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.

The actiology, epidemiology and clinical presentation of 137 bacteriologically confirmed cases of superficial mycobacterial lymphadenitis identified at the Liverpool Public Health Laboratory between 1969 and 1984 were reviewed. Despite a fall in pulmonary and total extrapulmonary isolates, the annual recovery of mycobacteria from lymph nodes remained relatively constant. Mycobacterium tuberculosis was the cause of infection in 121 patients (88·3%), M. bovis in 6 and the remaining 10 isolates were atypical mycobacteria. In European patients (68·6%) the highest incidence was in the elderly, whereas in non-Europeans (31·4%) the disease almost exclusively occurred in the third and fourth decades. The proportion of isolates from non-Europeans reflected the size of the immigrant population and increased during the period of study.

The virulence of intracranially-inoculated mutant forum of an O18ac:K1:H7 ColV+ stain of Escherichia coli (designated MW) that lacked different combinations of its O and K antigens and CoIV, and of an E. coli K12 strain to which these characters had been transmitted was studied in mice, chickens, ducks and guinea-pigs.

The O18+ K1+Co1V+ form of MW was highly virulent for chickens and mice hut the corresponding form of K12 was only highly virulent for chickens; the O18-K1-ColV- froms of both strains were of low virulence for chickens and mice. K1 was more important than O18 or ColV in determining virulence for both animal species, Ducks and guinca-pigs resembled chickens, not mice, in their response to infection with the O18+K1+ColV+ from of K12.

Pathogenesis studies revealed than the virulence of the forms of MW and K12 was associated with their ability to proliferate in the central nervous system; only low numbers of organisms were found in the blood and spleen of inoculated animals.

The O18+K1+ColV+ form of K12 multiplied in mouse brian and in mouse blood in eitro; its multiplication in chicken blood was partinlly inhibited. Agglutinins to this and other forms of K12 were found in chicken serum but not in mouse serum. Large doses of mouse serum given to chickens and large doeses of checken serum given to mice did not alter the manner in which these animals responded to K12 O18+K1+ColV+ infection. Vaceination protected chickens and mice against lethal intraeranial infection with the O18+K1+ColV+ forms of K12 or MW; it produicted a much stronger immunity in mice against intrapertoneal challenge than against intraeranial challeage

A dispersal chamber (body box) technique has been used to compare bacterial dispersal from the skin of subjects carrying out a stepping test under controlled conditions while wearing four differing garment systems namely:

(a) basic underwear, cotton ‘blues’ (standard pyjama style jacket and trousers for men or dress for women), ankle socks, boots for men and shoes for women, mask and theatre hat; (b) the basic set covered with a cotton gown; (c) the basic set covered by a gown with a front made from GORE-TEX fabric in which an expanded polytetrafluoroethylene membrane is sandwiched between layers of woven or knitted polyester; (d) the basic set covered with a fully enclosed suit of the same fabric.

A slit sampler was used to measure the number of bacteria liberated in a downward current of air. Six subjects (three female and three male) were studied. Males liberated more bacteria. Covering the ‘blues’ with a cotton gown increased the bacterial count; a gown of the new material reduced the increase by 50%, and the suit cut the dispersal to virtually zero.

Preliminary work suggests that GORE-TEX garments survive laundering better than cotton, and may be cost-effective, but are not yet as comfortable. Research is presently in progress to improve this aspect.

An outbreak of streptococcal throat infection which took place in a preparatory school for boys (some of whom were choristers) over three terms from November 1983 to June 1984 is described. Typing of the organism revealed that four successive outbreaks, each due to a different type, had occurred. Thirty-nine per cent of the boys were affected, the incidence of infection being higher among boarders than day boys. Infection seemed to spread via the forms, dormitories and choir. Recurrent attacks occurred in 32% of infected boys. The complication rate was 8%. Treatment with penicillin was always effective but did not prevent reinfection. Suggestions for the management of an outbreak of sore throat in a school are given.

Foods from outbreaks of food poisoning were examined for the presence of staphylococcal enterotoxin A (SEA) by a sandwich ELISA using microtitre trays as the solid phase and SEA antibodies raised in sheep.

The presence of SEA was confirmed by neutralization tests. The toxin was detected in 12 of 15 foods from separate outbreaks of staphylococcal food poisoning; all 15 foods contained a strain of Staphylococcus aureus which produced SEA. For most foods a simple extraction procedure without a concentration step was sufficient to detect the toxin. The method was semi-quantitative and recoveries of SEA added to control foods varied from 30 to 80%. The foods from outbreaks contained between 1 and 10 μg of SEA/100 g. SEA was not found in foods from 21 outbreaks in which an SEA-producing strain of Staph. aureus was not isolated.

