The genetics of gentamicin resistance in Staphylococcus aureus strains isolated during an outbreak of infection in a dermatology department have been studied. The predominant strain of S. aureus did not appear to possess a plasmid mediating gentamicin resistance though one isolate yielded a plasmid coding for penicillin and gentamicin. Three distinct plasmids were isolated from other phage types of S. aureus which appeared towards the end of the epidemic. There appeared to be a stepwise loss of gentamicin resistance in the predominant strain.

An estimate of the benefits which would result from a ban on the sale of non-pasteurized milk in Scotland has been assessed by costing a recent outbreak of milk-borne salmonellosis in the Grampian Region.

The cost of such a ban would not exceed the benefits under any but the most severe assumptions about the values attached to intangible benefits

A short study of salmonella isolation from reptile faeces is described. The samples came from the reptile house at the Bristol Zoological Gardens. The wide range of salmonella serotypes present in the material, including representatives of all four subgenera, is noted. The important factors in the technique of isolation are discussed. These are choice of inoculum, enrichment medium, and plating Medium, useof multiple subculture and serological isolation. If the number of samples available is scanty, an extended technique will probably yield more information than a simple method.

A total of 495 calves in 16 batches were examined (117 calves in 4 batches in 1979 and 378 in 12 batches in 1982). They were purchased in markets, transported by road to a farm in Somerset and reared ona milk substitute diet for a period of up to five weeks. Salmonella typhimurium phage type DT 193 was endemic in 1979 and phage type DT 204c in 1982. The mortality rates in the two years were 9·4% and 1·9% respectively. The causes of death were not investigated although the majority were probably due to salmonellosis.

The rate of isolation of S. typhimurium from the rectal faeces of calves in all groups was either zero or relatively low on arrival. It rose to a peak (which was higher in 1979) in the second or third weeks before declining to low levels by the end of the fourth week of residence on the farm.

Data from 162 calves, examined twice weekly for four weeks in 1982, indicated that the distributionof infected calves, based on the number of times that S. typhimurium was isolated from each, was not random. The calves could be assigned to two main categories; those from which the organism was never isolated and those from which it was isolated at least twice. This suggested that salmonella infected calves actively excreted the organism.

The association between salmonella excretion and medication of sick animals with antibacterial drugs was strongest during the second week. Over the four-week period nearly 40% of the calves found to be excreting S. typhimurium were not treated, indicating a high incidence of subclinical infection.

Salmonella excretion by the calves followed a regular pattern and infection was self-limiting within five weeks. The peak in the salmonella excretion rate and the mortality rate were higher in 1979 when phage type DT 193 was the endemic strain. However, in 1982 the calves received 100 p.p.m. furazolidone in their milk ration during the first week of their stay on the farm, and this may have contributed to the differences noted between the two years.

The numbers of salmonella serotypes in raw sewage, sewage sludge and final effluent at a sewage treatment works were determined. Resting gulls which had previously been feeding on the sewage were disturbed and individual faecal samples tested for the presence of salmonellae. The serotypes were compared with those in the sewage. Six serotypes were isolated from the sewage, Salmonella Stanley being found in all types of sample. Eleven of the twenty gull faeces samples were positive for salmonellae, a carriage rate of 55%. Seven serotypes were found, S. stanley being most frequent. Three serotypes were found in both sewage and gull faeces.

The relative efficiency of three selective enrichment broths (Muller-Kauffmann tetrathionate, Rappaport's and selenite F) was investigated for the isolation of salmonellae from seagull cloacal swabs. Pre-enrichment in buffered peptone water was employed throughout the study, which involved the examination of 560 gulls, sixty (10·7%) of which were found to be carrying salmonellae. Rappaport's broth as modified by Vassiliadis for incubation at 43°C (Vassiliadis et al. 1976) yielded the highest number of positive swabs (57) and the widest range of serotypes. It was significantly more efficient that either selenite F or tetrathionate broth, although the results obtained with Rappaport's broth incubated at 37 and 43°C did not differ significantly (P > 0·5). Eleven serotypes were isolated during, the study, the most prevalent being Salmonella virchow.

At a pig-fattening farm in the south-western Veluwe which was infected with salmonellas it was sought to achieve salmonella-free fattening in a specially adapted piggery. The test piggery was thoroughly cleaned and disinfected and measures were taken to exclude birds, insects and rodents. An attempt was also made to obtain salmonella-free piglets. Clean clothing, special footwear and disinfectants were used when entering the piggery.

