Integron-Associated Antibiotic Resistance in Salmonella typhi

Salmonella enteric serovar Typhi (S. typhi) and paratyphi (S. paratyphi) bacteria exclusively found in humans, cause typhoid fever, an acute, and possibly deadly systemic infection. Typhoid fever is caused by a species of rod-shaped, Gram-negative Enterobacteriaceae called S. typhi. The present study aimed to examine the intI gene and investigate the possible relation between this gene and multi-drug resistance in S. typhi. A total of 30 blood samples were obtained from patients who were suspicious of typhoid fever using the direct strategy of inoculation. Each specimen was injected into a culture of a selective medium, such as XLD and SS agar, and then incubated at 37°C for 24 h. The genomic DNA was extracted through a boiling process. Tris-EDTA was used to suspend bacterial colonies cultured on MacConkey agar plates. The suspension of bacterial colonies was centrifuged for 5 min at 8000×g and for 20 min at -20°C which lyses the organisms and extracts the DNA from the buffer. The supernatant is then transferred to a fresh Eppendorf tube. Gel electrophoresis was carried out utilizing a UV transilluminator. The intI gene for S. typhi was found using a PCR test. The antibiotic sensitivity testing showed that the S. typhi isolates were classed as multi-resistant. These results were confirmed using the polymerase chain reaction (PCR) technique using intI gene where twenty specimens isolated from typhoid patients were positive for S. typhi.