Five probable secondary cases of meningococcal disease were identified in microbiology laboratory workers in England and Wales during a 15-year period. All cases had prepared suspensions of Neisseria meningitidis outside a safety cabinet upto seven days before onset of illness. Relative risk in laboratory workers compared with the background adult population was 184 (95% CI 60-431). In view of the potentially serious outcome from this infection, a safety cabinet should always be used when preparing or working with suspensions of meningococci. Vaccination policy for microbiology laboratory workers should be reviewed.

A survey of clinical microbiology laboratories in England and Wales found that in 12% of laboratories a class 1 microbiological safety cabinet was not always used for manipulating suspensions of live meningococci. The recommendation that a safety cabinet should always be used for such purposes needs reiteration and implementation.

Poultry is a source of human campylobacteriosis, but a large continuous source outbreak, heretofore, has not been attributed to both a single source of poultry and single serotype of Campylobacter. Here we report an outbreak of C. jejuni affecting 6 catering college trainees and 13 patrons of a restaurant in southern England. An epidemiological investigation successfully tracked the outbreak source to the farm of origin. Frequency of occurrence of campylobacters and outbreak serotype distribution were determined in index cases, the local population, and local chicken suppliers. The source farm was investigated and the effect of interventions assessed. A single outbreak serotype of C. jejuni was isolated from trainee chefs, patrons, and chicken supplied to the college by Wholesaler A. The Campylobacter isolation rate for Wholesaler A was 89% (98% outbreak serotype), compared to 40% for non-Wholesaler A (10% outbreak serotype). The isolation rate for 14 months averaged 85% (99% outbreak serotype) in chickens grown on two farms (X and Y) supplying Wholesaler A, contributing ∼40% to all local cases. In the research reported here, a specific strain and hygiene practice were found to be important for understanding transmission of Campylobacter from poultry to humans in this outbreak.

Changes in the frequency of serogroup B non serotypable (B:NT) meningococci isolated in England and Wales were investigated by T-track fingerprint analysis, DNA nucleotide sequence determination, and serotyping by whole cell ELISA and dot blot assay. Seventy-three per cent of the isolates designated as B:NT by the Meningococcal Reference Unit (MRU) dot blot assay during 1993-4, expressed variants of the serotyping antigen, PorB, that were serotype 4 by whole cell ELISA. T-track fingerprint patterns of these and other 'serotype 4' isolates revealed five distinct porB alleles which were shown by nucleotide sequence determination to encode different peptide sequences. Differential binding of the 'serotype 4' mAbs MN14G21 and 5DC4C8G8 in whole cell ELISA and dot blot assays was the result, (i) of differences in the peptide sequence of predicted surface loop I and (ii) an amino acid deletion in predicted loop VI of the PorB protein.

A comparative examination of the heat-stable (O) and heat-labile (HL) serogrouping results for 9,024 sporadic human isolates of Campylobacter jejuni revealed conserved associations between specific O and HL antigens (O/HL serovars). Forty-nine percent of the isolates which grouped for both O and HL antigens belonged to one of three serovars: O 4 complex/HL 1 (17.9%), O 1/HL 2 (16.8%), or O 50/HL 7 (14.5%). Other common serovars were O 2/HL 4 (8.3%), O 6/HL 6 (8.1%), O 53/HL 11 (4.5%), O 19/HL 17 (3.3%), O 5/HL 9 (3.3%), O 9/HL 9 (3.2%), and O 23/HL 5 (3.1%). These 10 serovars accounted for 83.1% of the serogroupable isolates. A large number of strains (41.3%) could be typed by only one of the two methods or could not be serogrouped (11%). Strains belonging to three serovars, O 2/HL 4, O 50/HL 7, and O 23/HL 5, were further characterized by combining data from expressed features (O/HL serogroups, phage groups, and biotypes) with restriction fragment length polymorphism genotypes. These polyphasic data demonstrated that within each serovar, individual isolates showed substantial conservation of both genomic and phenotypic characteristics. The essentially clonal nature of the three serovars confirmed the potential of combined O and HL serogrouping as a practical and phylogenetically valid method for investigating the epidemiology of sporadic C. jejuni infection.

