The effect of natural Corynebacterium pseudotuberculosis infection on wool production and quality in sheep was examined in light of evidence that artificial C pseudotuberculosis infection causes wool production loss. A toxin ELISA was used to identify sheep that had been infected with C pseudotuberculosis. Greasy and clean fleece weights and fibre diameter were compared in infected and uninfected sheep. C pseudotuberculosis infection caused a 3.8 to 4.8% decrease in greasy wool production and a 4.1 to 6.6% decrease in clean wool production. C pseudotuberculosis infection did not affect fibre diameter. The effects of caseous lymphadenitis (the disease caused by C pseudotuberculosis infection) cause an annual loss of about $17 million in wool production to the Australian wool industry.

SUMMARY The decrease in the prevalence of Corynebacterium pseudotuberculosis after two generations of vaccination against the disease it causes, was used to estimate the rate of control of caseous lymphadenitis (CLA). Three groups of 150 sheep, of which 50 in each group were artificially infected with C pseudotuberculosis and 100 in each group were uninfected sheep, were run separately for 40 months and shorn 5 times to promote the spread of CLA. One lot of 50 infected sheep and 2 lots of 100 uninfected sheep were vaccinated against CLA. The rate of spread of CLA was recorded. Sheep vaccinated against CLA and naturally exposed to infection had a 74% lower infection rate than unvaccinated sheep. Sheep vaccinated against CLA and exposed to only vaccinated infected sheep had a 97% lower infection rate. Unvaccinated sheep had a 76% infection rate, with 77% of the transmission occurring at the 4th and 5th shearings, without any discharging CLA abscesses being observed. This study supports the view that in Australian wool producing flocks, CLA spreads mainly from sheep with discharging lung abscesses to sheep with shearing cuts. Vaccinated sheep infected with CLA have 96% fewer lung abscesses compared with unvaccinated infected sheep and are therefore less likely to spread this disease to other sheep.

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Aerobic Plate Count (APC) and spiral plate (Spiral) methods using both manual counting (MC) and laser counting (LC) procedures were compared for pure bacterial, yeast, and mold cultures and raw milk samples. All four combinations of methods (APC-MC, APC-LC, Spiral-MC, and Spiral-LC) gave similar log,, counts of studied pure microbial cultures, producing results that were not different for the purposes of practical microbiology. With bacterial and yeast cultures, counts differed by less than half a logarithmic cycle (the range of di3erence = -0.26 to + 0.42). the range of difference being -0.03 to + 0.62 for Aspergillus flavus and Penicillium camemberti molds. An exception was noticed with Rhizopus oligosporus mold when plates were read by laser due to large (10-15 mm) colony size. The difference between the readings made manually and by laser colony scanner was about one logarithmic cycle with both APC and Spiral methods.Statistical analyses of the manually read results of bacterial and Saccharomyces cerevisiae spiral plates showed no differences at the 0.05 level of significance between the readings made by four or jive persons.For raw milk samples, Spiral-MC and Spiral-LC methods gave higher microbial numbers than APC-MC (63% of samples) and APC-LC (54% of samples) at 0.05 level of significance (p

Enumeration of yeast and molds from 39 food samples, including 6 dairy products, 2 meat products, 5 cereal products, 9,fruits. 4 vegetables, 6 beverages, 4 spices, and 3 condiments on Trypan blue (at 1: 10,000 dilution) in potato dextrose agar (Trypan blue agar) was compared with Congo red (at 25:1,000,000 dilution) in potato dextrose agar (Congo red agar) using the hydrophobic gridmembrane Jilter (HGMF) technique of the ISO-GRID system. Yeast and mold grew well on both Trypan blue agar and Congo red agar, producing blue and red colonies, respectively, in the ISO-GRID system, when examined in incandescent light. However, not all yeast and mold colonies grown on Congo red agar jluoresced under ultraviolet (UV) light (a recommended observation procedure). Thus, results indicated that Trypan blue agar observed in incandescent tight is more convenient to use for enumerating yeast and mold in food samples.