Tuberculosis and Mycobacteria
On March 24, 1882, German physician Robert Koch announced the discovery of Mycobacterium tuberculosis, the organism that causes tuberculosis (TB), a disease that had plagued humanity for centuries, caused more deaths than any other disease in industrialized countries during the 19th and early 20th centuries, and remains a leading cause of death in the world. March 24 is now commemorated as World TB Day in honor of Koch’s discovery, which EID commemorates by making mycobacteria or TB (caused by a type of mycobacteria) the theme for its March issues.
TB bacteria are spread through the air from one person to another. Typically, the bacteria settle in the lungs and begin to grow. From there, they can move through the blood to other parts of the body, including the kidney, spine, and brain. Some people who are infected with TB bacteria do not become sick because their immune systems are able to wall off or surround the bacteria and prevent them from growing. This is called latent TB infection, and many people with latent TB infection never develop TB disease. In others, especially people who have weakened immune systems, the bacteria become active, multiply, and cause TB disease. TB disease typically begins with a cough that produces mucus. If left untreated, the disease advances, and victims begin to cough up blood as their lungs are gradually destroyed.
Literature from the 19th and early 20th centuries is rife with terrifying descriptions of healthy individuals succumbing to what was all too often a slow, painful, and suffocating death from TB. The plague of consumption (as TB was often called) doomed many of the characters in the novels of Dostoevsky (Katerina Ivanovna Marmeladov in Crime and Punishment) and the operas of Puccini (Mimi in La Bohème). The great German novelist Thomas Mann’s 900-plus-page The Magic Mountain is set almost entirely in and around a TB sanatorium in the Swiss Alps, where the main characters hope for a reprieve from an early and miserable death.
To this day, infections from mycobacteria such as Mycobacterium tuberculosis are not easy to treat. Because of their thick cell walls, these bacteria are notoriously hard to kill and can survive long exposures to harsh chemicals and detergents. They are also naturally resistant to a number of antibiotics. Emerging antimicrobial resistance is a serious concern among physicians and infectious disease experts worldwide. Humankind is now facing a global epidemic of drug-resistant TB. About 1 in 5 Mycobacterium tuberculosis isolates worldwide are resistant to at least 1 anti-TB drug, and nearly 1 quarter of the deaths from TB globally are associated with drug resistance. TB that is resistant to drugs is harder and more expensive to treat.
Mycobacteria, which include Mycobacterium tuberculosis, often grow in mold-like fashion—hence the prefix myco, derived from the Greek word for fungus (myces). These organisms are widespread and typically live in water, soil, and food. There are more than 190 species in the genus Mycobacterium, some of which are known to cause serious diseases (besides TB) in mammals, such as Hansen’s disease, better known as leprosy.
A report in this month’s issue of EID describes another particularly worrisome mycobacterium called Mycobacterium chimera, which can infect patients during open-heart surgery. During these surgeries, the patient’s blood is sometimes rerouted through a heater–cooler device to regulate blood temperature. The water used in those devices (including water treated with chlorine) can become contaminated with Mycobacterium chimera organisms, which in turn contaminate the device itself and the blood flowing through it.
EID Articles about Mycobacteria
Learn more about mycobacteria from these articles from the March issue of Emerging Infectious Diseases. For a quick overview, read the abstracts. Use the Advanced Article Search to find more articles.
• Global Health Estimate of Invasive Mycobacterium chimaera Infections Associated with Heater–Cooler Devices in Cardiac Surgery (the article mentioned earlier) describes the growing threat of a mycobacterial species that lurks in water systems and can infect patients during open heart surgery.
• Drug Resistance of Mycobacterium tuberculosis Complex in a Rural Setting, Angola describes a concerning increase in these infections in rural Angola, which has implications for the whole region.
• Increasing Prevalence of Nontuberculous Mycobacteria in Respiratory Specimens from US-Affiliated Pacific Island Jurisdictions warns us that nontuberculous mycobacteria respiratory infections represent a growing public health problem in many countries.
• Acquired Resistance to Antituberculosis Drugs in England, Wales, and Northern Ireland, 2000–2015 describes the growing challenge posed by drug-resistant M. tuberculosis in another corner of the world.
• Mycobacterium avium subsp. hominissuis Infection in a Domestic Rabbit describes a rare case of mycobacterial infection in a rabbit in Germany and its potential for spread to humans.
Sources and Additional Information
Centers for Disease Control and Prevention. World TB Day 2018.
Centers for Disease Control and Prevention. Tuberculosis.
Emerging Infectious Diseases. Etymologia: Mycobacterium.
Emerging Infectious Diseases. Keeping It in the Family: the Childhood Burden of Tuberculosis.
Hain Lifescience. Mycobacteria.
Original Issue Publication Date: 04/05/2018
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