Foreign body infections due to Staphylococcus epidermidis

General skin and nasal decolonization with octenisan® set before and after elective orthopedic surgery in selected patients at elevated risk for revision surgery and surgical site infections-a single-center, unblinded, superiority, randomized controlled trial (BALGDEC trial)

BACKGROUND

The preoperative body surface and nasal decolonization may reduce the risk of surgical site infections (SSI) but yields conflicting results in the current orthopedic literature.

METHODS

We perform a single-center, randomized-controlled, superiority trial in favor of the preoperative decolonization using a commercial product (octenidine® set). We will randomize a total number of 1000 adult elective orthopedic patients with a high risk for SSI and/or wound complications (age ≥ 80 years, chronic immune-suppression, American Society of Anesthesiologists score 3-4 points) between a decolonization (octenisan® wash lotion 1 × per day and octenisan® md nasal gel 2-3 × per day; during 5 days) and no decolonization. Decolonized patients will additionally fill a questionnaire regarding the practical difficulties, the completeness, and the adverse events of decolonization. The primary outcomes are SSI and revision surgeries for postoperative wound problems until 6 weeks postoperatively (or 1 year for surgeries with implants or bone). Secondary outcomes are unplanned revision surgeries for non-infectious problems and all adverse events. With 95% event-free surgeries in the decolonization arm versus 90% in the control arm, we formally need 2 × 474 elective orthopedic surgeries included during 2 years.

DISCUSSION

In selected adult orthopedic patients with a high risk for SSI, the presurgical decolonization may reduce postoperative wound problems, including SSI.

TRIAL REGISTRATION

ClinicalTrial.gov NCT05647252. Registered on 9 December 2022.

PROTOCOL VERSION

2 (5 December 2022).

Community assembly of the human piercing microbiome

Predicting how biological communities respond to disturbance requires understanding the forces that govern their assembly. We propose using human skin piercings as a model system for studying community assembly after rapid environmental change. Local skin sterilization provides a 'clean slate' within the novel ecological niche created by the piercing. Stochastic assembly processes can dominate skin microbiomes due to the influence of environmental exposure on local dispersal, but deterministic processes might play a greater role within occluded skin piercings if piercing habitats impose strong selection pressures on colonizing species. Here we explore the human ear-piercing microbiome and demonstrate that community assembly is predominantly stochastic but becomes significantly more deterministic with time, producing increasingly diverse and ecologically complex communities. We also observed changes in two dominant and medically relevant antagonists (Cutibacterium acnes and Staphylococcus epidermidis), consistent with competitive exclusion induced by a transition from sebaceous to moist environments. By exploiting this common yet uniquely human practice, we show that skin piercings are not just culturally significant but also represent ecosystem engineering on the human body. The novel habitats and communities that skin piercings produce may provide general insights into biological responses to environmental disturbances with implications for both ecosystem and human health.

Staphylococcus epidermidis activates keratinocyte cytokine expression and promotes skin inflammation through the production of phenol-soluble modulins

Staphylococcus epidermidis is a common microbe on human skin and has beneficial functions in the skin microbiome. However, under conditions of allergic inflammation, the abundance of S. epidermidis increases, establishing potential danger to the epidermis. To understand how this commensal may injure the host, we investigate phenol-soluble modulin (PSM) peptides produced by S. epidermidis that are similar to peptides produced by Staphylococcus aureus. Synthetic S. epidermidis PSMs induce expression of host defense genes and are cytotoxic to human keratinocytes. Deletion mutants of S. epidermidis lacking these gene products support these observations and further show that PSMs require the action of the EcpA bacterial protease to induce inflammation when applied on mouse skin with an intact stratum corneum. The expression of PSMδ from S. epidermidis is also found to correlate with disease severity in patients with atopic dermatitis. These observations show how S. epidermidis PSMs can promote skin inflammation.

Decreased susceptibility to vancomycin and other mechanisms of resistance to antibiotics in Staphylococcus epidermidis as a therapeutic problem in hospital treatment

Multidrug-resistant coagulase-negative staphylococci represent a real therapeutic challenge. The aim of the study was to emphasize the importance of heteroresistance to vancomycin presence in methicillin-resistant strains of S. epidermidis. The research comprised 65 strains of S. epidermidis. Heteroresistance to vancomycin was detected with the use of the agar screening method with Brain Heart Infusion and a population profile analysis (PAP test). In addition, types of cassettes and genes responsible for resistance to antibiotics for 22 multidrug resistant strains were determined. Our investigations showed that 56 of 65 S. epidermidis strains were phenotypically resistant to methicillin. The tested strains were mostly resistant to erythromycin, gentamicin, clindamycin, and ciprofloxacin. Six strains showed decreased susceptibility to vancomycin and their heterogeneous resistance profiles were confirmed with the PAP test. All tested multi-resistant strains exhibited the mecA gene. More than half of them possessed type IV cassettes. ant(4')-Ia and aac(6')/aph(2''), ermC and tetK genes were most commonly found. The described phenomenon of heteroresistance to vancomycin in multidrug resistant bacteria of the Staphylococcus genus effectively inhibits a therapeutic effect of treatment with this antibiotic. That is why it is so important to search for markers that will enable to identify heteroresistance to vancomycin strains under laboratory conditions.

