TB Transmission in Healthcare Settings
In all the news and hype about the cases of extensively drug resistant tuberculosis (XDR-TB) in KwaZulu Natal, South Africa, there has been surprisingly little discussion about how and where many of the people acquired the XDR-TB infections.
"The evidence, I think, clearly points to nosocomial transmission of a very lethal organism," said Dr. Gerald Friedland of Yale University during a symposium on Infection Control at the recent 37th World Union on Lung Health Conference in Paris. Dr. Friedland collaborates with the researchers in KwaZulu Natal, South Africa who reported the cases of XDR. (Nosocomial means an infection or disorder acquired in hospital).
Dr. Anthony Moll was the clinician at the 350-bed district hospital in Tugela Ferry, South Africa, who first detected what would turn out to be XDR-TB in a subset of his TB patients. The hospital serves a rural district with a very high prevalence of TB: a case rate of 800 to 1,000 per 100,000 individuals, and 70-80% of the cases are HIV co-infected.
Dr. Moll was running a novel TB/HIV integration study offering treatment and care for both diseases in coinfected patients (with family members offering adherence support) in which the majority of patients were doing extremely well -- but he noticed an unusually high and rapid mortality rate in a subset of 14 patients. Ten of these were found to have MDR- and eventually XDR-TB (6 in newly treated patients and 4 in patients who had successfully completed a course of treatment).
"The rate of MDR in newly treated cases in the study was 9%" said Dr. Friedland. This was four times the rate of MDR-TB that had been reported in the last prevalence survey five years previously.
So they decided to perform a local clinical and mycobacterial survey (with drug sensitivity testing) which included three groups: 1) all the recent treatment failures and retreatment cases, 2) the in-patients in TB wards and 3) TB suspects presenting to the district hospital with TB symptoms. The survey included a total of 1539 patients, 544 of whom were culture positive, 221 (41%) of whom had MDR-TB and 53 of whom were XDR-TB.
Although MDR-TB appeared to be endemic in the area -- and XDR-TB is a natural by-product of inadequately diagnosed and treated MDR-TB -- 26 (55%) of the 53 people identified with XDR-TB turned out never to have been treated for TB before.
A chart review, which included demographics, prior TB, and prior hospital admissions, was performed for the people with XDR-TB but failed to reveal anything that linked all these subjects together, except that two-thirds of them had been hospitalized within the past two years-and all 53 had used the same district hospital on either an in- or outpatient basis. Also telling was the fact that contact tracing identified no additional cases in the community, and DNA fingerprinting suggested that 85% of the isolates were genetically similar.
"Looking at previous TB treatments and previous hospitalization, putting all of that together gave us the idea that we were looking at nosocomial spread of XDR-TB," said Dr. Moll.
Transmission to People With HIV
But what's particularly distressing is that the hospital at Tugela Ferry was the very first in the province to offer antiretroviral therapy, and thus it has served as a magnet to people with HIV in the area. Forty-four of the 53 were documented as HIV-positive and would have been receiving their HIV care from the hospital.
"This whole issue obviously raises the problem of tuberculosis transmission in congregate settings in hospitals," said Dr. Kevin de Cock, Director of the WHO Department of HIV/AIDS, in another session of the conference. "We are congregating patients for ARV services in hospitals where infection control has been neglected over the years."
"Transmission of MDR and XDR-TB really must be addressed to further improve survival for HIV co-infected patients," said Dr. Friedland. "I would say quite ominously that in high-prevalence areas, the success of both antiretroviral therapy and TB-DOTS programs is really threatened by the presence of MDR and XDR TB."
Indeed if people perceive that waiting rooms and in-patient facilities are dangerous places (and in many situations, they clearly are), it could significantly impact on health-seeking behavior.
Excerpted from a report in HIV & AIDS Treatment in Practice (HATIP) #79, December 19, 2006.