Trends in antimicrobial susceptibility of Salmonella Typhi from North India (2001-2012).
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Date
2014-04
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Abstract
Purpose: Enteric fever is endemic in India with Salmonella Typhi being the major causative agent. Antibiotic
therapy constitutes the mainstay of management. The present study was undertaken to find the susceptibility
profile of Salmonella enterica var Typhi (S. Typhi) blood isolates in a tertiary care hospital between January 2001
and December 2012. Materials and Methods: A retrospective analysis of laboratory records was carried out.
Conventional blood culture method was used until 2009; from January 2010 onwards BACTEC 9240 system has
been in use. Salmonella were confirmed by serotyping using group and type specific antisera. Antibiotic susceptibility
was performed using the disk diffusion method. In addition 116 isolates were subjected to minimum inhibitory
concentration testing for chloramphenicol, ciprofloxacin, amoxicillin and nalidixic acid (NA) using agar dilution
and for ceftriaxone and azithromycin using E‑strips (Biomerieux). Result: A total of 1016 typhoidal salmonellae
were obtained. The predominant serotype obtained was S. Typhi (852, 83.8%) followed by Salmonella enterica var
Paratyphi A (164, 16.2%). We observed a re‑emergence of susceptibility to first line antibiotics and a notable decline in
multidrug resistant (MDR) strains. We also found all recent isolates resistant to NA and susceptible to third generation
cephalosporins and 84.5% of isolates having decreasing ciprofloxacin susceptibility using revised criteria as per Clinical
and Laboratory Standards Institute 2012 guidelines. Conclusion: There has been re‑emergence of susceptibility to first
line antibiotics and a notable decline in MDR strains of S. Typhi. We have a very high resistance to NA and decreasing
susceptibility to ciprofloxacin. Third generation cephalosporins and azithromycin seem to be effective therapeutic
options. Judicious use of these antibiotics is mandatory to prevent emergence of resistant strains.
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Keywords
Decreased ciprofloxacin susceptibility, minimum inhibitory concentration, revised zone diameters, Salmonella Typhi
Citation
Singhal L, Gupta P K, Kale P, Gautam V, Ray P.Trends in antimicrobial susceptibility of Salmonella Typhi from North India (2001-2012). Indian Journal of Medical Microbiology. 2014 April-June ; 32 (2): 149-152.