title: Six-year susceptibility trends and effect of revised Clinical Laboratory Standards Institute breakpoints on ciprofloxacin susceptibility reporting in typhoidalSalmonellaein a tertiary care paediatric hospital in Northern India.
abstract: The antimicrobial trends over 6 years were studied, and the effect of revised Clinical Laboratory Standards Institute (CLSI) breakpoints (2012) for ciprofloxacin susceptibility reporting in typhoidal Salmonellae was determined. A total of 874 (95.4%) isolates were nalidixic acid-resistant (NAR). Using the CLSI 2011 guidelines (M100-S21), 585 (66.9%) isolates were ciprofloxacin susceptible. The susceptibility reduced to 11 (1.25%) isolates when interpreted using 2012 guidelines (M100-S22). Among the forty nalidixic acid susceptible (NAS) Salmonellae, susceptibility to ciprofloxacin decreased from 37 isolates (M100-S21) to 12 isolates (M100-S22). The 25 cases which appeared resistant with newer guidelines had a minimum inhibitory concentration (MIC) range between 0.125 and 0.5 μg/ml. MIC50 for the third generation cephalosporins varied between 0.125 and 0.5 μg/ml over 6 years whereas MIC90 varied with a broader range of 0.19-1 μg/ml. The gap between NAR and ciprofloxacin-resistant strains identified using 2011 guidelines has been reduced; however, it remains to be seen whether additional NAS, ciprofloxacin-resistant isolates are truly resistant to ciprofloxacin by other mechanisms of resistance.
authors.affiliation: Department of Clinical Microbiology and Infectious Diseases, Chacha Nehru Bal Chikitsalaya, New Delhi, India.
authors.forename: R
authors.initials: R
authors.lastname: Saksena
authors.affiliation: Department of Clinical Microbiology and Infectious Diseases, Chacha Nehru Bal Chikitsalaya, New Delhi, India.
authors.forename: C
authors.initials: C
authors.lastname: Nayyar
authors.affiliation: Department of Clinical Microbiology and Infectious Diseases, Chacha Nehru Bal Chikitsalaya; Department of Microbiology (VM), Maulana Azad Medical College, New Delhi, India.
authors.forename: V
authors.initials: V
authors.lastname: Manchanda
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D006776:Hospitals, Pediatric; D006801:Humans; D007194:India; D008826:Microbial Sensitivity Tests / Q000592:standards*; D009268:Nalidixic Acid / Q000494:pharmacology; D011446:Prospective Studies; D012482:Salmonella paratyphi A / Q000187:drug effects*; D012485:Salmonella typhi / Q000187:drug effects*; D062606:Tertiary Care Centers
chemical_list: D000900:Anti-Bacterial Agents; D009268:Nalidixic Acid; D002939:Ciprofloxacin