implies that the spread of some of the circulating strains from a common source. Isolate with almost similar pattern indicates the emergence of diverging strain in the patient and environment. This information will also be helpful in identification of clones in different areas.