Epidermidis Strains Research Articles

Dalbavancin-resistant Staphylococcus epidermidis in vivo selection following a prosthetic joint infection: phenotypic and genomic characterization.

Dalbavancin is a lipoglycopeptide antibiotic with a wide spectrum of activity against Gram-positive bacteria, including MDR isolates. Its pharmacokinetic properties and administration patterns could be useful for the treatment of bone and joint infections, especially prosthetic joint infections (PJIs). We report the case of an 80-year-old man who experienced an acute periprosthetic joint infection of his right total knee arthroplasty (TKA). A DAIR procedure was done with tissue sampling, which allowed identification of a linezolid-resistant MDR S. epidermidis (LR-MDRSE) strain. The patient was then treated with dalbavancin (four injections). We studied the phenotypic and genomic evolution of the strains and plasma through concentrations of dalbavancin at different points in time. After four injections (1500 mg IV) of dalbavancin over a 6 month period, the dalbavancin MIC increased 4-fold. Calculated fAUC0-24/MIC ratios were 945, 1239 and 766.5, respectively, at Days 49, 71 and 106, assuming an MIC of 0.032 mg/L. The PFGE dendrogram revealed 97% similarity among all the isolates. These results suggest acquisition by the S. epidermidis strain of dalbavancin resistance when the patient underwent dalbavancin treatment. A 4-amino-acid deletion in the walK gene coinciding with the emergence of phenotypic resistance was revealed by WGS without any other relevant indels. Despite dalbavancin treatment with pharmacokinetic management, emerging dalbavancin resistance in S. epidermidis was observed, resulting in treatment failure. This outcome led to a prosthesis revision and long-term suppressive antibiotic therapy, with no recurrence of PJI after an 18 month follow-up.

Potential of training of anti-Staphylococcus aureus therapeutic phages against Staphylococcus epidermidis multidrug-resistant isolates is restricted by inter- and intra-sequence type specificity.

Phage therapy appears to be a promising approach to tackle multidrug-resistant bacteria, including staphylococci. However, most anti-staphylococcal phages have been characterized in Staphylococcus aureus, while a limited number of studies investigated phage activity against S. epidermidis. We studied the potential of phage training to extend the host range of two types of anti-S. aureus phages against S. epidermidis isolates. The Appelmans protocol was applied to a mixture of Kayvirus and a mixture of Silviavirus phages repeatedly exposed to seven S. epidermidis strains representative of nosocomial-associated sequence types (ST), including the world-wide disseminated ST2. We observed increased activity only for the Kayvirus mixture against two of these strains (ST2 or ST35). Phage subpopulations isolated from the training mixture using these two strains (five/strain) exhibited different evolved phenotypes, active only against their isolation strain or strains of the same ST. Of note, 16/47 ST2 strains were susceptible to one of the groups of trained phages. A comparative genomic analysis of ancestral and trained phage genomes, conducted to identify potential bacterial determinants of such specific activity, found numerous recombination events between two of the three ancestors. However, a small number of trained phage genes had nucleotide sequence modifications impacting the corresponding protein compared to ancestral phages, two to four of them per phage genome being specific of each group of phage subpopulations exhibiting different host range. The results suggest that anti-S. aureus phages can be adapted to S. epidermidis isolates but with inter- and intra-ST specificity.ImportanceS. epidermidis is increasingly recognized as a threat for public health. Its clinical importance is notably related to multidrug resistance. Phage therapy is one of the most promising alternative therapeutic strategies to antibiotics. Nonetheless, only very few phages active against this bacterial species have been described. In the present study, we showed that phage training can be used to extend the host range of polyvalent Kayvirus phages within the Staphylococcus genera to include S. epidermidis species. In the context of rapid development of phage therapy, in vitro forced adaptation of previously characterized phages could be an appealing alternative to fastidious repeated isolation of new phages to improve the therapeutic potential of a phage collection.

Complete genome sequence of three Staphylococcus epidermidis strains isolated from patients with skin diseases in Japan.

Staphylococcus epidermidis is a member of the human skin microbiota as a commensal organism but could be an important opportunistic pathogen for immunocompromised individuals. Here, we report the complete genome sequence of three S. epidermidis strains isolated from patients with skin diseases.

Analysis of the broad-spectrum potential of nitric oxide for antibacterial activity against clinically isolated drug-resistant bacteria.

