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Abstract Background Acinetobacter baumannii strains with multiple antimicrobial resistance are primarily known as opportunistic nosocomial bacteria but they may also be regarded as emerging bacterial contaminants of food samples of animal origin. Here we aimed to study the molecular characteristics of the A. baumanni strains isolated from raw meat samples. Methods A total of 22 A. baumanni strains were isolated from 126 animal meat samples and were genotyped by ERIC-PCR method and by PCR detection of their virulence and antimicrobial resistance determinants. A. baumannii strains with 80% and more similarities were considered as one cluster. Results Sixteen different genetic clusters were found amongst the 22 A. baumanni strains. Of the 22 strains, 12 (54.54%) had similar genetic cluster. A. baumannii strains exhibited the highest percentage of resistance against tetracycline (90.90%), trimethoprim (59.09%), cotrimoxazole (54.54%) and gentamicin (50.00%). TetA (81.81%), tetB (72.72%), dfrA1 (63.63%), aac(3)-IV (63.63%), sul1 (63.63%) and aadA1 (45.45%) were the most commonly detected antibiotic resistance genes. FimH (81.81%), afa/draBC (63.63%), csgA (63.63%), cnf1 (59.09%), cnf2 (54.54%) and iutA (50.00%) were the most commonly detected virulence factors. A. baumannii strains isolated from the chicken meat samples had the highest similarities in the genetic cluster. Conclusions A. baumannii strains with similar genetic cluster (ERIC-Type) had the same prevalence of antibiotic resistance, antibiotic resistance genes and virulence factors. Genetic cluster of the A. baumannii strains is the main factor affected the similarities in the genotypic and phenotypic properties of the A. baumannii strains.

Introduction: Acinetobacter baumannii is a gram-negative coccobacill that has a great distribution in the nature and is considered as one of the important causes of hospital infections. Due to the antibiotic resistances in this bacterium several problems in the successful treatment of patients and subsequently their mortality have been occurred. The present study was carried out in order to detect the most prevalent antibiotic resistance genes in Acinetobacter baumannii strains isolated from the hospital infections. Materials and methods: This descriptive study was carried out on 121 strains of Acinetobacter baumannii isolated from clinical samples of two hospitals of Tehran city. After identifying isolates using the biochemical tests, the antibiotic resistance pattern of them was done using the disk diffusion and molecular (in order to identify the antibiotic resistance genes) methods. Results: Of 121 strains of Acinetobacter baumannii isolated from infectious samples, the most commonly detected antibiotic resistance was against tetracycline and the most sensitivity was achieved against chloramphenicol, nitrofurantoin and meropenem by distribution of 1.65 %. The distribution of dfrA1, tet(A), aac(3)-IV, sul1, tet(B), aadA1, qnr, CITM, blaSHV, sim, vim, oxa-58-like. Oxa-24-like, imp, oxa-51-like, oxa-23-like, cat1 and cmlA were 79 (65.27 %), 71 (58.67 %), 68 (56.19 %), 67 (55.37 %), 44 (36.36 %), 41 (33.88 %), 29 (23.96 %), 28 (23.14%), 24 (19.83 %), 17 (14.04 %), 16 (13.22 %), 14 (11.57 %), 12 (9.91 %), 10 (8.26 %), 9 (7.43 %), 8 (6.61 %), 5 (4.13 %) and 3 (2.47 %), respectively. Discussion and conclusion: Multiple antibiotic resistance in studied isolates the use of molecular techniques in the antibiogram test to select the most effective antibiotic treatment of infections and the importance of continued antibiotic surveillance that will provide succession in the efforts of infection control programs for the future.