Relationship of pulsed-field profiles with key phage types of Salmonella enterica serotype Enteritidis in Europe: results of an international multi-centre study

Salmonella is one of the most common causes of foodborne infection in Europe with Salmonella enterica serovar Enteritidis (S. Enteritidis) being the most commonly identified serovar. The predominant phage type for S. Enteritidis is phage type (PT) 4, although PT 8 has increased in incidence. Within these phage types, pulsed-field gel electrophoresis (PFGE) provides a method of further subdivision. The international project, Salm-gene, was established in 2001 to develop a database of PFGE profiles within nine European countries and to establish criteria for real-time pattern recognition. It uses DNA fingerprints of salmonellas to investigate outbreaks and to evaluate trends and emerging issues of foodborne infection within Europe. The Salm-gene database contains details of about 11 700 S. Enteritidis isolates, demonstrating more than 65 unique PFGE profiles. The clonal nature of S. Enteritidis is evidenced by the high similarity and distribution of PFGE profiles. Over 56% (6603/11 716) of the submitted isolates of several different phage types were profile SENTXB.0001, although this profile is most closely associated with PT 4. The next most common profiles, SENTXB.0002 and SENTXB.0005, were closely associated with PT 8 and PT 21 respectively. Studies to investigate the relationship of profile types with outbreaks and possible vehicles of infection suggest that the incidence of PFGE profile SENTXB.0002, and thus PT 8, in some countries may be due to importation of foods or food production animals from Eastern Europe, where PT 8 is amongst the most frequently identified phage types. Collation of subtyping data, especially in the commonly recognized phage types, is necessary in order to evaluate trends and emerging issues in salmonella infection.

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).

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.

Distribution of molecular subtypes within Salmonella enterica serotype Enteritidis phage type 4 and S. Typhimurium definitive phage type 104 in nine European countries, 2000-2004: results of an international multi-centre study

This study investigates the distribution of pulsed-field gel electrophoresis (PFGE) profiles within Salmonella enterica serotype Enteritidis phage type (PT) 4 and S. Typhimurium definitive phage type (DT) 104, from cases of human infection in nine European countries from 2000 to 2004. Isolates were subtyped using standardized methods and gel images submitted by each participating country to the coordinating centre (Health Protection Agency Centre for Infections, London, UK), where they were entered into a central database, developed within BioNumerics software, and designated using an agreed nomenclature. S. Enteritidis PT4 (n=3637) was differentiated into 38 different profiles. Simpson's index of diversity (D) of profiles ranged from 0.2 to 0.4. Profile SENTXB.0001 represented at least 80% of all profiles in each country. S. Typhimurium DT104 (n=1202) was differentiated into 28 different profile types. Simpson's D was at least 0.6 in all countries except in Austria and Italy. In both these countries over 74% of S. Typhimurium DT104 profiles were STYMXB.0013. Profile STYMXB.0061, was predominant in Denmark, Spain, Finland and England and Wales where it represented between 36% and 45% of profiles. Profile STYMXB.0001 represented nearly half of all profiles in Scotland and 23% in England and Wales. PFGE is proving useful for further discrimination within S. Enteritidis PT4 and S. Typhimurium DT104. Ascertainment of international outbreaks involving common serotypes and phage types may be increased by the timely pooling of PFGE profiles within a central database readily accessible to all participating countries.

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.

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.

Three cases of cardiac complications associated with Campylobacter jejuni infection and review of the literature

Presented here are three cases of acute cardiac disease (myocarditis, myopericarditis, and acute atrial fibrillation) associated with Campylobacter jejuni infection, followed by a review of the corresponding literature. Since Campylobacter jejuni is the most common cause of human bacterial enteritis in developed countries, these cases emphasize the importance of keeping cardiac complications in mind when treating patients with acute gastroenteritis due to this pathogen.

Shigatoxigenic Escherichia coli (STEC) infections in Finland during 1998-2002: a population-based surveillance study

During 1998-2002, 124 microbiologically confirmed infections caused by shigatoxigenic Escherichia coli (STEC) were reported in Finland. Of these, 25 (20%) were associated with recent foreign travel. Temporal, geographical and type distribution of the domestically acquired infections (n=99) caused by strains of serogroup O157 (n=52) and non-O157 (n=47) were analysed further. The median age of the patients was 6.8 years (range 0.2-73.1 years). Of the index cases within 26 families, 71% were <5 years old. Family-related infections accounted for 49%, sporadic infections 39%, and 11% were associated with three clusters. Only strains of serogroup O157 carrying eae and stx 2 or its variants caused separate clusters. The incidence of STEC infections was at its highest (0.64/100000) in 1998. Since 1999 it has declined considerably (0.17/100000 in 2002). STEC infections occurred in 14 hospital districts, mostly (28%) in the Helsinki region. However, the incidence was highest (10.3) in northwest Finland.

