We describe an Escherichia coli O157[ratio ]H7 outbreak associated with a fresh water lake at a county park. Campers were surveyed for diarrhoeal illness within 10 days of their visit, and a case-control study of day visitors was conducted. A confirmed case was a symptomatic person with a stool culture positive for E. coli O157[ratio ]H7 and a probable case was a person with bloody diarrhoea. Clinical isolates of E. coli O157 were subtyped by pulsed field gel electrophoresis (PFGE). In the camper survey, 12 (38%) of 32 swimmers had a diarrhoeal illness (relative risk [RR]=12·4; 95% confidence interval [RR]=1·7–89·7). For the case-control study, the 12 cases were more likely than controls to have purposefully ingested lake water (odds ratio [OR]=6·9, 95% CI=0·9–55·8). The PFGE patterns of six clinical isolates were indistinguishable. This report further demonstrates that contaminated fresh-water lakes can be the source of community outbreaks of E. coli O157[ratio ]H7.

Despite rapid urbanization and increasing affluence in Karachi, cases of cholera are frequent. We analysed computerized isolation data from the AKUH Clinical Microbiology Laboratory, Karachi, from 1990–6 to examine microbiological, temporal and demographic trends in Vibrio cholerae infections. During this period 888 strains of V. cholerae (566 V. cholerae serogroup O1, and 204 V. cholerae serogroup O139) were isolated from specimens from 886 patients; 214/464 were adult inpatients, and 250/464 paediatric inpatients, the remaining 422 outpatients. Isolations peaked between June and August. Overlapping epidemics occurred in 1993 and 1994 of serogroup O1 (May to August), and serogroup O139 (August to October). All ages and social and economic strata were affected. Forty-four percent of all isolates were from children under the age of 5 years. The mean age of all patients with serogroup O1 infections was 19·6 years (±0·9) compared with 36·7 (±1·7) for serogroup O139 infections (P<0·0001, t test). More than a quarter (27%) of all serogroup O1 isolates were from babies under 2 years of age. One patient had a serogroup O1 infection followed by a serogroup O139 infection 1 year later. Another patient was infected with serogroup O1 strains 5 years apart. Emergence of resistant strains was observed, but by 1996 serogroup O139 had disappeared. An aquatic organism, cholera nevertheless continues to take its toll in this city of 11 million situated in a desert.

Three members of family A, who had diarrhoea on 20 October, lived on a small arable farm which had 10 cattle. Manure from the animals was used to fertilize the ground for growing potatoes which were then offered for retail sale, unwashed, directly from the farm. The mother from family B bought potatoes, which were covered with manure, from family A in early November and over the subsequent 10 days she became ill with diarrhoea and her daughter and son both became ill with bloody diarrhoea. The mother from family C visited family B while the daughter from the latter family was symptomatic; the mother developed diarrhoea several days later. The mother and two sons from family D visited family B while the son from the latter family was symptomatic; the first son developed bloody diarrhoea 6 days later which progressed to development of haemolytic-uraemic syndrome. Direct culture of faecal samples onto cefixime rhamnose sorbitol MacConkey agar failed to isolate E. coli O157 from any of the symptomatic patients, and direct culture onto cefixime tellurite sorbitol MacConkey agar isolated the organism from only one patient. In contrast, a combination of isolation of E. coli O157 by immunomagnetic separation and detection of E. coli O157-specific secretory IgA, suggested E. coli O157 infection in all eight symptomatic patients, but not in any of the family members who were not ill. Two children who excreted the organism for 60 and 89 days respectively were the only two patients who did not develop a secretory IgA response. E. coli O157 was not isolated from potatoes from the farm and faecal samples from the farm animals were not available for examination. The study illustrates the need to use the most sensitive methods available during the investigation and follow up of cases of E. coli O157 infection.

Thirty-seven out of 48 people on a coach excursion to northern France developed gastrointestinal symptoms within 4 days of the trip. Twenty-six had stool samples positive for Escherichia coli O111, 8 were also positive for Campylobacter species, and 1 was positive for campylobacter alone. Strains of E. coli were positive for the effacing and attaching protein (eaeA) gene, but negative for other E. coli virulence genes, and therefore belonged to the enteropathogenic E. coli (EPEC) group. Twenty-two out of 37 people in a second party which followed the same itinerary 2 weeks later also became ill. One had a stool sample positive for E. coli O111. Analytical epidemiology suggested that the source of infections was a restaurant in northern France at which both parties had eaten.

