title: The use of sequential studies in a salmonellosis outbreak linked to continental custard cakes.
abstract: We investigated an outbreak of 54 cases of Salmonella Typhimurium phage type 9 (STM9) with a specific antibiotic resistance pattern. We used sequential analytic studies: two retrospective cohort studies, a case-control study, and a modified case-control study. An outbreak of salmonellosis due to Salmonella Typhimurium PT9 SSu (resistant to streptomycin and sulphafurazole) was identified. Fifty-four cases had illness onset from November 1998 to March 1999. Notifications commenced following a restaurant birthday party in December 1998. An initial cohort and case control study found no association with consumption of custard cake. However, case follow-up identified another cohort of people who had attended a birthday party in February at which 8/27 people who consumed a continental custard cake were ill compared to 0/10 who did not (P = 0.07). A revised case control study found illness was strongly associated with consumption of a particular continental custard cake (Mantel-Haenszel matched OR infinity, P = 0.00004). This report highlights the epidemiological value of using sequential study types, and persisting with the investigation of apparently sporadic food-borne outbreaks.
authors.affiliation: Victorian Public Health Training Scheme, Melbourne Health, Australia.
authors.forename: B
authors.initials: B
authors.lastname: Ward
authors.forename: R
authors.initials: R
authors.lastname: Andrews
authors.forename: J
authors.initials: J
authors.lastname: Gregory
authors.forename: D
authors.initials: D
authors.lastname: Lightfoot
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016022:Case-Control Studies; D015331:Cohort Studies; D016358:Contact Tracing; D003967:Diarrhea / Q000382:microbiology; D004196:Disease Outbreaks; D004531:Eggs / Q000382:microbiology; D004812:Epidemiologic Methods; D005516:Food Microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D012147:Restaurants; D012189:Retrospective Studies; D012478:Salmonella Food Poisoning / Q000453:epidemiology* / Q000209:etiology*; D012486:Salmonella typhimurium / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D013307:Streptomycin / Q000494:pharmacology; D013444:Sulfisoxazole / Q000494:pharmacology; D011795:Surveys and Questionnaires; D014739:Victoria / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents; D013444:Sulfisoxazole; D013307:Streptomycin