The development of drug-resistant microorganisms is taking a heavy toll on the biomedical world. Clinical infections are costly and becoming increasingly dangerous as bacteria that once responded to standard antibiotic treatment are developing resistance mechanisms that require innovative treatment strategies. Nitric oxide (NO) is a gaseous molecule produced endogenously that has shown potent antibacterial capabilities in numerous research studies. Its multimechanistic antibacterial methods prevent the development of resistance and have shown potential as an alternative to antibiotics. However, there has yet to be a direct comparison study evaluating the antibacterial properties of NO against antibiotic susceptible and antibiotic-resistant clinically isolated bacterial strains. Herein, standardized lab and clinically isolated drug-resistant bacterial strains are compared side-by-side for growth and viability following treatment with NO released from S-nitrosoglutathione (GSNO), an NO donor molecule. Evaluation of growth kinetics revealed complete killing of E. coli lab and clinical strains at 17.5 mM GSNO, though 15 mM displayed >50% killing and significantly reduced metabolic activity, with greater dose dependence for membrane permeability. Clinical P. aeruginosa showed greater susceptibility to GSNO during growth curve studies, but metabolic activity and membrane permeability demonstrated similar effects for 12.5 mM GSNO treatment of lab and clinical strains. MRSA lab and clinical strains exhibited total killing at 17.5 mM treatment, though metabolic activity was decreased, and membrane permeation began at 12.5 mM for both strains. Lastly, both S. epidermidis strains were killed by 15 mM GSNO, with sensitivities in metabolic activity and membrane permeability at 12.5 mM GSNO. The mirrored antibacterial effects seen by the lab and clinical strains of two Gram-negative and two Gram-positive bacteria reveal the translational success of NO as an antibacterial therapy and potential alternative to standard antibiotic treatment.

Completed genome and emergence scenario of the multidrug-resistant nosocomial pathogen Staphylococcus epidermidis ST215

BackgroundA multidrug-resistant lineage of Staphylococcus epidermidis named ST215 is a common cause of prosthetic joint infections and other deep surgical site infections in Northern Europe, but is not present elsewhere. The increasing resistance among S. epidermidis strains is a global concern. We used whole-genome sequencing to characterize ST215 from healthcare settings.ResultsWe completed the genome of a ST215 isolate from a Swedish hospital using short and long reads, resulting in a circular 2,676,787 bp chromosome and a 2,326 bp plasmid. The new ST215 genome was placed in phylogenetic context using 1,361 finished public S. epidermidis reference genomes. We generated 10 additional short-read ST215 genomes and 11 short-read genomes of ST2, which is another common multidrug-resistant lineage at the same hospital. We studied recombination’s role in the evolution of ST2 and ST215, and found multiple recombination events averaging 30–50 kb. By comparing the results of antimicrobial susceptibility testing for 31 antimicrobial drugs with the genome content encoding antimicrobial resistance in the ST215 and ST2 isolates, we found highly similar resistance traits between the isolates, with 22 resistance genes being shared between all the ST215 and ST2 genomes. The ST215 genome contained 29 genes that were historically identified as virulence genes of S. epidermidis ST2. We established that in the nucleotide sequence stretches identified as recombination events, virulence genes were overrepresented in ST215, while antibiotic resistance genes were overrepresented in ST2.ConclusionsThis study features the extensive antibiotic resistance and virulence gene content in ST215 genomes. ST215 and ST2 lineages have similarly evolved, acquiring resistance and virulence through genomic recombination. The results highlight the threat of new multidrug-resistant S. epidermidis lineages emerging in healthcare settings.

Preclinical development of ATR04-484, an auxotrophic strain of Staphylococcus epidermidis, for the topical treatment of epidermal growth factor receptor (EGFR) inhibitor-induced dermal toxicity.

