A comparison of methods for the isolation of salmonellae from sewage sludge

Methods for the isolation of salmonellae from sewage sludge were compared. Buffered peptone water and lactose broth were compared to determine their efficiencies as preenrichment media and temperature and duration of incubation were also investigated. In addition five enrichment and five plating media were compared together with the effects of multiple plating of enrichment broths. Buffered peptone water incubated at 43 degrees C for 24 h was shown to be the pre-enrichment method of choice with enrichment in the RB 10 form of Rappaport's broth incubated at 43 degrees C for 48 h and plating at 24 and 48 h onto brilliant green agar containing sulphamandelate supplement and Hynes' modification of desoxycholate citrate agar. Of the 100 samples used in the study. 96 were found to be positive for salmonella by at least one of the procedures used. A total of 15 Salmonella serotypes were isolated. Salmonella virchow being the most common.