A new scheme for phagetyping campylobacters has been evaluated using strains isolated from five outbreaks. The phagetyping results have been compared with the results of Penner serotyping, Lior serotyping and Preston biotyping. Phagetyping recognized the causative strains in all of the incidents and also differentiated these strains from animal and environmental strains isolated during these investigations. In some outbreaks phagetyping proved to be more discriminatory than serotyping or biotyping, e.g. strains of Penner serotype 2, and serogroup 4, 13, 16, 50 were subdivided by this method. Phagetyping is to be recommended for typing strains from outbreaks and although the results indicate that it may be used alone we advocate that it should be used in conjunction with one of the established typing methods.

Chickens given orally at 4 days of age a smooth spectinomycin resistant mutant (Spcr) of Salmonella typhimurium strain F98 excreted the organism in their faeces for approximately 4 weeks. Following oral administration of a nalidixic acid resistant (Nalr) mutant of the same strain 4 weeks later when later when the chickens had virtually cleared themselves of the first infection, these chickens excreted far fewer salmonella organisms and for a shorter time than did a previously uninfected control group of chickens which were infected at the same time with the Nalr mutant. Chickens inoculated intramuscularly at 4 days developed a similar immunity to challenge and also excreted the immunizing strain in their faeces. In contrast intramuscular inoculation or incorporation into the food of formalin-killed S. typhimurium organisms had little lasting effect on the faecal excretion of the challenge strain. Two attenuated mutants of strain F98 Nalr were produced: one was a rough strain produced by lytic bacteriophage and the other was an aro A auxotrophic mutant which had been cured of the 85 kilobase–pair virulence–associated plasmid. These mutants were avirulent for chickens, mice, calves and man and when ingested by human volunteers did not persist in the faeces. When inoculated intramuscularly into chickens they produced an early reduction in faecal excretion of the challenge strain (Spcr) which was not maintained. Oral administration of both strains produced reductions in faecal excretion of the challenge strain. This was much more noticeable with the rough strain which was itself excreted for a much longer period than the parent strain.

The aim of this study was to determine what weaning foods and food preparation practices expose children to a high risk of diarrhoeal disease through exposure to a contaminated diet. Bacterial contamination of 897 food and 896 drinking water samples was assessed in a water and santitation intervention project.

The geometric mean of faecal coliforms per g or ml was 7·5 x 103 in left-over rice, 1·4 x 102 in other types of boiled rice, 2·5 x 102 in milk, 4·8 in household drinking water, and 3·5 in bread. Multiplication of faecal coliforms occurred when there was a delay of more than 4 h between preparation and consumption of food. All samples were more contaminated in the rainy than in the dry season. Strategies to reduce contamination should therefore focus on ‘wet’ foods, early consumption after preparation, and re–heating of left–over foods. Understanding the reasons for the faulty practices is also essential to the formulation of effective measures.

In March 1988, there was an outbreak of infection by a strain of Salmonella saint-paul with a distinctive antigenic marker. A total of 143 reports were received between 1 March and 7 June. Preliminary investigations suggested that raw beansprouts were a possible source of infection and a case-control study confirmed the association. S. saint-paul of the epidemic type was isolated from samples of beansprouts on retail sale in different cities in the United Kingdom and from mung bean seeds on the premises of the producer who was most strongly associated with cases. In addition, Salmonella virchow PT34 was isolated from samples of raw beansprouts and was subsequently associated with seven cases of infection. Four other serotypes of salmonella were also isolated from beansprouts. On 8 April the public were advised to boil beansprouts for 15 seconds before consumption, and the premises of the one producer associated with many cases were closed. As a result of these actions there was a significant decrease in the number of infections with S. saint-paul.

Salmonella enteritidis PT4 was found to be more resistant to heat in egg than some other common egg-associated salmonellas. This organism was significantly more heat sensitive than S. senftenberg 775W, however, and should not survive in pasteurized liquid egg.

