Trends of Increasing Antimicrobial Resistance in Community Acquired infections- a case study of Enteric fever and health implications

INTRODUCTION:  Increasing antimicrobial resistance in community acquired infections has  increased the cost of healthcare. Enteric fever is an infection  where antibiotic treatment is the  mainstay of treatment and emergence of in resistance in strains causing infections for first line treatment has increased the morbidity and mortality.  Ciprofloxacin is an ideal antibiotic for treatment of enteric fever  but  with its increased use emergence of resistant strains of Salmonella Typhi and S.Paratyphi A,  the main cause of Enteric fever, has been increasing. 

METHODS:  We studied  264 patients of   Enteric fever  who were culture positive for  S.Typhi  (236 ) and S Paratyphi A (28)   during the years 2000 till 2012 attending a north Indian  hospital. The antimicrobial susceptibility of the isolates were studied for ciprofloxacin and other antityphoidal antibiotics. 

RESULTS:  Using the  CLSI  guidelines available till 2012  only  30  S.Typhi    ( 13%) and  one S. Paratyphi A (3%) were Resistant  to ciprofloxacin leading to initial choice for treatment.  Despite the sensitivity there was failure of clinical response to ciprofloxacin and the patients had to be treatment with Ceftriaxone which is administered intravenously, is expensive and requires hospitalization. The cost of treatment overall had increased in these patients.  Recently  due to increasing reports on resistance, CLSI revised  the  breakpoints in   2012 for Extraintestinal salmonella isolates . With reanalysis  181 /236  ( 76%)  of  S.Typhi  and  27/28 (96%)  of  S.Paratyphi A were  interpreted as resistant.  This could have been responsible for inappropriate initial choice.  

CONCLUSIONS:  Trends of resistance over 20 years period have shown that resistance for ciprofloxacin has increased from the year 1993 to 2000 the maximum  MIC was 0.3 , 2000 to 2005 it increased to 8  and from 2006 onwards it has increased to 32. Sensitivity  to chloramphenicol has returned.