RESUMEN
A freshwater enterobacterial population (N = 111) was studied for antimicrobial and mercury resistance patterns, and for its possible association with biotic and abiotic factors in that environment. Conventional biochemical tests identified Klebsiella sp, Morganella sp, Serratia sp, Escherichia sp, Enterobacter sp, Edwarsiella sp, Proteus sp, Citrobacter sp, Providencia sp, and Kluyvera sp. There was no correlation between antimicrobial resistance patterns of isolates and bacterial genera, but resistance patterns varied among water samples and between seasons. Resistance to multiple antimicrobials was common (61%). The percentage of bacteria resistant to at least one antimicrobial differed between the rainy (100%) and dry seasons (89%). Resistance to beta-lactams and chloramphenicol was the most frequent and resistance to amikacin, gentamicin and kanamycin was less frequent. The main water variables examined (abiotic factors pH and temperature; biotic factor chlorophyll a concentration) did not influence antimicrobial resistance. Significant impact on freshwater enterobacteria, as evidenced by antimicrobial-multiple resistance and by the presence of bla(TEM) gene, may point to the fact that it has an important role in horizontal spread of resistance.
Asunto(s)
Antiinfecciosos/farmacología , Farmacorresistencia Bacteriana , Enterobacteriaceae/efectos de los fármacos , Enterobacteriaceae/metabolismo , Microbiología del Agua , Brasil , Cloranfenicol/farmacología , Clorofila/química , Clorofila A , Concentración de Iones de Hidrógeno , Mercurio/toxicidad , Modelos Estadísticos , Oxígeno/química , Reacción en Cadena de la Polimerasa , Temperatura , beta-Lactamasas/metabolismo , beta-Lactamas/farmacologíaRESUMEN
We isolated cDNA sequences coding for dermonecrotic/sphingomyelinases factor proteins from the brown spider Loxosceles intermedia, here named Loxtox proteins. The amino acid sequences based on cloned cDNA of several Loxtox proteins revealed at least six distinct groups of proteins expressed in the venom gland. The level of similarity among the toxins varied from 99% to 55%. The finding of several isoforms of Loxtox in the venom of this spider may reflect an evolutionary adaptation for different prey types and reinforces the idea of an efficient mutational mechanism in the venom gland of spiders.
Asunto(s)
Hidrolasas Diéster Fosfóricas/química , Esfingomielina Fosfodiesterasa/metabolismo , Venenos de Araña/química , Arañas/metabolismo , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , ADN Complementario/genética , Regulación de la Expresión Génica , Datos de Secuencia Molecular , Hidrolasas Diéster Fosfóricas/metabolismo , Filogenia , ARN Mensajero/genética , Esfingomielina Fosfodiesterasa/genética , Venenos de Araña/metabolismoRESUMEN
A freshwater enterobacterial population (N = 111) was studied for antimicrobial and mercury resistance patterns, and for its possible association with biotic and abiotic factors in that environment. Conventional biochemical tests identified Klebsiella sp, Morganella sp, Serratia sp, Escherichia sp, Enterobacter sp, Edwarsiella sp, Proteus sp, Citrobacter sp, Providencia sp, and Kluyvera sp. There was no correlation between antimicrobial resistance patterns of isolates and bacterial genera, but resistance patterns varied among water samples and between seasons. Resistance to multiple antimicrobials was common (61%). The percentage of bacteria resistant to at least one antimicrobial differed between the rainy (100%) and dry seasons (89%). Resistance to â-lactams and chloramphenicol was the most frequent and resistance to amikacin, gentamicin and kanamycin was less frequent. The main water variables examined (abiotic factors pH and temperature; biotic factor chlorophyll a concentration) did not influence antimicrobial resistance. Significant impact on freshwater enterobacteria, as evidenced by antimicrobial-multiple resistance and by the presence of blaTEM gene, may point to the fact that it has an important role in horizontal spread of resistance.