Fred C. Tenover1*. Epidemiology and Laboratory Branch, ...... In P. R. Murray, E. J. Baron, M. A. Pfaller, F. C. Tenover, and. R. H. Yolken (ed.), Manual of clinical ...
JOURNAL OF CLINICAL MICROBIOLOGY, June 2002, p. 1902–1907 0095-1137/02/$04.00⫹0 DOI: 10.1128/JCM.40.6.1902–1907.2002
Vol. 40, No. 6
Antimicrobial Susceptibility Testing of Bacillus anthracis: Comparison of Results Obtained by Using the National Committee for Clinical Laboratory Standards Broth Microdilution Reference and Etest Agar Gradient Diffusion Methods M. Jasmine Mohammed,1 Chung K. Marston,2 Tanja Popovic,2 Robbin S. Weyant,2 and Fred C. Tenover1* Epidemiology and Laboratory Branch, Division of Healthcare Quality Promotion,1 and Meningitis and Special Pathogens Branch, Division of Bacterial and Mycotic Diseases,2 Centers for Disease Control and Prevention, Atlanta, Georgia 30333 Received 30 November 2001/Returned for modification 7 January 2002/Accepted 1 March 2002
We determined the patterns of antimicrobial susceptibility of 65 isolates of Bacillus anthracis (50 historical and 15 recent U.S. clinical isolates) to nine antimicrobial agents using the National Committee for Clinical Laboratory Standards (NCCLS) broth microdilution reference method. The results for the 50 historical B. anthracis isolates obtained by the broth microdilution method were compared to those generated by the Etest agar gradient diffusion method. One isolate of B. anthracis was -lactamase positive and resistant to penicillin (MIC, 128 g/ml); a second isolate, which was -lactamase negative, was borderline penicillin resistant, with the penicillin MICs for the isolate varying from 0.12 to 0.25 g/ml; and the remainder of the isolates were -lactamase negative and penicillin susceptible (MICs, 16 g/ml). All B. anthracis isolates were susceptible to chloramphenicol (MICs,
