Outbreak of hospital-acquired gastroenteritis and invasive infection caused by Listeria monocytogenes, Finland, 2012.

During one week in July 2012, two patients from the same ward at the municipal hospital in Vaasa, Finland, were diagnosed with septicaemia caused by Listeria monocytogenes. An outbreak investigation revealed eight concomitant cases of febrile gastroenteritis caused by L. monocytogenes on the same ward. Median age of the cases was 82 years and median incubation time for listerial gastroenteritis was 21 h (range 9-107). An additional 10 cases of invasive listeriosis caused by the same outbreak strain were identified across the whole country during the summer of 2012. Environmental investigation at the affected municipal hospital ward revealed ready-sliced meat jelly as the suspected source of the infection. During inspection of the meat jelly production plant, one pooled sample taken from a floor drain and a trolley wheel in the food processing environment was positive for the outbreak strain of L. monocytogenes. After the producer stopped the production of meat jelly, no further cases of listeriosis with the outbreak strain were identified via nationwide surveillance.

High frequency of reactive arthritis in adults after Yersinia pseudotuberculosis O:1 outbreak caused by contaminated grated carrots.

OBJECTIVE: We describe the epidemiological and microbiological process in the clearing of a foodborne outbreak of Yersinia pseudotuberculosis O:1 linked to raw carrots and frequency of the associated reactive extra-gastrointestinal manifestations. METHODS: The patient samples were investigated by routine culture or antibody testing methods. The real-time bacterial PCR was used to detect Y pseudotuberculosis in samples from the grated carrots and in those taken from the carrot storage. Genotype of bacterial isolates was determined by pulsed-field gel electrophoresis. For case identification, we retrospectively looked over the laboratory files of the central hospital focusing on the time period of the outbreak. RESULTS: Altogether 49 case patients were identified. Y pseudotuberculosis was detected by real-time PCR analysis in samples taken from grated carrots and from the carrot distributor. Bacterial isolates originating from the farm environment showed identical serotype (O:1) and genotype (S12) with the patients' isolates. Among 37 adults, reactive arthritis (ReA) was found in 8 (22%) and three adults had probable ReA. Six (67%) out of nine human leucocyte antigen (HLA) typed patients with ReA were HLA-B27 positive. Erythema nodosum was found in 42% of the 12 children, whereas none of them had definite ReA. CONCLUSIONS: In this outbreak, Y pseudotuberculosis was for the first time detected in both patient and food samples. ReA was more common than earlier reported in the outbreaks associated with this pathogen; the reason may be that the previous outbreaks have occurred among children. HLA-B27 frequency was higher than usually reported in single-source outbreaks of ReA.

Investigation of increased listeriosis revealed two fishery production plants with persistent Listeria contamination in Finland in 2010.

In 2010, a marked increase in listeriosis incidence was observed in Finland. Listeria monocytogenes PFGE profile 96 was responsible for one-fifth of the reported cases and a cluster of PFGE profile 62 was also detected. Investigations revealed two fishery production plants with persistent Listeria contamination. It appears likely that the plants were at least partly responsible for the increase of listeriosis. Epidemiological investigation revealed that 57% (31/54) of cases with underlying immunosuppressive condition or medication reported eating gravad or cold-smoked fish. Two public notices were issued by THL and Evira informing which groups were most at risk from the effects of listeriosis and should therefore be cautious in consuming certain products. Systematic sampling of foods and adequate epidemiological investigation methods are required to identify the sources of Listeria infections. Continuous control measures at fishery production plants producing risk products are essential.

Multiple-locus variable-number tandem-repeat analysis in genotyping Yersinia enterocolitica strains from human and porcine origins.

