Epidermidis Strains Research Articles

An invasive marker Staphylococcus epidermidis surface protein I (SesI) harboured by a ST239 methicillin-resistant Staphylococcus aureus.

Recently, the virulence factor sasX was described on the mobile genetic element φSPβ prophage in a ST239-SCCmecIII methicillin-resistant Staphylococcus aureus (MRSA) clone. The aim of this study was to identify sesI, an sasX homologue, in an MRSA ST239 strain. MRSA strain VB1490 was isolated from a patient with MRSA bacteraemia in India. Staphylococcal cassette chromosomemec (SCCmec) typing and whole-genome shotgun sequencing were performed. Phylogenetic analysis of VB1490 and ST239 reference genomes from the NCBI database was performed. Amplification and sequencing of the sasX gene was performed to establish allele homology. The sasX gene identified in isolate VB1490 was more similar to the sesI gene of Staphylococcus epidermidis RP62A than the sasX gene of ST239 MRSA strain. Whole-genome analysis revealed the presence of the sasX gene on a φSPβ-like prophage that exhibited high sequence identity to that of S. epidermidis strain RP62A. These finding suggests the dissemination of the invasion-determining virulence factorsesI from S. epidermidis to a ST239 MRSA strain.

Draft genome sequences of three clinical isolates of teicoplanin-resistant Staphylococcus epidermidis from patients without prior exposure to glycopeptide antibiotics.

The aim of this study was to analyse the DNA sequences of three teicoplanin-resistant Staphylococcus epidermidis isolates collected from patients not previously treated with glycopeptide antibiotics. The minimum inhibitory concentrations (MICs) of 12 antibiotics, including teicoplanin and vancomycin, were determined by the broth microdilution method. Genomic DNA was isolated, was sequenced by HiSeqX paired-end sequencing and was assembled into draft genome sequences using MyPro pipeline. Analysis of the draft genome sequences demonstrated that the teicoplanin-resistant S. epidermidis isolates belonged to multilocus sequence typing (MLST) sequence types ST5 and ST87 and encoded multiple antimicrobial resistance genes, including the methicillin resistance gene mecA. This report highlights the risk of dissemination of S. epidermidis strains resistant to a wide range of clinically important antibiotics.

S. epidermidis strains from artisanal cheese made from unpasteurized milk in Poland - Genetic characterization of antimicrobial resistance and virulence determinants

In Poland artisanal cheese production is an important local economic activity. Artisanal cheese is usually produced using raw cow's milk, animal rennet and salt, without the addition of starter cultures. Coagulase negative staphylococci (CoNS) are often present in artisanal cheeses. Pathogenic potential of some CoNS species, especially S. epidermidis, suggests that they could correspond to emerging pathogens. The identified risk factors correspond to virulence, antibiotic resistance and biofilm formation. Therefore, we aimed to characterize S. epidermidis isolated along the artisanal raw milk production chain. Seventy artisanal cheeses samples from unpasteurized cow milk purchased in Podlasie and Warmia and Mazury region in Poland, were included in this study. A total of 26 S. epidermidis isolates were obtained. Most of them were antimicrobial resistant, such as to penicillin (84,6%), clindamycin (46,2%), tetracycline (42,3%), erythromycin (42,3%) and cefoxitin (26,9%). Only one isolate was susceptible to all antibiotics used in the study. All methicillin resistant S. epidermidis strains (26,9%) harbored mecA gene. Isolates, phenotypic resistant to tetracycline, harbored at least one tetracycline resistance determinant on which tet(M) was most frequent. Moreover, all tetracycline resistant strains harbored Tn916-Tn1545-like integrase family gene. In the erythromycin resistant isolates, the macrolide resistance genes ermC, ermB or msrA/B were present. Seven strains demonstrated a strong ability to form biofilm and moderate and weak biofilm was demonstrated by 4 strains, whereas 11 of S. epidermidis isolates were found to be unable to form a biofilm. All strains producing strong biofilm harbored the icaD gene which occurred independently or in combination with the icaA. Insertion element IS256, was identified in 15,4% of S. epidermidis strains, all of which were multidrug resistant. Arginine Catabolic Mobile Element (ACME) was identified in 13 of the 26 examined strains (50%). Most common was ACME type I (26,9%), followed by type III (15,4%) and type II (7,7%). Our data indicate that S. epidermidis are widely present in artisanal cheeses from raw whole cow milk in Poland. Many isolated strains containing more virulence factors and antibiotic resistant and carry mobile genetic elements which represent a potential source of resistance transmission to bacteria in humans.

