Current perspectives of enteric fever: a hospital-based study from India

The last two decades have seen a change in the pattern of enteric fever with the emergence of multidrug-resistant strains (MDRS), particularly strains resistant to nalidixic acid.

The aim of the study was to undertake a retrospective analysis of blood culture-confirmed cases of enteric fever diagnosed at Safdarjang Hospital, New Delhi, India from January 2001 to December 2003.

The epidemiological details, clinical features, treatment outcome and antimicrobial resistance patterns were studied.

Of 377 blood culture-positive cases, 80.6% were Salmonella typhi and 19.4% Salmonella paratyphi A; 21.7% were children aged under 5 years and 6.1% were under 2 years. A significant decline in MDRS was observed, from 21.9% in 2001 to 12.4% in 2003 (p=0.04). There was a significant increase in nalidixic acid-resistant Salmonella (NARS) from 56.9% in 2001 to 88.9% in 2003 (p=0.0001). Complete resistance to ciprofloxacin (MIC>4 microg/ml) was detected in only two isolates, both Salmonella paratyphi A. Minimal inhibitory concentrations (MICs) of ciprofloxacin for NARS were increased (0.125-0.5 microg/ml) but were within National Committee for Clinical Laboratory Standards susceptibility ranges. NARS had a significantly longer fever defervescence time (7.7 vs 4.7 days, p<0.001) and hospital stay (12.1 vs 8.2 days, p<0.001), and higher rates of complications (55.5% vs 24.0%, p=0.014) and mortality than nalidixic acid-sensitive Salmonella (NASS). The rate of isolation of MDRS was higher in NARS than NASS (18.8% vs 7.3%, p=0.013).

The high rate of occurrence of enteric fever in children <5 years and also of infections caused by Salmonella paratyphi A in India calls for critical re-assessment of vaccination strategy. Nalidixic acid resistance and rising MICs of fluoroquinolones in Salmonella spp pose a new global threat requiring debate on the optimum treatment of enteric fever.