Laser NIR Irradiation Enhances Antimicrobial Photodynamic Inactivation of Biofilms of Staphylococcus aureus.

Objectives: Photodynamic inactivation (PDI) is a powerful technique for eradicating microorganisms, and our group previously demonstrated its effectiveness against planktonic cultures of Staphylococcus aureus bacteria using 5,10,15,20-tetrakis[4-(3-N,N-dimethylaminopropoxy)phenyl]porphyrin (TAPP) and visible light irradiation. However, biofilms exhibit a lower sensitivity to PDI, mainly due to limited penetration of the photosensitizer (PS). In the context of emerging antibacterial strategies, near-infrared treatments (NIRTs) have shown promise, especially for combating resistant strains.

The Impact of Low-Level Benzalkonium Chloride Exposure on spp. Strains and Control by Photoinactivation.

Exposure of bacteria to low concentrations of biocides can facilitate horizontal gene transfer, which may lead to bacterial adaptive responses and resistance to antimicrobial agents. The emergence of antibacterial resistance not only poses a significant concern to the dairy industry but also adds to the complexity and cost of mastitis treatment. This study was aimed to evaluate how selective stress induced by benzalkonium chloride (BC) promotes antibiotic non-susceptibility in spp.

Multiclonal human origin and global expansion of an endemic bacterial pathogen of livestock.

Most new pathogens of humans and animals arise via switching events from distinct host species. However, our understanding of the evolutionary and ecological drivers of successful host adaptation, expansion, and dissemination are limited. is a major bacterial pathogen of humans and a leading cause of mastitis in dairy cows worldwide.

Growth conditions affect biofilms of producing mastitis: Contribution of MALDI-TOF-MS to strain characterization.

Bovine mastitis is a disease of dairy cattle prevalent throughout the world that causes alterations in the quality and composition of milk, compromising technological performance. is one of the most important pathogens that produce clinical, subclinical, and chronic mastitis. Biofilms are considered a virulence factor necessary for the survival of in the mammary gland.

Salicylic acid stabilizes Staphylococcus aureus biofilm by impairing the agr quorum-sensing system.

Salicylic acid (SAL) has recently been shown to induce biofilm formation in Staphylococcus aureus and to affect the expression of virulence factors. This study was aimed to investigate the effect of SAL on the regulatory agr system and its impact on S. aureus biofilm formation.

Acapsular Staphylococcus aureus with a non-functional agr regains capsule expression after passage through the bloodstream in a bacteremia mouse model.

Selection pressures exerted on Staphylococcus aureus by host factors during infection may lead to the emergence of regulatory phenotypes better adapted to the infection site. Traits convenient for persistence may be fixed by mutation thus turning these mutants into microevolution endpoints. The feasibility that stable, non-encapsulated S.

Photodynamic inactivation mediated by 5-aminolevulinic acid of bacteria in planktonic and biofilm forms.

Bacterial photodynamic inactivation (PDI) employing endogenous production of porphyrins from 5-aminolevulinic acid (ALA) - named ALA-PDI-, is a new promising tool to achieve bacteria control in non-spread infections. The technique combines the action of the porphyrins acting as photosensitisers with light, to produce reactive oxygen species to target the pathogen. To date, some clinical applications of ALA-PDI have been reported although variable responses ranging from total eradication to absence of photokilling were found.

Within-host evolution of bovine Staphylococcus aureus selects for a SigB-deficient pathotype characterized by reduced virulence but enhanced proteolytic activity and biofilm formation.

Staphylococcus aureus is a major cause of bovine mastitis, commonly leading to long-lasting, persistent and recurrent infections. Thereby, S. aureus constantly refines and permanently adapts to the bovine udder environment.

The anti MRSA biofilm activity of Thymus vulgaris essential oil in nanovesicles.

Background: Thymus vulgaris essential oil (T) could be an alternative to classical antibiotics against bacterial biofilms, which show increased tolerance to antibiotics and host defence systems and contribute to the persistence of chronic bacterial infections.

Hypothesis: A nanovesicular formulation of T may chemically protect the structure and relative composition of its multiple components, potentially improving its antibacterial and antibiofilm activity.

Study Design: We prepared and structurally characterized T in two types of nanovesicles: nanoliposomes (L80-T) made of Soybean phosphatidylcholine (SPC) and Polysorbate 80 (P80) [SPC:P80:T 1:0.

Distinct phenotypic traits of Staphylococcus aureus are associated with persistent, contagious bovine intramammary infections.

Staphylococcus aureus causing persistent, recurrent bovine intramammary infections are still a major challenge to dairy farming. Generally, one or a few clonal lineages are predominant in dairy herds, indicating animal-to-animal transfers and the existence of distinct pathotypic traits. The aim of this study was to determine if long term persistence and spreading of S.

Mutation of Agr Is Associated with the Adaptation of to the Host during Chronic Osteomyelitis.

Selection pressures exerted on by host factors may lead to the emergence of mutants better adapted to the evolving conditions at the infection site. This study was aimed at identifying the changes that occur in exposed to the host defense mechanisms during chronic osteomyelitis and evaluating whether these changes affect the virulence of the organism. Genome assessment of two isolates collected 13 months apart (HU-85a and HU-85c) from a host with chronic osteomyelitis was made by whole genome sequencing.

Enhancement of photodynamic inactivation of Staphylococcus aureus biofilms by disruptive strategies.

