Since the low point of 1977 the incidence of infection attributed to Salmonella typhimurium in England and Wales has shown a steady increase with a total of 4956 cases reported in 1982 (OPCS, 1985). Although the number of general outbreaks and family outbreaks increased by 24 % and 54 % respectively between 1981 and 1982, the greatest increase (55%) was in the number of sporadic cases reported (PHLS, 1984). The cause of the recent increase in human infection is not known but may be associated with bovine infection and an explanation for the rise in sporadic cases could be that they comprise unrecognized outbreaks due to common food products distributed over wide geographical areas for long periods of time because of deep freezing (Galbraith, 1985). This hypothesis has prompted the Communicable Disease Surveillance Centre to mount a case-control study comparing sporadic cases of S. typhimurium infection with an unaffected control group in several parts of the country to find the vehicles of infection. Such an approach requires precise strain identification and detailed epidemiological information.

Eight monoclonal antibodies have been derived from Balb/e mice hyperimmunized with the purified flagella from Campylobacter jejuni strain 81116. These monoclonal antibodies are directed against flagella as demonstrated by reaction in ELISA against flagellate and aflagellate antigens, radio-immunoprecipitation and electro-immunoblotting techniques. Some of the antibodies react with a 60K minor protein as well as the 62K flagella protein. This protein may be related to an antigen expressed on the surface of the organism and detectable by immunogold labelling with one of the monoclonal antibodies.

None of the antibodies causes the aggregation of bacteria or inhibits bacterial motility, unlike polyclonal anti-flagella antiserum. Moreover, none of the antibodies tested protected infant mice from colonization with C. jejuni strain 81116 even though partial protection (28%) was observed with syngeneic anti-flagella antiserum. Absence of protection is probably due to the cryptic nature of the flagella epitopes investigated or lack of antibody activity in the gastrointestinal tract.

Nine monoclonal antibodies directed against the flagella of Campylobacter jejuni strain 81116 have been investigated for serotypic and cross-reacting activity using a panel of 17 Penner serotype strains of C. jejuni. Four monoclonal antibodies were exclusively specific for serotype-6 strains, which was the serotype of C. jejuni strain 81116. Two monoclonal antibodies cross-reacted with all the flagellated strains of C jejuni tested. One of these cross-reacting monoclonal antibodies, CF5, was found to react with all other Campylobacter species except C. sputorum bulbulus but it did not react with other bacterial entcropathogens. An antigencapture ELISA technique was established, using this monoclonal antibody, which could detect flagellar antigen in human faecal material. These anti-flagella monoclonal antibodies therefore may be valuable in the diagnosis and serotyping of C. jejuni in clinical material.

An enzyme-linked immunosorbent assay (ELISA) for the rapid diagnosis of antibiotic-associated colitis (AAC) is presented. Commercially available antisera to Clostridium difficile toxins contain antibodies to other antigens found in non-toxigenic C. difficile and other bacteria. Removal of these unwanted antibodies by absorption increased the specificity of ELISA for detection of C. difficile toxins. Specimens tested included 40 faecal extracts positive for cytotoxicity from cases of AAC, 30 diarrhoeic and 30 well-formed stools negative for cytotoxicity and 50 culture filtrates of toxigenic and non-toxigenic C. difficile and other clostridial species. Use of absorbed sera reduced false-positive reactions observed with faecal specimens frqm 23 to 8 %. About 90 % of specimens that were positive by the tissue culture cytotoxicity test were positive by ELISA using the absorbed sera. The relative merits of ELISA and other methods for the rapid diagnosis of AAC are discussed.

A cross-sectional study of 447 laying hens (age range 0–65 weeks) and a longitudinal study of 164 similar birds showed that Campylobacter jejuni was not present in the faeces of newly hatched chicks, but that colonization arose after 5–9 weeks. A survey of 250 broilers obtained from four breeders showed that all were negative for C. jejuni before and after slaughter at the age of 5 weeks. Once C. jejuni had appeared in a flock, it rapidly spread to virtually all birds, but at the age of 42 weeks only 20–46% of birds remained colonized, possibly as a result of having developed immunity. Birds housed in the protective environment of a laboratory still became colonized (after 9 weeks). The mode of infection is unknown, but water and food were bacteriologically negative and were deemed to be unlikely sources. Transmission via attendants, flies or other insects remain possibilities. It is concluded that prevention of colonization might be possible within the life-span of broiler chickens (5–7 weeks), but that it would be difficult to extend this period. There is a need to define how colonization arises so that the feasibility and cost of possible preventive measures can be assessed.

