scholarly journals Bacterial biofilms predominate in both acute and chronic human lung infections

Thorax ◽  
2022 ◽  
pp. thoraxjnl-2021-217576
Author(s):  
Mette Kolpen ◽  
Kasper Nørskov Kragh ◽  
Juan Barraza Enciso ◽  
Daniel Faurholt-Jepsen ◽  
Birgitte Lindegaard ◽  
...  
Keyword(s):  
Human Infection ◽  
Growth Media ◽  
Bacterial Disease ◽  
Chronic Infections ◽  
Biofilm Growth ◽  
Fast Growing ◽  
Acute Infections ◽  
Patient Groups ◽  
Lung Infections ◽  
Infection Types

BackgroundA basic paradigm of human infection is that acute bacterial disease is caused by fast growing planktonic bacteria while chronic infections are caused by slow-growing, aggregated bacteria, a phenomenon known as a biofilm. For lung infections, this paradigm has been thought to be supported by observations of how bacteria proliferate in well-established growth media in the laboratory—the gold standard of microbiology.ObjectiveTo investigate the bacterial architecture in sputum from patients with acute and chronic lung infections.MethodsAdvanced imaging technology was used for quantification and direct comparison of infection types on fresh sputum samples, thereby directly testing the acute versus chronic paradigm.ResultsIn this study, we compared the bacterial lifestyle (planktonic or biofilm), growth rate and inflammatory response of bacteria in freshly collected sputum (n=43) from patient groups presenting with acute or chronic lung infections. We found that both acute and chronic lung infections are dominated by biofilms (aggregates of bacteria within an extracellular matrix), although planktonic cells were observed in both sample types. Bacteria grew faster in sputum from acute infections, but these fast-growing bacteria were enriched in biofilms similar to the architecture thought to be reserved for chronic infections. Cellular inflammation in the lungs was also similar across patient groups, but systemic inflammatory markers were only elevated in acute infections.ConclusionsOur findings indicate that the current paradigm of equating planktonic with acute and biofilm with chronic infection needs to be revisited as the difference lies primarily in metabolic rates, not bacterial architecture.

scholarly journals Antibiotics drive expansion of rare pathogens in a chronic infection microbiome model

2021 ◽  
Author(s):  
John J Varga ◽  
Conan Zhao ◽  
Jacob D Davis ◽  
Yiqi Hao ◽  
Jennifer M Farrell ◽  
...  
Keyword(s):  
Chronic Infection ◽  
Treatment Strategies ◽  
Opportunistic Pathogens ◽  
Chronic Infections ◽  
Causal Inferences ◽  
Resistant Species ◽  
Pathogen Dynamics ◽  
Acute Infections ◽  
Competitive Release ◽  
Lung Infections

Chronic (long-lasting) infections are globally a major and rising cause of morbidity and mortality. Unlike typical acute infections, chronic infections are ecologically diverse, characterized by the presence of a polymicrobial mix of opportunistic pathogens and human-associated commensals. To address the challenge of chronic infection microbiomes, we focus on a particularly well-characterized disease, cystic fibrosis (CF), where polymicrobial lung infections persist for decades despite frequent exposure to antibiotics. Epidemiological analyses point to conflicting results on the benefits of antibiotic treatment, and are confounded by the dependency of antibiotic exposures on prior pathogen presence, limiting their ability to draw causal inferences on the relationships between antibiotic exposure and pathogen dynamics. To address this limitation, we develop a synthetic infection microbiome model, and benchmark on clinical data. We show that, in the absence of antibiotics, the microbiome structure in a synthetic sputum medium is highly repeatable and dominated by oral commensals. In contrast, challenge with physiologically relevant antibiotic doses leads to substantial community perturbation characterized by multiple alternate pathogen-dominant states and enrichment of drug-resistant species. These results provide evidence that antibiotics can drive the expansion (via competitive release) of previously rare opportunistic pathogens and offer a path towards microbiome-informed conditional treatment strategies.

scholarly journals Polygenic adaptation, clonal interference, and the evolution of mutators in experimental Pseudomonas aeruginosa populations

2021 ◽  
Author(s):  
Katrina B. Harris ◽  
Kenneth M. Flynn ◽  
Vaughn S. Cooper
Keyword(s):  
Genetic Diversity ◽  
Pseudomonas Aeruginosa ◽  
Genetic Variation ◽  
Phenotypic Diversity ◽  
Large Fraction ◽  
Growth Media ◽  
Chronic Infections ◽  
Clonal Interference ◽  
Biofilm Growth ◽  
Bacterial Populations

