Molecular detection of Class 1, 2, and 3 integrons in hypervirulent and classic Klebsiella pneumoniae isolates: A cross-sectional study.

BACKGROUND AND AIMS: The "hypervirulent" variant of Klebsiella pneumoniae (hvKp) is an emerging pathogen that cause life-threatening infection. The present study was conducted to identify the prevalence of hvKp and to investigate the presence class 1, 2, and 3 integrons in these isolates.

METHODS: A cross-sectional study was conducted at three teaching hospitals, Ahvaz, South-west of Iran, from January 1, 2019 to December 31, 2020. Samples were collected from inpatients and included only the first samples collected from each patient. K. pneumoniae strains were isolated from different specimens using biochemical test and confirmed by targeting 16S-23S rDNA internal transcribed spacer. HvKp isolates were recovered using string test and were further characterized by detection virulence-associated genes ( rmpA , iucA , and magA ). Antibiotic susceptibility patterns of isolates were determined using the disc diffusion method. Isolates were screened for presence the integron genes ( intI , intII , and intIII ) and repetitive element sequence-based polymerase chain reaction (PCR) performed to determine strain relatedness. SPSS version 22 was used for the data analysis.

RESULTS: Seventy-one (77%) of isolates showed multidrug-resistant (MDR) phenotype. HvKP accounted for 14% (13/92) of cKp isolated from blood (46%) and urinary tract infection (38%), and the great majority of them (61.5%; 8/13) exhibited MDR phenotype. Using the PCR assay, 29 of 92 isolates (31.5%) were found to have positive results for the presence of IntI. Three of the IntI -positive strains were hvKP. Class 2 integron was present in 8/92 cKp isolates. Integron Class 2 was found to coexist with Class 1 integron in 3/8 isolates. All integron-positive isolates ( IntI and/or IntII ) were resistant to at least three different classes of antibiotics and showed MDR phenotype. No Class 3 integrons were detected among the isolates.

CONCLUSION: The results of our study revealed that considering the role of integrons in facilitating the acquisition and dissemination of resistance genes among bacteria, monitoring the emergence of hvKp, emphasizing on the mechanism of antimicrobial resistance, can prevent from the spread of carbapenemase-producing hvKp strains.