title: Evaluation of four qualitative methods for detection of beta-lactamase production in Staphylococcus and Micrococcus species.
abstract: Four qualitative methods for the detection of beta-lactamase production in Staphylococcus and Micrococcus species were evaluated and compared with a quantitative macroiodometric reference method. The disc diffusion test with penicillin G and the cloverleaf method could not separate beta-lactamase-positive from beta-lactamase-negative strains. Two applications of the chromogenic cephalosporin test, using uninduced strains and strains grown on blood agar plates, gave a large number of false negative and false positive results. False negative reactions were most common among uninduced strains, while the false positive reactions were most often recorded for Staphylococcus saprophyticus. A high degree of efficiency was recorded for the nitrocefin spot test, using induced strains grown on antibiotic susceptibility agar, and for the starch-iodine plate method. The starch-iodine plate with methicillin as inducer gave the most reliable results.
authors.affiliation: Department of Clinical Microbiology, Lund Hospital, Sweden.
authors.forename: A C
authors.initials: AC
authors.lastname: Petersson
authors.forename: I
authors.initials: I
authors.lastname: Eliasson
authors.forename: C
authors.initials: C
authors.lastname: Kamme
authors.forename: H
authors.initials: H
authors.lastname: Miörner
mesh_terms: D001431:Bacteriological Techniques; D002511:Cephalosporins / Q000494:pharmacology; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D008826:Microbial Sensitivity Tests; D008837:Micrococcus / Q000187:drug effects / Q000201:enzymology*; D010400:Penicillin G / Q000494:pharmacology; D013210:Staphylococcus / Q000187:drug effects / Q000201:enzymology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000201:enzymology; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D002511:Cephalosporins; D001618:beta-Lactamases; C021720:nitrocefin; D010400:Penicillin G