Strain typing of Pseudomonas aeruginosa – most widely used historical method: Among classical laboratory methods to type clinical isolates of Pseudomonas aeruginosa for epidemiology, which became the most popular and widely applied?

Introduction / Context:
Before high-resolution molecular methods (PFGE, MLST, WGS) were routine, laboratories used phenotypic and simple genotypic approaches to type Pseudomonas aeruginosa during hospital outbreak investigations. Recognizing the most popular historical method provides context for legacy literature.

Given Data / Assumptions:

• Typing methods included antibiograms, serotyping, phage typing, and pyocin typing.
• Reliability and discrimination vary across methods.
• Question asks which became the most popular overall.

Concept / Approach:
Pyocin typing—based on patterns of bacteriocin production and susceptibility—provided higher discriminatory power than antibiograms and was more practical and reproducible than many phage-typing schemes for P. aeruginosa. As such, it gained popularity for hospital epidemiology prior to molecular dominance.

Step-by-Step Solution:
Review traditional methods and their relative discriminatory power. Identify pyocin typing as the method most widely adopted for P. aeruginosa. Select the option naming pyocin typing. Acknowledge that modern practice favors molecular approaches.

Verification / Alternative check:
Classic outbreak reports frequently cite pyocin typing patterns to track nosocomial spread.

Why Other Options Are Wrong:
Antibiograms are insufficiently discriminatory; serotyping lacks resolution; phage typing was less standardized; plasmid profiling is variable and not universally applicable.

Common Pitfalls:
Assuming antibiogram equivalence to true typing; resistance patterns can converge in unrelated strains under similar selective pressures.

Final Answer:
Pyocin typing (bacteriocin production/susceptibility).