We sought to determine if the prevalence of antibiotic-resistant Escherichia coli differed across retail poultry products and among major production categories, including organic, "raised without ...antibiotics", and conventional.
We collected all available brands of retail chicken and turkey-including conventional, "raised without antibiotic", and organic products-every two weeks from January to December 2012. In total, E. coli was recovered from 91% of 546 turkey products tested and 88% of 1367 chicken products tested. The proportion of samples contaminated with E. coli was similar across all three production categories. Resistance prevalence varied by meat type and was highest among E. coli isolates from turkey for the majority of antibiotics tested. In general, production category had little effect on resistance prevalence among E. coli isolates from chicken, although resistance to gentamicin and multidrug resistance did vary. In contrast, resistance prevalence was significantly higher for 6 of the antibiotics tested-and multidrug resistance-among isolates from conventional turkey products when compared to those labelled organic or "raised without antibiotics". E. coli isolates from chicken varied strongly in resistance prevalence among different brands within each production category.
The high prevalence of resistance among E. coli isolates from conventionally-raised turkey meat suggests greater antimicrobial use in conventional turkey production as compared to "raised without antibiotics" and organic systems. However, among E. coli from chicken meat, resistance prevalence was more strongly linked to brand than to production category, which could be caused by brand-level differences during production and/or processing, including variations in antimicrobial use.
The skin microbiome is a complex ecosystem with important implications for cutaneous health and disease. Topical antibiotics and antiseptics are often employed to preserve the balance of this ...population and inhibit colonization by more pathogenic bacteria. However, despite their widespread use, the impact of these interventions on broader microbial communities remains poorly understood. Here, we report the longitudinal effects of topical antibiotics and antiseptics on skin bacterial communities and their role in
colonization resistance. In response to antibiotics, cutaneous populations exhibited an immediate shift in bacterial residents, an effect that persisted for multiple days posttreatment. By contrast, antiseptics elicited only minor changes to skin bacterial populations, with few changes to the underlying microbiota. While variable in scope, both antibiotics and antiseptics were found to decrease colonization by commensal
spp. by sequencing- and culture-based methods, an effect which was highly dependent on baseline levels of
Because
residents have been shown to compete with the skin pathogen
, we also tested whether treatment could influence
levels at the skin surface. We found that treated mice were more susceptible to exogenous association with
and that precolonization with the same
residents that were previously disrupted by treatment reduced
levels by over 100-fold. In all, the results of this study indicate that antimicrobial drugs can alter skin bacterial residents and that these alterations can have critical implications for cutaneous host defense.
E. coli
ST131 is an important extraintestinal pathogen that can colonize the gastrointestinal tracts of humans and food animals. Here, we combined detection of accessory traits associated with avian ...adaptation (ColV plasmids) with high-resolution phylogenetics to quantify the portion of human infections caused by ST131 strains of food animal origin. Our results suggest that one ST131 sublineage—ST131-
H
22—has become established in poultry populations around the world and that meat may serve as a vehicle for human exposure and infection. ST131-
H
22 is just one of many
E. coli
lineages that may be transmitted from food animals to humans. Additional studies that combine detection of host-associated accessory elements with phylogenetics may allow us to quantify the total fraction of human extraintestinal infections attributable to food animal
E. coli
strains.
Escherichia coli
sequence type 131 (ST131) has emerged rapidly to become the most prevalent extraintestinal pathogenic
E. coli
clones in circulation today. Previous investigations appeared to exonerate retail meat as a source of human exposure to ST131; however, these studies focused mainly on extensively multidrug-resistant ST131 strains, which typically carry allele 30 of the
fimH
type 1 fimbrial adhesin gene (ST131-
H
30). To estimate the frequency of extraintestinal human infections arising from foodborne ST131 strains without bias toward particular sublineages or phenotypes, we conducted a 1-year prospective study of
E. coli
from meat products and clinical cultures in Flagstaff, Arizona. We characterized all isolates by multilocus sequence typing,
fimH
typing, and core genome phylogenetic analyses, and we screened isolates for avian-associated ColV plasmids as an indication of poultry adaptation.
E. coli
was isolated from 79.8% of the 2,452 meat samples and 72.4% of the 1,735 culture-positive clinical samples. Twenty-seven meat isolates were ST131 and belonged almost exclusively (
n
= 25) to the ST131-
H
22 lineage. All but 1 of the 25 H22 meat isolates were from poultry products, and all but 2 carried poultry-associated ColV plasmids. Of the 1,188 contemporaneous human clinical
E. coli
isolates, 24 were ST131-
H
22, one-quarter of which occurred in the same high-resolution phylogenetic clades as the ST131-
H
22 meat isolates and carried ColV plasmids. Molecular clock analysis of an international ST131-
H
22 genome collection suggested that ColV plasmids have been acquired at least six times since the 1940s and that poultry-to-human transmission is not limited to the United States.
