Escherichia coli O157.H7 was found in 10 of 3570 (0·28%) faecal samples from dairy cattle in 5 of 60 herds (8·3%). Several tentative associations with manure handling and feeding management practices on dairy farms were identified. Faecal/urine slurry samples, bulk milk samples, and milk filters from dairy herds were negative for E. coli 0157.H7. E. coli 0157.H7 was also isolated from 10 of 1412 (0·71 %) faecal samples from pastured beef cattle in 4 of 25 (16%) herds. The prevalence of E. coli 0157. H7 excretion in feedlot beef cattle was 2 of 600 (0·33 %). The identification of cattle management practices associated with colonization of cattle by E. coli 0157.H7 suggests the possibility that human E. coli O157.H7 exposure may be reduced by cattle management procedures.

From March to October 1993. 15 cases of haemolytic-uraemic syndrome (HUS) in children were detected in a large area of northern Italy, where only 8 cases had occurred in the previous 5 years. Analysis of stool and serum specimens obtained from 14 cases showed evidence of Verotoxin-producing Escherichia coli (VTEC) infection in 13. Serum antibodies to the E. coli O157 lipopolysaccharide (LPS) were found in 8 patients and to the O111 LPS in 2. An O86 VTEC was isolated from another patient. Fourteen children needed dialysis, and 1 died. No obvious epidemiologic link was observed among cases, most of whom lived in small townships. A case-control study did not show an association between HUS and food or exposure to cattle, but suggested an association with contact with chicken coops (OR = 6·5. 95% C.I. 1·2–34·9). However, VTEC were not isolated from stool samples obtained from the chicken coops involved. The risk factors for VTEC infection related to living in rural settlements, including the exposure to live poultry, should be considered in outbreak investigations.

Flagellin gene sequence polymorphisms were used to discriminate amongst 77 strains of Campylobacter jejuni from sporadic and outbreak-associated human enteric infections, and from chickens, sheep and calves. The results were assessed in relation to Lior biotyping and serotyping (Penner somatic antigens). Eight DNA PCR-RFLP patterns (genotypes) were identified by analysis of HinfI fragment length polymorphisms in flagellin gene (flaA) polymerase chain reaction (PCR) products. One genotype (F-l) was a feature of 55% of strains. Strains within the genotypes were heterogeneous with respect to somatic antigens with 12 serogroups represented amongst the C. jejuni isolates of flaA type F-l. Serogroups Pen 1. 2 and 23 were the commonest (45%) amongst the 20 different serogroups represented. Several unique clusters of isolates with diverse biotypes were defined, and one cluster (F-7/Pen 23) contained epidemiologically implicated outbreak strains as well as sheep and calf isolates. We conclude that HinfI flaA typing is reproducible and offers high typability, and its combination with serogrouping provides a novel approach to characterizing isolates of C. jejuni with improved discrimination.

The physiological behaviour of clinical Aeromonas spp. isolates was compared following culture in a conventional broth and human pooled ileostomy fluid (PIF). Protein expression was markedly affected by the growth medium, with an overall reduction in whole cell proteins in bacteria grown in ileostomy fluid. In addition, novel outer membrane proteins were produced in PIF but not in broth. The majority of A. hydrophila and A. sobria isolates produced toxin in both broth and PIF. whereas no cytotoxin positive A. caviae were found. Toxin titres were at least two doubling dilutions higher in 40% and 21% of A. hydrophila and A. sobria isolates, respectively, following culture in brain heart infusion broth compared with PIF. Bacterial adherence to Vero and A-549 cells was significantly more common in A. hydrophila (53%) and A. sobria (64%) than in A. caviae (15%) (P < 0·01). We observed increased adherence by 6 Aeromonas strains previously classified as adherence-positive, but not by 6 non-adherers, in PIF compared with brain heart infusion broth. The influence of growth medium on the expression of potential virulence determinants by Aeromonas spp. provides a rationale for the use of human ileostomy fluid in future in vitro studies, in order to simulate the nutrient conditions found in vivo.

