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Hemagglutinin, urease, and hemolysin production by Proteus mirabilis from clinical sources
1Department of Medicine, University of Maryland School of Medicine, Baltimore 21201.
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.
Insights
Proteus mirabilis causing pyelonephritis may require specific adherence factors. Mannose-resistant/Proteus-like (MR/P) hemagglutination, without mannose-resistant/Klebsiella-like (MR/K) hemagglutinin, appears crucial for developing this serious urinary tract infection complication.
Area of Science:
- Microbiology
- Infectious Diseases
- Urology
Background:
- Proteus mirabilis is a significant cause of urinary tract infections (UTIs).
- UTIs caused by P. mirabilis can progress to severe conditions like pyelonephritis.
- Bacterial virulence factors, including adherence factors, urease, and hemolysin, are implicated in P. mirabilis pathogenicity.
Purpose of the Study:
- To compare the expression of adherence factors, urease, and hemolysin in P. mirabilis isolates.
- To investigate the association of these virulence factors with acute pyelonephritis versus catheter-associated bacteriuria and fecal isolates.
- To determine if specific hemagglutinin profiles are necessary for the development of pyelonephritis.
Main Methods:
- Comparison of P. mirabilis isolates from patients with acute pyelonephritis (n=16), catheter-associated bacteriuria (n=35), and fecal samples (n=20).
- Assessment of hemagglutinin expression (mannose-resistant/Proteus-like [MR/P] and mannose-resistant/Klebsiella-like [MR/K]).
- Quantification of urease activity and analysis of urease gene sequences via Southern blotting.
- Determination of hemolytic titers.
Main Results:
- Pyelonephritis isolates showed a higher likelihood of expressing MR/P hemagglutinin in the absence of MR/K hemagglutinin (P < .05) compared to other groups.
- Urease production and conserved urease gene sequences were similar across all isolate groups.
- Hemolytic activity did not significantly differ between pyelonephritis, catheter-associated, and fecal isolates.
Conclusions:
- In vivo expression of urease and hemolysin may not be reliable indicators of P. mirabilis virulence in pyelonephritis.
- The presence of MR/P hemagglutination without MR/K hemagglutination may be a critical factor for P. mirabilis to cause pyelonephritis.
- Specific adherence mechanisms, particularly MR/P hemagglutination, are likely essential for the pathogenesis of pyelonephritis.