Question

The patient was a 28-year-old female who came to the United States from the Philippines 5 years ago. Two years ago, she was diagnosed with systemic lupus erythemathosus. On admission, she stated that she had a persistent fever of 38-39°C for the past 4 weeks. Approximately 4 weeks ago the entire family became ill. The patient and her husband had symptoms consistent with an upper respiratory infection, and the children had tonsillitis but improved. The patient and her husband were prescribed azithromycin, but only her husband improved. The patient had anorexia with 15 lb of unintentional weight loss in the past few months, as well as nausea and lethargy. Her physical examination was relatively benign with the exception of an abnormal chest CT scan showing small granulomas throughout her lungs. The patient was sent for a bronchoscopy, and lavage fluid was sent to the lab for bacterial, fungal and mycobacterial cultures and stains. The bronchoalveolar lavage fluid rendered acid-fast organisms.

1. What organism was most likely causing the infection?

2. Describe the natural history of infection with these organisms. Explain the role of the host immune system (cells, cytokines) in the development of the disease.

3. The organism isolated from this patient showed resistance to Isoniazid, rifampin, pyrazinamide, ethionamide, capreomycin. How would you classify this organism? What is the global prevalence of this disease? What is the significance of her being from the Philippines?

4. What is a PPD skin test (also called Mantoux or tuberculin test)? What is its value for the patient? What additional tests are available for detecting latent infection with this organism?

Answer 1

Systemic lupus erythematosis is a chronic multisystem autoimmune disease of unknown etiology.

It can affect any organ system.

The immune dysregulation due to SLE can lead to an infection called tuberculosis.

So that TB is a common infection among SLE patients.

The main reasons for high incidence of TB infecton are immunosuppressive therapy, or immune disturbances of lupus itself.

Tuberculosis is caused by a type of bacterium called mycobacterium tuberculosis.

The route of entry of the organism into body is through the respiratory tract by the inhalation of respiratory droplet nuclei.  

The encounter between host and the organism leads to a complex and multifaceted immune response possibly result in latent infectioninfection, tubercular disease or to the complete clearance of the pathogen.

Granuloma formation is initiated by mtb infected macrophages and continues with the development of multinucleated giant cells and liquid filled foamy macrophages surrounded by a ring of lymphocytes encapsulated in a fibrotic cuff .

Multi Drug Resistant TB or MDR TB is TB that doesn't respond to at least isoniazid, and rifampicin. These are the most powerful anti TB drugs.