Variable phenotypes of Providencia stuartii due to plasmid-encoded traits

Area of Science:

• Microbiology
• Infectious Diseases
• Molecular Biology

Background:

• Providencia stuartii is a significant opportunistic pathogen, frequently isolated from patients with long-term urinary catheters.
• Catheter-associated urinary tract infections (CAUTIs) pose a substantial clinical challenge, often involving multidrug-resistant bacteria.
• Understanding the virulence factors and genetic transfer mechanisms of P. stuartii is crucial for effective treatment strategies.

Purpose of the Study:

• To characterize the prevalence of key metabolic traits (urease, sucrose fermentation, lactose utilization) in Providencia stuartii isolates from catheterized patients.
• To investigate the genetic basis of these traits, specifically identifying the plasmids responsible for their transfer.

Main Methods:

• Collection and analysis of weekly urine specimens from 51 long-term catheterized patients.
• Isolation and identification of 699 bacterial strains, primarily Providencia stuartii.
• Phenotypic characterization of isolates for urease, sucrose, and lactose utilization.
• Plasmid-mediated conjugation experiments to transfer metabolic traits to a recipient strain (Escherichia coli).

Main Results:

• A total of 699 Providencia stuartii isolates were obtained.
• Urease-positive strains constituted 23.7% (166/699) of the isolates.
• Sucrose-positive strains represented 24.5% (171/699), while lactose-utilizing strains were rare (0.7%, 5/699).
• Conjugation experiments successfully transferred urease and sucrose-positive traits via an 82-kilobase plasmid.
• Lactose fermentation was transferred via a distinct 150-kilobase plasmid.

Conclusions:

• Providencia stuartii isolates from catheterized patients frequently exhibit urease and sucrose-positive phenotypes.
• These metabolic traits are plasmid-encoded and transferable, suggesting a mechanism for their dissemination.
• The findings highlight the role of specific plasmids in the adaptability and potential virulence of P. stuartii in the urinary tract environment.