Eurosurveillance - Volume 11, Issue 2, 01 February 2006

This report describes the first general outbreak of verocytotoxin-producing E. coli (VTEC) in Denmark. Twenty five patients, 18 children and seven adults, with culture-confirmed VTEC O157:H- infection and indistinguishable pulsed-field gel electrophoresis DNA profiles, were identified during a six month period from September 2003 to March 2004. The outbreak strain possessed the virulence genes: eae, vtx1 and vtx2c. All patients but one presented with diarrhoea; none developed haemolytic uraemic syndrome. The outbreak was restricted to Copenhagen and surrounding areas. A case-control study including 11 cases and 55 matched controls revealed an association between VTEC O157:H- infection and shopping in a specific supermarket chain in Copenhagen and surrounding area, matched odds ratio (OR): 8.7 (95% confidence interval (CI): 1.1-71). After exclusion of three assumed secondary cases, only consumption of a particular kind of organic milk from a small dairy was associated with disease OR: 8.7 (95% CI 1.6-48). Environmental and microbiological investigations at the suspected dairy did not confirm the presence of the outbreak strain, but the outbreak stopped once the dairy was closed and thoroughly cleaned.

Fifteen tularaemia cases were identified after a holiday spent at a converted mill in the Vendee region in France, between 9 and 12 August 2004. The mill was visited, and descriptive, retrospective cohort and environmental investigations were conducted. The 39 people who had stayed at the mill between 24 July and 11 August were asked about symptoms, exposure to food and animals, and leisure activities. A case was defined as a person with evidence of fever and a positive serology (seroconversion or significant rise in antibody titre, or a single titre) = 40. Culture for Francisella tularensis and polymerase chain reaction (PCR) diagnosis was carried out for drinking water, firewood, and domestic animals at the mill. Fifteen cases of tularaemia (38%) were confirmed. Twelve of the cases (80%) had the pulmonary form. None of the patients was admitted to hospital. There was a strong association between infection and participation in a dinner at the mill on 4 August (p<10-8). One of the three dogs present in the dining room was serologically positive for F. tularensis. Results of analysis of environmental samples were negative. These investigations confirmed the occurrence of a cluster of 15 tularaemia cases, in patients who were infected on the evening of 4 August, in a mill in Vend¨¦e, an endemic area for tularaemia. The investigations highlight the existence of nonspecific and benign pulmonary forms of the illness in France. The pulmonary form of infection in the human cases and the positive serology of the dog suggest contamination by inhalation of contaminated particles from the dog¡¯s fur disseminated by the dog shaking itself.

In July 2001, the Norwegian Institute of Public Health (Folkehelseinstituttet, FHI) reported a cluster of Salmonella Enteritidis of phage type 14b infections in Norwegian travellers returning from Greece. An increase in the same uncommon phage type was also registered in Sweden and Finland at the same time. Cases of S. Enteritidis PT 14b in patients returning from Greece were reported in these three Nordic countries in 2001 (303 cases), 2002 (164 cases) and 2003 (199 cases). Case-control studies performed in 2001 in Norway and Sweden indicated that consumption of chicken was associated with illness. In 2002 and 2003, continuing case reports indicated that this uncommon phage type had probably become established in the Greek food chain. Tour operators were informed and contacts were made with Greek public health authorities. Because place of infection is not systematically included in most Salmonella notification systems, the S. Enteritidis phage type 14b outbreak reported here may represent only part of a larger outbreak among travellers visiting Greece. Infections are often reported only in the tourists’ home countries and public health authorities in the tourist destinations may not be aware of the problem. Further collaboration between national institutes of public health in Europe is needed to detect outbreaks occurring among tourists.

We report an outbreak of gastroenteritis due to Salmonella Enteritidis PT 21 associated with attending an annual traditional fair in a small Austrian village on 4 May 2005. The outbreak lasted from 4 to 8 May. Descriptive and analytical epidemiological investigations were conducted in order to determine the extent of the outbreak and to identify outbreak risk factors. Of the 115 persons who visited the fair, 85 persons fulfilled the criteria of an outbreak case (attack rate=73.9%). Stool specimens from 52 patients, including two kitchen staff, were tested for salmonella, and 20 specimens were positive for Salmonella Enteritidis PT 21. The cohort study revealed mixed salad (which included potatoes) as the likely cause of the outbreak (RR: 10.4, 95%CI 2.8 – 39.1; P=<0.001). The causative agent of the outbreak was cultured from the stock of eggs used at the fair and from all three drag swabs and one barn dust sample collected from the responsible egg laying flock. Molecular subtyping by pulsed-field gel electrophoresis of genomic DNA after XbaI digestion showed that isolates from eggs, from the flock and from humans were indistinguishable. We hypothesise that cross contamination from eggs to boiled potatoes occurred in the kitchen area, where raw eggs were handled by village residents preparing a traditional Viennese egg dressing. Unrefrigerated storage of peeled potatoes may have favoured bacterial growth. Eggs from small rural flocks of laying hens kept in a traditional ‘natural’ way should not be assumed to be salmonella-free.

The aim of the present study was to evaluate the needs for surveillance of invasive Gram-negative pathogens in Estonia. The antimicrobial susceptibility data of invasive isolates of Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella spp, Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae and enterococci were collected in accordance with EARSS (European Antimicrobial Resistance Surveillance System) protocols. Despite the higher rate of Gram positive pathogens, their resistance to antimicrobials was low in contrast to the elevated resistance established for Gram negative pathogens. The higher resistance to antimicrobials was particularly associated with A. baumannii and P. aeruginosa. Also, the proportion of extended spectrum betalactamase (ESBL)-producing strains was 23% among Klebsiella spp. and 3.6% among E. coli. The inclusion of invasive Gram negative pathogens in antimicrobial resistance surveillance provides useful information concerning local pathogen susceptibility, as well as for the empirical treatment of suspected infections.