In a survey examining the causes of travellers' diarrhoea treated in Tokyo between July 1986 and December 1995, Aeromonas species were isolated from 1265 (5·5%) of 23215 travellers returning from developing countries. Aeromonas species were the fourth most frequent enteropathogen isolated, following enterotoxigenic E. coli (8·5%), Salmonella spp. (7·6%) and Plesiomonas shigelloides (5·6%). Aeromonas species were found in 1191 (5·6%) of 21257 patients with diarrhoea and in 74 (3·8%) of 1958 healthy individuals without diarrhoea. Mixed infection was observed in 512 (40·5%) cases. No significant difference in the prevalence of Aeromonas by year, season, age distributions, or sex was observed, but a slight difference was noted depending on the country where the travellers visited. Of the 1265 Aeromonas isolates, 893 strains (70·6%) were A. veronii biovar sobria, 330 (26·1%) were A. hydrophila, and 42 (3·3%) were A. caviae. The clinical symptoms of patients from whom Aeromonas species was isolated as the only potential enteric pathogen were almost similar, which were watery diarrhoea (about 60%), abdominal cramps (43%), fever (around 15%), and nausea or vomiting (13%). Although the severity of illness was milder than that of enterotoxigenic E. coli alone, these data suggest that Aeromonas species are important enteric pathogens in travellers' diarrhoea.

Plasmid profile analysis by agarose gel electrophoresis was performed on 42 drug resistant strains of Shigella boydii serotypes 1–5, 8, 10, 12–14, collected between 1974 and 1985 from endemic cases of shigellosis in Ethiopia, and their Escherichia coli K12 transconjugants. Resistance factors (R factors) were further characterized by incompatibility testing.

Patterns of small plasmids, less than 15 kb, were similar within each of the individual S. boydii serotypes. Plasmids of about 3·3–3·7 kb were found in all strains of serotypes 2 and 4. Plasmids of about 4·3–4·6 kb were found in about 86% of strains. Serotypes 1, 2 and 3 were characterized by plasmids of about 5·6–5·7 kb. The 6·4·6–7 kb plasmid was found consistently in serotypes 1, 2, 3, 5, 8, 12 and 13 which were resistant to SSu or had an SSu resistance component in their phenotypes. Large plasmids (155–186 kb) were found in most S. boydii strains.

Conjugative drug resistance plasmids, most often coding for three or less drugs, were found in about 26% of drug resistant strains. R-factors, coding for AT resistance (in types 2 and 8), and ASSuT resistance (in type 4), were compatible with all reference plasmids tested. Plasmids belonging to incompatibility groups X and N were found in serotypes 5 and 10, respectively.

A total of 89760 human and 22551 non-human isolates of salmonella were serotyped in Canada during the period 1983–92. There were 2180 reported outbreaks associated with 10065 cases during the 10-year period. The most common salmonella serovars isolated from human and non-human sources were S. typhimurium and S. hadar. The third and fourth most common serovars from human sources were S. enteritidis and S. heidelberg, respectively, and from non-human sources they were S. heidelberg and S. infantis. The number of S. typhimurium isolations from human and non-human sources showed a downward trend over the 10-year period. A total of 222 outbreaks of S. typhimurium associated with 1622 cases occurred. The S. hadar isolations from human and non-human sources reached a peak during the years 1987–90 and declined thereafter. The number of human isolates of S. enteritidis increased until 1985 and fluctuated at a level of 8·3–12·8% of all human isolates thereafter. Seventy-three outbreaks of S. enteritidis infection associated with 568 cases occurred. More than 50% of the S. enteritidis infections in humans were caused by phage type (PT) 8. During the review period, infections caused by PT4 were less common and were almost exclusively found in people who had travelled abroad. The annual isolation rates of S. heidelberg from human and non-human sources increased steadily during the period. Bacteriophage typing of serovars from outbreaks showed that contaminated food products of poultry and bovine origin were common sources of human infection. Salmonella typhi was identified as the cause of 43 small outbreaks affecting 116 persons.

