A large outbreak of Listeria monocytogenes infection with short incubation period in a tertiary care hospital.
OBJECTIVE
Listeria monocytogenes is a foodborne pathogen with a high mortality rate. We report a large, nosocomial outbreak of Listeria monocytogenes infection.


METHODS
Patients with L. monocytogenes isolated from a sterile site, or from faeces when diarrhoea and fever were present, were included. Clinical data were collected from the patient records. The incubation period was calculated as the time between exposure and start of symptoms.


RESULTS
Seventeen patients (11 women, median age 64 years) were infected of whom 15 patients were at increased risk for listeriosis. Eleven patients received empiric antibiotic treatment, eight of them with cephalosporins. Three patients died with a resulting mortality rate of 18%. The source of the outbreak was a Camembert cheese made from pasteurised milk containing up to 360 million colony forming units per portion. The median incubation period was 3-4 days.


CONCLUSIONS
The incubation period in this outbreak was significantly shorter than previously reported, a fact that may be due to the high number of ingested bacteria. Furthermore, food restrictions in hospitals seem warranted, as do treatment with antibiotics effective against L. monocytogenes in at-risk populations.
Johnsen
Bjørn Odd
BO
Department of Microbiology, Oslo University Hospital, Rikshospitalet, PB 4950 Nydalen, 0424 Oslo, Norway. Bjorn.Odd.Johnsen@oslo-universitetssykehus.no
Lingaas
Egil
E
Torfoss
Dag
D
Strøm
Erik H
EH
Nordøy
Ingvild
I
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002611:Cheese / Q000382:microbiology; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004196:Disease Outbreaks; D005260:Female; D005517:Foodborne Diseases / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality; D006761:Hospitals; D006801:Humans; D055256:Infectious Disease Incubation Period; D008089:Listeria monocytogenes / Q000302:isolation & purification*; D008088:Listeriosis / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S