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Protracted outbreak of S. Enteritidis PT 21c in a large Hamburg nursing home.

Frank C, Buchholz U, Maass M, Schröder A, Bracht KH, Domke PG, Rabsch W, Fell G - BMC Public Health (2007)

Bottom Line: Enteritidis isolates from patients and suspected food vehicles were phage typed and compared.Enteritidis was consistently recovered from patients' stools throughout the outbreak.Suggestions are made to nursing homes, aiding in outbreak prevention.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department for Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany. frankc@rki.de

ABSTRACT

Background: During August 2006, a protracted outbreak of Salmonella (S.) Enteritidis infections in a large Hamburg nursing home was investigated.

Methods: A site visit of the home was conducted and food suppliers' premises tested for Salmonella. Among nursing home residents a cohort study was carried out focusing on foods consumed in the three days before the first part of the outbreak. Instead of relying on residents' memory, data from the home's patient food ordering system was used as exposure data. S. Enteritidis isolates from patients and suspected food vehicles were phage typed and compared.

Results: Within a population of 822 nursing home residents, 94 case patients among residents (1 fatality) and 17 among staff members were counted 6 through 29 August. The outbreak peaked 7 through 9 August, two days after a spell of very warm summer weather. S. Enteritidis was consistently recovered from patients' stools throughout the outbreak. Among the food items served during 5 through 7 August, the cohort study pointed to afternoon cake on all three days as potential risk factors for disease. Investigation of the bakery supplying the cake yielded S. Enteritidis from cakes sampled 31 August. Comparison of the isolates by phage typing demonstrated both isolates from patients and the cake to be the exceedingly rare phage type 21c.

Conclusion: Cake (various types served on various days) contaminated with S. Enteritidis were the likely vehicle of the outbreak in the nursing home. While the cakes were probably contaminated with low pathogen dose throughout the outbreak period, high ambient summer temperatures and failure to keep the cake refrigerated led to high pathogen dose in cake on some days and in some of the housing units. This would explain the initial peak of cases, but also the drawn out nature of the outbreak with cases until the end of August. Suggestions are made to nursing homes, aiding in outbreak prevention. Early outbreak detection is crucial, such that counter measures can be swift and drawn-out outbreaks of nosocomial food-borne infections avoided.

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Related in: MedlinePlus

Handwritten sign in the kitchen reminding staff to place layered cream cake in the patient room fridges upon delivery (in German).
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Figure 3: Handwritten sign in the kitchen reminding staff to place layered cream cake in the patient room fridges upon delivery (in German).

Mentions: During high ambient temperatures in early August, cake – especially layered cream cake served on Sunday 6 August – would have been a very competent food vehicle for Salmonella within the nursing units, especially if the cake had been left standing at room temperatures for hours before consumption. The fact that staff were prone to forget depositing the cake into the fridge upon delivery to the room may be indicated by a hand scribbled remainder photographed during the site visit on a unit kitchen white board (figure 3).


Protracted outbreak of S. Enteritidis PT 21c in a large Hamburg nursing home.

Frank C, Buchholz U, Maass M, Schröder A, Bracht KH, Domke PG, Rabsch W, Fell G - BMC Public Health (2007)

Handwritten sign in the kitchen reminding staff to place layered cream cake in the patient room fridges upon delivery (in German).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2194771&req=5

Figure 3: Handwritten sign in the kitchen reminding staff to place layered cream cake in the patient room fridges upon delivery (in German).
Mentions: During high ambient temperatures in early August, cake – especially layered cream cake served on Sunday 6 August – would have been a very competent food vehicle for Salmonella within the nursing units, especially if the cake had been left standing at room temperatures for hours before consumption. The fact that staff were prone to forget depositing the cake into the fridge upon delivery to the room may be indicated by a hand scribbled remainder photographed during the site visit on a unit kitchen white board (figure 3).

Bottom Line: Enteritidis isolates from patients and suspected food vehicles were phage typed and compared.Enteritidis was consistently recovered from patients' stools throughout the outbreak.Suggestions are made to nursing homes, aiding in outbreak prevention.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department for Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany. frankc@rki.de

ABSTRACT

Background: During August 2006, a protracted outbreak of Salmonella (S.) Enteritidis infections in a large Hamburg nursing home was investigated.

Methods: A site visit of the home was conducted and food suppliers' premises tested for Salmonella. Among nursing home residents a cohort study was carried out focusing on foods consumed in the three days before the first part of the outbreak. Instead of relying on residents' memory, data from the home's patient food ordering system was used as exposure data. S. Enteritidis isolates from patients and suspected food vehicles were phage typed and compared.

Results: Within a population of 822 nursing home residents, 94 case patients among residents (1 fatality) and 17 among staff members were counted 6 through 29 August. The outbreak peaked 7 through 9 August, two days after a spell of very warm summer weather. S. Enteritidis was consistently recovered from patients' stools throughout the outbreak. Among the food items served during 5 through 7 August, the cohort study pointed to afternoon cake on all three days as potential risk factors for disease. Investigation of the bakery supplying the cake yielded S. Enteritidis from cakes sampled 31 August. Comparison of the isolates by phage typing demonstrated both isolates from patients and the cake to be the exceedingly rare phage type 21c.

Conclusion: Cake (various types served on various days) contaminated with S. Enteritidis were the likely vehicle of the outbreak in the nursing home. While the cakes were probably contaminated with low pathogen dose throughout the outbreak period, high ambient summer temperatures and failure to keep the cake refrigerated led to high pathogen dose in cake on some days and in some of the housing units. This would explain the initial peak of cases, but also the drawn out nature of the outbreak with cases until the end of August. Suggestions are made to nursing homes, aiding in outbreak prevention. Early outbreak detection is crucial, such that counter measures can be swift and drawn-out outbreaks of nosocomial food-borne infections avoided.

Show MeSH
Related in: MedlinePlus