e24074 Background: Agents targeting the EGFR-mediated signaling pathway are commonly used for the treatment of advanced lung, pancreatic, colorectal, and head and neck cancers. Significant dermal toxicities, which occur in up to 90% of patients treated with EGFR inhibitors (EGFRis) and other therapies inhibiting downstream signaling pathways, may be disruptive to a patient’s quality of life and adherence to therapy. Inhibition of the EGFR pathway may suppress host defenses and lead to opportunistic pathogenic colonization or infection. EGFRi-induced dermal toxicity is associated with elevated levels of Staphylococcus aureus and IL-36γ. ATR04-484 is a topical ointment containing S. epidermidis strain SE484, isolated from a healthy human volunteer that was selected for its ability to inhibit S. aureus and IL-36γ . Methods: Reconstructed human epidermis (RHE) and ex vivo pig skin were used to measure the effect of ATR04-484 on S. aureus in therapeutic and prophylactic settings with S. aureus added prior to or after ATR04-484, respectively. To evaluate the anti-inflammatory effects of ATR04-484, IL-36γ levels were measured on untreated RHE and RHE treated with erlotinib alone or in combination with ATR04-484. 104 colony-forming units (CFU) of methicillin-resistant (MRSA) or methicillin-sensitive (MSSA) S. aureus were used. Toxicology was assessed by measuring cell viability in three in vitro toxicology assays: the eye irritant potential was tested on 3D reconstituted human cornea-like epithelium (RhCE), the skin irritant potential of the strain in the ointment was assessed on 3D RHE, and the skin corrosive potential was evaluated on RHE. Results: ATR04-484 comparably inhibited growth of both MRSA and MSSA in therapeutic and prophylactic settings. In a therapeutic setting, ATR04-484 inhibited MRSA growth by 1 log (90%) compared to untreated MRSA in both RHE and pig skin. In a prophylactic setting, ATR04-484 inhibited MRSA growth by approximately 5 logs on RHE and 2 logs on pig skin. Additionally, application of ATR04-484 reduced IL-36γ to a level comparable to untreated RHE. The effect was dose-dependent; application of 109CFU/cm2 of ATR04-484 showed more potent IL-36γ reduction compared to 108 CFU/cm2. The three toxicology assays indicate that ATR04-484 does not cause irritation or corrosion. Conclusions: In these preclinical studies, ATR-04-484 showed a promising preclinical profile for the treatment of EGFRi-induced dermal toxicity by significantly reducing S. aureus growth, completely ameliorating IL-36γ levels, and showing no safety concerns.

Antibacterial and Antibiofilm Potential of Bacterial Cellulose Hydrogel Containing Vancomycin against Multidrug-Resistant Staphylococcus aureus and Staphylococcus epidermidis.

The present study aimed to evaluate the in vitro antibacterial and antibiofilm activity of bacterial cellulose hydrogel produced by Zoogloea sp. (HYDROGEL) containing vancomycin (VAN) against bacterial strains that cause wound infections, such as multidrug-resistant (MDR) Staphylococcus aureus and Staphylococcus epidermidis. Initially, HYDROGEL was obtained from sugar cane molasses, and scanning electron microscopy (SEM) was performed to determine morphological characteristics. Then, VAN was incorporated into HYDROGEL (VAN-HYDROGEL). The antibacterial activity of VAN, HYDROGEL, and VAN-HYDROGEL was assessed using the broth microdilution method to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) against methicillin-sensitive S. aureus (MSSA) ATCC 25923, methicillin-resistant S. aureus (MRSA) ATCC 33591, S. epidermidis INCQS 00016 (ATCC 12228), five clinical isolates of MRSA, and nine clinical isolates of methicillin-resistant S. epidermidis, following the Clinical and Laboratory Standards Institute (CLSI) guidelines. Additionally, the antibacterial activity of VAN, HYDROGEL, and VAN-HYDROGEL was studied using the time-kill assay. Subsequently, the antibiofilm activity of VAN, HYDROGEL, and VAN-HYDROGEL was evaluated using crystal violet and Congo red methods, as well as SEM analysis. VAN and VAN-HYDROGEL showed bacteriostatic and bactericidal activity against MRSA and methicillin-resistant S. epidermidis strains. HYDROGEL did not show any antibacterial activity. Analysis of the time-kill assay indicated that HYDROGEL maintained the antibacterial efficacy of VAN, highlighting its efficiency as a promising carrier. Regarding antibiofilm activity, VAN and HYDROGEL inhibited biofilm formation but did not demonstrate biofilm eradication activity against methicillin-resistant S. aureus and S. epidermidis strains. However, it was observed that the biofilm eradication potential of VAN was enhanced after incorporation into HYDROGEL, a result also proven through images obtained by SEM. From the methods carried out in this study, it was possible to observe that HYDROGEL preserved the antibacterial activity of vancomycin, aside from exhibiting antibiofilm activity and enhancing the antibiofilm effect of VAN. In conclusion, this study demonstrated the potential of HYDROGEL as a candidate and/or vehicle for antibiotics against MDR bacteria that cause wound infections.

