Similarity-Based Predictive Models: Sensitivity Analysis and a Biological Application with Multi-Attributes.

Predictive models based on empirical similarity are instrumental in biology and data science, where the premise is to measure the likeness of one observation with others in the same dataset. Biological datasets often encompass data that can be categorized. When using empirical similarity-based predictive models, two strategies for handling categorical covariates exist. The first strategy retains categorical covariates in their original form, applying distance measures and allocating weights to each covariate. In contrast, the second strategy creates binary variables, representing each variable level independently, and computes similarity measures solely through the Euclidean distance. This study performs a sensitivity analysis of these two strategies using computational simulations, and applies the results to a biological context. We use a linear regression model as a reference point, and consider two methods for estimating the model parameters, alongside exponential and fractional inverse similarity functions. The sensitivity is evaluated by determining the coefficient of variation of the parameter estimators across the three models as a measure of relative variability. Our results suggest that the first strategy excels over the second one in effectively dealing with categorical variables, and offers greater parsimony due to the use of fewer parameters.

Compound truncated Poisson gamma distribution for understanding multimodal SAR intensities.

In recent years, many works have addressed the proposal of new probability models by theoretic and applied reasons. Specifically, mixture models have been indicated to describe phenomena whose resulting data impose high flexibility. One drawback of these tools is the high number of parameters involved, which implies hard inference procedures. To outperform this gap, we propose a new model that is able to describe multimodal behaviors with only three parameters, called compound truncated Poisson gamma (CTrPGa) distribution. Some properties of the CTrPGa law are derived and discussed: hazard, characteristic and cumulative functions and ordinary moments. Beyond, moment estimation, maximum likelihood estimation (via the expectation maximization algorithm) and empirical characteristic function methods for CTrPGa parameters are furnished. The first of them may be reduced to solve one nonlinear equation, which facilitates its use. We perform a simulation analysis to compare the performance of the three estimation methods studied. Moreover, since the gamma distribution and its mixture versions are commonly used to characterize synthetic aperture radar (SAR) intensities, we perform some real experiments with SAR imagery. The results present evidence that our model is a reasonable assumption that can be taken into account in the pre-processing step of such images.

Candidemia em dois hospitais terciários / Candidemia in two tertiary care hospitals

Objetivo: Determinar a incidência de candidemia nosocomial, as espécies prevalentes de Candida, as populações susceptíveis e o perfil de sensibilidade das espécies de Candida aos antifúngicos testados. Métodos: Realizou-se um estudo prospectivo, observacional, de base laboratorial, para avaliar a incidência de candidemia, as espécies/ distribuição de susceptibilidade e condições clínicas entre julho de 2007 e julho de 2008 em dois hospitais terciários privados em Recife, Brasil. Um caso de candidemia foi definido como o isolamento de Candida spp da cultura de sangue e um caso incidente como a primeira hemocultura positiva para Candida independente da espécie. Foram realizadas identificação das espécies e testes de susceptibilidade. As taxas de incidência foram calculadas por 1000 admissões. Resultados: Um total de 20870 pacientes foi admitido nos dois hospitais durante o período de estudo (hospital A: 17426 pacientes/192 leitos; hospital B: 3444 pacientes/50 leitos). Foram observados 41 episódios de candidemia (hospital A: 26; hospital B: 15) em 28 pacientes (hospital A: 16; hospital B: 12). A faixa etária foi de 26 dias a 92 anos (mediana de 60.8 anos). Cateter central esteve presente em 85.7% e em todos os episódios (100%) foi observado tratamento prévio com antibióticos. Candida albicans (n = 14), Candidaparapsilosis (n = 15), Candida tropicalis (n = 11) e Candida glabrata (n = 1) foram as espécies mais isoladas. Antifúngicos foram administrados em 37 episódios de candidemia (91.9% profilático e 75.7% tratamento). Todos os isolados foram sensíveis à anfotericina B, 43.9% ao voriconazol e 36.6% ao fluconazol. A taxa de incidência de candidemia foi de 1.34 episódios por 1 000 admissões (hospital A = 0.92; hospital B = 3.48). Treze pacientes (46.4%) morreram (84.6% > 60 anos). Conclusões: Candidemiafoi causada predominantemente por espécies não-albicans. A incidência de candidemia foi inferior ao observado em estudos multicêntricos brasileiros