Intraperitoneal vaccination of female mice, before mating, with a whole cell, heat-killed (62 °C) vaccine of Campylobacter jejuni allowed the mother to confer immunity to her young, challenged orally 4–6 days after birth with the homologous strain. There was no protection against a strain of another serotype. Heating the vaccine to 100 °C destroyed its protective properties. A vaccine prepared from an anagellate variant of the original strain was as protective as the original vaccine against challenge with the flagellated strain. Anti-flagellar serum antibody titres of the dams did not correlate with protection of their young.

This report presents the parasitological, bacteriological, mycological and physicochemical data obtained from both surface water and beach sand of a lake used for water sports. These show that the lake is contaminated in both winter and spring by water which overflows from the River Maine, and is self-purified by a mechanism of ‘lagunage’. In summer signs of pollution are at their lowest level although use of the complex is at its peak. Conversely, the amoebic flora, which is independent of the usual criteria of pollution, predominates in summer, and serves as a marker for the need for increased surveillance. The sand of the beaches does not appear to show any infectious hazard. Environmental pressure will doubtless change these data over a period of time, and it is planned to monitor this.

The role of broiler eggs in the transmission of Campylobacter jejuni to broiler grow-out flocks was investigated. Six breeder flocks supplying broiler eggs to hatcheries were examined for cloacal carriage of C. jejuni. Of 240 birds tested, 178 (74%) were C. jejuni-positive. Eggs from these birds examined for C. jejuni penetration of the egg shell indicated that 185 of 187 were campylobacter-free. Eggs from breeder flocks of unknown C. jejuni status were also examined for C. jejuni shell penetration. C. jejuni was not isolated from 142 eggs examined. A further 193 hatchery eggs incubated and hatched in the laboratory were campylobacter-free. Six farms containing the progeny of C. jejuni-positive breeder flocks were monitored. Eight hundred and forty birds from 14 flocks m these grow-out farms were campylobacter-free during their 6-week grow-out period. Experimental egg-penetration studies indicated that C. jejuni transmission via the egg is not easily effected. Of 257 eggs surface-challenged with C. jejuni, 162 hatched; all were campylobacter-free. Of 167 eggs injected with C. jejuni, 12 hatched; 2 of these were colonized with C. jejuni. Our data do not support a role for vertical transmission of C. jejuni in commercial broiler production.

The isolation rate for Clostridium difficile in diarrhoeal stools was investigated in patients from general practice and community health centres over a 14-month period. C. difficile or its cytotoxin was detected in specimens from 89 (4·7 %) of 1882 patients studied and accounted for 30·3 % of all enteropathogenic micro-organisms isolated. Overall C. difficile was second only to Giandia lamblia in frequency. Recovery rates in the different groups of patients surveyed varied from 3·6 to 27·5 %. The relationship between stool culture results and stool cytotoxin assay also varied considerably between groups of patients studied. Coincident infections with a variety of enteropathogenic bacteria and intestinal parasites were diagnosed in 14 of the 89 patients. It was concluded that laboratories servicing this type of practice should be aware that C. difficile may be a cause of diarrhoea. An adequate clinical history should facilitate proper processing of the specimen.

The brucellin skin test and the lymphocyte transformation test were compared in heifers infected with virulent Brucella abortus strain 544, heifers vaccinated against brucellosis and unexposed cattle. Results of the in vitro lymphocyte transformation test were consistently positive for all 9 Brucella-infected heifers while the skin test was consistently positive for 6 of the 9 heifers. In 7 heifers repeatedly vaccinated with B. abortus strain-19 vaccine the in vitro test classified 3 animals as positive whereas the skin test identified all the animals as infected during most of the experimental period. Four heifers injected with a single dose of B. abortus strain 19 were consistently negative to the lymphocyte transformation test while the skin test classified all the animals as infected during most of the experimental period. The skin test gave strong reactions indicative of Brucella infection in heifers vaccinated with ‘Duphavac’ and ‘Abortox’ vaccines whereas the lymphocyte transformation test was consistently negative with these vaccines. The two tests were negative in unexposed cattle. It was concluded that the in vitro test correlated better with Brucella isolation than the in vivo test did and that the lack of agreement between the results of the two tests is likely to be due to the different antigens used in the assays.

