scholarly journals Exogenous alginate protects Staphylococcus aureus from killing by Pseudomonas aeruginosa

2019 ◽  
Author(s):  
Courtney E. Price ◽  
Dustin G. Brown ◽  
Dominique H. Limoli ◽  
Vanessa V. Phelan ◽  
George A. O’Toole
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Physical Space ◽  
Late Time ◽  
Alginate Production ◽  
Nutritional Conditions ◽  
Culture Models ◽  
The Impact

ABSTRACTCystic fibrosis (CF) patients chronically infected with both Pseudomonas aeruginosa and Staphylococcus aureus have worse health outcomes than patients who are mono-infected with either P. aeruginosa or S. aureus. We showed previously that mucoid strains of P. aeruginosa can co-exist with S. aureus in vitro due to transcriptional downregulation of several toxic exoproducts typically produced by P. aeruginosa, including siderophores, rhamnolipids, and HQNO (2-heptyl-4-hydroxyquinoline N-oxide). Here we demonstrate that exogenous alginate protects S. aureus from P. aeruginosa in both planktonic and biofilm co-culture models under a variety of nutritional conditions. S. aureus protection in the presence of exogenous alginate is due to transcriptional downregulation of pvdA, a gene required for the production of the iron scavenging siderophore pyoverdine, as well as down-regulation of the PQS (Pseudomonas quinolone signal; 2-heptyl-3,4-dihydroxyquinoline) quorum sensing system. The impact of exogenous alginate is independent of endogenous alginate production. We further demonstrate that co-culture of mucoid P. aeruginosa with non-mucoid P. aeruginosa can mitigate the killing of S. aureus by the non-mucoid strain of P. aeruginosa, indicating that the mechanism we describe here may function in vivo in the context of mixed infections. Finally, we investigated a panel of mucoid clinical isolates that retain the ability kill S. aureus at late time points, and show that each strain has a unique expression profile, indicating that mucoid isolates can overcome the effects of mucoidy in a strain-specific manner.IMPORTANCECF patients are chronically infected by polymicrobial communities of microorganisms. The two dominant bacterial pathogens that infect CF patient lungs are P. aeruginosa and S. aureus, with ∼30% of patients co-infected by both species. Patients infected with both P. aeruginosa and S. aureus have worse outcomes than mono-infected patients, and both species persist within the same physical space in the lungs of CF patients. A variety of host and environmental factors have been demonstrated to promote P. aeruginosa-S. aureus co-existence, despite evidence that P. aeruginosa kills S. aureus when these organisms are co-cultured in vitro. Thus, a better understanding of P. aeruginosa-S. aureus interactions, particularly mechanisms by which these microorganisms are able to co-exist in proximal physical space, will lead to better informed treatments for chronic polymicrobial infections.

scholarly journals Exogenous Alginate Protects Staphylococcus aureus from Killing by Pseudomonas aeruginosa

2019 ◽  
Vol 202 (8) ◽  
Author(s):  
Courtney E. Price ◽  
Dustin G. Brown ◽  
Dominique H. Limoli ◽  
Vanessa V. Phelan ◽  
George A. O’Toole
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Physical Space ◽  
Late Time ◽  
Protective Effects ◽  
Content Type ◽  
Alginate Production ◽  
The Impact

