Effects of elevated levels of intracellular nitric oxide on Pseudomonas aeruginosa biofilm in chronic skin wound and slow-killing infection models

Nitric oxide (NO), produced through the denitrification pathway, regulates biofilm dynamics through the quorum sensing system in Pseudomonas aeruginosa. NO stimulates P. aeruginosa biofilm dispersal by enhancing phosphodiesterase activity to decrease cyclic di-GMP levels. In a chronic skin wound model containing a mature biofilm, the gene expression of nirS, encoding nitrite reductase to produce NO, was low, leading to reduced intracellular NO levels. Although low-dose NO induces biofilm dispersion, it is unknown whether it influences the formation of P. aeruginosa biofilms in chronic skin wounds. In this study, a P. aeruginosa PAO1 strain with overexpressed nirS was established to investigate NO effects on P. aeruginosa biofilm formation in an ex vivo chronic skin wound model and unravel the underlying molecular mechanisms. Elevated intracellular NO levels altered the biofilm structure in the wound model by inhibiting the expression of quorum sensing–related genes, which was different from an in vitro model. In Caenorhabditis elegans as a slow-killing infection model, elevated intracellular NO levels increased worms’ lifespan by 18%. Worms that fed on the nirS-overexpressed PAO1 strain for 4 h had complete tissue, whereas worms that fed on empty plasmid–containing PAO1 had biofilms on their body, causing severe damage to the head and tail. Thus, elevated intracellular NO levels can inhibit P. aeruginosa biofilm growth in chronic skin wounds and reduce pathogenicity to the host. Targeting NO is a potential approach to control biofilm growth in chronic skin wounds wherein P. aeruginosa biofilms are a persistent problem. (AU)

Biofouling inhibition by Staphylococcus aureus extracts and their potential use for paints / Inhibición de la bioincrustación por extractos de Staphylococcus aureus y su uso potencial para pinturas

For the control of biofouling, some paints based on compounds that are toxic to marine organisms have been used. There is an intensive search for biodegradable solutions that are friendly to non-target organisms. Bacteria have been shown to be a source of compounds with antifouling potential. In this work, the antifouling activity of a strain of Staphylococcus aureus was evaluated. Extracts activity against biofilm-forming bacteria and the toxicity against Artemia franciscana were evaluated. The extracts were incorporated in a hard gel and a paint matrix, and they were exposed to the sea. In both the laboratory and field, we found that the compounds produced by S. aureus have antifouling activity. The non-toxicity of the tested extracts against Artemia franciscana nauplii suggests that the extracts obtained from S. aureus could have a low ecological impact over non-target organisms. Significant differences were found in the percentage of organisms cover in hard gels with extracts and control. After 90 days, important differences were also observed between the percentage of organisms cover of the paints that contained extracts and the control. Dichloromethane extract is the most effective for the inhibition or delay of the settlement of organisms For this reason, they could be used in matrices with different applications, such as in the shipping industry, aquaculture, or any other in which biofouling is a cause of inconvenience.(AU)

Gene expression during the development of Mycobacterium smegmatis biofilms on hydroxyapatite surfaces / Expresión génica durante el desarrollo de biopelículas de Mycobacterium smegmatis en superficies de hidroxiapatita

Bacterial biofilms are a consortium of bacteria that are strongly bound to each other and the surface on which they developed irreversibly. Bacteria can survive adverse environmental conditions and undergo changes when transitioning from a planktonic form to community cells. The process of mycobacteria adhesion is complex, involving characteristics and properties of bacteria, surfaces, and environmental factors; therefore, the formation of different biofilms is possible. Cell wall-, lipid-, and lipid transporter-related genes (glycopeptidolipids, GroEL1, protein kinase) are important in mycobacterial biofilm development. We investigated gene expression during in vitro development of Mycobacterium smegmatis biofilms on a hydroxyapatite (HAP) surface. Biofilm formation by M. smegmatis cells was induced for 1, 2, 3, and 5 days on the HAP surface. Mycobacteria on polystyrene generated an air–liquid interface biofilm, and on the fifth day, it increased by 35% in the presence of HAP. Six genes with key roles in biofilm formation were analyzed by real-time RT‒qPCR during the biofilm formation of M. smegmatis on both abiotic surfaces. The expression of groEL1, lsr2, mmpL11, mps, pknF, and rpoZ genes during biofilm formation on the HAP surface did not exhibit significant changes compared to the polystyrene surface. These genes involved in biofilm formation are not affected by HAP.(AU)

