Emergence of extended-spectrum β-lactamase producing Salmonella typhi in Pakistan

Enteric fever caused by Salmonella typhi, is an increasing health problem affecting the major population in tropical and subtropical regions of the world. Development of multi drug resistance in S. typhi strains has further increased the severity of the problem. In Pakistan and neighboring countries, more than 80% S. typhi strains have been reported as multi drug resistant. A total of 4200 isolates collected during four years study period starting from Jan. 2006 to Dec. 2009, were initially screened using the first-line anti typhoid drugs. Out of them 408 were resistant to all the first-line antityphoid drugs. It was confirmed by polymerase chain reaction that all these isolates contained fliC, sul, catP, tem and gyrA genes. Only three of them (0.7%) had shown extended-spectrum beta-lactamases production by double disk synergy test. Infection control surveillance, better hygiene along with controlled use of anti microbials would minimize the impact of extended-spectrum beta-lactamases and their spread in hospital and intensive care unit patients.