"No windows and five or six people to a room," she said. "Not enough light and no ventilation - 70 to 80 per cent of our patients live like this."
MDR-TB does not respond to the two most powerful TB drugs available, so patients must take a cocktail of up to 30 tablets a day, MSF staff said at a media event in a Nairobi slum ahead of global World Tuberculosis Day on Saturday.
The extra medicines cause vomiting, diarrhoea and severe depression in many cases, they said.
Tuberculosis, which kills an estimated 1.5 million Africans a year, is spread through the air like the common cold, and health workers say poor ventilation and lack of sunlight dramatically increase infection rates.
"When our classical treatment for TB fails, we have to treat for MDR-TB using drugs developed nearly 50 years ago," Genevier said.
About 45 per cent of patients who undertake the 18- to 24-month programme do not live to complete it, MSF said in a report.
The World Health Organisation estimates that there are up to 1.5 million cases of MDR-TB in the world today, with 420,000 new infections and 116,000 deaths a year.