Time to Review Your Hospital Tuberculosis Control Plan: Updated CDC Guidance

This is a guest post by Jorge Salinas, MD, Hospital Epidemiologist at University of Iowa Hospitals and Clinics.

The National Tuberculosis Controller Association (NTCA) and the Centers for Disease Control and Prevention (CDC) just published their updated guidance for the prevention of M. tuberculosis (TB) transmission in healthcare settings.

The previous guidelines (2005) called for tuberculosis screening for all healthcare workers upon hire and yearly if working in medium-risk settings. The setting risk was calculated based on the number of TB cases seen in the previous year. While most United States Hospitals were considered low risk, many large academic medical centers and hospitals in states with a higher incidence of TB were considered medium-risk. Fortunately, a number of studies performed in developed settings show that the rate of latent TB infection among healthcare workers is not different than the general population. In the updated guidance, hospitals previously considered medium-risk would continue testing upon hire but discontinue yearly TB screening (tuberculin skin testing or interferon gamma-release essay). This recommendation is welcomed as employee health resources can then be allocated to other emerging concerns (e.g., maximizing immunizations among healthcare workers).

The new guidance does not reduce the requirement for fit testing likely because the current TB infection prevention measures (administrative and environmental controls and personal protective equipment use) are likely the reason for such low levels of TB transmission among healthcare workers. As more data is gathered, next research steps could involve studying the necessary frequency of fit testing or the best method used (qualitative or quantitative methods).

These new recommendations will need to be accompanied by adequate contact investigations in healthcare settings. In the past, even if some contacts were not identified, the routine yearly screening would detect those patients within one year of the exposure. Now, an unidentified contact could go unnoticed until TB disease occurs. This increases the importance of training and knowledge of TB contact investigations in healthcare settings. However, TB contact investigations in healthcare settings are not straightforward: healthcare workers may have baseline positive skin testing and it is difficult to quantify the exposure risk (there is no standard recommended threshold for distance from patient or duration of exposure). Even if there was a recommended threshold, it would likely vary depending on other factors such as patient infectiousness (cavities, smear positivity) and healthcare worker immune status. Out of caution, healthcare workers may also tend to overreport exposures potentially overwhelming infection prevention programs. Another unique aspect of TB in healthcare settings involves extrapulmonary TB. Although in public health settings extrapulmonary TB is deemed likely not transmissible, it may lead to exposures in healthcare settings, especially during wound care, or procedures that may generate aerosols or splashes (irrigation, or bone surgery).

Congratulations and thank you to NTCA and CDC for their updated recommendations in light of new evidence. Those on the frontlines (Employee Health and Infection Prevention programs) will be able to reallocate resources and put their TB contact investigations skills to test.

Good riddance?

This week we suspended our tuberculin skin test program for healthcare workers due to the nationwide shortage of tuberculin. I say, Glory Hallelujah! I can't think of a more poorly performing test. Really, it's junk. And we've reached a point at our hospital that no healthcare worker will take isoniazid after a positive skin test until an interferon-gamma release assay has been done and is positive. However, there doesn't appear to be a good correlation between the skin test and the IGRA, so when the two tests are discordant, it's a coin toss as to which is the true result. To complicate matters even more, there's also a nationwide shortage of isoniazid. And don't even get me started on the use of isoniazid to treat latent TB (see here).

Photo:  Mayo Clinic

Baltimore Hooters' waitress contracts...TB?

The Baltimore Sun Paper reports that a 19-year old worker at the Inner Harbor Hooters contracted TB from a co-worker. Since that time she has been under quarantine and subject to directly observed therapy. Per the article: "multiple other members of the Hooters staff were confirmed to have latent or nonactive tuberculosis after the restaurant and the Health Department scheduled two separate testings for staff at downtown hotels last October and in March."

Still, I think you should plan your trip to Baltimore.  The Inner Harbor is beautiful in June and the Orioles are in first place. And on the plus side in this case, the woman was awarded workers' compensation from Hooters to cover lost wages and mounting medical expenses and Baltimore TB cases continue to decline with about 32 cases/year down from 60 in 2001. Back those bags and head to Charm City.

h/t Dan Morgan

So just how evil is INH?

