Acetic acid, an
active ingredient in vinegar, can be used as an inexpensive and non-toxic
disinfectant against drug-resistant tuberculosis (TB) bacteria, scientists say.
Acetic
acid can effectively kill mycobacteria, even highly drug-resistant
Mycobacterium tuberculosis, according to an international team of researchers
from Venezuela, France, and the US. Work
with drug-resistant tuberculosis bacteria carries serious biohazard risks.
Chlorine bleach is often used to disinfect TB
cultures and clinical samples, but bleach is toxic and corrosive, researchers
said. Other effective commercial disinfectants can be too expensive for TB labs
in the resource-poor countries where the majority of TB occurs, they said.
"Mycobacteria are known to cause tuberculosis and leprosy, but non-TB
mycobacteria are common in the environment, even in tap water, and are
resistant to commonly used disinfectants," said Howard Takiff, senior
author on the study and head of the Laboratory of Molecular Genetics at the Venezuelan Institute of Scientific
Investigation (IVIC).
While investigating the ability of non-TB
mycobacteria to resist disinfectants and antibiotics, Takiff's postdoctoral
fellow, Claudia Cortesia stumbled upon vinegar's ability to kill mycobacteria. Testing
a drug that needed to be dissolved in acetic acid, Cortesia found that the
control, with acetic acid alone, killed the mycobacteria she wanted to study.
"After Claudia's initial observation, we
tested for the minimal concentrations and exposure times that would kill
different mycobacteria," said Takiff. Collaborators Catherine Vilcheze and
William Jacobs, Jr at the Albert Einstein College of Medicine in New York
tested TB strains and found that exposure to a 6 per cent solution of acetic
acid for 30 minutes effectively kills tuberculosis, even strains resistant to
almost all antibiotics. In other words, exposure to 6 per cent acetic acid,
just slightly more concentrated than supermarket vinegar, for 30 minutes,
reduced the numbers of TB mycobacteria from around 100 million to undetectable
levels, researchers said. Takiff also tested how effective acetic acid was
against M abscessus, one of the most resistant and pathogenic of the non-TB
mycobacteria.
He found that M abscessus required exposure
to a stronger 10 per cent acetic acid solution for 30 minutes to be effectively
eliminated. The team also tested the activity under biologically 'dirty'
conditions similar to those encountered in clinical situations, by adding
albumin protein and red blood cells to the acetic acid and found it was still
effective. "There is a real need
for less toxic and less expensive disinfectants that can eliminate TB and
non-TB mycobacteria, especially in resource-poor countries," said Takiff. The
study is published in mBio, the journal of the American Society for
Microbiology.