A method is presented with which the mechanical cleaning effect of flushing disinfectors can be estimated independently of the thermal disinfecting effect of the hot flushing water. This makes it possible to specify the demands to be placed on the disinfecting effect of flushing with water of 85°C or more.

Bacillus stearothermophilus spores suspended in faeces were used as indicators because of their non-sensitivity to the hot-water temperature. Their elimination by flushing could thus be attributed to the mechanical effect of the water and not to the disinfecting effect of the temperature. A simple bacteriological technique was used, and the elimination factor (EF) was calculated as the ratio of the number of micro-organisms in the contamination before and after flushing. By using flushing water below 50°C for 130 s the EF on a bedpan was about 104–106. The effect of flushing with water of the same temperature for only half that time was somewhat weaker and when the temperature was raised to 85 °C after half the flushing time the effect was somewhat stronger.

It can be presumed that the conventional disinfecting phase with hot (85 °C) water for about 45 s in the commonly used flushing units could be substantially shortened and the costs of their use thereby reduced.

Leptospires (Leptospira interrogaus serovar pomona) grown in chemically defined medium were immunogenic when given intradermally in humans if the leptospires were killed with formalin but not if they were boiled. Boiled leptospires were immunogenic for rabbits and hamsters and protected hamsters from challenge infection. On the other hand, boiled leptospires of the biflexa complex, serovar patoc, did retain some immunogenicity in humans, but the antisera did not protect hamsters against challenge with serovar pomona.

In skim milk obtained from susceptible cows after intramammary and intravenous inoculation (primary infected milk), foot-and-mouth disease (FMD) virus type 01 was slower inactivated by heat treatment than virus that had been added to pre-exposure skim milk.

Residual virus infectivity in heated primary infected milk was more efficiently detected in bovine thyroid cell cultures than in secondary pig kidney (PK2) cell cultures.

Untreated primary infected milk was found to inhibit both FMD-virus and vesicular stomatitis virus plaque formation in PK2 cells, suggesting the presence of interferon. The results of further tests confirmed that the interfering activity in unheated primary infected milk was indeed caused by an interferon.

Interferon excretion in primary infected milk was investigated using a series of milk samples from three cows. Maximum interferon titres were found after 24 h, coinciding with or shortly after the first virus excretion peak. The results are discussed with particular reference to the use of primary infected milk in studies of the thermal inactivation of FMD-virus.

Oral treatment of mice with various doses of neomycin or polymyxin B was performed in order to determine which dose caused substantial suppression of aerobic gram-negative rods. In addition the effect of the various doses on Streptococcus faecalis and on other factors of the colonization resistance (CR) of the digestive tract were studied. It was found that polymyxin B was effective in suppressing sensitive gram-negative bacteria following daily doses of 3·2 mg/ mouse, and that even extremely high daily doses of 9·7 mg/mouse did not affect the CR. Neomycin was effective in suppressing Enterobacteriaceae species following oral daily doses of 5·4 mg/mouse. With this dose, however, the CR was somewhat decreased which was also evidenced by the increased concentration of beta-aspartyiglycine in the faeces and the increased size (weight) of the caecum in these animals. Suppression of Sir. faecalis was seen from doses of 24 mg/mouse on.

Swedish nationals about to travel abroad were immunized against typhoid with a monovalent heat-inactivated vaccine which was administered intra- or subcutaneously. No major differences in serum antibody response were noted in the two groups of vaccinees as determined with direct agglutination and indirect hemagglutination techniques. As the intracutaneous route caused fewer adverse reactions this way of administration seems to be preferable.

Sixteen strains of leptospires were isolated from surface water (14 in England and 2 in Italy) and were classified. They were all saprophytic, and nine of them belonged to known serovars: the others were found to represent new serovars within already known serogroups.

The present method of analysis of data from comparative field trials of acuterodenticides was compared with two alternative methods of analysis, using computer simulation techniques. One of the proposed alternative analyses, the use of post-treatment census takes as a percentage of pre-treatment census takes in an analysis of variance, was found to be more accurate, to avoid a theoretical difficulty associated with the present method, and is computationally much simpler.

Nineteen (22·9%) of 83 sera collected before vaccination from adult volunteers aged 21–64 years were without neutralizing antibody to poliomyeitis at levels of 0·15 i.u./ml for types I and II and 0·1 i.u./ml for type III. Some correlations were found between the history of previous vaccination and the presence of antibody but these were not well defined.

Vaccination with a single dose of trivalent oral polio vaccine elicited fourfold or greater antibody responses to one or more poliomyelitis types in 53 (63·9%) volunteers, the percentage antibody responses being inversely related to the titre of antibody present before vaccination. Types I, II or III poliomyelitis virus were recovered from 76·8 % of faecal samples collected 1 week after vaccination. The percentage recovery progressively declined thereafter until virus was recovered from 10·5 % of samples collected 6 weeks after vaccination.

