Genetic diversity of Mycobacterium avium isolates recovered from clinical samples and from the environment: molecular characterization for diagnostic purposes.
Isolation of Mycobacterium avium complex (MAC) organisms from clinical samples may occur in patients without clinical disease, making the interpretation of results difficult. The clinical relevance of MAC isolates from different types of clinical samples (n = 47) from 39 patients in different sections of a hospital was assessed by comparison with environmental isolates (n = 17) from the hospital. Various methods for identification and typing (commercial probes, phenotypic characteristics, PCR for detection of IS1245 and IS901, sequencing of the hsp65 gene, and pulsed-field gel electrophoresis) were evaluated. The same strain was found in all the environmental isolates, 21 out of 23 (91.3%) of the isolates cultured from urine samples, and 5 out of 19 (26.3%) isolates from respiratory specimens. This strain did not cause disease in the patients. Testing best characterized the strain as M. avium subsp. hominissuis, with the unusual feature that 81.4% of these isolates lacked the IS1245 element. Contamination of certain clinical samples with an environmental strain was the most likely event; therefore, characterization of the environmental mycobacteria present in health care facilities should be performed to discard false-positive isolations in nonsterile samples, mainly urine samples. Molecular techniques applied in this study demonstrated their usefulness for this purpose.
Alvarez
Julio
J
Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain. alaranaz@vet.ucm.es
García
Ignacio Gómez
IG
Aranaz
Alicia
A
Bezos
Javier
J
Romero
Beatriz
B
de Juan
Lucía
L
Mateos
Ana
A
Gómez-Mampaso
Enrique
E
Domínguez
Lucas
L
D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D018834:Chaperonin 60; D018833:Chaperonins / Q000235:genetics; D004251:DNA Transposable Elements; D016521:Electrophoresis, Gel, Pulsed-Field; D004865:Equipment and Supplies, Hospital / Q000382:microbiology*; D005618:Fresh Water / Q000382:microbiology*; D014644:Genetic Variation; D006761:Hospitals; D006801:Humans; D015269:Mycobacterium avium Complex / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D015270:Mycobacterium avium-intracellulare Infection / Q000175:diagnosis / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods; D013183:Sputum / Q000382:microbiology; D014556:Urine / Q000382:microbiology; D014881:Water Supply
D001426:Bacterial Proteins; D018834:Chaperonin 60; D004251:DNA Transposable Elements; C074119:heat-shock protein 65, Mycobacterium; D018833:Chaperonins