Sporadic and epidemiologically linked Yersinia enterocolitica strains (n = 379) isolated from fecal samples from human patients, tonsil or fecal samples from pigs collected at slaughterhouses, and pork samples collected at meat stores were genotyped using multiple-locus variable-number tandem-repeat analysis (MLVA) with six loci, i.e., V2A, V4, V5, V6, V7, and V9. In total, 312 different MLVA types were found. Similar types were detected (i) in fecal samples collected from human patients over 2 to 3 consecutive years, (ii) in samples from humans and pigs, and (iii) in samples from pigs that originated from the same farms. Among porcine strains, we found farm-specific MLVA profiles. Variations in the numbers of tandem repeats from one to four for variable-number tandem-repeat (VNTR) loci V2A, V5, V6, and V7 were observed within a farm. MLVA was applicable for serotypes O:3, O:5,27, and O:9 and appeared to be a highly discriminating tool for distinguishing sporadic and outbreak-related strains. With long-term use, interpretation of the results became more challenging due to variations in more-discriminating loci, as was observed for strains originating from pig farms. Additionally, we encountered unexpectedly short V2A VNTR fragments and sequenced them. According to the sequencing results, updated guidelines for interpreting V2A VNTR results were prepared.

Reactive arthritis following Salmonella infection: a population-based study.

OBJECTIVES: To study the incidence and clinical picture of Salmonella-associated reactive arthritis (ReA), as well as other reactive musculoskeletal symptoms and the arthritogenicity of various Salmonella enterica ssp. enterica serotypes in the population. METHOD: We sent a questionnaire on enteric and extraintestinal (especially musculoskeletal) symptoms to 999 consecutive subjects with a Salmonella-positive stool culture. Analysis of self-reported musculoskeletal symptoms was supplemented with a clinical examination of subjects with recent symptoms. RESULTS: Of the 999 Salmonella-positive subjects, 496 (50%) returned the questionnaire. Of these, 4.4% (22/496) had ReA and 13.7% (68/496) had other reactive musculoskeletal symptoms [tendinitis, enthesopathy, or bursitis (ReTe)]. Among the ReA patients, all adults, Salmonella Enteritidis was the most common causative serotype. The clinical picture of patients with ReA was mostly monoarticular or oligoarticular. Human leucocyte antigen (HLA)-B27 was positive in 42% of patients with ReA. The Salmonella O antigens of the 496 subjects belonged to eight groups (B, C, D1, E, G, I, L, and O), all with different major O antigenic determinants. All 22 patients with ReA and all 68 patients with ReTe were in O antigen groups B, C, D1, or E. However, the occurrence of musculoskeletal complications showed no statistically significant difference in relation to different O antigen groups (p = 0.69). CONCLUSIONS: ReA occurred in 4.4% of patients after Salmonella infection, with an annual incidence of 1.8/100,000 in Finland. We found no differences in arthritogenicity between different Salmonella serotypes that trigger musculoskeletal complications.

Phenotype MicroArray in the metabolic characterisation of Salmonella serotypes Agona, Enteritidis, Give, Hvittingfoss, Infantis, Newport and Typhimurium.

The Phenotype MicroArray (PM) technology was used to study the metabolic characteristics of 29 Salmonella strains belonging to seven serotypes of S. enterica spp. enterica. Strains of serotypes Typhimurium (six strains among definite phage types DTs 1, 40 and 104) and Agona (two strains) were tested for 949 substrates, Enteritidis (six strains of phage type PT1), Give, Hvittingfoss, Infantis and Newport strains (two of each) were tested for 190 substrates and seven other Agona strains for 95 substrates. The strains represented 18 genotypes in pulsed-field gel electrophoresis (PFGE). Among 949 substrates, 18 were identified that could be used to differentiate between the strains of those seven serotypes or within a single serotype. Unique metabolic differences between the Finnish endemic Typhimurium DT1 and Agona strains were detected, for example, in the metabolism of D-tagatose, D-galactonic acid gamma-lactone and L-proline as a carbon source. Thus, the PM technique is a useful tool for identifying potential differential markers on a metabolic basis that could be used for epidemiological surveillance.

Population-based surveillance study of Campylobacter infections in Finland.

The annual incidence in 14,361 campylobacteriosis cases reported in Finland in 2002-2005 varied between 61 and 76/100,000 population. The mean incidence was highest (148/100,000) in the 25-29 years age group and lowest (range 21-24/100,000) in children aged 5-14 years and patients aged ≥75 years. The number of domestic cases was low in winter and peaked in summer. A total of 622 strains isolated from domestic infections and 785 foreign travel-related strains were serotyped. Serotypes Pen 3 and Pen 37 had the strongest association with travel-related infections (96%, P<0·001), and Pen 6,7, Pen 12 and Pen 27 were significantly associated with domestic infections (>70% domestic within each serotype, P<0·001). Pen 2 and Pen 1,44 were less common in older than in younger patients. Of domestic strains, a higher proportion of Pen 2 strains was isolated in winter (18%) compared to the other serotypes (0-10%).