Halotolerant Citrobacter sp. remediates salinity stress and promotes the growth of Vigna radiata (L) by secreting extracellular polymeric substances (EPS) and biofilm formation: a novel active cell for microbial desalination cell (MDC) / Citrobacter sp. halotolerante. remedia el estrés salino y promueve el crecimiento de Vigna radiata (L) mediante la secreción de sustancias poliméricas extracelulares (EPS) y la formación de biopelículas: una nueva célula activa para la célula microbiana de desalinización (MDC)

To address soil salinization and its impact on crop production, microbial desalination cells (MDCs) offer a promising solution. These bioelectrochemical systems integrate desalination and wastewater treatment through microbial activity. A halotolerant beneficial bacterial strain called Citrobacter sp. strain KUT (CKUT) was isolated from India’s salt desert Run of Kutch, Gujrat, highlighting its potential application in combating soil salinization. CKUT exhibits high salt tolerance and has the ability to produce extracellular polymeric substances (EPS) at a concentration of 0.04 mg/ml. It forms biofilm that enable it to withstand up to 10% NaCl concentration. Additionally, CKUT shows promise in remediating salinity levels, reducing it from 4.5 to 2.7 gL−1. These characteristics are driven by biofilm formation and EPS production. In an experiment where V. radiata L. seedlings were inoculated with CKUT, the treated plants exhibited enhanced chlorophyll content, growth, and overall plant characteristics compared to seedlings treated with sodium chloride (NaCl). These improvements included increased shoot length (150 mm), root length (40 mm), and biomass. This indicates that CKUT treatment has the potential to enhance the suitability of V. radiata and other crops for cultivation in saline lands, effectively addressing the issue of soil salinization. Furthermore, integrating CKUT into microbial desalination cells (MDCs) offers an opportunity for freshwater production from seawater, contributing to sustainable agriculture by promoting improved crop growth and increased yield in areas prone to salinity.(AU)

Comparison of amphotericin B lipid complex, deoxycholate amphotericin B, fluconazole, and anidulafungin activity against Candida albicans biofilm isolated from breakthrough candidemia / Comparación de la actividad del complejo lipídico de anfotericina B, anfotericina B desoxicolato, fluconazol y anidulafungina frente al biofilrm de Candida albicans aisladas de candidemia de brecha

Introduction: Biofilm formation causes virulence and resistance in Candida albicans. However, little is known about breakthrough candidemia isolates. We evaluated the antifungal activity of fluconazole, anidulafungin, deoxycholate amphotericin B (dAMB), and amphotericin B lipid complex (ABLC) against biofilms of C. albicans isolated from patients with breakthrough candidemia. Methods: The present study used strains of C. albicans isolated from breakthrough and non-breakthrough candidemia patients (control group). The susceptibility of planktonic cells to amphotericin B, anidulafungin, and fluconazole was determined by broth microdilution. Antifungal activity in sessile cells was evaluated using the minimum biofilm eradication concentration (MBEC), metabolic activity was estimated by reducing MTT, and biomass was estimated using crystal violet retention. Results: The planktonic strains were susceptible to amphotericin B, anidulafungin, and fluconazole, with minimum inhibitory concentrations of 1, ≤0.03, and 2mg/L, respectively. However, fluconazole and anidulafungin did not exert an antifungal effect on biofilms. Additionally, dAMB and ABCL reduced the metabolic activity and biomass. However, eradication was only achieved using 16mg/L dAMB. C. albicans isolates of breakthrough candidemia exhibited strong biofilm production, and the in vitro activity of available therapeutic options was poor. Conclusion: In the present study, only dAMB and ABCL exhibited antibiofilm effects against sessile breakthrough candidemia isolates.(AU)

