To assess the importance of infection by Verotoxin (VT) producing Escherichia coli (VTEC) in children with HUS in Central Europe, stool and/or serum samples obtained from 147 patients from 28 paediatric centres were prospectively examined for the presence of VTEC and the kinetics of faecal VT titres (FVT), and for VT neutralization titres and antibodies against E. coli O 157 lipopolysaccharide, respectively. Ninety-two percent of the patients had classic (enteropathic) HUS (E+ HUS). Evidence of VTEC infection was obtained in 86% of them. VTEC/FVT were identified in 55/118 E+ cases (47%). A prominent feature was the frequent isolation of sorbitol-fermenting, VT2-producing E. coli O 157. H−. VT1 (C600/H19) was neutralized by 9%, and VT2 (C600/933W) by 99% of the initial serum samples from E+ patients, compared to 3% (VT1) and 100% (VT2) from age-related controls. Fourfold titre rises against VT1 and/or VT2 were observed in 13/70 (19%), and significantly elevated O 157 LPS IgM and/or IgA antibodies in 106/128 (83%) of the E+ patients. The ubiquitous VT2 neutralizing principle in the serum of HUS patients as of healthy controls warrants further investigations.

Two cohorts of 10 and 16 calves were followed at weekly or fortnightly intervals from 4–28 and 1–9 weeks respectively to determine whether natural infection by Vero cytotoxin (VT) producing Escherichia coli (VTEC) occurred. Ninety-one of 171 (53%) faecal specimens were VTEC positive and 20–80% of animals at any given time excreted VTEC. Of 104 VTEC strains studied further, 6 different serogroups (O 22.H16; O 25.H5; O 49.H−; O 86.H26; O 88.H25; O 153.H12) and an untypable strain (O ?.H21) were identified. All strains belonging to the same serotype had identical profiles of reactivity with DNA probes to toxins VT1 or 2, LT1 or iI and a probe (CVD419) derived from a plasmid carried by enterohaemorrhagic Escherichia coli O 157.H7. Four of these serotypes were found in the faecal flora of the calves, taken as a group, throughout the 4-month study period. Sixty percent of the strains hybridized with the probe for VT1, 4% with the probe for VT2, and 36% with both probes. Faecal VTEC were significantly associated with overt diarrhoeal illness in animals < 10 weeks of age, but no characteristic profile of markers (serotype or hybridization pattern) in E. coli isolates was associated with diarrhoea. A serological response to VTl was detected in some animals, but faecal VT1 VTEC excretion persisted in spite of seroconversion. VTl seroconversion was not associated with diarrhoea. A serological response to VT2 was not detected even in those animals excreting VT2 VTEC in the faeces.

Plasmids in selected type strains of 26 of the Salmonella enteritidis phage types have been characterized by restriction enzyme fingerprinting and by DNA–DNA hybridization with oligonucleotide probes for Salmonella plasmid virulence (Spv) genes. With one exception, the fingerprints of the 38 MDa plasmids studied were homogeneous but there was heterogeneity in the fingerprints of 59 MDa plasmids found in 4 of the type strains. However all 38 MDa and 59 MDa plasmids were related as was a 45 MDa plasmid identified in the type strain of phage type 19. A 3·5 kb fragment homologous to SpvC was conserved in Hind III digests of all 38 MDa and 59 MDa plasmids, and in the related 45 MDa plasmid. In contrast a 65 MDa plasmid found in the type strain of phage type 10 was not related to these three plasmid molecular weight groups and did not carry the SpvC gene.

An analysis of genotype was made for representative strains of Salmonella dublin. The collection consisted primarily of strains isolated from humans in England and Wales, and were of both intestinal and extra-intestinal origin. Three genetic elements were characterized by DNA hybridization. They were the sprBC genes, extrachromosomal virulence determinants. the salmonella-specific insertion sequence IS200, and the 16S ribosomal RNA genes, a phylogenetic marker. Two clones of S. dublin (SdRI and SdRII) which shared an identical IS200 profile, were identified on the basis of restriction fragment length polymorphism at the 16S rRNA locus. With one exception, all strains harboured a 52 MDa plasmid which contained a conserved 3·7 kbp Hind III fragment homologous to the sprBC mouse-virulence genes of S. typhimurium. However, a single plasmid-free strain of SdRI, isolated from a patient with septicaemia exhibited no spc homology. In SdRI there was no observable genotype distinction between strains causing gastroenteritis or bacteraemia. In contrast, none of the strains of SdRII were from cases of bacteraemia, and all human isolates of this clone were from cases of gastroenteritis.