Reactive arthritis attributable to Shigella infection: a clinical and epidemiological nationwide study

OBJECTIVES

To study the incidence and clinical picture of Shigella associated reactive arthritis (ReA) and the arthritogenicity of various Shigella species in the population.

METHODS

A questionnaire on enteric and extraintestinal, especially musculoskeletal, symptoms was sent to 278 consecutive patients with Shigella positive stool culture and to 597 controls. Analysis of self reported musculoskeletal symptoms was supplemented with clinical examination of those subjects with recent symptoms.

RESULTS

Of the patients, 14/211 (7%) had ReA, and a further 4/211 (2%) other reactive musculoskeletal symptoms (tendonitis, enthesopathy, or bursitis). Of the 14 patients with ReA, all adults, 10 had S sonnei, three S flexneri, and one S dysenteriae infection. HLA-B27 was positive in 36% of the patients with ReA. One control subject had ReA. In the patients with Shigella infection, the odds ratio for developing ReA was 16.2 (95% confidence interval 2.1 to 123.9), p = 0.001.

CONCLUSIONS

ReA occurred in 7% of patients after Shigella infection, with an annual incidence of 1.3/1 000 000 in Finland. Besides S flexneri, S sonnei and S dysenteriae can also trigger ReA.

Multiple outbreaks of Yersinia pseudotuberculosis infections in Finland

During 2001, 89 culture-confirmed cases of Yersinia pseudotuberculosis were reported in Finland; 55 (62%) were serotype O:1, and 34 (38%) were serotype O:3. Four major pulsed-field gel electrophoresis profiles were identified. A case-control study of 25 case patients and 71 healthy controls identified eating outside the home as a risk factor for infection.

Diversity of Listeria monocytogenes isolates of human and food origin studied by serotyping, automated ribotyping and pulsed-field gel electrophoresis

Automated ribotyping, pulsed-field gel electrophoresis (PFGE) and serotyping were evaluated for the epidemiological study of isolates of Listeria monocytogenes collected in Finland in 1997-1999 from human blood (n = 116) and the food industry (n = 72). The isolates divided into six serotypes, 23 EcoRI ribotypes, 54 AscI PFGE types, and 57 final subtypes if all results were combined. The discrimination index of ribotyping was lower (0.873) than that of PFGE (0.946). Two final subtypes dominated among human isolates, and identical subtypes were also found among food industry isolates. All PFGE types were serotype-specific, whereas two ribotypes included isolates of two serotypes. Isolates of serotype 3a, involved in an outbreak in Finland in 1999, matched one of these ribotypes, which also included some food industry isolates of serotype 1/2a. Ribotyping with EcoRI would not have been sufficient to define the outbreak in Finland caused by serotype 3a isolates. Although ribotyping is applicable as the first method in outbreak situations, human and food isolates with identical ribotypes should be investigated further by PFGE.

Molecular characterization of Salmonella enterica subsp. enterica serovar Typhimurium DT1 isolates

Salmonella Typhimurium DT1 is endemic to Finland and has caused human outbreaks since the 1960s. Domestic DT1 isolates (n=235) from 1972 to 1999 from human cases, animals and other sources, as well as foreign DT1 isolates from human cases (n=20) were analysed by molecular methods. Pulsed-field gel electrophoresis (PFGE) yielded 38 XbaI profiles. Of these, XbaI profile 10 was seen in 49% (125/255) of the isolates. Twelve IS200 profiles were obtained; the most common IS200 profile D was seen in 64% (33/52) of the isolates. Two clusters were formed by compilation of the XhaI-, BlnI- and SpeI-PFGE and IS200 profiles and possession of the serovar-specific virulence plasmid. The major cluster contained eight IS200 profiles, including IS200 profile D and XhaI profile 10, and had no virulence plasmid, and can be regarded as typical of the endemic Typhimurium DT1 infection.

Confirmation of Escherichia coli and its distinction from Klebsiella species by gas and indole formation at 44 and 44.5 degrees C

AIMS

In the enumeration of coliform bacteria, confirmation of Escherichia coli has been based upon gas and indole production at the elevated incubation temperature. The test for gas production has recently been questioned. The aim of this study was to investigate the impact of gas production test on the reliability of confirmation of E. coli.