Consumers in the United States continue to eat raw or undercooked foods of animal origin despite public health warnings following several well-publicized outbreaks. We investigated an outbreak of Salmonella serotype Typhimurium infection in 158 patients in Wisconsin during the 1994 Christmas holiday period. To determine the vehicle and source of the outbreak, we conducted cohort and case-control studies, and environmental investigations in butcher shop A. Eating raw ground beef purchased from butcher shop A was the only item significantly associated with illness [cohort study: relative risk=5·8, 95% confidence interval (CI)=1·5–21·8; case control study: odds ratio=46·2, 95% CI=3·8–2751]. Inadequate cleaning and sanitization of the meat grinder in butcher shop A likely resulted in sustained contamination of ground beef during an 8-day interval. Consumer education, coupled with hazard reduction efforts at multiple stages in the food processing chain, will continue to play an important role in the control of foodborne illness.

A cluster of four cases of haemolytic uraemic syndrome in children occurred in Northern Bohemia, Czech Republic, between 15 June and 7 July, 1995. All the cases had significantly elevated titres of anti-O157 lipopolysaccharide (LPS) antibodies as detected by the indirect haemagglutination assay. All but one of them had drunk unpasteurized goat's milk from the same farm within the week before the disease. Evidence of E. coli O157 infection was subsequently found in 5 of 15 regular drinkers of the farm's raw goat's milk; four of them were asymptomatic, 1 had mild diarrhoea at the end of June. Verocytotoxin 2-producing E. coli O157[ratio ]H7 strains of phage type 2 and of identical pulsed-field gel electrophoresis patterns were isolated from 1 of 2 farm goats and from 1 of the asymptomatic goat's milk drinkers. The frequency of anti-O157 LPS antibodies found among regular drinkers of the farm's raw goat's milk (33%; 5 of 15) was significantly higher than that found in control population (0%; none of 45) (P=0·0005; Fisher's exact test). Our findings indicate that goats may be a reservoir of E. coli O157[ratio ]H7 and a source of the infection for humans; raw goat's milk may serve as a vehicle of the pathogen transmission.

The antibiotic susceptibility pattern of Vibrio cholerae O139, Bengal, an emerging intestinal pathogen has been determined by the Kirby Bauer technique and the MIC values of some antibiotics against these strains by agar dilution technique. All the strains were susceptible to tetracycline, norfloxacin, ciprofloxacin and a majority was susceptible to gentamicin (95·7%) and nalidixic acid (82·9%). Only 51% were susceptible to cefotaxime and most strains were resistant to furazolidone (95·7%), ampicillin (87·3%) and co-trimoxazole (91·5%). The study shows the importance of judicious use of antibiotics in cholera cases and the need for monitoring the susceptibility status of these strains particularly because of their ability to cause extra-intestinal infections like septicaemia.

The epidemiology of notified cases of campylobacter gastroenteritis in adults in Nottingham Health District was investigated using a case-control study with a postal questionnaire to ascertain data on risk factors. Over a 14-month period 531 cases (a 73% response rate of all laboratory confirmed cases) and 512 controls replied.

Conditional logistic regression analysis was used to determine independent associations with infection. These included foreign travel (odds ratio (OR) 3·4; 95% confidence intervals (CI) 2·0–5·7), diabetes mellitus (OR 4·1, CI 1·1–17), medication with omeprazole (OR 3·5, CI 1·1–12) and H2 and H2 antagonists (OR 3·7, CI 1·3–15), contact with puppies (OR11·3, CI1·2–105), eating chicken (OR 1·4, CI 1·1–1·8) and drinking milk from bottles with tops damaged by a bird (OR 3·3, CI 1·0–11). Preparing main meals (OR 0·9, CI 0·8–1·0) and drinking delivered milk (OR 0·6, CI 0·4–0·9) were associated with a reduced risk of campylobacter infection.

Foreign travel was reported in 25% of cases and another 15% had significant associations with other risk factors. The majority of cases, 60%, remained unexplained, indicating the need for further evolution of sporadic cases.

Klebsiella infection has been considered to be an uncommon cause of meningitis. To determine its incidence and clinical features, we reviewed the microbiologic records of cerebrospinal fluid (CSF) and blood cultures and the medical records of patients with bacterial meningitis admitted between 1981 and 1995. Klebsiella meningitis was diagnosed in 79 patients with 83 episodes. All patients had klebsiella isolated from CSF and/or blood and typical symptoms and signs of acute bacterial meningitis. Of these, 74 were over 16 years of age and 2 of the 5 children were infants. There was an increased prevalence rate of klebsiella meningitis after 1986. Of the 83 episodes, only 9 occurred between 1981 and 1986, accounting for 7·8% of 115 cases with CSF and/or blood culture-proven acute bacterial meningitis, whereas in 1987–95, there were 74 episodes accounting for 17·7% of 419 bacteriologically proven cases. K. pneumoniae accounted for 69 episodes, K. oxytoca, 11 episodes and K. ozaenae, 3 episodes. Male gender, diabetes mellitus and liver cirrhosis were commonly associated with K. pneumoniae meningitis. Neurosurgical procedures were frequently associated with K. oxytoca meningitis. All three patients with K. ozaenae meningitis had a primary disease of the nasopharyngeal pathway. The mortality rate due to K. pneumoniae was 48·5%, K. oxytoca, 10% and K. ozaenae, 0%. In patients with K. pneumoniae meningitis, poor prognostic factors included age over 60 years, diabetes mellitus, bacteremia and severe neurological deficits on the first day of treatment.

Mycobacterium ulcerans, the organism which causes Buruli or Bairnsdale ulcer, has never been isolated in culture from an environmental sample. Most foci of infection are in tropical regions. The authors describe the first 29 cases of M. ulcerans infection from a new focus on an island in temperate southern Australia, 1992–5. Cases were mostly elderly, had predominantly distal limb lesions and were clustered in a small region in the eastern half of the main town on the island. The authors suspected that an irrigation system which lay in the midst of the cluster was a source of infection. Limitation of irrigation was associated with a dramatic reduction in the number of new cases. These findings support the hypothesis that M. ulcerans has an aquatic reservoir and that persons may be infected directly or indirectly by mycobacteria disseminated locally by spray irrigation.

Changes in Helicobacter pylori seroprevalence were studied determining IgG and IgA antibodies of 408 randomly selected adults aged 15–74 years living in Vammala, Finland in 1973 and of 504 similarly selected subjects in 1994. Seroprevalence increased by age at both time points. The age-adjusted seroprevalence rate was clearly lower in 1994 than in 1973 (31 vs. 56%, P=0·001). Paired serum samples of 224 subjects collected in 1973 and 1994 showed that the antibody status remained unaltered in 92%; 4% seroconverted and 4% seroreverted within the 21 years. The decrease in the seroprevalence rate in the population and the persistence of individual antibody status over two decades support a difference in H. pylori infection rates among birth cohorts over time rather than continuous acquisition of new infections with advancing age. Thus the risk of helicobacter infection in Vammala, Finland has been highest in childhood and continuously decreased at least for the last five decades.

During a cholera surveillance programme, Vibrio furnissii was isolated in late January and early February 1994 from stool samples collected from 14 persons of whom six had diarrhoea. The remaining eight persons were healthy family members or neighbours to cholera cases. No common source of infection was found. Strains isolated from stool samples each showed typical biochemical reactions of V. furnissii including gas production. Each isolate, except one, agglutinated O-antisera yielding a total of eight different serotypes. Most isolates were sensitive to 10 antibiotics tested, except to ampicillin and the vibriostatic agent O/129 (10 μg). Eight of 14 (57%) strains carried plasmids in the size range 2·6–88 kb, however, no correlation was found between antibiotic susceptibility patterns and plasmid content. Altogether, seven closely related HindIII ribotypes were observed among the 14 V. furnissii isolates studied. V. furnissii strains isolated from family members and other persons living close together often showed different ribotypes suggesting that the isolation was not associated with neighbourhood. Serotyping, plasmid profiling and ribotyping revealed a high strain diversity within V. furnissii, however, the importance of V. furnissii as an enteric pathogen remains to be elucidated.

Data on prevalence and determinants of Helicobacter pylori infection in well-defined populations are scarce. We investigated the prevalence and determinants of active H. pylori infection in a population of out-patients attending a general practitioner in Southern Germany. Infection status was determined by [13C]urea breath test. In addition, information on potential risk factors and medical history was collected.

