title: Antimicrobial susceptibility of Salmonella enterica serovars in a tertiary care hospital in southern India.
abstract: OBJECTIVE
  Salmonella enterica serovars Typhi and Paratyphi are predominantly known to cause enteric fever. Multidrug resistance in S. Tphi and S. Paratyphi has emerged as a cause of concern. This study was done to evaluate status in antimicrobial susceptibility patterns of Salmonella enterica serovar Typhi (S. Typhi) and S. Paratyphi obtained from blood culture in a tertiary care hospital in south India.
  
  
  METHODS
  Blood isolates of Salmonella species over a two year period between May 2009 and June 2011 were studied. A total of 322 isolates of Salmonella species were tested for antimicrobial susceptibility by Kirby-Bauer disc diffusion method. The MIC of ciprofloxacin was obtained by E-test, and azithromycin MIC was confirmed by agar dilution method for a limited number of isolates.
  
  
  RESULTS
  Of the total of 322 isolates studied, 186 (57.8%) were S. Typhi, 134 (41.6%) were S. Paratyphi A, and two were S. Paratyphi B. Of these, 44(13.66%) were resistant to ciprofloxacin (MIC <0.50 μg/ml) and 296 (91.9%) were nalidixic acid resistant. Of these 296 nalidixic acid resistant isolates, 278 (94%) were susceptible to ciprofloxacin by MIC criteria (<0.5 μg/ml). Of the 262 isolates tested for azithromycin sensitivity, only 120 (46%) were susceptible, whereas 81 (31%) were resistant and 55 (21%) showed intermediate susceptibility. Of the isolates, 322 (90%) were susceptible to ampicillin and (95%) were susceptible to co-trimoxazole. However, all the isolates were susceptible to chloramphenicol and ceftriaxone.
  
  
  CONCLUSIONS
  Nalidixic acid resistance screening is not a reliable surrogate indicator of ciprofloxacin resistance. Ciprofloxacin MIC should to be routinely done. Azithromycin resistance appears to be emerging. However, isolates showed a high degree of susceptibility to ampicillin, co-trimoxazole and chloramphenicol. Thus, antibiotics like ampicillin and co-trimoxazole may once again be useful for the management of enteric fever in southern India.
authors.affiliation: Department of Infectious Diseases, Apollo Hospitals, Chennai, India. drashwini.tayade@gmail.com
authors.forename: Ashwini
authors.initials: A
authors.lastname: Choudhary
authors.forename: Ram
authors.initials: R
authors.lastname: Gopalakrishnan
authors.forename: P Senthur
authors.initials: PS
authors.lastname: Nambi
authors.forename: V
authors.initials: V
authors.lastname: Ramasubramanian
authors.forename: K Abdul
authors.initials: KA
authors.lastname: Ghafur
authors.forename: M A
authors.initials: MA
authors.lastname: Thirunarayan
mesh_terms: D000667:Ampicillin / Q000627:therapeutic use*; D002701:Chloramphenicol / Q000627:therapeutic use; D002939:Ciprofloxacin / Q000627:therapeutic use; D052978:Disk Diffusion Antimicrobial Tests; D024881:Drug Resistance, Bacterial / Q000235:genetics; D006801:Humans; D007194:India; D008826:Microbial Sensitivity Tests; D009268:Nalidixic Acid / Q000627:therapeutic use; D012482:Salmonella paratyphi A / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D012485:Salmonella typhi / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D063128:Tertiary Health Care; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000627:therapeutic use; D014435:Typhoid Fever / Q000188:drug therapy / Q000382:microbiology*
chemical_list: D009268:Nalidixic Acid; D002939:Ciprofloxacin; D002701:Chloramphenicol; D000667:Ampicillin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination