scholarly journals Candida guilliermondii Complex Is Characterized by High Antifungal Resistance but Low Mortality in 22 Cases of Candidemia

2017 ◽  
Vol 61 (7) ◽  
Author(s):  
Laura Judith Marcos-Zambrano ◽  
Mireia Puig-Asensio ◽  
Felipe Pérez-García ◽  
Pilar Escribano ◽  
Carlos Sánchez-Carrillo ◽  
...  
Keyword(s):  
Metabolic Activity ◽  
Biofilm Formation ◽  
Galleria Mellonella ◽  
Sensu Stricto ◽  
Candida Guilliermondii ◽  
Molecular Techniques ◽  
Content Type ◽  
Content Model ◽  
Crystal Violet Assay

ABSTRACT The objectives of our study were to describe the characteristics of patients with Candida guilliermondii candidemia and to perform an in-depth microbiological characterization of isolates and compare them with those of patients with C. albicans candidemia. We described the risk factors and outcomes of 22 patients with candidemia caused by the C. guilliermondii complex. Incident isolates were identified using molecular techniques, and susceptibility to fluconazole, anidulafungin, and micafungin was studied. Biofilm formation was measured using the crystal violet assay (biomass production) and the XTT reduction assay (metabolic activity), and virulence was studied using the Galleria mellonella model. Biofilm formation was compared with that observed for C. albicans. The main conditions predisposing to infection were malignancy (68%), immunosuppressive therapy (59%), and neutropenia (18%). Clinical presentation of candidemia was less severe in patients infected by the C. guilliermondii complex than in patients infected by C. albicans, and 30-day mortality was lower in C. guilliermondii patients (13.6% versus 33.9%, respectively; P = 0.049). Isolates were identified as C. guilliermondii sensu stricto (n = 17) and Candida fermentati (n = 5). The isolates produced biofilms with low metabolic activity and moderate biomass. The G. mellonella model showed that C. guilliermondii was less virulent than C. albicans (mean of 6 days versus 1 day of survival, respectively; P < 0.001). Patients with candidemia caused by the C. guilliermondii complex had severe and debilitating underlying conditions. Overall, the isolates showed diminished susceptibility to fluconazole and echinocandins, although poor biofilm formation and the low virulence were associated with a favorable outcome.

scholarly journals Characterization of RelA in Acinetobacter baumannii

2020 ◽  
Vol 202 (12) ◽  
Author(s):  
María Pérez-Varela ◽  
Aimee R. P. Tierney ◽  
Ju-Sim Kim ◽  
Andrés Vázquez-Torres ◽  
Philip Rather
Keyword(s):  
Acinetobacter Baumannii ◽  
Galleria Mellonella ◽  
Multidrug Resistant ◽  
Cell Physiology ◽  
Content Type ◽  
Content Model ◽  
Transposon Insertion ◽  
Downstream Effectors

ABSTRACT In response to nutrient depletion, the RelA and SpoT proteins generate the signaling molecule (p)ppGpp, which then controls a number of downstream effectors to modulate cell physiology. In Acinetobacter baumannii strain AB5075, a relA ortholog (ABUW_3302) was identified by a transposon insertion that conferred an unusual colony phenotype. An in-frame deletion in relA (ΔrelA) failed to produce detectable levels of ppGpp when amino acid starvation was induced with serine hydroxamate. The ΔrelA mutant was blocked from switching from the virulent opaque colony variant (VIR-O) to the avirulent translucent colony variant (AV-T), but the rate of AV-T to VIR-O switching was unchanged. In addition, the ΔrelA mutation resulted in a pronounced hypermotile phenotype on 0.35% agar plates. This hypermotility was dependent on the activation of a LysR regulator ABUW_1132, which was required for expression of AbaR, a LuxR family quorum-sensing regulator. In the ΔrelA mutant, ABUW_1132 was also required for the increased expression of an operon composed of the ABUW_3766-ABUW_3773 genes required for production of the surfactant-like lipopeptide acinetin 505. Additional phenotypes identified in the ΔrelA mutant included (i) cell elongation at high density, (ii) reduced formation of persister cells tolerant to colistin and rifampin, and (iii) decreased virulence in a Galleria mellonella model. IMPORTANCE Acinetobacter baumannii is a pathogen of worldwide importance. Due to the increasing prevalence of antibiotic resistance, these infections are becoming increasingly difficult to treat. New therapies are required to combat multidrug-resistant isolates. The role of RelA in A. baumannii is largely unknown. This study demonstrates that like in other bacteria, RelA controls a variety of functions, including virulence. Strategies to inhibit the activity of RelA and the resulting production of ppGpp could inhibit virulence and may represent a new therapeutic approach.

