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Complementarity of selective culture and qPCR for colistin resistance screening in fresh and frozen pig caecum samples

Investigation published in Frontiers in Microbiology

November 9th, 2020

Retrospective studies involving the screening of frozen stored collections of samples are commonplace when a new threat emerges, but it has been demonstrated that the freeze-thaw process can affect bacterial viability. The study of colistin-resistant bacteria in human and animal samples is an example of this issue. In this study we compared culture-based and PCR-based methods for analysing both relative occurrence and diversity of colistin-resistant bacteria in caecal samples to determine the most appropriate method for frozen samples. Thus, 272 isolates from the caecal contents of healthy pigs were tested before and after a six-month freezing period. A selective medium was used when traditional isolation of colistin-resistant bacteria was tested, while a real-time SYBR Green PCR assay was applied for mcr-1 quantification. The number of samples with colistin-resistant isolates was higher in fresh samples (247/272) than in frozen ones (67/272) and also showed a higher diversity of colistin-resistant genera. PCR identification of mcr colistin resistance genes evidenced that mcr-1 was the most prevalent mcr gene and mcr-2 was detected for the first time in pigs from Spanish animal production. The number of samples with mcr-1-carrying bacteria after a freezing period decreased, while real-time quantitation of the mcr-1 gene showed similar values in frozen and fresh samples. Therefore, when frozen caecal samples need to be analysed, molecular detection of DNA could be the best option to provide a highly representative frame of the initial population present in the sample, and culture-based methods might be a useful complement to study colistin resistance levels




Miguela-Villoldo P., Moreno MA., Hernandez M., Rodriguez-Lazaro D., Gallardo A., Borge C., Quesada A., Dominguez L. and Ugarte-Ruiz M..




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Complementarity of selective culture and qPCR for colistin resistance screening in fresh and frozen pig caecum samples

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Complementarity of selective culture and qPCR for colistin resistance screening in fresh and frozen pig caecum samples



Participants:

Universidad ComplutenseServicio de Zoonosis de Transmisión Alimentaria y Resistencia a Antimicrobianos (ZTA). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM).

Universidad ComplutenseDepartamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM).

Instituto Tecnológico Agrario de Castilla y LeónInstituto Tecnológico Agrario de Castilla y León (ITACyL).

Universidad de BurgosUniversidad de Burgos (UBU).

Universidad de ExtremaduraFacultad de Veterinaria. Universidad de Extremadura (UNEX).

Universidad de CórdobaFacultad de Veterinaria. Universidad de Córdoba (UCO).

Universidad de ExtremaduraInstituto Universitario de Biotecnología Ganadera y Cinegética (INBIO G+C). Universidad de Extremadura (UNEX).







Frontiers in Microbiology
FACTOR YEAR Q
5.640 2020

NLMID: 101548977

PMID: 33240230

ISSN: 1664-302X



TITLE: Complementarity of selective culture and qPCR for colistin resistance screening in fresh and frozen pig caecum samples


JOURNAL: Front Microbiol


NUMERACIÓN: 11:572712


AÑO: 2020


PUBLISHER: Frontiers Research Foundation


AUTHORS: Miguela-Villoldo P., Moreno MA., Hernandez M., Rodriguez-Lazaro D., Gallardo A., Borge C., Quesada A., Dominguez L. and Ugarte-Ruiz M..


First
Pedro Miguela Villoldo
4th
Alfonso David Rodríguez Lázaro
8th
Lucas Domínguez Rodríguez
Last
María Ugarte Ruiz

DOI: https://doi.org/10.3389/fmicb.2020.572712


CITE THIS PUBLICATION:

Miguela-Villoldo P., Moreno MA., Hernandez M., Rodriguez-Lazaro D., Gallardo A., Borge C., Quesada A., Dominguez L. and Ugarte-Ruiz M. Complementarity of selective culture and qPCR for colistin resistance screening in fresh and frozen pig caecum samples. Frontiers in Microbiology. 11:572712. 2020. (A). ISSN: 1664-302X. DOI: 10.3389/fmicb.2020.572712


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