A recent issue of MMWR has a report of 17 cases of severe liver injury occurring in persons being treated with isoniazid (INH) for latent tuberculosis. Five of these patients required liver transplantation, and five died. Of note, all patients were monitored for toxicity in compliance with guidelines. These cases were detected via a passive surveillance system. I suspect that this is just the tip of the iceberg since as I have blogged before, I have personally seen 3 cases in the last few years (two died, one survived after liver transplantation). In addition, less than half of patients complete the 9-month recommended course of therapy. On the other hand, only a small percentage of those treated develop severe liver injury, since it is estimated that 300,000-400,000 are treated with the drug each year. Still, I continue to believe that this drug is simply too toxic to treat a latent infection which has on average only a 10% chance of converting to active disease. Certainly some patients are at much higher risk for developing active tuberculosis, but those patients are also often at higher risk of toxicity. For those clinicians who feel compelled to use it, I would recommend careful informed consent and monitoring of transaminases for all patients, not just those for whom testing is recommended by the ATS/CDC guideline.

Treatment of latent tuberculosis: efficacy vs effectiveness

I've blogged before about the poor options we have for treating latent tuberculosis. The standard regimen, 9 months of isoniazid (INH), is too long and too toxic for the treatment of tuberculosis that is not active. For patients that aren't immunosuppressed and not recent skin test converters, the risk for developing active tuberculosis is only about 5%. Though the data for efficacy are not as robust, the 4-month daily rifampin regimen is much easier and better tolerated, and I have become more comfortable with this regimen. Because of the referral nature of my practice, the patients referred to me for evaluation of latent tuberculosis often have elevated liver enzymes at the outset or may not want to wait 9 months to complete the standard regimen before starting a therapy they feel is important (e.g., TNF-alpha inhibitors or other immunosuppressants).

A new study reported in this month's Chest examines completion rates of latent TB treatment courses. The investigators found that less than half of persons started on a treatment course actually finish it. About 45% complete a 9-month course of INH, 55% complete a 6-month course of INH, and nearly 65% complete the 4-month rifampin regimen. This leads me to wonder: even if 9 months of INH were ultimately proven to be more efficacious, perhaps 4-months of rifampin is more effective. Efficacy refers to how well a therapy works under ideal conditions (i.e., you take all the doses as prescribed), whereas effectiveness refers to how well a therapy works under real-world conditions (i.e., how well does the drug work when compliance is factored in). Given the toxicities of INH and the longer duration of treatment, coupled with the results of this survey, it's not far-fetched to conclude that what is considered our most efficacious regimen for latent tuberculosis may be our least effective.

When the treatment is worse than the disease

The University of Missouri Health Care System is re-evaluating its current policy on healthcare workers with latent tuberculous infection, which currently encourages but does not mandate treatment. The impetus for the review is a healthcare worker who had tested positive for latent tuberculosis via positive skin testing many years ago but declined to be treated, and recently developed active disease, exposing over 200 persons to tuberculosis. I suspect that most hospitals have similar policies and am not aware of a hospital that either prohibits those with latent but untreated infection from working or mandates treatment of latent tuberculosis. By definition, latent tuberculosis is not contagious but every person with latent infection has a small chance of developing active infection, which is contagious.

Isoniazid (INH), the standard drug used to treat latent tuberculosis given daily for nine months, is not an innocuous drug. In just the past few years, I have seen two deaths (both persons in their early 40s) and another healthy man who required a liver transplant due to the liver toxicity caused by the drug. Thus, I believe the drug is too toxic to require latently infected healthcare workers to be treated. Like the vast majority of healthcare workers, I have a TB skin test placed yearly. But I have decided that should my skin test convert to positive, I would not take INH because I believe it is too dangerous. We sorely need safer drugs for this condition. And we need better tests to detect latent tuberculosis--those currently available have many false positives and false negatives.