Genomic profiles were obtained for 76 strains of Campylobacter jejuni isolated from bacteraemic patients in England and Wales over the period 1981–94. Genotyping was performed by restriction fragment length polymorphism (RFLP) analysis using a random cloned DNA probe, and by ribotyping with a PCR-generated C. jejuni 16S ribosomal DNA probe. Phenotypic characterization was achieved by heat-stable (HS) and heat-labile (HL) serogrouping, and Preston phagetyping and biotyping. The blood isolates were genomically heterogenous, with 24 RFLP/16S profiles occurring within the 76 strains. Forty-four percent of isolates belonged to one of three RFLP/16S genotypes, reflecting the patterns seen in faecal isolates, except that genotypes usually associated with the HS 1 antigen were uncommon. The two most prevalent genotypes, characteristic of HS 2 and HS 4 strains, showed similarity by cluster analysis. Further evidence was seen of associations between phenotypic and genotypic characters within some HS serogroups. Chromosomal profiling by RFLP analysis does not indicate that particular genotypes have a predisposition to invade the bloodstream.

Considerable efforts are being made in the search for suitable candidates for an effective serogroup B meningococcal vaccine, but with limited success. We have identified a novel, high molecular weight antigen of approximately 200 kDa. The antigen was expressed during invasive disease as 100% of convalescent case sera contained antibody compared with approximately 50% of carriers. Many clinical isolates did not appear to express the 200 kDa antigen, but corresponding sera contained antibody, indicating in vivo expression. Antibody to this antigen cross-reacted with meningococci of diverse phenotypes. Further investigation of this antigen is required to determine its potential as a future vaccine component.

Recombinant Escherichia coli LamB proteins containing meningococcal PorA epitopes were used for the analysis of the human antibody response to specific PorA epitopes. Sera from meningococcal cases, carriers and controls were examined by an ELISA-inhibition assay. Antibody to the serosubtype P1.16 epitope was detected with similar frequency regardless of whether recombinant E. coli LamB protein containing P1.16 or SDS-PAGE purified meningococcal class 1 protein (serosubtype P1.16) was used as the antigen.

A novel PCR amplification method is described which is specific for the thermophilic, enteropathogenic species Campylobacter jejuni, Camp. coli and Camp. upsaliensis. Rapid, accurate speciation of amplified strains is possible on the basis of restriction fragment length polymorphisms of PCR products digested with three restriction enzymes, AluI, DdeI and DraI. The sensitivity of detection is 25 cfu in water, and 2 x 10(3) cfu in full cream milk. An epidemiological application of the assay in detecting non-culturable campylobacters from a contaminated potable water supply is described.

The reactogenicity and immunogenicity of a serogroup A and C meningococcal polysaccharide-CRM197 conjugate vaccine was evaluated in 58 infants who received three doses at 2, 3, and 4 months of age. The conjugate vaccine produced few systemic side effects, and local reactions were significantly less common than those produced by the routine vaccinations. The prevaccination geometric mean titers (GMTs) of A and C polysaccharide antibodies were, respectively, 2.8 and 0.6 microg/mL, rising to 21.5 and 38.5 microg/mL by 1 month after the third dose (age 5 months) and falling to 3.1 and 2.2 mircog/mL by 14 months of age. Prevaccination serum bactericidal titers against 2 serogroup C meningococci strains were <1/4 in 49 of 52 infants, rising to a GMT of 1/3082 at 1 month after the third dose and falling by age 14 months to a GMT of 1/10. Thus, this meningococcal conjugate vaccine proved to be safe and immunogenic, inducing high levels of anti-C polysaccharide antibodies that were bactericidal in young infants.

Campylobacter jejuni serogroup reference strains and collections of sporadic and outbreak-associated isolates were examined for restriction fragment length polymorphisms (RFLPs), using C. jejuni random chromosomal and 16S rRNA gene probes. A collection of 48 Penner (HS) and 14 Lior (HL) serogroup reference strains, plus 10 clinical isolates, generated 35 RFLP and 26 ribotype patterns. In combination the two loci generated 48 distinct genotypes. Both probes were able to differentiate between certain random isolates of the same HS/HL serogroups but greater discrimination was obtained with RFLP than with ribotyping. Genotyping distinguished accurately between related and unrelated strains when applied to several outbreaks. Genotypic analysis of C. jejuni by restriction fragment length polymorphisms is a valuable technique for epidemiological typing. Chromosomal variation detected by the two unlinked probe loci provides some information about the genetic relationship between isolates.

