RESUMO
In this paper, we present a new fractional epidemiological model on a heterogeneous network to investigate Middle East respiratory syndrome (MERS-CoV), which is caused by a virus in the coronavirus family. We also consider the development of equations for the camel population, given that it is the primary animal source of the virus, as well as direct human interaction with this population. The model is configured in an SIS form for both the human population and the camel population. We study the equilibrium positions of the system and the conditions for the existence of each of them, as well as the local stability of each equilibrium position. Then, we provide some numerical examples that compare real data and numerical results.
Assuntos
Infecções por Coronavirus , Coronavírus da Síndrome Respiratória do Oriente Médio , Animais , Humanos , Camelus , Infecções por Coronavirus/epidemiologia , Modelos EpidemiológicosRESUMO
As is well known the novel coronavirus (COVID-19) is a zoonotic virus and our model is concerned with the effect of the zoonotic source of the coronavirus during the outbreak in China. We present a SEIS complex network epidemic model for the novel coronavirus. Our model is presented in fractional form and with varying population. The steady states and the basic reproductive number are calculated. We also present some numerical examples and the sensitivity analysis of the basic reproductive number for the parameters.
RESUMO
In this paper we present a fractional order generalization of Perelson et al. basic hepatitis C virus (HCV) model including an immune response term. We argue that fractional order equations are more suitable than integer order ones in modeling complex systems which include biological systems. The model is presented and discussed. Also we argue that the added immune response term represents some basic properties of the immune system and that it should be included to study longer term behavior of the disease.
RESUMO
In the study presented here, the genetic characteristics of methicillin-susceptible Staphylococcus aureus (MSSA) strains isolated from patients attending hospitals in the city of Córdoba, Argentina, during 1999-2002 were evaluated to determine their genetic relationship with methicillin-resistant S. aureus (MRSA) clones as part of an effort to control the potential emergence of new epidemic MRSA strains. The results showed there is a high frequency of MSSA strains carrying Panton-Valentine leukocidin genes in invasive infections in Córdoba, Argentina, particularly in those occurring in hospital settings. Panton-Valentine leukocidin genes were found in the genomic background of one clone (ST30-N pulsotype) belonging to a successful internationally distributed MSSA lineage (clonal complex 30), which is closely related to the EMRSA-16 pandemic clone. These genes were also detected in the ancestral clone (ST5-M pulsotype) of the most prevalent MRSA epidemic clone causing healthcare-associated infections in this region, known as the Cordobes/Chilean clone. The molecular characterization of circulating MSSA strains, including the detection of Panton-Valentine leukocidin genes, is thus a useful marker for investigating the evolving epidemiology of hospital- and community-acquired MRSA clones.
Assuntos
Toxinas Bacterianas/genética , Exotoxinas/genética , Leucocidinas/genética , Resistência a Meticilina/genética , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Adolescente , Adulto , Idoso , Argentina/epidemiologia , Técnicas de Tipagem Bacteriana , Criança , Pré-Escolar , Infecções Comunitárias Adquiridas/epidemiologia , Infecções Comunitárias Adquiridas/microbiologia , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Eletroforese em Gel de Campo Pulsado/métodos , Transferência Genética Horizontal/genética , Humanos , Lactente , Testes de Sensibilidade Microbiana/métodos , Pessoa de Meia-Idade , Infecções Estafilocócicas/epidemiologia , Staphylococcus aureus/isolamento & purificaçãoRESUMO
V. cholerae non-O1 non-O139 serogroups isolated from clinical and environmental sources in Córdoba, Argentina, were analyzed for the presence and expression of virulence genes. Most of the strains studied contained the genes toxR and hlyA, but lacked ctxA, zot, ace, tcpA and stn. The culture supernatants were tested for hemolytic and cytotoxic activity. The enterotoxic potential of the strains was studied in a rabbit ileal loop assay and their genetic profiles were compared by PFGE. The environmental strains varied in their virulence phenotype and showed no-clonal relationships. The clinical strains were highly enterotoxic, hemolytic, proteolytic and showed indistinguishable PFGE profiles, although they differed in their cytotoxic activity. This is the first description, using cell culture and “in vivo” studies, of the virulence properties of non-O1 non-O139 V. cholerae from Argentina.
En este trabajo se analizó la presencia y expresión de genes de virulencia en V. cholerae no-O1 no-O139 de origen clínico y ambiental, aislados en Córdoba, Argentina. La mayoría de las cepas estudiadas contiene los genes toxR y hlyA, pero no ctxA, zot, ace, tcpA y stn. Se analizó la actividad hemolítica y citotóxica de estas cepas en los sobrenadantes de cultivo, así como su potencial enterotóxico en ensayos de asa ileal ligada de conejo. Además, los aislamientos fueron comparados por sus perfiles genéticos en PFGE. Las cepas del medio ambiente mostraron variación en su fenotipo de virulencia y no mostraron relación clonal. Las cepas clínicas fueron muy enterotóxicas, hemolíticas, proteolíticas y mostraron perfiles indistinguibles de PFGE, aunque mostraron diferencias en su actividad citotóxica. En este trabajo se describen por primera vez, utilizando ensayos de cultivo celular e “in vivo”, propiedades de virulencia de V. cholerae no-O1 no-O139 aislados en Argentina.