The bacteriological quality of 198 ripened soft or semi-soft goat cheeses obtained from dairy farms and the retail trade was investigated. The cheeses were examined for total counts of aerobic bacteria, coliform bacteria (37 and 44 °C respectively), enterocoeci, coagulase positive staphylococci, Bacillus cereus and Clostridium perfringens. Cheeses obtained from dairy-farms were also determined for pH value. In terms of all tests performed, cheeses made of heat-treated milk with starter culture had the best prospects for fulfilling the criteria for 'fit for consumption '. Cheeses made of raw milk without starter culture made up the most unsatisfactory group from a food-hygiene point of view. Bacteriological guidelines for on-farm manufactured goat cheese are suggested.

Oral administration to newly hatched chickens or to chicks up to 5 days of age with an avirulent, rough, spectinomycin–resistant mutant of Salmonella typhimurium strain F98 inhibited the colonization of a nalidixic acid–resistant mutant of the same strain administered by the same route 1 day later. The second strain passed rapidly through the alimentary tract and persisted in the caeca of only a few chickens. Resistance to colonization did not develop until 24 h after inoculation of the first strain but was still evident if the second strain was inoculated up to 7 days later. Resistance occurred in 5 different breeds of chicken and in chickens reared on 5 different diets. Protection was evident against a very high challenge dose and could be produced by the introduction of small numbers of the first strain. Pre–colonization of chicks with the first strain of F98 reduced faecal excretion of the second strain over many weeks, whether chickens were challenged directly or by contact with other infected chickens. The rough strain F98 produced protection against only a few S. typhimurium strains and not against other serotypes. However, strains of S. infantis and S. heidelberg, chosen because they colonized the chicken alimentary tract better than did F98, produced inhibition of a wider range of serotypes.

A quantitative carbon source growth assay, comprising ten carbon sources, was used to compare acinetobacter strains from three hospitals. The strains had been obtained during episodes of increased prevalence of isolations and were, for each hospital, assumed to be epidemiologically related. This assumption was supported by the electrophoretic protein profiles of the strains. Univariate analysis of growth data showed significant differences between strains from the three hospitals. Moreover, cluster analysis revealed that the major pattern in the data was related to the epidemiological origin of the strains. Exceptions to the epidemic-related pattern were observed. Thus, apart from epidemiological factors, other factors might contribute to carbon source growth profiles of the strains. It is concluded that the carbon growth assay may be useful to distinguish roughly between acinetobacter strains from different sites of origin. Further studies are required to analyse additional factors which influence carbon source growth of strains.

Plasmid profile typing has been used to subdivide phage-type 49 of Salmonella typhimurium, the most common phage type in humans in England and Wales since 1985. Twenty profile patterns have been identified in 350 strains examined.

Four profile patterns have been identified in 143 isolates from patients infected in 33 epidemiologically unrelated incidents and two patterns have predominated, ST49:62 and ST49:62,1. These patterns were also common amongst S. typhimurium phage-type 49 isolated from cattle and poultry; however ST49:62 was more common in bovines whereas ST49:62,1 predominated in poultry. S. typhimurium phage-type 49 with a different profile pattern, ST49:62, 3, was responsible for a large outbreak in London in 1988 which was traced to mayonnaise made from eggs supplied by one producer. Plasmid profile typing can now be regarded as a method of supplementing phage typing in investigating outbreaks caused by this organism.

Horizontal transmission of Campylobacter jejuni was investigated in campylobactor–free broiler chicks. One hundred and twenty chicks housed individually, were provided with water containing 102−109 c.f.u./ml C. jejuni. Colonization was rapid [47 of 73 (64 %) positive cloacal cultures within 3 days and 65 of 73 (89 %) within 7 days], depenedent on C. jejuni–contaminated water or colonized seeder chicks. Transmission occurred in 2–7 days concurrent with a gradual increase of C. jejuni in litter, water and feed. Environmental samples were culture–negative within 3 days following removal of colonized chicks. Treatment of 1–day–old chicks with adult caecal microbiota did not affect colonization. Treated and control chicks were all C. jejuni–positive within 3 days of seeder challenge.

We describe the isolation of a new set of phages for typing Staphylococcus epidermidis. One hundred and eighty-two phages were obtained from S. epidermidis strains of human origin. Twelve phages were selected according to their potency and their lytic activity studied. Twenty phages of the Dean and Williams' set were also studied.

