An increase in the number of isolations of Mycobacterium xenopei from sputum suggested environmental contamination. The organism was recovered from water taps in 61 of 111 pairs of hot and cold water taps in one hospital, 20 of the 74 pairs in another hospital, but from only 3 of 61 pairs of taps in a third hospital and two of 34 pairs in private houses. Scotochromogens were recovered from taps in the first two hospitals only, and M. kansasii was isolated twice from the same tap in the first hospital. No mycobacteria were isolated from pigeon droppings or viscera, nor from patients' tooth brushes, tooth powder or razor debris. The source of contamination is not known.

Thirty-five consecutive infants admitted into hospital in Newcastle upon Tyne with acute respiratory disease had cough/nasal swabs and nasopharyngeal secretions taken. Both types of specimens were examined the fluorescent antibody technique for respiratory syncytial virus; isolation techniques were also used. Twenty-eight specimens of nasopharyngeal secretion were positive, as were 26 of the corresponding cough/nasal swab preparations. Respiratory syncytial virus was isolated from all but one.

Sixteen consecutive children who were only suitable for examination cough/nasal swab preparations were also investigated isolation and fluorescent antibody techniques for respiratory syncytial virus. Respiratory syncytial virus was isolated from eight, seven of whom were positive the fluorescent antibody technique. The use of cough/nasal swab preparations stained the fluorescent antibody technique, although not as efficient as nasopharyngeal secretions, may have a place in the rapid diagnosis of respiratory virus infection in older children and children in general practice. The importance of rapid diagnosis for respiratory virus infection in relationship to antiviral therapy was also discussed.

Lysogeny was detected in 98·8 % of the 343 Escherichia coli O119: B14 strains. A suitable indicator strain E. coli KS was selected to demonstrate the presence of temperate phages in this serotype. A great diversity in the temperate population was observed based on their lytic patterns and neutralization studies. No definite relationship could be established between the biochemical reactions and the flagellar antigens of the lysogenic strain and its temperate phage though some temperate phages released by E. coli O119:B14 strains with certain flagellar antigens did give specific lytic patterns and were serologically identical. Lysogenic strains, which did not release temperate phages spontaneously, were u.v. in-ductible. Cross-reactions with lysogenized colonies which were immune to corresponding phages also confirmed diversity of temperate phages in E. coli O119: B 14.

The use of gauze swabs in drains or sewers to clarify the path followed by a salmonella from source to human host has been reviewed in the light of experience gained in Cardiff over 15 years. This period has seen a marked change in attitudes to salmonella epidemiology in that infected food is now regarded as of greater importance than infected food handlers. In these 15 years, butchers, abattoirs and knackers' yards, markets and bakehouses have been monitored. In the bakehouse survey the existence of staff infection was demonstrated by sewage examination. Sewage investigation has also been used to show frequent entry of salmonellas into households in a residential estate. The estate was carefully chosen to exclude salmonellas from industrial sources and shops. The frequent finding of infection in this sewage implies that a commonly consumed heavily infected food item is involved. The wide range of serotypes isolated suggests an animal usually fed on infected animal feed. Poultry and pigs are put forward as animals liable to spread salmonellosis to man.

It is hoped that clarification of the salmonella pathway may eventually lead to measures likely to prevent the transmission of infection to man. It is also suggested that swabs placed in abattoir drains serve as an economical method of obtaining warning of a persistent build-up of contamination. The persistence of a serotype in an abattoir is not infrequently followed by human infection.

The results of immunization of 523 children from 9 months to over 5 years of age with two attenuated measles vaccines, ‘Denken’ and ‘Biken’, are described. The clinical reactions following vaccination with both vaccines were mild, but Denken vaccine produced more rashes than the Biken vaccine. The serological conversion was satisfactory for both vaccines but a higher titre of neutralizing and haemagglutination-inhibiting antibodies was found in children immunized with Denken vaccine. The incidence of severe reactions or complications was negligible in this trial. The immunity to diphtheria or tetanus was not altered by vaccination with live measles vaccine.

Coxsackie A 6 virus, strain V 29, originally isolated from Aedes polynesiensis in Fiji, was found to survive in A. australis for 5 days after intrathoracic injection and for 6 days after feeding on viraemic mice, and in Culiseta tonnoiri for 8 days after feeding.

The virus level in both fed and injected mosquitoes fell steadily after infection and never exceeded the original level.

No virus transmission was obtained in 46 successful second feedings on days 10–14 with A. australis, but three transmissions were obtained with C. tonnoiri, two on day 10 and one on day 13, from 12 successful second feedings.