Comparative Study of Staphylococcus epidermidis Virulence Profiles in an animal Model of Endophthalmitis

Introduction: Gram-positive staphylococci are responsible for over 90% of cases of postoperative infectious endophthalmitis, with Staphylococcus epidermidis accounting for approximately 70% of isolated microorganisms. Objective: To evaluate the relationship between S. epidermidis virulence and severity of endophthalmitis in an animal model. Methodology: New Zealand albino rabbits were divided into two groups and administered 100 colony-forming units of S. epidermidis strains. In the virulent group, four rabbits received a multi-antibiotic resistant, mecA, ica, and atlE gene carrying S. epidermidis strain, from a patient´s conjuntival microbiota and three a biofilm-forming S. epidermidis ATCC 35984. In the non-virulent group, five rabbits were inoculated with a strain sensitive to all tested antibiotics and lacking mecA, ica, and atlE genes, also from a patient and three rabbits received the non-producer biofilm S. epidermidis ATCC 29122. Clinical and ultrasound examinations were conducted every three hours until endophthalmitis symptoms appeared, followed by daily clinical assessments. Histological evaluations were performed 15 days post-inoculation. Results: The less virulent group displayed milder inflammation and reduced intraocular damage in comparison to the more virulent group based on clinical and ultrasound observations. Nevertheless, histopathological analysis revealed similar inflammation in all groups, 15 days post-inoculation. Discussion: Less virulent S. epidermidis strains induced less severe inflammation as observed through clinical and ultrasound assessments. However, long-term histopathological assessments showed effects comparable to those seen with the more virulent strain.

Deletion of codY impairs Staphylococcus epidermidis biofilm formation, generation of viable but non-culturable cells and stimulates cytokine production in human macrophages.

Introduction. Staphylococcus epidermidis biofilms are one of the major causes of bloodstream infections related to the use of medical devices. The diagnosis of these infections is challenging, delaying their treatment and resulting in increased morbidity and mortality rates. As such, it is urgent to characterize the mechanisms employed by this bacterium to endure antibiotic treatments and the response of the host immune system, to develop more effective therapeutic strategies. In several bacterial species, the gene codY was shown to encode a protein that regulates the expression of genes involved in biofilm formation and immune evasion. Additionally, in a previous study, our group generated evidence indicating that codY is involved in the emergence of viable but non-culturable (VBNC) cells in S. epidermidis.Gap statement/Hypothesis. As such, we hypothesized that the gene codY has have an important role in this bacterium virulence.Aim. This study aimed to assess, for the first time, the impact of the deletion of the gene codY in S. epidermidis virulence, namely, in antibiotic susceptibility, biofilm formation, VBNC state emergence and in vitro host immune system response.Methodology. Using an allelic replacement strategy, we constructed and then characterized an S. epidermidis strain lacking codY, in regards to biofilm and VBNC cell formation, susceptibility to antibiotics as well as their role in the interaction with human blood and plasma. Additionally, we investigate whether the codY gene can impact the activation of innate immune cells by evaluating the production of both pro- and anti-inflammatory cytokines by THP-1 macrophages.Results. We demonstrated that the deletion of the gene codY resulted in biofilms with less c.f.u. counts and fewer VBNC cells. Furthermore, we show that although WT and mutant cells were similarly internalized in vitro by human macrophages, a stronger cytokine response was elicited by the mutant in a toll-like receptor 4-dependent manner.Conclusion. Our results indicate that codY contributes to S. epidermidis virulence, which in turn may have an impact on our ability to manage the biofilm-associated infections caused by this bacterium.

Encapsulation of propolis extracted with methylal in the chitosan nanoparticles and its antibacterial and cell cytotoxicity studies

In this study we develop novel type of antibacterial chitosan-propolis NPs to improve theantimicrobial activity against various pathogens. To this aim, we primarily extracted propolis with methylal and ethanol as green solvents and its encapsulation with chitosan NPs. The developed propolis loaded chitosan NPs indicated antimicrobial and anti-biofilm properties against various gram positive and negative. FTIR revealed the successful encapsulation of the propolis extract with Ethanol (PE) and Methylal (PM) into the chitosan nano career matrix. HPLC and GC-MASS also confirmed the presence of flavonoids and phenols compounds of propolis extracted with both solvents. In addition, we confirmed the total phenolic and flavonoid compounds in propolis by calorimetric method of Folin–Ciocalteu and aluminum trichloride complex formation assays, respectively. PE-CH and PM-CH were optimized regarding physicochemical properties such as particle size, zeta potential, and poly dispersity index (PDI) index. DLS and SEM micrographs confirmed a spherical morphology in a range of 360–420 nm with Z potential values of 30–48 mV and PDI of 0.105–0.166 for PE-CH and PM-CH, respectively. The encapsulation efficiency was evaluated using colorimetric analysis, with median values ranging from 90 to 92%. The MIC values within the range of 2 to 230 µg/ml and MBC values between 3 to 346 μg/ml against both gram-positive and negative bacteria. While both PE and PM showed a significant reduction in the number of E. coli, S. aureus, and S. epidermidis, the use of PE-CH and PM-CH led to a statistically significant and greater reduction in number of E. coli, S. aureus, and S. epidermidis strains on the biofilm, pre-formed biofilm and planktonic phases. Besides, the DPPH assay showed significant antioxidant activity for these NPs within the range of 36 to 92%. MTT assay for MHFB-1, HFF, L929, MDF, and MCF-7 cells exhibited statistically significant differences in each other that show the IC50 between 60–160 µg/ml for normal cells and 20 for cancer cells. Finally the present study indicated that both PM and PM-CH greater than PE and PE-CH in which contain high flavonoid and phenolic contents with a high antioxidation potential antioxidant properties, which could be beneficial for cell proliferation and antibiotic and anticancer applications.