ABSTRACT Cystic fibrosis (CF) patients chronically infected with both Pseudomonas aeruginosa and Staphylococcus aureus have worse health outcomes than patients who are monoinfected with either P. aeruginosa or S. aureus. We showed previously that mucoid strains of P. aeruginosa can coexist with S. aureus in vitro due to the transcriptional downregulation of several toxic exoproducts typically produced by P. aeruginosa, including siderophores, rhamnolipids, and HQNO (2-heptyl-4-hydroxyquinoline N-oxide). Here, we demonstrate that exogenous alginate protects S. aureus from P. aeruginosa in both planktonic and biofilm coculture models under a variety of nutritional conditions. S. aureus protection in the presence of exogenous alginate is due to the transcriptional downregulation of pvdA, a gene required for the production of the iron-scavenging siderophore pyoverdine as well as the downregulation of the PQS (Pseudomonas quinolone signal) (2-heptyl-3,4-dihydroxyquinoline) quorum sensing system. The impact of exogenous alginate is independent of endogenous alginate production. We further demonstrate that coculture of mucoid P. aeruginosa with nonmucoid P. aeruginosa strains can mitigate the killing of S. aureus by the nonmucoid strain of P. aeruginosa, indicating that the mechanism that we describe here may function in vivo in the context of mixed infections. Finally, we investigated a panel of mucoid clinical isolates that retain the ability to kill S. aureus at late time points and show that each strain has a unique expression profile, indicating that mucoid isolates can overcome the S. aureus-protective effects of mucoidy in a strain-specific manner. IMPORTANCE CF patients are chronically infected by polymicrobial communities. The two dominant bacterial pathogens that infect the lungs of CF patients are P. aeruginosa and S. aureus, with ∼30% of patients coinfected by both species. Such coinfected individuals have worse outcomes than monoinfected patients, and both species persist within the same physical space. A variety of host and environmental factors have been demonstrated to promote P. aeruginosa-S. aureus coexistence, despite evidence that P. aeruginosa kills S. aureus when these organisms are cocultured in vitro. Thus, a better understanding of P. aeruginosa-S. aureus interactions, particularly mechanisms by which these microorganisms are able to coexist in proximal physical space, will lead to better-informed treatments for chronic polymicrobial infections.

scholarly journals Staphylococcus aureus Serves as an Iron Source for Pseudomonas aeruginosa during In Vivo Coculture

2005 ◽  
Vol 187 (2) ◽  
pp. 554-566 ◽  
Author(s):  
Lauren M. Mashburn ◽  
Amy M. Jett ◽  
Darrin R. Akins ◽  
Marvin Whiteley
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Pathogenic Bacteria ◽  
Iron Acquisition ◽  
Low Oxygen ◽  
Dialysis Membrane ◽  
Opportunistic Human Pathogen ◽  
The Impact

ABSTRACT Pseudomonas aeruginosa is a gram-negative opportunistic human pathogen often infecting the lungs of individuals with the heritable disease cystic fibrosis and the peritoneum of individuals undergoing continuous ambulatory peritoneal dialysis. Often these infections are not caused by colonization with P. aeruginosa alone but instead by a consortium of pathogenic bacteria. Little is known about growth and persistence of P. aeruginosa in vivo, and less is known about the impact of coinfecting bacteria on P. aeruginosa pathogenesis and physiology. In this study, a rat dialysis membrane peritoneal model was used to evaluate the in vivo transcriptome of P. aeruginosa in monoculture and in coculture with Staphylococcus aureus. Monoculture results indicate that approximately 5% of all P. aeruginosa genes are differentially regulated during growth in vivo compared to in vitro controls. Included in this analysis are genes important for iron acquisition and growth in low-oxygen environments. The presence of S. aureus caused decreased transcription of P. aeruginosa iron-regulated genes during in vivo coculture, indicating that the presence of S. aureus increases usable iron for P. aeruginosa in this environment. We propose a model where P. aeruginosa lyses S. aureus and uses released iron for growth in low-iron environments.

Favorable effects in vitro and in vivo of two clinical isolates of Pseudomonas aeruginosa on nutritionally deficient Staphylococcus aureus strains

1973 ◽  
Vol 19 (8) ◽  
pp. 973-981 ◽  
Author(s):  
T. Gadbois ◽  
J. De Repentigny ◽  
L. G. Mathieu
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Peritoneal Cavity ◽  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Mixed Cultures ◽  
Rabbit Skin ◽  
Metabolic Activities