Five hundred and one of the 531 eligible patients participated in the study (response rate of 94·4%). In total, 117 of the 501 patients had a positive [13C]urea breath test (23·4%). Prevalence of H. pylori infection increased with age from 10·8% (95% CI 5·7–18·1%) in the age group 15–29 years to 30·8% (95% CI 22·1–40·6%) in the age group 60–79 years and was 20·3%, 30·4% and 28·2% for the age groups 30–39, 40–49 and 50–59 years, respectively. Education and childhood living conditions, especially the number of siblings, were identified as additional independent determinants of infection.

A survey of unopened ice cream, ice cream in use, and ice-cream-scoop water (n=91) was conducted to determine the effect of scoop water hygiene on the microbiological quality of ice cream. An aerobic plate count around 106 c.f.u. ml−1 was the modal value for scoop waters. Unopened ice creams generally had counts around 103–104 c.f.u. ml−1 and this increased by one order of magnitude when in use. Many scoop waters had low coliform counts, but almost half contained >100 c.f.u. ml−1. E. coli was isolated in 18% of ice creams in use, and in 10% of unopened ice creams. S. aureus was not detected in any sample. Statistical analysis showed strong associations between indicator organisms and increased counts in ice cream in use. EC guidelines for indicator organisms in ice cream were exceeded by up to 56% of samples.

We report here a new and critical determinant of the effectiveness of hand hygiene procedures, namely the amount of residual moisture left on the hands after washing and drying. When samples of skin, food and utilities were touched with wet, undried hands, microbial numbers in the order of 68000, 31000 and 1900 respectively translocated to these representative surfaces. Bacterial numbers translocating on touch contact decreased progressively as drying with an air or cloth towel system removed residual moisture from the hands. A 10 s cloth towel–20 s air towel protocol reduced the bacterial numbers translocating to skin, food and utilities on touch contact to 140, 655 and 28 respectively and achieved a 99·8, 94 and 99% reduction in the level of bacterial translocation associated with wet hands. Careful hand drying is a critical factor determining the level of touch-contact-associated bacterial transfer after hand washing and its recognition could make a significant contribution towards improving handcare practices in clinical and public health sectors.

To clarify the relationship between the epidemics of severe invasive group A streptococcal infections (streptococcal Toxic Shock-Like Syndrome; TSLS) and common group A streptococcal infections in Japan, we examined the T serotypes of S. pyogenes strains (group A streptococci) isolated from clinical specimens of the streptococcal infections (17999 cases) in the period 1990–5, including the severe infections (TSLS) (29 cases) in the period 1992–5. Characteristic points of the analyses were: (1) dominant serotypes of the infections in these periods were T12, T4, T1, T28 and TB3264, which were consistently isolated; (2) isolates of T3 rapidly increased through 1990 to 1994 while T6 decreased in the period 1990–3; (3) when Japanese area was divided into three parts, T3 serotype tended to spread out from the north-eastern to the south-western area; (4) strains of T3 and T1 serotypes were dominant in the TSLS. Dominant-serotype strains of streptococcal infections did not always induce severe infections and dominance of T3 serotype in the TSLS seemed to be correlated with the increase of T3 in streptococcal infections. These results may indicate that certain clones of S. pyogenes are involved in the pathogenesis of the TSLS.

Two phenotypes of human influenza A(H1N1) virus are currently circulating in Japan. One (group 1) agglutinates both chicken and goose red blood cells (CRBC and GRBC), the other (group 2) agglutinates GRBC but not CRBC. In the 1995/6 season, group 2 viruses accounted for 70% of the H1N1 viruses isolated in MDCK cells. The 1995/6 viruses were located on two branches of the genetic tree. One branch contained both group 1 and group 2 viruses and the other branch contained only group 2 viruses. Group 2 viruses had aspartic acid at residue 225 in the haemagglutinin (HA) protein, the key amino acid residue for group 2 phenotype. The HA protein of group 1 viruses had a change from aspartic acid to asparagine at residue 225 and the expressed HA protein of these viruses adsorbed CRBC. Serial passage of group 2 viruses in MDCK cells or embryonated chicken eggs caused these viruses to gain the ability to agglutinate CRBC. MDCK-adapted viruses had the same amino acid sequences of HA polypeptide as the original ones, but egg-adapted viruses had changed amino acid sequences. The expressed HA protein from one egg-adapted virus that originally belonged to group 2 adsorbed CRBC.