Simultaneous oral administration of broth cultures of three strains of Escherichia coli isolated from sewage and an abattoir strongly inhibited the colonization of a subsequently administered strain of Salmonella typhimurium. The three strains were protective against the S. typhimurium strain under a variety of conditions: in different breeds and in chickens fed different diets. The strains were not equally effective against other salmonella strains. Oral administration of the strains produced a statistically significant reduction in the excretion of the S. typhimurium strain over a period of 7 weeks.

A microbial survey of Sri Lankan desiccated coconut has been made on material purchased in supermarkets in Sheffield or on material obtained directly from the processing company. The total viable count (TVC) was reduced by spoilage and pasteurization from 104/g to 103/g. Most samples contained low levels of coagulase-positive Stephylococcus aureus suggesting that this commodity had been handled during production. One focus of contamination with Aspergillus flavus was found for each 8·34 g of desiccated coconut (mean contamination). The number of bacteria and moulds in spoiled coconut was significantly lower than that in coconut obtained from the processor or purchased from retail outlets. It is suggested that the accumulation of free fatty acids, aliphatic methyl ketones and secondary alcohols produced during fungal spoilage has had a bactericidal and fungicidal effect. The use of microbial specifications for foods is questioned in situations where there is evidence of microbial spoilage having taken place.

An enzyme-linked immunosorbent assay (ELISA) was developed to detect IgG antibodies to diphtheria toxin in human serum. Serum samples obtained from 557 normal persons aged 1–65 years from different areas in New Zealand showed maximum antibody levels in the 1–9 years age group (95·1%) and the least in the 60–65 years age group (38·1%). The indirect ELISA is suitable for sero-epidemiological survey study as it is simple to perform, economical and precise.

Susceptibility studies were undertaken to determine the response of some South African wild rodent species to experimental plague (Yersinia pestis) infection.

A degree of plague resistance was found in three gerbil species captured in the plague enzootic region of the northern Cape Province, these being the Namaqua gerbil, Desmodillus auricularis, (LD50 1 × 106 organisms), the bushveld gerbil, Tatera leucogaster, (LD50 9·1 × 105) and the highveld gerbil, T. brantsii (LD50 4 × 102). Animals from a population of the four-striped mouse, Rhabdomys pumilio, captured in the plague area of Port Elizabeth, proved moderately resistant to experimental plague infection (LD 50 1·3 × 104) while those from another population of the same species captured in a plague-free area of the Orange Free State were extremely susceptible (LD50, 5 organisms). The response of both populations however was a heterogeneous one. Marked differences in susceptibility were also found between two populations of multimammate mice, Mastomys natalensis (2n = 32) although both originated from areas outwith the known distribution of plague in southern Africa.

The 50% infectious dose was relatively high in T. leucogaster (3·2 × 102) and D. auricularis (1·7 × 103), but was low (2–16 organisms) in the other rodent species tested.

The plague antibody response, determined by enzyme-linked immunosorbent assay (ELISA), was extremely short-lived in T. leucogaster, only 10% of inoculated animals remaining seropositive at low titres after 11 weeks. Antibodies persisted for only slightly longer in the sera of T. brantsii which were reinoculated with 2 × 103 plague organisms 6 weeks after initial challenge.

The demonstration of the existence of both susceptible and resistant populations of R. pumilio and M. natalensis indicates that these species must be considered as potential plague reservoir hosts in parts of South Africa.

The results suggest that resistance to plague infection in previously epizootic hosts in the northern Cape Province such as Tatera sp. and D. auricularis has arisen through continual selective pressure of the organism. If the findings are applicable to gerbil populations in other plague enzootic regions of South Africa it is probable that acquired plague resistance has been responsible for the absence of gerbil epizootics and consequently for the dramatic decline in human plague outbreaks in South Africa since 1950.

