- Volume 4, Issue 3, 1971

Colostrum-deprived and normally suckled piglets from normal sows and from sows immunised with an extract of Escherichia coli O138:K81(B) were challenged with the same endotoxic extract preparation by the dermal, intravenous and oral routes. Reactions were more severe in piglets from immunised sows, and lesions were similar to those seen in field outbreaks of E. coli disease. It is postulated that such lesions may be immunological in origin, and that anaphylactic shock may be important in the pathogenesis of E. coli disease in baby piglets.

Liquid-elution counts in a non-ionic surfactant and imprint replicate counts with velvet pads were used to investigate the changes in total bacterial and colony counts on normal skin surfaces after bathing with water, soap, or detergent. The experiments revealed that the total bacterial count on several skin sites was reduced soon after washing, returning in 24 hr to the pre-wash numbers. In contrast, the colonial count from the same sites increased considerably after washing, again returning to the pre-wash count.

An explanation is offered that both kinds of counts were sampled from extremely large aggregates of bacteria on the skin surface, and that these aggregates could be segregated into very much smaller viable units, each still capable of originating individual colonies by either counting method. It is suggested that the extent of separation depended on the mechanical processes of washing, the presence of surface-active agents in the washing water, and the use of a non-ionic surfactant in the sampling and subsequent counting procedure.

Forty strains of enteric bacilli were studied in detail. Biochemically the organisms form a homogeneous group belonging to the family Enterobacteriaceae, but they do not fit into any of the recognised groups. The following pattern of biochemical reactions was recorded. The strains produced indole, utilised citrate and malonate, and decarboxylated ornithine. They failed to produce hydrogen sulphide on TS1, to deaminate phenylalanine or to decarboxylate lysine. The Voges-Proskauer reaction was negative. Acid was produced from adonitol, arabinose, maltose, mannitol, rhamnose and sorbitol in 2 days. Lactose fermentation was delayed. Acid was not produced from raffinose. Preliminary serological studies showed no cross-reactions between these strains and other members of the Enterobacteriaceae. It is felt that this group should be assigned to a new species in the genus Citrobacter.

In-vitro killing of Moraxella nonliquefaciens by phagocytes in homologous serum systems of the guinea-pig was decreased in pyridoxine deficiency. The decreased rate of intracellular killing was correlated with a decrease in histochemically detectable myeloperoxidase.

Anaerobic sarcinae were quantitatively isolated from suspensions of faeces heated at 70°C for 10 min. by plating on meat infusion agar containing lactose, neutral red and egg-yolk and incubating anaerobically at 37°C. Sarcina ventriculi was found in numbers up to 108 per g in faeces from 75 out of 106 healthy human adults living on vegetarian diets, but the organism occurred in the faeces of only 2 out of 123 people living on diets containing animal products. The identification and distribution of the organism are discussed and it is concluded that diet influences the colonisation of sarcinae in the human intestine.

A series of complex immunological changes occur in the lungs of mice infected with Sendai virus. Early in the infection a rapid increase occurs in the number of immunoglobulin-containing cells in the vicinity of infected mucosal cells. Qualitative and quantitative changes occur in the immunoglobulins and other serum proteins in the bronchial secretions at the time of the inflammatory response. High immunoglobulin levels in the bronchial secretions persist long after the inflammatory changes have subsided. The concentrations of detectable specific antibody do not increase until after the commencement of the viral eradication process.

The possible significance of these changes in the termination of primary virus infections is discussed.

The faecal excretion rate of salmonellae in migratory wild ducks is higher than previous studies would indicate. Examination of 477 duck droppings during the winters of 1968/69 and 1969/70 gave isolation rates of just over 4 per cent. The commonest serotype was S. typhimurium; seven different phage-types were found, 2a being the most frequent.

Bacteriological examination of the urine is often rendered useless by overgrowth of organisms, which occurs while the specimen is in transit from clinic to laboratory. A delay of 4 hr at room temperature is often sufficient to produce a 100-fold increase in the viable bacterial count. It is shown that this overgrowth can be prevented by adding to the freshly collected urine a mixed solution of NaCl and polyvinylpyrrolidone to give final concentrations of 9.0 per cent. NaCl and 1.0 per cent. PVP. By this means it is possible to perform quantitative bacteriological tests on mid-stream specimens that have been delayed in transit for 24 hr or longer.

A comparison of Hoyle’s medium and Billings’ modification of Tinsdale’s medium was made. Hoyle’s medium was significantly better for the primary isolation of Corynebacterium diphtheriae from swabs. The only advantage of Tinsdale’s medium was that it could be used by untrained people, whereas the use of Hoyle’s medium required experience. The formation of a halo on Tinsdale’s medium is recommended as a specific confirmatory test for the identification of C. diphtheriae and C. ulcerans.

A species of Coprinus, a widely distributed genus of the toadstool group of fungi, caused endocarditis of the normal aortic valve of a patient who had undergone mitral valve replacement. Human infection by this genus has not hitherto been reported.

Lysozyme production by members of the Micrococeaceae was tested for by a plate method. All coagulase-positive staphylococci and a number of other staphylococci and micrococci produced lysozyme.

Many coagulase-negative staphylococci and micrococci from infections of the urinary tract produced lysozyme, particularly those belonging to Micrococcus subgroup 3 in Baird-Parker’s scheme, but lysozyme production was more frequent in urinary than in skin strains, not only in this subgroup but in several other subgroups of staphylococci and micrococci.

Coagulase-negative staphylococci that colonised internal artificial prostheses rarely produced lysozyme. It is suggested that cocci that cause indolent colonisation of internal prostheses are not pathogenic in the conventional sense.

A new medium is described for the selection and identification of Pseudomonas aeruginosa. It contains glycerol, mannitol, acetamide, cetrimide, a trace of peptone and phenol red. On this medium incubated at 42°C, nearly all cultures of Ps. aeruginosa, but only very few other bacteria, form colonies or areas of growth surrounded by a red zone. The medium may be used either for the direct enumeration of Ps. aeruginosa or to establish the presence of this organism in liquid enrichment cultures.