Comparative virulome analysis of four Staphylococcus epidermidis strains from human skin and platelet concentrates using whole genome sequencing.

Staphylococcus epidermidis is one of the predominant bacterial contaminants in platelet concentrates (PCs), a blood component used to treat bleeding disorders. PCs are a unique niche that triggers biofilm formation, the main pathomechanism of S. epidermidis infections. We performed whole genome sequencing of four S. epidermidis strains isolated from skin of healthy human volunteers (AZ22 and AZ39) and contaminated PCs (ST10002 and ST11003) to unravel phylogenetic relationships and decipher virulence mechanisms compared to 24 complete S. epidermidis genomes in GenBank. AZ39 and ST11003 formed a separate unique lineage with strains 14.1 .R1 and SE95, while AZ22 formed a cluster with 1457 and ST10002 closely grouped with FDAAGOS_161. The four isolates were assigned to sequence types ST1175, ST1174, ST73 and ST16, respectively. All four genomes exhibited biofilm-associated genes ebh, ebp, sdrG, sdrH and atl. Additionally, AZ22 had sdrF and aap, whereas ST10002 had aap and icaABCDR. Notably, AZ39 possesses truncated ebh and sdrG and harbours a toxin-encoding gene. All isolates carry multiple antibiotic resistance genes conferring resistance to fosfomycin (fosB), β-lactams (blaZ) and fluoroquinolones (norA). This study reveales a unique lineage for S. epidermidis and provides insight into the genetic basis of virulence and antibiotic resistance in transfusion-associated S. epidermidis strains.

Comparison of the in vitro activities of delafloxacin and comparators against Staphylococcus epidermidis clinical strains involved in osteoarticular infections: a CRIOGO multicentre retrospective study.

Staphylococcus epidermidis bone and joint infections (BJIs) on material are often difficult to treat. The activity of delafloxacin has not yet been studied on S. epidermidis in this context. The aim of this study was to assess its in vitro activity compared with other fluoroquinolones, against a large collection of S. epidermidis clinical strains. We selected 538 S. epidermidis strains isolated between January 2015 and February 2023 from six French teaching hospitals. One hundred and fifty-two strains were ofloxacin susceptible and 386 were ofloxacin resistant. Identifications were performed by MS and MICs were determined using gradient concentration strips for ofloxacin, levofloxacin, moxifloxacin and delafloxacin. Ofloxacin-susceptible strains were susceptible to all fluoroquinolones. Resistant strains had higher MICs of all fluoroquinolones. Strains resistant to ofloxacin (89.1%) still showed susceptibility to delafloxacin when using the Staphylococcus aureus 2021 CA-SFM/EUCAST threshold of 0.25 mg/L. In contrast, only 3.9% of the ofloxacin-resistant strains remained susceptible to delafloxacin with the 0.016 mg/L S. aureus breakpoint according to CA-SFM/EUCAST guidelines in 2022. The MIC50 was 0.094 mg/L and the MIC90 was 0.38 mg/L. We showed low delafloxacin MICs for ofloxacin-susceptible S. epidermidis strains and a double population for ofloxacin-resistant strains. Despite the absence of breakpoints for S. epidermidis, delafloxacin may be an option for the treatment of complex BJI, including strains with MICs of ≤0.094 mg/L, leading to 64% susceptibility. This study underlines the importance for determining specific S. epidermidis delafloxacin breakpoints for the management of BJI on material.

Antibacterial Effect of Eight Essential Oils against Bacteria Implicated in Bovine Mastitis and Characterization of Primary Action Mode of Thymus capitatus Essential Oil.