Synthesis, docking and antibacterial studies of more potent amine and hydrazone rifamycin congeners than rifampicin

New rifamycin congeners (1-33) with incorporated amine and hydrazone substituents leading to lipophilic and/or basic nature and altered rigidity of modified C(3) arm were synthesized and structurally characterized in detail. NMR spectroscopic studies at different temperatures indicate two types of structures of rifamycin congeners that are realized in solution: zwitterionic and non-ionic forms in dependence of the basicity of modified C(3) arm. The presence of rifamycin congeners in these two possible forms has a significant impact on the physico-chemical parameters such as lipophilicity (clogP) and water solubility and different binding mode of the C(3) arm of antibiotic at RNAP binding pocket (molecular target) leading to different antibacterial potency. The highest antibacterial potency against S. aureus (including MRSA and MLSB strains) and S. epidermidis strains, even higher than reference rifampicin (Rif) and rifaximin (Rifx) antibiotics, was found for rifamycin congeners bearing at the C(3) arm relatively rigid and basic substituents (bipiperidine and guanidine groups). These modifications provide favorable docking mode and excellent water solubility resulting in high potency (MICs 0.0078 μg/mL what gives ∼ 8.5 nM), irrespective whether rifamycin congener is a tertiary amine (15) or hydrazone (29). In turn, for a higher antibacterial potency of rifamycin congeners against E. faecalis strain (MICs 0.5 μg/mL that is 0.6 μM) as compared to Rif and Rifx, the most crucial factors are: bulkiness and the lipophilic character of the end of the C(3) rebuilt arm.

Biofilm formation and its genes expressions in Staphylococcus epidermidis isolated from urinary tract infections of children in Isfahan

Aims: Staphylococcus epidermidis is an important bacterium, also one of the 40 species related to the Staphylococcus family. It can be found in the human normal body flora, commonly on the skin, and less commonly on mucosal flora. Instrument and Methods: In the cross-sectional study, we were isolated samples according to the laboratories standards, and S. epidermidis identification were collected for 1 year, 90 S. epidermidis from urinary tract infections of children were selected from educational hospitals in Isfahan, (Iran). In this way, we use the Kirby–Bauer method. S. epidermidis isolates were collected for determined biofilm producing method, with culturing in (Congo red agar) medium and microplate titration. Results: The results reveal that 45 methicillin resistance S. epidermidis isolates produce biofilm in different levels. The high resistance was for methicillin (50%), erythromycin (43.5%), ciprofloxacin (50.2%), and penicillin (46.9%). The lowest resistance was for linezolid (4%) and nitrofurantoin (5%). Conclusions: The results of our study show the high prevalence of antibiotic-resistant and biofilm producing of S. epidermidis strains, especially, in methicillin resistance S. epidermidis strains in the Isfahan hospitals, which could be a reservoir for antibiotic resistance genes.

The Human Immune System against Staphylococcus epidermidis.

Staphylococcus epidermidis is one of the major causes of nosocomial infections in humans. This organism can exist as a commensal on the skin. However, it can also lead to severe infections. The immune system has evolved mechanisms to deal with microorganisms and has strategies to combat bacteria. The initial defense against S. epidermidis infections includes the activation of complement complex, recruitment and then killing of the microorganism by effectors. The success of pathogenic S. epidermidis strains has been attributed to their capacity to evade innate immune cells. Extracellular matrix binding protein, polysaccharide intercellular adhesin, and accumulation-associated protein have been found to suppress killing of S. epidermidis by effector cells. PSM constitutes the only kind of exported toxins in S. epidermidis strains and has strong cytolytic features against leukocyte cells. The human innate immune system can be stimulated against S. epidermidis via toll-like receptors that enhance antibacterial reactions, trigger inflammation, and result in the stimulation of immune system effectors, e.g., type-1 interferon (IFN-alpha and IFN-beta), proinflammatory cytokines, and nitric oxide. Proinflammatory cytokines, e.g., interleukin-1, interleukin-6, and tumor necrosis factor are formed from resident human cells and result in migration of the lymphocyte and fever. In this review we will examine the immune system's response against S. epidermidis.

