[Evaluation of four methods for detecting methicillin-resistant Staphylococcus aureus isolates from clinical specimens at a regional hospital in Mexico]. / Evaluación de cuatro métodos para la detección de Staphylococcus aureus meticilino-resistente de muestras clínicas en un hospital regional.

OBJECTIVE: To estimate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in clinical isolates and to compare different methods for detection of MRSA in a lab with limited available personnel and resources. MATERIAL AND METHODS: 140 Staphylococcus aureus strains isolated from patients in several departments were assayed for ß-lactamase production, MIC-Vitek 2 oxacillin, ChromID MRSA, disk diffusion in agar for cefoxitin 30 µg and PBP2a detection. The results of conventional tests were compared with the "gold standard" PCR test for mecA gene. Cohen´s kappa index was also calculated in order to evaluate the intra assay agreement between the used methods. RESULTS: The found prevalence was 90.7%. Sensitivity and specificity were: disk diffusion for cefoxitin 97 and 92% respectively, MIC Vitek 2-XL 97 and 69%, ChromoID MRSA 97 and 85%, and PBP2a detection 98 and 100%. CONCLUSIONS: All methods are very good for detecting MRSA, choosing a method to use will depend on each laboratory infrastructure.

[Analysis of Bcr-abl type transcript and its relationship with platelet count in Mexican patients with chronic myeloid leukemia]. / Análisis del tipo de transcrito bcr-abl y su relación con la cuenta plaquetaria en pacientes mexicanos con leucemia mieloide crónica.

PROBLEM: It has been suggested that type of chimeric mRNA is associated with differences in the clinical and hematologic characteristics of chronic myeloid leukemia (CML). However, prognostic value of type of chimeric mRNA bcr-xabl (b3a2 or b2a2) is still controversial. METHODS: We analyzed 97 cases of Philadelphia-positive CML to determine mRNA type by reverse-polymerase chain reaction (RT-PCR) and its relationship with clinical features. RESULTS: We detected b3a2 bcr-abl transcripts in 27 (28%) cases, b2a2 in 57 (59%) cases, and 13 (13%) with both mRNA transcripts b3a2/b2a2. These frequencies were the total reverse of other reports. Age, sex, hemoglobin, and white-cell counts showed no significant difference for those with either b3a2 or b2a2 bcr-abl transcripts. However, platelet counts of b3a2 patients were significantly higher than those of b2a2 patients (743.3 vs 477.3 x 109/L; p = 0.01). In addition, in the subgroup of patients whose white-cell count at diagnosis was < 100 x 10(9)/L, those with b3a2 transcript had a significantly higher platelet count (679.1 vs. 352.2 x 10(9)/L; p = 0.001). CONCLUSIONS: We observed reversed frequency of bcr-abl transcripts in this population, but agreement with other Latin-American reports. In addition, our data suggested that there is different CML biological behavior in our population and that there is a subpopulation of CML patients in whom b3a2 is associated witH higher thrombopoietic activity.

Evaluación de cuatro métodos para la detección de Staphylococcus aureus meticilino-resistente de muestras clínicas en un hospital regional / Evaluation of four methods for detecting methicillin-resistant Staphylococcus aureus isolates from clinical specimens at a regional hospital in Mexico

OBJETIVO: Investigar la prevalencia de Staphylococcus aureus meticilino-resistente (MRSA) en aislados clínicos y determinar la concordancia entre los métodos de detección de MRSA en un laboratorio con recursos y personal limitado. MATERIAL Y MÉTODOS: Se analizaron 140 cepas de Staphylococcus aureus aisladas de muestras clínicas de diferentes departamentos mediante pruebas convencionales: producción de β-lactamasa, sensibilidad a oxacilina con MIC-Vitek 2-XL, ChromID MRSA, difusión en agar para discos de 30 μg de cefoxitina, detección de PBP2a y PCR para el gen mecA. Se determinó el índice kappa de Cohen, para evaluar la concordancia entre los diferentes métodos utilizados. RESULTADOS: La prevalencia encontrada fue de 90.7 por ciento. La sensibilidad y especificidad para los diferentes métodos de detección fue: difusión en disco para cefoxitina 97 y 92 por ciento respectivamente, MIC Vitek 2-XL 97 y 69 por ciento, ChromoID MRSA 97 y 85 por ciento y detección de PBP2a 98 y 100 por ciento. CONCLUSIONES: Todos los métodos son muy buenos para la detección de MRSA; la elección en el uso de cada método dependerá de la infraestructura de cada laboratorio.

OBJETIVE: To estimate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in clinical isolates and to compare different methods for detection of MRSA in a lab with limited available personnel and resources. MATERIAL AND METHODS: 140 Staphylococcus aureus strains isolated from patients in several departments were assayed for β-lactamase production, MIC-Vitek 2 oxacillin, ChromID MRSA, disk diffusion in agar for cefoxitin 30 μg and PBP2a detection. The results of conventional tests were compared with the "gold standard" PCR test for mecA gene. Cohen´s kappa index was also calculated in order to evaluate the intra assay agreement between the used methods. RESULTS: The found prevalence was 90.7 percent. Sensitivity and specificity were: disk diffusion for cefoxitin 97 and 92 percent respectively, MIC Vitek 2-XL 97 and 69 percent, ChromoID MRSA 97 and 85 percent, and PBP2a detection 98 and 100 percent. CONCLUSIONS: All methods are very good for detecting MRSA, choosing a method to use will depend on each laboratory infrastructure.