Type for type, the titres and percentages of antibody responses and virus shedding in faeces were similar following trivalent oral poliomyelitis vaccines whether prepared in monkey kidney or human diploid cell substrates. Some change in reproductive capacity temperature (r.c.t./40) marker was found in faecal isolates from volunteers vaccinated with monkey kidney and human diploid grown vaccines but no change in ‘d’ marker was found.

A large proportion of postoperative infections after clean surgery are thought to be exogenous. For aerobic bacteria different routes of transmission have been thoroughly studied. Airborne infection has been considered very important in infections after total hip replacement (Charnley, 1972). Anaerobic non-sporing bacteria have been found in deep late infections after total hip replacement (Kamme et al. 1974; Schwan et al. 1977; Petrini, Nord & Welin-Berger, 1978). However, infections caused by anaerobic bacteria have been considered endogenous, and little is known about the routes of transmission for these bacteria.

Two commercially available baby milks, one ‘biologically acidified’, the other ‘non-acidified’, and a traditional weaning food, millet gruel, were prepared and stored under village conditions in West Africa. Increases in total colony count and in number of Bacillus cereus, Clostridium welchii, Staphylococcus aureus and Escherichia coli were determined in these products when stored as commonly practised at ambient temperatures over a period of 8 h. Poor hygiene during preparation was indicated by readily detectable numbers of coliforms and E. coli in freshly prepared samples of each of the milks, though the cooked local gruel seemed less vulnerable in this respect. The rate of increase in the numbers of these organisms was lower in the acidified milk when prepared with unboiled water containing high numbers of coliforms and E. coli. Increases in total colony count and in numbers of Staph. aureus were also less marked in the acidified milk. When food was not eaten soon after preparation the problem of bacterial overgrowth was as great with the local gruel as with the considerably more nutritious reconstituted milks.

Serum proteins adsorbed from the culture medium were detected in Mycoplasma bovis antigens, the number and type of proteins depending on the serum used in the medium. The α-globulins cross-reacted with α-globulins from different types of sera but the γ-globulins did not. The removal of non-specific medium antibodies by absorption showed that they affected the gel diffusion and growth precipitation tests, producing cross-reactions between M. bovis and M. bovigenitalium, but that the complement fixation, tube agglutination, and growth inhibition tests were not similarly affected. The presence of serum proteins in the antigens changed their specific reactivity in all the tests. The production of antibodies to serum proteins was increased by the use of an adjuvant, but it appeared that production of specific antibodies to the mycoplasmas was not.

Laboratory tests indicated that the optimum concentration for pyriminyl in rat baits was between 1% and 3%. In field trials in which 0·5% pyriminyl (the concentration in commercial use) was compared with 2·5% zinc phosphide for the control of rats on farms, the pyriminyl treatments were significantly less effective than the zinc phosphide even when the poisoned baits were left down for 7 days instead of 1 day after prebaiting. Both poisons were as effective in medium oatmeal bait as they were in medium oatmeal containing 5% corn oil and 5% sugar.

The pathways of infection in swine vesicular disease have been studied by (i) an estimation of the amounts of virus required to produce infection by different artificial inoculation procedures; (ii) the distribution and amounts of virus in various tissues of pigs killed at intervals after contact infection; (iii) an investigation of the susceptibility to virus infection of pig tissue explants.

The results show that pigs can be infected by a number of pathways and that the skin, as the most susceptible tissue, is probably the most frequent route of infection.

A Biap slit sampler and a Casella Mk 2 slit sampler were studied in an orthopaedic operating theatre. Both showed similar bacterial counts in the range of 74–640 c.f.u. (colony forming units)/m3. During operations, an average count of 220 c.f.u./m3 (range 52–482) was obtained. A close relationship was demonstrated between the number of airborne bacteria and the frequency of traffic through doors.

We conducted a survey during the period from 1974 to 1976, to determine the distribution of Plesiomonas shigelloides in human faeces, the intestinal contents of cattle, swine, poultry, dogs, cats, fresh water fish, and river water and sludge from wet riverbeds in the vicinity of Tokyo. Isolation of the organisms was performed by using Salmonella-Shigella (SS) agar and deoxycholate-hydrogensulphide-lactose (DHL) agar plates.

P. shigelloides was isolated from 3 (0·0078%) of 38454 healthy Tokyoites, 37 (3·8%) of 967 dogs, 40 (10·3%) of 389 cats, 25 (10·2%) of 246 fresh water fish, 64 (12·8%) of 497 river water samples, and 2 of 19 (10·5%) sludge samples.