Photodynamic inactivation (PDI) has been used to inactivate microorganisms through the use of photosensitizers and visible light. On the one hand, near-infrared treatment (NIRT) has also bactericidal and dispersal effects on biofilms. In addition, dispersal biological tools such as enzymes have also been employed in antibiotic combination treatments.

The Active Component of Aspirin, Salicylic Acid, Promotes Biofilm Formation in a PIA-dependent Manner.

Aspirin has provided clear benefits to human health. But salicylic acid (SAL) -the main aspirin biometabolite- exerts several effects on eukaryote and prokaryote cells. SAL can affect, for instance, the expression of virulence factors.

Sae regulator factor impairs the response to photodynamic inactivation mediated by Toluidine blue in Staphylococcus aureus.

Photodynamic inactivation (PDI) involves the combined use of light and a photosensitizer, which, in the presence of oxygen, originates cytotoxic species capable of inactivating bacteria. Since the emergence of multi-resistant bacterial strains is becoming an increasing public health concern, PDI becomes an attractive choice. The aim of this work was to study the differential susceptibility to Toluidine blue (TB) mediated PDI (TB-PDI) of S.

Genotyping and study of the pauA and sua genes of Streptococcus uberis isolates from bovine mastitis.

This study aimed to determine the clonal relationship among 137 Streptococcus uberis isolates from bovine milk with subclinical or clinical mastitis in Argentina and to assess the prevalence and conservation of pauA and sua genes. This information is critical for the rational design of a vaccine for the prevention of bovine mastitis caused by S. uberis.

Salmonella enterica serovar Enteritidis enterocolitis during late stages of gestation induces an adverse pregnancy outcome in the murine model.

Foodborne diseases caused by Salmonella enterica serovar Enteritidis (S. Enteritidis) are a significant health problem. Pregnancy, state of immunological tolerance, is a predisposing condition for the development of infections with intracellular pathogens.

Dam methylation regulates the expression of SPI-5-encoded sopB gene in Salmonella enterica serovar Typhimurium.

DNA adenine methylation is an essential factor in Salmonella virulence. Here, we investigate the involvement of DNA adenine methylase (Dam) in the expression and translocation of a SPI-5-encoded effector of S. Typhimurium.

AvrA effector protein of Salmonella enterica serovar Enteritidis is expressed and translocated in mesenteric lymph nodes at late stages of infection in mice.

Salmonellosis is a major health problem worldwide. Salmonella enterica serovar Enteritidis (S. Enteritidis) has been a primary cause of Salmonella outbreaks in many countries.

Protein antigens increase the protective efficacy of a capsule-based vaccine against Staphylococcus aureus in a rat model of osteomyelitis.

Staphylococcus aureus is an invasive bacterial pathogen, and antibiotic resistance has impeded adequate control of infections caused by this microbe. Moreover, efforts to prevent human infections with single-component S. aureus vaccines have failed.

Rapid and reliable identification of Staphylococcus aureus capsular serotypes by means of artificial neural network-assisted Fourier transform infrared spectroscopy.

Staphylococcus aureus capsular polysaccharides (CP) are important virulence factors and represent putative targets for vaccine development. Therefore, the purpose of this study was to develop a high-throughput method to identify and discriminate the clinically important S. aureus capsular serotypes 5, 8, and NT (nontypeable).

Aromatic Compound-Dependent Staphylococcus aureus Is Safe in a Nasal Colonization Leukopenic Murine Model.

Staphylococcus aureus nasal carriage is a risk factor for individuals suffering from trauma, surgical procedures, invasive devices, and/or decreased immunity. Recently, we demonstrated that artificial nasal colonization with an attenuated S. aureus mutant reduced by bacterial interference with the colonization of pathogenic strains of S.

Phenotypic and genotypic characterization of Streptococcus uberis isolated from bovine subclinical mastitis in Argentinean dairy farms.

The aim of this study was to investigate the phenotypic and genotypic characteristics of Streptococcus uberis isolated from subclinical mastitis (SCM) cases, and to examine the possible association between both characteristics. A total of 32 S. uberis were isolated from 772 quarter milk samples (SCM > 250,000 cells/ml) collected from 195 cows selected randomly from 18 dairy farms located in Argentina.

Auxotrophic mutant of Staphylococcus aureus interferes with nasal colonization by the wild type.

Staphylococcus aureus nasal carriage is a risk factor for infection in humans, particularly in the hospital setting. Bacterial interference was used as an alternative strategy for the prevention of upper respiratory, urogenital and gastrointestinal tract infections. This study was designed to assess if the administration of a live-attenuated aroA mutant of S.

Salicylic acid enhances Staphylococcus aureus extracellular adhesin protein expression.

One of the virulence factors required by Staphylococcus aureus at the early stages of infection is Eap, a secreted adhesin that binds many host proteins and is upregulated by the two-component regulatory system saeRS. The S. aureus Newman strain harbors a mutation in saeS that is thought to be responsible for the high level of Eap expression in this strain.

Staphylococcus aureus adaptation to the host and persistence: role of loss of capsular polysaccharide expression.

A vast array of virulence factors enable Staphylococcus aureus to readily adapt to different environmental niches in diverse hosts. The cap gene cluster is present in almost all relevant clinical S. aureus isolates and capsular polysaccharide expression is apparent in isolates from patients with acute infection.