Growth of Salmonella choleraesuis subspecies diarizonae serovar 61:k:1,5,(7) in broth and fresh mutton

Three serovars of Salmonella choleraesuis (IIIb 61:k:1,5,(7), Enteritidis and Dublin) were grown in broths of pH 5.5 and 6.2 and incubated at 4, 6, 8 or 12°C. Growth in the broth, measured by means of an increase of absorbance, was not observed below 8°C. At 8 and 12°C, the maximum growth rate (μmax), lag period and maximum absorbance level (maxabs) varied according to serovar and pH. In general, serovar IIIb 61:k:1,5,(7) and serovar Enteritidis grew better than serovar Dublin. The effect of pH on lag period, seen for serovar IIIb 61:k:1,5,(7) and serovar Enteritidis at 8°C, was absent at 12°C, while the effect of pH regarding the μmax and the maxabs was observed also at 12°C. Furthermore, the growth serovar IIIb 61:k:1,5,(7) in normal and dark, firm and dry meat at 8°C with ambient air in competition with the natural microbial flora was tested in minced meat and chops. Slow growth of serovar IIIb 61:k:1,5,(7) was observed in minced meat. The low virulence and the ordinary growth capabilities indicate that serovar IIIb 61:k:1,5,(7) will probably not represent a serious hazard to the public health.