AbstractIn bacterial populations, switches in lifestyle from motile, planktonic growth to surface-grown biofilm is associated with persistence in both infections and non-clinical biofilms. Studies have identified the first steps of adaptation to biofilm growth but have yet to replicate the extensive genetic diversity observed in chronic infections or in the natural environment. We conducted a 90-day long evolution experiment with Pseudomonas aeruginosa PA14 in growth media that promotes biofilm formation in either planktonic culture or in a biofilm bead model. Surprisingly, all populations evolved extensive genetic diversity with hundreds of mutations maintained at intermediate frequencies, while fixation events were rare. Instead of the expected few beneficial mutations rising in frequency through successive sweeps, we observe a remarkable 40 genes with parallel mutations spanning both environments and often on coexisting genotypes within a population. Additionally, the evolution of mutator genotypes (mutS or mutL mutator alleles) that rise to high frequencies in as little as 25 days contribute to the extensive genetic variation and strong clonal interference. Parallelism in several transporters (including pitA, pntB, nosD, and pchF) indicate probable adaptation to the arginine media that becomes highly alkaline during growth. Further, genes involved in signal transduction (including gacS, aer2, bdlA, and PA14_71750) reflect likely adaptations to biofilm-inducing conditions. This experiment shows how extensive genetic and phenotypic diversity can arise and persist in microbial populations despite strong selection that would normally purge diversity.ImportanceHow biodiversity arises and is maintained in clonally reproducing organisms like microbes remains unclear. Many models presume that beneficial genotypes will outgrow others and purge variation via selective sweeps. Environmental structure like biofilms may oppose this process and preserve variation. We tested this hypothesis by evolving P. aeruginosa populations in biofilm-promoting media for three months and found both adaptation and diversification that were mostly uninterrupted by fixation events that eliminate diversity. Genetic variation tended to be greater in lines grown using a bead model of biofilm growth but many lineages also persisted in planktonic lines. Convergent evolution affecting dozens of genes indicates that selection acted on a wide variety of traits to improve fitness, causing many adapting lineages to co-occur and persist. This result demonstrates that some environments may expose a large fraction of the genome to selection and select for many adaptations at once, causing enduring diversity.

scholarly journals Bacterial defenses against a natural antibiotic promote collateral resilience to clinical antibiotics

2020 ◽  
Author(s):  
Lucas A. Meirelles ◽  
Elena K. Perry ◽  
Megan Bergkessel ◽  
Dianne K. Newman
Keyword(s):  
Antibiotic Resistance ◽  
Opportunistic Pathogen ◽  
Antimicrobial Treatment ◽  
Bacterial Survival ◽  
Human Pathogens ◽  
Opportunistic Pathogens ◽  
Chronic Infections ◽  
Antibiotic Resistant ◽  
Lung Infections ◽  
Environmental Microbes

SummaryAs antibiotic-resistant infections become increasingly prevalent worldwide, understanding the factors that lead to antimicrobial treatment failure is essential to optimizing the use of existing drugs. Opportunistic human pathogens in particular typically exhibit high levels of intrinsic antibiotic resistance and tolerance1, leading to chronic infections that can be nearly impossible to eradicate2. We asked whether the recalcitrance of these organisms to antibiotic treatment could be driven in part by their evolutionary history as environmental microbes, which frequently produce or encounter natural antibiotics3,4. Using the opportunistic pathogen Pseudomonas aeruginosa as a model, we demonstrate that the self-produced natural antibiotic pyocyanin (PYO) activates bacterial defenses that confer collateral tolerance to certain synthetic antibiotics, including in a clinically-relevant growth medium. Non-PYO-producing opportunistic pathogens isolated from lung infections similarly display increased antibiotic tolerance when they are co-cultured with PYO-producing P. aeruginosa. Furthermore, we show that beyond promoting bacterial survival in the presence of antibiotics, PYO can increase the apparent rate of mutation to antibiotic resistance by up to two orders of magnitude. Our work thus suggests that bacterial production of natural antibiotics in infections could play an important role in modulating not only the immediate efficacy of clinical antibiotics, but also the rate at which antibiotic resistance arises in multispecies bacterial communities.

scholarly journals The saga of scrub typhus with a note on the outbreaks in Mizoram

2018 ◽  
Vol 18 (2) ◽  
pp. 50-57
Author(s):  
K. Lalchhandama
Keyword(s):  
Infectious Disease ◽  
Opportunistic Infection ◽  
Scrub Typhus ◽  
Emerging Infectious Disease ◽  
Human Infection ◽  
Bacterial Disease ◽  
Orientia Tsutsugamushi ◽  
Obligate Parasites ◽  
Serious Disease ◽  
Collective Information