The skin harbors complex communities of resident microorganisms, yet little is known of their physiological roles and the molecular mechanisms that mediate cutaneous host-microbe interactions. Here, ...we profiled skin transcriptomes of mice reared in the presence and absence of microbiota to elucidate the range of pathways and functions modulated in the skin by the microbiota.
A total of 2820 genes were differentially regulated in response to microbial colonization and were enriched in gene ontology (GO) terms related to the host-immune response and epidermal differentiation. Innate immune response genes and genes involved in cytokine activity were generally upregulated in response to microbiota and included genes encoding toll-like receptors, antimicrobial peptides, the complement cascade, and genes involved in IL-1 family cytokine signaling and homing of T cells. Our results also reveal a role for the microbiota in modulating epidermal differentiation and development, with differential expression of genes in the epidermal differentiation complex (EDC). Genes with correlated co-expression patterns were enriched in binding sites for the transcription factors Klf4, AP-1, and SP-1, all implicated as regulators of epidermal differentiation. Finally, we identified transcriptional signatures of microbial regulation common to both the skin and the gastrointestinal tract.
With this foundational approach, we establish a critical resource for understanding the genome-wide implications of microbially mediated gene expression in the skin and emphasize prospective ways in which the microbiome contributes to skin health and disease.
Background/Objectives
Acne, a common pediatric disease, tends to be more comedonal in preadolescents, whereas older individuals are more likely to have inflammatory lesions in addition to comedones. ...Thus the microbiome of preadolescents may be different. In this pilot study we aimed to characterize the preadolescent acne microbiome, compare the microbiome in preadolescents with and without acne, and investigate changes in the microbiome after topical treatment with benzoyl peroxide or a retinoid in a small cohort of preadolescents.
Methods
Participants were 7‐10 years of age with (intervention group) or without (control group) acne and were recruited during routine outpatient dermatology visits. Baseline questionnaires, physical examination, and pore strip application were performed for all participants. Intervention group participants were randomized to receive topical therapy with benzoyl peroxide 5% gel or cream or tretinoin 0.025% cream. Participants with acne were followed up 8‐10 weeks later and pore strip application was repeated.
Results
Preadolescents with acne were colonized with a greater diversity of cutaneous bacteria than controls and the most commonly identified bacterium was Streptococcus. The number of bacterial species and phylogenetic diversity decreased after treatment with benzoyl peroxide and tretinoin.
Conclusion
The predominant bacteria in microbiome studies of adult acne is Propionibacterium, whereas in this pediatric population we saw a lot of Streptococcus bacteria. After treatment, the microbiomes of intervention group participants more closely resembled those of control group participants.
Chronic wounds are a major complication of diabetes associated with high morbidity and health care expenditures. To investigate the role of colonizing microbiota in diabetic wound healing, clinical ...outcomes, and response to interventions, we conducted a longitudinal, prospective study of patients with neuropathic diabetic foot ulcers (DFU). Metagenomic shotgun sequencing revealed that strain-level variation of Staphylococcus aureus and genetic signatures of biofilm formation were associated with poor outcomes. Cultured wound isolates of S. aureus elicited differential phenotypes in mouse models that corresponded with patient outcomes, while wound “bystanders” such as Corynebacterium striatum and Alcaligenes faecalis, typically considered commensals or contaminants, also significantly impacted wound severity and healing. Antibiotic resistance genes were widespread, and debridement, rather than antibiotic treatment, significantly shifted the DFU microbiota in patients with more favorable outcomes. These findings suggest that the DFU microbiota may be a marker for clinical outcomes and response to therapeutic interventions.
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•Wound microbiota was profiled longitudinally in patients with diabetic foot ulcers•Staphylococcus aureus strains were associated with poor outcomes•S. aureus and other wound isolates promoted differential wound healing responses•Debridement depleted anaerobic bacteria in wounds with favorable outcomes
Kalan et al. investigate the role of colonizing microbiota in wound healing, clinical outcomes, and response to therapy in patients with chronic diabetic wounds. Strains of the wound pathogen S. aureus were associated with poor outcomes, and sharp debridement therapy depleted anaerobic bacteria in wounds with favorable outcomes.
The epidermis forms a barrier that defends the body from desiccation and entry of harmful substances, while also sensing and integrating environmental signals. The tightly orchestrated cellular ...changes needed for the formation and maintenance of this epidermal barrier occur in the context of the skin microbiome. Using germ-free mice, we demonstrate the microbiota is necessary for proper differentiation and repair of the epidermal barrier. These effects are mediated by microbiota signaling through the aryl hydrocarbon receptor (AHR) in keratinocytes, a xenobiotic receptor also implicated in epidermal differentiation. Mice lacking keratinocyte AHR are more susceptible to barrier damage and infection, during steady-state and epicutaneous sensitization. Colonization with a defined consortium of human skin isolates restored barrier competence in an AHR-dependent manner. We reveal a fundamental mechanism whereby the microbiota regulates skin barrier formation and repair, which has far-reaching implications for the numerous skin disorders characterized by epidermal barrier dysfunction.