We have studied aspects of interbacterial ecology with nutritionally dependent Staphylococcus aureus strains; they were grown in association with Pseudomonas aeruginosa in systems of mixed cultures and infections in vitro in a semisynthetic medium and in vivo in mouse peritoneal cavity and rabbit skin. In mixed cultures and in P. aeruginosa culture filtrates, thymine and tryptophan deficiencies in staphylococci were partly overcome. This is probably because P. aeruginosa supplied the essential metabolites required to ensure growth; however, other metabolic activities could also be involved. Other experiments showed that the sensitivity of thymineless staphylococci to nucleoside inhibitions was alleviated. In mixed infections with P. aeruginosa, the S. aureus thymineless strain has shown a greater ability to survive in the peritoneal cavity of mice than when injected alone, even when one species was injected after the other with different doses of bacteria. The examination of the liquid from the peritoneal cavity of infected mice by fluorescence microscopy after fluorochroming with acridine orange or auramine O has revealed that Pseudomonas endotoxin seems to damage leucocytes and consequently reduces the phagocytosis of Staphylococcus cells.Necrosis in rabbit skin was mainly due to S. aureus when both species were injected together intradermally; the thymineless strain was less harmful than the parent strain.It seems that survival and even growth of nutritionally dependent strains of a bacterial species can be favored by the metabolic activities of another species in mixed cultures and infections, in this instance S. aureus by P. aeruginosa. This phenomenon among others could be a determinant of bacterial pathogenicity for nutritionally dependent pathogenic bacteria; thus associated organisms could determine the effective pathogenicity of nutritionally dependent bacteria by contributing essential nutrilites at the site where infection is initiated.

scholarly journals The Impacts of msaABCR on sarA-Associated Phenotypes Are Different in Divergent Clinical Isolates of Staphylococcus aureus

2019 ◽  
Vol 88 (2) ◽  
Author(s):  
Joseph S. Rom ◽  
Aura M. Ramirez ◽  
Karen E. Beenken ◽  
Gyan S. Sahukhal ◽  
Mohamed O. Elasri ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Biofilm Formation ◽  
Clinical Isolates ◽  
Protease Production ◽  
Relative Impact ◽  
Extracellular Proteases ◽  
Content Type ◽  
The Impact

ABSTRACT The staphylococcal accessory regulator (sarA) plays an important role in Staphylococcus aureus infections, including osteomyelitis, and the msaABCR operon has been implicated as an important factor in modulating expression of sarA. Thus, we investigated the contribution of msaABCR to sarA-associated phenotypes in the S. aureus clinical isolates LAC and UAMS-1. Mutation of msaABCR resulted in reduced production of SarA and a reduced capacity to form a biofilm in both strains. Biofilm formation was enhanced in a LAC msa mutant by restoring the production of SarA, but this was not true in a UAMS-1 msa mutant. Similarly, extracellular protease production was increased in a LAC msa mutant but not a UAMS-1 msa mutant. This difference was reflected in the accumulation and distribution of secreted virulence factors and in the impact of extracellular proteases on biofilm formation in a LAC msa mutant. Most importantly, it was reflected in the relative impact of mutating msa as assessed in a murine osteomyelitis model, which had a significant impact in LAC but not in UAMS-1. In contrast, mutation of sarA had a greater impact on all of these in vitro and in vivo phenotypes than mutation of msaABCR, and it did so in both LAC and UAMS-1. These results suggest that, at least in osteomyelitis, it would be therapeutically preferable to target sarA rather than msaABCR to achieve the desired clinical result, particularly in the context of divergent clinical isolates of S. aureus.

scholarly journals Antimicrobial Properties of Mesenchymal Stem Cells: Therapeutic Potential for Cystic Fibrosis Infection, and Treatment

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Morgan T. Sutton ◽  
David Fletcher ◽  
Santosh K. Ghosh ◽  
Aaron Weinberg ◽  
Rolf van Heeckeren ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Bacterial Growth ◽  
Therapeutic Potential ◽  
Bioactive Molecules ◽  
Human Mscs ◽  
Antimicrobial Effectiveness

Cystic fibrosis (CF) is a genetic disease in which the battle between pulmonary infection and inflammation becomes the major cause of morbidity and mortality. We have previously shown that human MSCs (hMSCs) decrease inflammation and infection in thein vivomurine model of CF. The studies in this paper focus on the specificity of the hMSC antimicrobial effectiveness usingPseudomonas aeruginosa(gram negative bacteria) andStaphylococcus aureus(gram positive bacteria). Our studies show that hMSCs secrete bioactive molecules which are antimicrobialin vitroagainstPseudomonas aeruginosa, Staphylococcus aureus,andStreptococcus pneumonia, impacting the rate of bacterial growth and transition into colony forming units regardless of the pathogen. Further, we show that the hMSCs have the capacity to enhance antibiotic sensitivity, improving the capacity to kill bacteria. We present data which suggests that the antimicrobial effectiveness is associated with the capacity to slow bacterial growth and the ability of the hMSCs to secrete the antimicrobial peptide LL-37. Lastly, our studies demonstrate that the tissue origin of the hMSCs (bone marrow or adipose tissue derived), the presence of functional cystic fibrosis transmembrane conductance regulator (CFTR: human,Cftr: mouse) activity, and response to effector cytokines can impact both hMSC phenotype and antimicrobial potency and efficacy. These studies demonstrate, the unique capacity of the hMSCs to manage different pathogens and the significance of their phenotype in both the antimicrobial and antibiotic enhancing activities.