Study of Alnus incana L. Moench fruit extract biologically active substances influence on resistance development in mls-resistant staphylococci skin isolates

The emergence of microorganisms resistant strains is a natural biological response to the use of antimicrobial drugs that creates selective pressure, contributing to pathogens selection, survival and reproduction. The purpose of the investigation was to study the resistance development of staphylococci skin isolates to erythromycin and influence on it Alnus incana L. fruit extract subinhibitory concentrations. Development of resistance to erythromycin and influence on it Alnus incana L. fruit extract (extraction by 90% ethanol) subinhibitory concentrations were conducted with S epidermidis strains: sensitive and resistant to 14 and 15-membered macrolides. The study was carried out within 30 days by multiple consecutive passages of staphylococci test strains (concentration 1×107 CFU/ml) into test tubes containing broth and erythromycin ranging from 3 doubling dilutions above to doubling dilutions below the minimum inhibitory concentration. Statistical analysis of the results was carried out by one-and two-factor analysis of variance (ANOVA) and Microsoft Office Excel 2011. Rapid increase of resistance from 32 to 1024 μg/ml (F=34.2804; F> Fstand. max = 5.9874; p=0.0011) for S.epidermidis with a low level of resistance to 14 and 15-membered macrolides resistance to the erythromycine was observed. In the presence of Alnus incana L. fruit extract subinhibitory concentrations (¼ MIC), the initial MIC of erythromycin was decreased by 32 times to 1 μg/ml (F = 9.7497; F> Fstand. max = 5.9874; p = 0.0205). The sensitive strain after 30 passages did not develop resistance to erythromycin. Under the influence of erythromycin selective pressure, S.epidermidis strain with low initial level of MLS-resistance rapidly reaches a high-level resistance. Biologically active substances of the Alnus incana L. fruit extract significantly inhibit the resistance development in S. epidermidis to macrolides and eliminate it phenotypic features.

Bactericidal activity of gallium-doped chitosan coatings against staphylococcal infection.

The aim of this study was to develop a new class of gallium (Ga)-doped chitosan (CS) coatings fabricated by electrophoretic deposition (EPD) in staphylococcal infection therapy. Biofilm formation on EPD CS/Ga coatings by Staphylococcus epidermidis and Staphylococcus aureus, which are the main strains involved in postarthroplasty infections, was assessed. The codeposition of an antibacterial agent was effective; Ga loaded into CS matrix reduces biofilm viability by up to 86% and 80% for S.epidermidis and S.aureus strains respectively. Lastly, the influence of pulsed electromagnetic field (PEMF) on the bactericidal activity of CS/Ga coatings was investigated invitro. To this end, the coatings were incubated with S.epidermidis and S.aureus and exposed to the PEMF using two different frequencies and times. Biofilm viability for S.epidermidis was decreased by 35-40% in the presence of low-frequency (LF) and high-frequency (HF) PEMF respectively. Biofilm viability by S.aureus was not further reduced in the presence of LF PEMF, but decreased by 38% at HF PEMF. This study has established that a combination of PEMFs with the antibacterial agent improves bactericidal activity of Ga against S.epidermidis strain 14990 and S.aureus strain 12600. This new integrated approach could reduce the incidence of infection in orthopaedic implant applications. It also clearly demonstrates that the combination of Ga treatment with PEMF could aid biofilm-associated infection therapy due to improved Ga efficiency.