A high incidence of resistance to trimethoprim has been shown in the normal faecal flora in a population in south India. The dihydrofolate reductase (dhfr) genes mediating transferable resistance to trimethoprim have been identified. Unusually, in this study, the dhfr V was shown to be the predominant resistance gene (dhfr V 50% of tranaconjugants, dhfr Ia 30%), the dhfr Ib was also detected being distinguished from the dhfr V by an oligo-probe. However, when non-transferable resistance was considered, the dhfr Ia was the most prevalent of the dhfrs identified. All those plasmids harbouring the dhfr Ia were shown to possess Tn7. All the plasmids that probed positive for the dhfr V and the dhfr Ib were shown to be associated with the integrase of the Tn21-like transposons, but 8 of the dhfr V genes were not associated with the Tn21 resolvase. The dhfr IV was shown to be present in all seven plasmids that produced low level trimethoprim-resistance. The dhfr V. first characterized in Sri Lanka, would seem to have a local distribution in this region of Asia but is distinguishable from the dhfr Ib only by the use of an oligo-probe.

MecA, a structural gene located on the chromosome of Staphylococcus aureus, characterizes methicillin-resistant S. aureus (MRSA), and femA and femB(fem) genes encode proteins which influence the level of methicillin resistance of S. aureus. In order to examine effectiveness of detecting mecA and fem genes in identification of MRSA, the presence of these genes in 237 clinically isolated strains of staphylococci was investigated by polymerase chain reaction (PCR). An amplified mecA DNA fragment of 533 base pairs (bp) was detected in 100% of oxacillin-resistant S. aureus, in 16·7 % of oxacillin-sensitive S. aureus, in 81·5% of S. epidermidis, and in 58·3% of other coagulase-negative staphylococci (CNS). While the PCR product of femA (509 bp) or femB (651 bp) was obtained from almost all the S. aureus strains except for five oxacillin-resistant strains (2·5%), neither of these genes were detected in CNS. Therefore, the detection of femA and femB together with mecA by PCR was considered to be a more reliable indicator to identify MRSA by differentiating it from mecA-positive CNS than single detection of mecA.

To know the types of meningococcal strains in Spain, we serotyped and subtyped 743 Neisseria meningitidis isolates recovered between 1990 and 1992 from patients. A great number of serogroup B, serogroup C and non-groupable meningoccoci reacted with the serotyping reagents while many serogroup C and non-groupable isolates did not react with the serosubtyping reagents (78·2% and 54·8 % respectively); only 8·9 % of serogroup B meningococci were non-subtypeable (NST). Distribution of serotypes was similar in serogroup C and in non-groupable strains. Isolates showed great variability in antigenic phenotypes (71 in serogroup B, 20 in serogroup C and 25 in non-groupable meningococci). The most frequent antigenic combinations were 4:P1. 15 (39·8%) in serogroup B, 2b:NST (55·8%) in serogroup C and 2b:NST (35·6%) in non-groupable meningococci.

Terminal complement component deficiency predisposes to meningococcal infection and is inherited in an autosomal co-dominant manner. An Irish family is described, in which 2 of 3 brothers had recurrent meningococcal infection. A novel screening assay was used to investigate for terminal complement deficiency and the 2 affected brothers were found to be completely deficient in the seventh component of complement (C7). Enzyme-linked immunosorbent assay for C7 revealed lower than normal levels in the remaining brother and parents. C7 M/N protein polymorphism allotyping, used to investigate the segregation of the C7 deficiency genes, showed that the apparently complement sufficient brother was heterozygous C7 deficient and a carrier of one of the deficiency genes. Complement screening should be carried out in any individual suffering recurrent meningococcal infection or infection with an uncommon meningococcal serogroup. Identification of complement deficient patients allows the implementation of strategies to prevent recurrent infection.

A cohort of 4515 surgical patients in ten selected intervention groups was followed. Three hundred and seventeen developed postoperative wound infections, and 291 of these cases were matched 1:1 to controls by operation, sex and age. In comparison to the controls the cases stayed longer in hospital after the intervention and had more contact after discharge with the social security system.