Identification and Characterization of a Vancomycin Intermediate-Resistant Staphylococcus haemolyticus Isolated from Guangzhou, China

Background

Staphylococcus haemolyticus is an opportunistic pathogen that belongs to coagulase-negative Staphylococci (CoNS). Increasing infection and multi-drug resistance cases caused by this strain have been reported and thus it poses a great health threat.

Methods

The third-generation sequencing technology was performed on a S. haemolyticus SH-1 isolated from a clinical sample to analyze the drug resistance genes, which included vancomycin resistance related genes. In addition, antimicrobial susceptibility tests, transmission electron microscopy and Triton X-100 stimulated autolysis were conducted to understand its biological characteristics.

Results

The study shows that this clinical isolate is a vancomycin intermediate-resistant strain. Genome comparison also revealed that WalK(N70K) and WalK(R280Q) mutations may contribute to the vancomycin resistant phenotype. Besides, S. haemolyticus SH-1 exhibit common features of thicker cell wall and decreased autolytic activity.

Conclusion

S. haemolyticus SH-1 with WalKR mutations shows typical characteristics of vancomycin resistant strains. Combining the genome features and biological properties, our findings may provide important information for the understanding of the molecular mechanism of S. haemolyticus to vancomycin intermediate-resistance.

Dynamic Distribution of Skin Microorganisms in Donkeys at Different Ages and Various Sites of the Body

Considerable evidence suggests that the skin microbiota is not only important and complex in humans and other mammals but also critical for maintaining health and skin homeostasis. To date, studies on the skin microorganisms of donkeys are surprisingly rare. To investigate the dynamic changes in commensal microbial communities on the skins of healthy donkeys throughout the growing period, skin and soil samples were collected from 30 healthy Dezhou donkeys (ranging from 1, 6, 12, 24 to 48 months of age) and their corresponding breeding sheds on the farm. All samples were analysed for high-throughput sequencing of the 16S rRNA and ITS to characterize the skin microbiota of healthy donkeys and compare the differences in skin microbiota among donkeys of different ages. There were notable differences in the proportions of various genera (including bacteria and fungi) between dorsal and abdominal skin with increasing age. The comparison of the skin microbial communities among these groups revealed that Staphylococcus was mainly enriched in the early growing stage (1 and 6 months), while the relative abundance of Streptococcus was higher in both the 1- and 48-month-old age groups. Moreover, some bacteria and commensal fungi, such as Staphylococcus and Trichosporon, were found to be positively correlated between the skin and the environment. This is the first study to investigate the dynamic changes in skin microbiota diversity and composition in donkeys of different ages and at different sites of the body. Furthermore, this study provides insights into the dynamic alterations in skin microbes during a donkey's growth and characterizes the profiles of bacterial and fungal communities across a donkey's body regions (dorsal and abdomen).

Host Immune Regulation in Implant-Associated Infection (IAI): What Does the Current Evidence Provide Us to Prevent or Treat IAI?

The number of orthopedic implants for bone fixation and joint arthroplasty has been steadily increasing over the past few years. However, implant-associated infection (IAI), a major complication in orthopedic surgery, impacts the quality of life and causes a substantial economic burden on patients and societies. While research and study on IAI have received increasing attention in recent years, the failure rate of IAI has still not decreased significantly. This is related to microbial biofilms and their inherent antibiotic resistance, as well as the various mechanisms by which bacteria evade host immunity, resulting in difficulties in diagnosing and treating IAIs. Hence, a better understanding of the complex interactions between biofilms, implants, and host immunity is necessary to develop new strategies for preventing and controlling these infections. This review first discusses the challenges in diagnosing and treating IAI, followed by an extensive review of the direct effects of orthopedic implants, host immune function, pathogenic bacteria, and biofilms. Finally, several promising preventive or therapeutic alternatives are presented, with the hope of mitigating or eliminating the threat of antibiotic resistance and refractory biofilms in IAI.

