A Study on the Epidemiological-Molecular Role of Strains in the Development of Ventilator-Associated Pneumonia in a Tertiary Hospital in Brazil.

This study aimed to explore the molecular epidemiology of isolated from patients on mechanical ventilation and the participation of virulence factors in the development of ventilator-associated pneumonia (VAP). A prospective cohort study was conducted on patients under mechanical ventilation, with periodic visits for the collection of tracheal aspirates and clinical data. The isolates were analyzed regarding resistance profile, virulence, expression of protein A and alpha-toxin using Western blot, clonal profile using PFGE, sequence type using MLST, and characterization and quantification of phenol-soluble modulins.

Acidonemycins A-C, Glycosylated Angucyclines with Antivirulence Activity Produced by the Acidic Culture of .

The genome of is highly enriched with cryptic biosynthetic gene clusters (BGCs). The majority of these cryptic BGCs are transcriptionally silent in normal laboratory culture conditions as determined by transcriptome analysis. When cultured in acidic pH (pH 5.

Discovery of Bioactive Metabolites by Acidic Stress to a Geldanamycin Producer, .

In an effort to activate silent biosynthetic gene clusters, DSM42010, a producer of geldanamycin, was cultured at four different pHs (4.5, 5.4, 6.

New meroterpenoids from a soil-derived fungus Penicillium sp. SSW03M2 GY and their anti-virulence activity.

Two new berkeley meroterpenoids (1 and 2), along with seven known compounds (3‒9) were isolated from a fungus, Penicillium sp. SSW03M2 GY derived from a sediment at Seosan bay, South Korea. Chemical structures of the isolated compounds were elucidated on the basis of 1D, 2D NMR, HRESIMS, and optical rotation.

Molecular Basis of Non-β-Lactam Antibiotics Resistance in .

Methicillin-resistant (MRSA) is one of the most successful human pathogens with the potential to cause significant morbidity and mortality. MRSA has acquired resistance to almost all β-lactam antibiotics, including the new-generation cephalosporins, and is often also resistant to multiple other antibiotic classes. The expression of penicillin-binding protein 2a (PBP2a) is the primary basis for β-lactams resistance by MRSA, but it is coupled with other resistance mechanisms, conferring resistance to non-β-lactam antibiotics.

Arctic Psychrotolerant sp. B14-6 Exhibits Temperature-Dependent Susceptibility to Aminoglycosides.

Bacteria can evade antibiotics by acquiring resistance genes, as well as switching to a non-growing dormant state without accompanying genetic modification. Bacteria in this quiescent state are called persisters, and this non-inheritable ability to withstand multiple antibiotics is referred to as antibiotic tolerance. Although all bacteria are considered to be able to form antibiotic-tolerant persisters, the antibiotic tolerance of extremophilic bacteria is poorly understood.

Genotypes of Clinical Isolates Are Associated with Phenol-Soluble Modulin (PSM) Production.

Phenol-soluble modulins (PSMs) are important virulence factors that cause cytolysis, mast cell degranulation, and stimulate inflammatory responses. In this study, PSM production by clinical isolates was measured by liquid chromatography/mass spectrometry (LC-MS) and correlated with staphylococcal protein A () type and staphylococcal cassette chromosome (SCC) type. Of 106 clinical isolates, 50 (47.

Simultaneous monitoring of each component on degradation of blended bioplastic using gas chromatography-mass spectrometry.

The increasing interest in bioplastics, with regard to future environmental issues, has rendered research on bioplastic biodegradation highly important. However, only a few tools directly monitor the degradation of bioplastics without measuring the levels of gaseous products, such as carbon dioxide. Classical nonquantitative methods, such as clear zone tests on solid plates, and less-sensitive weight-loss experiments in liquid media measured using a precision scale, are still employed to screen the microbial players associated with bioplastic degradation and monitor the biodegradation rates.

Leucyl-tRNA Synthetase Inhibitor, D-Norvaline, in Combination with Oxacillin, Is Effective against Methicillin-Resistant .

Methicillin-resistant (MRSA) is a pathogenic bacterium that causes severe diseases in humans. For decades, MRSA has acquired substantial resistance against conventional antibiotics through regulatory adaptation, thereby posing a challenge for treating MRSA infection. One of the emerging strategies to combat MRSA is the combinatory use of antibacterial agents.

4-Chloro-2-Isopropyl-5-Methylphenol Exhibits Antimicrobial and Adjuvant Activity against Methicillin-Resistant .

Methicillin-resistant (MRSA) causes severe infections and poses a global healthcare challenge. The utilization of novel molecules which confer synergistical effects to existing MRSA-directed antibiotics is one of the well-accepted strategies in lieu of development of new antibiotics. Thymol is a key component of the essential oil of plants in the and .

Thymol Reduces -Mediated Virulence Factor Phenol-Soluble Modulin Production in .

is a major human bacterial pathogen that carries a large number of virulence factors. Many virulence factors of are regulated by the accessory gene regulator () quorum-sensing system. Phenol-soluble modulins (PSMs) are one of the -mediated virulence determinants known to play a significant role in pathogenesis.

Comparative Study of the Difference in Behavior of the Accessory Gene Regulator (Agr) in USA300 and USA400 Community-Associated Methicillin-Resistant (CA-MRSA).

