Se evaluó la capacidad invasiva de aislamientos clínicos y de colección de varias especies de micobacterias no pigmentadas de crecimiento rápido mediante el análisis de las microcolonias en cultivo ...de fibroblastos diploids humanos, y se comparó la misma con el fenotipo de colonias en medio de Middlebrook 7H11 y con el significado clínico de los aislamientos.
Se analizaron 29 cepas de:
Mycobacterium chelonae (8),
M. fortuitum (6),
M. peregrinum (5),
M. abscessus (5),
M. mucogenicum (4) y
M. septicum (1), tanto clínicamente significativas como de colección. Se evaluó el fenotipo liso o rugoso de las colonias en Middlebrook 7H11. Se evaluó la capacidad de invasion intracelular mediante el ensayo de microcolonias en fibroblastos descrito por Shepard. Las características cuantitativas se compararon con el test de la t de Student y las características cualitativas con el test exacto de Fisher.
No se encontraron diferencias significativas entre colonias de fenotipos distintos o cepas con diferentes significados clínicos, excepto en dos aislamientos de
M. chelonae de bacteriemia relacionados con catéteres, que presentaron microcolonias alargadas en el cultivo celular. Las cepas de
M. fortuitum y
M. peregrinum presentaron microcolonias más grandes y de apariencia desflecada, mientras que las de
M. chelonae,
M. abscessus o
M. mucogenicum, presentaron unas colonias más pequeñas y de apariencia redondeada.
La capacidad invasiva está presente solamente en unas pocas cepas de micobacterias, y esta característica no aparece en la mayoría de las cepas aisladas de infecciones en humanos y en ninguna de las que no fueron clínicamente significativas, por lo que no sería una característica esencial para que los diversos aislamientos sean causa de enfermedad en humanos.
The invasive capacity of rapidly-growing nonpigmented mycobacteria strains was evaluated by means of a fibroblast microcolony assay and related to the colony phenotype on Middlebrook 7H11 and to the clinical significance of the isolates.
Twenty-nine strains
Mycobacterium chelonae (8),
M. fortuitum (6),
M. peregrinum (5),
M. abscessus (5),
M. mucogenicum (4) and
M. septicum (1), proceeding from a bacterial collection and clinical isolates, were evaluated. The smooth or rough phenotype of the colonies was assessed in Middlebrook 7H11 medium. Intracellular invasiveness was determined by the fibroblast-microcolony assay described by Shepard. Quantitative culture characteristics were compared with tudent's t-test, and qualitative characteristics with Fisher's exact test.
No significant differences were found between colonies with different phenotypes or strains having a different clinical significance, except for two strains of
Mycobacterium chelonae isolated from cases of catheter-related bacteremia, which showed elongated microcolonies.
M. fortuitum and
M. peregrinum strains showed larger microcolonies than
M. chelonae,
M. abscessus and
M. mucogenicum, and displayed a fluffy appearance, while the latter two strains showed rounded olonies.
Very few strains of mycobacteria had invasive capacity and the majority of strains isolated from human infections do not show this characteristic; hence this trait is not essential for mycobacteria to cause infection in humans.
Fungal peritonitis is an uncommon, serious complication of peritoneal dialysis, usually caused by Candida sp . Asymptomatic fungal colonization of the peritoneal catheter is less frequent. ...Penicillium sp have only rarely been reported as a cause of peritoneal complications in peritoneal dialysis. We report a case of fever and peritoneal catheter malfunction associated with catheter colonization by Penicillium sp , in the absence of signs or symptoms of acute peritonitis. Cultures of the dialysate grew Penicillium sp, and histological examination showed penetration of the catheter by hyphae. The peritoneal catheter was removed, and the patient was maintained on hemodialysis and oral itraconazole for 6 weeks before successfully returning to continuous cycling peritoneal dialysis (CCPD). One case of Penicillium catheter colonization and seven of Penicillium peritonitis in peritoneal dialysis patients have been previously published in the English literature. Detailed data were provided in five reports. Delayed diagnosis was frequent (mean ± SD 31 ± 24 days after the onset of symptoms). Peritonitis cases were treated with catheter removal and antifungal medications, and the outcome was always satisfactory. We conclude that Penicillium should be considered a pathogenic fungus, not a contaminant, when isolated from peritoneal dialysis specimens, and should be treated accordingly. However, Penicillium may colonize the peritoneal catheter in the absence of peritonitis, and the prognosis of Penicillium peritonitis is good despite a frequent delay in diagnosis.
Molecular diagnosis of parasitic and fungal infections Borrás Salvador, Rafael; Cuenca-Estrella, Manuel; Domínguez Márquez, María Victoria ...
Enfermedades infecciosas y microbiología clínica
26 Suppl 9
Journal Article
Recenzirano
Conventional microbiological diagnosis of fungal infections and parasitic diseases has been characterized by low diagnostic sensitivity, laboriousness, and the need for expert microscopists. ...Consequently, diagnostic methods based on the detection of nucleic acids are a magnificent alternative to overcome these problems, but have not yet provided a satisfactory response in all situations. The molecular methods used are varied and most are based on techniques of nucleic acid amplification. These techniques have proved useful for mycological and parasitological diagnosis, for epidemiological and taxonomic studies, and for monitoring the response to different treatments and detection of resistance. The introduction of these techniques in developing countries may be hampered by their higher cost but molecular diagnostic methods are already beginning to spread in clinical microbiology laboratories and are competing successfully with traditional methods. The present article reviews the current status of molecular methods in the diagnosis of fungal and parasitic infections.
El diagnóstico microbiológico convencional de las infecciones fúngicas y parasitarias se ha caracterizado por su escasa sensibilidad diagnóstica, su laboriosidad y la necesidad de microscopistas ...experimentados. Frente a ellos, los métodos diagnósticos basados en la detección de ácidos nucleicos son una alternativa magnífica para superar estos problemas, aunque todavía no han dado respuesta satisfactoria a todas las situaciones. Los métodos moleculares utilizados son variados, la mayoría basados en técnicas de amplificación de ácidos nucleicos, y han demostrado ser útiles para los diagnósticos micológico y parasitológico, los estudios epidemiológicos y taxonómicos, y para el seguimiento de la respuesta a los diferentes tratamientos y la detección de resistencias. Es posible que su implantación presente dificultades en los países en vías de desarrollo, debido a su mayor coste; pero los métodos de diagnóstico molecular ya comienzan a extenderse en los laboratorios de microbiología clínica y rivalizan, con éxito, con los métodos clásicos. En este trabajo, nos proponemos revisar la situación actual de los métodos moleculares en el diagnóstico de las infecciones fúngicas y parasitarias.
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