Scrub typhus is one the most important re-emerging infectious disease, and perhaps, the most important bacterial disease. Caused by Orientia tsutsugamushi, it is transmitted through the bite of mites belonging to the genus Leptotrombidium, in which the bacteria are obligate parasites. Though the mites are natural ectoparasites of rodents and other animals, in which there is no disease, opportunistic infection to humans gives rise to a serious disease. Known to Japanese physicians as tsutsugamushi (insect disease), human infection is caused by the larvae of trombiculid mites, the fact established by Mataro Nagayo and co-workers established in 1917. The pathogen was discovered by Naosuke Hayashi in 1920. In Mizoram, the disease has been rampant since 2011. This paper summarises available data on the prevalence of the infection in different districts base on collective information from various sources. Records between 2012 and 2018 show that over a thousand people had been infected and 35 people had died of the disease.

scholarly journals Heterogenous response to R-pyocin killing in populations of Pseudomonas aeruginosa sourced from cystic fibrosis lungs

2020 ◽  
Author(s):  
Madeline Mei ◽  
Jacob Thomas ◽  
Stephen P. Diggle
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Genotypic Diversity ◽  
Opportunistic Pathogen ◽  
Chronic Infections ◽  
Bacterial Populations ◽  
Heterogeneous Populations ◽  
Lung Infections ◽  
The Impact ◽  
Lps Binding

AbstractBacteriocins are proteinaceous antimicrobials produced by bacteria which are active against other strains of the same species. R-type pyocins are phage tail-like bacteriocins produced by Pseudomonas aeruginosa. Due to their anti-pseudomonal activity, R-pyocins have potential as therapeutics in infection. P. aeruginosa is a Gram-negative opportunistic pathogen and is particularly problematic for individuals with cystic fibrosis (CF). P. aeruginosa from CF lung infections develop increasing resistance to antibiotics, making new treatment approaches essential. P. aeruginosa populations become phenotypically and genotypically diverse during infection, however little is known of the efficacy of R-pyocins against heterogeneous populations. R-pyocins vary by subtype (R1-R5), distinguished by binding to different residues on the lipopolysaccharide (LPS). Each type varies in killing spectrum, and each strain produces only one R-type. To evaluate the prevalence of different R-types, we screened P. aeruginosa strains from the International Pseudomonas Consortium Database (IPCD) and from our biobank of CF strains. We found that (i) R1-types were the most prevalent R-type among strains from respiratory sources and (ii) isolates collected from the same patient have the same R-type. We then assessed the impact of diversity on R-pyocin susceptibility and found a heterogenous response to R-pyocins within populations, likely due to differences in the LPS core. Our work reveals that heterogeneous populations of microbes exhibit variable susceptibility to R-pyocins and highlights that there is likely heterogeneity in response to other types of LPS-binding antimicrobials, including phage.ImportanceR-pyocins have potential as alternative therapeutics against Pseudomonas aeruginosa in chronic infection, however little is known about the efficacy of R-pyocins in heterogeneous bacterial populations. P. aeruginosa is known to become resistant to multiple antibiotics, as well as evolve phenotypic and genotypic diversity over time; thus it is particularly difficult to eradicate in chronic cystic fibrosis (CF) lung infections. In this study, we found that P. aeruginosa populations from CF lungs maintain the same R-pyocin genotype but exhibit heterogeneity in susceptibility to R-pyocins from other strains. Our findings suggest there is likely heterogeneity in response to other types of LPS-binding antimicrobials, such as phage, highlighting the necessity of further studying the potential of LPS-binding antimicrobial particles as alternative therapies in chronic infections.

scholarly journals Genome-wide identification of genetic requirements ofPseudomonas aeruginosaPAO1 for rat cardiomyocyte (H9C2) infection by insertion sequencing

2021 ◽  
Author(s):  
Jothi Ranjani ◽  
Ramamoorthy Sivakumar ◽  
Paramasamy Gunasekaran ◽  
Jeyaprakash Rajendhran
Keyword(s):  
Host Cell ◽  
Drug Targets ◽  
Infectious Agent ◽  
Cell Lysis ◽  
Growth Media ◽  
List Type ◽  
H9c2 Cells ◽  
Secretion Systems ◽  
Chronic Infections ◽  
Adhesion And Invasion

