Affiliation:
1. Sections of Clinical Microbiology
2. Infectious Diseases
3. Thoracic Imaging, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
Abstract
ABSTRACT
The clinical significance and prevalence of
Mycobacterium avium
and
Mycobacterium intracellulare
were analyzed in a cohort of 7,472 patients who, from 1999 to 2003, sought care at the University of Texas M.D. Anderson Cancer Center, Houston, and had cultures performed for mycobacteria. Patients were stratified for age, sex, and underlying diseases, and bacteria were identified by 16S rRNA gene sequencing.
M. avium
was isolated in 62 (0.83%) of 7,472 patients and
M. intracellulare
in 65 (0.87%). Clinically, only 10 of the 62 (16.2%) patients with
M. avium
had probable to definite evidence of infection, whereas the majority (83.8%) had weak evidence of infection. Sex and age did not affect the isolation or infection of
M. avium
. Hematological tumors predisposed to
M. avium
colonization but not infection. In contrast, 41 of the 65 (63.1%) patients with
M. intracellulare
had probable to definite infection, a level much higher than those with
M. avium
(
P
< 0.001).
M. intracellulare
was more prevalent in women (1.33% of 3,311) than in men (0.50% of 4,161) (
P
< 0.001), and underlying diseases had no effect in women. Men with lung cancer had a higher prevalence (1.37%) than men without (0.34%) (4.0-fold;
P
< 0.001), but it was similar to that in women. A marked age trend for the isolation of
M. intracellulare
among women was noted: 0.27% (1-fold) for ages of <50 years, 0.85% (3.1-fold) for ages 50 to 59 years, 1.50% (5.6-fold) for ages 60 to 69 years, and 3.74% (13.9-fold) for ages ≥70 years (trend,
P
< 0.001). The combined rate for women ≥50 was 1.86% (95% confidence interval [1.30 to 2.42%]) (6.9-fold). Together, these results suggest that, among non-AIDS patients,
M. intracellulare
is more pathogenic and tends to infect women increasingly beyond menopause (age ≥50 years) regardless of underlying disease. The prevalence rate of 1.86% in postmenopausal women suggests the need to further investigate the public health significance of
M. intracellulare
.
Publisher
American Society for Microbiology