Some aspects of the epidemiology of equine salmonellosis.

A survey of 2 horse populations was done to detect the number of asymptomatic faecal excretors of Salmonella sp. 1201 faecal samples from 250 horses hospitalised at the University of Sydney were cultured. Three serotypes, S. typhimurium (4 horses), S. anatum (2) and S. tennessee (1) were isolated from 7 horses (2.8%). None was detected in 75 mares similarly examined at a thoroughbred stud farm. In retrospect, S. typhimurium was also the most common (70%) of the 19 serotypes recovered from 171 horses with clinical salmonellosis seen at Camden, 1969 to 1986. Forty cases occurring since 1983 were reviewed in detail; the mortality rate was high (60%) and an increased proportion was due to S. bovis-morbificans. Five horses developed salmonellosis while hospitalised and it was usually impossible to be certain whether these cases developed from the carrier state into overt disease or resulted from infections acquired in hospital.

A small episode of single quarter coliform infections in lactating dairy cows kept at pasture.

For a period of 150 days, an Escherichia coli infection in a single quarter of the udder of 13 cows occurred on average every 9 days, in a herd of 120 cows kept at pasture under temperate environmental conditions. Most cases were clinically mild, affecting cows in lactations 1 to 10 and at all stages of lactation; none were evident at calving. Samples of secretion from infected quarters sometimes had few demonstrable organisms. Eleven different serotypes in 8 (0) groups were recovered; one isolate was multiply resistant to antibiotics and one infection persisted for 120 days. A precise explanation for this episodic exacerbation of the new infection rate was not established, but probable contributing factors were recognised.

A reagent strip for measuring the specific gravity of urine.

A solid-phase reagent for determination of urinary specific gravity (relative density) is described. This reagent strip, similar to others in the "N-Multistix" series (Ames), contains a polyacid whose acidity is sensitive to the ionic concentration in the urine in which it is immersed. As the acidity of the polyacid changes, pH changes are detected by a pH indicator within the reagent strip. In comparison studies, 84.4% of relative densities as measured with these reagent strips were within 0.005 of the corresponding results with a total-solids meter, and 89.9% were within 0.005 of the corresponding urinometer results. Adding a correction of +0.005 to the reagent-strip results for urines with high pH increased the percentage of results within 0.005 of the comparison method to 90.7% (TS meter) and 92.9% (urinometer). Lot-to-lot variability and reader-to-reader variability were both low. Reagent strip results are not affected by glucose, may be increased by albumin, and correlate with urea concentrations.

Mesothelial cells of peritoneal fluid.

Cells in the peritoneal fluid from 159 horses were examined in Giemsa stained preparations using light microscopy. Normal mesothelial cells showed an oval nucleus with finely reticular chromatin and pale blue cytoplasm. Activated mesothelial cells occurred in fluids derived from mesothelium under acute or subacute, non-septic stimulus and were remarkable for their pleomorphism and intense basophilia which may mimic neoplasia. Transformed mesothelial cells seen in chronic inflammatory fluids were sometimes phagocytic and showed conspicuous cytoplasmic vacuolation.

Reference values for equine peritoneal fluid.

Twenty horses, aged one to 17 years (mean age 6 years), presented for elective destruction and subsequently found at autopsy to have no significant peritoneal alterations, were used to determine a variety of reference values for peritoneal fluid. Samples were collected ante mortem or within 1 h post mortem. Each cavity contained 100 to 300 ml of usually clear, pale yellow fluid which in a clinical refractometer showed a mean specific gravity 1.010 (range 1.0081-1.0116) and mean (+/- standard deviation) total protein 7.7 +/- 3.6 g/litre. The mean total nucleated cell count (+/- sd) was 4.33 +/- 2.5 x 10(9)/litre (range 1.5-10.1 x 10(9)/litre) and, proportionally, polymorphonuclear leucocytes averaged 45.2 per cent, mononuclear phagocytes 47 per cent, lymphocytes 7.8 per cent, eosinophils 0.7 per cent and basophils and mast cells zero. Eosinophils were not usually seen but 6 samples had 1 to 5 per cent. The peritoneal fluid chemical profile (mean +/- sd) was: Aspartate aminotransferase (AST) 118.9 +/- 46.9 iu/litre; alkaline phosphatase (AP) 56.0 +/- 52.7 iu/litre; lactate dehydrogenase (LDH) 143.0 +/- 106.1 iu/litre; total bilirubin (TB) 8.0 +/- 6.2 mumol/litre; total protein (TP) (biuret method) 14.2 +/- 6.8 g/litre; urea nitrogen (BUN) 6.1 +/- 1.1 mmol/litre; glucose 7.7 +/- 1.8 mmol/litre; inorganic phosphate (IP) 1.4 +/- 0.5 mmol/litre; calcium 2.0 +/- 0.2 mmol/litre. TP, BUN, glucose and IP were closely correlated with levels in paired serum samples.

Surcrose uptake by Neisseria denitrificans.

Neisseria dentrificans possesses an inducible sucrose-uptake system. Sucrose is transported as the free sugar and is rapidly converted into polymerized material. Uptake is inhibited by glucose, cyanide, uncouplers of oxidative phosphorylation, and sulfydryl reagents. Glutamate serves as an energy source for uptake. The importance of this phenomenon in the oral environment is discussed.

Salmonellosis in calves due to lactose fermenting Salmonella typhimurium.

A lactose fermenting strain of Salmonella typhimurium was isolated from two calves which died during an outbreak of acute enteritis. The organism was biochemically typical in all other respects. In one calf, uncomplicated by treatment before death, the autopsy findings were those of a severe fibrinous enteritis which was reproduced in another calf dosed orally with culture. Attention is drawn to scattered reports of lactose fermenting salmonelle causing morbidity and mortality in calves and man.