Maria del Carmen Candia-Plata

Clinical profile and predictors of fatal Rocky Mountain spotted fever in children from Sonora, Mexico.

Background: Rocky Mountain spotted fever (RMSF) is an increasingly important cause of preventable mortality in children in Sonora, Mexico. Although early treatment with tetracycline has shown to prevent fatal outcome, the disease remains a life-threatening condition, particularly for children. This study describes the clinical factors associated with pediatric mortality due to RMSF in Sonora, in order to guide healthcare practices. Methods: This is a retrospective analysis of 104 children consecutively hospitalized at the major pediatric hospital of Sonora, diagnosed with RMSF between January 2004 and December 2013. Descriptive statistics and multiple logistic regression were used to identify risk factors for fatal outcome. Results: The case fatality ratio in this cohort was 20.2%. Children were hospitalized after a median of 6 days from onset of symptoms including fever (100%), rash involving palms and soles (88.5%) and headache (79.8%); 90.4% of fatal cases had low platelet counts (<50,000/&mgr;L) and 33.3% showed serum creatinine concentrations above the normal value. Acute kidney injury increased mortality, odds ratio (ORadj) = 4.84, 95% confidence interval (CI): 1.2–16.2, as well as delay in treatment (≥ 5th day from onset) with doxycycline, ORadj = 2.62, 95% CI: 1.24–5.52 and hemorrhage, ORadj = 6.11, 95% CI: 1.89–19.69. Conclusions: RMSF is a public health problem in Sonora. Clinically, fatal cases differ from non-fatal cases in renal function and hemorrhagic manifestations, although these findings may occur too late for a timely intervention. First-line providers must be educated to harbor a timely suspicion of RMSF, and should provide empiric treatment with doxycycline when febrile patients first present for care.

Proposal of a Screening MIRU-VNTR Panel for the Preliminary Genotyping of Mycobacterium bovis in Mexico

Mycobacterium bovis is the major causative agent of bovine tuberculosis, one of the most relevant zoonoses in the world, and affects a wide range of wild and domesticated animals. Development of screening panels in mycobacterial genotyping, according to specific geographical regions, is strongly needed. The aim of this study is to select a panel, constituted by highly polymorphic MIRU-VNTR loci, to discriminate clinical isolates of M. bovis in Mexico. In this study, 65 isolates of M. bovis obtained from clinical bovine samples proceeding from different geographic regions of Mexico were identified by phenotypic and genotypic tests and subsequently genotyped by a 24-locus MIRU-VNTR panel. The most polymorphic loci were selected to build a panel with a high discriminatory power similar to the 24-locus panel results. A panel of seven elements (QUB 11a, MIRU 26, ETR-A, QUB 26, MIRU 16, MIRU 27, and MIRU 39) with the highest allelic diversity showed an appropriate differentiation. The selected MIRU-VNTR elements, according to the regional allelic variability, may be used in the preliminary genotyping of Mycobacterium bovis isolates in Mexico.

Mutaciones asociadas con resistencia a rifampicina o isoniazida en aislamientos clínicos de M. tuberculosis de Sonora, México

OBJETIVO: Realizar el analisis de regiones especificas de genes asociados con resistencia a isoniazida o rifampicina. MATERIAL Y METODOS: Se estudiaron 22 cepas de M. tuberculosis, aisladas en Sonora, Mexico. Se utilizaron iniciadores para regiones especificas de los genes rpoB, katG e inhA y la region ahpC-oxyR. Los productos de PCR se secuenciaron y analizaron. RESULTADOS: Se identificaron mutaciones en la region promotora del gen inhA, region ahpC-oxyR, codon 315 del gen katG y codones 451 o 456 del gen rpoB. CONCLUSIONES: La identificacion de mutaciones no descritas previamente obliga a continuar el analisis genotipico de cepas aisladas en Sonora.

Medical knowledge related to Rocky Mountain spotted fever in Sonora, Mexico

Background Rocky Mountain spotted fever (RMSF) is a tick-borne disease with a high case-fatality rate unless diagnosed promptly and treated timely with doxycycline. Physician knowledge about presentation and treatment can improve outcomes of RMSF in endemic regions, such as Sonora in northern Mexico, where RMSF has caused 1348 non-fatal cases and 247 deaths from 2003 to 2016. Methods A cross-sectional study was conducted with 343 physicians working in medical facilities in Sonora, Mexico. A 25-item questionnaire explored physician knowledge of clinical, epidemiological and preventive aspects of RMSF. Results Only 62% of physicians agreed that doxycycline should be used as the first choice treatment for children under 8 years with suspected RMSF. Additionally, 40% of primary care physicians correctly identified the time to initiate doxycycline, and 32% correctly identified the case-fatality rate of untreated RMSF in all patients. Conclusions Inadequate medical knowledge may adversely affect how patients infected with Rickettsia rickettsii are diagnosed and treated. Educational programs that improve the risk perception and medical knowledge about RMSF should be targeted at physicians most likely to have initial contact with diseased patients.

