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. 2008;3(11):e3749.
doi: 10.1371/journal.pone.0003749. Epub 2008 Nov 18.

A reservoir of drug-resistant pathogenic bacteria in asymptomatic hosts

Gabriel G Perron  1 , Sylvain Quessy, Graham Bell
Affiliations

A reservoir of drug-resistant pathogenic bacteria in asymptomatic hosts

Gabriel G Perron et al. PLoS One. 2008.

Abstract

The population genetics of pathogenic bacteria has been intensively studied in order to understand the spread of disease and the evolution of virulence and drug resistance. However, much less attention has been paid to bacterial carriage populations, which inhabit hosts without producing disease. Since new virulent strains that cause disease can be recruited from the carriage population of bacteria, our understanding of infectious disease is seriously incomplete without knowledge on the population structure of pathogenic bacteria living in an asymptomatic host. We report the first extensive survey of the abundance and diversity of a human pathogen in asymptomatic animal hosts. We have found that asymptomatic swine from livestock productions frequently carry populations of Salmonella enterica with a broad range of drug-resistant strains and genetic diversity greatly exceeding that previously described. This study shows how agricultural practice and human intervention may lead and influence the evolution of a hidden reservoir of pathogens, with important implications for human health.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Frequency of Salmonella strains isolated from asymptomatic swine by territories.
Figure 2
Figure 2. Frequency of antibiotic-resistant strains of Salmonella among isolates from asymptomatic swine.
Antibiotics are: Ax, co-amoxiclav; Am, ampicillin; Ap, apramycin; Cfx, cefoxitin; Ct, ceftiotur; Ce, cefalotin; Cm, chloramphenicol; Ne, neomycin; Te, tetracycline; TS, trimethoprim-sulfas.
Figure 3
Figure 3. Maximum likelihood tree representing the twenty sequence types associated with asymptomatic swine.
The number of isolates (in brackets) and the percentage of the most frequent serotype are shown.
See this image and copyright information in PMC

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