Assuntos
Animais , Humanos , Coelhos , Vibrio cholerae não O1/patogenicidade , Argentina/epidemiologia , Técnicas de Tipagem Bacteriana , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/fisiologia , Chlorocebus aethiops , Células COS/microbiologia , Toxina da Cólera/genética , DNA Bacteriano/genética , Farmacorresistência Bacteriana , Diarreia/epidemiologia , Diarreia/microbiologia , Eletroforese em Gel de Campo Pulsado , Enterotoxinas/genética , Enterotoxinas/isolamento & purificação , Enterotoxinas/fisiologia , Deleção de Genes , Genes Bacterianos , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/isolamento & purificação , Proteínas Hemolisinas/fisiologia , Metaloendopeptidases/genética , Metaloendopeptidases/isolamento & purificação , Metaloendopeptidases/fisiologia , Filogenia , Vibrioses/epidemiologia , Vibrioses/microbiologia , Vibrio cholerae não O1/efeitos dos fármacos , Vibrio cholerae não O1/genética , Vibrio cholerae não O1/isolamento & purificação , Virulência/genética , Microbiologia da ÁguaRESUMO
V. cholerae non-O1 non-O139 serogroups isolated from clinical and environmental sources in Córdoba, Argentina, were analyzed for the presence and expression of virulence genes. Most of the strains studied contained the genes toxR and hlyA, but lacked ctxA, zot, ace, tcpA and stn. The culture supernatants were tested for hemolytic and cytotoxic activity. The enterotoxic potential of the strains was studied in a rabbit ileal loop assay and their genetic profiles were compared by PFGE. The environmental strains varied in their virulence phenotype and showed no clonal relationships. The clinical strains were highly enterotoxic, hemolytic, proteolytic and showed indistinguishable PFGE profiles, although they differed in their cytotoxic activity. This is the first description, using cell culture and "in vivo" studies, of the virulence properties of non-O1 non-O139 V. cholerae from Argentina.
Assuntos
Vibrio cholerae não O1/patogenicidade , Animais , Argentina/epidemiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/fisiologia , Técnicas de Tipagem Bacteriana , Células COS/microbiologia , Chlorocebus aethiops , Toxina da Cólera/genética , DNA Bacteriano/genética , Diarreia/epidemiologia , Diarreia/microbiologia , Farmacorresistência Bacteriana , Eletroforese em Gel de Campo Pulsado , Enterotoxinas/genética , Enterotoxinas/isolamento & purificação , Enterotoxinas/fisiologia , Deleção de Genes , Genes Bacterianos , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/isolamento & purificação , Proteínas Hemolisinas/fisiologia , Humanos , Metaloendopeptidases/genética , Metaloendopeptidases/isolamento & purificação , Metaloendopeptidases/fisiologia , Filogenia , Coelhos , Vibrioses/epidemiologia , Vibrioses/microbiologia , Vibrio cholerae não O1/efeitos dos fármacos , Vibrio cholerae não O1/genética , Vibrio cholerae não O1/isolamento & purificação , Virulência/genética , Microbiologia da ÁguaRESUMO
V. cholerae non-O1 non-O139 serogroups isolated from clinical and environmental sources in Córdoba, Argentina, were analyzed for the presence and expression of virulence genes. Most of the strains studied contained the genes toxR and hlyA, but lacked ctxA, zot, ace, tcpA and stn. The culture supernatants were tested for hemolytic and cytotoxic activity. The enterotoxic potential of the strains was studied in a rabbit ileal loop assay and their genetic profiles were compared by PFGE. The environmental strains varied in their virulence phenotype and showed no clonal relationships. The clinical strains were highly enterotoxic, hemolytic, proteolytic and showed indistinguishable PFGE profiles, although they differed in their cytotoxic activity. This is the first description, using cell culture and [quot ]in vivo[quot ] studies, of the virulence properties of non-O1 non-O139 V. cholerae from Argentina.
RESUMO
The aim of the present study was to investigate the presence of extended-spectrum beta-lactamases (ESBL) in Klebsiella pneumoniae isolated at the "Hospital de Niños de Córdoba". The strains were collected from inpatients between January 1996 and July 2000. A total of 150 ESBL producer isolates were detected. During 1996 the prevalence of ESBL producer K. pneumoniae was 20%, but since 1998 the values have increased to approximately 60%. Phenotypic analysis such as isoelectric point (pl) and antibiotyping performed in 32 randomly selected isolates showed two different enzyme profiles: 81% had ESBL with pl = 7.9 and preferential activity against cefotaxime, while 19% showed ESBL with pl = 5.4 and preferential activity against ceftazidime. No isolates resistant to imipenem or ciprofloxacin were detected. Susceptibility to other antimicrobial agents varied, but resistance to gentamicin was strongly associated with ESBL producer isolates. Resistance determinants could be transferred to Escherichia coli by conjugation assays.