During the experiment an infection was detected in the test piggery caused by the same salmonella serotypes as had only been found immediately before the test at the breeding farm. Other salmonella serotypes occurring at the fattening farm did not find their way into the test piggery, and therefore it can be concluded that after the pigs had been brought in all the hygienic barriers functioned adequately. The test showed that the hygienic measures taken had a beneficial effect on growth performance, even though salmonellas were not entirely excluded.

After fattening the pigs were slaughtered in two groups. The first group was slaughtered in the usual way, but with the second group extra care was taken with the individual singeing of the carcasses and the careful removal of the intestines. Tests on the carcasses showed that 46% of the pigs in the first group were contaminated with salmonellas as against only 7% in the second. From this it can be concluded that slaughter need not lead to further contamination by salmonellas present in the intestines; indeed, carefully carrying out the slaughter process can even reduce the contamination of the surface of pig carcasses by salmonellas.

Studies of group A, M type 49 streptococci from England, Trinidad and Alaska indicate that isolates of this serotype often differ with respect to phage subtype from one geographical areato another, but are generally homogeneous in one place at one time. The findings support the conclusion that acute glomerulonephritis can be associated with a variety of phage subtypes of M type 49 streptococci.

In outbreaks of skin sepsis without nephritis in England, the phage subtypes of M type 49 streptococci isolated from skin lesions of meat handlers were the same as those recovered from skin lesions of non-meat handlers in the same community.

The findings on the Trinidad isolates suggest that M type 49 streptococci of one phage subtype may persist in a population for 9 years and may result in a second outbreak of acute glomerulonephritis.

In an Alaska Eskimo population in whom acute glomerulonephritis was occurring, most of the M type 49 isolates available for testing were of a single phage subtype. Equally prevalent in this population were group A streptococci that exhibited the same T antigen as the type 49 isolates but differed in their serum opacity reaction and phage subtype. This apparently related strain was not typable with available M antisera but showed functional evidence of M protein and is probably a new M type.

A total of 495 diarrhoea and non-diarrhoea patients whose ages ranged between 5 and 39 years were examined for the presence of Campylobacter jejuni, Salmonella and Shigella species. About 12% of the specimens from diarrhoea patients were positive for Campylobacter jejuni compared with 6% and 10% for Salmonella and Shigella species. In contrast 2%, 0% and 1% of the samples from non-diarrhoea patients were positive for Campylobacter jejuni, Salmonella and Shigella species respectively.

Most (62%) of the Campylobacter jejunifrom diarrhoea patients were isolated from children under the age of 10 years. This compared with 26 % and 37 % for Salmonella and Shigella species in this age group. The frequency of isolation of Campylobacter jejuni in diarrhoea patients was highest during the dry months of the year. This study demonstrates the importance of Carnpylobacter jejuni as a major bacterial cause of diarrhoea in this part of the world.

Experiments have been performed to simulate accidents which may occur during large-scale production of micro-organisms. Four types of accident, which were considered to be the most likely to result in the greatest hazard to health, were simulated using a bacterial model. The accidents were all concerned with faults occurring in the operation of the microbial fermenter. Gross contamination of surfaces occurred in all experiments, but only three types of accident produced a measurable aerosol.

The resistance of spores of B. subtilis var. niger produced in liquid synthetic medium and exposed to ethylene oxide on a nylon surface, has been shown to be almost identical to that for spores produced on a traditional solidified complex medium with exposure to the sterilant on aluminium foil. The use of short lengths of nylon tube as carriers allowed easy production and handling, with self-protection of the spore-bearing surface. Addition of a dye provided visual evidence of inoculation without affecting resistance to ethylene oxide. Such a monitor is suitable for use as a standardized biological challenge in routine ethylene oxide sterilization cycles.

In April 1982, Katsina, in Northern Nigeria, was affected by an outbreak of gastroenteritis associated with Vibrio cholerae serotype ‘Ogawa’ and 662 patients were admitted to the Katsina General Hospital during a 16-week period. The outbreak affected all ages and both sexes and all parts of the town and its immediate surroundings except the Government Residential Area (GRA). The overall case fatality rate was 7·7%. Male specific case fatality and female specific case fatality rates were 9·7 and 6·2% respectively. ‘Adults’ and those in the 11–20 and 21–30 age groups accounted for most of the cases. The epidemic curve was of a propagated and protracted nature. About 51·7% of all the patients spent between 2 and 5 days in the hospital. A similar pattern was observed for all age groups regardless of sex. Cholera vibrio ‘Ogawa’, Shigella spp., Salmonella spp., Proteus spp. and Escherichia coli were isolated from 16 patients. All well-water samples obtained from the compounds of the cases were contaminated with MPN/100 ml index ranging from 540 to greater than 2400. All samples were positive for faecal coliforms. Salmonella spp., Shigella spp., Proteus spp. and non-0, group 1 (non-0 1) V. cholerae were isolated. Water sellers probably facilitated the spread of the outbreak.

