Aids Weekly Plus
A report in The Journal of Infectious Diseases states that an epidemic of extensively drug-resistant tuberculosis (XDR TB) in Tugela Ferry, South Africa, is the result of interconnectedness that has allowed several generations of nosocomial transmission. Neel Gandhi, MD, associate professor of epidemiology at the Rollins School of Public Health at Emory University in Atlanta, Ga., explains that “rather than an isolated outbreak that can be traced back to a single index case, conditions in South African hospitals are allowing for multiple generations of transmission, which in turn allows for the propagation and expansion of the epidemic.” He goes on to note that without a comprehensive plan for infection control within the hospitals, it will be a challenge to control the current epidemic.
From 2005 to 2009, Tugela Ferry recorded 516 diagnosed cases of XDR TB, with most of the patients being infected with HIV as well. Due to the similarities between this outbreak and outbreaks of multidrug-resistant TB in the 1990s, researchers decided to examine the role of nosocomial transmission in the current epidemic.
Researchers conducted an observational study of patients diagnosed with XDR-TB from 2005 to 2006, reviewing medical records, identifying epidemiological links between patients, genotyping the TB isolates, and determining the method of transmission. Their findings revealed that 98 percent of the 148 study participants were co-infected with XDR TB and HIV, and 93 percent were hospitalized while infectious. Before their XDR TB diagnosis, 113 of the patients were hospitalized at least once, and 80 of the 113 were exposed to at least one patient infected with XDR TB. Genetic analysis demonstrated that one predominant cluster, ST60, accounted for 92 percent of the isolates and the KZN strain made up 96 percent of the ST60 cluster isolates. The researchers were able to establish an epidemiologic link for 42 out of 51 patients in the ST60/KZN cluster. These patients demonstrated a high degree of interconnectedness, with as many as three generations of transmission among men and five generations of transmission among women.
Gandhi notes that, in addition to examining transmission of XDR TB within hospitals, the researchers have expanded their investigation to include community settings such as schools, bars, and churches to better understand whether genetic alterations are occurring that may allow XDR TB to become more transmissible.
The study, “Nosocomial Transmission of Extensively Drug-Resistant Tuberculosis in a Rural Hospital in South Africa,” was published in the Journal of Infectious Diseases (2013; 207(1):9-17).