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Influence of pili on the virulence of Proteus mirabilis in experimental hematogenous pyelonephritis

F J Silverblatt, I Ofek

    The Journal of Infectious Diseases
    |November 1, 1978
    PubMed

    Insights

    Heavy pili on Proteus mirabilis hinder kidney infection, contrary to expectations. Lightly piliated bacteria caused abscesses, while heavily piliated strains were eliminated, suggesting pili may impair renal parenchyma survival.

    Area of Science:

    • Microbiology
    • Urology
    • Infectious Diseases

    Background:

    • Proteus mirabilis is a common cause of urinary tract infections.
    • Pili, hair-like appendages on bacteria, are often associated with virulence and host cell attachment.
    • The role of pili in Proteus mirabilis renal infection, particularly within the kidney parenchyma, requires further investigation.

    Purpose of the Study:

    • To compare the infectivity of heavily and lightly piliated Proteus mirabilis in a hematogenous pyelonephritis model.
    • To investigate the impact of piliation levels on bacterial survival and abscess formation within the renal parenchyma.

    Main Methods:

    • A rat model of hematogenous pyelonephritis was utilized.
    • Rats were injected with either lightly or heavily piliated Proteus mirabilis.
    • Bacterial clearance from vasculature, delivery to the kidney, and abscess formation were monitored.

    Main Results:

    • Cortical abscesses were observed in 13 of 24 rats infected with lightly piliated P. mirabilis, but in none of the 24 rats infected with heavily piliated strains (P < 0.001).
    • Both bacterial strains were cleared equally rapidly from the vasculature and delivered to the kidney in similar numbers.
    • While lightly piliated bacteria increased significantly in kidney titers within 24 hours, heavily piliated P. mirabilis were largely eliminated.

    Conclusions:

    • Pili, previously thought to enhance virulence in Proteus mirabilis kidney infections, may actually impede bacterial survival within the renal parenchyma.
    • Heavy piliation appears to be detrimental to bacterial persistence and abscess formation in this hematogenous pyelonephritis model.
    • These findings challenge the conventional understanding of pili function in Proteus mirabilis pathogenesis within the kidney.

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