Prevalence of Class 2 Integrons in Multidrug-Resistant Acinetobacter Baumannii in Toxicological ICU Patients in Tehran

Acinetobacter baumannii is an important opportunistic pathogen which causes complications in hospitalized patients, especially those in ICU. The aim of this study was to determine the frequency of class 1 and 2 integrons in multi-drug resistance A. baumannii and to investigate the association between the presence of integrons and antibiotic resistance patterns. A total of 40 A. baumannii strains were isolated from 372 ICU patients from June to Oct 2012. A. baumannii was detected in 50% of tracheal cultures, 15% in blood, 15% in urine samples, and 22.5% in other locations. In accordance with CLSI 2011, 12 antibiotics were used through disc diffusion method. Existence of integron classes was investigated by PCR assay with the amplification of integrase genes. The most effective antibiotic against Acinetobacter baumannii was polymyxin B with 100% susceptibility, followed by meropenem, piperacillin, cotrimoxazole, ceftazidime with 100% resistance; this was followed by ciprofloxacin 97.5%, tetracycline, 92.5%, imipenem 62.5%, and gentamicin 60% resistance. The presence of integron class 1 was 7.5%, class 2 was 67.5%, and non-integron was 20%. The association between multidrug resistance and class 2 integron was not statistically significant. Other factors accounting for the lack of significance of the findings may be the impact of other resistance determinants such as transposons or plasmids, not investigated in the current study. Considering the increasing trend of MDR infections among ICU patients with critical problems in follow up, the use of appropriate infection control strategy and a regular surveillance system is necessary in our hospital.