RESUMEN
Fine-scale genotyping methods are necessary in order to identify possible sources of human exposure to opportunistic pathogens belonging to the Mycobacterium avium complex (MAC). In this study, amplified fragment length polymorphism (AFLP) analysis was evaluated for fingerprinting 159 patient and environmental MAC isolates from southern California. AFLP analysis accurately identified strains belonging to M. avium and Mycobacterium intracellulare and differentiated between strains within each species. The method was also able to differentiate strains that were presumed to be genetically identical in two previous studies using large RFLP analysis with PFGE, or PCR-amplification of DNA segments located between insertion sequences IS1245 and IS1311. For M. avium, drinking-water isolates clustered more closely with each other than with patient or food isolates. Patient isolates were more genetically diverse. None of the environmental isolates shared identical AFLP patterns with patient isolates for either species. There were, however, environmental isolates that shared identical patterns, and patient isolates that shared identical patterns. A subset of the isolates, which are referred to as MX isolates due to their ambiguous identification with the Gen-Probe system, produced AFLP patterns similar to those obtained from M. intracellulare isolates. Sequence analysis of 16S rDNA obtained from the MX isolates suggests that they are strains of M. intracellulare that were not correctly identified by the M. intracellulare AccuProbe from Gen-Probe.
Asunto(s)
Técnicas de Tipificación Bacteriana/métodos , Dermatoglifia del ADN/métodos , Complejo Mycobacterium avium/clasificación , Complejo Mycobacterium avium/genética , Infección por Mycobacterium avium-intracellulare/microbiología , Polimorfismo Genético , California/epidemiología , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Microbiología de Alimentos , Genotipo , Humanos , Datos de Secuencia Molecular , Mycobacterium avium/clasificación , Mycobacterium avium/genética , Mycobacterium avium/aislamiento & purificación , Complejo Mycobacterium avium/aislamiento & purificación , Infección por Mycobacterium avium-intracellulare/epidemiología , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Homología de Secuencia , Microbiología del AguaRESUMEN
The objective of this study was to examine bottled water for the presence of nontuberculous mycobacteria as a potential source of infection in AIDS patients. Twenty brands of bottled water commonly used in the Los Angeles area were tested for the presence of nontuberculous mycobacteria. The three brands most commonly used in the Los Angeles area were tested most frequently. Sixty-nine samples were filtered and the filters were treated using cetylpyridinium chloride, sodium hydroxide, or oxalic acid (or a combination of these) as decontaminants to remove background flora. An aliquot of each sample was untreated. The filters were placed on selective Middlebrook 7H10 agar plates containing 500 µg of cycloheximide per ml. Plates were examined at 3 and 8 weeks. No acid-fast organisms were found. Although no nontuberculous mycobacteria were observed in any samples tested, before recommending the use of bottled water as an alternative to tap water by high-risk patients, the possible presence of other contaminants must be considered.