The distribution of phage types among 221 human strains of Salmonella paratyphi A in Indonesia was studied. Approximately 50% were phage type 5, a rare type elsewhere in the world. Most other isolates were the cosmopolitan phage type 1. The ratio of phage type 1–5 was compared for two cities on Java, Jakarta and Yogyakarta. The ratios were significantly different, phage type 5 predominating in Jakarta. The ratio of phage types among 10 S. paratyphi A strains isolated from Jakarta river water was similar to that found in Jakarta patients.

Bacteriologically proved cases of salmonellosis presenting at the University Hospital have increased nearly threefold since 1957. The most striking change has been a considerable increase in the incidence of Salmonella heidelberg and Salmonella derby in the last 5 years, probably resulting from hospital acquired infection.

About 80 cases of typhoid fever are reported each year in Jamaica. There has been little change in the prevalence of different phage types of Salmonella typhi since 1961. Paratyphoid fever is rare.

Standardized antimicrobial disk-sensitivity testing was performed on selected surviving salmonella strains since 1964. S. typhi has remained fully sensitive to all the agents tested except streptomycin. Other salmonellas, however have shown a significant increase in antimicrobial resistance since 1970. Most of this increase was due to multiple resistance in S. heidelberg and S. derby, and the survival and dissemination of these strains in the hospital environment may be related to antibiotic usage.

A galactose epimeraseless (gal E) mutant of Salmonella typhimurium was investigated in mice and calves for its suitability as a live vaccine. In mice, a very highly significant difference in the mortality rates was observed when vaccinated and non-vaccinated animals were challenged with virulent strains of S. typhimurium and S. dublin.

In calves, doses of 106 and above of gal E mutant injected subcutaneously provided highly significant protection both in terms of mortality and prevalence of symptoms when calves were challenged orally with S. typhimurium. However, there appeared to be a relation between the vaccine and the presence of renal lesions and before gal E mutants can be recommended, further work is necessary to determine the pathogenesis of these lesions.

The diagnosis of abortion in cattle caused by Salmonella dublin depends upon the isolation of the organism from either the products of conception, uterine discharges, vaginal mucus or milk together with serological evidence of active infection. S. dublin may be isolated when an active or a latent carrier cow aborts but in these cases an active infection will not be demonstrable. The retrospective identification of a case of S. dublin abortion may prove difficult as excretion of the organism is usually transient and the serum agglutinating antibodies frequently fall to low titres soon after the abortion.

Eight-hundred and one patients amongst 1912 referred for skin testing because of suspected allergies were found suffering from asthma due to the house-dust mite or from grass pollenosis. They were analysed in terms of sex, age of referral and age of onset of symptoms. Amongst children referred below the age of 10 with house-dust mite asthma the ratio of males to females was 3:1; with grass pollenosis 2–1:1, as expected. The sex ratio gradually became reversed with increasing age of referral, females overtaking males in the third decade. Female–male ratios increased to a mean of 1–8:1 in the fourth and fifth decades. Reliable ages of onset of symptoms were obtained in 388 males and 323 females. Of these, 280 males and 162 females experienced their first symptoms before the age of 10 whereas 96 males and 148 females first developed symptoms between 10 and 29 years of age. The remaining 12 males and 13 females showed their first symptoms after the age of 29.

During an 8-week period all specimens of stool passed by six nurses were examined for the presence of Escherichia coli and all isolations of this organism were serotyped. During the middle 4 weeks of the period the nurses ate a sterile diet. A smaller number of serotypes was isolated during the period of sterile diet than during the period when normal food was eaten. This finding supports the view that normal food is a source of strains of E. coli present in the bowel. Some new serotypes of E. coli did appear during the period of sterile diet. The possible sources of these are discussed.

The mechanism causing viable Francisella tularensis to lose virulence in aerosols has been investigated. Fully virulent organisms were found to be encapsulated and avirulent organisms from aged aerosols, decapsulated. Capsules were also removed by suspension of F. tularensis in hypertonic sodium chloride. The resulting naked, but viable, organisms were predominantly avirulent for guinea-pigs challenged intraperitoneally. Capsular material and cell walls were found to contain large amounts of lipid, about 50 and 70% (w/w) respectively, and to differ in lipid and sugar composition. Isolated capsular material was not found to contain a lethal toxin for mice or guinea-pigs, or to induce an immunological response in these animals to fully virulent F. tularensis.

