Multidrug-Resistant Tuberculosis Tuberculosis is an airborne infectious disease caused by tubercule bacilli, spread from person to person (CDC 2011). It affects the lungs and other parts of the body, such as the brain, the kidneys and the spine. It is curable but an infected person can also die of it if he does not get proper treatment (CDC)

MDRTB

Multidrug-resistant tuberculosis or MDRTB is TB that does not respond to the action of at least two of the best drugs, isoniazid and rifampicin, the first-line treatment of TB (CDC 2011). Extensively drug-resistant TB or XDRTB is the rare type, which is resistant to these two major drugs, to any fluoroquinolone and at least one of three injectable second-line drugs. These injectable drugs are amikacin, kanamycin and capreomycin. These additional drugs are considered second-line treatment for TB. Those with XDR TB resort to less effective options. Among those affected are persons with HIV or other infections, which weaken the immune system. They are more disposed to TB and have a higher risk of death from TB. MDR TB spreads in the same way as TB, which is by coughing, sneezing, speaking or even singing. MDR TB germs remain in the air for several hours, depending on the environment. Those who breathe the air where these germs are suspended can inhale them and get infected (CDC).

Anti-TB Drug Resistance, MDR TB Prevention

Resistance to anti-TB drugs results from their wrong use or management (CDC 2011). This can occur with incomplete course of treatment, wrong treatment, wrong dose, long duration, unavailability of the drugs, or poor quality of the drugs. This is more likely in persons who do not take their TB medicines regularly or omit them as instructed by their doctor or nurse. TB can reactivate in them even after TB medicines if they come from places where MDR TB is common or prevalent (CDC).

MDR TB can be preventing by taking medications exactly as directed and without missing a single dose (CDC 2011). Travelers with this sickness should make sure they have enough medications to last their trip. Prompt diagnosis will help prevent the spread or worsening of the condition. The patient should follow recommended guidelines. Health care providers should monitor patient response and completion of therapy. Another prevention is avoiding exposure to those already infected or suspected of being infected. Crowded and likely places should be avoided as much as possible, such as hospitals, prisons and shelters for the homeless. A vaccine called Bacille Calmette-Gurin is used for children in some countries but not generally recommended in the United States for its limited effectiveness. Those who are exposed to persons with the disease should get a TB skin or blood test (CDC).

TB Control in the 21st Century

The TB outbreaks in the U.S. In the late 80s and 90s spurred the use of massive resources that would insure safe workplaces (Sepkowitz 2001). This greatly decreased the transmission and actual cases nationally. Federal standards were established to insure a working environment free of the bacilli for U.S. workers exposed. This measure may, however, be costly and detrimental to the delivery of care (Sepkowitz).

It was only in the 50s and 60s that the risk of exposure to TB among health workers caring for patients became a concern (Sepkowitz 2001). The discovery that the infection is air-borne was new at the time and caught little attention. Outbreaks of TB and MDR TB in the 80s and the 90s in U.S. And European hospitals called the attention it lacked. More than 20 health care workers got infected with MDR TB and at least 10 of them died. Hundreds of them may have remained carriers and pose serious risk of future activation of the illness. These outbreaks have been substantially controlled but their consequences persist and can still be felt. One consequence is the confusion on which of the many interventions are still effective. In addition, current control measures continue to bank on the outdated PPD test and the insensitive sputum AFB smear. Reliance on these inadequate diagnostic tests is unlikely to improve gains in TB control. As far as can be gleaned, TB control will lean on the low-tech measures of isolation of potential or suspected persons, masks, and shutting doors of potential patients in hospitals (Sepkowitz).

Extensively Drug-Resistant Tuberculosis

The first 74 cases of this new type were first reported in November 2005 by the U.S. National TB Surveillance System (Morbidity & Mortality Weekly 2007). The World Health Organization Emergency Global Task Force in October 2006 came up with a new definition of XDR TB. It is resistance to at least isoniazid and rifampin among the first-line anti-TB drugs, any fluoquinolone and at least one injectable...

