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1.
J Water Health ; 19(3): 436-447, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-34152296

RESUMEN

Giardia duodenalis and Cryptosporidium spp. are two of the most prominent aetiological agents of waterborne diseases. Therefore, efficient and affordable methodologies for identifying and quantifying these parasites in water are increasingly necessary. USEPA Method 1623.1 is a widely used and validated protocol for detecting these parasites in water samples. It consists of a concentration step, followed by parasite purification and visualization by immunofluorescence microscopy. Although efficient, this method has a high cost particularly due to the immunomagnetic separation (IMS) step, which is most needed with complex and highly contaminated samples. Based on this, the present study aimed to determine whether it is possible to maintain the efficiency of Method 1623.1 while reducing the amount of beads per reaction, using as a matrix the challenge water recommended by the World Health Organization. As for Giardia cysts, a satisfactory recovery efficiency (RE) was obtained using 50% less IMS beads. This was evaluated both with a commercial cyst suspension (56.1% recovery) and an analytical quality assessment (47.5% recovery). Although RE rates obtained for Cryptosporidium parvum did not meet Method 1623.1 criteria in any of the experimental conditions tested, results presented in this paper indicated the relevance of the described adaptations, even in challenge water.


Asunto(s)
Criptosporidiosis , Cryptosporidium , Animales , Separación Inmunomagnética , Oocistos , Agua
2.
Sci Rep ; 8(1): 16691, 2018 11 12.
Artículo en Inglés | MEDLINE | ID: mdl-30420658

RESUMEN

Clostridium difficile virulence is driven primarily by the processes of toxinogenesis and sporulation, however many in vitro experimental systems for studying C. difficile physiology have arguably limited relevance to the human colonic environment. We therefore created a more physiologically-relevant model of the colonic milieu to study gut pathogen biology, incorporating human faecal water (FW) into growth media and assessing the physiological effects of this on C. difficile strain 630. We identified a novel set of C. difficile-derived metabolites in culture supernatants, including hexanoyl- and pentanoyl-amino acid derivatives by LC-MSn. Growth of C. difficile strain 630 in FW media resulted in increased cell length without altering growth rate and RNA sequencing identified 889 transcripts as differentially expressed (p < 0.001). Significantly, up to 300-fold increases in the expression of sporulation-associated genes were observed in FW media-grown cells, along with reductions in motility and toxin genes' expression. Moreover, the expression of classical stress-response genes did not change, showing that C. difficile is well-adapted to this faecal milieu. Using our novel approach we have shown that interaction with FW causes fundamental changes in C. difficile biology that will lead to increased disease transmissibility.


Asunto(s)
Clostridioides difficile/fisiología , Clostridioides difficile/patogenicidad , Adaptación Fisiológica/fisiología , Bacillus subtilis/metabolismo , Bacillus subtilis/patogenicidad , Bacillus subtilis/fisiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Cromatografía Liquida , Clostridioides difficile/metabolismo , Heces/microbiología , Regulación Bacteriana de la Expresión Génica , Espectrometría de Masas , Análisis de Secuencia de ARN , Esporas Bacterianas/metabolismo , Esporas Bacterianas/patogenicidad , Esporas Bacterianas/fisiología , Transcriptoma/genética , Virulencia
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