Strains of California encephalitis virus (snowshoe hare subtype) were isolated from 8 of 475 pools comprising 23747 unengorged female mosquitoes of five species collected at three of six locations throughout the Mackenzie Valley of the Northwest Territories, Canada, from latitudes 60 to 69° N between 10 and 24 July 1976. Minimum field infection rates included 1:2734 for Aedes communis, 1:256 to 1:3662 for A. hexodontus and 1:911 to 1:1611 for A. punctor. Northway virus was also isolated from 1 of 3662 A. hexodontus mosquitoes collected at Inuvik (69° N, 135° W). Transmission of CE virus by A. communis infected by feeding on virus in defibrinated blood and incubation at 0, 13 and 23 °C for 13–20 days clearly demonstrates the importance of this species as a natural vector, and transmission of CE virus by Culiseta inornata after incubation at 0 and 13 °C following intrathoracic injection strengthens evidence of its role as a natural vector. Immunofiuorescence was less reliable than imunoperoxidase for detection of CE viral antigen in mosquito salivary glands.

Of 485 persons who replied to a questionnaire after attending a European Congress in September 1974, diarrhoea was experienced by 4 of 143 British residents and 2 of 342 visitors to the United Kingdom. This extremely low incidence of travellers' diarrhoea contrasts with the high incidence reported in travellers from countries with cool climates and north European standards of hygiene to countries where these conditions do not hold.

The extensive laboratory investigations of respiratory disease in the U.K. over many years have demonstrated the frequency with which influenza viruses, both A and B, are found each winter. Only rarely are none isolated.

These findings correlate well with other indicators of influenza such as increases in sickness benefit claims and in deaths attributed to influenza and pneumonia.

However, outside these demonstrable peaks of incidence influenza viruses have been found to circulate over considerably longer periods often first appearing as early as November and continuing through to April or even May. But there has been no regular or predictablepattern determined.

The period of 1968–76 has seen a series of differently developing influenza winter epidemics caused by a series of the H3N2 virus. The contributions of virus isolation and serology to influenza surveillance is discussed.

A simple method for the bacteriocine typing of Serratia marcescens without the use of induction was sought. The results of a mutual inhibition experiment with 89 unrelated cultures indicated that a bacteriocine-susceptibility method would give more discrimination between strains than would a bacteriocine-production method. A cross-streaking technique for bacteriocine-susceptibility typing without previous induction was developed, and its performance was compared with that of another susceptibility-typing method in which cell-free lysates of the producer strains were obtained by induction with mitomycin C.

Replicate typing of the same collection of cultures by both methods indicated that small variations in pattern were common and that larger variations occurred occasionally. Differences in pattern of less than two strong reactions in the mito-mycin-C induction method, and of less than three strong reactions in the cross-streaking method, should therefore not be taken as evidence that strains can be distinguished.

Sets of cultures of Ser. marcescens, 178 in total, from a number of supposed incidents of infection in hospitals, were used to evaluate the two bacteriocine-typing methods; all of the cultures were also O serogrouped. Comparison of the typing patterns of members of the same O serogroup from clear-cut incidents of infection confirmed that results of acceptable reliability could be obtained by either bacteriocine-typing method by the application of the appropriate 'difference' rule. When so interpreted, the cross-streaking method appeared to be slightly the more discriminatory.

The greatest discrimination between strains was obtained by the use of a 'hierarchical' typing system in which the strains were first O serogrouped, and the cross-streaking method of bacteriocine typing was then used to make subdivisions within O serogroups.

Water beds in use in this hospital were found to be contaminated with Pseudomonas aeruginosa. The addition of sodium hypochlorite, giving a final concentration of 200 parts/106 available chlorine, was found to be effective in preventing microbial contamination over a 6-month study period.

