Genetic Diversity among Strains of Mycobacterium avium Causing Monoclonal and Polyclonal Bacteremia in Patients with AIDS

Abstract

To define the genetic diversity among Mycobacterium avium isolates from human immunodeficiency virus-infected patients, specimens were cultured prospectively, and isolates obtained from 14 patients (4 with positive blood, stool, and sputum; 6 with positive blood and stool; 3 with positive blood only; and 1 with positive stool only) were studied. Both serotyping and ribotyping had limited ability to discriminate among isolates from different patients, whereas the distinctive restriction fragment profiles resolved by pulsed-field gel electrophoresis indicated that each patient was infected by a unique strain. Of the 13 bacteremic patients, 2 were bacteremic concurrently with 2 distinct strains. The fact that M. avium isolates from AIDS patients exhibit considerable genetic diversity supports the hypothesis that the infection is acquired from various environmental sources. Further, individual patients are not infrequently bacteremic with> 1 strain simultaneously, which may need to be considered in protocols for the diagnosis and management of M. avium disease.

Genetic characterization ofMycobacterium aviumisolates recovered from humans and animals in Australia

“…Pulsed field gel electrophoresis (PFGE) also has been shown to be useful for identification of specific strains [27][28][29][30][31].…”

Evaluation of a High-Throughput Repetitive-Sequence-Based PCR System for DNA Fingerprinting of Mycobacterium tuberculosis and Mycobacterium avium Complex Strains

“…Genotypic analysis of atypical mycobacteria, most notably the M. avium complex (MAC), has been similarly useful for investigating routes of acquisition from environmental sources, confirming contamination of laboratory cultures, and studying clonal expansion (2,11,29).…”

“…A consensus protocol for IS1245-RFLP (24) has good resolving power when the element is present in moderate copy number (5 to 30 copies), however like IS6110-RFLP it requires large cell mass and is labor intensive. Pulsed-field gel electrophoresis (2,29) also requires a large cell mass, and few laboratories have the required equipment. Not surprisingly given the limited molecular epidemiological tools available for MAC and other environmental mycobacteria, our understanding of the routes of acquisition of these opportunistic pathogens remains limited.…”

Mycobacterium avium restriction fragment lenght polymorphism-IS IS1245 and the simple double repetitive element polymerase chain reaction typing method to screen genetic diversity in Brazilian strains

“…In summary, this study shows that the rapid, easy, and inexpensive PCR typing based on two M. avium-insertion sequences is useful for epidemiological studies such as detection of polyclonal infection, an event that may have treatment implications (Arbeit et al 1993, Saad et al 2000, Panunto et al 2003). However we suggest to strict its use in small sampling from select set because of the limitation on analysis of patterns with difference in one band.…”

“…In the last decade available molecular methods have been useful for strains differentiation and for the understanding of epidemiological transmission of this environmental pathogen. M. avium has been typed successfully by IS1245-restriction fragment length polymorphism (RFLP) and pulsed field gel electrophoresis (PFGE) (Arbeit & Slutsky 1993, Devallois & Rastogi 1997, Ritacco et al 1998, Saad et al 1999, Legrand et al 2000. However these methods are time consuming and expensive, besides they need a lot of extracted DNA.…”