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On November 15, 2004, a cluster of three cases of SalmonellaThompson infection was registered by the Norwegian reference laboratory. In the following days further cases occurred, prompting a case–control study among the first 13 cases and 26 matched controls. By December 31, 21 cases had been reported, with the first onset on October 24. Consumption of rucola lettuce (Eruca sativa, also known as rocket salad or arugula) (OR 8,8 1,2–∞) and mixed salad (OR 5,0 1,0–∞) was associated with illness. On November 26, Swedish authorities notified the finding of SalmonellaThompson in rucola lettuce through the EU Rapid Alert System for Food and Feed. Later, several countries reported finding this and other Salmonellaserovars and Campylobacterin rucola produced in Italy. In response to our alert through the international Enter-net surveillance network, Sweden and England also reported an increase of cases. SalmonellaThompson isolates from products and patients from several countries showed high similarity by pulsed-field gel electrophoresis, but some isolates showed significant differences. We think that the outbreak in Norway reflected a larger international outbreak caused by rucola imported from one Italian producer. Findings of other pathogens indicate a massive contamination, possibly caused by irrigation with nonpotable water. Rapid international information exchange is invaluable when investigating outbreaks caused by internationally marketed products.

ABSTRACTSeventy-eight human and environmental strains of Salmonella entericasubsp. entericaserovar Typhimurium, as well as 18 isolates of other Salmonellaserovars and 6 isolates of Escherichia coli, were subjected to a novel variable number of tandem repeats (VNTR)-based fingerprinting method that showed high discrimination and reproducibility for typing serovar Typhimurium isolates. The method is based on capillary separation of PCR products from fluorescence-labeled VNTR in the serovar Typhimurium genome. The serovar Typhimurium isolates displayed 54 VNTR patterns, and the VNTR assay correctly identified strains from a well-characterized outbreak. Among 37 serovar Typhimurium phage type DT104 isolates, 28 distinct VNTR patterns were found. This VNTR-based method is fast and suitable for complete automation. Our VNTR-based method was capable of high discrimination within the homogeneous serovar Typhimurium DT104 phage type and can be used to trace outbreaks and to monitor DT104 as well as other phage types. The VNTR assay was compared to XbaI pulsed-field gel electrophoresis, amplified fragment length polymorphism analysis, integron-cassette profiles and gene PCR of intI1, qacE?1, sulI1, and floR. The VNTR assay showed greatly improved resolution compared to all other tested methods in this study.

ABSTRACTAmplified-fragment length polymorphism (AFLP) analysis with the endonucleases BglII and MfeI was used to genotype 91 Campylobacter jejunisubsp. jejunistrains from outbreaks and sporadic cases. AFLP-generated fragments were labeled with fluorescent dye and separated by capillary electrophoresis. The software packages GeneScan and GelCompar II were used to calculate AFLP pattern similarities and to investigate phylogenetic relationships among the genotyped strains. The AFLP method was compared with two additional DNA-based typing methods, pulsed-field gel electrophoresis (PFGE) using SmaI and restriction fragment length polymorphism analysis on PCR products (PCR-RFLP) of theflaAand flaBgenes. We found that AFLP analysis of C. jejunistrains is a rapid method that offers better discriminatory power than do both PFGE and PCR-RFLP. AFLP and, to a lesser extent, PCR-RFLP could differentiate strains within the same PFGE profiles, which also makes PCR-RFLP an alternative to PFGE. We were able to clearly distinguish 9 of 10 recognized outbreaks by AFLP and to identify similarities among outbreak and sporadic strains. Therefore, AFLP is suitable for epidemiological surveillance ofC. jejuniand will be an excellent tool for source identification in outbreak situations.

We have performed amplified‐fragment length polymorphism (AFLP) fingerprinting on a collection of Salmonella entericasubsp. entericaserovar typhimuriumstrains with a restriction endonuclease combination (BglII and MfeI) that has previously been used successfully for typing Campylobacter jejuniisolates with high resolution. Additionally, a variation of the AFLP assay in which two rare cutting restriction enzymes (XbaI and BsrGI) in combination with the frequent cutter (HinP1I) was examined. The BglII and MfeI enzyme combination offered low resolution for genotyping Salmonella typhimuriumisolates and is not recommended for this common serovar. The three‐enzyme combination gave a higher discrimination, and is thus a new alternate way of performing AFLP fingerprinting of S. typhimurium.

