Infections caused by extensively drug-resistant tuberculosis (XDR TB) leave patients and providers with limited treatment options. XDR TB only accounted for 63 cases of tuberculosis in the United States between 1993 and 2001, according to the National Tuberculosis Surveillance System. However, it is still quite contagious and can spread in airborne fashion like the general type of tuberculosis. Particularly vulnerable are patients living with HIV and other chronic immune-compromising conditions.
Related: Emerging Infectious Diseases: Strategies for Detecting and Preventing
Symptoms of extensively drug-resistant 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.
Causes and transmission of drug-resistant tuberculosis
Tuberculosis is caused by the bacterium mycobacterium tuberculosis, which can affect any part of the body but usually attacks the lungs. The disease may also impact the kidneys, spine, and brain. The bacteria spread through the air after an infected person coughs, speaks, or even sings. TB has the potential to be spread to anyone nearby if they breathe in the bacteria.
Tuberculosis bacteria cannot be transmitted via handshakes, food sharing, dirty surfaces, sharing a toothbrush, or kissing. Once someone is infected with the bacteria, the bacteria grows and spreads 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.) Not all infected people will become sick. However, the disease can prove to be fatal if not diagnosed and treated appropriately.
Extensively drug-resistant tuberculosis spreads in the same manner. It 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 for XDR tuberculosis
Tuberculosis in general is treated over a course of antibiotics over 6-9 months. XDR tuberculosis, however, is particularly difficult to treat. As the name suggests, it resists antibiotics isoniazid and rifampin, the two strongest tuberculosis drugs. It also resists antibiotics in the fluoroquinolone class and at least one of three injectable second-line drugs (i.e., amikacin, kanamycin, or capreomycin).
Some tuberculosis control programs have shown that a cure is possible for an estimated 30%-50% of affected people. 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.
Usually, tests can diagnose tuberculosis in 1-2 days following infection. However, 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. This may take 6-16 weeks.
Related: Antimicrobial Drugs: Pharmacology and Healthcare Considerations
Warnings and restrictions
XDR tuberculosis must be managed by or in close consultation with an expert. Inappropriate management can be life-threatening. The U.S. Food and Drug Administration (FDA) advises restricting fluoroquinolone antibiotic use for certain uncomplicated infections due to adverse effects from these medications. 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. It may also be necessary for who cannot tolerate first-line drugs. Healthcare providers who are unsure of or who have questions about the use of fluoroquinolone antibacterial drugs should contact their local or state tuberculosis control program, the CDC urges.
Prevention parameters for drug-resistant tuberculosis
Prevention starts with patients infected with a latent form of XDR TB. Those with latent infection and those 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 should promote travel safety among all of their patients. Patients 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.
Healthcare providers can also help to prevent XDR disease by diagnosing tuberculosis cases more quickly. They can follow recommended treatment guidelines, monitor patients’ response to treatment, and ensure that all prescribed therapies are completed. Providers should also promote and implement infection control procedures. This prevents exposure to the disease in hospitals and other healthcare settings where tuberculosis patients are more likely to be seen.
References
- Tuberculosis (TB) Fact Sheet. CDC. 2016. Accessed online: www.cdc.gov/tb/publications/factsheets/drtb/xdrtb.htm
- How TB Spreads. CDC. 2016. Accessed online: www.cdc.gov/tb/topic/basics/howtbspreads.htm
- 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
