title: Seasonal variation in bacterial pathogens isolated from stool samples in Karachi, Pakistan.
abstract: OBJECTIVE
  To determine the seasonal variation of the commonly isolated bacterial pathogens in stool samples.
  
  
  METHODS
  A retrospective descriptive study was undertaken of all the stool samples submitted from within Karachi to the Aga Khan University Hospital Laboratory over a period of five years (January 1997- December 2001) in order to determine the commonly isolated bacterial pathogens and to predict their seasonal variation.
  
  
  RESULTS
  A total of 16379 stool samples were included in this review. Bacterial isolates were found in 6670 stool samples (culture detection rate=40.7%). The mean age at the time of culture of each sub-group was < or = 1 year group (6.58 +/- 3.1 months), 1-5 years (2.13 +/- 0.94 years), 5-14 years (8.3 +/- 2.6 yrs) and adults (43.2 +/- 18.5 years). Male: Female ratio was 1.2:1. Vibrio cholera 01 Ogawa (32.8%), Campylobacter jejuni (17.3%), Enteropathogenic Escherichia coli (9.9%), Salmonella paratyphi b (6.6%) and Shigella flexneri (6.2%) were the most common organisms isolated. These organisms show a distinct seasonal variation with summer predilection.
  
  
  CONCLUSIONS
  In contrast to the previous studies from South Asia, which have identified E. coil, followed by Vibrio cholerae as the most common enteric isolates, we found Vibrio cholera 01 Ogawa followed by Campylobacter jejuni as the most common enteric pathogens isolated in an urban setting. It is important to consider seasonal variation when empirically treating diarrheal diseases in our region.
authors.affiliation: The Aga Khan University Hospital, Karachi.
authors.forename: M
authors.initials: M
authors.lastname: Alam
authors.forename: Y N
authors.initials: YN
authors.lastname: Akhtar
authors.forename: S S
authors.initials: SS
authors.lastname: Ali
authors.forename: M
authors.initials: M
authors.lastname: Ahmed
authors.forename: M
authors.initials: M
authors.lastname: Atiq
authors.forename: A
authors.initials: A
authors.lastname: Ansari
authors.forename: F A
authors.initials: FA
authors.lastname: Chaudhry
authors.forename: H
authors.initials: H
authors.lastname: Bashir
authors.forename: M A
authors.initials: MA
authors.lastname: Bangash
authors.forename: A
authors.initials: A
authors.lastname: Awais
authors.forename: A
authors.initials: A
authors.lastname: Safdar
authors.forename: S F
authors.initials: SF
authors.lastname: Hasnain
authors.forename: A
authors.initials: A
authors.lastname: Zafar
mesh_terms: D000293:Adolescent; D000328:Adult; D001419:Bacteria / Q000302:isolation & purification*; D002648:Child; D002675:Child, Preschool; D003967:Diarrhea / Q000382:microbiology; D005243:Feces / Q000382:microbiology*; D005260:Female; D005759:Gastroenteritis / Q000382:microbiology; D006801:Humans; D007223:Infant; D008297:Male; D010154:Pakistan; D012189:Retrospective Studies; D012621:Seasons