A medical doctor from Stellenberg almost went deaf from TB medication after contracting the dreaded multi-drug resistant (MDR) strain of the disease.
Now she is advocating for cheaper, safer new antibiotics for TB treatment through TB Proof, the NGO she now works for.
“I didn’t lose my hearing completely,” Dr Dalene von Delft told TygerBurger.
“The TB medication that causes hearing loss is an antibiotic we use to treat MDR TB,” she said.
This strain of the bacteria causes the same disease as “regular” TB, but Dalene explains it is resistant to first-line antibiotics because it has become mutated.
Dalene contracted MDR TB through her work in 2010. Because the bacteria is airborne, inhaling it causes the majority (up to three quarters) of MDR cases in the country.
“We are currently using a very old regimen of medication with a very old combination of drugs for treating MDR TB,” she said.
This usually consists of six or seven different kinds of antibiotics – including a group of antibiotics called the aminoglycosides – used to treat different types of bacterial infections.
“These antibiotics are widely used; they are ‘old’ drugs which have been in use since the 1950s. It is still frequently used in hospitals, but for short periods, usually less than two weeks. In MDR TB one has to use it long term,” she said.
The World Health Organisation’s (WHO) guidelines recommended treatment with aminoglycosides for MDR TB for eight months, with total treatment lasting up to two years.
“Unfortunately one of the side-effects is hearing loss.” Some of the antibiotics from the aminoglycoside class most frequently used in South Africa are kanamycin and amikacin, Dalene said.
“Because these drugs are already 60 years old, their patents have long expired and they’re very cheap and made by different manufacturers,” she said.
“Yes, it comes with a warning that it could cause hearing loss, but it’s not like you can sue the drug company, because it is used ‘off-label’. This means the drug companies do not recommend long term use of these drugs for the treatment of MDR TB, but doctors are forced to use these drugs as there are no alternatives, and it is a deadly disease,” Dalene said.
The WHO recommends regular screening for hearing loss by means of audiograms,” she said, explaining this meant hearing at different frequencies and amplitudes.
“We don’t understand how it causes hearing loss, but it affects the nerve responsible for hearing – the cochlear nerve – and the outer hair cells which pick up high frequency tones, are affected first,” she said.
“Low tones still sound okay for patients, but they start struggling with consonants ‘f’, ‘s’, ‘k’, ‘p’, ‘t’. They might not pick up high soprano notes.
Studies estimate that about one third of MDR patients lose their hearing, Dalene said. And there are no alternatives.
“You either become deaf or dead. In most cases you cannot stop the old treatment even though you might lose your hearing.”
So when Dalene learnt these were her only two choices, she tried to access a new drug being tested in South Africa.
“I didn’t want to accept that. If I became deaf, I wouldn’t be able to listen to music or conversations anymore; I wouldn’t be able to practice as a doctor anymore,” she said. She spoke to people who have had cochlear implants, Dalene said, one of them a nurse who contracted MDR TB and had the implant done, but still had trouble using a stethoscope.
“I realised this was a career ending situation. Week after week it just got worse. My hearing deteriorated. Then I heard of a new drug – the first new TB drug in 40 years,” she said.
Janssen pharmaceuticals (part of Johnson andamp; Johnson) were doing clinical trials in Cape Town on a drug called Bedaquiline, offering a slim chance of hope.
“Treatment of MDR TB has been at a dead end until recently.”
She found out about the new drug and contacted the principal investigator and tried to get the drug available on compassionate use. “Sometimes they make new drugs available before the clinical trials are completed, seeing as these can take years and years. It already took about 25 years to develop Bedaquiline.
“We are very lucky. So far small studies suggest that this new drug is effective and there’s a chance it might replace the old drug,” she said.