The use of a gamma radiation process for the elimination of Salmonella from frozen meat is considered with particular reference to the treatment of boned-out horsemeat and kangaroo meat imported into the UK and intended for use as pet meat.

Examination of dose/survival curves produced for several serotypes of Salmonella in frozen meat shows that a radiation dose of 0·6 Mrad. will reduce a population by at least a factor of 105. The influence on the radiation resistance of salmonellas of such factors as preirradiation growth in the meat and temperature during irradiation have been examined and considered. It is also demonstrated with both preinoculated and naturally contaminated meat that postirradiation storage in the frozen state does not lead to the revival of irradiated salmonellas.

The properties of Salmonella survivors deliberately produced in meat using conditions of irradiation designed to simulate a commercial process are studied after six recycling treatments through the process. There were no important changes in characteristics normally used for identification of Salmonella but radiation resistance was lowered. Survivors grown in situ in meat after irradiation showed an abnormally long lag phase, and removal of competitive microflora in meat by the radiation treatment can influence the growth of salmonellas.

A method of drying bacteria is described, in which the bacterial suspension was made in 40% sodium glutamate, and 0·1 ml. volumes of this in 8 ml. ampoules were dried in vacua while being held in a water bath at 25°C. After 1 hr. with the pump still running, the ampoules were immersed in water at 100° C. The partly dried suspension expanded rapidly into a homogeneous white foam. After 30 min. the ampoules were taken off the manifold; small tubes containing dry P2O5 were inserted in the ampoules which were then sealed in air. Preliminary results with three organisms, Salmonella ndolo, Staphylococcus aureus and Serratia marcescens showed high survivals immediately after the ‘foaming’ period, and good stability after 1 or 2 days at 100°C.

The postnatal decline of maternally acquired rubella antibody was studied in a large group of infants. A high degree of variability was found in the rate of antibody decline (half-life). Ninety-two babies had rubella antibody half-lives lying between 14 and 70 days and three had values considerably higher. There was no significant difference between the rubella antibody half-lives of the sexes. The antibody titre at birth was weakly correlated with both birth weight and gestational age. There was a highly significant positive correlation between the baby's antibody titre at birth and that of its mother. There was a positive relationship between the half-life and the persistence of rubella antibody. Some babies had no detectable antibody by 2 months whereas others still possessed antibody at 9 months. It was found that the relationship between the half-life and the rubella antibody titre at or near birth could be described by a rectangular hyperbola.

In previous work in this laboratory, Mycoplasma suipneumoniae was recovered in liquid medium from 13 % of individual cases and 18 % of outbreaks of enzootic pneumonia in pigs. In the work now described, however, these recovery rates, when judged by the same criteria, were 45 and 75 %, respectively. As there was evidence to suggest that this second series of pneumonic cases was less suitable for cultural examination than the first series, some of the other factors that might have improved the recovery rate were investigated.

Some improvement was probably achieved by inoculating the liquid medium with three or four different dilutions of pneumonic tissue, each dilution always being in duplicate, and by incubating the inoculated tubes for over 3 weeks before discarding them.

A second advantage could have derived from the fact that all batches of liquid medium were tested for their ability to support the growth of M. suipneumoniae before being used to culture field material.

The effect of varying one constituent at a time was observed in controlled experiments: different batches of pig sera had a marked, variable effect on the growth of both M. suipneumoniae and Mycoplasma hyorhinis; medium made with purchased Hartley's broth was found to be superior to medium incorporating broth made in this laboratory, more so for the growth of M. suipneumoniae than M. hyorhinis; the incorporation of yeast extract made in this laboratory gave a marginal advantage for the growth of M. hyorhinis; and both mycoplasmas grew equally well in medium containing or lacking thallium acetate.

Some batches of medium were, by chance, markedly selective for the growth of M. suipneumoniae compared with M. hyorhinis. As the full reasons for this were not known, attempts were made to develop selective media in a more direct way. One such medium contained 5% pig serum and 15% horse serum, and a second was of similar composition, except that the pig serum used inhibited preferentially the growth of M. hyorhinis compared with M. suipneumoniae. Both media markedly favoured the growth of M. suipneumoniae when tested separately with cultures of M. suipneumoniae and M. hyorhinis. The second medium yielded M. suipneumoniae when inoculated with a 10-1 dilution of a culture of M. suipneumoniae and a 10-2 dilution of a culture of M. hyorhinis, whereas a standard batch, of liquid medium, similarly inoculated with M. suipneumoniae did not yield this mycoplasma until the M. hyorhinis culture included in the inoculum was diluted to 10-6.