Antibacterial and anti-biofilm activities of cinnamaldehyde against S. epidermidis

The search for new antimicrobial drugs has been necessary due to the increased bacterial resistance to antibiotics currently in use, and natural products play an important role in this field. The aim of this study was to evaluate the in vitro effect of cinnamaldehyde on S. epidermidis strains, biofilm set-up prevention, as well as its effect on pre-established biofilms. The minimum inhibitory concentration (MIC) ranged from 300 to 500 μg/mL, and the minimum bactericidal concentration (MBC) from 400 to 600 μg/mL. The biofilm inhibitory concentration and biofilm eradication concentration values were four-fold (clinical isolate) and eight-fold (ATCC strain) greater than the concentration required to inhibit planktonic growth. Sub-inhibitory concentrations of cinnamaldehyde attenuated biofilm formation of S. epidermidis strains on polystyrene microtiter plates. The combination of cinnamaldehyde and linezolid was able to inhibit S. epidermidis with a bactericidal effect. Further investigation of the mechanism of action of cinnamaldehyde revealed its effect on the cell membrane permeability, and confocal laser scanning microscopy (CLSM) images illustrated the impact of cinnamaldehyde in the detachment and killing of existing biofilms. Thereby, our data confirmed the ability of cinnamaldehyde to reduce bacterial planktonic growth of S. epidermidis, inhibiting biofilm formation and eradicating pre-formed biofilm.

Zirconium Nitride Coating Reduced Staphylococcus epidermidis Biofilm Formation on Orthopaedic Implant Surfaces: An In Vitro Study.

One of the most commonly identified pathogens responsible for orthopaedic implant infection is Staphylococcus epidermidis, which can form biofilms on surfaces. Currently, orthopaedic implants made of various surface materials are available, each with features influencing osseointegration, biocompatibility, and adherence of bacteria to the surface, which is the first step in biofilm formation. The aim of this experimental study was to investigate the effect of a high tribologic-resistant 2.5-µm zirconium nitride top coat on an antiallergic multilayer ceramic-covered cobalt-chromium-molybdenum surface on the formation of S. epidermidis biofilm compared with other commonly used smooth and rough orthopaedic implant surface materials. (1) When evaluating the surfaces of a cobalt-chromium-molybdenum (CoCrMo) alloy with a zirconium (Zr) nitride coating, a CoCrMo alloy without a coating, titanium alloy, a titanium alloy with a corundum-blasted rough surface, and stainless steel with a corundum-blasted rough surface, does a Zr coating reduce the number of colony-forming units of S. epidermidis in an in vitro setting? (2) Is there quantitatively less biofilm surface area on Zr-coated surfaces than on the other surfaces tested in this in vitro model? To determine bacterial adhesion, five different experimental implant surface discs were incubated separately with one of 31 different S. epidermidis strains each and subsequently sonicated. Twenty test strains were obtained from orthopaedic patients undergoing emergency hip prosthesis surgeries or revision of implant infection and 10 further strains were obtained from the skin of healthy individuals. Additionally, one reference strain, S. epidermidis DSM 3269, was tested. After serial dilutions, the number of bacteria was counted and expressed as colony-forming units (CFUs)/mL. For biofilm detection, discs were stained with 0.1% Safranin-O for 15 minutes, photographed, and analyzed with computer imaging software. The lowest bacterial count was found in the CoCrMo + Zr surface disc (6.6 x 10 CFU/mL ± 4.6 x 10 SD) followed by the CoCrMo surface (1.1 x 10 CFU/mL ± 1.9 x 10 SD), the titanium surface (1.36 x 10 CFU/mL ± 1.8 x 10 SD), the rough stainless steel surface (2.65 x 10 CFU/mL ± 3.8 x 10 SD), and the rough titanium surface (2.1 x 10 CFU/mL ± 3.0 x 10 SD). The mean CFU count was lower for CoCrMo + Zr discs compared with the rough stainless steel surface (mean difference: 2.0 x 10, p = 0.021), the rough titanium alloy surface (mean difference: 1.4 x 10, p = 0.002), and the smooth titanium surface (mean difference: 7.0 x 10, p = 0.016). The results of biofilm formation quantification show that the mean covered area of the surface of the CoCrMo + Zr discs was 19% (± 16 SD), which was lower than CoCrMo surfaces (35% ± 23 SD), titanium alloy surface (46% ± 20 SD), rough titanium alloy surface (66% ± 23 SD), and rough stainless steel surface (58% ± 18 SD). These results demonstrate that a multilayer, ceramic-covered, CoCrMo surface with a 2.5-µm zirconium nitride top coat showed less S. epidermidis biofilm formation compared with other surface materials used for orthopaedic implants. CoCrMo with a 2.5-µm zirconium nitride top coat seems to be a promising surface modification technology able to reduce bacterial attachment on the surface of an implant and, hence, may further prevent implant infection with S. epidermidis biofilm formation.