Introducción: La formación de biofilm se asocia con la virulencia y la resistencia al tratamiento de Candida albicans (C. albicans) sin embargo, son poco conocidas las características de los aislamientos procedentes de pacientes con candidemias de brecha. Evaluamos la actividad antifúngica de fluconazol, anidulafungina, anfotericina B desoxicolato (dAMB) y el complejo lipídico de la anfotericina B (ABLC) frente a biofilms de C. albicans aisladas de pacientes con candidemia de brecha. Métodos: Se utilizaron cepas de C. albicans aisladas de candidemias de brecha y de otras candidemias (grupo control). La sensibilidad de las células planctónicas a la anfotericina B, la anidulafungina y el fluconazol se determinó mediante el método de microdilución en caldo. En células sésiles, la actividad antifúngica se evaluó mediante la concentración miníma de erradicación de biofilm (MBEC), la actividad metabólica se estimó mediante la reducción de MTT y la biomasa mediante la retención de cristal violeta. Resultados: Las cepas en forma planctónica fueron sensibles a la anfotericina B, anidulafungina y fluconazol, con CMI de 1 mg/L, ≤ 0,03 y 2 mg/L, respectivamente; sin embargo, no se observó efecto antifúngico sobre los biofilms con fluconazol o anidulafungina. Con dAMB y ABCL se observó una reducción de la actividad metabólica y de la biomasa, pero la erradicación solo se consiguió con 16 mg/L de dAMB. Las cepas de C. albicans que causan candidemia de brecha producen abundante biofilm y las opciones terapéuticas disponibles no son activas in vitro frente a ellas. Conclusión: Solo dAMB y ABCL exhibieron efecto antibiofilm frente a los aislamientos de C. albicans sésiles y planctónicos.(AU)

Combating planktonic and biofilm growth of Serratia marcescens by repurposing ebselen / Combatir el crecimiento planctónico y de biopelículas de Serratia marcescens mediante la reutilización de ebselen

Aim of the study: The rising instances of multidrug-resistant pathogens are rapidly evolving into a global healthcare crisis. Identifying new ways of synthesis of antibiotics is both time-consuming and expensive. Repurposing existing drugs for the treatment of such antimicrobial-resistant pathogens has also been explored. Methods and results: In the current study, ebselen was screened for antibacterial and antibiofilm activity against Serratia marcescens. Various antibacterial studies such as minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), time-kill curves, intracellular reactive oxygen species (ROS) quantification, and colony-forming unit assays were performed. The antibiofilm potential was assayed by biofilm inhibition, cell surface hydrophobicity assay, eradication, quantification of extracellular DNA (eDNA), and extracellular polymeric substance (EPS) layer and scanning electron microscopy (SEM) analysis were performed. Anti-quorum sensing assay was validated by quantifying the virulence factors production. Further molecular docking of ebselen with two quorum sensing (QS) specific proteins was also carried out. Antibacterial susceptibility tests showed potent antimicrobial activity of ebselen against S. marcescens with MIC50 of 14 μg/mL. Ebselen’s ability to disturb the redox environment by inducing significant ROS generation led to bacterial death. It also showed concentration-dependent bactericidal activity as indicated by reduced bacterial growth and colony-forming unit propagation. Ebselen was also found to prevent biofilm attachment by altering the cell surface hydrophobicity while also being effective against preformed biofilms as validated by scanning electron microscopy (SEM) analysis. Additionally, ebselen showed reduced virulence factors like urease enzyme activity and prodigiosin pigment production indicating its promising anti-quorum sensing potential...(AU)

