SciDev.Net

Examining cultures of TB mycobacteria for signs of drug-resistance

WHO/TDR/Crump

An antibiotic used to combat multidrug-resistant tuberculosis in children could be leading to resistance to a similar drug in an unrelated bacterium that causes pneumococcal disease, say researchers.

The authors of the study, published in The Lancet last week (24 March), say that this problem should be taken into account by health policymakers trying to prevent the spread of drug-resistant Streptococcus pneumoniae. 

The researchers assessed 21,521 cases of invasive pneumococcal disease — including pneumonia, blood poisoning and meningitis — from routine microbiological surveillance data collected by South Africa's National Health Laboratory Service between 2000 and 2006.

They discovered that 12 children who had been infected with Streptococcus pneumoniae were resistant to treatment with a drug called levofloxacin, a member of the fluoroquinolone group of drugs used to treat multidrug-resistant tuberculosis.

Eighty-nine per cent of these children had previously been treated with fluoroquinolone for tuberculosis. Most of the children had acquired the pneumococcal infection while in hospital.

"This is big news," says Anne von Gottberg, co-director of the Respiratory and Meningeal Pathogens Research Unit at the National Institute for Communicable Diseases in South Africa.

"The problem is that the children receiving treatment for drug-resistant TB can spread the pneumococcal bacteria — now also drug-resistant — to the wider community."

"Adults — especially the elderly or people with compromised immune systems — will be at risk if the drug-resistant form of the bacteria spreads, because treatment for pneumonia may fail."

The results highlight the importance of the National Health Laboratory Service's constant routine disease surveillance, says Nelesh Govender, a pathologist at the service and co-author of the paper.

''We wouldn't have had an inkling of this problem if we didn't have a very good lab-based surveillance system in place where we monitor for drug resistance,'' Govender says.

As a short-term measure, the researchmay boost efforts to roll out more pneumococcal vaccines, seldom available in most African nations, specifically for children in hospital with multidrug-resistant tuberculosis, Govender says.

Link to full paper in The Lancet*

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