Effect of gentamicin and doxycycline on expression of relB and relE genes in Klebsiella pneumonia

Klebsiella pneumoniae is responsible for a variety of disease in hospitalized patients. The goal of this study was to determine that K. pneumoniae isolates possessed toxin-antitoxin II genes such as relE and relB. Other than that, if there was a correlation between the expression of these two genes and antibiotic resistance in K. pneumoniae. Fifty-seven urine samples were collected from Baghdads' hospitals; diagnosed and identified by phenotype and biochemical tests and confirmed with VITEK 2 compact system. Only fifteen isolates which were identified as Klebsiella pneumoniae. Antibiotic sensitivity was identified by using twelve antibiotics discs. K. pneumoniae showed 100% resistance to ceftriaxone, amoxicillin, ticarcillin, ticarcillin with clavulanic acid, ceftazidime, tetracycline, while other antibiotics showed less percent of resistant. Minimum inhibitory concentrations (MICs) of antibiotics detected by using macro tube dilution method to identify the antimicrobial activity for K. pneumoniae. The MIC of gentamicin and doxycycline antibiotics was 1024 Mg/ml, 512 Mg/ml, respectively. The relB (115 bp), and relE (136 pb) genes were detected by polymerase chain reaction. Then gene expression of relB and relE was conducted by using (RT-qPCR) technique treated with sub-MIC concentration of (gentamicin and doxycycline) antibiotics. This study found only ten isolates harbored the two genes. The relB gene expression was increased, but at the same time relE gene expression was decreased compared to control infB1 gene expression. This means the bacterial cell tolerance antibiotics sub-MIC concentrations by maintaining the number of bacteria under stress of antibiotics. Finally, these findings suggest the potential of relB to make K. pneumoniae resistant to antibiotics in their infections under antibiotic stress by the toxin-antitoxin II system.