INHIBITION OF SWARMING BY UREA AND ITS DIAGNOSTIC IMPLICATIONS AMONG UROPATHOGENIC PROTEUS SPECIES FROM LAGOS, NIGERIA

Abstract

The anti-swarming property of urea and effects on antibiotic susceptibility among 52 uropathogenic Proteus strains from Lagos, Nigeria were investigated. Urea caused a reduction in swarming and number of swarmed cells at 0.5% (n = 42, DOCZ = 15.5mm), 0.75% (n= 24, DOCZ = 10.7mm), 1% (n = 17, DOCZ = 3.4mm) and 1.25% (n = 8, DOCZ = 1.7mm).  Compared to DOCZ obtained at 0.5% urea, the further reduction in DOCZ at other urea concentrations was found to be significant (p < 0.05).  Urea at less than 0.75% allowed identification of E. coli, K. pneumoniae and S. saprophyticus in mixed cultures containing Proteus spp, while colonies of Pseudomonas aeruginosa were distinctly identified at 1% urea with swarming restrained at 1.25% urea.  At 1.25% urea, antibiotic susceptibility testing by agar diffusion method revealed significant increase and decrease in the number of Proteus strains that showed resistance to amoxicillin and nitrofurantoin. Compared with the control, significant increases in the MICs of gentamicin or nitrofurantoin and streptomycin were found at $ 0.5% and $ 0.75% urea respectively (p<0.05). The identification of extended spectrum beta lactamases (ESBL) producing strains were unaffected by urea.  This study has demonstrated urea induced swarming inhibition of uropathogenic Proteus in vitro.  However, results suggest the use of urea with great caution in diagnostic practices for optimal clinical and public health benefits in Nigeria.


Keywords: Antibiotic susceptibility, anti-swarming, urea, uropathogenic proteus, Nigeria, DOCZ = Diameter of outermost colony zone mean value


(Af J Clinical & Exp Microbiology: 2003 4(2): 18-28)