Lancefield group A streptococci isolated from recent outbreaks and sporadic cases of scarlet fever were restricted to the following M types 1, 3, 4, 6, 12, 18, 22 and 66. These strains were examined for the presence of streptococcal pyrogenic exotoxins (SPE) types A, B and C by isoelectric focusing in polyacrylamide gels and by immunoprecipitation in agar gels. SPE B was produced by 70% of the strains and SPEC by 40%. SPE A could not be detected in these strains. In contrast, SPE type A was found in 4 of 10 strains, held by the NCTC, that had been isolated before 1940 from patients with scarlet fever. Nine of 12 recent isolates from patients with sore throat uncomplicated by a rash produced SPE C and 4 of these also produced SPE B.

Three of four extreme methods of immunization completely failed to protect mice against challenge with the homologous strain of Fusobacterium necrophorum. Unsuccessful vaccines included (1) broth culture killed by mild heat and emulsified with Freund's complete adjuvant, and (2) a homogenate of heavily infected mouse brains, inactivated by mild heat and given in two doses. Also unsuccessful as a method of immunization was the production of a severe subcutaneous infection with F. necrophorum, followed by curative treatment with metronidazole. Slight but significant protection against subcutaneous challenge resulted, however, from two such infections given in rapid succession. It would appear that the main virulence factors of F. necrophorum are onty weakty immunogenic, and the experiments give little encouragement to the prospect of an effective necrobacillosis vaccine.

The study of Escherichia coli and its plasmids and bacteriophages has provided a vast body of genetical information, much of it relevant to the whole of biology. This was true even before the development of the new techniques, for cloning and analysing DNA, that have revolutionized biological research during the past decade. Thousands of millions of dollars are now invested in industrial uses of these techniques, which all depend on discoveries made in the course of academic research on E. coli. Much of the background of knowledge necessary for the cloning and expression of genetically engineered information, as well as the techniques themselves, came from work with this organism.

Over a two-year period 160 episodes of serious infection occurred in 139 infants admitted to a regional neonatal intensive-care unit. Eighty-seven (26%) of very low birth weight (VLBW) neonates and 52 (8%) of infants of birth weight > 1500 g were infected. The majority (84%) had bactcraemia alone. Though the clinical features of infection were not distinctive, in 94% of episodes the peripheral white blood cell or band counts were abnormal. Thirty-three (21%) of the infections occurred in infants under 48 h old and 15 of these followed prolonged rupture of membranes (>48h). All of the infections due to group B streptococci (5), Streptococcus viridans (2) and Haemophilus influenzae (3) occurred in this group. Coagulase-negativc staphylococci (CONS) accounted for 49% of the infections and there was a marked increase in incidence of such infections during the survey. Infections with CONS were not necessarily associated with parenteral nutrition, the presence of intra-arterial catheters or mechanical ventilation but the rise in incidence was coincident with change in skin disinfectant usage and the general use of a third-generation cephalosporin to which the CONS were resistant.

Although VLBW infants with meningitis were more likely to die than those of higher birthweight, the risk for those with bacteriacmia was the same in both groups. Infants with CONS sepsis were less likely to die than those with infections due to Gram-negative bacteria and the time from onset of infection to death was significantly longer for the former.

Caecal samples from 350 Danish bacon pigs were investigated for salmonella using three methods of isolation. (1) Direct inoculation of 1 g of faeces into 10 ml of Muller–Kaufmann medium (MK medium) with addition of 0·3% Teepol 610 and subculture on Brilliant Green lactose sucrose phenol-red agar (BLSF agar) with 0·3% Teepol G10. (2) Pre-enrichment of 5 g of faeces into buffered peptone water with addition of 1% Teepol 610 followed by enrichment of 1 ml in 10 ml MK medium with 1% Teepol 610 and subculture on BLSF agar with 0·3% Teepol. (3) Incubation of 0·1 ml of the pre-enrichment (2) into 10 ml Rappaport-Vassiliadis medium (RV 10 medium) incubated at 43°C, subculture on BLSF agar.

The MK media with and without pre-enrichment yielded higher findings than the RV 10 media. In total, 28 (8%) of the pigs were found positive, representing 11 (7·4%) of a total of 142 herds investigated. Lymph glands were collected at a later date from six of the positive herds. Five of the herds were found positive.

The number of salmonellas in the glands was low, probably less than ten per gram.

Seventy-five strains of Mycobacterium fortuitum were inhibited by 3·0 mg/1 ciprofloxacin but 36 strains of M. chelonei were resistant. The results correlated well with those obtained by the nitratase test. The ciprofloxin sensitivity test is a useful supplement to the tests used to identify these two species.