Controlled parallel experiments were performed on the Vienna test model for the evaluation of procedures for hygienic hand-disinfection in three laboratories (Vienna, Mainz, Birmingham). The degerming activity of four procedures, each taking 1 min, was assessed repeatedly and compared with that of a standard disinfection procedure (ST) using isopropanol 60 % (v/v). The mean log reductions (mean log RF) for each procedure were as follows: n−propanol 50% (v/v) 4·85 and 5·14 in Vienna (V) and Mainz (M) respectively, ethanol 70 % (v/v) + chlorhexidinegluconate 0·5% (w/v), 4·01 (V), 3·76 (M) and 4·00 in Birmingham (B). Washing procedures were less effective, mean log RF 's of 3·19 (V), 3·49 (M) and 3·04 (B) were obtained with povidone-iodine soap, and 2·91 (V), 3·37 (M) and 3·27 (B) with a liquid phenolic soap. Analysis of variance on the data from Vienna and Mainz revealed significant differences of means not only between procedures (‘preparations’) but also on repeat testing. To compensate for the influence of variables such as test subjects, laboratory and day, the Vienna test model provides a method of standardization by testing a ST in parallel with the test procedure (P).

Standardization of the results was obtained by pair-wise substraction, log . Analysis of variance on the resulting values demonstrated that comparability of the results between laboratories and on repeat testing was achieved. The relative variation of the measurements within the laboratories ranged from 0·9 to 4·2%. As assessed by power-analysis, a disinfection procedure will be detected as significantly (P= 0·1) inferior to the standard processes in 95 of 100 experiments if it produces a mean log RF that is at least 0·55–0·65 log units smaller than that of the standard.

A disinfectant (2,4,4′-trichloro-2′-hydroxydiphenyl ether: Irgasan, Ciba-Geigy) was incorporated into plastic washers fabricated from ethylvinyl acetate (EVA), polyethylene, polypropylene or TPX. Plastics containing 0·2 and 2% Irgasan gave zones of inhibition on nutrient and blood agar plates seeded with micro-organisms (Staphylococcus aureus, Staph, epidermidis Escherichia coli, Proteus mirabilis or Candida albicans) even after thorough washing. Exceptionally, C. albicans was inhibited only by 2% Irgasan, and EVA gave good inhibition only against the staphylococci. Similar washers of each plastic were implanted subcutaneously into the flanks of rabbits; before insertion each was washed, had thread woven into it and was surrounded by a plasma clot containing 2 × 108Staph. aureus. All the plastics without Irgasan gave rise to abscesses, none of the plastics impregnated with 2% Irgasan did, though from 2 out of 12 sites small numbers of Staph. aureus were isolated at post mortem. Using either clinical or bacteriological criteria, the results were highly significant (P < 0.00001 and P <0.001 respectively), demonstrating the effectiveness of this technique in preventing plastic-associated infection.

Five hundred strains of methicillin-resistant Staphylococcus aureus were tested against various anti-staphylococcal agents. Vancomycin, fusidic acid and fosfomycin were found to be the most effective. Only 1 strain out of 500 was resistant to fosfomycin. Three patients with methicillin-resistant Staphylococcus aureus septicaemia were successfully treated by fosfomycin. We conclude that fosfomycin could be the drug of choice for methicillin-resistant Staphylococcus aureus infection.

Serogroup-specific antigen was extracted from a number of Legionella pneumophila strains and compared with phenol-water extracted lipopolysaccharide on the basis of gel filtration, chemical analysis, SDS-PAGE and reaction with serogroup-specific antibody in immunoblots. Serogroup specificity is apparently borne by the O side-chains of the lipopolysaccharide, which, although smooth in type, partitions in the phenol phase. For four serogroup 1 strains tested, there was no qualitative correlation between O side-chain length and pulmonary virulence for guinea-pigs.

The expression of toxigenicity by Vibrio cholerae, before and after exposure to various conditions of salinity, pH and cation composition and concentration, has been measured. Exposure to these conditions did not select for hyper- or hypo-toxigenic strains. This suggests that toxigenic V. cholerae O 1 are unlikely to lose their toxigenicity when exposed to environmental stress and that V. cholerae toxin production is not a response to the stresses included in this study. These results are consistent with an aquatic reservoir for toxigenic V. cholerae O 1.

The relative efficiencies of three commercially available dehydrated Rappaport–Vassiliadis media have been compared with a similar medium prepared from individual constituents in our own laboratory. An inoculation ratio of 1 : 100 was found to be optimal for each of the media tested. Laboratory produced RV-medium was significantly better than the three commercial preparations after 24 h incubation. However, when the duration of incubation was extended to 48 h, there was no significant difference in the number of salmonella isolates obtained when using our own RV medium and that produced by Oxoid Ltd and Difco Ltd (P > 0·05). All of these three media were, however, significantly more effective than the medium produced by Lab.M.(P <0·01).