Molecular Detection of Extended-spectrum Beta-Lactamase Genes in Salmonella typhi Isolated from Clinical Specimens

Abstract

The presence of extended spectrum β-lactamase (ESBL) - producing organisms significantly affects the course and outcome of an infection and poses a challenge to infection management worldwide. ESBL producing bacteria may not be detected by routine disc susceptibility, lead to inappropriate use of drug, hence treatment failure. In this study polymerase chain reaction technique was used to detect the plasmid genes which encoded for ESBLs enzymes producing by Salmonella typhi in Khartoum State. This study was carried out in the Research Laboratory of the Sudan University of Science and Technology in period Between Decembers 2009 and May 2010. The targeted strains were obtained from same Laboratory, they were isolated from Khartoum State hospitals, were identified as Salmonella typhi, and were tested for sensitivity to third generation of cephalosporin by E.test, which revealed that resistance was 100% to ceftazidime and the isolates were storged in glycerol media at -20C ̊ in research lab (Hassan, 2009). In this study the 12 targeted strains were reactivated on Nutirent agar,6 straine were obtained from this reactivation and they were tested for purity by colonial morphology, Gram stain and APIE, aftar that DNA was extracted from each pure strain of Salmonella typhi by boiling method. Polymerase chain reaction was adopted with specific primers to detect presence of bla TEM, bla SHV and bla CTX-M genes (Patrson, 2003). The results revealed that all strains showed presence of bla CTX-M gene, where in the blaTEM and bla SHV genes showed Negative result in strain number 2 in Salmonella typhi isolates. It is concluded that the bla CTX-M gene, blaTEM and bla SHV genes are the excistant genes in Salmonella typhi isolates in this study. Further studies with large number of isolates are required to validate this research results.