Antimicrobial Susceptibility test and DNA gyrase analysis of Coagulase-negative <i>Staphylococci</i> isolated

Purpose : We investigated the susceptibility of quinolone series and vancomycin, erythromycin antibiotics for isolates of Coagulase-negative Staphylococci and analyzed the DNA gyrase gene. Methods : Antibiotic susceptibility ofloxacin, ciprofloxacin, levofloxacin, vancomycin, and erythromycin were studied in six strains of coagulase-negative Staphylococci detected in corneas of suspected bacterial keratitis. Antibiotic susceptibility ofloxacin, ciprofloxacin, levofloxacin, vancomycin, and erythromycin were studied in six strains of coagulase-negative Staphylococci detected in corneas of suspected bacterial keratitis. and the genomic DNA of each strain was extracted. After amplifying PCR, DNA of gyraseA gene was analyzed. Results : In the antibiotic susceptibility test, ofloxacin, ciprofloxacin, levofloxacin and vancomycin susceptibility, and erythromycin resistance were observed in strains of S. epidermidis (SE-2, SE-3), S. hominis (SH-1) and S. saprophyticus (SS-1), showing that all of the other strains were susceptible. In the gyraseA gene analysis, amino acid double mutation was observed from S. epidermidis (SE-1) strain as Met75→Thr and Met93→Val, and many silent mutations were observed in strains of S. warneri (SW-1) and S. saprophyticus (SS-1). Conclusions : The isolates of Coagulase-negative Staphylococci showed resistance to erythromycin antibiotics, and amino acid double mutation and silent mutation were observed from gyraseA gene analysis. Therefore, although it is not resistance now, potential mutations would be thought that can cause resistance at any time.

Molecular Characteristics of Biofilm-Producing Methicillin-Resistant Staphylococcus epidermidis Isolates Causing Urinary Tract Infections

Background: Coagulase-negative Staphylococcus epidermidis is the most prevalent member of the human skin normal biota that plays an important role as a common cause of catheter and prosthetic device-related infections from, for example, indwelling catheters. Objectives: This study aimed to characterize the clonality of biofilm-producing methicillin-resistant S. epidermidis (MRSE) strains isolated from catheterized patients with urinary tract infection at a referral hospital in Tehran, Iran. Methods: Between 2014 and 2016, a total of 56 methicillin-resistant S. epidermidis (MRSE) strains were recovered from catheterized patients. The MRSE isolates were tested for biofilm formation and different genes involved in this process were detected. Clonal dissemination of MRSE isolates was determined using the combination of pulsed-field gel electrophoresis (PFGE) and SCCmec typing. Results: Out of the 56 MRSE strains, 50 (89%) formed biofilm and were positive for icaA and icaD genes, and 73% (n = 41) harbored IS256. The PFGE patterns revealed a total of 32 different pulsotypes consisting of 16 single types (STs), 16 common types (CTs), and 2 SCCmec types (III and IV) were detected. Moreover, all STs carried SCCmec type IV and classified as community-acquired strains. Four CTs were common among biofilm and non-biofilm producing strains. Conclusions: The presence of icaA and icaD genes with a high prevalence of IS256 element in clonal groups of MRSE strains suggests that ica, IS256, and biofilm forming ability occur simultaneously in specific S. epidermidis clones and spread preferentially in hospitals and community.

