Direct detection of Bacillus anthracis DNA in animals by polymerase chain reaction.

Bacillus anthracis is a soil pathogen capable of causing anthrax. To establish a method for specifically detecting B. anthracis for practical applications, such as for the inspection of slaughterhouses, the cap region, which is essential for encapsulation in B. anthracis, was used in a DNA hybridization study by polymerase chain reaction (PCR). Oligonucleotide primers were designed to amplify a 288-bp DNA fragment within the capA gene by PCR. The amplified DNA sequence specifically hybridized to the DNA of B. anthracis but not to that of other bacterial strains tested. Since this PCR-based method efficiently and specifically detected the capA sequence of bacteria in blood and spleen samples of mice within 8 h after the administration of live B. anthracis, this PCR system could be used for practical applications. By using lysis methods in preparing the samples for PCR, it was possible to amplify the 288-bp DNA segment from samples containing very few bacteria, as few as only 1 sporeforming unit, indicating that the PCR detection method developed in this study will permit the monitoring of B. anthracis contamination in the environment.