METHODS AND RESULTS

The impact of several media on growth, gas and/or indole formation was tested at 44 and 44.5 degrees C using 547 environmental isolates. These were mainly E. coli, Klebsiella pneumoniae, K. oxytoca and Enterobacter cloacae strains. Another set of 250 faecal and environmental klebsiellae were tested for their maximum temperature for growth (Tmax) and for gas formation. Escherichia coli and even K. pneumoniae grew well in all the media, but gas production was more dependent on the medium used. Growth of the mainly gas negative Ent. cloacae and K. oxytoca strains was still more sensitive to the medium and incubation conditions. Tryptophan salt broth was the most productive medium for the indole test, followed by lauryl tryptose mannitole and tryptone mannitol ricinoleate broth (TRM). Tmax of K. oxytoca was clearly lower than Tmax of K. pneumoniae but a rather high fraction of its isolates produced indole at 44.5 degrees C.

CONCLUSIONS

False-positive E. coli confirmation is possible if gas production is not tested for and the confirmation is based on indole test only.

SIGNIFICANCE AND IMPACT OF THE STUDY

Erroneous positive results on routine analysis for E. coli can occur.

Reactive arthritis after an outbreak of Yersinia pseudotuberculosis serotype O:3 infection

OBJECTIVE

To determine the occurrence and clinical characteristics of reactive arthritis (ReA) after an outbreak of Yersinia pseudotuberculosis serotype O:3 infection.

METHODS

From 15 October to 6 November 1998, a widespread outbreak of Y pseudotuberculosis serotype O:3 occurred in Finland. A questionnaire on musculoskeletal symptoms was mailed to 38 patients with infection confirmed by culture. All patients who reported joint symptoms were interviewed by phone and their medical records of outpatient visits or hospital admission because of recent joint symptoms were reviewed.

RESULTS

Thirty three of 38 (87%) patients returned the questionnaire. Reactive musculoskeletal symptoms were reported by 5/33 (15%): four patients (12%) fulfilled the criteria for ReA and one additional patient had reactive enthesopathy. The patients with ReA were adults (age range 40-47 years), whereas the patient with reactive enthesopathy was a 14 year old boy. In all patients with ReA, the arthritis was polyarticular. In addition to peripheral arthritis, other musculoskeletal symptoms included sacroiliitis (one patient), pain in Achilles tendon (one patient), and heel pain (two patients). HLA-B27 was positive in all the three patients tested. In three of four patients with ReA, the duration of acute arthritis was over six months.

CONCLUSION

Y pseudotuberculosis serotype O:3 infection is frequently associated with ReA and the clinical picture is severe.

Phage typing and PFGE pattern analysis as tools for epidemiological surveillance of Salmonella enterica serovar Bovismorbificans infections

Some years ago, an increase in the number of sporadic cases and outbreaks of salmonellosis due to S. enterica serovar Bovismorbificans was observed in several European countries including Finland, Sweden, England/Wales, Austria, and Germany. In order to understand the recent spread of this serovar and to trace the route of infection back to its source, it was considered necessary to subtype S. Bovismorbificans isolates. Using phage typing (newly described here) and molecular fingerprinting (PFGE-pattern, plasmid profiles and ribotype) the isolates of European origin could be subtyped and compared to S. Bovismorbificans isolates that originated in overseas countries such as Australia, Thailand, India, etc. where this serovar was isolated more frequently. Significant clonal diversity was identified but some of the clonal types of S. Bovismorbificans dominated the epidemics and single cases in Europe as well as in overseas countries. The clonal identity among these isolates indicates an international distribution, new sources of infection, and highlights the urgent requirement for standardized laboratory based surveillance networks (e.g. Enter-Net). Moreover, it is suggested that strains of S. Bovismorbificans will continue to be of concern in public health and that phage typing together with PFGE typing can be applied as reliable and rapid tools for their future monitoring.

