Researchers validate a technique capable of quick TB diagnosis

Oct 7 2009

The team headed by Doctor Manuel Casal, head of Microbiology at Reina Sofia Hospital in Cordoba has validated in patients a technique, originally produced by a German company, capable of diagnosing tuberculosis in only one day and determining whether or not it is resistant to two of the drugs used to treat this disease. This Cordoba laboratory is considered by the Andalusian Government as a benchmark in the study of tuberculosis.

"Fast diagnosis is an important step towards eliminating this disease", affirms the head of the Microbiology Department at Reina Sofia Hospital, whose work group has validated a molecular biology genetics technique capable of detecting within a day, or at the most two, if a patient his suffering from tuberculosis and the mutations resistant to rifampicine and isoniazid, two of the drugs used in the treatment of this disease. "The longer a person suffers the disease without knowing it, the more people can be infected."

According to the Cordoba doctor, this technique does not search for live bacteria, but rather the most important component of these, the nucleic acid, within which a study is made of certain genes "that indicate a resistance mutation. In this way, directly and without having to resort to cultures, it is possible to test a patient suspected of suffering this disease. The test consists in the confrontation of a series of reagents with others, which tells us whether or not the pathology is present." Thanks to this system, "it is possible to obtain the test results the same day, while previous technique required at least 15 days."

At the moment this technique, validated by the doctors in Cordoba, is already being used in the large specialised laboratories of major hospitals and research centres with wide experience in this field.

From 15 days to one month for a diagnosis

Until now, tuberculosis resistances were detected using solid means - cultures of mycobacterium (Mycobacterium tuberculosis) growth - which took a month. Following the culture, the growth was confronted with different drug dilutions to determine whether or not the bacteria were sensitive or resistant to these. As Doctor Casal points out, this process is susceptible to contamination, test failure or contagion, meaning that it has to be carried out in security booths in laboratories.

Bacteria growth is also obtained on liquid mediums, which takes 15 days and also requires stringent security measures. This was the situation up until the introduction of this new technique, which has only one drawback -at the moment, it has only been tested using two of the five front-line drugs used to treat this disease. "Its use needs be extended to world-wide level and to the rest of the drugs."

Five front-line drugs are used to treat this disease, caused by Mycobacterium tuberculosis, with five secondary ones that are used in substitution of the first five when the patient shows resistance to these. It is spread via air from person to person and the minimum treatment lasts six months.