Quorum sensing (QS) is a widespread process in bacteria that employs autoinducing chemical signals to coordinate diverse, often cooperative activities such as bioluminescence, biofilm formation, and ...exoenzyme secretion. Signaling via acyl-homoserine lactones is the paradigm for QS in Proteobacteria and is particularly well understood in the opportunistic pathogen Pseudomonas aeruginosa. Despite thirty years of mechanistic research, empirical studies have only recently addressed the benefits of QS and provided support for the traditional assumptions regarding its social nature and its role in optimizing cell-density-dependent group behaviors. QS-controlled public-goods production has served to investigate principles that explain the evolution and stability of cooperation, including kin selection, pleiotropic constraints, and metabolic prudence. With respect to medical application, appreciating social dynamics is pertinent to understanding the efficacy of QS-inhibiting drugs and the evolution of resistance. Future work will provide additional insight into the foundational assumptions of QS and relate laboratory discoveries to natural ecosystems.
Cooperative behaviors provide a collective benefit, but are considered costly for the individual. Here, we report that these costs vary dramatically in different contexts and have opposing effects on ...the selection for non-cooperating cheaters. We investigate a prominent example of bacterial cooperation, the secretion of the peptide siderophore pyoverdine by Pseudomonas aeruginosa, under different nutrient-limiting conditions. Using metabolic modeling, we show that pyoverdine incurs a fitness cost only when its building blocks carbon or nitrogen are growth-limiting and are diverted from cellular biomass production. We confirm this result experimentally with a continuous-culture approach. We show that pyoverdine non-producers (cheaters) enjoy a large fitness advantage in co-culture with producers (cooperators) and spread to high frequency when limited by carbon, but not when limited by phosphorus. The principle of nutrient-dependent fitness costs has implications for the stability of cooperation in pathogenic and non-pathogenic environments, in biotechnological applications, and beyond the microbial realm.Cooperative behaviour among individuals provides a collective benefit, but is considered costly. Using Pseudomonas aeruginosa as a model system, the authors show that secretion of the siderophore pyoverdine only incurs a fitness cost and favours cheating when its building blocks carbon or nitrogen are growth-limiting.
Despite widespread use of antibiotics for the treatment of life-threatening infections and for research on the role of commensal microbiota, our understanding of their effects on the host is still ...very limited.
Using a popular mouse model of microbiota depletion by a cocktail of antibiotics, we analysed the effects of antibiotics by combining intestinal transcriptome together with metagenomic analysis of the gut microbiota. In order to identify specific microbes and microbial genes that influence the host phenotype in antibiotic-treated mice, we developed and applied analysis of the transkingdom network.
We found that most antibiotic-induced alterations in the gut can be explained by three factors: depletion of the microbiota; direct effects of antibiotics on host tissues and the effects of remaining antibiotic-resistant microbes. Normal microbiota depletion mostly led to downregulation of different aspects of immunity. The two other factors (antibiotic direct effects on host tissues and antibiotic-resistant microbes) primarily inhibited mitochondrial gene expression and amounts of active mitochondria, increasing epithelial cell death. By reconstructing and analysing the transkingdom network, we discovered that these toxic effects were mediated by virulence/quorum sensing in antibiotic-resistant bacteria, a finding further validated using in vitro experiments.
In addition to revealing mechanisms of antibiotic-induced alterations, this study also describes a new bioinformatics approach that predicts microbial components that regulate host functions and establishes a comprehensive resource on what, why and how antibiotics affect the gut in a widely used mouse model of microbiota depletion by antibiotics.
is an emerging fungal threat that has been spreading in the United States since it was first reported in 2016.
To describe recent changes in the U.S. epidemiology of
occurring from 2019 to 2021.
...Description of national surveillance data.
United States.
Persons with any specimen that was positive for
.
Case counts reported to the Centers for Disease Control and Prevention by health departments, volume of colonization screening, and antifungal susceptibility results were aggregated and compared over time and by geographic region.
A total of 3270 clinical cases and 7413 screening cases of
were reported in the United States through 31 December 2021. The percentage increase in clinical cases grew each year, from a 44% increase in 2019 to a 95% increase in 2021. Colonization screening volume and screening cases increased in 2021 by more than 80% and more than 200%, respectively. From 2019 to 2021, 17 states identified their first
case. The number of
cases that were resistant to echinocandins in 2021 was about 3 times that in each of the previous 2 years.
Identification of screening cases depends on screening that is done on the basis of need and available resources. Screening is not conducted uniformly across the United States, so the true burden of
cases may be underestimated.
cases and transmission have risen in recent years, with a dramatic increase in 2021. The rise in echinocandin-resistant cases and evidence of transmission is particularly concerning because echinocandins are first-line therapy for invasive
infections, including
. These findings highlight the need for improved detection and infection control practices to prevent spread of
.
None.
The emerging yeast
can be highly drug resistant, causing invasive infections, and large outbreaks.
went from an unknown pathogen a decade ago to being reported in over thirty countries on six ...continents.
consists of four discrete clades, based on where the first isolates of the clade were reported, South Asian (clade I), East Asian (clade II), African (clade III), and South American (clade IV). These clades have unique genetic and biochemical characteristics that are important to understand and inform the global response to
Clade II has been underrepresented in the literature despite being the first one discovered. In this issue of the
, Y. J. Kwon et al. (J Clin Microbiol 57:e01624-18, 2019, https://doi.org/10.1128/JCM.01624-18) describe the largest collection of clinical isolates from Clade II, which is also the longest-running span of clinical cases, 20 years, from any single region to date. Clade II appears to have a propensity for the ear that is uncharacteristic of the other clades, which typically cause invasive infections and large-scale outbreaks. This study provides new information on an understudied lineage of
and has important implications for future surveillance.