Phage-typing was undertaken at 100 × RTD, 1000 × RTD and after heat treatment at 48 °C. When the two sets of phages were compared separately similar figures were obtained. When the two typing sets wrere combined, the percentage of typability for the 182 bacterial strains increased to 29⋅1% using 1000 x RTD and to 75⋅3% after heat treatment.

Twenty–four cultures comprising 20 clinical isolates of ‘Klebsiella aerogenes’ from two hospitals, a reference strain of ‘K. aerogenes’ and the type strains of three other Klebsiella species, were characterized by one–dimensional sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) of whole–cell proteins. The protein patterns were highly reproducible and were used as the basis of a numerical analysis which divided the clinical isolates into 12 protein types. Comparison with established typing methods indicated that the level of discrimination of SDS–PAGE was similar to that achieved with conventional typing methods but the strains were grouped differently. Protein typing sub–divided five serotype K3 isolates that could also be distinguished by phage typing. Conversely, three strains of protein type 11 were clearly distinguishable by both serotyping and phage typing. We conclude that high–resolution SDS–PAGE of proteins provides an effective adjunct to other methods for typing isolates of ‘K. aerogenes’.

This study examined the role of food and water contamination in a health impact evaluation of a water and sanitation intervention project. Although lower diarrhoea rates were found in the improved area no consistent difference in food and water contamination was observed between areas. Furthermore, no relationship was found between contamination and diarrhoea in either area, even after controlling for the nutritional status of children. These results imply that other vehicles of transmission might be more important than food and water in diarrhoeal transmission. The focus of interventions should therefore be on changing behaviours to improve overall hygiene.

The incidence of beta-haemolytic non-Group A streptococci (BHNAS) in the throats of a paediatric population was examined over a 1-year period. There was minimal seasonal fluctuation of Lancefield groups including species and biotypes within Groups C and G streptococci. A trend of increasing incidence with age of Streptococcus anginosus (‘Streptococcus milleri’) (possessing Groups C and G Lancefield antigens) was evident. A clinical impression of streptococcal pharyngitis was more common in patients with large-colony Groups C or G streptococci isolated from their throats compared with those patients where other BHNAS were isolated. This study is requisite to the planning of case control studies which are required to test the association of BHNAS (especially Groups C and G subgroups) and pharyngitis.

Five cases of clinical Q fever were identified amongst students and staff of a Somerset secondary school between 23 October 1987 and 21 December 1987. Five goats which were kept at the school were found to have antibodies to Coxiella burnetii phase II.

A cross-sectional study was conducted at the school in July 1988. A single CF test was used to identify evidence of prior infection, and a self-administered questionnaire was used to collect data on exposure variables and illness during 1987.

Four hundred and ninety-nine eligible subjects took part in the study, and serological information was obtained from 461 of these. Eighty-seven subjects (18·9%) had CF titres of 20 or greater. It was estimated that only 1 in every 30 individuals with evidence of past C. burnetii infection had been recognized as a clinical case of Q fever.

Antibody positive subjects were more likely to have been off school sick and to report having suffered chest pain than negative subjects.

Contact with school animals, specifically cleaning the school poultry, collecting their eggs and visiting a school goat on the day of kidding, was associated with the presence of antibodies to C. burnetii. However a large proportion of the antibody positives (24·2%) had no known contact with the school animals. Spread of organisms, either wind-borne or in straw or manure, may have been responsible for the high prevalence of unexplained infection.

Spirochaetal bacteria were isolated from the faeces of 11·4% of 1000 hospital patients and 26·7% of 292 healthy local nationals in the Muscat area of the Sultanate of Oman. A case-control study of patient records showed the isolation of the spirochaete to be associated with Omani nationality, age in excess of 2 years and attendance at self-referral health-care facilities. No association was found with symptomatic intestinal disease or microscopic abnormalities of the stool.

