Detección y genotipificación de Pneumocystis jirovecii en muestras de pacientes mexicanos VIH positivos y negativos / Detection and genotyping of Pneumocystis jirovecii in samples from HIV positive and negative Mexican patients

Resumen Introducción: Pneumocystis jirovecii es un hongo atípico detectado particularmente en pacientes VIH-positivos o con trasplante. Objetivo: Detectar y genotipificar Pneumocystis jirovecii en muestras de pacientes de dos hospitales de la ciudad de México. Método: Fueron procesadas 89 muestras respiratorias, correspondientes a 53 pacientes (30 VIH positivos y 23 VIH negativos) con sintomatología respiratoria y 11 personas sanas incluidas como control negativo. El DNA fue extraído y amplificado por PCR anidada de la región del espaciador transcrito interno, obteniendo un fragmento en cada ronda (de 693 y 550 pb). Los genotipos y su relación filogenética fueron determinados por secuenciación del fragmento de 550 pb. Resultados: Cuarenta y ocho muestras de 30 pacientes VIH-positivos provenían de un solo hospital, de las cuales 11 (36.6 %) fueron positivas a Pneumocystis jirovecii. Ninguna fue positiva en pacientes VIH-negativos o personas sanas. Los haplotipos detectados con mayor frecuencia fueron Eg y Em. Conclusiones: La frecuencia de infección por Pneumocystis jirovecii fue alta en la población mexicana estudiada. El genotipo más frecuente fue diferente a los reportados en otros países. Es necesario encauzar este problema de salud hacia la detección temprana de esta infección.

Abstract Introduction: Pneumocystis jirovecii is an atypical fungus particularly detected in HIV-positive or transplant patients. Objective: To detect and genotype Pneumocystis jirovecii in patient samples from two hospitals in Mexico City. Method: Eighty-nine respiratory tract samples, corresponding to 53 patients (30 HIV-positive and 23 HIV-negative) with respiratory symptoms and to 11 healthy individuals included as negative control, were processed. DNA was extracted from the ITS region and amplified by nested polymerase chain reaction from the internal transcribed spacer, with one fragment being obtained at each round (693 and 550 bp). Genotypes and their phylogenetic relationship were determined by sequencing the 550 bp fragment. Results: Forty-eight samples from 30 HIV-positive patients were received from a single hospital, out of which 11 (36.6 %) were positive for Pneumocystis jirovecii. No sample was positive in HIV-negative patients or healthy subjects. The most frequently detected haplotypes were Eg and Em. Conclusions: The frequency of Pneumocystis jirovecii infection was high in the studied Mexican population. The most common genotype was different from those reported in other countries. It is necessary to address this health problem through early detection of this infection.

Population structure and diversity of the pathogenic fungus Aspergillus fumigatus isolated from different sources and geographic origins

Fifty-five clinical and environmental Aspergillus fumigatus isolates from Mexico, Argentina, France and Peru were analyzed to determine their genetic variability, reproductive system and level of differentiation using amplified fragment length polymorphism markers. The level of genetic variability was assessed by measuring the percentage of polymorphic loci, number of effective alleles, expected heterozygocity and by performing an association index test (I A). The degree of genetic differentiation and variation was determined using analysis of molecular variance at three levels. Using the paired genetic distances, a dendrogram was built to detect the genetic relationship among alleles. Finally, a network of haplotypes was constructed to determine the geographic relationship among them. The results indicate that the clinical isolates have greater genetic variability than the environmental isolates. The I A of the clinical and environmental isolates suggests a recombining population structure. The genetic differentiation among isolates and the dendrogram suggest that the groups of isolates are different. The network of haplotypes demonstrates that the majority of the isolates are grouped according to geographic origin.