scholarly journals Novel Cadmium Resistance Determinant in Listeria monocytogenes

2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Cameron Parsons ◽  
Sangmi Lee ◽  
Victor Jayeola ◽  
Sophia Kathariou
Keyword(s):  
Heavy Metals ◽  
Listeria Monocytogenes ◽  
Biofilm Formation ◽  
Galleria Mellonella ◽  
Foodborne Pathogen ◽  
Whole Genome ◽  
Cadmium Resistance ◽  
Content Type ◽  
Content Model ◽  
Tolerance To Cadmium

ABSTRACT Listeria monocytogenes is a foodborne pathogen that can cause severe disease (listeriosis) in susceptible individuals. It is ubiquitous in the environment and often exhibits resistance to heavy metals. One of the determinants that enables Listeria to tolerate exposure to cadmium is the cadAC efflux system, with CadA being a P-type ATPase. Three different cadA genes (designated cadA1 to cadA3) were previously characterized in L. monocytogenes. A novel putative cadmium resistance gene (cadA4) was recently identified through whole-genome sequencing, but experimental confirmation for its involvement in cadmium resistance is lacking. In this study, we characterized cadA4 in L. monocytogenes strain F8027, a cadmium-resistant strain of serotype 4b. By screening a mariner-based transposon library of this strain, we identified a mutant with reduced tolerance to cadmium and that harbored a single transposon insertion in cadA4. The tolerance to cadmium was restored by genetic complementation with the cadmium resistance cassette (cadA4C), and enhanced cadmium tolerance was conferred to two unrelated cadmium-sensitive strains via heterologous complementation with cadA4C. Cadmium exposure induced cadA4 expression, even at noninhibitory levels. Virulence assessments in the Galleria mellonella model suggested that a functional cadA4 suppressed virulence, potentially promoting commensal colonization of the insect larvae. Biofilm assays suggested that cadA4 inactivation reduced biofilm formation. These data not only confirm cadA4 as a novel cadmium resistance determinant in L. monocytogenes but also provide evidence for roles in virulence and biofilm formation. IMPORTANCE Listeria monocytogenes is an intracellular foodborne pathogen causing the disease listeriosis, which is responsible for numerous hospitalizations and deaths every year. Among the adaptations that enable the survival of Listeria in the environment are the abilities to persist in biofilms, grow in the cold, and tolerate toxic compounds, such as heavy metals. Here, we characterized a novel determinant that was recently identified on a larger mobile genetic island through whole-genome sequencing. This gene (cadA4) was found to be responsible for cadmium detoxification and to be a divergent member of the Cad family of cadmium efflux pumps. Virulence assessments in a Galleria mellonella model suggested that cadA4 may suppress virulence. Additionally, cadA4 may be involved in the ability of Listeria to form biofilms. Beyond the role in cadmium detoxification, the involvement of cadA4 in other cellular functions potentially explains its retention and wide distribution in L. monocytogenes.

scholarly journals In VitroAnalyses of the Effects of Heparin and Parabens on Candida albicans Biofilms and Planktonic Cells

2011 ◽  
Vol 56 (1) ◽  
pp. 148-153 ◽  
Author(s):  
Marisa H. Miceli ◽  
Stella M. Bernardo ◽  
T. S. Neil Ku ◽  
Carla Walraven ◽  
Samuel A. Lee
Keyword(s):  
Candida Albicans ◽  
Metabolic Activity ◽  
Biofilm Formation ◽  
High Dose ◽  
Dependent Manner ◽  
Planktonic Cells ◽  
Content Type ◽  
Heparin Sodium ◽  
The Individual

ABSTRACTInfections and thromboses are the most common complications associated with central venous catheters. Suggested strategies for prevention and management of these complications include the use of heparin-coated catheters, heparin locks, and antimicrobial lock therapy. However, the effects of heparin onCandida albicansbiofilms and planktonic cells have not been previously studied. Therefore, we sought to determine thein vitroeffect of a heparin sodium preparation (HP) on biofilms and planktonic cells ofC. albicans. Because HP contains two preservatives, methyl paraben (MP) and propyl paraben (PP), these compounds and heparin sodium without preservatives (Pure-H) were also tested individually. The metabolic activity of the mature biofilm after treatment was assessed using XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction and microscopy. Pure-H, MP, and PP caused up to 75, 85, and 60% reductions of metabolic activity of the mature preformedC. albicansbiofilms, respectively. Maximal efficacy against the mature biofilm was observed with HP (up to 90%) compared to the individual compounds (P< 0.0001). Pure-H, MP, and PP each inhibitedC. albicansbiofilm formation up to 90%. A complete inhibition of biofilm formation was observed with HP at 5,000 U/ml and higher. When tested against planktonic cells, each compound inhibited growth in a dose-dependent manner. These data indicated that HP, MP, PP, and Pure-H havein vitroantifungal activity againstC. albicansmature biofilms, formation of biofilms, and planktonic cells. Investigation of high-dose heparin-based strategies (e.g., heparin locks) in combination with traditional antifungal agents for the treatment and/or prevention ofC. albicansbiofilms is warranted.