Of 302 strains isolated, from dogs, cats, fresh water fish, river water and healthy carriers, 196 were typed to 50 serovars. Most of the serovars were found to be similar to strains isolated from patients with gastroenteritis due to P. shigelloides.

A simple method for preparing radial haemolysis gels for rubella antibody screening is described. In use it gave clear zones of haemolysis when a standard serum was tested at dilutions down to 5·6 i.u./ml rubella antibody. In five lab oratories 8404 sera were screened by the method and the results were read by comparing zones of haemolysis with that of a standard serum diluted to contain 15 i.u./ml antibody. A zone ⋝ 15 i.u./ml, indicating immunity, was given by 7433 (88·4%) of the sera. No zone indicating susceptibility was seen with 748 (8·9%) sera. Small zones, < 15 i.u./ml standard, were given by 189 (2·2%) sera, and in only 34 cases (0·4%) did non-specific haemolysis interfere with the test readings. Further testing of the radial haemolysis negative and low positive sera by the haemagglutination inhibition test gave rise to some discrepant results which are discussed.

A microbiological survey of over 400 sanitary dressings is reported: large numbers of bacteria are present, including species indicative of faecal contamination. The need for an effective bactericide in chemical bin exchange systems is thus demonstrated. Screening trials of several candidate formulations have been undertaken: buffered sodium metabisulphite, releasing sulphur dioxide as a vapour-phase bactericide, has now been introduced as an effective bin exchange system.

A total of 475 Salmonella strains belonging to 5 serovars, isolated from a pig farm which had been heavily contaminated with Salmonella for the past 2 years were tested for antibiotic susceptibility and detection of R plasmids. Thirty-three Escherichia coli isolates from the same farm were also examined in a similar way.

Out of 475 strains 348 (73·2%) were resistant to one or more antibiotics such as tetracycline (Tc), streptomycin (Sm), sulfadimethoxine (Su), chloramphenicol (Cm) and kanamycin (Km), and 247 (85·2%) out of 290 strains belonging to 3 serovars examined harboured conjugative R plasmids. There was no change in the pattern of drug resistance during this survey nor any variation in the pattern of resistance of R plasmids, whatever the serovar. The antibiogram pattern Tc Sm Su, mainly S. typhimurium, was common among Salmonella strains. Among the transferred resistance patterns, the thermosensitive R plasmids conferring the Te marker detected in this study were Fi-, and belonged to incompatibility group H1, whereas the R plasmids conferring Sm Su resistances which coexisted in the same host were Fi+, and compatible with the reference R plasmids tested. The la plasmid conferring Cm resistance alone was isolated from S. anatum and the FII plasmid conferring Sm Km resistances was also isolated from S. typhimurium. In contrast, the 33 E. coli strains examined were resistant to three or five antibiotics and most of the resistance markers were located on conjugative R plasmids. la plasmids conferring Cm resistance alone or FIT plasmids conferring Cm or Km markers were common in the E. coli strains. H1 and H2 plasmids conferring multiple resistance markers were also found in them. The genetic properties of R plasmids derived from Salmonella or E. coil strains are compared, and the potential spread of R plasmids between strains of Salmonella andE. coli is discussed.

A total of 882 samples of settled sewage, sewage sludges and final effluents from eight sewage treatment plants were examined for the presence of salmonellas. Of these samples 68% were positive, isolations being made most frequently from settled sewage (85%), raw sludge (87%) and anaerobically digested sludge (96%). Fewer isolations were made from final effluent (24%) and processed sludges (58%). Samples usually contained less than 200 salmonellas/100 ml and arguments are presented that such concentrations should not lead to disease in animals if suitable grazing restrictions are followed.

Lugol's solution destroys the biological activities of Newcastle disease virus (NDV) after 15 s incubation at 37 °C. The rates of inactivation are slower at lower temperatures and at acid pH. At 4 °C and pH 5·8, the functions associated with the virus membrane, (haemolysis (HL), cell fusion and infectivity) are inactivated within 32 min, while haemagglutination (HA) and neuraminidase (N) are resistant to inactivation for serval hours. Adjustment of NDV, Sendai and influenza A virus allantoic harvests to pH 5·8 and subsequent treatment with undiluted Lugol's solution (pH 5·8) for 15 min has a minimal effect on HA but results in complete loss of infectivity. It is suggested that iodination could be a useful method for vaccine production with membrane-bound viruses. It is postulated that the separation and dissociation of the membrane-associated properties of paramyxoviruses from the glycoprotein functions is due to the higher affinity of iodine for the lipids. Iodine could react with the carbon–carbon double bond (C=C) of the unsaturated fatty acids. This could lead to a change in the physical properties of the lipids and membrane immobilization.