First Synthesis of DBU-Conjugated Cationic Carbohydrate Derivatives and Investigation of Their Antibacterial and Antifungal Activity

The emergence of drug-resistant bacteria and fungi represents a serious health problem worldwide. It has long been known that cationic compounds can inhibit the growth of bacteria and fungi by disrupting the cell membrane. The advantage of using such cationic compounds is that the microorganisms would not become resistant to cationic agents, since this type of adaptation would mean significantly altering the structure of their cell walls. We designed novel, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene)-derived amidinium salts of carbohydrates, which may be suitable for disturbing the cell walls of bacteria and fungi due to their quaternary ammonium moiety. A series of saccharide-DBU conjugates were prepared from 6-iodo derivatives of d-glucose, d-mannose, d-altrose and d-allose by nucleophilic substitution reactions. We optimized the synthesis of a d-glucose derivative, and studied the protecting group free synthesis of the glucose-DBU conjugates. The effect of the obtained quaternary amidinium salts against Escherichia coli and Staphylococcus aureus bacterial strains and Candida albicans yeast was investigated, and the impact of the used protecting groups and the sugar configuration on the antimicrobial activity was analyzed. Some of the novel sugar quaternary ammonium compounds with lipophilic aromatic groups (benzyl and 2-napthylmethyl) showed particularly good antifungal and antibacterial activity.

Synergistic Potentiation of Antimicrobial and Antibiofilm Activities of Penicillin and Bacitracin by Octyl Gallate, a Food-Grade Antioxidant, in Staphylococcus epidermidis

Staphylococcus epidermidis is a major nosocomial pathogen that frequently forms biofilms on indwelling medical devices. This study aimed to investigate the synergistic antimicrobial and antibiofilm activities of octyl gallate (OG) in combination with penicillin and bacitracin against S. epidermidis. Antimicrobial synergy was assessed by conducting checkerboard titration assays, and antibiofilm activity was determined with biofilm assays and fluorescence microscopy analysis. The presence of 8 µg/mL of OG increased both the bacteriostatic and bactericidal activities of penicillin and bacitracin against S. epidermidis. It lowered the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of penicillin by eight-fold and those of bacitracin by four-fold. Moreover, when used with penicillin or bacitracin, OG significantly decreased the level of biofilm production by preventing microcolony formation. Furthermore, OG significantly permeabilized the bacterial cell wall, which may explain its antimicrobial synergy with penicillin and bacitracin. Together, these results demonstrate that OG, a food-grade antioxidant, can be potentially used as a drug potentiator to enhance the antimicrobial and antibiofilm activities of penicillin and bacitracin against S. epidermidis.

A Combination of Pharmacophore-Based Virtual Screening, Structure-Based Lead Optimization, and DFT Study for the Identification of S. epidermidis TcaR Inhibitors

The transcriptional regulator (TcaR) enzyme plays an important role in biofilm formation. Prevention of TcaR-DNA complex formation leads to inhibit the biofilm formation is likely to reveal therapeutic ways for the treatment of bacterial infections. To identify the novel ligands for TcaR and to provide a new idea for drug design, two efficient drug design methods, such as pharmacophore modeling and structure-based drug design, were used for virtual screening of database and lead optimization, respectively. Gemifloxacin (FDA-approved drug) was considered to generate the pharmacophore model for virtual screening of the ZINC database, and five hits, namely ZINC77906236, ZINC09550296, ZINC77906466, ZINC09751390, and ZINC01269201, were identified as novel inhibitors of TcaR with better binding energies. Using structure-based drug design, a set of 7a–7p inhibitors of S. epidermidis were considered, and Mol34 was identified with good binding energy and high fitness score with improved pharmacological properties. The active site residues ARG110, ASN20, HIS42, ASN45, ALA38, VAL63, VAL68, ALA24, VAL43, ILE57, and ARG71 are playing a promising role in inhibition process. In addition, we performed DFT simulations of final hits to understand the electronic properties and their significant role in driving the inhibitor to adopt apposite bioactive conformations in the active site. Conclusively, the newly identified and designed hits from both the methods are promising inhibitors of TcaR, which can hinder biofilm formation.

