Most cited article - PubMed ID 34987223
Emergence of methicillin resistance predates the clinical use of antibiotics
Antibiotic resistance is a priority public health problem resulting from eco-evolutionary dynamics within microbial communities and their interaction at a mammalian host interface or geographical scale. The links between mammalian host genetics, bacterial gut community, and antimicrobial resistance gene (ARG) content must be better understood in natural populations inhabiting heterogeneous environments. Hybridization, the interbreeding of genetically divergent populations, influences different components of the gut microbial communities. However, its impact on bacterial traits such as antibiotic resistance is unknown. Here, we present that hybridization might shape bacterial communities and ARG occurrence. We used amplicon sequencing to study the gut microbiome and to predict ARG composition in natural populations of house mice (Mus musculus). We compared gastrointestinal bacterial and ARG diversity, composition, and abundance across a gradient of pure and hybrid genotypes in the European House Mouse Hybrid Zone. We observed an increased overall predicted richness of ARG in hybrid mice. We found bacteria-ARG interactions by their co-abundance and detected phenotypes of extreme abundances in hybrid mice at the level of specific bacterial taxa and ARGs, mainly multidrug resistance genes. Our work suggests that mammalian host genetic variation impacts the gut microbiome and chromosomal ARGs. However, it raises further questions on how the mammalian host genetics impact ARGs via microbiome dynamics or environmental covariates.
- Keywords
- antimicrobial resistance gene, hybridization, mice, microbiome,
- Publication type
- Journal Article MeSH
Considering its very short elimination half-life, the approved oxacillin dosage might not be sufficient to maintain the pharmacokinetic/pharmacodynamics (PK/PD) target of time-dependent antibiotics. This study aimed to describe the population pharmacokinetics of oxacillin and to explore the probability of PK/PD target attainment by using various dosing regimens with oxacillin in staphylococcal infections. Both total and unbound oxacillin plasma concentrations retrieved as a part of routine therapeutic drug-monitoring practice were analyzed using nonlinear mixed-effects modeling. Monte Carlo simulations were used to generate the theoretical distribution of unbound oxacillin plasma concentration-time profiles at various dosage regimens. Data from 24 patients treated with oxacillin for staphylococcal infection have been included into the analysis. The volume of distribution of oxacillin in the population was 11.2 L, while the elimination rate constant baseline of 0.73 h-1 increased by 0.3 h-1 with each 1 mL/s/1.73 m2 of the estimated glomerular filtration rate (eGFR). The median value of oxacillin binding to plasma proteins was 86%. The superiority of continuous infusion in achieving target PK/PD values was demonstrated and dosing according to eGFR was proposed. Daily oxacillin doses of 9.5 g, 11 g, or 12.5 g administered by continuous infusion have been shown to be optimal for achieving target PK/PD values in patients with moderate, mild, or normal renal function, respectively.
- Keywords
- Monte Carlo simulations, antibiotics, dosing regimen, glomerular filtration rate, nonlinear mixed-effects modeling, oxacillin,
- Publication type
- Journal Article MeSH
Trichophyton erinacei is a main cause of dermatophytosis in hedgehogs and is increasingly reported from human infections worldwide. This pathogen was originally described in the European hedgehog (Erinaceus europaeus) but is also frequently found in the African four-toed hedgehog (Atelerix albiventris), a popular pet animal worldwide. Little is known about the taxonomy and population genetics of this pathogen despite its increasing importance in clinical practice. Notably, whether there are different populations or even cryptic species associated with different hosts or geographic regions is not known. To answer these questions, we collected 161 isolates, performed phylogenetic and population-genetic analyses, determined mating-type, and characterised morphology and physiology. Multigene phylogeny and microsatellite analysis supported T. erinacei as a monophyletic species, in contrast to highly incongruent single-gene phylogenies. Two main subpopulations, one specific mainly to Atelerix and second to Erinaceus hosts, were identified inside T. erinacei, and slight differences in the size of microconidia and antifungal susceptibilities were observed among them. Although the process of speciation into two lineages is ongoing in T. erinacei, there is still gene flow between these populations. Thus, we present T. erinacei as a single species, with notable intraspecies variability in genotype and phenotype. The data from wild hedgehogs indicated that sexual reproduction in T. erinacei and de novo infection of hedgehogs from soil are probably rare events and that clonal horizontal spread strongly dominates. The molecular typing approach used in this study represents a suitable tool for further epidemiological surveillance of this emerging pathogen in both animals and humans. The results of this study also highlighted the need to use a multigene phylogeny ideally in combination with other independent molecular markers to understand the species boundaries of dermatophytes. Citation: Čmoková A, Kolařík M, Guillot J, et al. 2022. Host-driven subspeciation in the hedgehog fungus, Trichophyton erinacei, an emerging cause of human dermatophytosis. Persoonia 48: 203-218. https://doi.org/10.3767/persoonia.2022.48.06.
