Tuberculosis is a chronic, progressive mycobacterial infection, often with an asymptomatic latent period following initial infection. Tuberculosis most commonly affects the lungs. Symptoms include productive cough, fever, weight loss, and malaise. Diagnosis is most often by sputum smear and culture and, when available, by nucleic acid amplification tests. Treatment is with multiple antimicrobial drugs given for at least 4 months.
Also known as generalized hematogenous TB, miliary TB occurs when a tuberculous lesion erodes into a blood vessel, disseminating millions of tubercle bacilli into the bloodstream and throughout the body. Uncontrolled massive dissemination can occur during primary infection or after reactivation of a latent focus. The lungs and bone marrow are most often affected, but any site may be involved.
Miliary TB is most common among
Children < 4 years old
Immunocompromised people
Older people
Symptoms of miliary TB include fever, chills, weakness, malaise, and often progressive dyspnea. Intermittent dissemination of tubercle bacilli may lead to a prolonged fever of unknown origin (FUO). Bone marrow involvement may cause anemia, thrombocytopenia, or a leukemoid reaction.
Infection of the kidneys may manifest as pyelonephritis (eg, fever, back pain, pyuria) without the usual urinary pathogens on routine culture (sterile pyuria). Infection commonly spreads to the bladder and, in men, to the prostate, seminal vesicles, or epididymis, causing an enlarging scrotal mass. Infection may spread to the perinephric space and down the psoas muscle, sometimes causing an abscess on the anterior thigh.
Salpingo-oophoritis can occur after menarche, when the fallopian tubes become vascular. Symptoms include chronic pelvic pain and sterility or ectopic pregnancy due to tubal scarring.
Meningitis often occurs in the absence of infection at other extrapulmonary sites. In the US, it is most common among the elderly and immunocompromised, but in areas where TB is common among children, TB meningitis usually occurs between birth and 5 years. At any age, meningitis is the most serious form of TB and has high morbidity and mortality. It is the one form of TB shown to be prevented in childhood by vaccination with BCG.
Symptoms are low-grade fever, unremitting headache, nausea, and drowsiness, which may progress to stupor and coma. Kernig and Brudzinski signs may be positive. Because the early signs are non-specific, it is important to consider the diagnosis early in any patient with known TB exposure, infection, or disease, including past TB, and in all persons with compatible symptoms from high TB-burden locations. Stages are
1: Clear sensorium with abnormal CSF
2: Drowsiness or stupor with focal neurologic signs
3: Coma
Stroke may result from thrombosis of a major cerebral vessel. Focal neurologic symptoms suggest a tuberculoma.
Peritoneal infection represents seeding from abdominal lymph nodes or from salpingo-oophoritis. Peritonitis is particularly common among people with alcohol use disorder who have cirrhosis.
Symptoms may be mild, with fatigue, abdominal pain, and tenderness, or severe enough to mimic acute abdomen.
Pericardial infection may develop from foci in mediastinal lymph nodes or from pleural TB. In some high-incidence parts of the world, TB pericarditis is a common cause of heart failure.
Patients may have a pericardial friction rub, pleuritic and positional chest pain, or fever. Pericardial tamponade may occur, causing dyspnea, neck vein distention, paradoxical pulse, muffled heart sounds, and possibly hypotension.
Tuberculous lymphadenitis (scrofula) typically involves the lymph nodes in the posterior cervical and supraclavicular chains. Infection in these areas is thought to be due to contiguous spread from intrathoracic lymphatics or from infection in the tonsils and adenoids. Mediastinal lymph nodes are also commonly enlarged as a part of primary pulmonary disease.
Cervical tuberculous lymphadenitis is characterized by progressive swelling of the affected nodes. In advanced cases, nodes may become inflamed and tender; the overlying skin may break down, resulting in a draining fistula.
Cutaneous tuberculosis (scrofuloderma) results from direct extension of an underlying TB focus (eg, a regional lymph node, an infected bone or joint) to the overlying skin, forming ulcers and sinus tracts.
Lupus vulgaris results from hematogenous or lymphogenous dissemination to the skin from an extracutaneous focus in a sensitized patient.
Cutaneous Tuberculosis (Lupus Vulgaris)
Tuberculosis verrucosa cutis (prosector's wart) occurs after exogenous direct inoculation of the mycobacteria into the skin of a previously sensitized patient who has moderate to high immunity against the bacilli.
Rarely, TB develops on abraded skin in patients with cavitary pulmonary TB.
Weight-bearing joints are most commonly involved, but bones of the wrist, hand, and elbow may also be affected, especially after injury.
An example is Pott disease.
Pott disease is spinal infection, which begins in a vertebral body and often spreads to adjacent vertebrae, with narrowing of the disk space between them. Untreated, the vertebrae may collapse, possibly impinging on the spinal cord. Symptoms include progressive or constant pain in involved bones and chronic or subacute arthritis (usually monoarticular). In Pott disease, spinal cord compression causes neurologic deficits, including paraplegia; paravertebral swelling may result from an abscess.
Because the entire gastrointestinal (GI) mucosa resists TB invasion, infection requires prolonged exposure and enormous inocula. It is very unusual in countries where bovine TB is rare (eg, because of milk pasteurization and routine TB testing of cattle).
Ulcers of the mouth and oropharynx may develop from eating M. bovis–contaminated dairy products; primary lesions may also occur in the small bowel. Intestinal invasion generally causes hyperplasia and an inflammatory bowel syndrome with pain, diarrhea, obstruction, and hematochezia. It may also mimic appendicitis. Ulceration and fistulas are possible.
Liver infection is common in patients with advanced pulmonary TB and widely disseminated or miliary TB. However, the liver generally heals without sequelae when the principal infection is treated. TB in the liver occasionally spreads to the gallbladder, leading to obstructive jaundice.