Fusions of a Carbohydrate Binding Module with the Small Cationic Hexapeptide RWRWRW Confer Antimicrobial Properties to Cellulose-based Materials

The emergence of antibiotic-resistant bacteria is a critical worldwide healthcare problem. In the specific case of wound care, new and effective alternatives to currently available solutions are urgently needed. Cellulose-based dressings, for example, could be made more attractive if rendered antimicrobial. This work proposes a new strategy to modify cellulose-based materials with the short antimicrobial hexapeptide MP196 (RWRWRW-NH₂) that relies on a biomolecular recognition approach based on carbohydrate binding modules (CBMs). Specifically, we focused on the modification of hydrogels, paper, and microfibrillated cellulose (MFC) with fusions of the CBM3 from Clostridium thermocellum (C. thermocellum) with derivatives of MP196. The fusions are prepared by promoting the formation of a disulfide bond between Cys-terminated derivatives of MP196 and a CBM3 that is pre-anchored in the materials. The CBM3-MP196-modified materials displayed antibacterial activity against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) that was significantly higher when compared with the activity of materials prepared by physical adsorption of MP196. The biomolecular strategy provides a more favorable orientation, exposure, and distancing of the peptide from the matrix. This versatile concept provides a toolbox for the functionalization of cellulose materials of different origins and architectures with a broad choice in peptides. Functionalization under mild biological conditions avoids further purification steps, allowing for translational research and multiple applications as drug delivery systems, scaffolds for tissue engineering and biomaterials. STATEMENT OF SIGNIFICANCE: The emergence of antibiotic-resistant bacteria is a critical worldwide healthcare problem. In the specific case of wound care, new and effective alternatives to currently available solutions are urgently needed. This work proposes a new strategy to modify cellulose-based materials with a short antimicrobial hexapeptide that relies on a biomolecular recognition approach based on carbohydrate binding modules. The modified materials displayed antibacterial activity against both Gram-negative and Gram-positive bacteria. The biomolecular strategy provides a favorable orientation, exposure, and distancing of the peptide from the matrix. This versatile concept offers a toolbox for the functionalization of different cellulose materials with a broad choice in peptides. Functionalization under mild biological conditions avoids further purification steps, allowing for translational research and multiple applications.

Molecular docking and simulation of IcaC protein as O-succinyltransferase function in staphylococcus epidermidis biofilm formation

Intercellular adhesion (IcaADBC) operon is necessary for PNAG (Polyβ-1,6-N-acetyl-D-glucosamine) biosynthesis of biofilm formation in Staphylococcus epidermidis. IcaC protein has a wide range of functions in terms of growth phase variation, migration, transposon insertion, PNAG modification, biofilm formation. Unusual TTTA signature motifs were identified from nucleotide sequence. Asparagine-linked glycosylation consensus motifs were identified at position 169 and 240. S. epidermidis was a close evolutionary association with S. haemolyticus and other Staphylococcus spp. Due to the non-availability of crystal structure, protein threading procedure was selected for constructing a full length IcaC three-dimensional structure. QMEANBrane structure quality assessment with model scores −100000 range within predicted integral membrane structure. IcaC motif constitutes 18 transmembrane helix, 37 helix-helix interaction, 8 beta turn, 2 gamma turn. Binding free energy was calculated with their succinate ligand docking form hydrogen bond with critical amino acids showed ΔG score −2.574 ​kJ/mol using Schrödinger. Serine (Ser96), Glutamic acid (Glu99), Tryptophan (Trp191) were active site amino acids form the catalytic core required for O-succinyltransferase function. Molecular dynamics simulation (MDS) was performed to evaluate the stability of IcaC protein and IcaC-Succinate binding complexes with the active site amino acids throughout trajectories captured with time scale 100 ns simulation period using GROMACS 4.5.

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Structural characterization of Intercellular adhesion (IcaC) protein from Staphylococcus epidermidis.

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Understanding of nucleotide, protein signature sequence, secondary structure motifs and phylogenetic association among Staphylococcus sp. homologs.

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IcaC-Succinate docking and molecular dynamics simulation for determined structural stability of protein.

The Response Surface Optimization of Supercritical CO2 Modified with Ethanol Extraction of p-Anisic Acid from Acacia mearnsii Flowers and Mathematical Modeling of the Mass Transfer

A widely disseminated native species from Australia, Acacia mearnsii, which is mainly cultivated in Brazil and South Africa, represents a rich source of natural tannins used in the tanning process. Many flowers of the Acacia species are used as sources of compounds of interest for the cosmetic industry, such as phenolic compounds. In this study, supercritical fluid extraction was used to obtain non-volatile compounds from A. mearnsii flowers for the first time. The extract showed antimicrobial activity and the presence of p-anisic acid, a substance with industrial and pharmaceutical applications. The fractionation of the extract was performed using a chromatographic column and the fraction containing p-anisic acid presented better minimum inhibitory concentration (MIC) results than the crude extract. Thus, the extraction process was optimized to maximize the p-anisic acid extraction. The response surface methodology and the Box–Behnken design was used to evaluate the pressure, temperature, the cosolvent, and the influence of the particle size on the extraction process. After the optimization process, the p-anisic acid yield was 2.51% w/w and the extraction curve was plotted as a function of time. The simulation of the extraction process was performed using the three models available in the literature.