Use of phenotyping and genotyping to verify transmission of Escherichia coli O157:H7 from dairy farms

A total of 80 human infections by Escherichia coli O157:H7 were documented in Finland in 1997 and 1998. Most were sporadic and their sources undetermined. Five cases not associated with one another, one of which led to secondary transmission within a family, could be traced to five different dairy farms. These five case patients (age range 2-17 years, median age 3 years) were hospitalised with bloody diarrhoea; two of them developed haemolytic uraemic syndrome. All nine human isolates obtained were sorbitol negative, carried the verocytotoxin 2 and eae genes, and produced verocytotoxin and enterohaemolysin. The phage and pulsed-field gel electrophoresis types of the human and bovine isolates from the corresponding farms were indistinguishable. The cattle (20-70 animals per farm) were monitored for up to 2 years after the human cases. The proportion of cattle excreting the type that caused the human infections varied from 3.2 to 66.7% when sampled soon after the human cases, and from 0.0 to 5.3% about a year or so later. On most of the farms, the animals excreted the pathogen intermittently. On one farm, Escherichia coli O157 isolates with other characteristics were also occasionally isolated. Although the infections were traced back to the farms, it could not be established whether the source was unpasteurised milk or direct or indirect contact with cattle. The results of this study emphasise the need for special recommendations for children visiting or living on a farm to prevent these infections.

Campylobacter-triggered reactive arthritis: a population-based study

OBJECTIVE

To study the incidence and clinical picture of Campylobacter-associated reactive arthritis (ReA) and other reactive musculoskeletal symptoms in the population.

METHODS

A questionnaire on enteric and extraintestinal, including specifically musculoskeletal, symptoms was sent to 870 consecutive patients with Campylobacter-positive stool culture and 1440 matched controls. Analysis of self-reported musculoskeletal symptoms with clinical examination was performed.

RESULTS

Forty-five of the patients (7%) had ReA and eight (1%) had reactive tendinitis, enthesopathy or bursitis. No child had ReA. The arthritis was oligo- or polyarticular, and, in most cases, mild. HLA-B27 was positive in 14% of ReA patients. Of the 45 ReA patients, 37 had C. jejuni and 8 had C. coli infection. No controls had ReA.

CONCLUSION

ReA is common following Campylobacter infection, with an annual incidence of 4.3 per 100000. At the population level, acute ReA is mild, more frequent in adults, and not associated with HLA-B27. Besides C. jejuni, C. coli can trigger ReA.

Reactive arthritis following an outbreak of Salmonella typhimurium phage type 193 infection

OBJECTIVES

To determine the occurrence and the clinical picture of reactive arthritis (ReA) following an outbreak of Salmonella typhimurium.

METHODS

An outbreak of S typhimurium phage type DT 193 occurred in several municipalities in Finland in 1999. A questionnaire which had a specific emphasis on musculoskeletal symptoms was mailed to all 78 subjects with a positive stool culture. Based on the answers, all subjects with recent joint complaints were clinically examined or interviewed by telephone.

RESULTS

Sixty three of 78 subjects (81%) returned the questionnaire. Of these 63 subjects, five (8%) fulfilled the criteria for ReA. All the five subjects with ReA were adults with oligo- or polyarthritis. The antigen HLA-B27 was positive in two of the four subjects tested. In two of five subjects with ReA, the duration of acute arthritis was over six months. Subjects who had received antimicrobial drugs developed acute musculoskeletal symptoms significantly (p=0.013) less often than those without such treatment. None of the subjects with ReA had received antimicrobial drugs before the onset of joint symptoms.

CONCLUSIONS

The occurrence of ReA following an outbreak of S typhimurium was at the same level as in outbreaks due to other salmonella serotypes reported previously by us, indicating that the frequency of ReA after various outbreaks is approximately 10%. Early use of antimicrobial drugs may prevent the development of musculoskeletal symptoms.

Recurrent urinary tract infections in infancy: relapses or reinfections?

Seventeen infants with an index episode of pyelonephritis caused by Escherichia coli were monitored for 18 months for recurrent urinary tract infections (UTIs). All the infants had at least 1 recurrent UTI caused by the same pathogen. Twenty-six recurrent UTI episodes were recorded. The 40 E. coli strains available were analyzed by multiplex polymerase chain reaction for 3 alleles (classes I-III) of the papG gene and by pulsed-field gel electrophoresis (PFGE) after genomial digestion by XbaI. Of the 17 index strains, 12 (71%) carried the papG gene; 67% of these strains had class II alleles. In recurrent UTI isolates, the papG-positive E. coli appeared in 16 (70%) of 23 isolates. The proportion of all recurrent isolates available that represented a strain previously encountered (indistinguishable or highly similar in PFGE) in the same infant was 65%. Our results suggest that most recurrent UTIs in infants are endogenous relapses rather than reinfections caused by new organisms.