Stool specimens from 631 children with acute diarrhoea and from 277 healthy controls were tested for the presence of non-enteropathogenic, non-enterotoxigenic Escherichia coli strains which mediated mannose-resistant haemagglutination of human erythrocytes (MRHA + ). Fifty-nine (34·9%) of 169 isolated MRHA + strains but none of 210 MRHA - strains exhibited diffuse adherence (DA+) to HEp–2 cells. DA+ strains were found in 37 (5·9%) children with diarrhoea and in 22 (7·9%) controls. MRHA + /DA + strains in comparison to MRHA + /DA - strains significantly less frequently expressed P fimbriae (10·7 vs. 73·6%), haemolysin production (12·5 vs. 63·2%), and MRHA of other species erythrocytes (21·4 vs. 84%).

These data demonstrate that E. coli which exhibit the diffuse pattern of adherence to HEp–2 cells also cause MRHA of human erythrocytes. Since these strains were found with similar frequencies in children with and without diarrhoea it seems that DA is not a marker of enteropathogenicity of E. coli.

A limited, randomized, blind, placebo-controlled trial of Q fever and influenza vaccines has been conducted in three Queensland abattoirs on a sequential analysis design. Ninety-eight subjects were given Q fever vaccine and 102 influenza vaccine. Q fever cases were observed in unvaccinated workers in all three abattoirs during the period of observation.

A total of seven Q fever cases in one group, one more than the number required to achieve statistical significance between the two vaccine groups, was reached after 15 months with the cases coming from two of the abattoirs. These Q fever cases were in the group which had been given influenza vaccine and none in that given Q fever vaccine.

Symptomless seroconversion rates of 24% were found in the remaining influenza virus vaccinees, and those without immunity were given Q fever vaccine.

Human respiratory tract chlamydial infections have been studied in Cambridge-shire for many years, but until recently we have been unable to distinguish between infection with Chlamydia psittaci Or Chlamydia pneumoniae (TWAR). In this study, we have employed the micro-immunofluorescence (micro-IF) test for this purpose and to look for the relative incidence of C. psittaci and C. pneumoniae infections in Cambridgeshire. Among 50 patients with community-acquired respiratory tract symptoms whose serum samples had Chlamydia complement fixation test titres ≥ 64, 25 had evidence of recent C. psittaci or C. pneumoniae infection. Nineteen (76%) of the 25 patients had evidence of recent C. psittaci infection and of these 16 (84%) had recently had contact with birds. Six patients (24%) had evidence of recent C. pneumoniae infection, and of these, only two (33% had recently had contact with birds). While C. psittaci was grown from several of the birds associated with human C. psittaci infection, it was not cultured from any of the birds in contact with the two human C. pnemoniae cases.

During the period 1981–8 a clinical trial of a Q fever vaccine (Q-vax; Commonwealth Serum Laboratories, Melbourne) has been conducted in abattoir workers and other at-risk groups in South Australia. Volunteers in four abattoirs and visitors to the abattoirs were given one subcutaneous dose of 30 μg of a formalin-inactivated, highly-purified Coxiella burnetii cells, Henzerling strain, Phase 1 antigenic state, in a volume of 0·5 ml.

During the period, over 4000 subjects have been vaccinated and the programme continues in the abattoirs and related groups. ‘Common’ reactions to the vaccine comprised tenderness and erythema, rarely oedema at the inoculation site and sometimes transient headache. Two more serious ‘uncommon’ reactions, immune abscess at the inoculation site, were observed in two subjects, and two others developed small subcutaneous lumps which gradually dispersed without intervention.

Protective efficacy of the vaccine appeared to be absolute and to last for 5 years at least. Eight Q fever cases were observed in vaccinees, but all were in persons vaccinated during the incubation period of a natural attack of Q fever before vaccine-induced immunity had had time (≥ 13 days after vaccination) to develop. On the other hand, 97 Q fever cases were detected in persons working in, or visiting the same abattoir environments.

Assays for antibody and cellular immunity showed an 80–82% seroconversion after vaccination, mostly IgM antibody to Phase 2 antigen, in the 3 months after vaccination. This fell to about 60%, mostly IgG antibody to Phase 1 antigen, after 20 months. On the other hand, 85–95% of vaccinees developed markers of cell mediated immunity as judged by lymphoproliferative responses with C. burnetii antigens; these rates remained elevated for at least 5 years.

The Q fever vaccine, unlike other killed rickettsial vaccines, has the property of stimulating long-lasting T lymphocyte memory and this may account for its unusual protective efficacy as a killed vaccine.