Colonization of the caeca of newly hatched chicks by Salmonella typhimurium was prevented by oral administration of a mixture of cultures comprising 48 different bacterial strains originating from an adult bird known to be free from salmonellas. The treatment conferred protection to the same degree as that obtained previously with a suspension of adult caecal contents or an undefined anaerobic culture from the same source and was demonstrated in four separate laboratory trials.

Examination of the caecal microflora of chicks one day after being given the protective treatment showed that the presence of high levels of lactobacilli and Bacteroides spp. which are not found usually at two days of age in chicks produced under commercial conditions was indicative of the successful establishment of an adult-type microflora.

Although the usual method of administering the protective organisms was to dose the chicks directly into the crop, it was also found possible to incorporate the organisms in the drinking water given to the birds at dilutions up to one in five, the maximum tested.

When chicks were given the bacterial mixture via the crop and fed on a diet containing 10 mg kg−1 nitrovin and 100 mg kg−1 monensin, the bacteroides failed to establish in the caeca and the birds were not protected against salmonella colonization. However, when the bacterial cultures were incorporated in the drinking water and the chicks given the same feed, normal protection was obtained; possible reasons for these observations are discussed.

Of 120 specimens of garden fertilizers of animal origin purchased in retail shops, 40 (33·3%) were found to be contaminated with salmonella organisms. Untreated bone meal (53·1%) was the most heavily contaminated but 25% of specimens of this product classed as heat-treated or sterilized were positive. In all, 32 serotypes were identified.

A study of the ability of 49 strains of FMD virus to replicate in BHK-21 monolayer cells maintained under a standard agar overlay containing 5·2 mM guanidine hydrochloride and to withstand heat inactivation at 54°C for 1 h showed that strains belonging to serotypes C, O and Asia 1 were generally more resistant to guanidine and heat stable than the SAT 1, 2 and 3 serotypes. The type A viruses as a whole occupied an intermediate position between these two groups.

In vitro passage in BHK-21 cells influenced the guanidine sensitivity of 3(O, C and SAT 3) of the 7 FMD serotypes suggesting that this is not a stable genetic marker. Heat stability of the FMD viruses, however, did not change on passage, suggesting that this is a stable characteristic inherent in any homogeneous FMD virus population.

One hundred and forty-eight sera from 101 cases of acute postnatal rubella were examined by the radial haemolysis (RH) technique currently recommended by the Public Health Laboratory Service of the United Kingdom. In 75 cases the date of onset of rash was known. No sera were RH positive until the third day after the onset of rash and one serum was still negative at 9 days. By 10 days all sera gave a zone of at least 10 mm. The antibody response detected by RH appears later than that detected by haemagglutination inhibition (HI). Thirty-nine of the 101 cases could be diagnosed by seroconversion or a significant rise in titre using the HI test (diagnosis of the remainder depending upon rubella-specific IgM tests). Using the RH test this figure rises to 48 but in ten of these cases reliance on RH would have meant a delay in diagnosis. The results also indicate that many more sera would need to be tested for rubella-specific IgM if the RH test was used instead of the HI test for evaluating possible cases and contacts of rubella.

Epidemiological data accompanying reports of more than 1000 outbreaks of food poisoning have been studied to determine the factors which most frequently contributed to the outbreaks. Preparation of food in advance of needs combined with improper storage and inadequate cooking, cooling and reheating were the most common factors. Infected food handlers did not play a significant role except in instances of S. aureus food poisoning.

The aim of the study was first, to determine the prevalence of Neisseria meningitidis among the family members living with patients suffering from meningococcal infections, and second, to ascertain the distribution among these family members of strains epidemiologically related to those isolated from patients.

Forty-two family groups were studied and 135 nasopharyngeal samples were taken from family members living with patients.

Twenty family groups were found to contain meningococcal carriers, and of these 20, 13 contained a carrier of the strain that caused the infection (65%). Among the family members who were carriers, the mother and father most frequently yielded the strain which caused the illness.

The serotypes most frequently encountered both in patients and carriers were 2 and 8, as well as nontypable strains.

The polyacrylamide gel electrophoretic patterns (PAGE) most frequently found were II and IV. A notable feature of the study is the high resistance of the strains to sulphadiazine, since more than 90% of the strains found in patients and more than 75% of those from carriers possessed a minimum inhibitory concentration greater than or equal to 10μg/ml.