A study of Campylobacter jejuni on a broiler chicken farm between 1989 and 1994 gave an estimated isolation rate of 27% (3,304 of 12,233) from a 0.9% sample of 1.44 million broiler chickens from six to eight sheds over 32 consecutive rearing flocks comprising 251 broiler shed flocks. During the study, C. jejuni was found in 35.5% of the 251 shed flocks but only 9.2% (23 of 251) had Campylobacter isolates in successive flocks, with 9 of those 23 sheds having the same serotype between consecutive flocks, indicating a low level of transmission between flocks. Analysis of a systematic sample of 484 of 3,304 (14.6%) C. jejuni isolates showed that 85% were of 10 serotype complexes but 58% were of 3 serotype complexes, indicating a high degree of strain similarity throughout the entire study. The three commonest types were detected in 8 of 32 flocks during the 5-year study period, suggesting an intermittent common external Campylobacter source. This hypothesis was tested by a retrospective cohort analysis of C. jejuni rates and types by reference to hatchery supplier of the 1-day-old chicks. Isolation rates of C. jejuni and frequency distribution of types were determined in 6-week-old broiler chickens identified by the hatchery supplying the original chicks. The isolation rate of C. jejuni in broilers, supplied by hatchery A, was 17.6%, compared to 42.9% (P < 0.0001) for broilers reared from chicks supplied by hatchery B. In two instances, when both hatcheries were used to stock the same farm flock, Campylobacter isolates were found only in those sheds with chicks supplied by hatchery B. Thus, the frequency distribution of Campylobacter types for chickens supplied by the two hatcheries over the 5-year period showed marked dissimilarity. These findings suggest that the isolation rate and type of Campylobacter isolates in broiler chickens was associated with the hatchery supplying chicks. The lack of diversity of types and the intermittent high positivity of sheds is evidence for a common source of C. jejuni introduced by vertical transmission rather than contamination at the hatchery or during transportation.

An international study supported by the World Health Organization comparing monoclonal antibodies for serotyping and serosubtyping of Neisseria meningitidis strains was performed and the results were assessed in 1992. A collection of 6 serotype-specific (1, 2a, 2b, 4, 14, and 15) and 12 serosubtype-specific (P1.1, P1.2, P1.4, P1.5, P1.6, P1.7, P1.9, P1.10, P1.12, P1.14, P1.15, and P1.16) monoclonal antibodies was provided to 11 participating laboratories throughout the world. Monoclonal antibodies were tested on 85 Neisseria meningitidis strains with known reference results. Whole-cell enzyme-linked immunosorbent assay was used for analysis in 10 of 11 laboratories. The sensitivities and specificities of individual serotype- and subtype-specific monoclonal antibodies were evaluated. Differences in individual laboratories and with individual monoclonal antibodies were assessed. Relatively large differences in sensitivities were achieved in individual laboratories. On the contrary, the specificities remained at high levels in all laboratories. The sensitivities of serotype-specific monoclonal antibodies ranged from 72.0 to 100%. Individual serosubtype-specific monoclonal antibodies showed sensitivities ranging from 64.1 to 98.1%. The most frequent reason for the incorrect results obtained with the monoclonal antibodies were false-negative results. The collaborative study demonstrated that some monoclonal antibodies are not very sensitive. Another study to define the most suitable monoclonal antibodies is planned.

An outbreak of 12 cases of meningitis, 11 caused by Neisseria meningitidis serogroup C, occurred at Doomadgee from September, 1990, to April, 1991. The incidence of meningitis was 17.55/10(3) person-years. Only children aged 1-10 years were affected. In October, 1990, or shortly thereafter, 473/509 children aged between 1 and 15 years inclusive had one dose of Mencevax AC. From the time of vaccination until April, 1991, a further eight cases occurred, six in vaccinated children. Vaccine efficacy in 1-15 year olds was calculated as 77%. Despite this, in April, 1991, the prevalence of antibody to group C polysaccharide in vaccinated children (78%) was not significantly different from that in unvaccinated children and adults. 46 nonresponders were revaccinated, and, in February, 1992, 78% had antibodies to group C polysaccharide. In April, 1991, an estimated 3.0% of the population had group C organisms, carriage being directly related to household crowding. In June, 1991, 2 months after mass prophylaxis with rifampicin, none of these individuals were carriers. In October, 1991, the carriage rate of group C organisms was 0.64%. There have been no further cases caused by the epidemic strain. Although uncrowded housing is a basic need, mass chemoprophylaxis and two doses of vaccine for children should be used in similar outbreaks.