In Alice Springs and its vicinity, a single nasal swab was collected from 282 Australian aborigines in May 1981 to determine nasal carriage rates of pneumococci. Each swab was inoculated on blood agar and on gentamicin blood agar. The carriage rates were 89% in children, 39% in adolescents and 34% in adults. In all, 27 serotypes of pneumococci were met with and 15 (4%) of subjects yielded two or more serotypes. In children, types 23, 19, 6, 22 and 6 were predominant (in that order), whereas type 3 was commonest in older subjects. Approximately 25% children and 5% adults yielded drug-insensitive pneumococci. Resistance to benzylpenicillin, tetracycline and co-trimoxazole was met with, resistant pneumococci showed five resistance patterns and belonged to nine serotypes, predominantly types 19 and 23. All isolates were sensitive to chloramphenicol, erythromycin, lincomycin and rifampicin. The carriage rate of drug-insensitive pneumococci was 100-fold higher amongst children sampled than in non-aboriginal children in Australia.

As an estimate of their virulence, the ability of ovine, bovine, canine, feline and simian ureaplasma strains to cause mastitis in the ovine mammary gland was investigated. Five ovine ureaplasmas produced a clinical mastitis. Broth cultures of seven bovine ureaplasmas were unable to infect the ovine gland, but two of these strains plus one other were able to do so following passage through the bovine udder. One of two canine strains and a feline strain both caused mastitis, but the simian strain persisted at low titre for only 5 days post-inoculation in one of the two ewes tested.

A total of 574 samples, of seven different types, were examined for the presence of salmonellas. All the specimens were pre-enriched in buffered peptone water and enriched in Rappaport–Vassiliadis medium (RV medium). In one trial 0·1 ml of pre-enrichment culture of 497 samples (79 chicken carcasses, 228 specimens of minced meat, 100 pork sausages, 19 samples of dried powdered chicken meat, 11 specimens of faeces of healthy pigs and 60 samples of sewage polluted natural sea water) was seeded to 10 ml as well as to 100 ml of RV medium. With the first inoculum (ratio 0·1:10), 111 samples were found to contain salmonellas, while with the second inoculum (ratio 0·1:100), only 102 positive samples were detected. This difference is marginally significant (P < 0·05). In another trial, 0·1 ml, 0·2 ml and 0·5 ml of pre-enrichment culture of 162 specimens (71 chicken carcasses, 40 samples of sewage polluted sea water and 51 samples of sewage polluted river water) were in turn introduced to 10 ml of RV medium. With the 0·1 ml inoculum 93 positive samples were detected, while with the 0·2 and 0·5 ml inocula 93 and 88 positive samples were found. The differences are not statistically significant. In these trials the growth of competing organisms was minimal with ratios of inocula 0·1:10 or 0·1:100.

Strains of Staphylococcus aureus isolated from shrimp were examined for phage pattern and enterotoxin production; 63% of the strains isolated from North Sea shrimp were typable with the International and additional set of phages, as were 38% of the strains isolated from South-East Asian shrimp. Staphylococcal enterotoxin(s) (SE) were produced by 48% and 35% of strains isolated from North Sea and South-East Asian shrimp respectively. Growth and enterotoxin production by S. aureus in shrimp was examined in storage experiments at 22 °C. S. aureus increased by 1–2 log units in 24 h when the organism was only a minor part of the total microflora of shrimp. When S. aureus was an equivalent part of the total flora its numbers increased by 3–4 log units in 24 h. Enterotoxins A and B became detectable when the number of S. aureus exceeded 107 per g in aseptically peeled shrimp. Results indicate that S. aureus is able to produce enterotoxin in shrimp, but its production depends upon a number of factors, including the relationship between S. aureus and competitive micro-organisms. It is concluded that the presence of S. aureus on commercially produced shrimp represents a potential hazard to health.

A swabbing technique was compared with an excision and maceration technique for bacteriological sampling of pig carcass skin surfaces. Total viable counts at 37 °C obtained by swabbing were 46% of those obtained by maceration. At 21 °C, swabbing gave total viable counts which were 54% of the counts obtained from excision samples. Escherichia coli counts showed wide variation with both sampling methods. Neither method was more efficient than the other in recovering E. coli, although excision sampling gave generally higher counts. Both methods were equally effective at recovering salmonellac from carcass surfaces. There was no significant difference between the methods in recovering particular Salmonella serotypes.

An outbreak of bluetongue in sheep started in the Menderes valley, Aydin Province, Western Turkey, in October 1977. The severity of the disease indicated that it had not been there before but had been introduced into the area. Anatysis showed that, while it was possible for the virus to have been brought into the area by movement of infected animals, there was also a period of south-easterly winds which could have carried infected midges from Cyprus, where bluetongue was present. During the night of 14–15 October 1977, south-easterly winds could have brought midges infected with bluetongue virus for the 15 h flight at a height possibly of 500 m and at temperatures of about 20 °C. A depression moving north-eastwards accompanied by rain may have affected the landing of midges in the Menderes valley on the morning of 15 October.

An outbreak of arthrogryposis–hydranencephaly in newly born calves occurred in March–May 1980, also in the Menderes valley, Aydin Province. The severity of the outbreak indicated that Akabane virus had not been in the area before but had been introduced in September–November the previous year. While infected animals could have brought the virus into the area, analysis based on the probable time of infection of pregnant dams showed that easterly winds at the end of September or beginning of October 1979 could have brought insects infected with Akabane virus into the Menderes valley from eastern Turkey or northern Syria.

