Inhibition of Proteus Swarming by the Metabolic Products of Serratia Marcescens
Proteus vulgaris and Proteus mirabilis, members of the family Enterobacteriaceae, exhibit the phenomenon of swarming on moist agar media. Swarming is a cyclic pattern of active motility and stationary growth away from a point of inoculation giving rise to concentric rings of growth on the agar surface (Fig. 1). On media that is exceptionally moist, the concentric rings may be absent and swarming may only appear as a thin film of growth over the entire surface. | The presence of swarming species of Proteus in mixed culture with other bacteria has always presented a problem of isolating the latter in clinical specimens. Many methods have been devised for preventing the swarming of Proteus species with varying degrees of success. For example, an increase in the agar concentration of solid media to 6% (17), or growth on a salt-free medium (40), will inhibit swarming. The addition of a number of chemical agents to the median, such as sulfonamides, surface active agents, or narcotic drugs, to mention only a few, will inhibit swarming (32). | Halkias and Fulton (14) observed that pigmented strains of Serratia marcescens grown in mixed culture with Proteus species exerted an inhibitory effect on swarming. The purpose of this research is to determine what effect the pigment, prodigies in, and the other metabolic products of Serratia marcescens have on Proteus swarming.
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