In a prolonged field trial a 4% chlorhexidine digluconate detergent scrub (HibiscrubR), that had earlier proved to be an effective hand disinfectant, was studied in hospital wards. Finger tips were found to harbour more bacteria than the hand dorsum and the samples collected from them yielded more information on the bacteriological and dermatological effects of hand disinfectants in practice.

In wards with a relatively low hand-washing frequency (less than 20 times in 8 hours) the bacteriological results resembled those obtained by in-use tests with volunteers. In the neonatal unit where the hand washing frequency was remarkably high, even occasionally over 100 times/8 h shift, an increase in the bacterial colony counts of the majority of the staff was recorded both before and after hand washing already after using the preparation for 1 week. Age, occupation and hand-washing frequency all correlated with the bacteriological results. Twenty-seven out of 37 persons complained of side effects such as wounds of finger tips and redness or heavy drying of the skin. Wounds, particularly on finger tips, resulted in the failure of disinfection. An increase in bacterial counts was sometimes noted without any dermatological or subjective changes. Drying of the skin was complained of less often when no increase in skin bacteria occurred.

After the changeover of washing practice to a detergent followed by a rinse with spirit solution containing chlorhexidine and glycerol a decrease was recorded in the bacterial counts. It is concluded that more attention should be paid to long-term testing of hand washing and disinfection methods to ensure optimum final results in practice. It is obvious that the knowledge obtained from short time in-use testing cannot be applied to all conditions of use.

The effect of ventilation on airborne contamination was studied in a new operating suite containing operating rooms with conventional ventilation (17−20 turnovers/h) and operating rooms with zonal ventilation, where the turnover in the central part of the room was˜80/h. The efficacy of the ventilation was first examined with gas tracer experiments and found satisfactory. Experiments using potassium iodide particles showed the transfer between adjacent rooms in the suite to be less than 10−3% with closed doors and from 1% to 2·5 × 10−2% when the doors were opened once a minute. The transfer between two adjacent operating rooms was calculated to be˜10−4%. There is thus little risk of spread of airborne infection between operating rooms.

Experiments with potassium iodide particles showed that in operating rooms with zonal ventilation the particle concentration in the centre of the room was about one-tenth that in the periphery; in conventionally ventilated operating rooms the concentration was about one-half. With bacteria-carrying particles generated by human activity the concentration in the centre of operating rooms with zonal ventilation was about half that in the periphery both during experimental activity and operations; in conventionally ventilated operating rooms it was about equal in both cases. Bacterial counts at the periphery were found to be lower in rooms with zonal ventilation (˜ 50 c.f.u./m3) than in conventionally ventilated (˜ 70 c.f.u./m3).

The ability of six different types of contamination control mats currently in use at the entrances to theatre suites and other clean areas to remove bacteria-carrying particles from theatre trolley wheels was compared. Marked differences in the effectiveness of this property were obtained; and all mats showed some disadvantages. Modification of one of the mats has resulted in improved efficiency under working conditions.

Analytical expressions have been derived for the exchange of air across doorways or similar apertures, in terms of the temperature difference between the spaces on both sides of the opening and the net volume of air flowing through this as a result of unbalanced air supply or extract. A simple allowance for turbulence which gives reasonable correspondence with observation is included. The formulae, which assume complete air mixing on both sides of the doorway up to the plane of the aperture, predict outflows from the warmer side, when there is an excess air supply to this side, which are progressively smaller than those observed as the temperature difference rises above 2–3 °C and the volume of excess air supply increases to produce an averaged outflow velocity greater than 0·1–0·15m/s. This seems to be due to lack of mixing of the warm outflowing air with the cooler air mass. A correction factor for this can be deduced as a function of the pressure difference due to the excess air supply. The limiting magnitude and general form of this function are compatible with a simple theoretical model of the air flow patterns involved.

The modification of Middlebrook's 7H11 oleic acid albumin agar medium by the addition of fresh bovine serum and lysed sheep red cells to encourage growth of Mycobacterium bovis is described. The improved medium was made selective by the addition of antibiotics and a comparative trial of this medium and the guineapig test in the isolation of M. bovis from badger tissues is reported. A close agreement between the two tests was found; the guinea-pig test detected 95% of all isolations and culture detected 91%.