Managing of the outbreak of staphylococcal food poisoning in primary school

Abstract

Izhodišče: Oktobra 2010 smo imeli na Gorenjskem v eni izmed osnovnih šol z vrtcem izbruh stafilokokne zastrupitve s hrano. Metode: Izvedli smo retrospektivno kohortno epidemiološko raziskavo in izračunali stopnjo obolevnosti v izbruhu ter relativno tveganje (RT) za vsako živilo. Pri obolelih smo kultivirali blato in izbruhanino. Opravili smo terenski ogled z odvzemom vzorca hrane, brisov delovnih površin na snažnost in brisa rok zaposlenih v kuhinji. V okviru usmerjenega pregleda smo trem zaposlenim v kuhinji odvzeli kužnine za mikrobiološke preiskave. Izolatom bakterije Staphylococcus aureus smo določili enterotoksine s testom aglutinacije SET RPLA (Oxoid). Za primerjavo sorodnosti bakterije S. aureus iz živila in humanih vzorcev smo opravili tipizacijo izolatov s pulzno elektroforezo (PFGE). Rezultati: Obolelo je 73 oseb od 374 izpostavljenih. Stopnja obolevnosti je bila 19,5-odstotna. Najpogostejši bolezenski znaki so bili: bruhanje (87,7 %), bolečine v trebuhu (75,3 %), driska (64,2 %) in slabost (59,3 %). Največje relativno tveganje (RT) za zastrupitev je bilo povezano z uživanjem mesnega sira (RT= 24,2 (95 % CI 12,1-48,5; p<0,001) in krompirjeve solate (RT= 19,4 (95 % CI 10,7-35,2; p<0,001). S kože rok osebe, zaposlene v kuhinji, iz vzorca hrane in kužnin obolelih otrok smo izolirali bakterijo S. aureus, ki je izločala enterotoksina A; po občutljivosti za antibiotike se ni razlikovala od drugih; z metodo PFGE se je pokazala 96,3-odstotna sorodnost med sevi. Zaključki: Opisana raziskava je vzorčen primer dela in ukrepanja področnega epidemiologa in mikrobiologa ob pojavu izbruha. V izbruhu smo dokazali epidemiološko povezane izolate in opredelili pomen posameznih preiskav. Background: In October 2010 an outbreak of staphylococcal food poisoning occurred in an elementary school with a kindergarten in Gorenjska. Methods: Using a questionnaire we performed a retrospective cohortanalytical epidemiological study. We calculated attack rate (AR) and relative risk for each food item. In patients we cultivated stools and vomit. We performed an onsite audit where the food samples, environmental samples, and swabs of the hands of the cooks were taken. We performed medical examination of those employed in the kitchen where specimens were taken for microbiological examination. Staphylococcal enterotoxins were detected with agglutination test SET RPLA (Oxoid) and genotypes determined by the pulsed-field gel electrophoresis (PFGE). Results: Out of 374 exposed 73 subjects got ill. Attack rate in the outbreak was 19,5 %. The most frequent symptoms were vomiting (87,7 %), stomach ache (75,3 %), diarrhea (64,2 %) and nausea ( 59,3 %). The highest relative risk (RR) were found for the meatloaf (RR= 24,2 (95 % CI 12,1-48,5; p<0,001)) and potato salad (RR= 19,4 (95 % CI 10,7 - 35,2; p<0,001)). Enterotoxin A producing S. aureus was isolated from hand of a cook, from potato salad and meatlof, from vomit and stools of patients. These strains had the same antibiotic sensitivity and were genetically closely related (96,3 %). Conclusions: In the article an optimal team approaches of a community epidemiologist and microbiologist in the occasion of outbreak are described. We confirmed epidemiologically related isolates and determined the importance of individual methods.