The phenotypes and genotypes associated with biofilm formation among methicillin-susceptible Staphylococcus aureus (MSSA) isolates collected from a tertiary hospital in Terengganu, Malaysia / Los fenotipos y genotipos asociados con la formación de biopelículas entre aislados de Staphylococcus aureus susceptibles a meticilina (MSSA) recolectados en un hospital terciario en Terengganu, Malasia

Methicillin-susceptible Staphylococcus aureus (MSSA) is an important nosocomial pathogen worldwide. This study aims to investigate the in vitro biofilm-forming ability of clinical MSSA isolated from various sources in the main public tertiary referral hospital in Terengganu, Malaysia and to detect the presence of biofilm-associated and regulatory genes among these isolates. A total of 104 MSSA isolates [pus (n = 75), blood (n = 24), respiratory secretions (n = 2), eye (n = 2), and urine (n = 1)] were investigated for slime production and biofilm formation using Congo red agar and crystal violet microtitre plate, respectively. Fifteen MSSA isolates with varying degrees of biofilm formation were selected for validation via a real-time cell analyser. All isolates were screened for microbial surface components recognising adhesive matrix molecules (MSCRAMM) and accessory gene regulator (agr) using polymerase chain reaction assay. A total of 76.0% (79/104) isolates produced slime layer, while all isolates developed biofilm as follows: 52.8% (55/104) strong biofilm producers, 40.4% (42/104) intermediate biofilm producers, and 6.7% (7/104) weak biofilm producers. A total of 98.1% (102/104) isolates carried at least one of the screened MSCRAMM gene(s) with the eno gene detected at the highest rate (87.5%, 91/104), while the sasG gene was significantly associated with strong biofilm production (p = 0.015). Three agr groups, 1, 2, and 3, were detected among the MSSA isolates with a predominance of agr-3 (32.7%, 34/104). In conclusion, biofilm formation varied greatly among clinical MSSA isolates, and the presence of sasG gene and agr-1 may play important role in initiating MSSA infections via biofilm formation.(AU)

The potential of Bacillus and Enterococcus probiotic strains to combat helicobacter pylori attachment to the biotic and abiotic surfaces / El potencial de las cepas probióticas de Bacillus y Enterococcus para combatir la adhesión de Helicobacter pylori a las superficies bióticas y abióticas

The prevention of biofilm formation plays a pivotal role in managing Helicobacter pylori inside the body and the environment. This study showed in vitro potentials of two recently isolated probiotic strains, Bacillus sp. 1630F and Enterococcus sp. 7C37, to form biofilm and combat H. pylori attachment to the abiotic and biotic surfaces. Lactobacillus casei and Bifidobacterium bifidum were used as the reference probiotics. The biofilm rates were the highest in the solid–liquid interface for Lactobacillus and Bifidobacterium and the air–liquid interface for Bacillus and Enterococcus. The highest tolerances to the environmental conditions were observed during the biofilm formations of Enterococcus and Bifidobacterium (pH), Enterococcus and Bacillus (bile), and Bifidobacterium and Lactobacillus (NaCl) on the polystyrene and glass substratum, respectively. Biofilms occurred more quickly by Bacillus and Enterococcus strains than reference strains on the polystyrene and glass substratum, respectively. Enterococcus (competition) and Bacillus (exclusion) achieved the most inhibition of H. pylori biofilm formations on the polystyrene and AGS cells, respectively. Expression of luxS was promoted by Bacillus (exclusion, 3.2 fold) and Enterococcus (competition, 2.0 fold). Expression of ropD was decreased when H. pylori biofilm was excluded by Bacillus (0.4 fold) and Enterococcus (0.2 fold) cells. This study demonstrated the ability of Bacillus and Enterococcus probiotic bacteria to form biofilm and combat H. pylori biofilm formation.(AU)

Quorum-quenching potential of recombinant PvdQ-engineered bacteria for biofilm formation / Potencial de eliminación de quórum de bacterias modificadas con PvdQ recombinante para la formación de biopelículas

