Infectious Diseases A to Z – Extensively Drug-Resistant (XDR) Tuberculosis

With this new column, Elite Healthcare will compile an index of various infectious diseases, with occasional highlights of emerging conditions. 

Extensively Drug-Resistant (XDR) Tuberculosis

General definition and information: 

A rare type of tuberculosis that is multidrug-resistant to the most powerful types of tuberculosis treatments and further reduces the efficacy of alternative options. Particularly problematic to those patients who are living with HIV and other chronic immune-compromising conditions, XDR only accounted for 63 cases of tuberculosis in the United States between 1993 and 2001, according to the National Tuberculosis Surveillance System, but is still quite contagious and can spread in airborne fashion like the general type of tuberculosis. Symptoms of tuberculosis disease depend on the area of the body affected, but typically include a feeling of sickness and/or weakness, weight loss, fever, and night sweats. If tuberculosis is present in the lungs, symptoms may also include coughing, chest pain, and coughing up blood. 

According to the Centers for Disease Control and Prevention (CDC), an apparent increase in XDR tuberculosis worldwide over the last several years may be more linked to better laboratory testing and detection.1 

Causes & Modes of Transmission: 

Tuberculosis is caused by the bacterium mycobacterium tuberculosis, which can affect any part of the body but usually attacks the lungs. The kidneys, spine, and brain are also organs that may likely be impacted by the disease. The bacteria are spread human to human through the air after a person who has been infected with the disease of the lungs or throat coughs, speaks, or even sings, according to the CDC. The disease has the potential to be spread to anyone nearby if they breathe in the bacteria.

The bacteria are not able to be passed along to other people through other ways of disease transmission such as hand shaking, food sharing, dirty surfaces, sharing a toothbrush, or kissing. Once someone is infected with the bacteria, they bacteria can begin to grow and spread through the blood to other parts of the body. (According to the CDC, tuberculosis that occurs in body parts outside of the lungs is typically expected to be infectious.2) Not all infected people will become sick, however the disease can prove to be fatal if not diagnosed and treated appropriately.

XDR tuberculosis is spread in the same manner and is more common among people who do not take their tuberculosis medicine as prescribed, develop the disease multiple times, have spent time in regions of the world where drug-resistant types of the disease are common, and/or have spent time with someone known to have the drug-resistant type of the disease.

Treatment Strategies: 

Tuberculosis in general is treated over a course of antibiotics over 6-9 months. Although the to the XDR type of tuberculosis can be difficult to treat and is problematic against the antibiotics isoniazid and rifampin, the two strongest tuberculosis drugs, as well as any antibiotic in the fluoroquinolone class and at least one of three injectable second-line drugs (i.e., amikacin, kanamycin, or capreomycin), the CDC reports that some cases of the XDR disease can be treated and cured. Some tuberculosis control programs have shown that a cure is possible for an estimated 30%-50% of affected people.1 According to the CDC, successful outcomes depend primarily on the extent of drug resistance, disease severity, strength of the patient’s immune system, and adherence to treatment. While diagnosis of tuberculosis can be made in 1-2 days following infection, distinguishing between drug-susceptible types of the disease and drug-resistant types of the disease must wait until the bacteria have grown and can be tested in a specialized laboratory, which may take 6-16 weeks, according to the CDC.

The CDC suggests that XDR disease be managed by or in close consultation with an expert in the disease because inappropriate management can be life-threatening. However, The U.S. Food and Drug Administration (FDA) has advised restricting fluoroquinolone antibiotic use for certain uncomplicated infections due to adverse effects from these medications.3 Specifically, FDA officials indicate that the risks of adverse effects of fluoroquinolone drugs generally outweigh the benefits for patients with sinusitis, bronchitis, and uncomplicated urinary tract infections who have other treatment options.

Fluoroquinolone antibacterial drugs will be necessary for some patients who have drug-resistant disease or drug-resistant latent infection, or who cannot tolerate first-line drugs, according to the CDC. Healthcare providers who are unsure of or who have questions about the use of fluoroquinolone antibacterial drugs in patients who have been diagnosed with the disease should contact their local or state tuberculosis control program, the CDC urges.

Prevention Parameters: 

Prevention may start with those who are infected with the disease who are latent. Those with latent infection and those who are identified as being in a high-risk group for contracting the disease should take medication to keep from developing the disease. Taking prescribed medicine as instructed can keep latent patients from developing the disease. 

All healthcare providers are encouraged to promote travel safety among all of their patients, who should avoid high-risk settings where there are lacking infection control measures. Documented places where transmission has occurred include crowded hospitals, prisons, homeless shelters, and other settings where susceptible persons come in contact with the disease, according to the CDC. Healthcare providers can also help to prevent XDR disease by diagnosing tuberculosis cases more quickly, following recommended treatment guidelines, monitoring patients’ response to treatment, and ensuring that all prescribed therapies are completed, according to the CDC. Providers should also promote and implement infection control procedures to prevent exposure to the disease in hospitals and other healthcare settings where tuberculosis patients are more likely to be seen.

References

  1. Tuberculosis (TB) Fact Sheet. CDC. 2016. Accessed online:  www.cdc.gov/tb/publications/factsheets/drtb/xdrtb.htm
  2. How TB Spreads. CDC. 2016. Accessed online: www.cdc.gov/tb/topic/basics/howtbspreads.htm
  3. FDA Drug Safety Communication: FDA Advises Restricting Fluoroquinolone Antibiotic Use for Certain Uncomplicated Infections; Warns About Disabling Side Effects That can Occur Together. FDA. 2016. Accessed online: www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-fda-advises-restricting-fluoroquinolone-antibiotic-use-certain

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