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Genetic diversity of Mycobacterium avium isolates among Slovenian patients

Abstract number: r2225

Pate  M., Zolnir-Dovc  M., Ocepek  M., Krt  B.

Objectives: 

The objectives of this study were to characterize the genetic diversity of human Mycobacterium avium isolates collected at the National Reference Laboratory for Mycobacteria (UC Golnik) between 2002 and 2004.

Methods: 

A total of 60 isolates from 27 patients were collected over a three-year period and identified with the classical biochemical tests and a commercially available AccuProbe®Mycobacterium avium Culture Identification Test (Gen-Probe Inc., San Diego, CA, USA). All the isolates were tested with duplex PCR discriminating between M. avium and M. intracellulare in order to discover any double infections. IS1245-IS1311 spacer PCR typing and IS1245 RFLP were performed to study the genetic diversity of the isolates.

Results: 

Duplex PCR revealed double infection (M. avium/M. intracellulare) in four isolates from one patient. IS1245-IS1311 spacer PCR typing showed heterogenic patterns usually comprising up to 6 bands. Albeit simple and rapid, the method lacked sufficient discriminatory power. Fifty-five out of 60 isolates were successfully IS1245 RFLP typed. The patterns showed a high degree of heterogeneity, with the number of the bands mostly ranging from 20 to 30. When using the shorter of the two different IS1245 probes, the patterns generally consisted of fewer bands and were easier to read. In 12 patients, sequential isolates (n = 45) collected in different time periods, were compared. Infections were clinically important and treated in 7 patients. Identical RFLP patterns were seen in the majority of the sequential isolates from certain patients.

Conclusions: 

In comparison with IS6110 RFLP patterns of M. tuberculosis, IS1245 RFLP patterns of human M. avium strains are quite diverse and substantially harder to interpret, partly due to numerous bands and partly due to frequent occurrence of faint bands. The latter can be eliminated with careful primer design for the IS1245 probe to avoid cross-hybridization with IS1311. Identical patterns of the sequential isolates collected from certain patients over a longer period of time indicate clinical importance of the infection. M. avium infection will remain a challenging clinical problem due to the ubiquitous nature of the bacillus, increasing number of immunocompromized patients and demanding treatment trials.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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