Both selective media, when tested on a small number of field cases, gave improved isolations of M. suipneumoniae compared with the routine batches of liquid medium used initially.

Considerable difficulty was experienced in producing a sufficiently high level of antibodies to M. hyorhinis in pig sera and to M. suipneumoniae in rabbit sera. This exacerbated the problem of isolating and identifying M. suipneumoniae from field cases of enzootic pneumonia by this cultural method.

Results from clinical isolations confirmed that mercury resistance is common among antibiotic-resistant strains of Staphylococcus aureus present in a large general hospital although the correlation is not as high as that found by Moore (1960).

The distribution of mercury-resistant strains among infections and carriers in surgical, medical, obstetric and geriatric patients and staff was studied. Attention was directed to the distribution among carriers since there are fewer extraneous factors operating among them, and a statistical analysis was made on the total number of mercury-resistant strains and the number of non-endemic strains; this latter figure was obtained by subtracting the dominant type 80/81, which is nearly always mercury-resistant and antibiotic-resistant, from the total. Analysis showed the geriatric patients to have a significantly higher proportion of mercury-resistant strains in both cases, and obstetric patients to have a significantly lower proportion when the total number of mercury-resistant strains was considered. Among the surgical, medical and staff categories, no significant difference in proportions could be found although a trend, in that order, of decreasing proportions of mercury-resistant strains present was noted.

In those cases infected on admission with tetracycline-resistant strains, although mercury-resistant strains still predominate, mercury-sensitive strains make a sizeable contribution. This is a reflexion of their dominance in the non-hospital environment.

A 10-month follow-up of 14 Fijian children suffering from molluscum contagiosum showed that the condition could last from about 6 months to about 3 years, but that any one lesion was present for only 2 months. There could be temporary relief from new lesions for at least 2 months; when complete remission occurred, it could be comparatively rapid. It is suggested that individual lesions should not be treated, in order to avoid scarring and because of their relatively rapid disappearance.

Membrane and soluble fractions of one genital and two oral strains of Mycoplasma hominis were compared by immunodiffusion and polyacrylamide gel electrophoresis. Differences were demonstrated between the membrane antigens of the three strains by immunodiffusion, and the membrane proteins also gave dissimilar patterns in polyacrylamide gel electrophoresis. The soluble fractions gave identical lines in immunodiffusion tests and similar patterns in polyacrylamide gel electrophoresis.

When the strains were cross-titrated in metabolic inhibition (MI) and indirect haemagglutination (IHA) tests, statistical analysis of the results revealed significant differences between the strains. Previously, growth-inhibition, MI and IHA activity was shown to be associated with the membrane antigens of M. hominis, so the intraspecies differences revealed by MI and IHA correlate with the differences in the membrane antigens demonstrated by immunodiffusion. Growth-inhibition tests, which might also have been expected to show intraspecies differences, did not do so, probably because of the insensitivity of the test. In contrast to MI and IHA, complement-fixation (CF) tests revealed a high degree of relatedness between the strains. This is consistent with the observation that the soluble antigens of M. hominis participate in the CF reaction, and that the soluble antigens of different strains are identical in immunodiffusion tests.

Fourteen cases of enzootic pneumonia, nearly all of which had presented diagnostic difficulties using the metabolic-inhibition test, were re-examined using specific pig antisera in the passive haemagglutination test (PHA). All proved positive for Mycoplasma suipneumoniae, indicating that the test, used in this manner, might be particularly valuable for routine diagnosis.

The PHA test was also used to demonstrate antibody to M. suipneumoniae in pneumonic tissue and the associated bronchial lymph nodes.

To allay our concern that cross-reactions might interfere with this and other serological tests—the complement-fixation test (CF) and precipitation in agar-gel—the specificity of our reagents and the antigenic relationships of Mycoplasma hyorhinis, Mycoplasma granularum, mycoplasmaB3, Mycoplasma hyopneumoniae and three strains of M. suipneumoniae (including cloned and uncloned isolates of the J strain) were studied in various ways. Antibodies to medium constituents occurred in rabbit antiserum but did not present a problem with pig antisera. These antibodies were successfully absorbed from the rabbit antisera but it was not possible to remove medium constituents from the antigens used to produce antisera in rabbits by repeated washing.

By all these tests, the main species of mycoplasmas studied seemed to be anti-genically distinct. No major antigenic differences between the three strains of M. suipneumoniae were revealed by the PHA test and the CF test; a slight difference in the precipitation lines of one of these strains (MG) in agar-gel might have indicated an antigenic variation or been a measure of some other factor.

