Two mincing machines were cleaned by different methods, i.e. (a) a detergent/ sterilizer method and (b) scrubbing parts in boiling (98·8° C.) water. Initial results indicated that, on reassembly, post-treatment contamination took place. Efforts to clean each machine as consisting of two distinct parts, (a) the casing and (b) removable parts, were more satisfactory. Four other mincers which could be completely dis-assembled were satisfactorily cleaned, but only in terms of percentage organisms surviving and not in terms of actual numbers surviving.

Ferrets infected with influenza virus A2/Hong Kong/3/68 responded with a febrile reaction; the temperature was elevated by 1·0°C. or greater to a level of 40°C. or more. In addition, relatively high titres of virus were recovered from nasal washings taken 3 days after virus infection, serum antibody was produced, increased nasal protein was detected and nasal washings contained both HI and neutralizing antibody. Of four ferrets immunized with 400 CCA units of inactivated influenza virus A2/Aichi/2/68 in saline, only one produced detectable serum HI antibody, and none produced detectable nasal antibody. These ferrets were subsequently found to be susceptible to intranasal infection with influenza virus A2/Hong Kong/3/68. Thus, the temperature response, the titre of virus recovered from nasal washings and the serum HI antibody response found after virus infection was similar to that found after infection of non-immunized ferrets. However, the increase in protein concentration and the titre of HI and neutralizing antibody found in nasal washings after virus infection was detectably less than that found after virus infection of non-immunized ferrets.

Four ferrets were immunized with 400 CCA units of inactivated A2/Aichi/2/68 virus in adjuvant 65, and these ferrets produced relatively high titres of serum HI antibody but no detectable nasal antibody. After subsequent virus infection with influenza virus A2/Hong Kong/3/68, these ferrets showed a modified temperature response, reduced titres of virus in nasal washings compared to that found in nasal washings from non-immunized ferrets, no increase in nasal protein and no detectable nasal HI antibody. Thus, immunization with inactivated virus in adjuvant 65 resulted in a significant modification of the response of ferrets to challenge virus; however, the immunity was not complete, and appreciably less than that found after infection with live homologous virus.

Newcastle disease virus has been shown to survive when airborne in small particles, both in the laboratory and in the open air. Field outbreaks have been studied and viable virus has been recovered from the open air short distances downwind of infected premises. Vaccination of birds leads to a great reduction in the amount of virus liberated into the air.

TRIC agents do not multiply in mouse peritoneal macrophages in culture but have a toxic effect on them, whereas they multiply readily in BHK-21 cells. Sections of macrophages and of BHK-21 cells fixed during the first 90 min after inoculation were examined by electron microscopy. Macrophages ingested all forms of the organism, which were eventually degraded in lysosomes. However, elementary bodies were distinguished from other TRIC particles by the delay in their transfer to lysosomes. BHK-21 cells ingested elementary bodies selectively, and in these cells the organisms were neither found in lysosomes nor degraded. Instead they showed morphological changes that probably represented an early stage of development.

Necropsy blood from cases diagnosed as dying from influenza A was examined for specific antibody in the IgG, IgA and IgM fractions and a specific diagnosis of recent infection was made if either IgM or IgA antibody and low titres of IgG antibody were found. By these criteria a diagnostic rate of 77% was found in those cases from whom no virus was isolated. The use of infected cell monolayers grown on polytetrafluoroethylene-coated slides gave a simple method of carrying out these antibody assays, and the use of necropsy blood did not require any special methods of transport of specimens to the virus laboratory.

A survey of the staphylococcal infections occurring in a general hospital over a period of four and a half years showed that multiple-resistant strains of phage type 77 were endemic in the medical and surgical wards. Strains of this phage type were uncommon among patients attending the casualty department, and those found were usually either fully sensitive to antibiotics or resistant to benzyl-penicillin only. Regular monitoring of patients admitted to the intensive-care unit showed that 58 % of staphylococcal infections in such patients were present at the time of admission to the unit. Although the wards thus constituted a significant reservoir of infection for the intensive-care unit, there was no evidence to suggest that the return of patients from the unit to the wards was responsible for the transfer of infection in the opposite direction. The possibility of reducing the numbers of multiple-resistant staphylococci in the general wards, by the screening of all new admissions for the presence of tetracycline-resistant strains, appears to be impracticable in this area.

The effects of oral chemotherapy and stay in hospital on the antibiotic resistance patterns of faecal coliform flora were studied. The coliform flora of 64% of 25 patients who were not receiving antibiotics was sensitive to all drugs tested. Hospitalization alone did not affect this proportion. The administration of tetra-cycline or ampicillin to patients, whether at home or in hospital, significantly increased the percentage of resistant bowel coliforms. Tetracycline showed a significantly greater effect than ampicillin. There was no significant increase in the percentage of patients with resistant flora after treatment with amoxycillin.