Enterotoxin production by strains of Staphylococcus aureus isolated from clinical specimens of human and animal origin and from healthy human carriers was investigated. All nine patients admitted to hospital with symptoms of toxic shock syndrome (TSS) yielded enterotoxin-producing strains of S. aureus. Eight of these produced staphylococcal enterotoxin F (SEF). A significantly smaller proportion of strains (42% of 50 strains tested) isolated from other clinical specimens of hospitalized patients produced SEF. Production of SEF by strains isolated from clinical specimens of animal origin (48 strains) was not observed. Twenty-nine per cent of 24 S. aureus strains isolated from noses of hospital staff produced SEF. This result was not significantly different from that obtained from strains isolated from clinical specimens other than TSS. A similar percentage of strains isolated from healthy human carriers outside hospital produced SEF (25% of 24 strains tested).

The results indicated that enterotoxin production, especially that of SEF. is associated with S. aureus isolated from patients suspected of TSS. There was no indication of an association between S. aureus isolated from other staphylococcal infections and SEF production.

All strains were phage typed and 79%, of the strains belonging to the international phage-group I produced SEF. All strains lysed by phage 187 were found to produce SEF.

Chlorine dioxide, bromine chloride and iodine were compared with chlorine as virucidal agents. Under optimal conditions all disinfectants were effective at low concentrations, but each disinfectant responded differently to acidity and alkalinity. Disinfection by chlorine was impaired by the presence of ammonia, but the other disinfectants retained much of their potency. Disinfection of poliovirus by iodine resulted in structural changes in the virions as seen by electron microscopy, but the other disinfectants were able to inactivate poliovirus without causing any apparent structural changes.

A single-tube confirmatory test that allows a result to be obtained in 4 h has been developed from the single-tube confirmatory test recommended by the Joint Committee of the Public Health Laboratory Service and the Standing Committee of Analysts (PHLS/SCA, 1980). A variety of river, lake and reservoir samples were examined for the presence of E. coli using either most probable number (MPN) or membrane filtration (MF) technique, and the PHLS/SCA recommended confirmatory medium (LTMB) was evaluated against traditional methods. To improve the performance of LTMB, the medium was modified and this modified medium when used in 0·1 ml volumes and incubated for 4 h at 44°C provided 99% agreement with traditional methods.

Nineteen of 98 samples of mud or sand taken from the Mersey estuary in 1981 contained Clostridium botulinum type C, the organism almost always responsible for botulism in water birds. In the Dungeon and Score Bank areas, where many dead and dying birds were found during the period September–December 1979, almost half the samples contained type C. Most of the positive samples were essentially muddy rather than sandy. The findings do not prove that botulism contributed to the 1979 mortality but are nonetheless thought-provoking, particularly because type C – unlike type B – is by no means ubiquitous in Britain. Type B was present in 12·2% of samples from the Mersey estuary.

Levels of maternally transferred antibodies against the surface antigen of the A/Texas/1/77 strain of influenza virus showed the expected decline during infancy when measured by complement fixation (CF). However, this decline was not observed when these antibodies were measured by haemagglutination-inhibition (HI). It has been postulated that this discrepancy is due to the acquisition, in the early days of life, of non-specific serum factors which increase the HI activity of sera. The levels of these factors were determined indirectly by calculating HI: CF ratios and it was shown that the factors are rapidly acquired by children between the fifth and twentieth week of life.

Inbred strains of mice varying in susceptibility to intraperitoneal (i. p.) inoculation of HSV-1 were tested by inoculating 105 p.f.u. of the SC 16 strain into the ear pinna. Increase in ear thickness was less in resistant than in susceptible strains. In the resistant C57BL/6 strain, local replication of virus, spread to cervical ganglia and development of latent infections of the ganglia were all less than in susceptible DBA/2 mice; there was also less cellular infiltration of the inoculation site. Like resistance to i.p. inoculation, resistance to ear inoculation appears to be inherited as a dominant characteristic. The test provides a non-lethal method of distinguishing between resistance and susceptibility of inbred strains of mice to HSV-1 and may also be useful in defining resistance factors.

A limited assessment of immunity to diphtheria revealed that only 44·8 % of adults had protective levels (> 0·01 U/ml) of diphtheria antitoxin in their sera. In the light of this information, it was decided to assess the suitability of Adult-type Tetanus-Diphtheria Vaccine as a replacement for Adsorbed Tetanus Vaccine in occupational health schemes. A comparative study of these vaccines showed that a single dose of each produced an equivalent rate and level of tetanus antitoxin responses. Adult-type Td Vaccine elicited more than fourfold increases of diphtheria antitoxin in 76 % of vaccinees. No statistically significant differences were observed in the clinical reactivity of the vaccines under test. However, the combined vaccine caused a slightly higher incidence of local reactions (pain, redness and swelling) while recipients of Adsorbed Tetanus Vaccine more frequently experienced pain.