Using data from a national sentinel reference database of the incidence of postoperative wound infections, and using national activity data, we established an empirical cost model based on the estimated marginal costs of hospital resources and social sick pay. It showed that the hospital resources spent on the ten groups, which represent half of the postoperative wound infections in Denmark, amounted to approximately 0·5% of the annual national hospital budget. This stratified model creates a better basis for selecting groups of operations which need priority in terms of preventive measures.

An investigation into two cases of post-operative Bacillus cereus meningitis revealed that hospital linen laundered by a batch continuous washing machine was heavily contaminated by B. cereus spores. The washing machine, detergents, other chemical additives and the water supply were eliminated as the source of contamination.

It was found that the linen introduced into the washing machine had a high B. cereus spore content and that this was still present after the wash process. The spores were not killed by either the heat disinfection stage of the wash or the addition of chemical disinfectants and were not removed by the dilution in the process.

The multiplication of B. cereus was thought to have occurred on used, damp linen stored in plastic bags, particularly when ambient temperatures were high. An increase in the water flow through the washing machine was the only measure associated with a decrease in B. cereus on laundered linen.

Between 1966 and 1991, melioidosis, a disease caused by Pseudomonas pseudomallei that is mostly confined to tropical regions, occurred in farm animals and a farmer in temperate south-west Western Australia. Using an Escherichia coli probe containing a ribosomal RNA operon, P. pseudomallei DNA from isolates from 8 animals, a soil sample and the human case showed an identical ribotype on Southern blotting. The ribotype was different from the 3 commonest ribotypes seen in tropical Australia. This molecular typing supports the theory of clonal introduction of P. pseudomallei into a non-endemic region, with environmental contamination, local dissemination and persistence over 25 years. As melioidosis is often fatal in humans, such persistence in a temperate region is cause for concern.

To assess unfiltered drinking water as a source of cryptosporidium infection in patients with the acquired immunodeficiency syndrome (AIDS) the prevalence of cryptosporidiosis among persons with AIDS in Los Angeles County was assessed by water service area. One water distributor, serving approximately 60% of the county's residents (area B), has consistently employed filtration. The other company, which serves the remainder of the county (area A), did not institute nitration until mid-December 1986. This difference provided a ‘natural experiment ’ in which to assess the effect of municipal water filtration on the level of cryptosporidiosis among persons with AIDS. The prevalence of cryptosporidiosis among AIDS patients was compared for the two water service areas for the time period (1983–6) preceding the implementation of filtration in area A. From 1983 to 1986 the age-standardized prevalence of cryptosporidiosis among AIDS patients was 32% lower in area A (4·2%), which received unfiltered water, than in area B (6·2%). Following addition of filtration in area A, the prevalence of cryptosporidiosis among AIDS patients decreased by 20%; however, a decline, of 47%, was also observed in area B. The similar baseline levels of cryptosporidiosis and the corresponding post-filtration decline in both areas suggest that filtration had no effect on levels of cryptosporidiosis among persons with AIDS. Thus it does not appear that municipal drinking water is an important risk factor for cryptosporidiosis in AIDS patients residing in Los Angeles County.

Multilocus enzyme electrophoresis was used to divide 124 Australian isolates of Streptococcus suis type 2 into 17 electrophoretic types (ETs). Isolates in ET 1 were the most frequent cause of disease amongst Western Australian pigs, but isolates of ET 8 were more commonly associated with disease in other Australian states. Multiple isolates from 10 of 19 farms all belonged to the same ET, whilst isolates from the other farms belonged to between 2 and 4 different ETs. Some isolates could be differentiated further by DNA restriction endonuclease analysis, whilst others with the same restriction pattern were located in different, but closely-related ETs. Fourteen isolates were tested for their virulence in mice. Most caused disease if given in high numbers, but isolates in ET 1 were virulent at lower dose rates. This virulent clone also was distinguished by the fact that 80% of isolates produced extracellular factor (EF).

Carrion is a major source of botulinal toxin for animals. A type D strain of Clostridium botulinum differed from type A and B strains in producing (1) much higher concentrations of toxin in putrefying mouse carcasses at several different temperatures over a period of 35 days, (2) toxicity that sometimes persisted in mouse carcasses for at least a year, and (3) mouse carcasses with exceptionally high oral toxicity. Fish carcasses were much less favourable than mouse carcasses for type D toxigenesis.