Quorum sensing (QS) is a core mechanism for bacteria to regulate biofilm formation, and therefore, QS inhibition or quorum quenching (QQ) is used as an effective and economically feasible strategy against biofilms. In this study, the PvdQ gene encoding AHL acylase was introduced into Escherichia coli (DE3), and a PvdQ-engineered bacterium with highly efficient QQ activity was obtained and used to inhibit biofilm formation. Gene sequencing and western blot analysis showed that the recombinant pET-PvdQ strain was successfully constructed. The color reaction of Agrobacterium tumefaciens A136 indicated that PvdQ engineering bacteria had shown strong AHL signal molecule quenching activity and significantly inhibited the adhesion (motility) of Pseudomonas aeruginosa and biofilm formation of activated sludge bacteria in Membrane Bio-Reactor (MBR; inhibition rate 51–85%, p < 0.05). In addition, qRT-PCR testing revealed that recombinant PvdQ acylase significantly reduced the transcription level of QS biofilm formation-related genes (cdrA, pqsA, and lasR; p < 0.05). In this study, QQ genetically engineered bacteria enhanced by genetic engineering could effectively inhibit the QS signal transduction mechanism and have the potential to control biofilm formation of pathogenic bacteria in the aquaculture environment, providing an environmentally friendly and alternative antibiotic strategy to suppress biofilm contamination.(AU)

Antibiofilm activity of a lytic Salmonella phage on different Salmonella enterica serovars isolated from broiler farms / Actividad antibiopelícula de un fago lítico de Salmonella en diferentes serovares de Salmonella enterica aislados de granjas de pollos de engorde

Bacteriophages have been mainly used in treating infections caused by planktonic bacterial cells in the veterinary sector. However, their applications as antibiofilm agents have received little attention. Accordingly, a previously isolated Salmonella infecting Siphoviridae phage was investigated for host range against 15 Salmonella enterica isolates (S. Cape, S. Gallinarum, 4 S. Enteritidis, 3 S. Montevideo, S. Uno, S. Oritamerin, S. Belgdam, S. Agona, S. Daula, and S. Aba) recovered from the litters of commercial broiler farms. All S. enterica isolates were examined for their biofilm activity using a microtiter plate assay and for adrA, csgD, and gcpA genes using conventional PCR. The phage efficacy against established biofilms produced by the selected seven S. enterica isolates (S. Gallinarum, S. Enteritidis, S. Montevideo, S. Uno, S. Oritamerin, S. Belgdam, and S. Agona) was assessed using microtiter plate assay and reverse transcriptase real-time PCR over different incubation times of 5 and 24 h. All S. enterica isolates were strong biofilm formers. Moreover, the phage effectively reduced the biofilm activity of the established S. enterica biofilms in the microtiter plate assay using the independent sample t-test (P < 0.050). Furthermore, the relative expression levels of csgD, gcpA, and adrA genes in the biofilm cells of S. enterica isolate after phage treatment were significantly up-regulated to variable degrees using the independent sample t-test (P < 0.050). In conclusion, the present study revealed the potential use of Salmonella phage in reducing established biofilms produced by S. enterica serovars isolated from broiler farms.(AU)

Characterization, antifungal susceptibility and virulence of Candida parapsilosis complex isolates in a tertiary hospital in Cantabria, Northern Spain / Caracterización, sensibilidad antifúngica y virulencia de aislamientos del complejo Candida parapsilosis en un hospital terciario en Cantabria, norte de España

Introduction: The correct identification of the species within the Candida parapsilosis complex has become relevant due to the resistance of Candida metapsilosis to antifungals. We describe the characteristics of the Candida parapsilosis complex isolates, with respect to antifungal resistance and biofilm formation. Methods: We perform a descriptive cross-sectional study in 30 strains, collected in a tertiary hospital. All strains, were identified by Vitek2, Vitek-MS™ systems and by ITS sequencing. The antifungal susceptibility profile was obtained with Sensititre™ panels, while biomass production and metabolic activity were quantified by means of crystal violet and XTT reduction assay, respectively. Results: There was a 100% correlation between Vitek-MS™ and ITS sequencing. All isolates were susceptible to the nine antifungals tested. The metabolic activity and biomass production tests did not show any difference among the subtypes. Conclusions: The Vitek-MS™ system provides acceptable identification. We did not find significant differences neither in azole resistance nor in biofilm formation.(AU)

