Further studies on the influence of variations in the enrichment method for the detection of salmonellae

Faeces and mesenteric lymph nodes of pigs were examined for salmonellae. Two jars of Müller-Kauffmann's tetrathionate broth and two jars of Osborn-Stoke's selenite — brilliant green medium were inoculated. After both 24 hr and 72 hr incubation periods subinoculations on Kauffmann's brilliant green — phenol red medium were made in duplicate from each jar.Planting after 24 hr and 72 hr incubation periods resulted in an increase in the number of positive results, whereas plating in duplicate after 24 hr failed to do so.Plating after the 24 hr incubation period from two different jars containing the same enrichment medium resulted in an increase in the number of positive results equivalent to that obtained by plating after the 72 hr incubation period from one jar.With faeces, both enrichment media gave approximately equal numbers of positive results. With lymph nodes, the selenite — brilliant green medium gave more positive results than were obtained with Müller-Kauffmann's tetrathionate broth.