In recent years, Salmonella enteritidis has become an increasingly important public health problem in Italy. In some parts of the country, the fraction of total human salmonella isolates accounted for by S. enteritidis has risen from 3–4% in the mid-1980s to more than 30% in 1990. Between 1090 and 1991. the number of reported S. enteritidis outbreaks increased more than sixfold. The 33 outbreaks reported in 1991 occurred in seven contiguous regions in northern and central Italy and were clustered in time between June and October: in the majority, products containing raw or undercooked shell eggs were implicated. Five of the egg-related outbreaks that occurred within a 30 kilometre radius over a 7-week period were investigated in detail. A phage type 1 strain containing a 38·9 MDa plasmid appeared responsible for three of the outbreaks, while in the remaining two a phage type 4 strain, also with a 38·9 MDa plasmid was isolated. Efforts are being made to enhance epidemiological surveillance and laboratory evaluation, and the use of pasteurized eggs has been recommended for high-risk populations.

An outbreak of Salmonella typhimurinm definitive type (DT) 193 affecting 206 persons occurred in July and August 1989 in a small town in northern England. A descriptive study suggested that cold meats including pork from a butcher's shop in the town were vehicles of infection. An analytical study of a cohort attending a function in the town showed a significant association between illness and consumption of cold roast pork supplied by the butcher's shop (P = 0·00000004). S. typhimurium DT 193 with the same antibiotic resistance pattern (to ampicillin, streptomycin, sulphonamides and tetracyclines) as the outbreak strain, and possessing a single plasmid of 80 MDa was isolated from samples of meat bought from the shop and implicated in illness, and from samples of pig faeces taken from the farm supplying the shop. It was concluded that inadequate processing of infected pork meat at the shop may have contributed to this outbreak but that cross contamination also played an important part in transmission. Control measures included a temporary closure of the shop and subsequent implementation of a detailed protocol for meat processing and monitoring of all procedures at the shop.

A small cluster of dysenteric illness, due to Shigella flexneri, was identified among technical assistants of a primate research unit. All of the affected individuals had been in regular contact with a colony of cynomolgus macaque monkeys, one of which was known to have suffered from acute haemorrhagic colitis in the preceding few weeks. Four monkeys were found to be excreting S. flexneri bacilli of identical antigen type (lb) to that isolated from the human cases. Investigation of working practices revealed the potential for inadvertent faecooral spread and the need to improve existing control methods. We conclude that this small outbreak of shigellosis represents a primate-associated occupational zoonosis. The risk may not be fully appreciated by handlers or their doctors.

Gentamicin-resistant Escherichia coli isolated at different periods from patients in two hospitals were tested for resistance to the aminoglycoside antibiotic apramycin. Twenty-four of 93 (26%) gentamicin-resistant isolates collected from the Royal Liverpool Hospital between 1981 and 1990 were resistant to apramycin. Thirteen isolates were highly resistant to apramycin (minimal inhibitory concentration (MIC) ≥ 1024 μg/ml). were also resistant to gentamicin, netilmicin and tobramycin, and hybridized with a DNA probe derived from the aminoglycoside acetyltransferase (3)IV (AAC(3)IV) gene. The proportion of gentamicinresistant isolates which had high level resistance to apramycin increased from 7% in 1981–5 to 24% in 1986–90.

Twelve gentamicin-resistant E. coli from Guy's and St Thomas's Hospital isolated between 1977 and 1980 were also tested for resistance to apramycin. For five of these isolates the MICs of apramycin was 32–256 μg/ml. None was shown to have a conjugative plasmid carrying resistance to apramycin and only one hybridized with the DNA probe for the AAC(3)IV enzyme.

A point source outbreak of Campylobacter jejuni affected 11 children in a day nursery. Milk consumed by the children was known to have been pecked by magpies on occasions. Illness was significantly associated with consumption of milk on a single morning. Examination of milk from a bottle pecked after the outbreak yielded campylobacters. The level of contamination was approximately six cells of C. jejuni per 500 ml of milk.

The seasonality of canine births was investigated using records from the Kennel Club and the breeding centre for the Guide Dogs for the Blind Association. In these populations a distinct seasonal pattern was found with a greater number of puppies being born in the summer months than the winter. The hypothesis that the greater number of puppies acquired as pets during the summer months may Contribute to the seasonal rise in human campylobacter cases, seen at this time, is discussed.

