Comparison of Mycobacterium avium isolates from Greek AIDS and human immunodeficiency virus-negative patients by pulsed-field gel electrophoresis.

OBJECTIVE: To compare the chromosomal types of Mycobacterium avium strains infecting HIV-negative and AIDS patients in Greece. METHODS: In total, 41 Mycobacterium avium isolates, 23 from AIDS and 18 from HIV-negative patients, were compared by pulsed-field gel electrophoresis of genomic DNA after XbaI digestion. The majority (87%) of AIDS isolates were from disseminated infection, while the majority (61%) of HIV-negative isolates were from children with cervical lymphadenitis. RESULTS: Pulsed-field gel electrophoresis classified strains whose electrophoretic patterns were at least 85% similar into three clusters, A (four isolates), B (12 isolates), and C (15), while 10 isolates remained outside of these clusters. There was no statistically significant correlation of any PFGE cluster with a specific patient group. Within each patient group, no significant correlation of PFGE type with time, place of residence or, in the case of AIDS patients, hospital attended was observed. CONCLUSIONS: Genotypic similarities between isolates responsible for disseminated infection in AIDS patients and lymphadenitis in HIV-negative children suggest that related strains, possibly from an environmental source, cause both types of infections.