Candida isolates in tertiary hospitals in northeastern Brazil

Candida is an opportunistic pathogen that affects highrisk patients who are either immunocompromised or critically ill and is associated with almost 80% of all nosocomial fungal infections, representing the major cause of fungemia with high mortality rates (40%). Candida albicans is the main cause of candidemia and among the non-albicans species C. parapsilosis, C. glabrata and C. tropicalis are the most frequent agents. The aim of this study was to evaluate the distribution of Candida species in two tertiary hospitals in Recife, Northeastern Brazil. It began by surveying all positive Candida cultures processed by the microbiology laboratory from September 2003 to September 2006. The cultures, originated from various types of biological material (blood, urine, tracheal, catheter and others), were processed by Vitec® system (Biomerieux SA, France). A total of 1.279 (hospital A: 837; hospital B: 442) sample isolates were positive for Candida. The most frequent species in both hospitals were: C. albicans (367), C. tropicalis (363), C. parapsilosis (147), C. glabrata (81), C. krusei (30) and C. guillermondii (14). The isolates were obtained from 746 hospitalized patients. A total of 221 positive hemocultures were detected in 166 different patients in both hospitals, and 113 (68.1%) of these patients with positive hemocultures presented Candida in other body sites.This study shows thatCandida non-albicans was the main isolated agent and evidences the importante of C. tropicalis in nosocomial fungal infections.

Candida é um patógeno oportunista que afeta pacientes de alto risco que estão também imunocomprometidos ou criticamente doentes, estando associada a quase 80% de todos os casos de infecções fúngicas nosocomiais, representando a maior causa de fungemia com alta taxa de mortalidade (40%). Candida albicans é a principal causa de candidemia e dentre as espécies não-albicans a C. parapsilosis, C. glabrata e C. tropicalis são os agentes mais frequentes. O objetivo deste estudo foi avaliar a distribuição das espécies de Candida em dois hospitais terciários no Recife, nordeste do Brasil. Foi realizado um levantamento de todas as culturas positivas para Candida processadas pelo laboratório de microbiologia de Setembro de 2003 a Setembro de 2006. Todas as culturas originadas de vários tipos de material biológico (sangue, urina, traquéia, catéter e outros) foram processadas pelo sistema Vitec® (Biomerrieux SA, France). Um total de 1.279 amostras (hospital A:837; hospital B: 442) foram positivas para Candida. As espécies mais frequentes em ambos os hospitais foram: C.albicans (367), C. tropicalis (363), C. parapsilosis (147), C. glabrata (81), C. krusei (30) e C. guillermondii (14). Os isolados foram obtidos de 746 pacientes hospitalizados. Um total de 221 hemoculturas positivas foram detectadas em 166 diferentes pacientes em ambos os hospitais, e 113 (68,1%) destes pacientes com hemoculturas positivas apresentavam Candida em outros locais do corpo. Este estudo mostrou que Candida não-albicans foi o principal agente isolado e prova a importância da C. tropicalis em infecções fúngicas nosocomiais.

Candida isolates in tertiary hospitals in northeastern Brazil / Isolados de Candida em hospital terciário no nordeste do Brasil

Candida is an opportunistic pathogen that affects highrisk patients who are either immunocompromised or critically ill and is associated with almost 80 percent of all nosocomial fungal infections, representing the major cause of fungemia with high mortality rates (40 percent). Candida albicans is the main cause of candidemia and among the non-albicans species C. parapsilosis, C. glabrata and C. tropicalis are the most frequent agents. The aim of this study was to evaluate the distribution of Candida species in two tertiary hospitals in Recife, Northeastern Brazil. It began by surveying all positive Candida cultures processed by the microbiology laboratory from September 2003 to September 2006. The cultures, originated from various types of biological material (blood, urine, tracheal, catheter and others), were processed by Vitec® system (Biomerieux SA, France). A total of 1.279 (hospital A: 837; hospital B: 442) sample isolates were positive for Candida. The most frequent species in both hospitals were: C. albicans (367), C. tropicalis (363), C. parapsilosis (147), C. glabrata (81), C. krusei (30) and C. guillermondii (14). The isolates were obtained from 746 hospitalized patients. A total of 221 positive hemocultures were detected in 166 different patients in both hospitals, and 113 (68.1%) of these patients with positive hemocultures presented Candida in other body sites.This study shows thatCandida non-albicans was the main isolated agent and evidences the importante of C. tropicalis in nosocomial fungal infections.

