Search

International audience; Understanding the mechanisms involved in pathogen adaptation to quantitative resistance in plants has a key role to play in establishing durable strategies for resistance deployment, especially in perennial crops. The erosion of quantitative resistance has been recently suspected in Cuba and the Dominican Republic for a major fungal pathogen of such a crop: Pseudocercospora fijiensis, causing black leaf streak disease on banana. This study set out to test whether such erosion has resulted from an adaptation of P. fijiensis populations, and to determine whether or not the adaptation is local. Almost 600 P. fijiensis isolates from Cuba and the Dominican Republic were sampled using a paired-population sampling design on resistant and susceptible banana varieties. A low genetic structure of the P. fijiensis populations was detected in each country using 16 microsatellite markers. Cross-inoculation experiments using isolates from susceptible and resistant cultivars were carried out, measuring a quantitative trait (the diseased leaf area) related to pathogen fitness on three varieties. A further analysis based on those data suggested the existence of a local pattern of adaptation to resistant cultivars in both of the study countries, due to the existence of specific (or genotype by genotype) host-pathogen interactions. However, neither cost nor benefit effects for adapted populations were found on the widely used "Cavendish" banana group. These results highlight the need to study specific host-pathogen interactions and pathogen adaptation on a wide range of quantitative resistance phenotypes in banana, in order to develop durable strategies for resistance deployment.

An extensive survey was carried out in the Dominican Republic in order to monitor the prevalence of the three most widespread BSV species: Banana streak OL virus (BSOLV), Banana streak GF virus (BGFV) and Banana streak IM virus (BSIMV), in Macho x Hembra (MxH) and FHIA-21 plantains and in Cavendish dessert banana throughout all banana-producing areas. This survey led to the first detection of BSVs in the Dominican Republic. BSGFV was the most prevalent of the three targeted BSV species in both FHIA-21 and MxH varieties. Prevalence of BSGFV and BSOLV were substantially higher in FHIA-21 than in MxH. Molecular analysis of the eBSV pattern of sampled FHIA-21 and MxH plants showed that both varieties harbor infectious alleles OL1 (eBSOLV) and GF7 (eBSGFV) and are devoid of eBSIMV. Very low prevalence was recorded for both BSOLV and BSGFV in Cavendish banana, which is devoid of infectious eBSVs. BSIMV was not detected at all. Our results point to a marginal role of insect-borne transmission in the epidemiology of BSVs in the Dominican Republic.

The Tomato chlorotic spot virus (TCSV) was first reported in the 1980s, having its occurrence limited to Brazil and Argentina. Due to an apparent mild severity in the past, molecular studies concerning TCSV were neglected. However, TCSV has disseminated over the USA and Caribbean countries. In Dominican Republic TCSV has been recently reported on important cultivated crops such as pepper and beans. In this work, we provide the first complete genome of a TCSV isolate from symptomatic plants in Dominican Republic, which was obtained by high-throughput sequencing. In addition, three dsRNA viruses from different virus families were identified coinfecting these plants Bell pepper endornavirus (BPEV), Southern tomato virus (STV) and Pepper cryptic virus 2 (PCV-2). Phylogenetic analysis showed that the Dominican Republic TCSV isolate has a close relationship with other TCSV isolates and a reassortant isolate between TCSV and Groundnut ringspot virus (GRSV), all found in USA. BPEV, STV and PCV-2 isolates from Dominican Republic were close related to corresponding American isolates. The possible biological implications of these virus-mixed infections are discussed.

BACKGROUND To identify the epidemiology and risk factors with influence in the outcome and mortality of a series of bacteriemic patients. MATERIAL AND METHODS A prospective study of bloodstream infections with clinical significance detected in a secondary hospital of 650 beds over period from May 1998 to May 1999. The true bacteriemia was defined in basis to the criteria both the physician and microbiologist. A total of 16 variables were defined and categorized such as clinical-epidemiologic, intrinsic risk factor, extrinsic risk factor, outcome and survival. We used SPSS statistical package: For cuantitative variables we carried out with the mean with confidence interval of 95%, for cualitative variables: number and %. Univariate analysis of the results was carried out with the X2 test and t Student, the survival was expressed with Kaplan Meyer graphics and the logistic regression model. RESULTS A total of 320 positive blood cultures were studied but only 272 blood cultures were considered true bacteriemia in 259 patients. The calculated incidence of significant episodes of bacteriemia per 1000 admissions/year was 13. The overall mortality was 22% whereas death attributable to bacteriemia was 16%. The mean age was 66.9 years (IC 95% 65-69), 59% episodes occurred in men. The 78% episodes occurred in patients hospitalized in medical services. 52% episodes were of nosocomial infection and 48% of community acquired infection. According to the severity of the underlying disease, 15% had fatal diseases and 35% episodes occurred in patients without underlying disease. According to the univariant analysis, the variables which where significantly associated with greater risk death were: etiology (fungus), septic shock, the inadequate antibiotic therapy, presence of extrinsic factors (central intravenous catheter, performance of invasive procedures, previous antimicrobial therapy) and the hospital stay of less than 10 days. According to the multivariable analysis showed that the factors remaining independent predictors of mortality were: septic shock (p < 0.0001, OR: 8), inadequate antimicrobial therapy (p < 0.005, OR: 6.7), existence of two or more extrinsic risk factors (p < 0.04). CONCLUSIONS The presence of septic shock was the most important variable which influenced in the mortality in our serie, together with inappropriate antimicrobian therapy and the association of various extrinsic risk factors. These variables could be modified partly, for this reason the aggressive hemodynamic control and the early and appropriate antibiotic therapy would be the support of the successful bacteriemia management.