Sub-lethal exposure of Aspergillus fumigatus spore suspensions to formalin resulted in prolongation by 1–22 days of the period of less than one day normally needed by spores to produce visible growth in Sabouraud's liquid medium at 37° C.; the degree of delay depended on the concentration of formalin and the duration of exposure, and was due to an increase in the germination-time of spores. The formalin concentration could be adjusted so as to affect the germination-time of almost all spores in a suspension without reducing viability. The effect on germination was not abolished by thorough washing or treatment with sodium sulphite. The spores of four different strains of A. fumigatus and of cultures aged 3 to 14 days reacted similarly to formalin treatment. Although of greatly reduced virulence for mice, affected viable spores were still capable of producing infection and death following intravenous inoculation, provided they were not eliminated by the host before germination occurred.

The high incidence (80·1%) of Pseudomonas aeruginosa pyocine type 1 in bovine mastitis in Israel suggested some degree of selectivity under local conditions. Contrary to other reports, cattle and calves showed a high rate of faecal carriage of this organism. The water supply on farms was often contaminated. The presence of certain pyocine types in the udder, gut or water occasionally led to their transmission from one reservoir to another; however, many types did not seem to spread.

P. aeruginosa was found in association with infections in various animals and was present in many locations such as a mouse breeding house and a chick hatchery.

Skin reactions have been produced in normal subjects by the injection of highly purified influenza A and B viruses. The reactions reached a maximum at 24–48 hr. and the histological pattern was compatible with a delayed hypersensitivity reaction. There was no close relation between skin test results and circulating antibodies. Twenty-seven subjects were challenged intranasally with attenuated influenza A (H3N2): 5 of 14 skin-test-negative subjects were infected, but none of 13 skin-test-positive subjects.

A prospective serological and clinical study of the epidemics due to the A2/Hong Kong/68 influenza virus was made during the winters 1968–9 and 1969–70 in volunteer subjects in the Royal Air Force. In October 1968 nearly all subjects had haemagglutination inhibiting (HI) antibody to the A2/Singapore/57 virus and more than half had antibody to strains more recently prevalent in Britain. The proportion with HI antibody to A2/Hong Kong/68 increased from 31% in October 1968 (most at low titres) to 44% after the first epidemic and 72% after the second (most at high titres). Serological infection rates were much lower in those who had detectable antibody at the beginning of each winter than in those who did not. Respiratory illnesses coupled with serological evidence of influenza infection during the winter were rare in persons with an initial titre of HI antibody of 1/40 or more. Infection in the first winter conferred complete protection against infection, with or without illness, in the second. In both epidemics about half those with serological evidence of infection had no reported illness.

Strontium selenite A broth incubated at 37° C., and strontium chloride B broth incubated at 43° C., have been found an effective combination for the isolation of Salmonella, Arizona and Edwardsiella from human faeces.

Direct plating on deoxycholate citrate agar was superior to enrichment methods for the isolation of Shigella species.

Strontium selenite A broth was suitable for the isolation of Salmonella and Arizona bacteria at both 37° and 43° C.

Strontium chloride B broth incubated at 43° C. was best for the isolation of Salmonella and Edwardsiella.

Modified bismuth sulphite agar, although superior to D.c. agar for the growth of Salmonella and Arizona bacteria, was unsuitable for Edwardsiella and Shigella species.

A considerable difference was observed in the distribution of Salmonella, Arizona and Edwardsiella serotypes isolated from humans in remote areas, when compared with isolations from more densely populated urban and agricultural centres.

Epidemiological and zoogeographical aspects of host–parasite associations between humans, animals and pathogenic Enterobacteriaceae in Western Australia are discussed.

A survey was conducted in 1971 in healthy reptiles supplied to the Central Animal Laboratory of Nijmegen for experimental animal research. In order to determine which salmonella serotypes occur, and whether there are several serotypes per animal, several strains of each positive sample were typed.

It was found that 160 of 169 samples contained salmonellas or lactose-negative Arizonas or both, and 95 different serotypes were isolated.

Of 127 animals examined individually, 67 were carriers of more than one sero-type, 42 animals having two types, 21 three types and 4 animals four types.

Three enrichment methods were compared. These were tetrathionate broth incubated at 37° C. (T37) and at 43° C. (T43), and selenite broth incubated at 37° C. (SB). All were incubated for 48 hr. before subculture on brilliant-green agar plates. The enrichment methods T37, T43 and SB produced 99, 125 and 123 positive samples respectively, when taken separately. The combinations of T 37 and T43, T37 and SB, and T43 and SB produced 145, 142 and 150 positive samples respectively.

The yield of serotypes in comparable samples showed no difference between the three enrichment methods. With the use of two methods the yield increased by about 38 % compared with one method, and the combination of three methods showed an increase in serotype yield of about 64 % compared with one method. A distinct preference by serotypes for definite enrichment methods was not proved.

Airborne bacteria surveys in nuclear submarines show that the total microbial load was maintained at satisfactorily low levels during prolonged patrols despite factors which were expected to increase this form of pollution.