A total of 255 samples of droppings collected from a total of 22 different poultry units were examined for the presence of thermophilic campylobaeters and the isolates biotyped using Skirrow's protocol. The organisms were isolated from 90 (35·3%) of all samples. Among the 22 units investigated. 13 (59%) were found to have unsatisfactory management systems, while 7 (32%) and 2 (9%) were found to have unsatisfactory and good systems respectively. Significantly large numbers of isolations, 68 of 147 (46·2%), were made from samples collected from poultry units with poor management (P < 0·005). compared with 19 out of 84 (22·6%) samples which were collected from satisfactory units and 3 out of 24 (12·5%) samples collected from units exercising particularly good management. Nineteen of 72 (26·4%) samples collected from broilers, 32 out of 132 (24·2%) samples collected from layers and 39 out of 51 (70·49%) samples collected from indigenous free range poultry were positive for campylobacters. Among the 90 strains isolated from various units, 64 (70·1%) were Campylobacter jejuni. 25 (27·7%) were C. coli. and only 1 (2·2%) was C. laridis.

Aeromonas strains (total = 60) of clinical, water and food origin were tested for adherence to HEp-2 cells. Environmental strains were selected (except for A. caviae) to include primarily those expressing other virulence-associated properties. Adhesion was markedly species-dependent (A. veronii biotype sobria, 15 of 20 [58%], A. caviae, 4 of 12 [33%] and A. hydrophila, 2 of 8 [11%]). A. veronii biotype sobria were adhesive, irrespective of source (62 and 54% for clinical and environmental strains, respectively). Adherent strains of this species were enterotoxin-positive and most (13 of 15) grew at 43 °C. A. caviae isolated from clinical specimens contained a higher proportion (75%) of adherent strains than environmental strains (13%). Virulent subsets of A. veronii biotype sobria and A. caviae are adherent to HEp-2 cells. The HEp-2 assay is a useful model for investigating mechanisms of adherence and enteropathogenicity of virulent Aeromonas species.

Haemophilus ducreyi, the causal organism of chancroid, has increased in significance recently due to its association with HIV transmission. Most previous typing systems have exploited phenotypie characteristics. Detection of ribosomal RNA cistrons, ribotyping, was successfully developed to examine H. ducreyi, but required the use of 32P.

We have used digoxigenin to define ribotypes from 30 strains of H. ducreyi from diverse geographical locations. This was achieved by agarose gel electrophoresis of restriction enzyme (RE) digested DNA extracts. These extracts were vacublotted onto nylon membrane and probed using digoxigenin labelled complementary DNA probe, prepared from Escherichia coli 16S and 23S ribosomal RNA. From 19 REs tested, Ava II, Hinc II, Bgl II and BstE II gave clear ribotypes. The ribotypes of BstE II and Bgl II used together gave the highest index of discrimination (D = 0·95), 16 types, and showed good reproducibility. This nonradioactive method demonstrates the three important features of a typing system: discrimination, typability and reproducibility.

One hundred and ninety-two strains of Neisseria gonorrhoeae isolated from migrant mine-workers were tested for their susceptibility to antibiotics, auxotyped and serotyped. Of the total, 93 (48%) were acquired locally and 64 (33%) from different geographical locations. Plasmid-mediated resistance to penicillin was found in 28 (14·6%) strains and was associated predominantly with the presence of 5·0 kb penicillinase encoding plasmid (18/28, 64%). Chromosomal resistance to penicillin (MIC ≥ 1 mg/l) was detected in 14 (7·3%) strains. Resistance to tetracycline was chromosomally and not plasmid-mediated. Antibiotic resistance was encountered most commonly among strains acquired in Natal. The overall gonococcal population was sensitive to ceftriaxone, ciprofloxacin. spectinomycin and azithromycin. Nine auxotype/serovar (A/S) classes were encountered among penicillinase-producing N. gonorrhoeae (PPNG) compared to 24 A/S classes among non-PPNG strains. The most common A/S class was NR/IA-6 which accounted for 38% of PPNG and 15% of non-PPNG.