Cases of Salmonella Urbana in Finland, the Czech Republic and Latvia, January-February 2010.

A cluster of 14 cases of Salmonella Urbana cases in Finland, the Czech Republic and Latvia were identified in January-February, 2010. The majority of cases (11) were male and children under 16 years of age. The investigation is currently ongoing and comparison of pulsed-field gel electrophoresis (PFGE) profiles of the isolates suggests that the cases may have a common source of infection.

Point-of-care testing of group A streptococcal antigen: performance evaluated by external quality assessment.

The purpose of this study was to evaluate the overall performance of rapid antigen detection (RAD) in group A streptococcus (GAS) in Finland by using the results of external quality assurance (EQA) samples. We also compared the performance of laboratory professionals to that of nursing professionals. Around 22,800 EQA results among a total of 383 laboratories and physician's offices were analysed. Vocational data on the personnel who carried out the tests were available for 10,088 EQA samples, 7,428 of which were tested by laboratory technicians and 2,531 by nursing staff. The best overall performance was found with GAS-negative samples: 99% of the reports were correct. In contrast, the overall performance was only 76% when the samples were weakly positive for GAS antigen. The laboratory technicians performed statistically significantly better than the nursing staff, with both strongly positive (correct results 98.9% vs. 95.1%, respectively; p<0.001) and weakly positive (79.3% vs. 65.3%, respectively; p<0.001) samples. With negative samples, no difference in performance between the laboratory and nursing staff was found (99.5% vs. 99.0%, respectively). The professional skills of the person performing the RAD test for GAS have a major impact on the sensitivity of the test. Based on the results of this study, we suggest that EQA-like artificial specimens could be used as a tool to improve and validate the quality of RAD testing in individual testing sites.

Yersinia enterocolitica and Y. enterocolitica-like species in clinical stool specimens of humans: identification and prevalence of bio/serotypes in Finland.

This study investigated the prevalence of Yersinia enterocolitica (YE) bio/serotypes and YE-like species in clinical stool specimens. The special aim was to find the best methods for accurate identification of YE species and, further, pathogenic strains among YE isolates. Of the 41,848 specimens cultured in ten laboratories during a 12-month period, 473 Yersinia strains were isolated from 462 patients. The strains were identified by 21 biochemical tests, serotyping, colony morphology, as well as by 16S rRNA and gyrB gene sequencing. The most prevalent Yersinia findings were YE biotype 1A (64% of the strains) and pathogenic bio/serotype 4/O:3 (16%). The cold-enrichment increased the number of all isolates, and 25% of the bio/serotype 4/O:3 and 2/O:9 strains were only found by cold-enrichment. In routine diagnostic laboratories, 50% of the YE-like species were identified as YE and in 26% the identification differed from that of the reference laboratory. The microscopic colony identification on CIN agar with positive CR-MOX test, combined with several biochemical tests, identified reliably the pathogenic YE bioserotypes and most YE BT 1A strains, but some strains of the YE-like species were so heterogenic that gene sequencing was the only way to identify them.

New 16-plex PCR method for rapid detection of diarrheagenic Escherichia coli directly from stool samples.

A rapid 16-plex polymerase chain reaction (PCR) suitable for routine diagnostics of diarrheagenic Escherichia coli (EHEC, EIEC, EAEC, ETEC, and EPEC) was developed, validated with control strains, and tested with 250 diarrhoeal stool samples. The specificity was 100% when tested with 289 control bacterial strains, and the analytical sensitivity of automated DNA extraction directly from stool samples was made by boiling the bacterial culture (10(4)-10(5) colony forming units/ml). The assay design starting directly from extraction of stool DNA allowed same day analysis without compromising sensitivity and specificity, which makes it superior compared to PCR after culturing the bacteria. The 16-plex PCR method demonstrated high prevalence of diarrheagenic E. coli in stool samples of patients returning from abroad (39.0%) in contrast to the patients with no travel history (8.7%; p < 0.001). The high prevalence of diarrheagenic E. coli suggests that their screening should be part of normal diarrhoea diagnostics, at least in the leading diagnostic laboratories.

