“Tolerance” of Misused Terminology? Enforcing Standardized Phenotypic Definitions

Dimitrijovski, Borce; Jensen, Slade O.; Espedido, Björn A.; Hal, Sebastiaan J. van

doi:10.1128/mbio.00446-15

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…This is particularly relevant for listeriosis, as gentamicin is the most common secondary antibiotic used for treatment (Temple and Nahata, 2000). While the SCV E18 showed no increase in MIC for the other antibiotics tested, indicating a lack of acquired resistance, it was nonetheless able to survive lethal concentrations of norfloxacin, ampicillin (up to 48 h), co-trimoxazole, and vancomycin significantly better than the wild type, which taken together, are the definition of antibiotic tolerance (Dimitrijovski et al, 2015). The increase in tolerance toward vancomycin, second generation fluoroquinolones (e.g., norfloxacin) and betalactams (e.g., ampicillin) has been observed with S. aureus SCVs and is presumably the result of their slow growing SCV phenotype (Chuard et al, 1997;Garcia et al, 2012;.…”

Section: Discussionmentioning

confidence: 96%

Antimicrobial Resistance and Virulence Common Mechanisms

Giraud

Rychlı́k²,

Cloeckaert

2017

Frontiers Research Topics

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Frontiers is more than just an open-access publisher of scholarly articles: it is a pioneering approach to the world of academia, radically improving the way scholarly research is managed. The grand vision of Frontiers is a world where all people have an equal opportunity to seek, share and generate knowledge. Frontiers provides immediate and permanent online open access to all its publications, but this alone is not enough to realize our grand goals. Frontiers Journal SeriesThe Frontiers Journal Series is a multi-tier and interdisciplinary set of open-access, online journals, promising a paradigm shift from the current review, selection and dissemination processes in academic publishing. All Frontiers journals are driven by researchers for researchers; therefore, they constitute a service to the scholarly community. At the same time, the Frontiers Journal Series operates on a revolutionary invention, the tiered publishing system, initially addressing specific communities of scholars, and gradually climbing up to broader public understanding, thus serving the interests of the lay society, too. Dedication to QualityEach Frontiers article is a landmark of the highest quality, thanks to genuinely collaborative interactions between authors and review editors, who include some of the world's best academicians. Research must be certified by peers before entering a stream of knowledge that may eventually reach the public -and shape society; therefore, Frontiers only applies the most rigorous and unbiased reviews. Frontiers revolutionizes research publishing by freely delivering the most outstanding research, evaluated with no bias from both the academic and social point of view. By applying the most advanced information technologies, Frontiers is catapulting scholarly publishing into a new generation. What are Frontiers Research Topics?Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial

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Section: Discussionmentioning

confidence: 96%

Antimicrobial Resistance and Virulence Common Mechanisms

Giraud

Rychlı́k²,

Cloeckaert

2017

Frontiers Research Topics

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show abstract

“…This is particularly relevant for listeriosis, as gentamicin is the most common secondary antibiotic used for treatment ( Temple and Nahata, 2000 ). While the SCV E18 showed no increase in MIC for the other antibiotics tested, indicating a lack of acquired resistance, it was nonetheless able to survive lethal concentrations of norfloxacin, ampicillin (up to 48 h), co-trimoxazole, and vancomycin significantly better than the wild type, which taken together, are the definition of antibiotic tolerance ( Dimitrijovski et al, 2015 ). The increase in tolerance toward vancomycin, second generation fluoroquinolones (e.g., norfloxacin) and beta-lactams (e.g., ampicillin) has been observed with S. aureus SCVs and is presumably the result of their slow growing SCV phenotype ( Chuard et al, 1997 ; Garcia et al, 2012 ; Lechner et al, 2012 ).…”

Section: Discussionmentioning

confidence: 99%

The Small Colony Variant of Listeria monocytogenes Is More Tolerant to Antibiotics and Has Altered Survival in RAW 264.7 Murine Macrophages

2016

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Small Colony Variant (SCV) cells of bacteria are a slow-growing phenotype that result from specific defects in the electron transport chain. They form pinpoint colonies on agar plates and have a variety of phenotypic characteristics, such as altered carbon metabolism, decreased toxin and lytic enzyme production, aminoglycoside resistance, and increased intracellular persistence. They are clinically relevant in Staphylococcus aureus and Pseudomonas aeruginosa, serving as a reservoir for recurrent or prolonged infections. Here, we found that a SCV mutant in the foodborne pathogen Listeria monocytogenes (strain SCV E18), similar to the high persister mutant phenotype, survived significantly better than the wild type when exposed over a 48-h period to concentrations above Minimal Inhibitory Concentration for most tested antibiotics. SCV E18 survived more poorly than the wildtype in unactivated RAW264.7 macrophage cells, presumably because of its reduced listeriolysin O expression, however, it survived better in reactive oxygen species producing, phorbol 12-myristate 13-acetate-activated macrophages. Although SCV E18 was sensitive to oxygen as it entered the stationary phase, it was significantly more tolerant to H2O2 than the wild type, which may result from a shift in metabolism, however, further investigation is needed to resolve this. SCV E18 is a spontaneous mutant with a point mutation in the hemA gene. A wild type copy of hemA was complemented on plasmid pSOG30222, which restored the wild type phenotype. The results reported here suggest that the SCV of L. monocytogenes could be of clinical importance and highlight a need for adequate clinical screening for this phenotype, as it could affect antibiotic treatment outcomes.

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“…Regarding terminology, Dimitrijovski and colleagues ( 1 ) express concern that our use of the term “tolerance” is not in accord with what they state is the “official definition” by the Clinical and Laboratory Standards Institute (CLSI) of “a vancomycin-tolerant strain as one for which the minimum bactericidal concentration (MBC)-to-MIC ratio is >32 after 24 h of incubation.” We certainly agree to the importance of having uniform terminology; however, we are not aware that the testing standards developed by CLSI to accomplish their stated mission of facilitating comparison of data from different laboratories have been adopted as part of an “official” nomenclature, and in fact not all references cited by Dimitrijovski et al adhere to what they have termed the official definition. In any case, as explained in the text of our paper ( 2 ), our use of the term “tolerance” was intended to distinguish noninherited, reduced antibiotic susceptibility from resistance, which commonly is used to indicate inherited reduced susceptibility that is mutational in origin (for example, also see reference 3 ).…”

Section: Replymentioning

confidence: 99%