Emergence of Salmonella Paratyphi A and Submergence of Salmonella Typhi and Their Trend Over Four Years

Abstract

Background: Enteric fever is classically caused by Salmonella enterica serotype Typhi. There has been increase in enteric fever cases from different parts of India caused by Salmonella enterica serotype Paratyphi A. Thereby a retrospective study was conducted to determine the rate of isolation and antimicrobial susceptibility pattern of Salmonella Paratyphi A in comparison to Salmonella Typhi. Methods: A retrospective analysis of laboratory records was carried out from January 2011-December 2014. Conventional blood culture method was used. Salmonella were confirmed by serotyping using group and type specific anti-sera. Antibiotic susceptibility was performed for ampicillin, cotrimoxazole, ciprofloxacin, chloramphenicol and ceftriaxone, using Kirby Bauers disk diffusion method. Results: Out of 258 Salmonella isolates, 127 (49.2 %) were Salmonella Typhi and 131 (50.8 %) were Salmonella Paratyphi A. Salmonella Paratyphi A cases increased from 23.4% in 2011-2013 to 91.3% in 2014. Salmonella Typhi were 98.4 % sensitive to ampicillin and ceftriaxone and 99.2% sensitive to chloramphenicol and cotrimoxazole. Only 29.9% were sensitive to ciprofloxacin. Similarly, Salmonella Paratyphi A isolates were 99.2 % sensitive to ampicillin and 100 % sensitive to cotrimoxazole and ceftriaxone and 96.9 % sensitive to chloramphenicol and only 14.5 % sensitive to ciprofloxacin.Conclusion: The present study confers Salmonella Paratyphi A as the rapidly emerging pathogen of enteric fever. The antibiogram of Salmonella Typhi and Salmonella Paratyphi A showed decreased susceptibility to fluoroquinolones and a notable decrease in the multi drug resistant strains of Salmonella isolates with re-emergence of susceptibility to first line antibiotics.