Selective Isolation and Differentiation of Enteric Gram-Negatives: Isolates and differentiates lactose fermenters vs. nonfermenters using lactose and neutral red; bile salts #3 and crystal violet inhibit Gram-positives. Typical targets include Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and nonfermenters like Pseudomonas aeruginosa.

Fluoroquinolone-Resistance Screening: Enrichment and detection of levofloxacin-resistant Gram-negative bacilli at 16 µg/mL from stool, urine, and rectal surveillance swabs.

AMR Surveillance in Public Health and Clinical Labs: Monitoring prevalence and trends of levofloxacin-resistant enteric bacteria in patient and community samples.

Food, Water, and Environmental Testing: Enumeration and recovery of fluoroquinolone-resistant coliforms from environmental, agricultural, and food-processing samples.

Selection/Maintenance of Resistant Isolates: Culturing clinical or engineered strains with quinolone resistance (e.g., qnr genes, gyrA/parC mutations) under defined selective pressure.

Phenotypic Confirmation of Genotypic Findings: Verifying resistance gene or mutation calls by growth/no-growth at 16 µg/mL levofloxacin.

Colony Isolation for Downstream ID/AST: Obtaining well-isolated colonies for MALDI-TOF identification and follow-up susceptibility testing.

Environmental Monitoring in cGMP Facilities: Recovery of levofloxacin-resistant Gram-negative contaminants from surfaces, air, and water systems.