These analyses illustrate the use of meteorological data to backtrack to possible sources and to identify the time of infection.

Laboratory studies were performed on 128 children clinically diagnosed as measles when seen at the Infectious Diseases Hospital, Kenyatta National Hospital (IDH), Nairobi (86 cases) and the Rural Health Training Centre, Maragua, Central Province (42 cases) between 9 July and 31 August 1984. A concurrent measles infection was confirmed in 95% of the children seen at IDH and in 85% of those seen at Maragua, with similar proportions of confirmations in children who had, and who had not, received measles vaccine. No differences in the number of sero-conversions nor in the absolute levels of acute or convalescent HI antibody titres could be detected between vaccinated and unvaccinated children. Analysis of the cases seen at Maragua indicates that about two thirds of the children who had received vaccine were protected. A pilot study of vaccinating children at 8 months and again at 12–13 months is suggested in an attempt to eradicate measles.

Trimethoprim resistance was seen in 14·8% of 500 strains of salmonella, 43·1% of 153 strains ofshigella and 59% of 27 strains of Escherichia coli isolated from stools of patients with diarrhoea. Strains with a high level of trimethoprim resistance (MIC of ≥ 512 μg) were subjected to conjugal transfer. Trimethoprim resistance was plasmid-mediated in all of 42 strains of shigella and 12 strains of E. coli examined. However, 2 of the 47 strains of salmonella could not transfer their trimethoprim resistance either directly or by mobilization with the transfer factors X and Δ both at 37 and 25 °C overnight incubation.

We studied the effect of oral selective antibiotic decontamination (SD) on the faecal endotoxin content and microflora in individual C57BL mice. Suppression of the coliform count was associated with an initial rise in faecal endotoxin concentration from 0·1 to 3·1 mg/g wet faeces during the first week of SD, which fell to 0·04 mg/g during the second week of treatment. Cessation of SD resulted in an immediate sharp increase in coliform count followed by its decline and gradual recovery to pro-treatment counts. Faecal endotoxin levels followed a parallel course. SD did not effect significantly the counts of lactobacilli, baeteroides and enterococci.

It appears that the coliform population is responsible for the overall level of faecal endotoxin, and that during the initial period of SD endotoxin levels are elevated, an effect which may be mediated by antibiotic-enhanced release of endotoxin.

Influenza A antibodies in serum samples obtained in 1980 from two Indian populations in Central Brazil were compared. The Kren-Akorore, who were first contacted in 1973 and two years later transferred to the Xingu Indian Park (PIX), were compared with Indians from other tribes already living in the PIX before 1975. An analysis was made of the prevalence and distribution of antibodies against the influenza A viruses which have circulated in the civilized world since 1918. Antibodies to the early influenza A viruses were absent in both Indian populations, but A/Hong Kong/1/68 (H3N2) virus apparently circulated in the PIX. No antibody to influenza A/Bangkok/I/79 or to A/Brazil/11/78 (H1N1) was found in any of the sera, whereas antibodies to these viruses were commonly found in urban populations in Brazil. The evidence from influenza antibodies agrees with the information that the Kren-Akorore Indians had been living in complete isolation until 1973, when they were first contacted.

Studies were made on 33 immunocompetent patients with cryptosporidiosis (31 of them children) to determine how long oocyst shedding continued after the cessation of diarrhoea. The majority (20/33) ceased to shed oocysts in the week following the cessation of diarrhoea. However 5 patients (15%) continued to shed oocysts for 2 weeks or more, and 1 patient was still shedding oocysts when lost to follow-up 3 weeks after the diarrhoea ceased.

There was considerable variation among patients, and some eliminated oocysts more efficiently and quickly than others. The sucrose flotation technique was more useful than direct smear for detecting the low numbers present at the end of the shedding period. Limited information suggested that a carrier state or relapse is probably rare.

One contact plate and two homogenization methods have been compared for efficiency in assessing the bacterial contamination of fabrics with high or low, natural or artificial contamination. The contact plate method resulted in considerably lower counts than any of the homogenization methods, which closely resembled one another. One of these, utilizing a Stomacher 400®, was found to be more practical, and is therefore recommended for counting bacteria on fabrics.

There is recent evidence of bluetongue (BT) and epizootic haemorrhagic disease (EHD) virus infection of cattle in the American tropics, including BT group reactive antibody in Colombian cattle. These observations prompted a study to determine serologically the specific BT and EHD virus types present, and time of infection and to collect Culicoides spp. as potential vectors. A prospective study of BT and EHD virus infection was done on two farms in the Colombian department of Antioquia. Sequential sampling of young cattle indicated acquisition of neutralizing antibody to BT virus serotypes 12, 14 and 17, and EHD virus serotypes 1 and 2. Insect captures showed a high association of Culicoides insignis with infected cattle.