MOHAMMED J, MARSTON CK, POPOVIC T, WEYANT RS, TENOVER FC; Interscience Conference on Antimicrobial Agents and Chemotherapy (41st : 2001 : Chicago, Ill.).
Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 2001 Dec 16-19; 41: abstract no. UL-9.
CDC, Atlanta, GA.
BACKGROUND: Clinical cases of cutaneous and inhalational anthrax resulting from the intentional release of Bacillus anthracis have been identified in several cities in the U.S. However, there is only limited information available on the antimicrobial susceptibility patterns of B. anthracis. METHODS: We determined the antimicrobial susceptibility patterns of 50 isolates of B. anthracis collected from 1937 to 1997 (20 animal and 30 human), and 12 clinical isolates from 2001, to 9 antimicrobial agents using the NCCLS reference broth microdilution (BMD) method. The results of the first 50 isolates were compared to the results generated with Etest. Inactivation of beta-lactams was assessed using a Micrococcus luteus indicator strain. RESULTS: All 12 B. anthracis isolates were susceptible to penicillin (MIC <0.06-0.12 microg/ml) and beta-lactamase (-). However, 3 of 3 isolates indicated inactivation of penicillin and cephalosporins in the Micrococcus assay. One historical isolate, which was beta-lactamase (+), was resistant to penicillin (MIC=64). 98% of 61 isolates had reduced susceptibility to ceftriaxone (MIC>8). All 61 isolates were susceptible to chloramphenicol (<4), ciprofloxacin (<0.06), clindamycin (<0.5), rifampin (<0.5), tetracycline (<0.06), and vancomycin (<2) using NCCLS staphylococcal breakpoints. 97% of isolates were intermediate to erythromycin (MIC= 1). The 12 clinical isolates were are also susceptible to amikacin, gentamicin, imipenem, and meropenem. Etest penicillin MIC results were 1-9 doubling dilutions lower than the BMD results, raising a concern that penicillin-resistant isolates of B. anthracis may be reported as susceptible by Etest. There was a better correlation between Etest and BMD results for the other 8 drugs tested. CONCLUSION: The susceptibility patterns of the 12 clinical isolates of B. anthracis are similar to those of historical isolates; all were penicillin susceptible and beta-lactamase (-), although there was indication of penicillin inactivation. BMD and Etest results correlate for most of the agents tested, except for penicillin. Because of difficulties reading Etest results in a BSL-3 safety cabinet, Etest should be used with caution.
Publication Types:
Keywords:
- Amikacin
- Bacillus anthracis
- Bacteria
- Ceftriaxone
- Chloramphenicol
- Clindamycin
- Gentamicins
- Humans
- Imipenem
- Microbial Sensitivity Tests
- Penicillins
- Research Design
- United States
- beta-Lactamases
- beta-Lactams
Other ID:
UI: 102269579
From Meeting Abstracts