Yes. Microbes once in the blood stream can cross/bypass the barrier by a few ways such as by crossing endothelial cells, crossing loosened or disrupted tight ju

Yes. Microbes once in the blood stream can cross/bypass the barrier by a few ways such as by crossing endothelial cells, crossing loosened or disrupted tight junctions or by entering a host cell that then traverses the barrier. Normally, intact cell-mediated immunity prevents harmless airway colonization of these types of organisms from entering the blood stream or causing clinical infection hence why they're called opportunistic infections. Rare in immunocompetent patients.