Vibrio parahaemolyticus was observed to overwinter in sediments and to be present in considerable numbers in sediments and Clithon retropictus (gastropod mollusc) during summer months at a brackish-water area along Hashizu Creek in Japan. The highest level of the organisms was 97·3 × 106 and 2·3 × 107/100 g in sediments and C. retropictus respectively.

Production of Kanagawa haemolysin was detected in approximately 12% and 20% of strains isolated from sediments and C. retropictus respectively at two stations in Hashizu Creek but were not detected at the other three stations. Two haemolysin-producing strains were isolated from water samples but none were isolated from Corbicula japonica (bivalve molluse). These findings suggest that haemolysin producers are preserved principally in sediments and some shellfish in the brackish-water areas with restricted salinity conditions.

A serological survey of free-ranging domestic pigs in the Central and Southern Regions of Malawi, together with laboratory data on confirmed cases of African swine fever (ASF) and data from interviews with pig owners, undertaken over a four-year period from 1981–4, has enabled the ASF enzootic area of Malawi to be identified. The area covers much of the western part of the Central Region and includes Mchinji district and parts of Kasungu, Ntchisi, Dowa and Lilongwe districts. Mortality is substantially less than 100% in outbreaks within the enzootic area but approaches 100% in outbreaks outside this area, as shown by both the serological investigation and the interview data.

Four recently weaned pigs were dosed orally with oxytetracycline. This caused a rapid increase in the incidence of tetracycline resistance (TcR) among Escherichia coli isolates from the faecal flora. The isolates were differentiated further on the basis of O-serogroup, biotype and resistance pattern. There was no evidence that the administration of the antibiotic selected for a few TcR clones, but rather a relatively large number of TcR strains were identified during the dosing period. Using selective isolation media a proportion of these strains were demonstrated in the minority faecal Esch. coli flora before dosing, while the remainder were recognized for the first time after dosing commenced.

The incidence of TcR among Esch. coli isolates also increased after weaning in other pigs which were not dosed with oxytetracycline or any other antibacterial agent. In a proportion of these animals this increase was associated with the dominance of a TcR enteropathogenic serotype (0149:K 91, K 88a, c) in the faecal Esch. coli flora which was probably ingested in small numbers before weaning. The source of other TcR strains was probably the environment in which each pig was placed after weaning.

The efficacy of flocoumafen, a novel anticoagulant rodentide, was evaluated in feeding tests on confined and free-living populations of house mice (Mus musculus L.). In four pen trials, family groups of laboratory-reared wild mice were conditioned to feeding on plain foods and then offered flocoumafen at 0.005% in pinhead oatmeal bait. All 68 mice, comprising juvenile and adult animals, died within 10 days.

Ten field trials were carried out, using the same formulated poison bait, against mice infesting farm buildings. Mean treatment success, estimated from live-capture and mortality data, ranged between 87–1 and 100%.

The performance of flocoumafen is compared with that of difenacoum, bromadiolone and brodifacoum used at the same concentration in oatmeal bait. Flocoumafen gave an equally effective but quicker kill of mice. It is concluded that flocoumafen is a promising new rodenticide for the control of M. musculus.

A review of campylobacter infection in Scotland over five years (1978–82), during which 7808 human isolates were recorded (mean annual isolation rate of 30 per 100000), revealed differences in the epidemiology of the disease between rural and urban populations which were not apparent in the national data. The incidence of infection in the two rural areas studied was greatest in the early months of the year, whereas that in the two urban areas showed a third-quarter predominance. In both urban and rural populations, age-specific infection rates were highest in children less than 5 years old, but this trend was more pronounced in rural than urban populations. Conversely, secondary peaks in age-specific infection rates observed in young adults were more pronounced in the urban than rural populations.

It is postulated that rural children were being infected by campylobacters at an early age by drinking contaminated raw milk which was not normally available to city residents. The lower incidence in adults in the rural populations is interpreted as indicating more widespread immunity, resulting from greater exposure to infection during childhood. The effect of compulsory heat treatment of milk sold in Scotland, introduced in August 1983, is currently being studied.

The results of examinations of stools for Bacillus cereus among three unrelated groups of individuals are presented. The groups consisted of (1) healthy schoolchildren aged 6–11 years in a rural region of South Africa examined during each of the four seasons of the year; (2) 15 healthy volunteers comprising staff of a London microbiology laboratory and their families examined on each of 3 consecutive weeks; (3) 75 unrelated young children, 2 months to 5 years of age, in a second rural region of South Africa examined during a pilot study of 1 week's duration on the aetiology of rural gastroenteritis. The stools of the last group were submitted as being related to present or recent diarrhoea in the respective children.