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•Germ-free mice have abnormal skin barrier structure and function•Keratinocyte aryl hydrocarbon receptor (AHR) mediates barrier function and repair•Human skin commensal microbes activate keratinocyte AHR•Targeting the microbiota-AHR axis promotes skin barrier repair in disease models
A self-renewing skin barrier is needed for terrestrial life. Uberoi et al. demonstrate that the skin microbiota regulates barrier repair and integrity by activating keratinocyte aryl hydrocarbon receptor (AHR). This microbiota-AHR axis was targeted with a defined consortium of human skin commensals to improve barrier repair in disease models.
Microbial burden of chronic wounds is believed to play an important role in impaired healing and the development of infection-related complications. However, clinical cultures have little predictive ...value of wound outcomes, and culture-independent studies have been limited by cross-sectional design and small cohort size. We systematically evaluated the temporal dynamics of the microbiota colonizing diabetic foot ulcers, a common and costly complication of diabetes, and its association with healing and clinical complications. Dirichlet multinomial mixture modeling, Markov chain analysis, and mixed-effect models were used to investigate shifts in the microbiota over time and their associations with healing. Here we show, to our knowledge, previously unreported temporal dynamics of the chronic wound microbiome. Microbiota community instability was associated with faster healing and improved outcomes. Diabetic foot ulcer microbiota were found to exist in one of four community types that experienced frequent and nonrandom transitions. Transition patterns and frequencies were associated with healing time. Exposure to systemic antibiotics destabilized the wound microbiota, rather than altering overall diversity or relative abundance of specific taxa. This study provides evidence that the dynamic wound microbiome is indicative of clinical outcomes and may be a valuable guide for personalized management and treatment of chronic wounds.
Despite critical functions in cutaneous health and disease, it is unclear how resident skin microbial communities are altered by topical antimicrobial interventions commonly used in personal and ...clinical settings. Here we show that acute exposure to antiseptic treatments elicits rapid but short-term depletion of microbial community diversity and membership. Thirteen subjects were enrolled in a longitudinal treatment study to analyze the effects of topical treatments (i.e., ethanol, povidone-iodine, chlorhexidine, and water) on the skin microbiome at two skin sites of disparate microenvironment: forearm and back. Treatment effects were highly dependent on personalized and body site–specific colonization signatures, which concealed community dynamics at the population level when not accounted for in this analysis. The magnitude of disruption was influenced by the identity and abundance of particular bacterial inhabitants. Lowly abundant members of the skin microbiota were more likely to be displaced, and subsequently replaced, by the most abundant taxa prior to treatment. Members of the skin commensal family Propionibactericeae were particularly resilient to treatment, suggesting a distinct competitive advantage in the face of disturbance. These results provide insight into the stability and resilience of the skin microbiome, while establishing the impact of topical antiseptic treatment on skin bacterial dynamics and community ecology.
Background. Klebsiella pneumoniae is a common colonizer of the gastrointestinal tract of humans, companion animals, and livestock. To better understand potential contributions of foodborne K. ...pneumoniae to human clinical infections, we compared K. pneumoniae isolates from retail meat products and human clinical specimens to assess their similarity based on antibiotic resistance, genetic relatedness, and virulence. Methods. Klebsiella pneumoniae was isolated from retail meats from Flagstaff grocery stores in 2012 and from urine and blood specimens from Flagstaff Medical Center in 2011–2012. Isolates underwent antibiotic susceptibility testing and whole-genome sequencing. Genetic relatedness of the isolates was assessed using multilocus sequence typing and phylogenetic analyses. Extraintestinal virulence of several closely related meat-source and urine isolates was assessed using a murine sepsis model. Results. Meat-source isolates were significantly more likely to be multidrug resistant and resistant to tetracycline and gentamicin than clinical isolates. Four sequence types occurred among both meat-source and clinical isolates. Phylogenetic analyses confirmed close relationships among meat-source and clinical isolates. Isolates from both sources showed similar virulence in the mouse sepsis model. Conclusions. Meat-source K. pneumoniae isolates were more likely than clinical isolates to be antibiotic resistant, which could reflect selective pressures from antibiotic use in food-animal production. The close genetic relatedness of meat-source and clinical isolates, coupled with similarities in virulence, suggest that the barriers to transmission between these 2 sources are low. Taken together, our results suggest that retail meat is a potential vehicle for transmitting virulent, antibiotic-resistant K. pneumoniae from food animals to humans.
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