During the current investigation, eight essential oils (EOs) were tested for their antimicrobial activity against six species, belonging to the genus of staphylococcus, multi-resistant to antibiotics (S. epidermidis, S. cohni, S. wareneri, S. scuiri, S. chromogenes, S. pasteuri), three methicillin-resistant Staphylococcus aureus strains (MRSA) and two strains of Escherichia coli, producing extended-spectrum β-lactamase (ESBL) responsible for bovine mastitis. Our results indicated that the antimicrobial activities of eight EOs varied significantly among the types of EOs and bacterial species. Thymus capitatus and Trachyspermum ammi EOs display important antibacterial activity against all tested strains, with the inhibition zone diameters situated between 20 and 45 mm, while EOs of Artemisia absinthium, Eucalyptus globulus, Eucalyptus camaldulensis, Myrtus communis and Mentha pulegium exerted an intermediate activity. For Cymbopogon citratus, this effect depends on bacteria species. In fact, an important effect was observed against S. warneri, S. epidermidis, S. cohenii, S. pasteuri and MRSA (EC 39+) strains. In addition, the important lytic effect was observed against MRSA strains, showing that Gram-positive bacteria were more sensitive to T. capitatus EO than Gram-negative ones. Concerning the characterization of the mode action of T. capitatus, experiments of kill-time, bacteriolytic, loss of salt tolerance and loss of cytoplasmic material showed that the used EO was able to destroy cell walls and membranes followed by the loss of vital intracellular materials. In addition, it inhibits the normal synthesis of DNA, causing the bacterial death of E. coli and MRSA strains. This study shows the potential of using of EOs, particularly T. capitaus, to inhibit the growth of Gram-positive and Gram-negative bacteria multi-resistant to antibiotics causing bovine mastitis.

Persistence and evolution of linezolid- and methicillin-resistant Staphylococcus epidermidis ST2 and ST5 clones in an Italian hospital

Staphylococcus epidermidis is a member of the human skin microbiome. However, in recent decades, multidrug-resistant and hospital-adapted S. epidermidis clones are increasingly involved in severe human infections associated with medical devices and in immunocompromised patients. In 2016, we reported that a linezolid- and methicillin-resistant S. epidermidis ST2 clone, bearing the G2576T mutation, was endemic in an Italian hospital since 2004. This study aimed to retrospectively analyse 34 linezolid- and methicillin-resistant S. epidermidis (LR-MRSE) strains collected from 2018 to 2021 from the same hospital. LR-MRSE were typed by Pulsed-Field Gel Electrophoresis and multilocus sequence typing and screened for transferable linezolid resistance genes. Representative LR-MRSE were subjected to whole-genome sequencing (WGS) and their resistomes, including the presence of ribosomal mechanisms of linezolid resistance and of rpoB gene mutations conferring rifampin resistance, were investigated. ST2 lineage was still prevalent (19/34; 55.9%), but, over time, ST5 clone has been widespread too (15/34; 44.1%). Thirteen of the 34 isolates (38.2%) were positive for the cfr gene. Whole-genome sequencing analysis of relevant LR-MRSE displayed complex resistomes for the presence of several acquired antibiotic resistance genes, including the SCCmec type III (3A) and SCCmec type IV (2B) in ST2 and ST5 isolates, respectively. Bioinformatics and polymerase chain reaction (PCR) mapping also showed a plasmid-location of the cfr gene and the occurrence of previously undetected mutations in L3 (ST2 lineage) and L4 (ST3 lineage) ribosomal proteins and substitutions in the rpoB gene. The occurrence of LR-MRSE should be carefully monitored in order to prevent the spread of this difficult-to-treat pathogen and to preserve the efficacy of linezolid.

Improving Activity of New Arylurea Agents against Multidrug-Resistant and Biofilm-Producing Staphylococcus epidermidis.

Multidrug-resistant (MDR) strains of Staphylococcus epidermidis (S. epidermidis), prevalent in hospital environments, contribute to increased morbidity and mortality, especially among newborns, posing a critical concern for neonatal sepsis. In response to the pressing demand for novel antibacterial therapies, we present findings from synthetic chemistry and structure-activity relationship studies focused on arylsulfonamide/arylurea derivatives of aryloxy[1-(thien-2-yl)propyl]piperidines. Through bioisosteric replacement of the sulfonamide fragment with a urea moiety, compound 25 was identified, demonstrating potent bacteriostatic activity against clinical multidrug-resistant S. epidermidis strains (MIC50 and MIC90 = 1.6 and 3.125 μg/mL). Importantly, it showed activity against linezolid-resistant strains and exhibited selectivity over mammalian cells. Compound 25 displayed antibiofilm-forming properties against clinical S. epidermidis strains and demonstrated the capacity to eliminate existing biofilm layers. Additionally, it induced complete depolarization of the bacterial membrane in clinical S. epidermidis strains. In light of these findings, targeting bacterial cell membranes with compound 25 emerges as a promising strategy in the fight against multidrug-resistant S. epidermidis strains.

