O P KAPOOR
The incidence of tuberculosis has declined since 2004, but only by less than 1% per year. Case detection is stagnant.
More worrying is the synergy of tuberculosis and HIV/AIDS co-infection in sub-Saharan Africa, and the growth of multi-drug-resistant tuberculosis (MDR-TB) and extensively drug-resistant strains (XDR-TB) in eastern Europe and two factors that complicate treatment and threaten to increase fatality rates.
India and China have the world’s largest burden of incidence of tuberculosis, 2 million and 1.3 million people, respectively and both have over 100,000 people with MDR-TB.
In 2004, WHO urged more collaboration between HIV and tuberculosis programmes, with routine testing for HIV in people with tuberculosis in people with HIV/AIDS.
Only 2% of the estimated 500,000 people infected with drug resistant strains were tested in 2007. And even when diagnosed with this more lethal form of tuberculosis, fewer than 3% received treatment recommended by international guidelines.
Shorter treatments improved compliance and increased efficiency. But more development in diagnosis and treatment is needed.
I am happy to note that at the time of releasing this Golden Jubilee issue of BHJ, the good news is – fluoroquinolones were found to have activity against M tuberculosis and would become the first real competitors of the two most powerful classes of antituberculosis agents that are now in routine use. Although, nearly all fluoroquinolones have antimycobacterial activity, the fourth generation, which includes gatifloxacin and moxifloxacin, have particularly strong activity against M tuberculosis.
Ethambutol does not enhance, or only minimally enhances, the activity of the combination of isoniazid, rifampicin and pyrazinamide against a fully susceptible strain. Indeed, so far, no drug has substantially enhanced the activity of this three drug combination. The trial’s finding that culture conversion to negative occurred in 80% of patients in the moxifloxacin group compared with 63% in the control group is, therefore, surprisingly large.
There is a suggestion that moxifloxacin (and probably gatifloxacin) has the potential to shorten the treatment for tuberculosis.
However, it remains to be seen whether fourth-generation fluoroquinolones will allow tuberculosis treatment to be shortened.
Fourth-generation fluoroquinolones probably have similar bacterial activity and might exceed the sterilizing activity of isoniazid.
In other words, multi-drug resistant (M.D.R) tuberculosis (resistant to isoniazid and rifampicin) that is not (X.D.R) extensively drug resistant (additionally resistant to the fluoroquinolones and injectable drugs other than streptomycin), should no longer be complex to treat.