In group 1, B. cereus isolation rates ranged from 24·3% at the autumn visit to 43% at the summer visit with a significantly higher rate of isolation in the summer than at other seasons of the year (P <0·05). B. cereus was isolated from 40% of group 2 volunteers on week 1, none on week 2 and 20% on week 3. The organism was detected in the 12 positive specimens at levels of approximately 102/g and constituted 2·5–30% of the total aerobic spore-forming bacillus population in the stools. In group 3, B. cereuswas recovered from 18·7% of the stool samples and was isolated consecutively with other pathogens (entcropathogenic Escherichia coli and rotavirus) on only five occasions. In groups 1 and 3, < 5% of the stools had ‘3+ ‘levels of B. cereus(> 10 colonies per direct plate culture).

B. cereus was readily isolated from all of 10 food samples, representative of the typical diet of the group 1 individuals, and was present in substantial numbers (104 to 5·5 × 106/g) in half of them.

The isolation results, supported by serotyping, indicated that carriage of B. cereusin stools is transient and its presence at any one time reflects solely its intake with foods.

Concentrations of air-borne bacteria and particles have been measured in turbulently ventilated operating theatres in full flow, half flow and zero flow conditions. Increased air-borne challenge produced by human activity and by mechanical cleaning procedures is demonstrated: die-away of this contamination is shown to be related to the ventilation rate. Ventilation can be reduced or turned off at night and during weekends, and cleaning can also be carried out, without increased risk of infection if full flow is restored one hour prior to preparation for surgery. Areas surrounding the theatres should remain at positive pressure with regard to the general hospital environment during low or no flow periods. The implementation of such energy-saving policies will substantially reduce theatre running costs without introducing infection hazards.

The ELISA and an immunoblotting technique were used to study F38-type mycoplasmas – an important cause of contagious caprine pleuropneumonia – and a number of related mycoplasma species, subspecies, types or serogroups.

Two-way ELISA cross-reactivity was demonstrated between five mycoplasmas, namely strain F38, Mycoplasma mycoides subsp. mycoides (LC strain), M. equigenilalium, M. primatum and bovine serogroup 7. In addition one-way cross-reactivity was demonstrated between F38 and each of the following mycoplasmas: M. mycoides subsp. mycoides (two SC strains), M. mycoides subsp. capri, and bovine serogroup L. F38 and M. capricolum did not cross-react.

Immunoblot analysis, unlike ELISA, revealed that F38 and M. capricolum were closely related. At least four major protein antigens were shared between F38, M. mycoides subsp. mycoides (SC and LC strains), M. mycoides subsp. capri and bovine serogroup 7. The ELISA cross-reactions (above) shown by M. equigenitalium and M. primatum with each other, with F38 and with other mycoplasmas were not apparent by immunoblotting.

A total of 745 samples of chicken giblets was cultured to determine the relative efficiency of a commercially available Rappaport-Vassiliadis medium (RV-Oxoid). Experiments to determine the optimum inoculation ratio showed that 1:100 was superior to the other ratios tested. Comparison of RV-Oxoid with standard RV and RV-medium prepared using soya peptone (RV-soya) showed that after 24 h RV-soya was significantly better than RV-Oxoid (P < 0·05), although there was no significant difference between standard RV and RV-Oxoid. Furthermore, when the duration of incubation was extended to 48 h there was no significant difference between the three media (P > 0·25).

We conclude that RV-Oxoid is a satisfactory product for the isolation of salmoncllae from poultry, providing that it is inoculated at a ratio of 1:100 and is incubated for 48h. Its use can therefore be recommended to laboratories who wish to use a dehydrated medium.