Reductive amination of ketones with ammonium catalyzed by a newly identified Brevibacterium epidermidis strain for the synthesis of (S)-chiral amines

The asymmetric reductive amination of achiral ketones with ammonia is a particularly attractive reaction for the synthesis of chiral amines. Although several engineered amine dehydrogenases have been developed by protein engineering for the asymmetric reductive amination of ketones, they all display (R)-stereoselectivity. To date, there is no report of an (S)-stereoselective biocatalyst for this reaction. Herein, a microorganism named Brevibacterium epidermidis ECU1015 that catalyzes the (S)-selective reductive amination of ketones with ammonium has been successfully isolated from soil. Using B. epidermidis ECU1015 as the catalyst, the asymmetric reductive amination of a set of phenylacetone derivatives was successfully carried out, yielding the corresponding (S)-chiral amines with moderate conversion and >99% enantiomeric excess.

Biofilm production and antibiotic susceptibility of Staphylococcus epidermidis strains from Hidradenitis Suppurativa lesions.

An aberrant interaction between commensal skin bacteria and the host skin immune system is considered important in the pathogenesis of hidradenitis suppurativa (HS). In this study, we investigated the antibiotic susceptibility and biofilm-forming capabilities of S. epidermidis strains isolated from HS patients. Skin biopsies were taken from active HS lesions such as inflammatory nodules and/or sinuses and non-involved skin from 26 patients and cultured under optimal microbiological conditions for 24 h. Planktonic growth, biofilm production, antibiotic susceptibility and biofilm eradication by clindamycin, doxycycline, rifampicin and tetracycline were tested including a laboratory control strain of S. epidermidis for reference. Staphylococcus epidermidis was cultured in 16 of 26 HS patients (62%). In total 27 different S. epidermidis isolates were identified; 16 (59%) from non-involved skin and 11 (41%) from HS lesions. All bacterial strains showed planktonic growth. Twenty-four of 27 (89%) isolates were strong biofilm producers in vitro. The biofilm-forming capability varied amongst the strains from non-involved skin and lesional skin. Twenty-four strains had an intermediate to resistant antibiotic susceptibility to clindamycin (89%). Rifampicin was the most effective antibiotic at inhibiting planktonic growth and at eradication of biofilm (P < 0.05). We observed a slight increase in S. epidermidis virulence, characterized by resistance to commonly used antibiotics, increased biofilm production and resistance to biofilm eradication. In particular, the reduced sensitivity to tetracycline and clindamycin, two standard antibiotics in the treatment of HS, is alarming. Rifampicin, also important in HS treatment, showed the greatest efficacy at eradicating the biofilm at low MIC concentrations.

Isolation of Bacteriocin-producing Staphylococcus spp. Strains from Human Skin Wounds, Soft Tissue Infections and Bovine Mastitis.

A collection of 206 Staphylococcus spp. isolates was investigated for their ability to produce compounds exhibiting antistaphylococcal activity. This group included Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus xylosus strains recovered from bovine mastitis (n = 158) and human skin wounds and soft tissues infections (n = 48). Production of substances with antimicrobial activity was observed in six strains. Five of them were recovered from bovine mastitis, and one was isolated from the infected human skin wound. Three of the six antimicrobials produced by the different strains showed substantial loss of antimicrobial activity upon treatment with proteolytic enzymes, which suggests their peptidic structure. Additional studies have shown that one of the putative bacteriocins was efficiently secreted to the liquid medium, facilitating its large-scale production and isolation. The peptide produced by the M2B strain exhibited promising activity; however, against narrow spectrum of Staphylococcus spp. clinical and animal isolates. Growth inhibition was observed only in the case of 13 (including nine S. aureus, three S. xylosus and one S. epidermidis strains) out of 206 strains tested. Important advantage of the produced agent was its high thermal stability. Fifteen minutes of incubation at 90°C did not affect its antimicrobial potential. The highest efficiency of production of the agent was demonstrated in TSB medium after 24 hours at 37°C. The researches revealed that ability to production of bacteriocin among staphylococci is not very common. Only one (S. xylosus strain assigned as M2B) out of 206 strains tested produced satisfactory amounts of antistaphylococcal bacteriocin. In spite of that, we would encourage other researchers for investigation of their collections of Staphylococcus spp. isolates towards selection strains producing antimicrobial agents.