Candida é um patógeno oportunista que afeta pacientes de alto risco que estão também imunocomprometidos ou criticamente doentes, estando associada a quase 80% de todos os casos de infecções fúngicas nosocomiais, representando a maior causa de fungemia com alta taxa de mortalidade (40%). Candida albicans é a principal causa de candidemia e dentre as espécies não-albicans a C. parapsilosis, C. glabrata e C. tropicalis são os agentes mais frequentes. O objetivo deste estudo foi avaliar a distribuição das espécies de Candida em dois hospitais terciários no Recife, nordeste do Brasil. Foi realizado um levantamento de todas as culturas positivas para Candida processadas pelo laboratório de microbiologia de Setembro de 2003 a Setembro de 2006. Todas as culturas originadas de vários tipos de material biológico (sangue, urina, traquéia, catéter e outros) foram processadas pelo sistema Vitec® (Biomerrieux SA, France). Um total de 1.279 amostras (hospital A:837; hospital B: 442) foram positivas para Candida. As espécies mais frequentes em ambos os hospitais foram: C.albicans (367), C. tropicalis (363), C. parapsilosis (147), C. glabrata (81), C. krusei (30) e C. guillermondii (14). Os isolados foram obtidos de 746 pacientes hospitalizados. Um total de 221 hemoculturas positivas foram detectadas em 166 diferentes pacientes em ambos os hospitais, e 113 (68,1%) destes pacientes com hemoculturas positivas apresentavam Candida em outros locais do corpo. Este estudo mostrou que Candida não-albicans foi o principal agente isolado e prova a importância da C. tropicalis em infecções fúngicas nosocomiais.

Candida isolates in tertiary hospitals in northeastern Brazil.

Candida is an opportunistic pathogen that affects high-risk patients who are either immunocompromised or critically ill and is associated with almost 80% of all nosocomial fungal infections, representing the major cause of fungemia with high mortality rates (40%). Candida albicans is the main cause of candidemia and among the non-albicans species C. parapsilosis, C. glabrata and C. tropicalis are the most frequent agents. The aim of this study was to evaluate the distribution of Candida species in two tertiary hospitals in Recife, Northeastern Brazil. It began by surveying all positive Candida cultures processed by the microbiology laboratory from September 2003 to September 2006. The cultures, originated from various types of biological material (blood, urine, tracheal, catheter and others), were processed by Vitec (®) system (Biomerieux SA, France). A total of 1.279 (hospital A: 837; hospital B: 442) sample isolates were positive for Candida. The most frequent species in both hospitals were: C. albicans (367), C. tropicalis (363), C. parapsilosis (147), C. glabrata (81), C. krusei (30) and C. guillermondii (14). The isolates were obtained from 746 hospitalized patients. A total of 221 positive hemocultures were detected in 166 different patients in both hospitals, and 113 (68.1%) of these patients with positive hemocultures presented Candida in other body sites. This study shows that Candida non-albicans was the main isolated agent and evidences the importante of C. tropicalis in nosocomial fungal infections.

Candida isolates in tertiary hospitals in northeastern Brazil

Candida is an opportunistic pathogen that affects highrisk patients who are either immunocompromised or critically ill and is associated with almost 80% of all nosocomial fungal infections, representing the major cause of fungemia with high mortality rates (40%). Candida albicans is the main cause of candidemia and among the non-albicans species C. parapsilosis, C. glabrata and C. tropicalis are the most frequent agents. The aim of this study was to evaluate the distribution of Candida species in two tertiary hospitals in Recife, Northeastern Brazil. It began by surveying all positive Candida cultures processed by the microbiology laboratory from September 2003 to September 2006. The cultures, originated from various types of biological material (blood, urine, tracheal, catheter and others), were processed by Vitec® system (Biomerieux SA, France). A total of 1.279 (hospital A: 837; hospital B: 442) sample isolates were positive for Candida. The most frequent species in both hospitals were: C. albicans (367), C. tropicalis (363), C. parapsilosis (147), C. glabrata (81), C. krusei (30) and C. guillermondii (14). The isolates were obtained from 746 hospitalized patients. A total of 221 positive hemocultures were detected in 166 different patients in both hospitals, and 113 (68.1%) of these patients with positive hemocultures presented Candida in other body sites.This study shows thatCandida non-albicans was the main isolated agent and evidences the importante of C. tropicalis in nosocomial fungal infections.

