Tuberculosis

Key Features

Essentials of Diagnosis

• All types: positive tuberculin test in patient or members of household, suggestive chest radiograph, history of contact, and demonstration of organism by stain and culture

• Pulmonary: fatigue, irritability, and undernutrition, with or without fever and cough

• Glandular: chronic cervical adenitis

• Miliary: classic snowstorm appearance of chest radiograph

• Meningitis: fever and manifestations of meningeal irritation and increased intracranial pressure, with characteristic CSF

General Considerations

• Caused by Mycobacterium tuberculosis

• Children younger than age 3 years are most susceptible

• Lymphohematogenous dissemination through the lungs to extrapulmonary sites, including the brain and meninges, eyes, bones and joints, lymph nodes, kidneys, intestines, larynx, and skin, is more likely to occur in infants

• Increased susceptibility occurs again in adolescence, particularly in girls within 2 years of menarche

• Exposure to an infected adult is the most common risk factor in children

Demographics

• Tuberculosis cases have declined from a high of 26,673 new cases in 1992 to 9,582 new cases reported in 2013

• Only 485 of these new cases were in children less than 14 years old

• High-risk groups include ethnic minorities, foreign-born persons, prisoners, residents of nursing homes, indigents, migrant workers, and healthcare providers

• HIV infection is an important risk factor for both development and spread of disease

Clinical Findings

Symptoms and Signs

• Choroidal tubercles are sometimes seen on funduscopic examination

• Other lesions may be present and produce osteomyelitis, arthritis, meningitis, tuberculomas of the brain, enteritis, or infection of the kidneys and liver

• In meningitis, fever, vomiting, headache, lethargy, and irritability, with signs of meningeal irritation and increased intracranial pressure, cranial nerve palsies, convulsions, and coma

• Enlarged cervical lymph nodes usually present in a subacute manner; involved nodes may become fixed to the overlying skin, suppurate, and drain

Differential Diagnosis

• Fungal, parasitic, mycoplasmal, and bacterial pneumonias

• Lung abscess

• Foreign body aspiration

• Lipoid pneumonia

• Sarcoidosis

• Mediastinal cancer

• Cat-scratch fever and infection with atypical mycobacteria

• Viral meningoencephalitis, head trauma (child abuse), lead poisoning, brain abscess, acute bacterial meningitis, brain tumor, and disseminated fungal infections must be excluded in tuberculous meningitis

Diagnosis

Laboratory Findings

• Tuberculin skin test (TST; 0.1 mL of intermediate-strength purified protein derivative inoculated intradermally) is positive at 48–72 hours if there is significant induration

• Temporary suppression of tuberculin reactivity may be seen with viral infections (eg, measles, influenza, varicella, and mumps), after live virus immunization, and during corticosteroid or other immunosuppressive drug therapy

• Interferon gamma release assays (IGRAs) are approved to replace TST tests in children older than 4 years

• ESR and CRP is usually elevated in symptomatic children

• CSF in tuberculous meningitis shows slight to moderate pleocytosis (50–300 WBCs/μL, predominantly lymphocytes), decreased glucose, and increased protein

• Direct detection ...