Modified MacConkey medium which allows simple and reliable identification of Providencia stuartii

Area of Science:

• Microbiology
• Clinical Diagnostics
• Bacteriology

Background:

• Providencia stuartii is an emerging nosocomial pathogen.
• Accurate and rapid identification of P. stuartii is crucial for effective patient management.
• Current diagnostic methods may exhibit limitations in specificity and sensitivity.

Purpose of the Study:

• To develop and validate a modified MacConkey medium (MCP medium) for the simple and accurate identification of Providencia stuartii.
• To compare the efficacy of MCP medium with standard MacConkey medium and commercial identification kits.

Main Methods:

• A total of 813 bacterial strains from Enterobacteriaceae and Pseudomonadaceae families were tested on MCP medium.
• Phosphatase activity was assessed for P. stuartii and other related species.
• Comparative analysis with standard MacConkey medium and the API 20E system was performed.
• Clinical validation was conducted using urine samples from elderly patients over a 6-month period.

Main Results:

• MCP medium demonstrated high specificity for P. stuartii, with all strains showing positive phosphatase activity.
• 97.5% of Morganella morganii strains were also phosphatase positive, distinguishable by ornithine or citrate tests.
• MCP medium coupled with the API 20E system correctly identified all P. stuartii isolates in clinical samples.
• Standard MacConkey medium resulted in significant misidentification rates for P. stuartii when used with the API 20E system.

Conclusions:

• MCP medium offers a simple, reliable, and accurate method for identifying Providencia stuartii.
• This modified medium enhances diagnostic accuracy in clinical laboratories, reducing misidentification rates.
• MCP medium represents a valuable tool for the early detection and management of P. stuartii infections.