Prevalence of Salmonella typhi in among febrile patients in a tertiary care hospital of South West Rajasthan.

Abstract

<i>Salmonella enterica</i>, serotype typhi, remains the predominant <i>Salmonella</i> species causing enteric fever in India. The mode of <i>Salmonella typhi</i> transmission is considered to be predominantly vehicle-borne through contaminated water or food. In India, the incidence of Salmonella typhi occurs between the months of April and June (dry season) followed by July and September (monsoon season). Typhoid fever may be difficult to distinguish clinically from other febrile illnesses and if left untreated, intestinal, neuropsychiatric, and other complications develop in some patients. The aim of this study was to determine the prevalence of <i>S. typhi</i> in bloodstream infections and its antimicrobial susceptibility pattern among patients with febrile illness. Febrile patients admitted in the hospital who were prescribed blood culture tests and whose samples were sent to microbiology laboratory were included in the study. All blood samples (average 5 mL for adults and 2-3 mL for pediatric age group) were immediately inoculated into Bac-T ALERT aerobic blood culture bottles containing sodium polyethanol sulfonate as an anticoagulant (0.025%). If growth was isolated, isolated colony characteristics of growth and Gram stain were assessed. On Gram staining, typical nonlactose fermenting Gram negative bacilli were further subjected to species identification and detection of antimicrobial susceptibility pattern on the VITEK2. In this study period, a total of 511 blood culture (paired) samples were processed, out of which 47 isolates of <i>Salmonella</i> were obtained. Among these isolates, 33 (70.23%) were from males, and 14 (29.77%) were from females. Amongst these, 35 (74.4%) patients were from rural, 8 (17%) were from subrural, and 4 (8.5%) were from urban areas. Out of the total 47 isolates of <i>Salmonella</i>, 42 (89.36%) were <i>Salmonella typhi</i>, 2 (4.25%) were <i>Salmonella paratyphi</i> A and B each, and 1 (2.12%) was <i>Salmonella enterica</i>. Antimicrobial susceptibility pattern of <i>Salmonella</i> isolates revealed that all the isolates of <i>Salmonella</i> species were highly susceptible (95%-100%) to third generation cephalosporins (ceftazidime, ceftriaxone, cefepime, cefoperazone-sulbactam) and other higher antibiotics such as betalactamase inhibitors - piperacillin tazobactam (95%-100%) and Ticarcillin-clavulanic acid (100%). They were also highly susceptible (100%) to carbapenams (imipenem, merpenem, doripenem, and ertapenem) but showed a fairly decreased susceptibility was towards nalidixic acid with 15% for <i>Salmonella typhi</i> and 50% for other <i>Salmonella</i> isolates. Surging drug-resistant <i>Salmonella enterica</i> cases, the level of resistance was not as high as predicted in our study population. Multidrug-resistant (MDR) trends may vary; therefore, drug susceptibility testing side-by-side to empirical therapy is mandatory, especially in developing countries where there is a practice of self-medication.