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Saeed Khoshnood,1,2 Mohammad Savari,1,2 Effat Abbasi Montazeri,1,2 Ahmad Farajzadeh Sheikh1,2 1Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 2Department of Microbiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IranCorrespondence: Ahmad Farajzadeh SheikhInfectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Khuzestan 61357-15794, IranTel +98 9161133491Fax +98 61 3333 2036Email farajzadehah@gmail.comIntroduction: Acinetobacter baumannii is an opportunistic pathogen responsible for nosocomial infections. The emergence of colistin-resistant A. baumannii is a significant threat to public health. The aim of this study was to investigate the molecular characterization and genotyping of clinical A. baumannii isolates in Southwestern Iran.Methods: A total of 70 A. baumannii isolates were collected from patients admitted to Imam Khomeini Hospital in Ahvaz, Southwestern Iran. Minimum inhibitory concentration test was conducted by using Vitek 2 system. The presence of biofilm-forming genes and colistin resistance-related genes were evaluated by PCR. The isolates were also examined for their biofilm formation ability and the expression of pmrA and pmrB genes. Finally, multilocus sequence typing (MLST) and PCR-based sequence group were used to determine the genetic relationships of the isolates.Results: Overall, 61 (87.1%) and 9 (12.8%) isolates were multidrug-resistant (MDR) and extensively drug-resistant (XDR), respectively. Colistin and tigecycline with 2 (2.8%) and 32 (45.7%) resistance rates had the highest effect. Among all the isolates, 55 (78.5%), 7 (10%), and 3 (4.3%) were strong, moderate, and weak biofilm producers, respectively. The frequency rates of biofilm-related genes were 64 (91.4%), 70 (100%), 56 (80%), and 22 (31.42%) for bap, ompA, csuE, and blaPER1, respectively. Overexpression of pmrA and pmrB genes was observed in two colistin-resistance isolates, but the expression of these genes did not change in colistin-sensitive isolates. Additionally, 37 (52.8%) and 8 (11.4%) isolates belonged to groups 1 (ICII) and 2 (IC I), respectively. MLST analysis revealed a total of nine different sequence types that six isolates belonged to clonal complex 92 (corresponding to ST801, ST118, ST138, ST 421, and ST735). Other isolates were belonging to ST133 and ST216, and two colistin-resistant (Ab4 and Ab41) isolates were belonging to ST387 and ST1812.Conclusion: The present study revealed the presence of MDR and XDR A. baumannii isolates harboring biofilm genes and emergence of colistin-resistant isolates in Southwestern Iran. These isolates had high diversity, which was affirmed by typing techniques. The control measures and regular surveillance are urgently needed to preclude the spread of these isolates.Keywords: Acinetobacter baumannii, drug resistance, colistin, MLST, clonal complex

Aghil Bahramian,1,2 Saeed Khoshnood,3,4 Aref Shariati,5 Farahnoosh Doustdar,2 Alireza Salimi Chirani2 Mohsen Heidary5,6 1Infectious Diseases and Tropical Medicine Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; 2Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; 3Department of Microbiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 4Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 5Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran; 6Student Research Committee, School of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran Introduction: Pseudomonas aeruginosa is the most common opportunistic pathogen associated with a broad range of infections, including cystic fibrosis, ocular, otitis media, and burn infections. The aim of this study was to show the frequency of the pilS2 gene, and its association with P. aeruginosa plasmid pKLC102 and PAPI-1 pathogenicity island among P. aeruginosa strains.Methods: The samples were collected from patients with cystic fibrosis, ocular, otitis media, and burn infections between January 2016 and November 2017. DNA was extracted using the DNA extraction kit and was used for PCR assay. PCR with 4 primer-pairs including 976 F/PAPI-1R, 4542 F/intF, SojR/4541 F, and intF/sojR was performed to identify PAPI-1. pKLC102 was detected using three other primer-pairs including cp10F/ cp10R, cp44F/cp44R, and cp97F/cp97R.Results: A total of 112 P. aeruginosa isolates were collected from patients with cystic fibrosis (36), burn (20), otitis media (26), and ocular (30) infections. The results of PCR showed that pilS2 gene was identified in 96 (85%) strains. PAPI-1–attB integration was detected among 38 (33.9%) isolates and the circular form of PAPI-1 detected among 17 (14%) isolates. In addition, 79 (70.5%) strains were found to be positive for pKLC102.Conclusion: We found that the majority of the isolates may be susceptible to transfer this significant island and the related element pKLC102 into recipient isolates lacking the island owing to high association of the PilS2 pilus with the islands in the studied strains. It is anticipated that strains isolated from burn and eye with the highest rate of PilS2, PAPI-1, and pKLC102 association have a high level of antibiotic resistance. Keywords: Pseudomonas aeruginosa, pilS2, cystic fibrosis, pKLC102, PAPI-1