Monoclonal antibodies to the serum parovirus-like virus (SPLV) were prepared by the hybridoma technique. They provided an antibody reagent which was used to develop solid phase antibody-capture assays for anti-SPLV IgM and IgG and for SPLV antigen. These assays were more sensitive than those based on human convalescent antibody as a reagent, and were more economical in the use of SPLV antigen. Their use enabled the serological responses to SPLV to be studied more fully and their sensitivity revealed the extent of SPLV infection.

SPLV antigen was detected in four patients by both counter-immuno electrophoresis (CIE) and radioimmunoassay (RIA) and in two others by RIA alone. Parvovirus particles were seen in all six by electron microscopy. The anti-SPLV IgM response was measured in patients infected by SPLV. It was strong 5–18 days after the onset of illness, then declined and was only detectable in trace amounts after 6 months. Anti-SPLV IgG was also formed early, and persisted for at least 6 months. In a survey of 310 blood donors anti-SPLV was detected in 134 (43%) by CIE, but in 190 (61 %) by IgG antibody capture RIA.

Eight hundred and seventy-seven sera from 360 adults aged 18–50 who were under permanent observation from October 1980 to March 1981 have been studied by haemagglutination-inhibition (HI) and erythrocyte elution-inhibition (EI) tests – a simplified method of antineuraminidase antibody titration. It was demonstrated in some subjects infected with influenza A H1N1 and H3N2 viruses that the antibody rise was to one of the surface antigens only – haemagglutinin or neuraminidase. These subjects made up 5·2–25·8% of all examinees. The protective effect of antibodies to neuraminidase was similar to that of antihaemagglutinins. Interaction of both types of antibodies was observed in protection against the disease. Data have been obtained on the influence of antineuraminidase antibodies in decreasing the severity of natural infection with influenza A.

A study of heterologous immunologic responses to haemagglutinin and neuraminidase among persons immunized with live influenza A H1N1 and H3N2 vaccines and among children naturally infected with influenza A H3N2 demonstrated the presence of immunologic memory for antineuraminidase antibody synthesis. Thus, the suggestion of a common antigenic structure for neuraminidase Nl and N2 is made.

A high incidence of gastroenteritis in both islanders and tourists has been recorded in recent years on Norfolk Island – a popular tourist resort for Australians and New Zealanders. No bacterial cause has been found. However, electron microscopic examination of 28 faecal specimens revealed viruses associated with gastroenteritis in 21 (75%). No viruses were isolated in cell cultures. Bore water is used for drinking purposes on the island and 32 samples from 15 bores were examined for viruses by electron microscopy and culture as well as for bacterial contamination. Seven polioviruses (all type 1 vaccine strain) and adenoviruses 1 and 5 were isolated in cell cultures. In addition one rotavirus, one adenovirus and two small round viruses were detected by electron microscopy. Six of 21 samples tested showed unacceptably high levels of bacteria for drinking water. The deep ground water has apparently become contaminated with sewage effluent and is almost certainly the main cause of the high level of gastroenteritis on the island.

A radial haemolysis test designed to detect antibody specifically directed against the neuraminidase is described and compared with currently available techniques for the routine diagnosis of infection with influenza viruses.

Paired sera were available from two outbreaks of influenza A, one with the N1N1 subtype and the other with the H3N2 subtype. This technique confirmed diagnosis in 92% of cases diagnosed by other laboratory methods.

The sensitivities of haemagglutination-inhibition (HI) and single radial haemolysis (SRH) techiques in detecting antibodies against influenza A/Bangkok/1/79, A/Brazil/11/78, B/Singapore/222/79, B/Hong Kong/5/72 strains, in human sera were compared. For antibodies to influenza B viruses the HI tests employing ether-treated antigens were also evaluated. The SRH technique appears to be more sensitive for detecting protective titres of antibodies against influenza B strains and influenza A/Brazil/11/78.

An outbreak of hepatitis A occurred among the members of the Japan Overseas Corporation Volunteers (JOCV) stationed in the Philippines. Seven out of 10 youths who ate, but none of five youths who did not eat raw oysters developed hepatitis. All these seven cases were positive for hepatitis A antibody (anti-HAV) and six of them were also positive for anti-HAV IgM (immunoglobulin M) 111 days after the infection.