UMMS Affiliation

University of Massachusetts Medical Center

Publication Date


Document Type



Bacteria; *Bacteriological Techniques; Bacteroides fragilis; *Cephalosporins; Chromogenic Compounds; Drug Resistance, Microbial; Evaluation Studies as Topic; Haemophilus influenzae; Humans; Indicators and Reagents; Moraxella (Branhamella) catarrhalis; Neisseria gonorrhoeae; Sensitivity and Specificity; Staphylococcus aureus; beta-Lactamases




S1, a new chromogenic cephalosporin (International BioClinical, Inc., Portland, Oreg.), was used to detect beta-lactamase production among a variety of commonly encountered bacteria in a four-center collaborative study. Results of an S1 disk assay were compared with those obtained by a nitrocefin-based disk procedure (Cefinase; Becton-Dickinson Microbiology Systems, Cockeysville, Md.), with repetitive testing of five quality control organisms and with individual tests of recent clinical isolates of Neisseria gonorrhoeae (162 strains), Haemophilus influenzae (162 strains), Moraxella catarrhalis (155 strains), Staphylococcus aureus (161 strains), and Bacteroides fragilis (164 strains). The performances of the two beta-lactamase disk assays were comparable for the first three species cited above. However, the S1 assay appeared to be a more sensitive procedure than the Cefinase assay when applied to S. aureus and B. fragilis, with respect to both total numbers of positive results and length of time to a definitive positive endpoint.


J Clin Microbiol. 1995 Jun;33(6):1665-7.

Journal/Book/Conference Title

Journal of clinical microbiology

Related Resources

Link to Article in PubMed

PubMed ID


Included in

Microbiology Commons



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.