Community-associated Methicillin-Resistant (CA-MRSA) is notorious as a leading cause of soft tissue infections. Despite several studies on the Agr regulator, the mechanisms of action of Agr on the virulence factors in different strains are still unknown. To reveal the role of Agr in different CA-MRSA, we investigated the LACΔ mutant and the MW2Δ mutant by comparing LAC (USA300), MW2 (USA400), and Δ mutants.

Unusual bridged angucyclinones and potent anticancer compounds from Streptomyces bulli GJA1.

Two new unique angucyclinones (1 and 2) with unprecedented ether bridges connecting carbons 5 and 7 were isolated from the cultures of Streptomyces bulli GJA1, an endophyte of Gardenia jasminoides, together with two known ones (3 and 4). The MS-based molecular networking system facilitated the isolation of compounds with target functionalities. The stereochemistry of 1 was completely established by ROESY and ECD experiments.

Increased Antibiotic Resistance of Methicillin-Resistant USA300 Δ Mutants and a Complementation Study of Δ Mutants Using Synthetic Phenol-Soluble Modulins.

Phenol-soluble modulins (PSMs) are responsible for regulating biofilm formation, persister cell formation, expression, host cell lysis, and anti-bacterial effects. To determine the effect of deletion on methicillin-resistant , we investigated deletion mutants including Δ, Δ, and Δ;. These mutants exhibited increased β-lactam antibiotic resistance to ampicillin and oxacillin that was shown to be caused by increased Nacetylmannosamine kinase () mRNA expression, which regulates persister cell formation, leading to changes in the pattern of phospholipid fatty acids resulting in increased anteiso-C, and increased membrane hydrophobicity with the deletion of PSMs.

Multi-omics based characterization of antibiotic response in clinical isogenic isolates of methicillin-susceptible/-resistant .

As demands for new antibiotics and strategies to control methicillin-resistant (MRSA) increase, there have been efforts to obtain more accurate and abundant information about the mechanism of the bacterial responses to antibiotics. However, most of the previous studies have investigated responses to antibiotics without considering the genetic differences between MRSA and methicillin-susceptible (MSSA). Here, we initially applied a multi-omics approach into the clinical isolates (, WKZ-1 (MSSA) and WKZ-2 (MRSA)) that are isogenic except for the mobile genetic element called staphylococcal cassette chromosome (SCC) type IV to explore the response to β-lactam antibiotics (oxacillin).

Increased resistance of a methicillin-resistant Staphylococcus aureus Δagr mutant with modified control in fatty acid metabolism.

Methicillin-resistant Staphylococcus aureus (MRSA) strains are distinct from general Staphylococcus strains with respect to the composition of the membrane, ability to form a thicker biofilm, and, importantly, ability to modify the target of antibiotics to evade their activity. The agr gene is an accessory global regulator of gram-positive bacteria that governs virulence or resistant mechanisms and therefore an important target for the control of resistant strains. However, the mechanism by which agr impacts resistance to β-lactam antibiotics remains unclear.

Phenol-Soluble Modulin-Mediated Aggregation of Community-Associated Methicillin-Resistant in Human Cerebrospinal Fluid.

Phenol-soluble modulins (PSMs) are major determinants of virulence and their increased production in community-associated methicillin-resistant (CA-MRSA) likely contributes to the enhanced virulence of MRSA strains. Here, we analyzed the differences in bacterial cell aggregation according to PSM presence in the specific human cerebrospinal fluid (CSF) environment. CSF samples from the intraventricular or lumbar intrathecal area of each patient and tryptic soy broth media were mixed at a 1:1 ratio, inoculated with WT and PSM-deleted mutants (Δpsm) of the CA-MRSA strain, USA300 LAC, and incubated overnight.

Biofilm Formation by Clinical Isolates is Differentially Affected by Glucose and Sodium Chloride Supplemented Culture Media.

() causes persistent biofilm-related infections. Biofilm formation by is affected by the culture conditions and is associated with certain genotypic characteristics. Here, we show that glucose and sodium chloride (NaCl) supplementation of culture media, a common practice in studies of biofilms , influences both biofilm formation by 40 clinical isolates (methicillin-resistant and methicillin-sensitive ) and causes variations in biofilm quantification.

Role of Phenol-Soluble Modulins in Staphylococcus epidermidis Biofilm Formation and Infection of Indwelling Medical Devices.

Phenol-soluble modulins (PSMs) are amphipathic, alpha-helical peptides that are secreted by staphylococci in high amounts in a quorum-sensing-controlled fashion. Studies performed predominantly in Staphylococcus aureus showed that PSMs structure biofilms, which results in reduced biofilm mass, while it has also been reported that S. aureus PSMs stabilize biofilms due to amyloid formation.

Do amyloid structures formed by Staphylococcus aureus phenol-soluble modulins have a biological function?

Phenol-soluble modulins (PSMs) are alpha-helical, amphipathic peptides that have multiple functions in staphylococcal physiology and virulence. Recent research has suggested that PSMs form amyloid fibrils and amyloids are involved in PSM-mediated phenotypes such as cytolysis and biofilm stability. While we observed PSM amyloid formation using electron microscopy and dye assays, there were no apparent differences in the production of extracellular fibrous material between a PSM-deficient strain and the isogenic wild-type strain.

Phenol-Soluble Modulin Toxins of .

Coagulase-negative staphylococci (CoNS) are important nosocomial pathogens and the leading cause of sepsis. The second most frequently implicated species, after , is . However, we have a significant lack of knowledge about what causes virulence of , as virulence factors of this pathogen have remained virtually unexplored.