NOVEL ANTIMICROBIAL COATING ON TITANIUM WITH STABLE NON-ANTIBIOTIC QUATERNARY AMMONIUM COMPOUNDS TO PREVENT IMPLANT-ASSOCIATED INFECTION

Infection of implanted medical devices (biomaterials), like titanium orthopaedic implants, can have disastrous consequences, including removal of the device. These so-called biomaterial-associated infections (BAI) are mainly caused by Staphylococcus aureus and Staphylococcus epidermidis. To prevent biofilm formation using a non-antibiotic based strategy, we aimed to develop a novel permanently fixed antimicrobial coating for titanium devices based on stable immobilized quaternary ammonium compounds (QACs).Medical grade titanium implants were dip-coated in subsequent solutions of hyperbranched polymer, polyethyleneimine and 10 mM sodium iodide, and ethanol. The QAC-coating was characterized using water contact angle measurements, scanning electron microscopy, FTIR, AFM and XPS. The antimicrobial activity of the coating was evaluated against S. aureus strain JAR060131 and S. epidermidis strain ATCC 12228 using the JIS Z 2801:2000 surface microbicidal assay. Lastly, we assessed the in vivo antimicrobial activity in a mouse subcutaneous implant infection model with S. aureus administered locally on the QAC-coated implants prior to implantation to mimic contamination during surgery.Detailed material characterization of the titanium samples showed the presence of a homogenous and stable coating layer at the titanium surface. Moreover, the coating successfully killed S. aureus and S. epidermidis in vitro. The QAC-coating strongly reduced S. aureus colonization of the implant surface as well as of the surrounding tissue, with no apparent macroscopic signs of toxicity or inflammation in the peri-implant tissue at 1 and 4 days after implantation.An antimicrobial coating with stable quaternary ammonium compounds on titanium has been developed which holds promise to prevent BAI. Non-antibiotic-based antimicrobial coatings have great significance in guiding the design of novel antimicrobial coatings in the present, post-antibiotic era.Acknowledgements: This research was financially supported by the Health∼Holland/LSH-TKI call 2021–2022, project 25687, NACQAC: ‘Novel antimicrobial coatings with stable non-antibiotic Quaternary Ammonium Compounds and photosensitizer technology'.

Prevalence and anti-microbial resistance of Staphylococcus spp. isolated from the environment and veterinary personnel in a Spanish veterinary teaching hospital.

Methicillin-resistant Staphylococcus (MRS) bacteria, including methicillin-resistant S. aureus and methicillin-resistant S. pseudintermedius (MRSP), pose a significant threat in veterinary medicine, given their potential for zoonotic transmission and their implications for companion animals and humans' health. This study aimed to assess the prevalence of MRS and anti-microbial resistance patterns at a university clinical hospital in Madrid, Spain. Samples were collected from both the environment and hospital staff at Veterinary Clinical Hospital of Alfonso X el Sabio University. Anti-microbial susceptibility assays, molecular detection of mecA gene and genetic relationships among the identified bacterial strains were performed. The study revealed an MRS prevalence of 1.50% in environmental samples, with MRSP accounting for 0.75% of the cases. Genetically related MRSP strains were found in different hospital areas. Among hospital staff, there was a MRS prevalence of 14.03%, including S. pseudintermedius and S. epidermidis strains. Antibiogram tests revealed multi-drug resistance among MRSP strains. Additionally, methicillin-resistant coagulase-negative staphylococci were isolated, suggesting potential cross-species transmission. This study underscores the presence of MRS in a veterinary clinical hospital, highlighting the significance of infection control through the implementation of protective measures, stringent hygiene practices among personnel and in the environment and responsible use of antibiotics. Further research is necessary to assess MRS incidence in animal patients and explore geographical variations, enhancing our understanding of MRS in veterinary medicine and addressing its challenges.

Sulphated TiO2 Reduced by Ammonia and Hydrogen as an Excellent Photocatalyst for Bacteria Inactivation.