AbstractPseudomonas aeruginosais the major infectious agent among Gram-negative bacteria which causes both acute and chronic infections without any tissue specificity. Infections due toP. aeruginosaare hard to treat, as it entails various strategies like virulence factors synthesis, drug efflux systems & resistance and protein secretion systems during pathogenesis. Despite extensive research inPseudomonaspathogenesis, novel drug targets and potential therapeutic strategies are inevitable. In this study, we investigated the genetic requirements ofP.aeruginosaPAO1 for rat cardiomyocyte (H9C2) infection by insertion sequencing (INSeq). A mutant library comprising ~70,000 mutants of PAO1 was generated and the differentiated form of H9C2 cells (d-H9C2) was infected with the library. The infected d-H9C2 cells were maintained with antibiotic-protection and without any antibiotics in the growth media for 24 h. Subsequently, DNA library for INSeq was prepared, sequenced and fitness analysis was performed. A-One hundred and thirteen mutants were negatively selected in the infection condition with antibiotic-protection, whereas 143 mutants were negatively selected in antibiotic-free condition. Surprisingly, a higher number of mutants showed enriched fitness than the mutants of reduced fitness during the infection. We demonstrated that the genes associated with flagella and T3SS are important for adhesion and invasion of cardiomyocytes, while pili and proteases are conditionally essential during host cell lysis.Take away✓Fitness ofP.aeruginosamutants were analyzed during cardiomyocyte infection✓Genes involve amino acid transport & metabolism and signal transduction are important during intracellular lifestyle✓OMVs play a crucial role during infection and pathogenesis✓Flagella and T3SS are conditionally essential for adhesion and invasion, whereas pili and proteases are conditionally essential during host cell lysis

Abstract P190: Triggering of Coronary Heart Disease by Infection Type: The Atherosclerosis Risk in Communities Study

Circulation ◽  
2018 ◽  
Vol 137 (suppl_1) ◽  
Author(s):  
Logan Cowan ◽  
Pamela Lutsey ◽  
Jim Pankow ◽  
Kunihiro Matsushita ◽  
Junichi Ishigami ◽  
...  
Keyword(s):  
Coronary Heart Disease ◽  
Heart Disease ◽  
Infection Type ◽  
Bloodstream Infections ◽  
Infection Frequency ◽  
Acute Infections ◽  
Chd Risk ◽  
Increased Risk ◽  
Infection Types ◽  
Tract Infections

Introduction: Acute infections are known triggers of coronary heart disease (CHD). It is unclear how the strength of the association varies by infection type. Hypothesis: We hypothesized that all acute infections increase CHD risk but the level of increased risk varies by infection type. Methods: Incident CHD (myocardial infarction and fatal CHD) cases were identified and adjudicated in the ARIC cohort. ARIC participants were linked to Medicare claims data. We used ICD-9 codes to identify 4 infection types based on infection frequency: cellulitis, pneumonia, urinary tract infections (UTI), and bloodstream infections. We used a case-crossover design and conditional logistic regression to compare infections among CHD cases 90 days before the event with two corresponding control periods 1 year and 2 years prior. The Wald test was used to assess differences between infection types. Results: A total of 1,312 CHD cases were identified. Among cases, 43 had cellulitis, 102 had pneumonia, 116 had a UTI, and 28 had a bloodstream infection within 90 days of the CHD event. All infection types were associated with higher CHD risk within 90 days of the infection; (odds ratios and 95% Cis) (cellulitis = 1.41 (0.93, 2.15), pneumonia = 5.60 (3.72, 8.43), UTI = 2.62 (1.92, 3.57), bloodstream infections = 4.77 (2.34, 9.71)) although cellulitis was not statistically significant (Figure). The association between infection and CHD was significantly stronger for pneumonia, UTI, and bloodstream infections compared to cellulitis (p<0.05). Pneumonia and bloodstream infections were stronger CHD triggers compared to UTI but only pneumonia reached statistical significance (p<0.05). Conclusions: Patients with pneumonia or bloodstream infections may be at particularly elevated CHD risk. Clinical trials of CHD preventive therapies during and immediately following infection to reduce the otherwise elevated CHD risk are needed. Healthcare providers should consider CHD risk during and immediately after infection and optimize preventive therapies.

