The aim of this study was to determine the prevalence of
non-tuberculous mycobacteria (NTM) isolates at University Hospital, Reference
Center for Aids in Rio de Janeiro, Brazil, during one year. We used standard
biochemical tests for species identification and IS1245 PCR amplification
was applied as a
Mycobacterium avium
specific identification marker. Four hundred and four specimens from 233
patients yielded acid-fast bacilli growth.
M. tuberculosis
was identified in 85% of the patients and NTM in 15%. NTM disseminated infection
was a common event correlated with human immunodeficiency virus (HIV) infected
patients and only in HIV negative patients the source of NTM was non sterile
site.
M. avium
complex (MAC) was biochemically identified in 57.8% (49/83) of NTM isolates,
most of them from sterile sites (75.5%), and in 94% (46/49) the IS 1245
marker specific for
M. avium
was present. Twenty NTM strains showed a MAC biochemical pattern with the
exception of a urease-positive (99% of MAC are urease-negative), however
IS1245 was detected in 96% of the strains leading to their identification
as
M. avium
. In this group differences in NTM source was not significant. The second
most frequently isolated NTM was identified as
M. scrofulaceum
(7.2%), followed by
M. terrae
(3.6%),
M. gordonae
(2.4%),
M. chelonae
(1.2%),
M. fortuitum
(1.2%) and one strain which could not be identified. All were IS1245 negative
except for one strain identified as
M. scrofulaceum
. It is interesting to note that non-sterile sites were the major source
of these isolates (92.8%). Our finding indicated that
M. avium
is still the major atypical species among in the MAC isolates recovered
from Brazilian Aids patients without highty active antiretroviral therapy
schema. Some discrepancies were seen between the identification methods
and further investigations must be done to better characterize NTM isolates
using other phenotypic and genotypic methods.
