Integron-associated antimicrobial resistance in isolates of members of Enterobacteriaceae causing community-acquired urinary infections

Abstract

The present study investigated 73 isolates of Enterobacteriaceae obtained from urine samples of outpatients for the presence of integrons and analysed the association between integrons and antimicrobial susceptibility. Resistance to one or two antibiotics belonging to different classes was found in 28 (38.4%) of the isolates, resistance to three or more antimicrobial agents with different mechanism of action, i.e. multidrug resistance in 37 (50.7%), while 8 (10.9%) were fully susceptible. The presence of integrons was shown in 13 (17.8%) of the strains tested: 9 (12.3%) carried a class 1 integron, 2 (2.7%) carried a class 2 integron, and 2 (2.7%) had both class 1 and class 2 integrons. Class 1 integron was clearly predominant, since 11 (84.6%) of 13 integron-positive isolates carried this class. No class 3 integron-positive isolates were detected. The association between the presence of an integron and multidrug resistance was highly significant (p<0.001). Integronpositive isolates were also more likely to be resistant to amoxicillin-clavulanic acid, co-trimoxazole, chloramphenicol, ciprofloxacin, norfloxacin, nalidixic acid, tetracycline and doxycycline. Five strains (45.5%) with class 1 integron were positive for the mercury resistance gene, merA, indicating the role of Tn21 transposon in dissemination of integrons within the samples studied. Key words: Integrons, antimicrobial resistance, Enterobacteriaceae, urinary tract infection