According to a study done in Italy:
All five cannabinoids (THC, CBD, CBG, CBC, and CBN) were potent against bacteria. Notably, they performed well against bacteria that were known to be multidrug resistant, like the strains of MRSA that plagued U.K. hospitals. CBD and CBG have the most potential for consumer use because they are nonpsychotropic.
In plain English-- the major components of marijuana, cannabinoids, kill bacteria. It's not a huge leap to suggest that smoking pot, while harmful to the lungs, can also potentially kill bacteria in your system and keep you healthy. For all you scientists out there, the full report is here.