Rocky Mountain Spotted Fever and Pregnancy: Four Cases from Sonora, Mexico

We present a series of four pregnant women with Rocky Mountain spotted fever (RMSF) that occurred in Sonora, Mexico, during 2015-2016. Confirmatory diagnoses were made by polymerase chain reaction or serological reactivity to antigens of Rickettsia rickettsii by using an indirect immunofluorescence antibody assay. Each patient presented with fever and petechial rash and was treated successfully with doxycycline. Each of the women and one full-term infant delivered at 36 weeks gestation survived the infection. Three of the patients in their first trimester of pregnancy suffered spontaneous abortions. RMSF should be suspected in any pregnant woman presenting with fever, malaise and rash in regions where R. rickettsii is endemic.

USO DE LA LECTINA DE OLNEYA TESOTA (PF2) PARA LA PURIFICACIÓN Y DETECCIÓN HISTOQUÍMICA DE UNA PROTEÍNA DE CHOQUE TÉRMICO (GP14) DE BAZO/ USE OF THE Olneya tesota LECTIN (PF2) FOR PURIFICATION AND HISTOCHEMICAL DETECTION OF A SPLEEN HEAT SHOCK PROTEIN

PF2 es una lectina de las semillas de Olneya tesota (Palo ferro) con afnidad alta hacia carbohidratos complejos triantenarios tetrasialilados. El objetivo de este estudio fue localizar glicoconjugados que interactuen con PF2 en secciones de tejido de bazo y purifcar glicoproteinas usando cromatografia de afnidad con PF2. Se incubaron secciones fnas de tejido de bazo con PF2 biotinilada y se observaron interacciones con linfocitos en los nodulos y estructuras internas de tipo reticular en la pulpa blanca. Se prepararon extractos de bazo para purifcar la glicoproteina detectada, usando dos etapas cromatografcas, intercambio ionico (CMcelulosa) y afnidad (PF2-agarosa). Por electroforesis nativa y con SDS se mostro una glicoproteina monomerica de 14 kDa (GP14). Una vez digerida con una proteasa, se identifcaron seis secuencias peptidicas en la GP14. Cada peptido mostro 100% de homologia a secuencias internas de diferentes proteinas de choque termico de la familia de 70 kDa (HSP70). Esta similitud con las HSP fue confrmada por electrotransferencia e inmunodeteccion usando anticuerpos especifcos para HSP70. En conclusion, la lectina PF2 tiene especifcidad hacia un glicoconjugado denominado GP14 que pudiera ser una glicoproteina de estres del bazo humano, identifcada por primera vez

Codificación geométrica y análisis de conglomerados para evaluar el control metabólico de pacientes con diabetes mellitus tipo 2

OBJETIVO: Determinar la frecuencia de las combinaciones de los parametros de control metabolico por arriba de lo normal, usando la codificacion geometrica y el analisis jerarquico de conglomerados, en pacientes con diabetes mellitus tipo 2 (DM2). METODOS: Se desarrollo en Mexico un estudio transversal descriptivo para evaluar a un grupo de 1 051 pacientes con DM2, cuyos criterios de inclusion eran tener uno o mas de los siguientes valores: glucosa en ayunas > 130 mg/dL, colesterol total > 240 mg/dL, trigliceridos totales > 200 mg/dL, indice de masa corporal > 27 kg/m², y presion arterial sistolica mayor de 130 mmHg o presion arterial diastolica mayor de 85 mmHg. Por medio de codificaciones geometricas se obtuvieron las frecuencias de todas las combinaciones. Para definir similitudes entre las combinaciones se utilizo el metodo de analisis de conglomerados. RESULTADOS: Utilizando el instrumento propuesto, se observo que la combinacion en pares con mayor numero de sujetos estuvo representada por hiperglucemia-hipertrigliceridemia (7,3%) e hiperglucemia-hipercolesterolemia (3,6%). Las policombinaciones de mayor frecuencia fueron hiperglucemia-hipercolesterolemia-hipertrigliceridemia (13,2%) e hiperglucemia- hipertrigliceridemia-hipercolesterolemia-hipertension (10,5%). CONCLUSIONES: La codificacion geometrica y el analisis por conglomerados podrian llegar a ser un instrumento idoneo para evaluar el control metabolico de los pacientes con DM2, asi como para identificar parametros que contribuyan a mejorar su monitoreo y su tratamiento.