A test is described for assessing the effect of hypochlorites in reducing the bacterial load on soiled napkins during storage, between removal from the infant and the laundering.

Groups of student volunteers were immunized with one of five different inactivated influenza virus vaccines. The concentration of virus in the various vaccines differed by both the international unitage test and by the concentration of haemagglutinin, as measured by the single radial diffusion test; the results of the two methods of standardization showed no correlation. The serum HI response to immunization was variable; volunteers given A/England/72 showed a 16·6-fold increase in homologous serum antibody titre whilst volunteers given A/Hong Kong/68 vaccine showed a 4·2-fold increase. The variable response of volunteers to immunization could not be explained by the varied concentration of virus in the vaccines, as measured by either test, the titres of serum HI antibody present before immunization, or a combination of these two factors.

The ability to infect volunteers with WRL 105 virus 4 weeks after immunization with heterologous, inactivated virus vaccine was directly related to the degree of cross-reactivity between the haemagglutinins of this vaccine virus and WRL 105 virus. Thus, the greatest number of infections by the challenge virus were seen in volunteers given A/Hong Kong/68 vaccine, less were observed in volunteers given A/England/72 vaccine, and least were found in groups given A/Port Chalmers/73 or A/Scotland/74 vaccine. However, compared with the incidence of infection in volunteers given B/Hong Kong/73 vaccine, all the heterologous influenza A vaccine gave some immunity to challenge infection.

Milk chocolate mass containing salmonellas was prepared by mixing artificially contaminated milk powder with the other ingredients at a temperature of about 40 °C. From this mass bars were made. Two series were prepared, with S. eastbourne and S. typhimurium respectively. The number of surviving salmonellas was counted after various periods of storage, up to 19 months. S. eastbourne was reduced in numbers during 19 months from an initial count of ca. 3 × 104 to ca. 3 × 102 per 100 g of chocolate. S. typhimurium died off more rapidly, and was not detectable in about 55 g after 15 months, in spite of an initial count of ca. 105 per 100g.

In these experiments the salmonellas in the milk powder had had to survive the spraying procedure and the adverse conditions in the dried powder. This may be the reason why S. eastbourne showed a distinctly better survival on storage than the same serotype showed in previous experiments in which the organism was added as a broth culture to the chocolate mix. With S. typhimurium, however, such a difference was hardly detectable.

Possible explanations of these results are discussed.

The faecal survival of Salmonella typhimurium orally administered to restrained American cockroaches maintained on an antibiotic diet was investigated. Significant reductions in median numbers of total aerobic faecal microorganisms were noted in insects fed antibiotics daily, and when Salmonella was introduced to this modified micro-environment, it persisted for 44 days in all specimens. Multiplication of the pathogen was also observed in these insects, with numbers often exceeding 103 times that of the initial input. This differs significantly from our previous results showing that the pathogen is unable to multiply in conventional cockroaches. Attempts to restore the normal flora by feeding a faecal suspension from untreated cockroaches resulted in a decrease in numbers of Salmonella excreted, but did not result in their elimination. Carcasses of infected cockroaches retained viable Salmonella for at least 60 days post mortem, or 104 days after the infective meal.

The fluorescent antibody technique was used for the identification of specific cytomegalovirus IgM in the sera of twenty-four of 1065 unmarried pregnant women. Seventeen of them were followed to term and five infected infants were identified. Two other infants had CMV IgM in neonatal serum samples but virus excretion was not demonstrated. The congenital infection rate in this study was 5·3 per 1000 births by virus excretion and 7·9 per 1000 if cases with specific IgM are included; from previous studies a rate of 8·8 per 1000 was expected. The reasons for the lack of relationship between specific IgM in the mothers' serum and infected babies is discussed.

The use of a single-radial-haemolysis technique for the detection of antibody to rubella virus is described. The single-radial-haemolysis test was compared with the standard HI methods for the detection of antibody to rubella virus. A close correlation between the two methods was observed in a survey of over two thousand serum samples and the study indicated that single-radial-haemolysis was highly satisfactory as an assay method for IgG antibodies to rubella virus. It was found that the immuno-globulins active in SRH tests sedimented in the 7S range in sucrose rate gradients and were presumably immunoglobulins of the IgG class, but 19S iinmunoglobulins did not produce haemolysis.