scholarly journals A Light-Regulated Type I Pilus Contributes toAcinetobacter baumanniiBiofilm, Motility, and Virulence Functions

2018 ◽  
Vol 86 (9) ◽  
Author(s):  
Cecily R. Wood ◽  
Emily J. Ohneck ◽  
Richard E. Edelmann ◽  
Luis A. Actis
Keyword(s):  
Biofilm Formation ◽  
Galleria Mellonella ◽  
Alveolar Epithelial Cells ◽  
Ecological Niches ◽  
Type I ◽  
Pellicle Formation ◽  
Content Type ◽  
Alveolar Epithelial ◽  
Abiotic Surfaces ◽  
Cells Cultured

ABSTRACTTranscriptional analyses ofAcinetobacter baumanniiATCC 17978 showed that the expression of A1S_2091 was enhanced in cells cultured in darkness at 24°C through a process that depended on the BlsA photoreceptor. Disruption of A1S_2091, a component of the A1S_2088-A1S_2091 polycistronic operon predicted to code for a type I chaperone/usher pilus assembly system, abolished surface motility and pellicle formation but significantly enhanced biofilm formation on plastic by bacteria cultured in darkness. Based on these observations, the A1S_2088-A1S_2091 operon was named thephotoregulatedpilus ABCD (prpABCD) operon, with A1S_2091 coding for the PrpA pilin subunit. Unexpectedly, comparative analyses of ATCC 17978 andprpAisogenic mutant cells cultured at 37°C showed the expression of light-regulated biofilm biogenesis and motility functions under a temperature condition that drastically affects BlsA production and its light-sensing activity. These assays also suggest that ATCC 17978 cells produce alternative light-regulated adhesins and/or pilus systems that enhance bacterial adhesion and biofilm formation at both 24°C and 37°C on plastic as well as on the surface of polarized A549 alveolar epithelial cells, where the formation of bacterial filaments and cell chains was significantly enhanced. The inactivation ofprpAalso resulted in a significant reduction in virulence when tested by using theGalleria mellonellavirulence model. All these observations provide strong evidence showing the capacity ofA. baumanniito sense light and interact with biotic and abiotic surfaces using undetermined alternative sensing and regulatory systems as well as alternative adherence and motility cellular functions that allow this pathogen to persist in different ecological niches.

scholarly journals Characterization of Biofilm Formation and the Role of BCR1 in Clinical Isolates of Candida parapsilosis

2013 ◽  
Vol 13 (4) ◽  
pp. 438-451 ◽  
Author(s):  
Srisuda Pannanusorn ◽  
Bernardo Ramírez-Zavala ◽  
Heinrich Lünsdorf ◽  
Birgitta Agerberth ◽  
Joachim Morschhäuser ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Candida Parapsilosis ◽  
Clinical Isolates ◽  
Wild Type ◽  
Content Type ◽  
Initial Adhesion ◽  
High Level ◽  
Increased Susceptibility

ABSTRACT In Candida parapsilosis , biofilm formation is considered to be a major virulence factor. Previously, we determined the ability of 33 clinical isolates causing bloodstream infection to form biofilms and identified three distinct groups of biofilm-forming strains (negative, low, and high). Here, we establish two different biofilm structures among strains forming large amounts of biofilm in which strains with complex spider-like structures formed robust biofilms on different surface materials with increased resistance to fluconazole. Surprisingly, the transcription factor Bcr1, required for biofilm formation in Candida albicans and C. parapsilosis , has an essential role only in strains with low capacity for biofilm formation. Although BCR1 leads to the formation of more and longer pseudohyphae, it was not required for initial adhesion and formation of mature biofilms in strains with a high level of biofilm formation. Furthermore, an additional phenotype affected by BCR1 was the switch in colony morphology from rough to crepe, but only in strains forming high levels of biofilm. All bcr1 Δ/Δ mutants showed increased proteolytic activity and increased susceptibility to the antimicrobial peptides protamine and RP-1 compared to corresponding wild-type and complemented strains. Taken together, our results demonstrate that biofilm formation in clinical isolates of C. parapsilosis is both dependent and independent of BCR1 , but even in strains which showed a BCR1 -independent biofilm phenotype, BCR1 has alternative physiological functions.