Candida é um patógeno oportunista que afeta pacientes de alto risco que estão também imunocomprometidos ou criticamente doentes, estando associada a quase 80% de todos os casos de infecções fúngicas nosocomiais, representando a maior causa de fungemia com alta taxa de mortalidade (40%). Candida albicans é a principal causa de candidemia e dentre as espécies não-albicans a C. parapsilosis, C. glabrata e C. tropicalis são os agentes mais frequentes. O objetivo deste estudo foi avaliar a distribuição das espécies de Candida em dois hospitais terciários no Recife, nordeste do Brasil. Foi realizado um levantamento de todas as culturas positivas para Candida processadas pelo laboratório de microbiologia de Setembro de 2003 a Setembro de 2006. Todas as culturas originadas de vários tipos de material biológico (sangue, urina, traquéia, catéter e outros) foram processadas pelo sistema Vitec® (Biomerrieux SA, France). Um total de 1.279 amostras (hospital A:837; hospital B: 442) foram positivas para Candida. As espécies mais frequentes em ambos os hospitais foram: C.albicans (367), C. tropicalis (363), C. parapsilosis (147), C. glabrata (81), C. krusei (30) e C. guillermondii (14). Os isolados foram obtidos de 746 pacientes hospitalizados. Um total de 221 hemoculturas positivas foram detectadas em 166 diferentes pacientes em ambos os hospitais, e 113 (68,1%) destes pacientes com hemoculturas positivas apresentavam Candida em outros locais do corpo. Este estudo mostrou que Candida não-albicans foi o principal agente isolado e prova a importância da C. tropicalis em infecções fúngicas nosocomiais.

[Candidemia in a tertiary hospital in northeastern Brazil]. / Candidemia em hospital terciário do nordeste do Brasil.

We conducted a prospective, observational, laboratory-based study on candidemia to investigate the incidence of candidemia, species distribution and clinical conditions between September 2003 and March 2004 in a private tertiary hospital in Recife, northeastern Brazil. Cases of candidemia were defined as occurrences of isolation of Candida spp from blood cultures. The incidence rate was calculated per 1,000 admissions. A total of 5,532 patients were admitted to the hospital during the study period, and 1,745 blood cultures were processed. Twenty-one episodes of candidemia were observed in 18 patients. The incidence rate of candidemia was 3.9 episodes per 1,000 admissions. Non-albicans species accounted for more than 50% of the cases, and Candida parapsilosis (33%) and Candida tropicalis (24%) predominated. Eleven (61%) patients died. The incidence of candidemia was higher than that observed in a Brazilian multicenter study. Candidemia was caused predominantly by non-albicans species.

Candidemia em hospital terciário do nordeste do Brasil / Candidemia in a tertiary hospital in northeastern Brazil

Realizou-se um estudo observacional, prospectivo, de base laboratorial, para investigar a incidência de candidemia, distribuição de espécies e condições clínicas entre setembro 2003 e março 2004, em um hospital privado terciário em Recife, Nordeste do Brasil. Um caso de candidemia foi definido como isolamento de Candida spp de hemocultura. A taxa de incidência foi calculada por 1.000 admissões. Um total de 5.532 pacientes foram admitidos no hospital durante o período de estudo, e 1.745 culturas de sangue foram processadas. Foram observados 21 episódios de candidemia em 18 pacientes. A taxa de incidência de candidemia foi de 3,9 episódios por 1.000 admissões. Espécies não-albicans representaram mais de 50 por cento dos casos, predominando Candida parapsilosis (33 por cento) e Candida tropicalis (24 por cento). Onze (61 por cento) pacientes morreram. A incidência de candidemia foi mais alta que aquela observada em estudo multicêntrico brasileiro. Candidemia foi predominantemente causada por espécies não-albicans.

We conducted a prospective, observational, laboratory-based study on candidemia to investigate the incidence of candidemia, species distribution and clinical conditions between September 2003 and March 2004 in a private tertiary hospital in Recife, northeastern Brazil. Cases of candidemia were defined as occurrences of isolation of Candida spp from blood cultures. The incidence rate was calculated per 1,000 admissions. A total of 5,532 patients were admitted to the hospital during the study period, and 1,745 blood cultures were processed. Twenty-one episodes of candidemia were observed in 18 patients. The incidence rate of candidemia was 3.9 episodes per 1,000 admissions. Non-albicans species accounted for more than 50 percent of the cases, and Candida parapsilosis (33 percent) and Candida tropicalis (24 percent) predominated. Eleven (61 percent) patients died. The incidence of candidemia was higher than that observed in a Brazilian multicenter study. Candidemia was caused predominantly by non-albicans species.