Chemical composition, antimicrobial and antibiofilm efficacy of C. limon and L. angustifolia EOs and of their mixtures against Staphylococcus epidermidis clinical strains

Staphylococcus epidermidis is a Gram-positive resident of the human skin, which in certain conditions, can turn into an opportunistic pathogen, being one of the most frequent agents of nosocomial infections, particularly of those associated with indwelling medical devices. The aim of this study was to evaluate the antimicrobial and antibiofilm activity of two essential oils (EOs) to be used alone or in combination as natural alternatives to currently available antibiotics, for treating S. epidermidis infections or preventing the contamination and further development of S. epidermidis biofilm on viable tissues or medical devices. For this purpose C. limon and L. angustifolia EOs were obtained both by hydrodistillation and microwave-assisted extraction and analyzed by GC–MS. The compositions of EOs as a function of the extraction procedure were compared and discussed. Each of the two extraction techniques was more effective in the extraction of different components of the EOs. In the case of C. limon EOs, terpinen-4-ol, α-terpineol and linalool, not found in the microwave assisted extract, are obtained by classical hydrodistillation (being compounds of high polarity) while less polar compounds (α-pinene, β-pinene, limonene, γ-terpinene) are drawn into higher percentage through the microwave-assisted procedure. In the case of L. angustifolia EOs, a higher percentage of compounds with high polarity (such as linalool) is extracted by classical hydrodistillation while the compounds with lower polarity, such as acetates (linalyl acetate and neryl acetate) are extracted in higher proportion by the microwave-assisted extraction method.The antibacterial and antibiofilm effects of the EOs and of their mixtures were tested towards five S. epidermidis clinical strains and their biological activity was correlated with the oils composition. The most active composition was represented by the binary mixture (1:1) of the EOs obtained by hydrodistillation, containing terpene alcohols (such linalool) and d-limonene, which exhibited the lowest minimum inhibitory concentration (3.9 μg/mL) and minimum biofilm eradicating concentration (0.97–7.81 μg/mL), against all tested S. epidermidis strains. Other minor constituents, such as terpinen-4-ol, α-terpineol, linalyl acetate, neryl acetate, geranyl acetate and α-pinene could be potentiated in presence of limonene and could be responsible for the high antimicrobial activity of these EOs mixture.

Induced surface proteins of Staphylococcus [corrected] epidermidis adhering to titanium implant substrata.

Staphylococcus epidermidis, as a primary colonizer, is strongly associated with infections of (dental) implants (i.e., peri-implantitis), but little is known about the surface proteome of this bacterium. For the identification of bacterial adhesins, this study investigated the surface proteome of S. epidermidis adhering directly to titanium implant substrata. S. epidermidis strain ATTC 35984 was cultured either planktonically or on titanium implant specimens. The surface proteomes were isolated by mutanolysin digestion, and proteins were separated by 2D gel electrophoreses to reveal highly expressed proteins only. Protein spots were visualized by silver staining and proteins were identified by mass spectrometry. Surface proteome analyses of S. epidermidis on titanium identified six expressed proteins. Three proteins were highly expressed on the titanium implants including accumulation-associated protein Q8CQD9. These specific proteins could be potential pathogenicity factors of bacteria in peri-implant biofilms. For the first time, our study identified S. epidermidis surface proteins, which are expressed after adhesion to titanium implant materials. Our study reveals possible candidates for a newly protein-based vaccine against peri-implantitis.

The prevalence, antibiotic resistance and mecA characterization of coagulase negative staphylococci recovered from non-healthcare settings in London, UK