scholarly journals Characterization of Pre-Antibiotic Era Klebsiella pneumoniae Isolates with Respect to Antibiotic/Disinfectant Susceptibility and Virulence in Galleria mellonella

2015 ◽  
Vol 59 (7) ◽  
pp. 3966-3972 ◽  
Author(s):  
Matthew E. Wand ◽  
Kate S. Baker ◽  
Gabriel Benthall ◽  
Hannah McGregor ◽  
James W. I. McCowen ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Susceptibility Testing ◽  
Galleria Mellonella ◽  
Significant Proportion ◽  
Minimal Bactericidal Concentration ◽  
Bacterial Isolates ◽  
Content Type ◽  
The Mean ◽  
Two Populations

ABSTRACTThe EGD Murray collection consists of approximately 500 clinical bacterial isolates, mainlyEnterobacteriaceae, isolated from around the world between 1917 and 1949. A number of these “Murray” isolates have subsequently been identified asKlebsiella pneumoniae. Antimicrobial susceptibility testing of these isolates showed that over 30% were resistant to penicillins due to the presence of diverseblaSHVβ-lactamase genes. Analysis of susceptibility to skin antiseptics and triclosan showed that while the Murray isolates displayed a range of MIC/minimal bactericidal concentration (MBC) values, the mean MIC value was lower than that for more modernK. pneumoniaeisolates tested. All Murray isolates contained the cation efflux genecepA, which is involved in disinfectant resistance, but those that were more susceptible to chlorhexidine were found to have a 9- or 18-bp insertion in this gene. Susceptibility to other disinfectants, e.g., H2O2, in the Murray isolates was comparable to that in modernK. pneumoniaeisolates. The Murray isolates were also less virulent inGalleriaand had a different complement of putative virulence factors than the modern isolates, with the exception of an isolate related to the modern lineage CC23. More of the modern isolates (41% compared to 8%) are classified as good/very good biofilm formers, but there was overlap in the two populations. This study demonstrated that a significant proportion of the MurrayKlebsiellaisolates were resistant to penicillins before their routine use. This collection of pre-antibiotic era isolates may provide significant insights into adaptation inK. pneumoniaein relation to biocide susceptibility.

scholarly journals Attenuated Virulence and Biofilm Formation in Staphylococcus aureus following Sublethal Exposure to Triclosan

2012 ◽  
Vol 56 (6) ◽  
pp. 3092-3100 ◽  
Author(s):  
Joe Latimer ◽  
Sarah Forbes ◽  
Andrew J. McBain
Keyword(s):  
Staphylococcus Aureus ◽  
Growth Rate ◽  
Growth Rates ◽  
Biofilm Formation ◽  
Galleria Mellonella ◽  
Concentration Gradients ◽  
Content Type ◽  
Small Colony Variant ◽  
Small Colony ◽  
Repeated Passage

ABSTRACTSubeffective exposure ofStaphylococcus aureusto the biocide triclosan can reportedly induce a small-colony variant (SCV) phenotype.S. aureusSCVs are characterized by low growth rates, reduced pigmentation, and lowered antimicrobial susceptibility. While they may exhibit enhanced intracellular survival, there are conflicting reports regarding their pathogenicity. The current study reports the characteristics of an SCV-like strain ofS. aureuscreated by repeated passage on sublethal triclosan concentrations.S. aureusATCC 6538 (the passage 0 [P0] strain) was serially exposed 10 times to concentration gradients of triclosan to generate strain P10. This strain was then further passaged 10 times on triclosan-free medium (designated strain ×10). The MICs and minimum bactericidal concentrations of triclosan for P0, P10, and ×10 were determined, and growth rates in biofilm and planktonic cultures were measured. Hemolysin, DNase, and coagulase activities were measured, and virulence was determined using aGalleria mellonellapathogenicity model. Strain P10 exhibited decreased susceptibility to triclosan and characteristics of an SCV phenotype, including a considerably reduced growth rate and the formation of pinpoint colonies. However, this strain also had delayed coagulase production, had impaired hemolysis (P< 0.01), was defective in biofilm formation and DNase activity, and displayed significantly attenuated virulence. Colony size, hemolysis, coagulase activity, and virulence were only partially restored in strain ×10, whereas the planktonic growth rate was fully restored. However, ×10 was at least as defective in biofilm formation and DNase production as P10. These data suggest that although repeated exposure to triclosan may result in an SCV-like phenotype, this is not necessarily associated with increased virulence and adapted bacteria may exhibit other functional deficiencies.

