Molecular Detection of gyrA Gene in Salmonella enterica serovar Typhi Isolated from Typhoid Patients in Baghdad

Background and objective: Typhoid fever is endemic in most countries, causing major public health problems with high morbidity and mortality, the resistance of Salmonella enterica serovar Typhi (S. Typhi) towards antimicrobials is recently increased. The aim was to detect the harboring gyrA gene in Typhi Salmonella enterica serovar.

Materials and methods: Twenty Salmonella enterica serovar Typhi isolates were obtained from the Teaching laboratories of the medical city in Baghdad, the isolates were obtained from blood specimens from typhoid patients. Colonies of Salmonella enterica serovar Typhi appeared on CHROM agar and Xylose Lysine Deoxycholate Agar (XLD) as light mauve to mauve-colored and as red with black center colonies, respectively. Polymerase Chain Reaction (PCR) technique was used to detect the presence of the gyrA gene within the twenty isolates with specific primer.

Results: All twenty isolates show the highest resistance rates to Cefazolin 18 (90%), Ciprofloxacin 16 (80%), and Nalidixic acid 15 (75%), while it shows highest sensitivity rates to Cefepime 18 (90%) and Tobramycin 16 (80%) antibiotics. The MIC values show equal to or more than breakpoint of Nalidixic acid and Ciprofloxacin were 15 (75%) and 16 (80%) isolates, respectively.

Conclusion: PCR results showed the presence of gyrA gene (488 bp) in 14 (70%) of isolates (isolate number 1, 2, 3, 4, 7, 8, 9, 10, 12, 13, 14, 15, 18 and 19). On the other hand, 6(30%) isolates (isolate numbers 5, 6, 9, 11, 16, 17, and 20) don't harbor the gyrA gene.

Keywords: Salmonella enterica serovar; Typhi; cefepime; ciprofloxacin; fluoroquinolones; gyrA gene; nalidixic acid; tobramycin.