Complete sequences of epidermin and nukacin encoding plasmids from oral-derived Staphylococcus epidermidis and their antibacterial activity

Staphylococcus epidermidis is a commensal bacterium in humans. To persist in the bacterial flora of the host, some bacteria produce antibacterial factors such as the antimicrobial peptides known as bacteriocins. In this study, we tried to isolate bacteriocin-producing S. epidermidis strains. Among 150 S. epidermidis isolates from the oral cavities of 287 volunteers, we detected two bacteriocin-producing strains, KSE56 and KSE650. Complete genome sequences of the two strains confirmed that they carried the epidermin-harboring plasmid pEpi56 and the nukacin IVK45-like-harboring plasmid pNuk650. The amino acid sequence of epidermin from KSE56 was identical to the previously reported sequence, but the epidermin synthesis-related genes were partially different. The prepeptide amino acid sequences of nukacin KSE650 and nukacin IVK45 showed one mismatch, but both mature peptides were entirely similar. pNuk650 was larger and had an additional seven ORFs compared to pIVK45. We then investigated the antibacterial activity of the two strains against several skin and oral bacteria and found their different activity patterns. In conclusion, we report the complete sequences of 2 plasmids coding for bacteriocins from S. epidermidis, which were partially different from those previously reported. Furthermore, this is the first report to show the complete sequence of an epidermin-carrying plasmid, pEpi56.

Physiochemical and bactericidal activity evaluation: Silver-augmented 3D-printed scaffolds-An in vitro study

HYPOTHESIS

Injuries requiring resection of tissue followed by autogenous bone transfer may be prone to infection by Staphylococcus aureus, impeding recovery and increasing medical costs. For critical sized defects, the common approach to reconstruction is a tissue transfer procedure but is subject to limitations (e.g., donor site morbidity, cost, operating time). Utilizing beta tricalcium phosphate (β-TCP) as bone grafting material augmented with silver (Ag), a custom graft may be 3D printed to overcome limitations and minimize potential infections.

EXPERIMENTS

Scaffolds were 3D printed and augmented with Ag by external attack on the surface by silver nitrate (AgNO3 ) at varying concentrations (0.1, 1.0, 10% wt/wt of scaffold). The augmented scaffolds were evaluated utilizing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and inductively coupled plasma mass spectroscopy (ICP-MS) to verify the presence of Ag and phosphate (PO4 ) groups followed by electron microscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) to gather information of chemical and physical properties. Preliminary biocompatibility and bactericidal capacity of the scaffolds were tested using human osteoprogenitor (hOP) cells and methicillin-sensitive S. aureus strain, respectively.

RESULTS

XRD, FTIR, ICP-MS, TGA, and DSC confirmed presence of Ag and PO4 groups, whereas electron microscopy showed a decrease in Ca and an increase in Ag ions, decreasing Ca/P ratio with increasing surfactant concentrations. PrestoBlue assays yielded an increase in fluorescence cell counts among experimental groups with lower concentrations of Ag characterized by their characteristic trapezoidal shape whereas cytotoxicity was observed at higher concentrations. Similar observations were made with alkaline phosphatase assays. Antimicrobial evaluation showed reduced colony-forming units (CFU) among all experimental groups when compared to 100% β-TCP. β-TCP scaffolds augmented with Ag ions facilitate antibacterial effects while promoting osteoblast adhesion and proliferation.

Bacterial Burden Declines But Neutrophil Infiltration and Ocular Tissue Damage Persist in Experimental Staphylococcus epidermidis Endophthalmitis

Coagulase-negative staphylococci (CoNS), including Staphylococcus (S) epidermidis, are responsible for ~70% of all post-surgical endophthalmitis, a potentially blinding eye infection. However, the pathobiology of CoNS endophthalmitis is limited to epidemiological and clinical case studies with few experimental studies. Here, we report both in vitro and in vivo models to study the pathobiology of S. epidermidis endophthalmitis in mice. We found that S. epidermidis is rapidly cleared from mouse eyes, and a relatively higher dose (i.e., 107 CFU/eye) was needed to cause endophthalmitis. Our time-course study revealed that bacterial load peaked at 24 h post-infection followed by a gradual decline up to 72 h. A similar time-dependent decrease in levels of inflammatory mediators and Toll-like receptor (TLR) expression was also observed. In contrast, neutrophil infiltration continued to increase up to 72 h coinciding with significant retinal tissue damage and loss of visual function. In vitro, S. epidermidis induced the activation of various inflammatory signaling pathways (i.e., NF-kB, ERK, and P38) and the production of both cytokines and chemokines in mouse BMDMs, human RPE, and retinal Muller glia. Altogether, we show that bacterial burden is reduced in S. epidermidis endophthalmitis, while tissue damage and visual function loss continue. Thus, our study provides new insights into the pathogenesis of CoNS endophthalmitis.

