[Rapid ATB staph: 4-hour antibiotic sensitivity test of staphylococci. Description and performance]

Abstract

Rapid ATB Staph is a method for four-hour antimicrobial susceptibility testing of staphylococci. The equipment and theoretical basis are identical to those already described for rapid testing of enterobacteriaceae. A standardized procedure is required to perform the test. The inoculum should be prepared from a culture no older than 24 hours and accurately standardized at 10(8). Temperature of incubation should be 35 degrees C to 37 degrees C; otherwise growth is delayed by approximately one hour. Time of incubation should not exceed 5 hours. Using these standardized conditions, rapid ATB Staph was compared with the reference agar dilution method for 22 antibiotics. Overall agreement was 96.3%. The rapid system is more sensitive than the reference method fort the detection of netilmicin and amikacin resistance; it is reliable for detecting penicillin resistance, oxacillin resistance and inducible resistance to erythromycin (agreement 96.7%, 94.8% and 98.4% respectively). A Rapid ATB Staph strip containing 15 antibiotics has been designed for routine susceptibility testing.