BCG is attenuated mycobacterium bovis used worldwide to enhance resistance to mycobacterium tuberculosis in children. After vaccination of BCG, the results of tuberculin test can turn positive. In addition to improving immunity as a vaccination, it is sometimes used clinically as an immunological treatment for patients with mycobacterial infections and cancer.


Causes

Skin complications caused by vaccination of BCG are not uncommon, and the incidence of local complications can be 0.1% - 0.4%. The vaccine not well shaken before vaccination, inappropriate injection sites, too deep injections, overdoses, and individual differences can cause skin complications after vaccination.


Signs and Symptoms

Local redness and swelling occurs 2 - 3 days after normal BCG vaccination, small vesicles occur locally, subsiding soon. Specific reactions occur 1 week after vaccination. Local redness, swelling, and induration occur, with softened center, forming superficial ulcers after rupture, leaving small scars after decrustation. Abnormal reactions or complications include purplish red plaques, nodules, abscesses, and chronic ulcers at the vaccination sites. Some skin lesions are similar to scrofuloderma, lupus vulgaris, and tuberculosis verrucosa cutis, persisting for a long time. Ulcers with irregular edges and thin secretions on the surface may be present. The duration is more than 3 months.

The reactions in the non-vaccination sites are urticaria and erythema multiforme. Uncommon reactions include systemic maculopapular rash, purpura with joint pain, abdominal pain or myalgia, and lichen scrofulosorum.


Histopathology

Tuberculous granuloma and caseous necrosis can be seen.


Treatment

Block therapy for local skin lesions with streptomycin plus lidocaine once a day for the 3 days followed by once every 3 days for 21 days can be applied. Chronic ulcers can be treated with isoniazid powder or 5% isoniazid ointment once a day or once every other day. Abscesses can be punctured and pus can be drained, but incision is unsuitable in order to avoid unhealing.

3 - 6 months of systemic anti-tuberculosis treatment should be performed.

First-line anti-tuberculosis drugs include isoniazid (INH), rifampicin (RIF), pyrazinamide (PZA), and ethambutol (EMB). These drugs should be treated in combination.

Second-line anti-tuberculosis drugs are often used in drug-resistant tuberculosis patients or patients unable to tolerate first-line drugs, mainly including aminoglycosides and fluoroquinolones, such as streptomycin, kanamycin, amikacin, capreomycin, levofloxacin, and moxifloxacin. Aminoglycosides are only for parenteral use.

Other second-line drugs include ethionamide, cycloserine, and para-aminosalicylic acid, with anti-tuberculosis effect weaker than first-line drugs, with strong toxicity, but effective against drug-resistant tuberculosis.

Bedaquiline, delamanid, and sutezolid are new anti-tuberculosis drugs and are usually reserved for extensively drug-resistant tuberculosis, or patients unable to tolerate other second-line drugs.