Introducción: La correcta identificación del complejo Candida parasilopsis es relevante debido a la resistencia antifúngica de Candida metasilopsis. Describimos las características de aislados del complejo Candida parapsilosis respecto a la resistencia antifúngica y formación de biopelícula. Métodos: Se realiza un estudio descriptivo transversal de 30 cepas recolectadas en un hospital terciario. Todas se identificaron por los sistemas Vitek2, MALDI-TOF MS Vitek-MSTM y por secuenciación de las regiones ITS. La sensibilidad antifúngica se realizó con paneles SensititreTM. Para la producción de biomasa y la actividad metabólica se emplearon la medición de cristal violeta y el ensayo de reducción de XTT, respectivamente. Resultados: Hubo una correlación del 100% entre Vitek-MSTM y la secuencia de ITS. Todos los aislados fueron sensibles a los 9 antifúngicos evaluados. Los ensayos de actividad metabólica y producción de biomasa no arrojaron diferencias entre los subtipos. Conclusiones: El sistema Vitek-MSTM proporciona una identificación aceptable. No encontramos diferencias significativas ni en la resistencia a azoles ni en la formación de biopelículas.(AU)

A study on the antibacterial activity and antimicrobial resistance of pyridinium cationic pillar[5]arene against Staphylococcus aureus and Escherichia coli / Un estudio sobre la actividad antibacteriana y la resistencia antimicrobiana del pilar catiónico de piridinio[5]areno contra Staphylococcus aureus y Escherichia coli

An increasing number of infections caused by multidrug-resistant (MDR) Staphylococcus aureus （S. aureus） and Escherichia coli （E. coli） have severely affected human society. Thus, it is essential to develop an alternative type of antibacterial agents that has a different bacterial resistance mechanism from that of traditional antibiotics. After the synthesis and structural characterization of a cationic pillar[5]arene with pyridinium groups (PP5), the antibacterial and antibiofilm activities as well as its microbial resistance were systematically investigated. In-depth evaluation of biological studies revealed that PP5 was an active antibacterial agent, with surprising antibiofilm formation ability against E. coli and S. aureus. From the results of differential scanning calorimetry and transmission electron microscopy, it was concluded that the microbicidal activity of PP5 was due to the physical disruption of the pathogen’s membrane and the subsequent leakage of cytoplasmic components, which could greatly reduce the rapid generation of resistance. It was presented that the easily available PP5 has high activity to inhibit Gram-positive and Gram-negative bacteria and/or their biofilms with low cytotoxicity. This pillar[5]arene derivative can be used as a good candidate for controlling drug-resistant pathogenic bacterial infections and treating MDR bacteria.(AU)

Biofilm formation of Salmonella enterica serovar Enteritidis cocultured with Acanthamoeba castellanii responds to nutrient availability / La formación de biopelículas de Salmonella enterica serovar Enteritidis cocultivada con Acanthamoeba castellanii responde a la disponibilidad de nutrientes

Acanthamoeba spp. and Salmonella share common habitats, and their interaction may influence the biofilm-forming ability of Salmonella. In this study, biofilm formation of Salmonella enterica serovar Enteritidis cocultured with Acanthamoeba castellanii was examined in nutrient-rich and nutrient-deficient media. Furthermore, transcript copy number of biofilm-related genes in the biofilm cells of S. Enteritidis in monoculture was compared to those in coculture with A. castellanii. Results demonstrated that the presence of A. castellanii in the culture media activates the genes involved in the biofilm formation of S. Enteritidis, regardless of the nutrient availability. However, biofilm formation of S. Enteritidis cocultured with A. castellanii was not consistent with the transcript copy number results. In nutrient-rich medium, the number of Salmonella biofilm cells and the contents of the three main components of the biofilms including eDNA, protein, and carbohydrates were higher in the presence of A. castellanii compared to monocultures. However, in nutrient-deficient medium, the number of biofilm cells, and the amount of biofilm components in coculture conditions were less than the monocultures. These results indicate that despite activation of relevant genes in both nutrient-rich and nutrient-deficient media, biofilm formation of S. Enteritidis cocultured with A. castellanii responds to nutrient availability.(AU)