There are few data about the distribution of neutralizing antibodies (NA) against adenovirus types in the Italian population, especially the high-numbered ones. We tested the sera from 453 children and 51 young adults to evaluate NA against adenovirus prototypes 1–33. Using the microneutralization test, 338 (74·6%) of the children's sera were positive for at least one adenovirus type. Antibody to type 2 was the most frequently detected followed, in descending order, by antibody to types 5, 1 and 3. All these types are known to be associated with disease but antibody to type 7, a type also associated with disease, was less frequent than that to other serotypes such as 18 and 31, the pathogenicity of which in man is not clearly established. The antibody positivity rate rose with age for the more frequent types while it did not vary for the less frequent ones. The number of sera with NA against more than one adenovirus type increased with age. With regard to types 1–8, we found that their frequencies in Italy were similar to those found in the U.S.A.

An epidemiological study on Campylobacter jejuni enterocolitis was performed in an urban Swedish community. The study included 55 patients gathered during a six-month period. Forty-one of the 55 patients (75%) were infected outside Sweden. Campylobacter enterocolitis was rare among children within the country. Patients infected in Sweden had eaten chicken significantly more often than a corresponding control group. Seven out of nine chicken consuming campylobacter patients also had prepared the fresh chicken alone, and none of their family members became ill. Thus the preparation of food contaminated with Campylobacter seems to elevate the risk for contracting the disease. Sick household pets transmitted the campylobacter infection to two patients. Forty-six of the patients had a total of 85 close household members. Three definite secondary cases were found. There was no evidence of transmission of Campylobacter by food prepared by two cooks who were working while still being asymptomatic excreters. Clinical reinfection with Campylobacter was observed in one patient. No patients became long-term carriers of Campylobacter.

So-called LC strains of Mycoplasma mycoides subsp. mycoides and, where appropriate, SC strains, were examined, together with M. mycoides subsp. capri strains, by growth, fermentation, and antibiotic-sensitivity tests.

Growth curves in BVF-OS medium showed that, from the 6th until at least the 19th day of incubation, strain Mankefår 2833 had a viable count strikingly higher than that of any other LC strain. Its robust growth properties may explain its ability – unusual among LC strains – to produce mycoplasmaemia readily in mice. Strain 143–A66 Conn, also shown by earlier experiments in mice to possess unusual properties, lost viability more rapidly than any other LC strain between the 13th and 19th days of incubation. The viable count of a subsp. capri strain was considerably lower than that of any LC strain for much of the period between days 6 and 19.

In fermentation tests with 27 substrates and sensitivity tests with 11 antibiotics the strains gave results that, in all but the following respects, were uniform. Sorbitol was fermented to varying degrees by all the LC and subsp. capri strains tested but was unaffected by the SC strains. The LC and subsp. capri strains were in general more resistant than the SC strains to streptomycin. The growth of the LC strains, much more than that of the other strains, was greatly stimulated by the presence of fermentable substrate.

Spleen cells from uninfected CBA mice are more cytotoxic for Sendai virus-infected L929 cells than for uninfected cells and the lymphocytes responsible have the properties of NK cells. Preincubation of spleen cells with culture supernatants from Sendai virus-infected L929 cells increases the cytotoxicity for uninfected target cells. This increase in cytotoxicity can also be produced by pretreatment with purified mouse interferon. The enhancing effect of both the infected culture supernatants and purified interferon can be neutralized with anti-interferon serum. It is concluded that the preferential killing of Sendai virus-infected L929 cells by NK cells is dependent on the induction of interferon and that interferon will increase NK cell cytotoxicity for uninfected target cells.

From October 1977 to May 1980, 243 stools collected in sedentary and semi-nomadic populations of the Ahaggar (Algerian Sahara) were examined using immunoelectronmicroscopy and tissue culture inoculation. Immunoelectron-microscopy revealed the presence of rotaviruses in 8, coronaviruses in 26, adenoviruses in 5 and small round viruses in 4. Enteroviruses were isolated in tissue culture from 24 stools.

Rotaviruses were present in the Ahaggar but were associated with little acute enteric disease. The high frequency of coronaviruses both in gastroenteritis patients and in patients without disease was surprising. The prevalence of enteroviruses in this hyperarid zone was similar to or higher than that found in noticeably more humid countries.

Further systematic bacterial, viral and parasitic examinations are required to clarify the role of the above viruses in the aetiology of gastroenteritis in this region.

Immunoelectrophoresis of ultrasonically disrupted Haemophilus equigenitalis (contagious equine metritis organism) cells against rabbit and equine antisera disclosed at least 11 precipitating antigens. Two of these, a polysaccharide and a lipopolysaccharide–protein complex, were of high molecular weight and located on the cell surface. The remaining antigens were intracellular and were small- to medium-sized proteins.

The surface antigens were the most significant in relation to the serological response in infected horses. They also reacted with sera from apparently healthy cattle, but the reason for this was not determined. No serological cross-reaction between H. equigenitalis and species of Achromobacter and Moraxella was detected.