This study presents a relatively low-cost method for modifying TiO2-based materials for photocatalytic bacterial inactivation. The photocatalytic inactivation of Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus epidermidis) bacteria using modified sulphated TiO2 was studied. The modification focused on the reduction of TiO2 by ammonia agents and hydrogen at 400-450 °C. The results showed a high impact of sulphate species on the inactivation of E. coli. The presence of these species generated acid sites on TiO2, which shifted the pH of the reacted titania slurry solution to lower values, around 4.6. At such a low pH, TiO2 was positively charged. The ammonia solution caused the removal of sulphate species from TiO2. On the other hand, hydrogen and ammonia molecules accelerated the removal of sulphur species from TiO2, as did heating it to 450 °C. Total inactivation of E. coli was obtained within 30 min of simulated solar light irradiation on TiO2 heat-treated at 400 °C in an atmosphere of Ar or NH3. The S. epidermidis strain was more resistant to photocatalytic oxidation. The contact of these bacteria with the active titania surface is important, but a higher oxidation force is necessary to destroy their cell membrane walls because of their thicker cell wall than E. coli. Therefore, the ability of a photocatalyst to produce ROS (reactive oxidative species) will determine its ability to inactivate S. epidermidis. An additional advantage of the studies presented is the inactivation of bacteria after a relatively short irradiation time (30 min), which does not often happen with photocatalysts not modified with noble metals. The modification methods presented represent a robust and inexpensive alternative to photocatalytic inactivation of bacteria.

Staphylococcus epidermidis joint isolates: Whole-genome sequencing demonstrates evidence of hospital transmission and common antimicrobial resistance.

We investigated genetic, epidemiologic, and environmental factors contributing to positive Staphylococcus epidermidis joint cultures. Retrospective cohort study with whole-genome sequencing (WGS). We identified S. epidermidis isolates from hip or knee cultures in patients with 1 or more prior corresponding intra-articular procedure at our hospital. WGS and single-nucleotide polymorphism-based clonality analyses were performed, including species identification, in silico multilocus sequence typing (MLST), phylogenomic analysis, and genotypic assessment of the prevalence of specific antibiotic resistance and virulence genes. Epidemiologic review was performed to compare cluster and noncluster cases. In total, 60 phenotypically distinct S. epidermidis isolates were identified. After removal of duplicates and impure samples, 48 isolates were used for the phylogenomic analysis, and 45 (93.7%) isolates were included in the clonality analysis. Notably, 5 S. epidermidis strains (10.4%) showed phenotypic susceptibility to oxacillin yet harbored mecA, and 3 (6.2%) strains showed phenotypic resistance despite not having mecA. Smr was found in all isolates, and mupA positivity was not observed. We also identified 6 clonal clusters from the clonality analysis, which accounted for 14 (31.1%) of the 45 S. epidermidis isolates. Our epidemiologic investigation revealed ties to common aspirations or operative procedures, although no specific common source was identified. Most S. epidermidis isolates from clinical joint samples are diverse in origin, but we identified an important subset of 31.1% that belonged to subclinical healthcare-associated clusters. Clusters appeared to resolve spontaneously over time, suggesting the benefit of routine hospital infection control and disinfection practices.

Attenuated inflammatory response in infant mice with Staphylococcus epidermidis CNS catheter infection

Children under one year of age are consistently found to be at the highest risk for shunt infection as a complication of hydrocephalus treatment, and repeated infections in the same patient are common. The mechanisms responsible for the increase in infant infection are not known. Our laboratory adapted our existing mouse model of Staphylococcus epidermidis central nervous system (CNS) catheter infection to characterize infection in infant mice as a foundation of on-going studies to determine the mechanisms of increased morbidity in infant shunt infections. The well-established model of S. epidermidis biofilm infection in the CNS was adapted to generate infection in 14-day old C57BL/6 mice. The catheter preparation was identical to the adult model, in which silicone catheters are pre-coated with a clinically derived biofilm-forming strain of S. epidermidis strain 1457) to introduce S. epidermidis into the brain. The catheters are stereotactically implanted into the lateral left ventricle. Bacterial titers as well as cytokine and chemokine levels were measured at days 1, 3, and 5 in mice implanted with sterile and S. epidermidis-coated catheters. Cultures demonstrated both catheter-associated and parenchymal infection through day 5 post-implantation. In contrast to prior adult models of CNS catheter infection, however, the catheter-associated bacterial burdens were less than or equal to parenchymal bacterial burdens. There was no significant difference between the chemokine and cytokine levels in the brain tissues of pups with sterile versus S. epidermidis infected catheters for any of the analytes tested. The infant model of S. epidermidis CNS catheter infection is characterized by both a greater degree of parenchymal spread of bacteria and the absence of the elevated pro-inflammatory cytokines previously observed in adult mice with this infection. The attenuated inflammatory response may contribute to the increased infection risk observed in this population.