Three hundred and fifty-seven sera selected at random from hospital patients of all ages were examined for rotavirus antibodies using indirect immunofluorescence (FA) and complement fixation tests (CFT). Three hundred and fourteen of these were also tested for neutralizing antibodies to human rotavirus. Sera from patients admitted with a diagnosis of acute gastroenteritis were excluded from this survey.

FA antibodies were found in newborn infants but fell to undetectable titres at 3 months. The highest titres were found in children between the ages of one and three years. In older age groups, the modal titre fell gradually with increasing age until, in sera from those above 70 years of age, FA antibodies were almost undetectable. The same pattern was observed with neutralizing antibodies. A high modal titre of CF antibodies was only found in sera from those aged one to three years.

Samples of frozen precooked rock lobster meat from five South Australian fish-processing plants situated in the West Coast and south-east regions were tested over a period of six months during the 1974/5 lobster fishing season. The most probable number (MPN) of E. coli and coliforms, Staphylococcus aureus and Salmonella, as well as total plate count (TPC) were determined in 480 samples. Monthly geometric mean TPC ranged from 1600/g to 25,000/g. The highest geometric mean of the MPN of coliforms and E. coli were 4·9/g and 1·8/g respectively. The highest geometric mean number of staphylococci was 18·6/g. Salmonella was not detected in the 480 units tested. Only 0·4% of the samples had TPC exceeding 100,000/g. Coliforms and E. coli were not present in 76·1% and 92·7% respectively of the samples tested. Staphylococcus aureus was not detected in 67·7% of the samples. The numbers of organisms in 82% of the samples fall within the microbiological standards proposed by the National Health and Medical Research Council of Australia for frozen precooked foods. The results of this study demonstrate the microbial quality of precooked lobster meat attainable when good manufacturing practices are used.

Campylobacter fetus was isolated from five recent cases of human vibriosis, of which two were adults and three were children. One adult presented with pericarditis and the other with recurrent pyrexia. Campylobacter fetus subsp. intestinalis which resembled cattle strains serologically, was isolated under CO2 or anaerobic conditions from blood cultures of these patients. Two of the three children had kwashiorkor and the third was only 8 days old. Isolates identified as Campylobacter fetus subsp. jejuni were cultured from blood of these patients, two of whom had diarrhoea. Three patients succumbed, despite adequate antibiotic therapy. The epidemiology of the disease is discussed and it is suggested that infection may have been from the patients' own flora.

A metabolic inhibition test based upon phosphatase production is described. This is of value for those Mycoplasma species which produce phosphatase but which cannot be examined by the previously published metabolic inhibition techniques.

The ability of certain Escherichia coli strains to produce enterotoxin is determined by transmissible plasmids. It is therefore possible that any E. coli strain might be able to acquire such a plasmid and that the correlation between enterotoxigenicity and serotype might be random. However, recent studies show that the enterotoxigenic strains so far described belong to a restricted range of serotypes. Enterotoxigenic strains of E. coli O6.H16 and E. coli O148.H28 have been associated with outbreaks of diarrhoea in several countries, therefore strains of E. coli belonging to these serotypes were selected for further study.

Twenty-three strains of E. coli O6.H16 and 14 strains of E. coli O148.H28 were examined; 20 strains of E. coli O6.H16 and all 14 strains of E. coli 0148.H28 were enterotoxigenic but strains of E. coli O6 with flagellar antigens other than H16 and strains of E. coli O148 with flagellar antigens other than H28 were not enterotoxigenic. The examination of single colony subcultures derived from the E. coli O6.H16 strains showed that in some strains loss of enterotoxigenicity had occurred in a proportion of colonies.

The European rabbit flea Spilopsyllus cuniculi (Dale) was introduced into Australia to act as a vector of myxoma virus. It was first released in the semi-arid Mallee region of Victoria in 1970 where epizootics caused by field strains of myxoma virus occur each summer. Introductions of the readily identified Lausanne strain were made annually following the release of the flea. The introductions were successful and the strain persisted for up to 16 weeks despite competition from field strains.

The Lausanne strain is more readily spread by fleas than the Glenfield strain which has been widely used in rabbit control. The ability of the Lausanne strain to persist and its effective transmission compared with the Glenfield strain may be due in part to the more florid symptoms of the disease.

