Hemagglutinin, Urease, and Hemolysin Production by Proteus mirabilis from Clinical Sources

Abstract

Proteus mirabilis, a common cause of urinary tract infection, can lead to serious complications including pyelonephritis. Adherence factors, urease, and hemolysin may be virulence determinants. These factors were compared for bacteria cultured from 16 patients with acute pyelonephritis and 35 with catheter-associated bacteriuria and for 20 fecal isolates. Pyelonephritis isolates were more likely (P less than .05) to express the mannose-resistant/Proteus-like (MR/P) hemagglutinin in the absence of mannose-resistant/Klebsiella-like (MR/K) hemagglutinin than were catheter-associated or fecal isolates. Pyelonephritis isolates produced urease activity of 63 +/- 27 (mean +/- SD) mumol of NH3/min/mg of protein, not significantly different from catheter-associated or fecal isolates. Hybridization of Southern blots of P. mirabilis chromosomal DNA with two urease gene probes demonstrated that urease gene sequences were conserved in all isolates. Geometric mean of reciprocal hemolytic titers for pyelonephritis isolates was 27.9; for urinary catheter isolates, 18.0; and for fecal isolates, 55.7 (not significantly different, P greater than .1). Although in vivo expression of urease and hemolysin may not be reliable indexes of virulence, MR/P hemagglutination in the absence of MR/K hemagglutination may be necessary for development of pyelonephritis.

Proteus mirabilis isolates of different origins do not show correlation with virulence attributes and can colonize the urinary tract of mice

“…No correlation between haemolytic activity and origin of isolates could be established. Our results are in accordance with those reported by Mobley & Chippendale (1990), who did not find significant differences between the haemolytic activity of P. mirabilis strains isolated from pyelonephrithis, and that of catheterassociated and faecal strains.…”

“…b-Haemolytic activity was determined by plating bacteria onto blood agar base medium supplemented with 5 % (v/v) ovine blood. Haemolytic activity was titred using the procedure described by Mobley & Chippendale (1990).…”

“…In this study, all P. mirabilis isolates showed strong production of urease. However, although urease can be associated with stone formation and serious kidney damage, it cannot be used as an index of virulence, since nearly all P. mirabilis strains produce this enzyme (Mobley & Chippendale, 1990).…”

“…Several authors have investigated P. mirabilis virulence factor distribution among strains from different sources, although data are not extensive or conclusive. Mobley & Chippendale (1990) suggest that P. mirabilis mannose-resistant, Proteus-like (MR/P) haemagglutinin can be significantly more predominant in pyelonephritogenic isolates compared to those from asymptomatic bacteriuria and faecal strains. However, the same authors suggest that expression of urease, a major uropathogenic P. mirabilis virulence factor, is present in all isolates from any source (Mobley & Chippendale, 1990).…”

“…Mobley & Chippendale (1990) suggest that P. mirabilis mannose-resistant, Proteus-like (MR/P) haemagglutinin can be significantly more predominant in pyelonephritogenic isolates compared to those from asymptomatic bacteriuria and faecal strains. However, the same authors suggest that expression of urease, a major uropathogenic P. mirabilis virulence factor, is present in all isolates from any source (Mobley & Chippendale, 1990). Gaastra et al (1996) assessed the presence and expression of genes of MR/P and uroepithelial cell adhesion (UCA) fimbriae, and production of haemolysin in P. mirabilis strains isolated from the urine and faeces of dogs with UTI.…”