scholarly journals The Autofluorescence Patterns of Acanthamoeba castellanii, Pseudomonas aeruginosa and Staphylococcus aureus: Effects of Antibiotics and Tetracaine

Pathogens ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 894
Author(s):  
Hari Peguda ◽  
Saabah Mahbub ◽  
Tashi Sherpa ◽  
Dinesh Subedi ◽  
Abbas Habibalahi ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Vision Loss ◽  
Delayed Diagnosis ◽  
Acanthamoeba Castellanii ◽  
Acanthamoeba Keratitis ◽  
Fluorescence Pattern ◽  
And Staphylococcus Aureus

Acanthamoeba Keratitis (AK) can lead to substantial vision loss and morbidity among contact lens wearers. Misdiagnosis or delayed diagnosis is a major factor contributing to poor outcomes of AK. This study aimed to assess the effect of two antibiotics and one anaesthetic drug used in the diagnosis and nonspecific management of keratitis on the autofluorescence patterns of Acanthamoeba and two common bacteria that may also cause keratitis. Acanthamoeba castellanii ATCC 30868, Pseudomonas aeruginosa ATCC 9027, and Staphylococcus aureus ATCC 6538 were grown then diluted in either PBS (bacteria) or ¼ strength Ringer’s solution (Acanthamoeba) to give final concentrations of 0.1 OD at 660 nm or 104 cells/mL. Cells were then treated with ciprofloxacin, tetracycline, tetracaine, or no treatment (naïve). Excitation–emission matrices (EEMs) were collected for each sample with excitation at 270–500 nm with increments in 5 nm steps and emission at 280–700 nm at 2 nm steps using a Fluoromax-4 spectrometer. The data were analysed using MATLAB software to produce smoothed color-coded images of the samples tested. Acanthamoeba exhibited a distinctive fluorescence pattern compared to bacteria. The addition of antibiotics and anaesthetic had variable effects on autofluorescence. Tetracaine altered the fluorescence of all three microorganisms, whereas tetracycline did not show any effect on the fluorescence. Ciprofloxacin produced changes to the fluorescence pattern for the bacteria, but not Acanthamoeba. Fluorescence spectroscopy was able to differentiate Acanthamoeba from P. aeruginosa and S. aureus in vitro. There is a need for further assessment of the fluorescence pattern for different strains of Acanthamoeba and bacteria. Additionally, analysis of the effects of anti-amoebic drugs on the fluorescence pattern of Acanthamoeba and bacteria would be prudent before in vivo testing of the fluorescence diagnostic approach in the animal models.

scholarly journals Adaptation of Staphylococcus aureus in a Medium Mimicking a Diabetic Foot Environment

Toxins ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 230
Author(s):  
Cassandra Pouget ◽  
Claude-Alexandre Gustave ◽  
Christelle Ngba-Essebe ◽  
Frédéric Laurent ◽  
Emmanuel Lemichez ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Diabetic Foot ◽  
In Vitro Model ◽  
Virulence Genes ◽  
Chronic Wounds ◽  
Ring Test ◽  
Vitro Model ◽  
The Impact