Tec1 and Ste12 transcription factors play a role in adaptation to low pH stress and biofilm formation in the human opportunistic fungal pathogen Candida glabrata / Los factores de transcripción de Tec1 y Ste12 juegan un papel en la adaptación al estrés de pH bajo y la formación de biopelículas en el patógeno fúngico oportunista humano Candida glabrata

Eukaryotic cells respond to environmental cues through mitogen activated protein kinase (MAPK) signaling pathways. Each MAPK cascade is specific to particular stimuli and mediates specialized responses through activation of transcription factors. In the budding yeast, Saccharomyces cerevisiae, the pheromone-induced mating pathway and the starvation-responsive invasive growth/filamentation pathway generate their distinct outputs through the transcription factors Ste12 and Tec1, respectively. In this study, we report the functional characterization of these transcription factors in the closely related human opportunistic pathogenic yeast Candida glabrata. Two homologues each for S. cerevisiae TEC1 and STE12 were identified in C. glabrata. Both C. glabrata Tec1 proteins contain the N-terminal TEA DNA-binding domain characteristic of the TEA/ATTS transcription factor family. Similarly, the DNA-binding homeodomain shared by members of the highly conserved fungal Ste12 transcription factor family is present in N-terminus of both C. glabrata Ste12 transcription factors. We show that both C. glabrata STE12 genes are at least partial functional orthologues of S. cerevisiae STE12 as they can rescue the mating defect of haploid S. cerevisiae ste12 null mutant. Knockout of one of the STE12 genes (ORF CAGL0H02145g) leads to decreased biofilm development; a stronger biofilm-impaired phenotype results from loss of both CgSTE12 genes in the double deletion mutant (Cgste12ΔΔ). The transcript levels of one of the TEC1 genes (ORF CAGL0M01716g) were found to be upregulated upon exposure to low pH; its deletion causes slightly increased sensitivity to higher concentrations of acetic acid. Heat shock leads to increase in mRNA levels of one of the STE12 genes (ORF CAGL0M01254g).(AU)

Production of biofilm by Staphylococcus aureus: Association with infective endocarditis? / Producción de biofilm en Staphylococcus aureus: ¿Asociación con endocarditis infecciosa?

Objectives: Staphylococcus aureus is a well-known biofilm-producing pathogen that is capable of causing chronic infections owing to its ability to resist antibiotic treatment and obstruct the immune response. However, the possible association between high biofilm production and infective endocarditis (IE) has not been assessed. Our objective was to compare production of biofilm by S. aureus strains isolated from patients with bacteremia and IE, catheter-related bloodstream infection (C-RBSI), or non-device associated bacteremia. Methods: We isolated 260 S. aureus strains from the blood of patients with bacteremia who were diagnosed during hospital admission between 2012 and 2015. Patients were divided into 3 groups according to whether they had IE, C-RBSI, or non-device associated bacteremia. Biofilm production was measured in terms of biomass and metabolic activity using the crystal violet and XTT assays, respectively. High biomass and metabolic activity rates (based on tertile ranks classification) were compared between the 3 groups. Results: The high biomass and metabolic activity rates of each group were 41.9% and 37.2% for IE, 32.5% and 35.0%, for C-RBSI, and 29.0% and 33.3% for non-device associated bacteremia (p=0.325 and p=0.885, respectively). Conclusions: High biomass and metabolic activity levels for S. aureus isolates from IE were similar to those of S. aureus isolates from C-RBSI or non-device associated bacteremia.(AU)

