The resistance of Mycobacterium tuberculosis and other mycobacteria of increasing clinical importance to chemical agents
Tuberculosis is a major public health problem which has been
compounded by the emergence of multi-drug-resistant strains of Myco.
tuberculosis (MDR-TB), an increased use of immunosuppressive therapy
and increasing numbers of HIV infection. To further complicate the
infection control issues, many of the environmentally associated
mycobacteria, commonly referred to as opportunistic pathogens, are
being incriminated in human infection with increasing frequency.
Information is required on the mycobactericidal effectiveness of
disinfectants, especially those associated with heat sensitive
equipment such as bronchoscopes, which may be contaminated with
mycobacteria. The activity of disinfectants against Myco. tuberculosis
is well documented. However, there is much variation in test
methodology resulting in conflicting efficacy data. Therefore a
standard, reproducible and practical method must be developed which
will give useful and reliable data on the resistance of Myco. tuberculosis
and other mycobacteria of increasing clinical importance to current
A standard test method was developed for use in this study.
Suspension and carrier tests were carried out in the presence and
absence of 10% serum as the organiC load. The test organisms were
type strains of Myco terrae, Myco chelonae, Myco. fortuitum and Myco.
tuberculosis. 1\vo endoscope washer disinfector isolates of Myco.
chelonae and a clinical isolate of Myco. avium-intraceUulare were also
used. The type strains of Myco. chelonae and Myco. fortuitum were very
sensitive to all disinfectants tested. My co. terrae was slightly more
resistant than Myco. tuberculosis. This is in agreement with published
data. Myco. avium-intraceUulare was without doubt the most resistant
of all the test organisms. The two machine isolates of Myco. chelonae
were extremely resistant to 2% glutaraldehyde. This prompted further
work to assess if these two strains differed from the type strain in