IL-6 Signaling Protects Zebrafish Larvae during Staphylococcus epidermidis Infection in a Bath Immersion Model

The host immune responses to Staphylococcus epidermidis, a frequent cause of nosocomial infections, are not well understood. We have established a bath immersion model of this infection in zebrafish (Danio rerio) larvae. Macrophages play a primary role in the host immune response and are involved in clearance of infection in the larvae. S. epidermidis infection results in upregulation of tlr-2 There is marked inflammation characterized by heightened NF-κB signaling and elevation of several proinflammatory cytokines. There is rapid upregulation of il-1b and tnf-a transcripts, whereas an increase in il-6 levels is relatively more delayed. The IL-6 signaling pathway is further amplified by elevation of IL-6 signal transducer (il-6st) levels, which negatively correlates with miRNA dre-miR-142a-5p. Enhanced IL-6 signaling is protective to the host in this model as inhibition of the signaling pathway resulted in increased mortality upon S. epidermidis infection. Our study describes the host immune responses to S. epidermidis infection, establishes the importance of IL-6 signaling, and identifies a potential role of miR-142-5p-il-6st interaction in this infection model.

Non-Native Peptides Capable of Pan-Activating the agr Quorum Sensing System across Multiple Specificity Groups of Staphylococcus epidermidis

Staphylococcus epidermidis is a leading cause of hospital-acquired infections. Traditional antibiotics have significantly reduced efficacy against this pathogen due to its ability to form biofilms on abiotic surfaces and drug resistance. The accessory gene regulator (agr) quorum sensing system is directly involved in S. epidermidis pathogenesis. Activation of agr is achieved via binding of the autoinducing peptide (AIP) signal to the extracellular sensor domain of its cognate receptor, AgrC. Divergent evolution has given rise to four agr specificity groups in S. epidermidis defined by the unique AIP sequence used by each group (AIPs-I-IV) with observed cross-group activities. As agr agonism has been shown to reduce biofilm growth in S. epidermidis, the development of pan-group activators of the agr system is of interest as a potential antivirulence strategy. To date, no synthetic compounds have been identified that are capable of appreciably activating the agr system of more than one specificity group of S. epidermidis or, to our knowledge, of any of the other Staphylococci. Here, we report the characterization of the structure-activity relationships for agr agonism by S. epidermidis AIP-II and AIP-III and the application of these new SAR data and those previously reported for AIP-I for the design and synthesis of the first multigroup agr agonists. These non-native peptides were capable of inducing the expression of critical biofilm dispersal agents (i.e., phenol-soluble modulins) in cell culture and represent new tools to study the role of quorum sensing in S. epidermidis infections.

Multimodal Analysis of the Tissue Response to a Bone-Anchored Hearing Implant: Presentation of a Two-Year Case Report of a Patient With Recurrent Pain, Inflammation, and Infection, Including a Systematic Literature Review

Osseointegration is a well-established concept used in applications including the percutaneous Bone-Anchored Hearing System (BAHS) and auricular rehabilitation. To date, few retrieved implants have been described. A systematic review including cases where percutaneous bone-anchored implants inserted in the temporal bone were retrieved and analyzed was performed. We also present the case of a patient who received a BAHS for mixed hearing loss. After the initial surgery, several episodes of soft tissue inflammation accompanied by pain were observed, leading to elective abutment removal 14 months post-surgery. Two years post-implantation, the implant was removed due to pain and subjected to a multiscale and multimodal analysis: microbial DNA using molecular fingerprinting, gene expression using quantitative real-time polymerase chain reaction (qPCR), X-ray microcomputed tomography (micro-CT), histology, histomorphometry, backscattered scanning electron microscopy (BSE-SEM), Raman spectroscopy, and fluorescence in situ hybridization (FISH). Evidence of osseointegration was provided via micro-CT, histology, BSE-SEM, and Raman spectroscopy. Polymicrobial colonization in the periabutment area and on the implant, including that with Staphylococcus aureus and Staphylococcus epidermidis, was determined using a molecular analysis via a 16S-23S rDNA interspace [IS]-region-based profiling method (IS-Pro). The histology suggested bacterial colonization in the skin and in the peri-implant bone. FISH confirmed the localization of S. aureus and coagulase-negative staphylococci in the skin. Ten articles (54 implants, 47 patients) met the inclusion criteria for the literature search. The analyzed samples were either BAHS (35 implants) or bone-anchored aural epitheses (19 implants) in situ between 2 weeks and 8 years. The main reasons for elective removal were nonuse/changes in treatment, pain, or skin reactions. Most samples were evaluated using histology, demonstrating osseointegration, but with the absence of bone under the implants’ proximal flange. Taken together, the literature and this case report show clear evidence of osseointegration, despite prominent complications. Nevertheless, despite implant osseointegration, chronic pain related to the BAHS may be associated with a chronic bacterial infection and raised inflammatory response in the absence of macroscopic signs of infection. It is suggested that a multimodal analysis of peri-implant health provides possibilities for device improvements and to guide diagnostic and therapeutic strategies to alleviate the impact of complications.

