Evaluation of the current trends in the antimicrobial susceptibility patterns of typhoid salmonellae

Background: typhoid fever,being severe systemic illness is controlled in developed world due to enhanced preventive modalities like sanitation,while it continues to plague the south asian countries. salmonella typhi is the most widespread etiological agent of enteric fever,with a current rise in salmonella paratyphia strains as well. aims: to find outinvitro antimicrobial susceptibility patterns of typhoid salmonellae isolated from blood culture confirmed cases of typhoid fever to build an imminent approach to improvise empiric therapy. methods: atotal of 141 typhoid salmonellae were isolated from 5115 blood cultures received from different departments of pakistan institute of medical sciences from july 2011 to october 2012. all isolates were further processed for identification using api & serological tests. drug susceptibilities were performed as per clsi 2012 criteria by kirby-bauer disc diffusion and mic's of selected isolates. results:s.typhi (71) &s.paratyphia (70) were isolated in almost equal. predominantly males between 11-30 years were affected. patients between 1-20 years had s.typhi as the predominant organism. combined susceptibilities of typhoid salmonellae showed chloramphenicol (70.9%) as the most sensitive antibiotic,followed by amoxicillin (70.2%) and sxt (65%). more than 90% of resistance was seen with quinolones both in s.typhi and s.paratyphi a. third generation cephalosporins (ceftriaxone) and carbapenems revealed 100% sensitivity. multi drug resistant isolates (21.2%) & extreme drug resistant isolates (12.02%) were all s.typhi. 21% of isolates were β-lactamase producers whereas no esbl production was seen. azithromycin susceptibility was also done but could not be interpreted due to non-availability of interpretive guidelines. conclusions: reversion of susceptibility pattern of first line anti-typhoid drugs noted,but still don't qualify as empirical drugs. at presentthird generation cephalosporins and carbapenems are the only empirical treatment options. flouroquinolones is no more recommended for the treatment of typhoid fever. as no interpretive guidelines are available for azithromycin,so it can be evaluated in future on the basis of its clinical efficacy in therapeutic trials and available guidelines.