Detection of tetracycline resistance genes A and B among clinical isolates of Salmonella Typhi from blood samples in Al-Najaf hospitals

Abstract

The presence of Salmonella spp. antibiotic resistance genes has a significant impact on human health, especially Salmonella Typhi which causes a serious illness called typhoid fever. Therefore, the aim of this research was to detect the dissemination of tetracycline resistance genes among tetracycline-resistant S. Typhi from Al-Najaf hospitals. A total of 1743 blood samples, 2ml from infants, 5 ml from children and 10 ml from adults (according to WHO recommendations), were obtained from outpatient of the hospitals with suspected typhoid fever. 105 (6.02%) isolates were obtained as S. Typhi. Antimicrobial susceptibility tests of S. Typhi isolates were performed by disc diffusion tests and the tetracycline-resistant isolates were screened to detect the presence of tet-A, and tet-B genes by two sets of primers. The PCR products were shown by using 1.5% agarose gel in electrophoresis. Low level of resistance was observed against tetracycline 5 (4.76%). Among the 5 tetracycline-resistant Salmonella isolates, only two isolates carried tet-A gene and one of these 2 isolates carried tet-B gene also. Conclusion Resistance to Salmonella strains is arising and the two cases of tetracycline resistance are alarming.