ABSTRACTWe have performed the fluorescently labeled amplified-fragment length polymorphism (FAFLP) method on 97 strains of the food-borne pathogen Salmonella entericasubsp. entericacomprising seven different serovars using the restriction enzymesEcoRI and MseI. From the total FAFLP fingerprinted strains, 81 were compared with pulsed-field gel electrophoresis (PFGE) typing of the same strains. The FAFLP method showed a discriminatory power equal to that of PFGE. We report a fast, robust, and high-resolution adaptation of the AFLP assay for fingerprinting S. entericasubsp. entericaserovars with capillary electrophoresis that can be scaled to high throughput on automated analysis instruments.

To assess risk factors and clinical impact of campylobacteriosis in Norway, a case-control study of sporadic cases of infection with thermotolerant Campylobacter spp. was conducted. This report describes: (1) the frequency and duration of signs and symptoms, antimicrobial treatment, hospitalization, and faecal carriage among the study patients; (2) diarrhoeal illness and campylobacter carriage among their household members; and (3) antimicrobial susceptibility pattern among bacterial isolates. A total of 135 patients with bacteriologically confirmed campylobacter infection were enrolled in the study. of these, 58 (43%) were domestically acquired while 77 (57%) were acquired abroad. If the study enrollees are representative of the cases reported to the national surveillance system, the reported infections led to an estimated annual average of at least 8590 days of illness, 78 admissions to hospital, 329 days of hospital stay, 2236 days lost at work or at school, 1000 physician consultations, and 96 antimicrobial prescriptions among the 4.2 million Norwegians. Convalescent carriage of campylobacter was detected in 16% of the patients who submitted follow-up stool specimens; the organism was carried for a mean of 37.6 days (median 31, range 15-69) after the onset of illness. Antimicrobial treatment appeared to have reduced the likelihood of carriage once symptoms had resolved. Diarrhoeal illness was more commonly reported in members of case households than control households (OR = 5.44, p < 0.0001). Cases were more likely than controls to report antecedent recurrent diarrhoea (OR = 6.00, p = 0.034). Two cases of neonatal infection, probably acquired from the mother at the time of delivery, were detected. Resistance against tetracycline, ampicillin, and trimethoprim-sulphamethoxazole was more common among strains acquired in foreign countries than among domestic strains.

Enterotoxin production after cultivation for 7 days in a refrigerator (3–6°C) was indicated for 4 of 20 strains ofYersinia enterocolitica andY. enterocolitica-like bacteria, by use of the infant mouse assay. These four strains were isolated from wild-living small mammals and water. Three of these isolates (Y. kristensenii, serogroups 11 and 28) were enterotoxigenic at 22 and 37°C as well as at refrigeration temperature. The remaining strain (Y. enterocolitica sensu stricto, serogroup 6) produced enterotoxin only at refrigeration temperature and at 22°C. The results indicate thatY. enterocolitica andY. enterocolitica-like bacteria may be capable of causing food intoxication after food storage at refrigeration temperature. A potential clinical significance of theY. enterocolitica enterotoxin in cold-blooded animals such as fish is suggested.

IgG antibody activity toYersinia enterocolitica serogroup O:3 was detected in sera from 56 (7.4%) of 755 Norwegian military recruits, using an enzyme-linked immunosorbent assay. The highest prevalence was found among recruits from Oslo city (12/56, 21.4%). The recruits answered a questionnaire which covered demographic data, specific exposures, and clinical information. The following risk factors were found to be independently associated with IgG activity in logistic regression analysis: receiving drinking water from a private well (odds ratio (OR)=3.40;p=0.004), being a resident of Oslo city (OR=2.99;p=0.006), and living in eastern Norway (OR=2.25;p=0.015). By univariate analysis, living in an urban area was associated with IgG activity, but this factor did not independently affect risk. Present or previous contact with animals, including pigs, and travels abroad were not associated with an increased risk.Yersinia enterocolitica O:3 seropositive recruits were more likely to report previous surgery for suspected appendicitis than seronegative individuals (OR=4.26;p=0.0024). Among recruits with previous appendectomy, mesenteric lymphadenitis as the sole peroperative finding was more common in patients with IgG activity to Y. enterocolitica O:3 (4/7) than in seronegative patients (1/19) (p=0.01). Recurrent diarrhea, steatorrhea or joint complaints were not associated with antibody activity.