Using an infant mouse intranasal infection model, we have compared the virulence of 17 epidemiologically related isolates of Neisseria meningitidis associated with an outbreak of meningococcal disease in Gloucestershire, UK, and one germane isolate. The isolates were all of serotype 15 subtype P1:7, 16 and were identical by restriction fragment length polymorphism analysis, but differed in either (i) whether they were isolated from a case or a carrier, (ii) the presence or absence of group B capsule, or (iii) their lipooligosaccharide (LOS) immunotype. The results indicate that capsule is a major virulence determinant and is required for colonization and hence for invasion. In addition, the LOS L3,7,9 immunotype, when compared to the L1,8,10 immunotype, is a secondary virulence factor which enhances colonization of nasal passages and invasion of the blood stream by both case and carrier isolates. Two case isolates which were unusual in possessing the L1,8,10 immunotype, established invasive infection, but this was associated with a switch to the L3,7,9 immunotype. The results confirm that LOS is a virulence factor for N. meningitidis and that immunotype L3,7,9 is associated with invasive disease.

The age incidence of meningococcal infections occurring between 1984 and 1991 in England and Wales was determined from data submitted with isolates to the Meningococcal Reference Laboratory for England and Wales. The incidence was maximum at 6 months of age and thereafter declined sharply to the age of 4 years. It was followed by a small secondary peak at 17–18 years. There was a relative excess of group B infections in the early months of life and, although group B and group C infections both peaked at 6 months of age, the latter did not decline until after the age of 9 months. Certain strains of meningococci were more likely to be associated with disease in older children and young adults.

The progress in vaccines for Haemophilus influenzae type b infection is followed; it is the disadvantages of pure polysaccharide vaccines that have stimulated the development of the present generation of polysaccharide-protein conjugated vaccines. From extensive clinical trials it is apparent that these are very effective in preventing disease in children. Conjugated haemophilus vaccines were introduced into the routine immunization schedules in the UK in Autumn 1992. Meningococcal A and C polysaccharide vaccines, effective for epidemic disease, are only now being developed in a protein conjugated form with the prospect of protecting young children and producing durable immunity Group B outer membrane-based meningococcal vaccines produce only a low degree of protection and much further work is needed before even the optimum vaccine constituents of this organism can be identified. Vaccines to replace multivalent pneumococcal polysaccharide mixtures are only in the very earliest stages of development.

Campylobacter jejuni, when left on blood agar for prolonged periods, was found to survive better in air than under micro-aerobic conditions. After a period of 2-3 days in air, all strains of C. jejuni examined grew freely in air on subculture, and could be further subcultured apparently indefinitely in air. This adaptation to aerobic metabolism was accompanied by a change in colony morphology and some changes in outer-membrane protein patterns, but no change in serotyping reactions. The ability to colonise mice was unaltered as was the helical morphology of growing cells. The important survival phase of C. jejuni, when outside the animal gut, involves not only a change to coccal morphology but also fundamental changes in the metabolism of the organism. These changes are likely to be relevant to techniques required for culturing C. jejuni from foods and environmental sources.

Examined before subculture, gonococci in 18 urethral exudates collected from different patients were serum-resistant. For 15 exudates, the resistance was drastically reduced by treatment with neuraminidase and by one subculture on laboratory media. It was restored by incubation with cytidine 5'-monophospho-N-acetyl neuraminic acid (CMP-NANA). Electron microscopic examination of gonococci in eight exudates showed a surface structure stained by Ruthenium red which disappeared in most samples when they were treated with neuraminidase. These results were identical with those of previous studies on in vitro grown gonococci which had shown that serum resistance is due to sialylation of a 4.5-kDa conserved component of gonococcal lipopolysaccharide (LPS) by host CMP-NANA, which masks the target site for bactericidal IgM and renders surface LPS stainable by Ruthenium red. The serum resistance of gonococci in the remaining three exudates was not reduced by neuraminidase nor by subculture. The mechanism of this stable resistance is unknown.