Reasons for the accumulation of mercury-resistant strains of Staphylococcus aureus in hospital have been studied. A collection of paired strains, that is staphylococci similar in every respect except sensitivity to mercury salts, was made. Tests were made in an attempt to demonstrate a link between mercury resistance and some other factor which might aid survival, viz. resistance to drying and heat, production of bound coagulase, growth in the presence of sublethal amounts of tetracycline, survival in human blood at 37°C. and uptake by polymorphs at 30°0. and 37°C., development of resistance to antibiotics and competition in mixed cultures. It was not possible to demonstrate any consistent link between mercury resistance and any of these properties. Paper strips impregnated with the mercurial diuretic, Mersalyl, were shown to differentiate between mercury-resistant and -sensitive strains in vitro. Furthermore, development of resistance to mercury by passage in mercuric chloride-broth was demonstrated.

It is proposed that mercury resistance has developed as a result of exposure to the mercury ion. Mercurial diuretics have been frequently used in medical and geriatric patients and it is among these that the higher carrier rates of mercury-resistant strains are found even when the local endemic strain is disregarded. In obstetric patients, where mercurials are seldom used, mercury-resistant strains are rare.

Nasal carriage of factory workers exposed to mercury products showed that this group is likely to carry resistant or partially resistant strains.

In an established burns centre which moved from an old building to new purpose-designed premises, colonization rates of patients' burns with Staphylococcus aureus, Pseudomonas aeruginosa and other Gram-negative bacilli were not reduced. Colonization rates with Streptococcus pyogenes increased but the increase was mainly due to multiple importations in the new premises of a strain of higher communicability than any seen in the old.

In the first 32 months in the new environment 10 patients were found colonized with pseudomonas on admission and 20 became colonized in the unit. A much higher proportion of patients with burns of more than 30% body surface became colonized than of patients with less. About one-third of the above 20 patients became colonized with strains already isolated from another patient; all but one of them had small area burns. Cross-infection was not observed from numerous heavily colonized patients with high percentage burns. This paradox is discussed in detail. Basin outflows in the new premises became colonized with P. aeruginosa of two serotypes not found on patients in this unit.

Methods for demonstrating antibody to wart virus by complement fixation and passive haemagglutination tests are described and compared with the precipitin test of Almeida & Goffe (1965). The results reveal the much greater sensitivity of the passive haemagglutination method, particularly in the detection of the immunoglobulin M class of antibody. Both complement-fixing and precipitating antibody were detected in sera from patients whose warts had undergone a spontaneous resolution.

The presence of antibody to wart virus was demonstrated in sera from persons who had had warts up to 10 years previously, and in a few cases from those who thought they had never had warts.

The antigenic identity of virus from hand warts and plantar warts of the simple and mosaic types was revealed, and some evidence was obtained for similar identity of the virus from genital warts.

The effect of various concentrations of sodium thioglycollate (0–0·05 %) on the recovery of spores of four strains of clostridia was investigated. The results showed that thioglycollate at a concentration of 0·01 % can be inhibitory to some clostridia. However, the results also indicated that the inhibitory effect is dependent upon the composition of the growth medium. The presence of glucose appeared to be particularly important in reducing the inhibitory effect. These findings support the view that the use of sodium thioglycollate in sterility test media should be discontinued.

All respiratory illnesses which were reported to the medical officers between September 1966 and December 1967 on a Royal Air Force station of 350 men were studied virologically.

Three periods of increased respiratory infections were observed: two occurred in the autumn, one in each year, and the third in the winter during January and February. The autumnal outbreaks were associated mainly with rhinovirus infections, and high isolation rates (82·1, 65·9%) were achieved at these times. Few of the illnesses during the winter outbreak could be diagnosed in the laboratory, and no evidence was found of infection with ‘coronaviruses’.

Despite the entrance of 30 fresh recruits direct from civilian life every 5 weeks, the respiratory infections encountered on the station were very similar to those in the local population and were not predominantly infections with adenoviruses, Coevirus, and Mycoplasma pneumoniae, as previously reported from larger military recruit centres.

Haemophilus influenzae type b was isolated from 4·5% of outpatient children living in various parts of Kampala city and its surroundings. In contrast, this serotype was carried by up to 53 % (average 29 %) of 14 to 18 children living as a group in an orphanage. This finding indicates that the high carriage rate for this serotype demonstrated by Turk (1963) in a group of orphanage infants in Jamaica was not an isolated finding, and that it may be expected where large groups of children live together.

H. influenzae type b did not appear to be a readily transmitted organism even in that group of children with a high carriage rate. This suggests that in ordinary open communities the transmission of this serotype from one household to another may be an extremely rare event.