Combining Available XDR Tuberculosis Interventions Could Increase Effectiveness

Key Point

Nearly half of extensively drug-resistant tuberculosis cases could be prevented by combining currently available nosocomial infection control strategies.

The combination of available nosocomial infection control strategies could prevent nearly half of extensively drug-resistant (XDR) tuberculosis cases, according to a report published in the October 27 Lancet.

“Effective hospital-based strategies to limit the transmission of XDR tuberculosis are within reach, even in resource-limited settings,” Sanjay Basu, MSc, of Yale University School of Medicine in New Haven, and colleagues stated.

The researchers combined computer modeling with data from a multiyear epidemiological study to investigate the effect of administrative, environmental, and personal infection control measures on the epidemic trajectory of XDR tuberculosis in the rural town of Tugela Ferry, South Africa. The model simulated inpatient airborne tuberculosis infection, community tuberculosis transmission, and the effect of HIV and antiretroviral therapy. The model proved to be more than 95% accurate at estimating the course of the disease when evaluated against the latest data from South Africa.

They found that if no new interventions are introduced, roughly 1,300 cases of XDR tuberculosis could occur in the Tugela Ferry area by 2012; more than half of these cases would likely be transmitted within the hospital. Fewer than 10% of cases in the general epidemic would be prevented by the use of masks alone, but a large proportion of cases among hospital staff could be averted by mask use. Combined use of masks, reduced hospitalization time, and a shift to outpatient therapy could prevent nearly a third of XDR tuberculosis cases.

“Supplementing this approach with improved ventilation, rapid drug resistance testing, HIV treatment, and tuberculosis isolation facilities could avert 48% of XDR tuberculosis cases (range, 34% to 50%) by the end of 2012,” the investigators said.
However, they warned that lengthy hospitalization or involuntary detention in the absence of sufficient isolation facilities could increase the incidence of XDR tuberculosis, since the increased risk of nosocomial transmission outweighed the impact of decreased community-based transmission resulting from these policies. They concluded that their current projections highlight the need for immediate action in addressing the XDR tuberculosis epidemic.

As of May 2007, XDR tuberculosis has been reported in 37 countries and has been identified in all regions of the world. South Africa has had the largest cluster of XDR cases, with incidence in every region of the country. More than 200 cases have been reported from 40 sites in the KwaZulu-Natal province alone, the first 53 of which were in Tugela Ferry.

“Comprehensive programs should be rapidly implemented throughout KwaZulu-Natal and the rest of South Africa,” the authors stated. “Additional community-based strategies should also be developed in parallel, since hospital-based efforts alone might not fully curtail XDR tuberculosis transmission.”

In an accompanying editorial, Travis Por-co, PhD, of the University of California in San Francisco, and Wayne Getz, PhD, of the University of California in Berkeley, pointed out, “Multidrug and extensive drug resistance are monsters of our own creation. They might be with us longer than we think and might need us to spend more than governments or institutions are willing or able to pay.”           

Reference
Basu S, Andrews JR, Poolman EM, et al. Prevention of nosocomial transmission of extensively drug-resistant tuberculosis in rural South African district hospitals: an epidemiological modelling study. Lancet. 2007;
370(9597):1500-1507.
Porco TC, Getz WM. Controlling extensively drug-resistant tuberculosis. Lancet. 2007;370(9597):1464-1465.

Return to table of contents