BackgroundCoagulase negative staphylococci (CoNS) are important reservoirs of antibiotic resistance genes and associated mobile genetic elements and are believed to contribute to the emergence of successful methicillin resistant Staphylococcus aureus (MRSA) clones. Although, these bacteria have been linked to various ecological niches, little is known about the dissemination and genetic diversity of antibiotic resistant CoNS in general public settings.MethodsFour hundred seventy-nine samples were collected from different non-healthcare/general public settings in various locations (n = 355) and from the hands of volunteers (n = 124) in London UK between April 2013 and Nov 2014.ResultsSix hundred forty-three staphylococcal isolates belonging to 19 staphylococcal species were identified. Five hundred seventy-two (94%) isolates were resistant to at least one antibiotic, and only 34 isolates were fully susceptible. Sixty-eight (11%) mecA positive staphylococcal isolates were determined in this study. SCCmec types were fully determined for forty-six isolates. Thirteen staphylococci (19%) carried SCCmec V, followed by 8 isolates carrying SCCmec type I (2%), 5 SCCmec type IV (7%), 4 SCCmec type II (6%), 1 SCCmec type III (2%), 1 SCCmec type VI (2%), and 1 SCCmec type VIII (2%). In addition, three isolates harboured a new SCCmec type 1A, which carried combination of class A mec complex and ccr type 1.MLST typing revealed that all S. epidermidis strains possess new MLST types and were assigned the following new sequence types: ST599, ST600, ST600, ST600, ST601, ST602, ST602, ST603, ST604, ST605, ST606, ST607 and ST608.ConclusionsThe prevalence of antibiotic resistant staphylococci in general public settings demonstrates that antibiotics in the natural environments contribute to the selection of antibiotic resistant microorganisms. The finding of various SCCmec types in non-healthcare associated environments indicates the complexity of SCCmec. We also report on new MLST types that were assigned for all S. epidermidis isolates, which demonstrates the genetic variability of these isolates.

Modulation of S. epidermidis-induced innate immune responses in neonatal whole blood.

Coagulase-negative staphylococci (CoNS) such as Staphylococcus epidermidis are highly prevalent pathogens for sepsis in neonates. The interaction between host, environment and pathogenic factors of S. epidermidis are still poorly understood. Our objective was to address the role of several pathogenic factors of S. epidermidis on neonatal cytokine responses and to characterize the influence of three immunomodulatory drugs. We performed an ex-vivo model of S. epidermidis sepsis by assessment of blood cytokine production in neonatal whole blood stimulation assays (ELISA). S. epidermidis strains with different characteristics were added as full pathogen to umbilical cord blood cultures and the influence of indomethacin, ibuprofen and furosemide on neonatal immune response to S. epidermidis was evaluated (Flow cytometry). Stimulation with S. epidermidis sepsis strains induced higher IL-6 and IL-10 expression than stimulation with colonization strains. Biofilm formation in clinical isolates was associated with increased IL-10 but not IL-6 levels. In contrast, stimulation with mutant strains for biofilm formation and extracellular virulence factors had no major effect on cytokine expression. Notably, addition of ibuprofen or indomethacin to S. epidermidis inoculated whole blood resulted in mildly increased expression of TNF-α but not IL-6, while frusemide decreased the production of pro-inflammatory cytokines, i.e. IL-6 and IL-8. The virulence of sepsis strains is coherent with increased cytokine production in our whole-blood in-vitro sepsis model. Biofilm formation and expression of extracellular virulence factors had no major influence on readouts in our setting. It is important to acknowledge that several drugs used in neonatal care have immunomodulatory potential.

Arginine Catabolic Mobile Elements in Livestock-Associated Methicillin-Resistant Staphylococcal Isolates From Bovine Mastitic Milk in China.

The arginine catabolic mobile element (ACME) facilitates colonization of staphylococci on skin and mucous membranes by improving their tolerances to polyamines and acidic conditions. ACME is inserted in tandem with the SCCmec element and Staphylococcus epidermidis has been proposed to be a reservoir of ACME for other staphylococci. In this study, we investigated the existence of ACME in 146 staphylococcal isolates from mastitic milk and found 21 of them carried ACME. Almost half of the investigated S. epidermidis isolates contained the element. The whole genome of a S. epidermidis strain Y24 with ACME was further sequenced and the ACME-SCCmec composite island was assembled. This composite island is 81.3 kb long and consisted of 77 ORFs including a methicillin resistance gene mecA, a type II’ ACME gene cluster, a virulence gene pls and eight heavy metal tolerance genes. Wide existence of ACME in livestock-associated staphylococci from this study and a potential risk of spreading ACME among different staphylococcal species warrant close monitoring and further studies.