Bacillus anthracis antibiotic resistance

Many diseases, including anthrax, are most effectively treated before actual manifestation of the symptoms is observed. Presently a presumptive identification of Bacillus anthracis can be made in about 3 hours however, if a full laboratory response network (LRN) confirmation procedure is utilized, the theoretical time increases substantially to approximately 48 hours. During the recent anthrax cases 72 to 96 hours were common to complete the entire LRN protocol. In the meantime antibiotics were administered as a precaution based on the presumptive results to individuals thought to be exposed to B. anthracis spores or with anthrax symptoms. The mass administering of antibiotics from a cost standpoint, as well as from medical prudence to prevent the rise of antibiotic-resistant strains, is not the optimal answer to the anthrax infection problem. Therefore it is important that early tests be rapid and reliable with a minimum number of false positive and false negative results. 

Yes, there are different strains of Bacillus anthracis. Some strains of B. anthracis may be naturally resistant to certain antibiotics and not others. In addition, there may be biologically mutant strains that are engineered to be resistant to various antibiotics. A laboratory analysis can help to define which. strain of B. anthracis is present and which antibiotic would be the most effective in treating the resulting anthrax. 

At the beginning of the recent anthrax outbreak, investigators did not know which drugs would kill the. strains of Bacillus anthracis responsible for the outbreak. They used ciprofloxacin because veiy few bacteria are resistant to it. Recent laboratoiy tests using all of the B. anthracis strains from tlie lecent outbreak have indicated that all the strains are susceptible to ciprofloxacin, doxycydine, and other antibiotics. 

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