Wild rabbits (Oryctolagus cuniculus) from one study area in England have been used over a period of 11 years to investigate the possible appearance of innate resistance to myxomatosis. Rabbits of 4–6 weeks old were captured alive, retained in the laboratory until at least 4 months old, and then infected with a type of myxoma virus which kills 90–95% of laboratory rabbits. Observations were made of symptoms, mortality rate and survival times.

In the first 4 years of the study (1966–9), mortality rates were not significantly different from those of laboratory rabbits, although survival times of wild rabbits were appreciably longer. In 1970, the mortality rate amongst wild rabbits was 59%, in 1974 it was 17%, and in 1976 it was 20%, thus showing that a considerable degree of inherited resistance to myxomatosis has developed.

The types of myxoma virus most commonly isolated from wild rabbits in Great Britain in recent years have been those which cause 70–95% mortality in laboratory rabbits. Therefore, if the degree of innate resistance demonstrated is widespread in Great Britain, there are serious implications regarding the size of the rabbit population, because myxomatosis has been an important factor in holding rabbit numbers at a relatively low level.

Skin scales may be attracted onto the surface of administration set connector needles before insertion into infusion containers. Viable microorganisms associated with skin scales may therefore gain access to the infusion by this route. A technique is described for creating an environment of airborne skin scales. This environment is used to examine the attraction of skin scales onto the surface of administration set connector needles and three other materials. After exposure, skin scales are found adhering to the surface of each material examined. The attraction of skin scales onto administration set connector needles is dependent on the time of exposure to the environment. Results suggest that intravenous infusions can be contaminated by this route when the infusion and administration set is assembled.

Strains of Salmonella typhimurium of predominantly Middle Eastern origin, but distributed from England to India, were found to carry at least three types of resistance plasmid. The most important was initially identified as an FI plasmid by compatibility tests, but differs from the F factor on the one hand and the FI factors R162 and CoIV on the other. The three groups of FI plasmids can be distinguished by their compatibility reactions with the MP10 plasmid of S. typhimurium (Smith, Humphreys, Grindley, Grindley & Anderson, 1973) and group H1 factors: the F factor is unilaterally incompatible with group H1 (Smith, Grindley, Humphreys & Anderson, 1973; Anderson, 1975b); the FI factors are compatible with MP10 and group H1 and FIme factors are incompatible with MP10 but compatible with H1. The majority of S. typhimurium cultures belonged to phage type 208; most of those that did not, belonged to types related to 208. Only a minority of their FIme plasmids were autotransferring. The remainder were mobilizable by F-like plasmids, and by group H1 and H2 factors, but not by the fi–I1 facter δ, or by plasmids of the I2, B, P, W, N and com 7 groups. The compatibility reactions of the autotransferring F1me plasmids were identical with those of the non-transferring members of the group, and both were large, single-copy plasmids.

The S. typhimurium strains of this series carried A or AK, and SSu resistance determinants: small, probably multicopy, non-transferring plasmids similar to those originally described in phage type 29 of S. typhimurium (Anderson & Lewis, 1965b).

These S. typhimurium cultures probably represent a clone of wide geographical distribution. The accurate epidemiological study of such clonal outbreaks requires, in addition to phage typing, precise identification of the plasmids harboured by the epidemic strains, and may have to be carried to the molecular level.

FIme plasmids were identified in other drug-resistant salmonellas, notably in a strain of S. wien which caused large outbreaks of mainly paediatric infection in Algeria, and also spread to Britain. An FIme plasmid was found in S. typhi phage type 44 from Algeria, in which the phage-restricting properties of the plasmid are responsible for the specificity of the type.

Two trials were carried out by 9 and 47 laboratories to evaluate the reproducibility and sensitivity of a standard technique for the isolation of salmonellas from animal feeding stuffs.

The trials involved the examinations of test samples containing known numbers of salmonellas by a buffered peptone water pre-enrichment technique. Statistical analysis of the results of the trials showed that the method was capable of detecting salmonellas in most probable numbers as low as 2·3 per 100 g and that no significant differences in performance were observed between laboratories.

The standard technique described is recommended for the examination of animal feed and conforms to international recommendations.