Comparison of three rapid tests for the detection of β-lactamase production among bacterial isolates

The current study compares the performance and evaluated the practicality of three rapid detection methods for β-lactamase production among 48 veterinary bacterial isolates (16 S. aureus, 18 E. coli, and 14 S. typhimurium) in Korea. Antimicrobial susceptibility was determined by broth microdilution method and β-lactamase production was detected by iodometric, acidimetric, and chromogenic methods. Seventy five percent of S. aureus, 44% of E. coli, and 35% of S. typhimurium were resistant to penicillin, ampicillin, and amoxicillin, respectively. Overall, the iodometric test yielded the highest positive results (91.67%), followed by chromogenic test (66.67%) and acidimetric test (47.92%). The sensitivities and specificities of the three different tests varied for S. aureus, E. coli, and S. typhimurium isolates. Our results showed that these test methods may applicable to monitor β-lactamase production among various microorganisms and to predict β-lactam antibiotic resistance.