Salmonellosis cases caused by a rare Salmonella Enteritidis PT6c associated with travel to Bulgaria, June-July 2008.

In June 2008 an outbreak of gastroenteritis was registered in Sunny Beach resort situated on the Black Sea coast in Bulgaria, affecting 14 employees of a hotel, five of whom tested positive for Salmonella Enteritidis. During June-July 2008 four sporadic S. Enteritidis cases were also reported and two of them were foreign tourists. In the same period S. Enteritidis cases connected with travel to Bulgaria were reported to the European Centre for Disease Prevention and Control (ECDC) from Finland, United Kingdom, Sweden, Germany and Norway. We describe a study performed to find out relatedness between Bulgarian and Finnish S. Enteritidis isolates using phage typing (PT) and pulse-field gel electrophoresis (PFGE). Fifteen S. Enteritidis isolates from Bulgaria and 195 from Finland (including 28 from travellers to Bulgaria) were phage typed. Within Bulgarian isolates four different PTs were found and PT6c with eight strains was predominant. Nineteen out of 28 strains isolated from the Finns visiting Bulgaria belonged also to PT6c. PFGE typing (with one enzyme) of all S. Enteritidis PT6c strains (8 Bulgarian and 19 Finnish isolates) showed indistinguishable PFGE profile. The typing results thus demonstrated a link between Bulgarian and Finnish S. Enteritidis isolates. We conclude that S. Enteritidis PT6c was the cause of salmonella outbreak in Sunny Beach and was exported to Finland, and likely to the United Kingdom, Norway, Sweden and Germany.

Molecular and phenotypic profiling of sorbitol-fermenting Escherichia coli O157:H- human isolates from Finland.

This study investigated the occurrence of virulence-associated genes, including stx1, stx2, stx2c, stx2d, stx2e, eae and its subtypes (alpha, beta, gamma, epsilon), efa1, cdt-V cluster, enterohaemorrhagic Escherichia coli (EHEC)-hlyA, katP, espP, etpD, sfpA and the flagellar fliC gene, in nine sorbitol-fermenting (SF), beta-glucuronidase-positive E. coli O157:H- (non-motile) isolates obtained from humans in Finland between 1997 and 2001. In addition, the production of Shiga toxin (Stx), cytolethal distending toxin (CDT)-V and EHEC haemolysin (EHEC-Hly) was studied, and the phage type (PT) and pulsed-field gel electrophoresis (PFGE) types were determined. All nine isolates carried eae-gamma, efa1, EHEC-hlyA, etpD, sfpA and fliC; eight also harboured the cdt-V gene cluster and five were positive for stx2. None of the isolates harboured stx1, stx2c, stx2d, stx2e, katP or espP. All isolates harbouring the corresponding genes also produced Stx2 and CDT-V in titres ranging from 1:32 to 1:128 and from 1:2 to 1:4, respectively. None of the isolates expressed EHEC-Hly on enterohaemolysin agar. Seven isolates belonged to PT88 and two had a PT88 variant pattern. Seven isolates showed a close genetic relationship, with a PFGE similarity index (SI) of 92-98%. Two isolates, temporally the first and last, obtained 5 years apart, were the most divergent (SI of 71% and 85%, respectively). The study demonstrated that SF E. coli O157:H- isolates from Finland are closely related and show a close relationship with SF E. coli O157 strains isolated in Germany. This finding suggests a clonality of SF E. coli O157:H- isolates from different geographical regions.

Surveillance of listeriosis in Finland during 1995-2004.

We analysed the surveillance data from listeriosis cases notified to the Finnish National Infectious Diseases Register between 1995 and 2004 and describe our recent experience in investigating clusters of listeriosis cases. The number of annual cases varied between 18 and 53 but no trends in incidence were identified (average annual incidence was 7 cases per million inhabitants). Only a few cases affected pregnant women or newborns. Most of the patients were elderly people with non-malignant underlying illnesses; 25% of them died from their infections. By routine sero- and genotyping of the listeria isolates, we detected several clusters; the vehicle for infection was only identified for two outbreaks. At least one quarter of listeriosis cases (78/315) was caused by a certain sero-genotype or closely related genotypes, which have also been found from vacuum-packed cold-smoked or cold-salted fish products. During 2000-2003, Finnish consumers were repeatedly informed about food precautions for risk groups. The information was also given to attending physicians and prenatal clinics.