At least 12 persons contracted clinical, and 4 persons subclinical Brucella melitensis infection during a brucellosis epidemic in the spring and summer of 1983 in Southern Germany, a region which had been free of this disease for the past 20 years. All cases of illness were traced to one infected herd of sheep. The presence of antibodies against B. melitensis was examined in 72 sera of infected patients using the following tests: agglutination, Coomb's test, two complement fixation tests with different antigen preparations (CFT 1 and 2), IgG and IgM enzyme-linked immunosorbent assay (ELISA), and opsonophagocytosis; and the occurrence of cross-reacting antibodies against Yersinia enterocolitca O9 was investigated in the agglutination and complement fixation tests. Sera from 100 blood donors and 112 other people with close contact with sheep were also examined. The results revealed the need to consider an intermediate range in the interpretation of ELISA results – due to elevated values of persons in groups at risk but without clinical signs of illness. In all other tests, however, such persons revealed the same cut-off levels as the general population. Results from all initial sera of infected persons revealed titres of optical densities above the baseline levels determined in the present study, with the exception of the Coomb's and CFT 2 tests. The agglutination test, but not brucella CFT2, revealed complete cross-reactivity between Y. enterocolitica O9 and B. melitensis. ELISA stood out as the only test which is suited to diagnosis of both recent and past infection, since ELISA IgM determination permits conclusions about the time of the onset of illness, and determination of IgG may still yield values above the cut-off level up to G23 days after the onset of illness. In 2 of the 1G infected persons, IgG ELISA was the only test revealing previous infection 424 and 528 days after the onset of illness. A procedural scheme is presented which may help to simplify the diagnosis of brucellosis.

A total of 193 sera were examined for antibody to Mycoplasma pneumoniae by three techniques – complement fixation (CF), haemagglutination (HA) and immunofluorescence (IF), the last method being used to assess IgM, IgG and IgA antibodies. The most reliable single test for diagnosis was HA, and the most useful combination of tests was HA with IF (IgM and IgG). The IgA IF was not found to be diagnostically helpful.

During an average follow-up time of about 2½ years after total hip or knee-joint replacement in 8052 patients, suspected joint infection was recorded in 85 patients whose joints had not been re-operated during that period. The hospital records of 72 of these patients were examined after a further period, averaging about 5 years. Thirty-five of these had suffered continuing major problems with the joint, 18 of which had been revised, and a further 9 joints needed such treatment. Infection was confirmed in 17 of the 35. These numbers are proportionately about three times greater than those observed among a set of matched controls followed-up for a similar period. The evidence from the extended follow-up suggests that the failure rate, unassociated with infection, reached about 5% by 7 years after operation and that late infections, manifested between about 2½ and 7 years after operation, were about as frequent as those confirmed during the first 2½ years.

d-Tartrate dehydrase of Salmonella java is an oxygen-sensitive enzyme active in cultures incubated under the poorly aerated conditions of static culture but not in fully aerated shaken cultures nor on plates incubated aerobically. On plates of d-tartrate minimal agar incubated anaerobically the enzyme or the degradation products of d-tartrate are exported from d-tartrate-positive cells and are available to d-tartrate-negative bacteria. This may give misleading growth results when d-tartrate-positive and d-tartrate-negative strains are tested for growth on the same plate of d-tartrate minimal agar.

The lead-acetate test terminated at 24 h, the 24 h turbidity test and the ability to grow on d-tartrate minimal agar within 48 h differentiated 53 S. paratyphi B strains that were negative in each of the three tests from 76 S. java that were positive in each of the tests. An intermediate group of eight strains utilized d-tartrate in Difco bacto-peptone water to give a positive lead acetate reaction at 2 days, were stimulated to a varying degree by d-tartrate in Oxoid peptone water within the same period of incubation and grew poorly on d-tartrate minimal agar. These latter strains may be deficient in a permease controlling uptake of d-tartrate or export of d-tartrato dehydrase.

Inability to utilize d-tartrate is unlikely to be the single character accountable for the reputed enhanced pathogenicity of S. paraptyphi B when compared with S. java. Indications for the existence of an enzyme, complementary to and mutually exclusive with d-tartrate dehydrase, that has a positive correlation with pathogenicity are discussed.

Two hundred and ninety-nine different strains of Escherichia coli, isolated from 172 patients with diarrhoea and 113 healthy subjects, were examined for enterotoxin, cytotoxin and haemolysin (Hly) production and for mannose-resistant haemagglutination (MRHA) and invasive properties. Three strains proved enterotoxigenic, none enteroinvasive; cytotoxin and Hly production was shown in 25 strains from patients and in 3 from controls. Ten strains produced the cytotoxic necrotizing factor (CNF), 6 released other factors which kill cell cultures. Hly production was shown in 21 strains, 9 of which were also positive for CNF. MRHA was detected in 26% of strains from diarrhoca compared with 14% of strains from healthy people. A strong association between toxin production and MRHA was demonstrated. Serotyping results showed that the strains exhibiting virulence traits mostly belonged to serogroups commonly involved in extra-intestinal infections. The possible role of strains of E. coli showing one or more virulence factors as opportunistic pathogens in diarrhoeal diseases is discussed.