Species Identification of Mycobacterium avium Complex Isolates by a Variety of Molecular Techniques (original) (raw)
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Journal of Medical Microbiology, 2005
This report describes an unusual strain of Mycobacterium avium complex isolated from the sputum of an immunocompromised AIDS patient, which did not react with the MAC probe of the BDProbe Tec system, but was identified as Mycobacterium intracellulare by 16S rRNA gene sequencing. Its PCR restriction-enzyme analysis pattern was compatible with an allelic variant of M. avium. It was scotochromogenic, slow-growing and phenotypically identified as Mycobacterium scrofulaceum. Its clinical significance is not certain.
Genetic and serovar typing of clinical isolates of the Mycobacterium avium-intracellulare complex
Tubercle and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease, 1996
One hundred and thirty-four Mycobacterium avium-intracellulare complex (MAC) isolates were obtained from 121 patients in the UK. To compare serotyping and genetic analysis for species identification of MAC isolates from patients with and without the acquired immunodeficiency syndrome (AIDS). Clinical MAC isolates were cultured and analyzed by serotyping, the commercially available Accuprobe kit, hybridization with genes coding for the 19 kDa and 38 kDa antigens of M. tuberculosis and fingerprinting with the pMB22 probe derived from M. paratuberculosis. Species classification on the basis of genetic analysis was similar to serovar typing, with only exceptional discrepancies. Serovar prevalence was different in the two groups of patients, and different from those reported in other countries. MAC isolates from AIDS patients were exclusively M. avium, whereas patients without AIDS had MAC infections with M. avium and M. intracellulare in about equal proportion. M. intracellulare clinica...
Current Microbiology, 1996
A genetic fingerprinting analysis of Caribbean isolates of M. avium complex (MAC) from AIDS patients by a Southern blotting technique after Pstl digestion with nonradioactive DNA probes coding for single-copy sequences DT1 and DT6 was performed. In parallel, a selective amplification of a 187-bp fragment within the DT6 sequence with AV6/AV7 primers for Mycobacterium avium and of a 666-bp fragment within the DT1 sequence of M. intracellulare with the IN38/IN41 primers was also performed, and the molecular speciation with these two methods was compared with results obtained with DNA probes of the Accuprobe system. 66 strains investigated comprised 31 international reference isolates of MAC belonging to serovars 1-28 and 42-44, and 35 clinical isolates including 24 strains from Caribbean AIDS patients. 91.43% of the clinical isolates tested gave concordant data with the DT1/DT6 Southern hybridization and PCR as compared with 74.28% for PCR and Accuprobe, and 71.43% for Accuprobe and Southern hybridization. Our results corroborated previous findings showing that the DT1 probe was specific for M. intracellulare, whereas the DT6 probe was specific for M. avium (reference serovars 2 and 3 probed positive both with DT1 and DT6 probes). Contrary to DT1 probe, which did not reveal sufficient polymorphism to discriminate between MAC isolates, DT6 probe showed an interesting polymorphism giving four distinct clusters. Three clusters corresponded to profiles previously reported for reference and/or clinical isolates; however, a fourth cluster was discovered in five Caribbean isolates from four AIDS patients that did not correspond to previously published genetic patterns. When probed with the insertion sequence IS1245, this cluster retained its homogeneity.
Tropical Medicine and International Health, 1997
Thirteen isolates from African AIDS patients and from the environment in Zaire were identified as members of the Mycobacterium avium complex by phenotypic tests. RFLP analysis showed that the isolates belong to a genetically homogeneous cluster. The 16S rRNA sequence analysis suggests a close relationship with the P-49 strain (ATCC 35847), a reference strain for the serotype 7 of M. avium complex. This work shows the close relationship between certain M. avium complex strains responsible for disseminated infection in AIDS patients and M. avium complex strains isolated from the environment in Zaire. Further, our findings confirm that atypical mycobacteria may disseminate in AIDS patients in Africa and suggest that infection in these patients probably originates in their environment.
Journal of Clinical Microbiology, 2008
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.
Genotype analysis of human Mycobacterium avium isolates from India
The Indian journal of medical research, 2006
Mycobacterium avium has emerged as a major opportunistic pathogen, infecting nearly 50 per cent of HIV/AIDS patients in the western world. There is no report from India regarding the typing profile of M. avium, a potential pathogen, the present study was undertaken to assess the genotypic diversity of Indian M. avium isolates of human origin. A total of 65 biochemically identified M. avium isolates from sputum samples of patients with chronic pulmonary illness were subjected to IS1245 based restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR) typing. IS1245 insertion sequence based RFLP demonstrated polymorphism in 84.6 per cent isolates, while 15.4 per cent isolates did not hybridize on Southern blot and therefore were RFLP negative. Among the 55 RFLP positive isolates, 8 showed 1-3 bands, 19 had bands ranging between 4-9, and 28 isolates had >10 bands each. Although the isolates could be clubbed on the basis of number of bands, the banding profile...