Interplay of Staphylococcal and Host Proteases Promotes Skin Barrier Disruption in Netherton Syndrome

Netherton syndrome (NS) is a monogenic skin disease resulting from loss of function of lymphoepithelial Kazal-type-related protease inhibitor (LEKTI-1). In this study we examine if bacteria residing on the skin are influenced by the loss of LEKTI-1 and if interaction between this human gene and resident bacteria contributes to skin disease. Shotgun sequencing of the skin microbiome demonstrates that lesional skin of NS subjects is dominated by Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis). Isolates of either species from NS subjects are able to induce skin inflammation and barrier damage on mice. These microbes promote skin inflammation in the setting of LEKTI-1 deficiency due to excess proteolytic activity promoted by S. aureus phenol-soluble modulin α as well as increased bacterial proteases staphopain A and B from S. aureus or EcpA from S. epidermidis. These findings demonstrate the critical need for maintaining homeostasis of host and microbial proteases to prevent a human skin disease.

Staphylococcus epidermidis protease EcpA can be a deleterious component of the skin microbiome in atopic dermatitis

BACKGROUND

Staphylococcus aureus and Staphylococcus epidermidis are the most abundant bacteria found on the skin of patients with atopic dermatitis (AD). S aureus is known to exacerbate AD, whereas S epidermidis has been considered a beneficial commensal organism.

OBJECTIVE

In this study, we hypothesized that S epidermidis could promote skin damage in AD by the production of a protease that damages the epidermal barrier.

METHODS

The protease activity of S epidermidis isolates was compared with that of other staphylococcal species. The capacity of S epidermidis to degrade the barrier and induce inflammation was examined by using human keratinocyte tissue culture and mouse models. Skin swabs from atopic and healthy adult subjects were analyzed for the presence of S epidermidis genomic DNA and mRNA.

RESULTS

S epidermidis strains were observed to produce strong cysteine protease activity when grown at high density. The enzyme responsible for this activity was identified as EcpA, a cysteine protease under quorum sensing control. EcpA was shown to degrade desmoglein-1 and LL-37 in vitro, disrupt the physical barrier, and induce skin inflammation in mice. The abundance of S epidermidis and expression of ecpA mRNA were increased on the skin of some patients with AD, and this correlated with disease severity. Another commensal skin bacterial species, Staphylococcus hominis, can inhibit EcpA production by S epidermidis.

CONCLUSION

S epidermidis has commonly been regarded as a beneficial skin microbe, whereas S aureus has been considered deleterious. This study suggests that the overabundance of S epidermidis found on some atopic patients can act similarly to S aureus and damage the skin by expression of a cysteine protease.

Performance of penicillinase detection tests in Staphylococcus epidermidis: comparison of different phenotypic methods

Background

Staphylococcus epidermidis is the leading coagulase negative staphylococci (CoNS) species associated with healthcare associated infections. In order to de-escalate antimicrobial therapy, isolates of S. epidermidis lacking the blaZ gene should be eligible for targeted antimicrobial therapy. However, testing the susceptibility of coagulase negative staphylococci (CoNS) to penicillin G is no longer recommended by EUCAST, given the low performances for penicillinase detection in CoNS. The objective of this work was to determine a phenotypic method with high performance for detecting penicillinase production in S. epidermidis.