scholarly journals Effects of Norspermidine on Dual‐Species Biofilms Composed of Streptococcus mutans and Streptococcus sanguinis

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Yan Sun ◽  
Yihuai Pan ◽  
Yu Sun ◽  
Mingyun Li ◽  
Shengbin Huang ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Metabolic Activity ◽  
Biofilm Formation ◽  
Acid Production ◽  
Single Species ◽  
Extracellular Polysaccharides ◽  
Streptococcus Sanguinis ◽  
Crystal Violet Assay ◽  
Sem Imaging

The present study aimed at investigating the influence of norspermidine on the formation of dual-species biofilms composed of Streptococcus mutans (S. mutans) and Streptococcus sanguinis (S. sanguinis). Crystal violet assay was conducted to assess the formation of single-species biofilms of S. mutans and S. sanguinis, and the growth curve was carefully observed to monitor the growth of these two species of bacteria. Fluorescence in situ hybridization (FISH) and MTT array were used to analyze the composition and metabolic activity of the dual-species biofilms, respectively. Extracellular polysaccharides (EPS)/bacteria staining, anthrone method, and scanning electron microscopy (SEM) imaging were conducted to study the synthesis of EPS by dual-species biofilms. Lactic acid assay and pH were measured to detect dual-species biofilm acid production. We found that norspermidine had different effects on S. mutans and S. sanguinis including their growth and biofilm formation. Norspermidine regulated the composition of the dual-species biofilms, decreased the ratio of S. mutans in dual-species biofilms, and reduced the metabolic activity, EPS synthesis, and acid production of dual-species biofilms. Norspermidine regulated dual-species biofilms in an ecological way, suggesting that it may be a potent reagent for controlling dental biofilms and managing dental caries.

scholarly journals Efficacy of Antifungal Monotherapies and Combinations againstAspergillus calidoustus

2018 ◽  
Vol 62 (12) ◽  
Author(s):  
E. Glampedakis ◽  
A. T. Coste ◽  
M. Aruanno ◽  
D. Bachmann ◽  
E. Delarze ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Therapeutic Range ◽  
Potential Benefit ◽  
Galleria Mellonella ◽  
Fungal Infections ◽  
Antifungal Drugs ◽  
Content Type ◽  
Content Model ◽  
Poor Outcomes

ABSTRACTInvasive fungal infections due toAspergillus calidoustuswith decreased azole susceptibility are emerging in the setting of azole prophylaxis and are associated with poor outcomes. We assessed thein vitroactivity of antifungal drugs used alone or in combinations againstA. calidoustusand found a synergistic effect between voriconazole and terbinafine at concentrations within the therapeutic range. An invertebrateGalleria mellonellamodel ofA. calidoustusinfection tended to support the potential benefit of this combination.

scholarly journals Pancreatic Amylase Is an Environmental Signal for Regulation of Biofilm Formation and Host Interaction in Campylobacter jejuni

2015 ◽  
Vol 83 (12) ◽  
pp. 4884-4895 ◽  
Author(s):  
Waheed Jowiya ◽  
Katja Brunner ◽  
Sherif Abouelhadid ◽  
Haitham A. Hussain ◽  
Sean P. Nair ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Biofilm Formation ◽  
Galleria Mellonella ◽  
Infection Model ◽  
Pancreatic Amylase ◽  
Content Type ◽  
Host Interaction ◽  
Food Borne ◽  
Epithelial Cell Lines

Campylobacter jejuniis a commensal bacterium in the intestines of animals and birds and a major cause of food-borne gastroenteritis in humans worldwide. Here we show that exposure to pancreatic amylase leads to secretion of an α-dextran byC. jejuniand that a secreted protease, Cj0511, is required. Exposure ofC. jejunito pancreatic amylase promotes biofilm formationin vitro, increases interaction with human epithelial cell lines, increases virulence in theGalleria mellonellainfection model, and promotes colonization of the chicken ileum. We also show that exposure to pancreatic amylase protectsC. jejunifrom stress conditionsin vitro, suggesting that the induced α-dextran may be important during transmission between hosts. This is the first evidence that pancreatic amylase functions as an interkingdom signal in an enteric microorganism.

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