ABSTRACTFrom 1992 to 1994 a screening program for detection of specific Toxoplasma gondiiantibodies involving 35,940 pregnant women was conducted in Norway. For women with serological evidence of primary T. gondiiinfection, amniocentesis and antiparasitic treatment were offered. The amniotic fluid was examined for T. gondiiby PCR and mouse inoculation to detect fetal infection. Infants of infected mothers had clinical and serological follow-up for at least 1 year to detect congenital infection. Of the women 10.9% were infected before the onset of pregnancy. Forty-seven women (0.17% among previously noninfected women) showed evidence of primary infection during pregnancy. The highest incidence was detected (i) among foreign women (0.60%), (ii) in the capital city of Oslo (0.46%), and (iii) in the first trimester (0.29%). Congenital infection was detected in 11 infants, giving a transmission rate of 23% overall, 13% in the first trimester, 29% in the second, and 50% in the third. During the 1-year follow-up period only one infant, born to an untreated mother, was found to be clinically affected (unilateral chorioretinitis and loss of vision). At the beginning of pregnancy 0.6% of the previously uninfected women were falsely identified as positive by the Platelia Toxo-IgM test, the percentage increasing to 1.3% at the end of pregnancy. Of the women infected prior to pregnancy 6.8% had persisting specific immunoglobulin M (IgM). A positive specific-IgM result had a low predictive value for identifying primaryT. gondiiinfection.

Pooled faeces samples from 106 poultry flocks in Norway were examined. Campylobacter fetus subsp. jejuni was isolated from 10 of 100 chicken flocks and from 4 of 6 turkey flocks. Eight of the 14 isolates were classified as biotype C. jejuni, which is frequently associated with human campylobacteriosis. Five strains belonged to the biotype C. coli. One strain was resistant to nalidixic acid but differed from the biotype NARTC in its ability to hydrolyse hippurate. The results indicate that C. fetus subsp. jejuni is widespread among Norwegian poultry.

Spraying poultry carcasses with 1 % lactic acid 10 min after inoculation with Campylobacter jejuni, resulted in a significant reduction in the number of the bacteria after 4 h at 4°C. Some of the inoculated cells, however, survived for at least 144 h. Spraying 10 min after inoculation with 2% lactic acid, totally eliminated all inoculated C. jejuniwithin 24 h. On the other hand, spraying 24 h after inoculation, with either 1 % or 2 % lactic acid did not eliminate all the bacteria. Inoculated C. jejunion poultry carcasses not sprayed with lactic acid, survived at 4°C throughout the sampling period (up to 144 h) and showed little tendency to decrease in number even when the carcasses started to deteriorate. Resident Campylobacters on poultry carcasses were significantly reduced by the lactic acid treatment. Frozen and thawed chickens appeared to show a graying of the skins immediately after spraying with lactic acid, slightly stronger with 2 % lactic acid, but the colour reverted to normal after 24 h. We were not able to observe any colour change on the fresh broiler chickens after lactic acid treatment. Our results indicated that lactic acid had a significant bactericidal effect on C. jejunion both naturally and artificially contaminated poultry carcasses. This effect, however, became manifest only several hours after acid treatment.

We have performed amplified-fragment length polymorphism (AFLP) fingerprinting on a collection of Salmonella enterica subsp. enterica serovar typhimurium strains with a restriction endonuclease combination (BglII and MfeI) that has previously been used successfully for typing Campylobacter jejuni isolates with high resolution. Additionally, a variation of the AFLP assay in which two rare cutting restriction enzymes (XbaI and BsrGI) in combination with the frequent cutter (HinP1I) was examined. The BglII and MfeI enzyme combination offered low resolution for genotyping Salmonella typhimurium isolates and is not recommended for this common serovar. The three-enzyme combination gave a higher discrimination, and is thus a new alternate way of performing AFLP fingerprinting of S. typhimurium.

During October 1988 through January 1990, a study of sporadic Yersinia enterocolitica infections was done in the Oslo region to assess the clinical impact and risk factors for this disease. Sixty-seven case-patients (mean age, 23.4 years) and 132 population-based age-and sex-matched controls were enrolled. Among patients who werewellwhen interviewed, illness lasted a mean of 20 days, but 10% of the others remained symptomatic a year later. Bloody diarrhea occurred only in persons <18 years old (P = .002); joint pain wasmore common in adults (P = .001). Prolonged carriage was found in 47% of patients after resolution of symptoms. Patients were less likely to shed the organism after antimicrobial treatment (relative risk, 0.3; P = .003). Case-patients were more likely than controls to have antecedent enteric illness (odds ratio, 8.2; P < .001). Y. enterocolitica infection in Norway is notable for its severityand chronicity. Postsymptomatic shedding, which occurs commonly, may be reduced by antimicrobial treatment.