Management of the limited number of antimicrobials currently available requires the identification of infections that contain drug-resistant isolates and the discovery of factors that promote the evolution of drug resistance. Here, we report a single fungal infection in which we have identified numerous subpopulations that differ in their alleles of a single gene that impacts drug resistance. The diversity at this locus was markedly greater than the reported heterogeneity of alleles conferring antibiotic resistance in bacterial infections. Analysis of genomes from hundreds of
This content will become publicly available on December 12, 2024
Chronic, highly antibiotic-resistant infections in cystic fibrosis (CF) lungs contribute to increasing morbidity and mortality.
Cystic fibrosis (CF) patients often experience chronic, debilitating lung infections caused by antibiotic-resistant
- Award ID(s):
- 2003721
- NSF-PAR ID:
- 10530827
- Editor(s):
- Van_Tyne, Daria
- Publisher / Repository:
- ASM
- Date Published:
- Journal Name:
- Microbiology Spectrum
- Volume:
- 11
- Issue:
- 6
- ISSN:
- 2165-0497
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Clavispora (Candida )lusitaniae isolates, through individual and pooled isolate sequencing, from a single individual with cystic fibrosis revealed at least 25 nonsynonymous mutations inMRR1 , which encodes a transcription factor capable of inducing fluconazole (FLZ) resistance inCandida species. Isolates with high-activity Mrr1 variants were resistant to FLZ due to elevated expression of theMDR1 -encoded efflux pump. We found that high Mrr1-regulated Mdr1 activity protected against host and bacterial factors, suggesting drug resistance can be selected for indirectly and perhaps explaining the Mrr1 heterogeneity in this individual who had no prior azole exposure. Regional analysis ofC. lusitaniae populations from the upper and lower lobes of the right lung suggested intermingling of subpopulations throughout. Our retrospective characterization of sputum and lung populations by pooled sequencing found that alleles that confer FLZ resistance were a minority in each pool, possibly explaining why they were undetected before unsuccessful FLZ therapy. New susceptibility testing regimes may detect problematical drug-resistant subpopulations in heterogeneous single-species infections. -
Trent, M. Stephen (Ed.)ABSTRACT Bacteria live in spatially organized aggregates during chronic infections, where they adapt to the host environment, evade immune responses, and resist therapeutic interventions. Although it is known that environmental factors such as polymers influence bacterial aggregation, it is not clear how bacterial adaptation during chronic infection impacts the formation and spatial organization of aggregates in the presence of polymers. Here, we show that in an in vitro model of cystic fibrosis (CF) containing the polymers extracellular DNA (eDNA) and mucin, O-specific antigen is a major factor determining the formation of two distinct aggregate assembly types of Pseudomonas aeruginosa due to alterations in cell surface hydrophobicity. Our findings suggest that during chronic infection, the interplay between cell surface properties and polymers in the environment may influence the formation and structure of bacterial aggregates, which would shed new light on the fitness costs and benefits of O-antigen production in environments such as CF lungs. IMPORTANCE During chronic infection, several factors contribute to the biogeography of microbial communities. Heterogeneous populations of Pseudomonas aeruginosa form aggregates in cystic fibrosis airways; however, the impact of this population heterogeneity on spatial organization and aggregate assembly is not well understood. In this study, we found that changes in O-specific antigen determine the spatial organization of P. aeruginosa cells by altering the relative cell surface hydrophobicity. This finding suggests a role for O-antigen in regulating P. aeruginosa aggregate size and shape in cystic fibrosis airways.more » « less
-
more » « less
Introduction Chronic lung infection due to bacterial biofilms is one of the leading causes of mortality in cystic fibrosis (CF) patients. Among many species colonizing the lung airways,
Pseudomonas aeruginosa andStaphylococcus aureus are two virulent pathogens involved in mechanically robust biofilms that are difficult to eradicate using airway clearance techniques like lung lavage. To remove such biological materials, glycoside hydrolase-based compounds are commonly employed for targeting and breaking down the biofilm matrix, and subsequently increasing cell susceptibility to antibiotics.Materials and methods In this study, we evaluate the effects of N-acetyl cysteine (NAC) and Cysteamine (CYST) in disrupting interfacial bacterial films, targeting different components of the extracellular polymeric substances (EPS). We characterize the mechanics and structural integrity of the interfacial bacterial films using pendant drop elastometry and scanning electron microscopy.
Results and discussion Our results show that the film architectures are compromised by treatment with disrupting agents for 6 h, which reduces film elasticity significantly. These effects are profound in the wild type and mucoid
P. aeruginosa , compared toS. aureus . We further assess the effects of competition and cooperation betweenS. aureus andP. aeruginosa on the mechanics of composite interfacial films. Films ofS. aureus and wild-typeP. aeruginosa cocultures lose mechanical strength while those ofS. aureus and mucoidP. aeruginosa exhibit improved storage modulus. Treatment with NAC and CYST reduces the elastic property of both composite films, owing to the drugs’ ability to disintegrate their EPS matrix. Overall, our results provide new insights into methods for assessing the efficacy of mucolytic agents against interfacial biofilms relevant to cystic fibrosis infection. -
more » « less
Abstract Bacterial infections in cystic fibrosis (CF) patients are an emerging health issue and lead to a premature death. CF is a hereditary disease that creates a thick mucus in the lungs that is prone to bacterial biofilm formation, specifically
Pseudomonas aeruginosa biofilms. These biofilms are very difficult to treat because many of them have antibiotic resistance that is worsened by the presence of extracellular DNA (eDNA). eDNA helps to stabilize biofilms and can bind antimicrobial compounds to lessen their effects. The metallo‐antimicrobial peptide Gaduscidin‐1 (Gad‐1) eradicates establishedP. aeruginosa biofilms through a combination of modes of action that includes nuclease activity that can cleave eDNA in biofilms. In addition, Gad‐1 exhibits synergistic activity when used with the antibiotics kanamycin and ciprofloxacin, thus making Gad‐1 a new lead compound for the potential treatment of bacterial biofilms in CF patients. -
Alspaugh, J. Andrew (Ed.)The identification of MRS4 mutations in Clavispora ( Candida ) lusitaniae and Exophiala dermatitidis in individuals with cystic fibrosis (CF) highlights a possible adaptive mechanism for fungi during chronic CF lung infections. The findings of this study suggest that loss of function of the mitochondrial iron transporter Mrs4 can lead to increased activity of iron acquisition mechanisms, which may be advantageous for fungi in iron-restricted environments during chronic infections. This study provides valuable information for researchers working toward a better understanding of the pathogenesis of chronic lung infections and more effective therapies to treat them.more » « less
