How is TB test different from actual microbe?

Moreover, in an actual infection, the microbes are often present inside the macrophages and are not necessarily localized in the skin. Large granulomas develop when the stimulus persists, especially if undegradable particulate materials are present and several macrophages, all attempting to ingest the same material, have fused their cell membranes to one another Although granuloma formation may be an effective method the immune system employs to sequester indigestible materials (whether of microbial origin or not ) from the rest of the body, the harm inflicted by this immune mechanism may be much more serious than the damage caused by the infectious organisms diseases as pulmonary tuberculosis and schistosomiasis and in certain fungal infections that become established within the body tissues rather than at their surface