Candida auris is a fungal pathogen of high concern due to its ability to cause healthcare-associated infections and outbreaks, its resistance to antimicrobials and disinfectants and its persistence ...on human skin and in the inanimate environment. To inform surveillance and future mitigation strategies, we defined the extent of skin colonization and explored the microbiome associated with C. auris colonization. We collected swab specimens and clinical data at three times points between January and April 2019 from 57 residents (up to ten body sites each) of a ventilator-capable skilled nursing facility with endemic C. auris and routine chlorhexidine gluconate (CHG) bathing. Integrating microbial-genomic and epidemiologic data revealed occult C. auris colonization of multiple body sites not targeted commonly for screening. High concentrations of CHG were associated with suppression of C. auris growth but not with deleterious perturbation of commensal microbes. Modeling human mycobiome dynamics provided insight into underlying alterations to the skin fungal community as a possible modifiable risk factor for acquisition and persistence of C. auris. Failure to detect the extensive, disparate niches of C. auris colonization may reduce the effectiveness of infection-prevention measures that target colonized residents, highlighting the importance of universal strategies to reduce C. auris transmission.
Volatile organic compounds (VOCs) are known to be produced by a wide range of micro‐organisms and for a number of purposes. Volatile‐based microbial inhibition in environments such as soil is ...well‐founded, with numerous antimicrobial VOCs having been identified. Inhibitory VOCs are of interest as microbial control agents, as low concentrations of gaseous VOCs can elicit significant antimicrobial effects. Volatile organic compounds are organic chemicals typically characterized as having low molecular weight, low solubility in water, and high vapour pressure. Consequently, VOCs readily evaporate to the gaseous phase at standard temperature and pressure. This contact‐independent antagonism presents unique advantages over traditional, contact‐dependent microbial control methods, including increased surface exposure and reduced environmental persistence. This approach has been the focus of our recent research, with positive results suggesting it may be particularly promising for the management of emerging fungal pathogens, such as the causative agents of white‐nose syndrome of bats and snake fungal disease, which are difficult or impossible to treat using traditional approaches. Here, we review the history of volatile‐based microbial control, discuss recent progress in formulations that mimic naturally antagonistic VOCs, outline the development of a novel treatment device, and highlight areas where further work is needed to successfully deploy VOCs against existing and emerging fungal pathogens.
Abstract
Background
Since the identification of the first 2 Candida auris cases in Chicago, Illinois, in 2016, ongoing spread has been documented in the Chicago area. We describe C. auris emergence ...in high-acuity, long-term healthcare facilities and present a case study of public health response to C. auris and carbapenemase-producing organisms (CPOs) at one ventilator-capable skilled nursing facility (vSNF-A).
Methods
We performed point prevalence surveys (PPSs) to identify patients colonized with C. auris and infection-control (IC) assessments and provided ongoing support for IC improvements in Illinois acute- and long-term care facilities during August 2016–December 2018. During 2018, we initiated a focused effort at vSNF-A and conducted 7 C. auris PPSs; during 4 PPSs, we also performed CPO screening and environmental sampling.
Results
During August 2016–December 2018 in Illinois, 490 individuals were found to be colonized or infected with C. auris. PPSs identified the highest prevalence of C. auris colonization in vSNF settings (prevalence, 23–71%). IC assessments in multiple vSNFs identified common challenges in core IC practices. Repeat PPSs at vSNF-A in 2018 identified increasing C. auris prevalence from 43% to 71%. Most residents screened during multiple PPSs remained persistently colonized with C. auris. Among 191 environmental samples collected, 39% were positive for C. auris, including samples from bedrails, windowsills, and shared patient-care items.
Conclusions
High burden in vSNFs along with persistent colonization of residents and environmental contamination point to the need for prioritizing IC interventions to control the spread of C. auris and CPOs.
This report describes Candida auris emergence in Chicago during August 2016–December 2018, and public health response at one ventilator-capable skilled nursing facility with high colonization burden. Improved adherence to infection control and environmental disinfection is needed to control spread.
Cell-cell communication, also termed quorum sensing (QS), is a widespread process that coordinates gene expression in bacterial populations. The generally accepted view is that QS optimizes the cell ...density-dependent benefit attained from cooperative behaviors, often in the form of secreted products referred to as "public goods." This view is challenged by an increasing number of cell-associated products or "private goods" reported to be under QS-control for which a collective benefit is not apparent. A prominent example is nucleoside hydrolase from
, a periplasmic enzyme that catabolizes adenosine. Several recent studies have shown that private goods can function to stabilize cooperation by co-regulated public goods, seemingly explaining their control by QS. Here we argue that this property is a by-product of selection for other benefits rather than an adaptation. Emphasizing ecophysiological context, we propose alternative explanations for the QS control of private goods. We suggest that the benefit attained from private goods is associated with high cell density, either because a relevant ecological condition correlates with density, or because the private good is, directly or indirectly, involved in cooperative behavior. Our analysis helps guide a systems approach to QS, with implications for antivirulence drug design and synthetic biology.
Abstract
Candida auris is an emerging, multidrug-resistant yeast that can spread rapidly in healthcare settings. Phenotypic switching has been observed in other Candida species and can potentially ...interfere with correct identification. The aim of this study is to address misidentification of C. auris by describing alternate phenotypes after broth enrichment and subculturing on CHROMagar Candida. Each isolate displayed different frequencies of phenotypic switching, suggesting a strain to strain variability. Increased knowledge of the multiple phenotypes of C. auris increases the chance of isolating and identifying C. auris by reducing the risk of discarding false negative alternate colony morphologies.
PDF