After approximately 30 years of decline, TB epidemic increased between 1985 and 1992 with more than 22,000 cases in 1985 rising to more than 26,000 in 1992. While still largely unknown before 1993, numerous outbreaks of MDRTB already occurred in the late 80s and early 90s. The 1992 National Action Plan to Combat MultiDrug-Resistant Tuberculosis quickly reduced the incidence by improving laboratory services and infection control and strengthening National TB Surveillance System tests starting in 1993. These improvements appeared to account for the rapid 34% decrease in overall TB cases from 1993 to 1999 in the United States. Comparison with 2000-200 cases showed that XDR-TB had an overall decrease in incidence among HIV-infected persons, an in increase among foreign-born persons, and an increase among Asians with XDR-TB (Morbidity & Mortality Report).
Effective treatment of MDRTB requires 18-24 months of 4-6 drugs to which the person is susceptible, including multiple second-line drugs (Morbidity & Mortality Report 2007). The use of second-line drugs went up substantially with the treatment of increasing number of cases starting in the 80s by physicians and TB-control programs. This increased use produced MDRTB strains extensively resistant to both first-and-second-line drugs (Morbidity & Mortality Report).

Epidemiology

Close to 500,000 or 5% of all new cases of TB diagnosed in 2006 were MDRTB, as they were resistant to isoniazid and rifampicin (Mitnick et al. 2008, Mortality & Morbidity Weekly 2006). This reflected a 12% increase over the 2004 incidence and 56% over 2000. About 1-1.5 million more cases surfaced in 2006, bringing to 2 million the number of those actively afflicted. The treatment of MDRTB consists of second-line drugs, which are too costly for those in resource-poor settings. The World Health Organization addressed the shortage by creating the Green Light Committee in 2000, which would make second-line agents accessible to these settings and strictly supervise their use. A significant decrease in incidence was achieved by the Committee. However, drug-resistant TB continues to grow and create trouble in most settings. The seriousness of the problem and the increase in related illnesses and deaths prompted a proportionate increase in research and scaled-up treatment. Some studies explored the molecular mechanisms of resistance, risk factors for drug-resistant TB and HIV, and global epidemiology of TB (Mitnick et al., Morbidity & Mortality Weekly).

The estimated burden of MDRTB is significant enough to call for concerted action (Mitnick et al. 2008, Morbidity & Mortality Weekly 2006). All appropriate interventions require scale-up of laboratories and early treatment containing enough second-line drugs. Ambulatory treatment and improved infection control will facilitate scale up by reducing the risk of nosocomial transmission. Obstacles to worldwide scale-up of treatment mostly point to inadequate human, drug, and financial resources. Increased delays can enhance risk of continued transmission of resistant TB and associated illnesses and deaths (Mitnick et al., Morbidity & Mortality Weekly).

Molecular Epidemiology

Outbreaks in the 80s and early 90s in New York City caused widespread transmission of MDRTB strains in hospitals and state prisons (Munsiff et al. 2002). The W. strain was identified in the outbreaks. This strain is resistant to isoniazid, rifampin, ethambutol, and streptomycin and, often, also kanamycin. Surveys later showed the presence of the same strain in New York City, suggesting recent transmission. An enhanced Tuberculosis Control Program in 1992 reduced the number of TB cases by 21% in 1994 and MDRTB by 60%. No documentation of outbreaks have been undertaken in the City since then (Munsiff et al.).

The New York City Tuberculosis Control Program conducted DNA genotyping of MDRTB strains for new cases from 1995-1997 to better understand the occurrence, transmission and control of MDRTB (Munsiff et al. 2002). MDRTB was diagnosed in 241 patients, 217 or 90% of whom had not had treatment and 166 or 68.9% born in the United States or Puerto Rico. MDRTB patients are more likely to be born in the United States, have HIV infection and work in the health care sector. Of this number, 30 or 12.8% were likely exposed to and contaminated by those afflicted during the outbreaks in the early 90s in the City. These patients appeared to have more bacilli and thus more infectious.

It was possible that many of those infected were already with HIV during the outbreaks. MDRTB progresses much faster in HIV-infected patients than in non-HIV patients. These highly resistant strains transmitted in the late 80s and early 90s were…