Investigation of Integron-Associated Resistance Gene Cassettes in Urinary Isolates of Klebsiella pneumoniae in Yasuj, Southwestern Iran During 2015-16

Growing antibiotic resistance among urinary opportunistic pathogens such as Klebsiella pneumoniae (K. pneumonia) has created a worrisome condition in the treatment of the Urinary Tract Infections (UTIs) in recent years. Integrons play a significant role in the dissemination of antibiotic resistance genes. The present study was conducted to investigate class 1-3 integrons and the corresponding resistance gene cassettes in urinary K. pneumoniae isolates.

In this study, from December 2015 to September 2016, a total of 196 K. pneumoniae isolates were collected from the patients with UTI referred to medical diagnostic laboratories in Yasouj, Southwestern Iran. Antibiotic susceptibility patterns of isolates were determined using 12 antibiotics by the disc diffusion method. Polymerase Chain Reaction (PCR) was used for detection of integron genes (intI1, intI2, and intI3). The variable regions of integrons were amplified by PCR and sequenced to identify the corresponding gene cassettes.

Thirty-nine different antibiotic resistance profiles were observed among K. pneumoniae isolates. Only 12.2% of K. pneumoniae isolates were found to harbor the intI1 gene. While 17 (60.7%) out of 28 Multidrug Resistance (MDR) K. pneumoniae isolates carried the intI1 gene, only 4.2% of non-MDR isolates harbored intI1 gene. Totally 7 different gene cassette arrays were found in the intI1 gene of K. pneumoniae isolates. The aadA1 was the most prominent gene cassette. Also, high frequency of dfrA containing gene cassettes was observed.

Continuous monitoring and characterization of integrons and their associated gene cassettes could be helpful in controlling the rising rate of antibiotic resistance.