Microbiology Case Study: 80 Year Old Woman with Productive Cough

An 80 year old female presented to the emergency department complaining of a productive cough, three episodes of bright red blood stained sputum, persistent night sweats, fever, chills, and weight loss. Chest imaging revealed extensive centrilobular ground glass opacities, multiple pleural based nodules, and a cavitary lesion. The patient was exposed to Mycobacterium tuberculosis as a child when her father was treated for an active infection. Direct smears were negative; respiratory cultures were performed and an AFB culture bottle flagged positive with the following gram stain and culture morphology.

Poor-staining, beaded Gram positive bacilli in clumps and cords.
Poor-staining, beaded Gram positive bacilli in clumps and cords.

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Laboratory identification:

The organism was auramine fluorescent stain positive from the broth. The AFB culture bottle was sub-cultured to agar based medium in addition to Lowenstein-Jensen medium, which yielded buff colored colonies with a dry bread-crumb like appearance, raising concern for Mycobacterium tuberculosis. Species identification was confirmed by DNA probe.

Discussion:

Definitive diagnosis of Mycobacterium tuberculosis is based on microscopy, culture, and/or PCR. The organisms are typically acid fast, straight or slightly curved rods that occur singly or in small clumps in clinical specimens. They may grow as twisted rope-like colonies called serpentine cords in liquid medium and take up to 2-4 weeks to grow in culture. They are obligate aerobes.

TB is transmitted by inhalation of bacilli in contaminated respiratory droplets. In an immunocompetent host, primary, latent, or reactivation pulmonary infection may occur. Reactivation disease and disseminated (military) disease is possible in immunocompromised patients including those with HIV, transplant recipients, and the elderly. TB also causes meningitis, pleurisy, and spinal infections.

The virulence of the organism is likely multifactorial and is believed to be related to its ability to survive within macrophages. It is treated with multi-drug antimicrobial therapy.

 

-Lauren Pearson, D.O. is a 2nd year anatomic and clinical pathology resident at the University of Vermont Medical Center.

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-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Assistant Professor at the University of Vermont.

World TB Day

Did you know? March 24th was World TB Day. The date commemorates the day in 1882 when Dr. Robert Koch announced he’d discovered the cause of Tuberculosis.

Did you know? Every day there are 24,000 new cases of TB diagnosed. This means more than 2 billion people are infected with TB and 1.5 million people die each year (according to the Stop TB Partnership).

Did you know? The number of people diagnosed with multi-drug resistant TB (MDR-TB) has tripled since 2009 (according to the WHO TB fact sheet).

The burden of TB is highest in resource limited countries and in places where the incidence of HIV is highest. TB is the most common opportunistic infection for individuals with HIV/AIDS and is the most common cause of death in HIV/AIDS patients. In resource limited countries diagnosis and consistent treatment is a challenge. Lack of laboratory resources to use for diagnosis means TB diagnosis are often made based on empirical signs and symptoms.

Once a patient is diagnosed (either clinically or based upon a confirmed laboratory test) given the strenuous treatment, it can be difficult to keep people on a consistent treatment plan. Most treatment lasts six to nine months. In rural settings where access to drugs is limited this can be a prohibitive amount of time. Not only does the cost of the drug add up but the opportunity cost involved in missing work to travel to get the drug, the cost of the travel, and the physical strain of the travel all hamper a patient’s ability and commitment to sticking with the full course.   This can and has led to increased prevalence of MDR-TB.

Unfortunately, the ways to prevent the spread of MDR-TB (quick, accurate diagnosis; taking medication exactly as prescribed; avoiding exposure) aren’t easy in resource limited areas. Basic cell phone technology may be one tool helping to make a difference, however. Some researchers and health care providers are experimenting with sending text message reminders to other health care providers and/or patients to take their medication. Multiple studies are currently underway to determine whether this method of communication has been useful in increasing drug regimen adherence and improving the TB cure rate. If this can solve one of the challenges related to TB, it will be a big step in the right direction.

 

Levy

-Marie Levy spent over five years working at American Society for Clinical Pathology in the Global Outreach department.