Assuntos
Proteínas de Bactérias/isolamento & purificação , Infecção Hospitalar/microbiologia , Farmacorresistência Bacteriana Múltipla , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/enzimologia , Resistência beta-Lactâmica , beta-Lactamases/isolamento & purificação , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Argentina/epidemiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Criança , Conjugação Genética , Infecção Hospitalar/epidemiologia , Farmacorresistência Bacteriana Múltipla/genética , Hospitais Pediátricos , Humanos , Ponto Isoelétrico , Infecções por Klebsiella/epidemiologia , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/isolamento & purificação , Fenótipo , Prevalência , Estudos Retrospectivos , Especificidade por Substrato , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , beta-Lactamases/metabolismo , beta-LactamasRESUMO
El objetivo de este estudio fue investigar la presencia de ß-lactamasas de espectro extendido (BLEE) en Klebsiella pneumoniae aisladas en el Hospital de Niños de Córdoba. Las cepas fueron obtenidas de pacientes internados entre enero de 1996 y julio de 2000. Se encontró un total de 150 aislamientos productores de BLEE. En el año 1996 la prevalencia de BLEE en K.pneumoniae fue del 20 por ciento, mientras que desde 1998 se ha mantenido en valores próximos al 60 por ciento. Estudios fenotípicos como la determinación del punto isoeléctrico (pl) y el antibiotipo realizados sobre un grupo de 32 aislamientos seleccionados al azar demostraron la presencia de dos tipos de enzimas. El 81 por ciento mostró una BLEE con pl=7,9 y mayor actividad sobre cefotaxima y el 19 por ciento restante presentó una BLEE con pl=5,4 y mayor actividad sobre ceftacidima. No se detectaron aislamientos resistentes a imipenem ni a ciprofloxacina. La sensibilidad a otras drogas fue variable, siendo muy frecuente la resistencia asociada a gentamicina. Los determinantes de resistencia pudieron transferirse por conjugación a Escherichia coli.
Assuntos
Criança , Argentina , beta-Lactamases , Cefalosporinas , Resistência Microbiana a Medicamentos , Klebsiella pneumoniaeRESUMO
El objetivo de este estudio fue investigar la presencia de ß-lactamasas de espectro extendido (BLEE) en Klebsiella pneumoniae aisladas en el Hospital de Niños de Córdoba. Las cepas fueron obtenidas de pacientes internados entre enero de 1996 y julio de 2000. Se encontró un total de 150 aislamientos productores de BLEE. En el año 1996 la prevalencia de BLEE en K.pneumoniae fue del 20 por ciento, mientras que desde 1998 se ha mantenido en valores próximos al 60 por ciento. Estudios fenotípicos como la determinación del punto isoeléctrico (pl) y el antibiotipo realizados sobre un grupo de 32 aislamientos seleccionados al azar demostraron la presencia de dos tipos de enzimas. El 81 por ciento mostró una BLEE con pl=7,9 y mayor actividad sobre cefotaxima y el 19 por ciento restante presentó una BLEE con pl=5,4 y mayor actividad sobre ceftacidima. No se detectaron aislamientos resistentes a imipenem ni a ciprofloxacina. La sensibilidad a otras drogas fue variable, siendo muy frecuente la resistencia asociada a gentamicina. Los determinantes de resistencia pudieron transferirse por conjugación a Escherichia coli. (AU)
Assuntos
Criança , Klebsiella pneumoniae , beta-Lactamases , Resistência Microbiana a Medicamentos , Cefalosporinas , ArgentinaRESUMO
The aim of the present study was to investigate the presence of extended-spectrum beta-lactamases (ESBL) in Klebsiella pneumoniae isolated at the [quot ]Hospital de Niños de Córdoba[quot ]. The strains were collected from inpatients between January 1996 and July 2000. A total of 150 ESBL producer isolates were detected. During 1996 the prevalence of ESBL producer K. pneumoniae was 20
, but since 1998 the values have increased to approximately 60
. Phenotypic analysis such as isoelectric point (pl) and antibiotyping performed in 32 randomly selected isolates showed two different enzyme profiles: 81
had ESBL with pl = 7.9 and preferential activity against cefotaxime, while 19
showed ESBL with pl = 5.4 and preferential activity against ceftazidime. No isolates resistant to imipenem or ciprofloxacin were detected. Susceptibility to other antimicrobial agents varied, but resistance to gentamicin was strongly associated with ESBL producer isolates. Resistance determinants could be transferred to Escherichia coli by conjugation assays.
