• Characterization of Quinolone Resistance in Klebsiella pneumoniae Isolates from Municipal sewage in Ardabil province, Iran
  • Malek Namaki Kheljan,1,* Malihe Hasanzadeh,2 zohreh neyestani,3 zahra hosseinali,4
    1. Department of Microbiology, School of Medicine, Ardabil university of medical sciences, Iran
    2. Department of Biology, Ardabil Branch Islamic Azad University, Ardabil, Iran
    3. Department of Microbiology, School of Medicine, Ardabil university of medical sciences, Iran
    4. Department of Microbiology, School of Medicine, Ardabil university of medical sciences, Iran


  • Introduction: Antibiotic-resistant genes and bacteria enter the environment in several ways. One of the main points of entry for bacteria that are resistant to antibiotics into the environment is municipal sewage. Public health is in danger when released into the environment because treating bacterial infections is adversely affected by the prevalence of antibiotic-resistant microorganisms in the human population. There are now fewer alternatives for treating infections brought on by Klebsiella pneumoniae (K.pneumoniae) due to the recent emergence of resistant forms of this bacterium, particularly those resistant to fluoroquinolone medications. This bacterium can cause pneumonia, septicemia, meningitis, diarrhea, and bacteremia in infants. In this regard, the primary resistance mechanisms to fluoroquinolone antibiotics in gram-negative bacteria include mutations in DNA gyrase and topoisomerase IV and plasmid-mediated antibiotic resistance genes. In this work, K. pneumoniae isolates from municipal sewage in Ardabil province, Iran, were examined for genetic alterations in the gyrA and parC genes and the frequency of plasmid-mediated quinolone resistance (PMQR) genes.
  • Methods: From municipal sewage, 250 K.pneumoniae isolates were obtained. The isolates were initially detected using standard biochemical testing. Then, using PCR and the proper temperature settings, molecular identification of the 16S ribosomal RNA gene was carried out to confirm K.pneumoniae species. Additionally, agar dilution and the disk diffusion method were used to test antibiotic sensitivity. Additionally, DNA sequencing was carried out to look at mutations linked to quinolone resistance as well as PCR was used to determine the presence of the PMQR, gyrA, and parC genes.
  • Results: In the current investigation, 210 (85%) of the isolates of K.pneumoniae lacked ciprofloxacin resistance. 133 isolates of K.pneumoniae with ciprofloxacin resistance and 17 isolates with Asp87Asn mutation in the GyrA gene. 166 isolates were found to have the S80I mutation in the ParC gene. Furthermore, 156 K.pneumoniae isolates carried the qnrS gene, and 143 isolates had the qnrB gene, according to PCR screening for PMQR determinants. Additionally, 182 K.pneumoniae isolates were found to contain the aac(6')-Ib-cr gene. However, none of the isolates had any of the qnrA, qnrC, qnrD, or qepA genes.
  • Conclusion: Our study's findings demonstrated that the FQ resistance rate was high. Concerning findings included the incidence of PMQR genes in K.pneumoniae isolates as well as alterations in DNA gyrase and topoisomerase IV. Additionally, the interaction of these resistance mechanisms is crucial in establishing high-level FQ resistance. Municipal sewage, therefore, has a significant potential for bacterial and gene resistance to spreading to natural ecosystems and can be hazardous to human health.
  • Keywords: Municipal sewage; Quinolone Resistance; Klebsiella pneumoniae