Salmonellosis is a major public health problem worldwide. although most salmonella infections result in mild self-limiting gastroenteritis, some cases of severe and severe infections such as bacteremia, meningitis and typhoid fever may occur. clinical studies conducted in different countries show that the prevalence of nalidixic acid resistant salmonella, which is often shown to reduce the sensitivity of new fluoroquinolones, is increasing. the aim of studying the mutations of qrdrs in parc and pare genes is the clinical samples of salmonella in zahedan teaching hospitals.
In this study, 63 isolates of salmonella isolated from zahedan hospitals were cultured in selective and differential environments. identification of final identity was carried out using salmonella specific antisera. antibiotic test was performed by disk diffusion method, and the mic for the selected antibiotics was determined by microsphere dilution method. nalidixic acid and ciprofloxacin resistant isolates were selected for molecular analysis and amplified in a specific pcr program and examined for mutations.
Among the five isolates resistant to nalidixic acid, each isolate has at least one mutation in the qrdr region of the genes examined. in the review of the qrdr of the parc gene, changes in the amino acid sequence of threonine 57 and serine 80 amino acid changes in asparagine were observed in some isolates. in spite of spot mutations in the qrdr region of gyrb and pare genes, no amino-change in the isolates was found.
The presence of the mutations in the qrdr region of these genes affects antibiotic action and target enzymes and leads to the emergence of resistant phenotypes. antimicrobial susceptibility monitoring for all antibiotic classes is inevitable in order to prevent the emergence of antibiotic resistance.