Sampling of sera from 202 Sudanese and 124 Swedish children 1–14 years of age was conducted at the end of the 1980s presenting an opportunity to compare the seroprevalence of anti-Neisseria meningitidis (MC) serogroup A antibodies in an area immediately before outbreak of an epidemic (Sudan 1988) with a low endemic area (Sweden). An ELISA antibody assay was developed for detection of antibodies against capsular polysaccharide of MC serogroup A and Haemophilus influenzae type b (Hib). Serum antibody against MC serogroup A was found significantly more frequently in Sudanese than in Swedish children. This indicates that factors other than herd immunity, as measured by serum antibodies against MC serogroup A polysaccharide, are important for avoidance of an MC serogroup A epidemic. The seroprevalence of Hib antibodies was, in contrast, significantly higher in Swedish than in Sudanese children, especially for 5–9-year-old children. A possible explanation may be the different systems of day-care of children in the two countries.

Sanitation is an important problem in relation to the control of pests in urban environments. This investigation analysed the potential risk related to the presence of cockroaches and their capacity for disseminating bacteria in six different types of buildings: hospital nursing area and out-patient area, swimmingpool pool-side and toilet area, low-income flats and food-handling places. Fifty-six species of bacteria were identified from 157 samples. 14 of these have previously been reported as potentially pathogenic for man and vertebrates. Similarities were found between samples collected in (a) the hospital out-patient area and foodhandling establishments and (b) the hospital nursing area and flats. Pool-sides possessed a poorer bacterial flora. There was a greater bacterial specific diversity in food-handling establishments, flats and swimming-bath toilet area. Enterobacter cloacae, Klebsiella pneumoniae and Klebsiella oxytoca were dominant species in flats and the hospital nursing area. Therefore, cockroaches can play a role in disseminating bacteria, which they can carry passively on their cuticle.

Only a small proportion of animals tested were found to be excreting Fusobacterium necrophorum biovar A, the causative organism of necrobacillosis, in the faeces (3 of 69 wallabies, 1 of 66 deer, 2 of 81 cattle). The two positive cattle belonged to a single group of calves on a farm with a history of necrobacillosis and the litter underfoot also readily yielded biovar A organisms. All attempts to demonstrate biovar A in litter on other farms and in soil from an area populated by wallabies and deer failed. Ruminal contents from young beef cattle proved a fertile source of F. necrophorum biovar A, 15 of 18 animals giving a positive result. It is suggested that disturbance of the gastrointestinal microflora leads to intestinal multiplication and faecal excretion of the organism, which may then give rise to necrobacillosis of the body surface.

Oral pretreatment of mice with either a mixture of kanamycin and erythromycin or metronidazole to modify the gut microflora greatly enhanced the faecal excretion of Fusobacterium necrophorum biovar A given by mouth. This lends support to the suggestion that disturbance of the gastrointestinal microflora in animals such as cattle, which often carry the organism in the rumen, may lead to intestinal multiplication and faecal excretion, thereby providing a source of infection that may lead to necrobacillosis of the body surface.

It has been suggested that individuals might be more readily colonized with bacteria that cause meningitis through enhanced binding of the bacteria to virusinfected epithelial cells. As respiratory syncytial virus (RSV) affects infants and children in the age group also susceptible to bacterial meningitis, we tested the hypothesis that infection of HEp-2 cells by RSV might enhance binding of Neisseria meningitidis or Haemophilus influenzae type b (Hib). Attachment of fluorescein-labelled bacteria to HEp-2 cells was measured by flow cytometry, and RSV-infected cells bound significantly more meningococci (P < 0·001) and Hib (P < 0·01) than uninfected cells. Although the isolates expressed different antigenic characteristics (3 meningococci and 5 Hib), all showed a similar pattern of binding. The results are discussed with reference to the methods used for detection of bacterial binding and to interactions that might explain the increased binding to RSV-infected cells.

The epidemic cycle of Chlamydia pneumoniae infection was examined in two areas in eastern Finland over a period of 15 years, 1972–87. The C. pneumoniae IgG antibody prevalence was determined with 5-year intervals in a random sample of the population aged 25–59 years. The total number of sera studied using immunofluorescence was 2387. In 1972 the antibody prevalence was 57% and it increased to 66% in 1977. Over the next 5 years the prevalence decreased to 44% in 1982, but by 1987 it had again increased to 59%. The temporal variation in prevalence was statistically significant (P < 0·001) and similar for both genders. Throughout the observation period the overall prevalence Mas 7–11% higher in men than in women (P < 0·01). The antibody prevalence increased with age, being the highest among the oldest study subjects of both genders. The periods of high and low prevalence alternated in an epidemic cycle (P < 0·001) of about 10 years