Learning about tubercle bacilli is quick and easy

- neither gram negative nor gram positive
- acid fast. resembles gram negative

• very thick
• has mycolic acid

- membrane is even less fluid than some of the other membranes
- infection by inhalation or ingestion
- invades macrophages
- tubercle (nodule) is primary lesion. Forms at initial site of infection
- eventually, more macrophages attracted by cytokines will be able to fight the pathogen

• will destroy (or at least arrest) the bacilli
• will also destroy tissue and exacerbate disease

- diagnosis: lesions are characteristic. However, must culture M. bovis to confirm
- positive test doesn't necessarily indicate dz; probably indicates persistence of bacilli
- vaccines: killed vaccines not effective. BCG most dominent TB vaccine in the world. Animals not vaccinated b/c then would always test positive.