The study, together with earlier studies on types C and E, indicated that carrion contaminated with C. botulinum type C or D is likely to be particularly dangerous for animals that may ingest it. This accords with the observation that carrion-transmitted botulism in animals is usually caused by type C or D.

In November and December 1992, an outbreak of parvovirus B19 infection occurred among patients and staff on an adult mixed surgical ward at a large hospital in London. Three patients and 15 staff members were serologically confirmed as acute cases. The attack rate among susceptible members of staff was 47%. In those infected, arthralgia (80%) and rash (67%) were the most common symptoms. Of six susceptible in-patients on the ward, three became infected. One of the in-patients who had carcinoma of the mouth was viraemic for more than 10 days with marrow suppression resulting in the postponement of chemotherapy until intravenous immunoglobulin was given and he was no longer viraemic. Control measures taken included closure of the ward to new admissions, transfer of only immune staff to the ward, and restriction of the ward nursing staff to working only on that ward. Although no specific exposure was conclusively identified as a risk factor, there was a suggestion of an increased risk of acquiring parvovirus B19 infection among those staff who did not adopt strict hand washing procedures after each physical contact with a patient (RR = 2·33; P = 0·07). Knowledge of parvovirus B19 among interviewed health care workers was poor: only 42% reported knowing about parvovirus B19 and only 38% could name a patient category at risk of a severe outcome following infection. This is the first report of a nosocomial outbreak affecting an adult ward and of possible transmission of parvovirus B19 infection from staff to in-patients. Hospital control of infection teams should include parvovirus B19 in their outbreak containment plans.

An outbreak of measles occurred in a community school and the surrounding area in Crowborough, East Sussex, UK, from December 1992 to February 1993. There were 96 suspected cases reported: 66 cases among 1673 students at one school and 30 community cases. The majority of suspected cases were in those aged 11–17 (78%), 2 cases occurred in infants < 1 year old and 8 cases in adults aged 18 years or over. Data collected on 60 (91 %) of the 66 suspect school cases showed 56 (93%) had an illness which met a case definition of measles. Eighteen had confirmatory IgM measles antibody. Two cases were hospitalized. The local percentage uptake for measles immunization for the school age years affected varied between 64 % and 84 %. A survey of parents showed that approximately 74% of the students attending the school had a history of measles immunization. The immunization rates reported by parents for children who developed measles was 21 %. (29 % based on GP records) compared with 77 % for those who remained well. Vaccine efficacy was estimated to be 92%. This outbreak, along with others recently reported in older unimmunized children in the UK, reinforces the need for catch-up immunization programmes to reach this susceptible group of adolescents.

In an outbreak of measles in North Wales centred on a secondary school in 1991, 74 cases occurred over a period of 51 days. Before the outbreak started, 27 % pupils did not have a history of measles or immunization and were considered susceptible. Active case rinding and identification and vaccination of susceptible contacts commenced after the fourth generation of cases and further reduced the pool of susceptible schoolchildren from 17%, at the onset of the vaccination campaign, to 8%. A fifth generation of cases did not occur. Delays in diagnosis (mean 2·8 days) and notification (mean 6·1 days) hampered control. There was no evidence of primary vaccine failure (observed vaccine efficacy 97%). Sixty-nine (93%) cases were considered preventable. Reasons for the apparent success of the intervention are discussed.

This paper reports the development and evaluation of serological tests for the differentiation of antibodies in animals infected with capripox and parapox viruses. Agar-gel immunodiffusion tests using sera from sheep with naturally-acquired infections and from sheep experimentally inoculated with orf or capripox viruses showed cross reactions. Virus-specific antibody responses to structural proteins of the viruses were analysed by Western-blot analysis. This analysis readily differentiated the infections as either capripox or contagious pustular dermatitis. The antibody responses to the 32 kDa and 26 kDa proteins of capripox virus provided a firm basis for differention.