Staphylococcus aureus is the most prevalent pathogen isolated from diabetic foot infections (DFIs). The purpose of this study was to evaluate its behavior in an in vitro model mimicking the conditions encountered in DFI. Four clinical S. aureus strains were cultivated for 16 weeks in a specific environment based on the wound-like medium biofilm model. The adaptation of isolates was evaluated as follows: by Caenorhabditis elegans model (to evaluate virulence); by quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) (to evaluate expression of the main virulence genes); and by Biofilm Ring test® (to assess the biofilm formation). After 16 weeks, the four S. aureus had adapted their metabolism, with the development of small colony variants and the loss of b-hemolysin expression. The in vivo nematode model suggested a decrease of virulence, confirmed by qRT-PCRs, showing a significant decrease of expression of the main staphylococcal virulence genes tested, notably the toxin-encoding genes. An increased expression of genes involved in adhesion and biofilm was noted. Our data based on an in vitro model confirm the impact of environment on the adaptation switch of S. aureus to prolonged stress environmental conditions. These results contribute to explore and characterize the virulence of S. aureus in chronic wounds.

scholarly journals ДОКЛІНІЧНЕ ДОСЛІДЖЕННЯ НАНОЧАСТИНОК ФЕРУМУ

2021 ◽  
pp. 17-24
Author(s):  
Y. S. Stravskyy ◽  
L. Ya. Fedoniuk ◽  
O. M. Yarema ◽  
E. І. Skyba ◽  
L. S. Reznichenko
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Candida Albicans ◽  
Salmonella Typhimurium ◽  
Proteus Mirabilis ◽  
Shigella Sonnei ◽  
Proteus Vulgaris

Вступ. Доклінічне вивчення лікарських препаратів – невід’ємна частина процесу створення лікарського засобу. Доклінічне дослідження є найбільш тривалим та відповідальним етапом розробки лікарського засобу, який вимагає особливих підходів до планування і забезпечення якості при плануванні вимірювальних експериментів, проведенні випробування та оцінки його результатів. Мета дослідження – визначити біобезпечність, гостру токсичність, протимікробну та фунгіцидну дії наночастинок Феруму. Методи дослідження. Біобезпечність синтезованої субстанції наночастинок у тестах in vitro визначали з використанням показників цитотоксичності, мутагенності, молекулярно-генетичного (показник генотоксичності), фізіологічного (стан мікрофлори шлунково-кишкового тракту людини) та біохімічних (ATФ-aзна і лактатдегідрогеназна активність) маркерів. Протимікробну дію нуль-валентного Феруму (Fe0NP) щодо тест-штамів мікроорганізмів визначали методом серійних розведень у бульйоні відповідно до Методичних вказівок 4.2.1890-04, 2004. Використовували такі тест-штами мікроорганізмів, як Salmonella typhimurium, Shigella sonnei, Staphylococcus aureus, Pseudomonas aeruginosa, Proteus vulgaris, Proteus mirabilis, Candida albicans, із колекції Державного науково-контрольного інституту біотехнології і штамів мікро­організмів. Результати й обговорення. Синтезовані наночастинки є частинками Fe0NP. Взаємодія синтезованих наночастинок Феруму з тестовими еукаріотичними клітинами не призводила до появи первинних ДНК‑ушко­джень порівняно з впливом N-нітрозометилсечовини, яка є відомим генотоксикантом. Синтезовані наночастинки характеризувались як біобезпечні у тестах на мутагенність з використанням поліхроматофільних еритроцитів кісткового мозку тварин. Аналіз показав, що експериментальна субстанція Fe0NP у досліджуваному концентраційному діапазоні проявила помірну протимікробну активність у тестах in vitro відносно як грамнегативних (S. typhimurium, S. sonnei, P. aeruginosa, P. vulgaris, P. mirabilis), так і грампозитивних (S. aureus) мікроорганізмів. Однак гриби Candida albicans виявилися нечутливими до наночастинок Феруму в досліджуваних концентраціях. Висновки. Фізико-хімічна характеристика й оцінка критеріїв біобезпечності в тестах in vitro та in vivo свідчать про те, що синтезованим сферичним наночастинкам нуль-валентного Феруму властивий низький рівень потенційної небезпеки: виявлено відсутність генотоксичної, цитотоксичної, мутагенної дій, негативного впливу на ключові біохімічні параметри і загальний фізіологічний стан живого організму. Це дозволяє рекомендувати синтезовану субстанцію наночастинок Феруму для подальших досліджень з метою їх застосування як потенційної біологічно активної субстанції.

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