A rapid technique for detection of resistance to chloramphenicol in Streptococcus pneumoniae and comparison with minimum inhibitory concentration and disk-diffusion methods.
Fifty-two strains of Streptococcus pneumoniae were examined for production of chloramphenicol acetyltransferase (CAT) by a rapid technique based upon induction of enzyme activity and chemical assay. This method was compared with one measuring the minimum inhibitory concentration (MIC) by agar dilution and a diffusion test with disks containing 10 micrograms, 30 micrograms and 50 micrograms of chloramphenicol. The MIC for 13 chloramphenicol-resistant strains was 16 mg/L and for 39 sensitive strains less than or equal to 4 mg/L. The chemical assay clearly distinguished resistant from sensitive strains; it was technically simple and provided results within 90 min. The distinction between sensitive and resistant bacteria in the disk diffusion assay was clearer with 10-micrograms than with 30-microgram and 50-micrograms disks. However, the chemical CAT assay, with enzyme induction, is recommended when a rapid result is required.
Clinical Microbiology and Public Health Laboratory, Addenbrooke's Hospital, Cambridge.
C W
CW
Walker
D F
DF
Brown
D001431:Bacteriological Techniques; D002701:Chloramphenicol / Q000378:metabolism*; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis*; D002702:Chloramphenicol Resistance; D006801:Humans; D013296:Streptococcus pneumoniae / Q000201:enzymology*
D002701:Chloramphenicol; D015500:Chloramphenicol O-Acetyltransferase