Surveillance of listeriosis in Finland during 1995-2004.

We analysed the surveillance data from listeriosis cases notified to the Finnish National Infectious Diseases Register between 1995 and 2004 and describe our recent experience in investigating clusters of listeriosis cases. The number of annual cases varied between 18 and 53 but no trends in incidence were identified (average annual incidence was 7 cases per million inhabitants).

Emerging Salmonella Enteritidis anaerogenic phage type 14b: Outbreak in Norwegian, Swedish and Finnish travellers returning from Greece.

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.

Emerging Salmonella Enteritidis anaerogenic phage type 14b: outbreak in Norwegian, Swedish and Finnish travellers returning from Greece.

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.

Hybrids of Shigatoxigenic and Enterotoxigenic Escherichia coli (STEC/ETEC) Among Human and Animal Isolates in Finland.

Diarrhoeagenic Escherichia coli (DEC) cause serious foodborne infections in humans. Total of 450 Shigatoxigenic E. coli (STEC) strains isolated from humans, animals and environment in Finland were examined by multiplex PCR targeting the virulence genes of various DEC pathogroups simultaneously. One per cent (3/291) of the human STEC and 14% (22/159) of the animal and environmental STEC had genes typically present in enterotoxigenic E. coli (ETEC). The strains possessed genes encoding both Shiga toxin 1 and/or 2 (stx1 and/or stx2 ) and ETEC-specific heat-stable (ST) enterotoxin Ia (estIa). The identified stx subtypes were stx1a, stx1c, stx2a, stx2d and stx2g. The three human STEC/ETEC strains were isolated from the patients with haemolytic uraemic syndrome and diarrhoea and from an asymptomatic carrier. The animal STEC/ETEC strains were isolated from cattle and moose. The human and animal STEC/ETEC strains belonged to 11 serotypes, of which O2:H27, O15:H16, O101:H-, O128:H8 and O141:H8 have previously been described to be associated with human disease. Identification of multiple virulence genes offers further information for assessing the virulence potential of STEC and other DEC. The emergence of novel hybrid pathogens should be taken into account in the patient care and epidemiological surveillance.

Bacteriology of histopathologically defined appendicitis in children.

BACKGROUND: Acute appendicitis is the most common surgical emergency in childhood. However, the pathogenesis and detailed microbiology are obscure. OBJECTIVE: To determine in detail the bacterial etiology of appendicitis in children in relation to the histologic tissue pathology. STUDY DESIGN: Tissue samples obtained at surgery from 41 children with suspected acute appendicitis were examined histologically and by culture for aerobic and anaerobic bacteria. The patients were analyzed according to histopathologic and clinical findings. RESULTS: Aerobic and anaerobic species were isolated from 40 of 41 (98%) samples; on average, 14.1 isolates per specimen (10.4 anaerobes and 3.7 aerobes). Specimens from patients with gangrenous appendices yielded significantly higher numbers of anaerobic isolates per specimen than did specimens from patients with healthy appendices (11.7 vs. 7.7; P < 0.01). Bacteria belonging to the Bacteroides fragilis group were the most frequently isolated anaerobic microorganisms (95%). Other organisms frequently isolated in all histology groups were Peptostreptococcus micros (66%), Bilophila wadsworthia (63%), Fusobacterium nucleatum (44%), Eggerthella lenta (44%) and a hitherto undescribed bile-resistant, pigment-producing Gram-negative rod (41%). Of the aerobes Escherichia coli (88%) and Streptococcus anginosus group (former Streptococcus "milleri" group) organisms (61%) were the most frequent findings. CONCLUSIONS: The shift from histologically normal toward gangrenous appendices was clearly associated with markedly elevated anaerobic bacterial counts in terms of species. The unusually high frequencies of B. wadsworthia (75%) and the hitherto undescribed bile-resistant, pigment-producing Gram-negative rod (56%) in gangrenous appendices represent unique and different findings from those reported in adults.