Abstract
In addition to inadequate understanding of swarming motility and virulence of Proteus, there is paucity of information on the relative effectiveness of the various anti-swarm agents. The anti-swarming effects of urea, sodium dodecylsulphate (SDS) and trihydroxymethylglycine (Tris) on 40 clinical isolates of Proteus Spp. were comparatively investigated and plasmids associated with swarming were characterized. The three substances elicited a comparable concentration-dependent anti-swarming property at 0.25 – 1.25% on nutrient agar. Anti-swarm agents displayed heterogeneity in their ability to cause significant decreases in the expression of virulence factors. Swarm motility was further found to be strongly associated with the expression of virulence factors in these strains. Of the Proteus strains tested, 32 were found to harbour 1 – 4 plasmids of size ranging from 6.0 – 33.5 kb. Plasmid curing resulted in loss of swarming in 65.6% of these strains. In order to reduce the risk of infection with virulent Proteus strains, the laboratory use of urea and SDS is suggested. Key words: Proteus, swarming, urea, SDS, Tris.
Highlights
Proteus species contribute greatly to neonatal mortality among Africans with urinary tract infections and are a leading cause of bacteruria associated pregnancy loss worldwide (Orrett, 1999; Cutner et al, 1992)
The effects of urea, Tris and sodium dodecylsulphate (SDS) on swarm motility, extracellular protease and urease activity, cellular RNA and carbohydrate content among the 40 Proteus strains tested are presented in Figures 1 - 5
A surface dependent coordinated multicellular behaviour has been established to be the basis for colonization and expression of virulence factors by pathogenic organisms including Proteus
Summary
Proteus species contribute greatly to neonatal mortality among Africans with urinary tract infections and are a leading cause of bacteruria associated pregnancy loss worldwide (Orrett, 1999; Cutner et al, 1992). VanAsten and Gaastra (1999) reported difficulties in identifying P. aeruginosa and Streptoccocus G in mixed cultures involving Proteus. Cases of re-current bacteruria are very common in developing countries in particular and this have been blamed on culture diagnostic inappropriateness caused by swarming motility of Proteus and related organisms (Williams and Schwartzhoff, 1978; Harshey, 1994). This scenario may contribute to spread of multidrug resistance strains and treatment failures of polymicromicrobial infections. Efforts to annul the effects of swarming and enhance diagnosis through culturing in minimal media often fail to identify copathogens with Proteus that are fastidious or require extra nutrient supplements for growth (Reynolds and Penn, 1994)
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