Rapid identification of penicillinase-producing Neisseria gonorrhoeae by detection of beta-lactamase in urethral exudates.

The production of fluorescent end-products with ampicillin as substrate can be used to detect beta-lactamase activity in biological fluids. A fluorescent spot test was evaluated as a rapid method of detecting beta-lactamase in the urethral exudates of men infected with Neisseria gonorrhoeae in Thailand. Among 208 men with culture-proven gonococcal urethritis, the fluorescent spot test was positive in 92 of 101 men from whom penicillinase-producing N gonorrhoeae (PPNG) were isolated and in 4 of 107 men from whom non-PPNG were isolated. The fluorescent spot test is a rapid, inexpensive, and sensitive method to detect PPNG and may be valuable in determining appropriate treatment for patients with gonococcal urethritis.