Case 43

2020 ◽  
pp. 293-300
Author(s):  
Lucinda Barrett ◽  
Bridget Atkins
Keyword(s):  
Quality Of Life ◽  
Surgical Management ◽  
Chronic Infections ◽  
Joint Replacements ◽  
Preventative Measures ◽  
Acute Infections ◽  
Primary Procedure ◽  
Hip Replacements ◽  
Rich Countries

The number of joint replacements performed in resource-rich countries has increased significantly in the last few decades and has allowed a significant improvement in the quality of life for many patients. Despite preventative measures, a small fraction (around 1% for hip replacements) will become infected. These can present as acute or chronic infections. They can also occur at any time after the primary procedure. Late acute infections are usually via the haematogenous route and often present to the acute medical take or via infection services. A prompt, appropriate medical and surgical management strategy is important.

scholarly journals Protein A-Mediated Multicellular Behavior in Staphylococcus aureus

2008 ◽  
Vol 191 (3) ◽  
pp. 832-843 ◽  
Author(s):  
Nekane Merino ◽  
Alejandro Toledo-Arana ◽  
Marta Vergara-Irigaray ◽  
Jaione Valle ◽  
Cristina Solano ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Biofilm Formation ◽  
Protein A ◽  
Surface Proteins ◽  
Growth Media ◽  
Dependent Manner ◽  
Chronic Infections ◽  
The Matrix ◽  
Implanted Medical Devices ◽  
Biofilm Development

ABSTRACT The capacity of Staphylococcus aureus to form biofilms on host tissues and implanted medical devices is one of the major virulence traits underlying persistent and chronic infections. The matrix in which S. aureus cells are encased in a biofilm often consists of the polysaccharide intercellular adhesin (PIA) or poly-N-acetyl glucosamine (PNAG). However, surface proteins capable of promoting biofilm development in the absence of PIA/PNAG exopolysaccharide have been described. Here, we used two-dimensional nano-liquid chromatography and mass spectrometry to investigate the composition of a proteinaceous biofilm matrix and identified protein A (spa) as an essential component of the biofilm; protein A induced bacterial aggregation in liquid medium and biofilm formation under standing and flow conditions. Exogenous addition of synthetic protein A or supernatants containing secreted protein A to growth media induced biofilm development, indicating that protein A can promote biofilm development without being covalently anchored to the cell wall. Protein A-mediated biofilm formation was completely inhibited in a dose-dependent manner by addition of serum, purified immunoglobulin G, or anti-protein A-specific antibodies. A murine model of subcutaneous catheter infection unveiled a significant role for protein A in the development of biofilm-associated infections, as the amount of protein A-deficient bacteria recovered from the catheter was significantly lower than that of wild-type bacteria when both strains were used to coinfect the implanted medical device. Our results suggest a novel role for protein A complementary to its known capacity to interact with multiple immunologically important eukaryotic receptors.

scholarly journals Overproduction of the AlgT Sigma Factor Is Lethal to Mucoid Pseudomonas aeruginosa

2020 ◽  
Vol 202 (20) ◽  
Author(s):  
Ashley R. Cross ◽  
Vishnu Raghuram ◽  
Zihuan Wang ◽  
Debayan Dey ◽  
Joanna B. Goldberg
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Sigma Factor ◽  
Continuous Production ◽  
Common Mutation ◽  
Wild Type ◽  
Chronic Infections ◽  
Truncated Form ◽  
Content Type ◽  
Lung Infections

ABSTRACT Pseudomonas aeruginosa isolates from chronic lung infections often overproduce alginate, giving rise to the mucoid phenotype. Isolation of mucoid strains from chronic lung infections correlates with a poor patient outcome. The most common mutation that causes the mucoid phenotype is called mucA22 and results in a truncated form of the anti-sigma factor MucA that is continuously subjected to proteolysis. When a functional MucA is absent, the cognate sigma factor, AlgT, is no longer sequestered and continuously transcribes the alginate biosynthesis operon, leading to alginate overproduction. In this work, we report that in the absence of wild-type MucA, providing exogenous AlgT is toxic. This is intriguing, since mucoid strains endogenously possess high levels of AlgT. Furthermore, we show that suppressors of toxic AlgT production have mutations in mucP, a protease involved in MucA degradation, and provide the first atomistic model of MucP. Based on our findings, we speculate that mutations in mucP stabilize the truncated form of MucA22, rendering it functional and therefore able to reduce toxicity by properly sequestering AlgT. IMPORTANCE Pseudomonas aeruginosa is an opportunistic bacterial pathogen capable of causing chronic lung infections. Phenotypes important for the long-term persistence and adaption to this unique lung ecosystem are largely regulated by the AlgT sigma factor. Chronic infection isolates often contain mutations in the anti-sigma factor mucA, resulting in uncontrolled AlgT and continuous production of alginate in addition to the expression of ∼300 additional genes. Here, we report that in the absence of wild-type MucA, AlgT overproduction is lethal and that suppressors of toxic AlgT production have mutations in the MucA protease, MucP. Since AlgT contributes to the establishment of chronic infections, understanding how AlgT is regulated will provide vital information on how P. aeruginosa is capable of causing long-term infections.

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