Slow-growing TB bacteria point the way to new drug development

Mar 30, 2009

The discovery of a large number of slow-growing Mycobacterium tuberculosis bacteria, which cause tuberculosis (TB), in the lungs of TB patients could be an important step forward in the design of new anti-TB drugs.

Until now it was thought that M. tuberculosis bacteria in the lungs of TB patients were rapidly multiplying. However recent research by Dr Simon Waddell and colleagues from St George's University of London and the University of Leicester, using gene chips to look at how TB bacteria behave in different environments, revealed that the tuberculosis bacteria in the sputum (phlegm coughed from the lungs) of TB patients resemble bacteria that are growing very slowly or hardly at all. This has caused concern, as slowly growing bacteria are non-responsive to treatment with isoniazid, one of the main antibiotics used to treat TB. This may be the reason why it takes six months to treat pulmonary TB successfully, whereas most bacterial infections are treated in days. This prolonged treatment often leads people to stop taking their medicines early or only to take them intermittently, which can cause relapses and the emergence of antibiotic resistance.

"Our observations imply that either a large number of the infecting bacteria in the lungs are not multiplying rapidly as previously suggested; or the bacteria are adapting by not growing when they are coughed from the lungs into the air," said Dr Waddell, presenting his findings at the Society for General Microbiology meeting at Harrogate today (Monday 30 March).

"We need to find out how bacteria respond during infection and after drug treatment to understand how bacteria become tolerant to antibiotics. This will provide alternative opportunities for the development of better drugs that the world desperately needs to combat the growing health threat of TB."

Tuberculosis kills around 1.7 million people each year, equating to 4,500 deaths a day, or someone dying of TB every 19 seconds. Approximately one third of the world's population are infected with tuberculosis bacteria (~2 billion people), of which around one in ten will develop active disease. Current antibiotic treatment for M. tuberculosis involves a minimum of 3 drugs over a 6-month period (isoniazid, rifampicin and pyrazinamide for 2 months, followed by isoniazid and rifampicin for a further 4 months). Multidrug-resistant TB (MDR-TB), resistant to two front line drugs, and extensively-drug resistant TB (XDR-TB), resistant to at least two front line drugs and two others, have recently become major clinical problems. It is estimated by the WHO (World Health Organisation) that there are around 500,000 new cases of MDR-TB per year, and 40,000 new cases of XDR-TB. The need for new drugs to treat TB is greater now than ever.

Source: Society for General Microbiology

Explore further: Girls in Colombian town struck by mystery illness

add to favorites email to friend print save as pdf

Related Stories

Extensively drug-resistant tuberculosis found in California

Aug 13, 2008

In the first statewide study of extensively drug-resistant tuberculosis (XDR TB) in the United States, California officials have identified 18 cases of the dangerous and difficult-to-treat disease between 1993 and 2006, and ...

WHO: Money, drugs needed to rein in new TB strains

Mar 23, 2009

(AP) -- More money and better science are urgently needed to rein in new strains of tuberculosis that are tough or nearly impossible to treat, the WHO announced Monday in China, where the disease has long been a leading ...

WHO warns of drug-resistant TB

Sep 06, 2006

The World Health Organization in Switzerland has warned of a new strain of tuberculosis that is rapidly spreading and cannot be treated with current drugs.

Drug-resistant tuberculosis rife in China

Dec 11, 2008

Levels of drug-resistant tuberculosis (TB) in China are nearly twice the global average. Nationwide research published in the open access journal BMC Infectious Diseases has shown that almost 10% of Chinese TB cases are re ...

Recommended for you

Girls in Colombian town struck by mystery illness

2 hours ago

A mystery illness has overwhelmed a small town in northern Colombia as scores of teenage girls have been hospitalized with symptoms that parents fear could be an adverse reaction to a popular vaccine against cervical cancer.

Oral contraceptive equal to antibiotics for acne care

9 hours ago

(HealthDay)—At six months, oral contraceptive pills (OCPs) are comparable to systemic antibiotics for acne management, according to a review published in the September issue of the Journal of the American Ac ...

Photodynamic therapy vs. cryotherapy for actinic keratoses

10 hours ago

Photodynamic therapy (PDT, which uses topical agents and light to kill tissue) appears to better clear actinic keratoses (AKs, a common skin lesion caused by sun damage) at three months after treatment than cryotherapy (which ...

US official warns Ebola outbreak will get worse

12 hours ago

A third top doctor has died from Ebola in Sierra Leone, a government official said Wednesday, as a leading American health official warned that the outbreak sweeping West Africa would get worse before it ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Ashy
not rated yet Mar 30, 2009
Tuberculosis is Mycobacteria, it's unicellular, aerobic saprophyte eating only dead decomposing tissues. Certainly TB mycobacterias couldn't be killed by antibiotics.