[Guinea pigs infected by bacterial dust aerosol of Bacillus tuberculosis]

There still is controversy over whether Bacillus tuberculosis could be spread by dust. For the purpose to illustrate the possible contagious route, guinea pigs were exposed to bacterial dust aerosol which was generated by mixing Bacillus tuberculosis H37Rv with dried dust. The percentage of the size of particles, diameter < 4 microns, was 5.1%. The density of bacteria in the dust aerosol was 386.7 cfu/L and the mass medium diameter (MMD) was 1.9 microns. On the 70 days after exposure, in the 3 minutes exposed group, positive reaction to OT test (1:20) was 2/7, culture of Bacillus tuberculosis was positive from lungs and spleen was 1/7, in the 18 minutes exposed group, 5/8 were positive for OT test, the positive culture found from lungs was 2/8 and from spleen 1/8. These results showed that Bacillus tuberculosis could be spread by bacterial aerosol.