The isolation rates of Staphylococcus aureus and Neisseria meningitidis from nasal and nasopharyngeal swabs respectively, together with the serum antibody titres to Mycoplasma pneumoniae, before and after patrols suggested that the transmission of these organisms between individuals was not much increased by patrol conditions. The finding of higher numbers of airborne gram-negative rods and bodily contamination by enterobacteria is frequently reported in submersibles but does not appear to cause major outbreaks of illness in nuclear submarine crews.

The direct fluorescent antibody test was assessed for detection of Brucella abortus in bovine abortion material. Br. abortus organisms could be readily detected as characteristic intra-cellular clumps, in smears stained with fluorescent antibody. Counterstaining with Evans Blue was necessary to suppress tissue auto-fluorescence. The method was specific and enabled brucella infection to be differentiated, inter alia, from Q-fever infection.

Typing of Mycobacterium avium strains obtained in a study of endemic tuberculosis in a Wildfowl Reserve permitted the recognition of two separate infected groups. The main infection was in Anatidae and was due to M. avium, type 1; the other was in chickens used for incubation and brooding and the predominance in it of type 2 agreed with normal experience of birds, pigs and cattle in Britain. Many of the strains isolated from the Anatidae were aberrant and methods used to investigate these are described; two of the strains may belong to a new type. Birds which died from other causes, usually trauma, often had subclinical tuberculosis and 5% of the samples of mud and soil examined yielded M. avium.

Of 173 epidemiologically unrelated strains of Escherichia coli isolated from the pericardial sac of chickens that had died from infection with these organisms in England in 1972, approximately 1 year after the introduction of legislation forbidding the routine use of feeds containing ‘therapeutic’ antibiotics, 83·8% were resistant to sulphonamides, 31·2 % to tetracyclines, 20·8% to furazolidone, 18·5% to streptomycin, 2·9% to spectinomycin and 1·2% to ampicillin; none of the strains were resistant to chloramphenicol, neomycin, polymixin, trimethoprim or nalidixic acid. The sulphonamide resistance and possibly some of the resistance to other agents might have been the consequence of sulphonamides being exempted from the legislation. Much of the resistance, with the exception of that to furazolidone, was of the transferable type. Many strains possessed transfer factors in the absence of any known transferable characteristic. Colicine production was twice as common in the pathogenic strains as in a collection of strains isolated from the faeces of healthy chickens; about half of it was transferable.

By means of serology, antibiotic resistance and other markers, it was found that several different kinds of E. coli were usually incriminated in any one outbreak of E. coli infection in broiler chickens. Sometimes the same kinds of E. coli were found in outbreaks in consecutive crops of chickens on the same farm. New kinds, too, appeared to be brought in by replacement chickens.

During a laboratory study of diarrhoea in a large urban area during the years 1953–68, 5319 Sonne dysentery infections in 2620 households and six cases of Flexner dysentery in five households were confirmed. The annual incidence per 10,000 population fluctuated between 2 and 31 with an average of 12.

Shigella sonnei was found in 10% of new cases of diarrhoea investigated. Plural infections were found in 58% of the households studied and 30% of all contacts examined were shown to be infected. Among these contacts the infection rate was higher for children (42%) than adults (20%), and higher for adult females (24%) than males (16%). The duration of infection was under 2 weeks in nearly half the index cases followed up and longer than 2 months in only 3%, Intermittent excretion was observed in 15%. Repeated Sonne dysentery infection and illness was observed after intervals as short as 5 months. Antibiotic sensitivity was recorded after 1955 and colicine typing after 1960. Changes in antibiotic sensitivity were noted. Children of primary-school age were most susceptible to Sonne dysentery, but symptoms in ill cases were as severe in adults as in children. During years of high incidence cases were concentrated within a small number of primary schools.

Sh. sonnei infections were compared with salmonella infections studied concurrently. Sonne dysentery was a winter disease and most cases were under 11 years old, and case-to-case infection was the usual means of spread. Salmonellosis was prevalent in summer and affected nearly as many adults as children, often persons sharing an article of food. It was more prolonged and severe than Sonne dysentery, but less infectious. In all these respects S. typhimurium occupied an intermediate place between Sonne dysentery and ‘other salmonellas’.

The extraction of group A streptococcal antigens by group C phage-associated lysin has been confirmed. In addition to the T antigen the extract contained M-protein, group-specific polysaccharide and mucopeptide antigen which was difficult to remove. This method of extraction of the T antigen was compared with the trypsin method. The latter method was found to be of advantage in giving a pure specific antigen.

An evaluation has been undertaken of the efficiency of laminar-flow ventilation in operating-rooms in which conventional operating-room clothing was used. It has been demonstrated that velocities in the region of 0·3–0·4 m/sec. will give maximum returns for effort in both down-flow and cross-flow systems. At this velocity the laminar-flow system, in terms of airborne bacteria measured at the would site, was about 11 times more effients using horizontal air-flow and 35–90 times more efficient using vertical air-flow than a plenum-ventilated operating room.