Objetivos: Staphylococcus aureus es un conocido microorganismo productor de biofilm, capaz de causar infecciones crónicas debido a su capacidad de resistir el tratamiento antibiótico y dificultar la respuesta inmunitaria. Sin embargo, no se ha evaluado la posible asociación entre una elevada producción de biofilm y la endocarditis infecciosa (EI). Nuestro objetivo fue comparar la producción de biofilm por parte de cepas de S.aureus aisladas de pacientes con bacteriemia y EI, bacteriemia relacionada con el catéter (BRC) o bacteriemia no asociada a dispositivos. Métodos: Se aislaron 260 cepas de S.aureus de sangre de pacientes con bacteriemia que fueron diagnosticados durante su ingreso hospitalario entre 2012 y 2015. Los pacientes se dividieron en tres grupos según tuvieran EI, BRC o bacteriemia no asociada a dispositivos. La producción de biofilm se midió en términos de biomasa y de actividad metabólica utilizando los ensayos de cristal violeta y XTT, respectivamente. Se compararon los índices de alta biomasa y actividad metabólica (basadas en clasificación por terciles) entre los tres grupos. Resultados: Los índices altos de biomasa y actividad metabólica de cada grupo fueron del 41,9 y del 37,2% para EI, del 32,5 y del 35,0% para BRC, y del 29,0 y del 33,3% para bacteriemia no asociada a dispositivos (p=0,325 y p=0,885, respectivamente). Conclusiones: Los niveles altos de biomasa y actividad metabólica de los aislados de S.aureus procedentes de EI fueron similares a los de los aislados de BRC o de bacteriemia no asociada a dispositivos.(AU)

Analysis of biofilm production and expression of adhesion structures of circulating Clostridioides difficile strains from Mexico / Análisis de la producción de biopelícula y expresión de estructuras de adhesión de cepas circulantes de Clostridioides difficile en México

Introduction: Clostridioides difficile biofilms are believed to protect the pathogen from antibiotics, in addition to potentially contributing to recurrent infections. Methodology: Biofilm production of 102 C. difficile isolates was determined using the crystal violet staining technique, and detachment assays were performed. The expression levels of cwp84 and slpA genes were evaluated by real-time PCR on selected isolates. Results: More than 70% of isolates (75/102) were strong biofilm producers, and the highest detachment of biofilm was achieved with the proteinase K treatment (>90%). The overall mean expression of cwp84 was higher in RT027 than in RT001 (p=0.003); among strong biofilm-producing strains, the slpA expression was lower in RT027 than in RT001 (p<0.000). Conclusions: Proteins seem to have an important role in the biofilm's initial adherence and maturation. slpA and cwp84 are differentially expressed by C. difficile ribotype and biofilm production level.(AU)

Introducción: Se cree que las biopelículas de Clostridioides difficile (C. difficile) protegen al patógeno de los antibióticos, además de contribuir potencialmente a las infecciones recurrentes. Metodología: Se determinó la producción de biopelículas de 102 aislados de C. difficile, mediante la técnica de tinción con violeta cristal y se realizaron ensayos de desprendimiento. Los niveles de expresión de los genes cwp84 y slpA se evaluaron mediante PCR en tiempo real en aislados seleccionados. Resultados: Más del 70% de los aislados (75/102) fueron fuertes productores de biopelículas y el mayor desprendimiento de biopelícula se logró con el tratamiento con proteinasa K (> 90%). La expresión media global de cwp84 fue mayor en RT027 que en RT001 (p = 0,003); entre las cepas productoras fuertes de biopelícula, la expresión de slpA fue menor en RT027 que en RT001 (p < 0,000). Conclusiones: Las proteínas parecen tener un papel importante en la adhesión y maduración inicial de las biopelículas; slpA y cwp84 se expresan de forma diferente según el ribotipo de C. difficile y el nivel de producción de biopelículas.(AU)