Results

Four techniques for the detection of penicillinase production (disk diffusion, zone edge test, nitrocefin test, Minimal Inhibitory Concentration (MIC) by automated system Vitek2®) were evaluated on 182 S. epidermidis isolates, using identification of blaZ gene by PCR as the reference method. The performance of the methods for penicillinase detection was compared by the sensitivity, the specificity, the negative predictive value and the positive predictive value, and with Cohen’s kappa statistical test. Among the 182 S. epidermidis included in this study, 55 carried the blaZ gene. The nitrocefin test, characterized by a poor sensitivity (91%), was therefore excluded from S. epidermidis penicillinase detection. The algorithm proposed here for the penicillinase detection in S. epidermidis involved two common antimicrobial susceptibility techniques: disk diffusion method and MIC by Vitek2® system. Disk diffusion method, interpreted with a 26 mm breakpoint for penicillin G, was associated with a high sensitivity (98%) and specificity (100%). This method was completed with zone edge test for S. epidermidis with penicillin G diameter from 26 to 35 mm (sensitivity of 98%). The Vitek2® system is associated with a low sensitivity (93%) and a high specificity (99%) This low sensitivity is associated with false negative results, in isolates with 0.12 mg/L Penicillin G MIC values and blaZ positive. Thus for penicillin G MIC of 0.06 mg/L or 0.12 mg/L, a second step with disc diffusion method is suggested.

Conclusions

According to our results, the strategy proposed here allows the interpretation of penicillin G susceptibility in S. epidermidis isolates, with an efficient detection of penicillin G resistance.

Viral adaption of staphylococcal phage: A genome-based analysis of the selective preference based on codon usage Bias

Given the high therapeutic value of the staphylococcal phage, the genome co-evolution of the phage and the host has gained great attention. Though the genome-wide AT richness in staphylococcal phages has been well-studied with nucleotide usage bias, here we proved that host factor, lifestyle and taxonomy are also important factors in understanding the phage nucleotide usages bias using information entropy formula. Such correlation is especially prominent when it comes to the synonymous codon usages of staphylococcal phages, despite the overall scattered codon usage pattern represented by principal component analysis. This strong relationship is explained by nucleotide skew which testified that the usage biases of nucleotide at different codon positions are acting on synonymous codons. Therefore, our study reveals a hidden relationship of genome evolution with host limitation and phagic phenotype, providing new insight into phage genome evolution at genetic level.

Effect of Ethanol Extracts of Propolis (EEPs) against Staphylococcal Biofilm-Microscopic Studies

Staphylococci growing in the form of biofilm exhibit high resistance to a plethora of antibiotics. The aim of the study was to assess the influence of ethanolic extract of propolis (EEPs) on S. epidermidis ATCC 35984 biofilm using fluorescent microscopy. Propidium iodide (PI) and SYTO 9 were used for differentiation of live and dead cells, and calcofluor white was used to stain the extracellular matrix, the self-produced extracellular polymeric substances (EPS). The outcomes of the research confirm the promising potential of EEPs for eradication of staphylococcal biofilm. However, its activity cannot be classified as fully satisfactory, either in terms of the effectiveness of elimination of bacterial cells or disturbing the EPS structure. A two or even four times higher concentration of EEPs compared to MIC (Minimum Inhibitory Concentration) against planktonic cells (128 µg/mL) was necessary for effective (estimated for 90%) elimination of living cells from the biofilm structure. Unfortunately, even at that concentration of EEPs, the extracellular matrix was only partially disturbed and effectively protected the residual population of living cells of S. epidermidis ATCC 35984. In our opinion, a combination of EEPs with agents disrupting components of EPS, e.g., proteases, lysines, or enzymes degrading extracellular DNA or PIA (polysaccharide intercellular adhesin).

Microbiological Air Quality in a Highschool Gym Located in an Urban Area of Southern Poland—Preliminary Research

The benefits of regular exercise include improved physical and mental health. The school gym is a particular micro-environment where students perform intensive physical training. The question is if there is an increased risk of microbiological contamination. This preliminary work studied the exposure of students to bacterial aerosol (BA) in a highschool gym located in an urban area of Southern Poland. A sampling of BA was undertaken with an Andersen six-stage impactor (ANDI). BA was identified using API (analytical profile index) tests. The BA concentrations were expressed as Colony Forming Units (CFU) per cubic metre of air. The results showed that before gym classes (BGC), the concentration of BA was 4.20 × 102 ± 49.19 CFU/m3, while during gym classes (DGC), the level of BA more than doubled (8.75 × 102 ± 121.39 CFU/m3). There was also an increase in the respirable fraction of BA (particles less than 3.3 µm). Before the start of the sports activities, respirable fraction accounted for 30% of the BA, while during physical education classes, this share increased to over 80%. Identification of BA species showed that the dominant group of bacteria in the indoor air of the gym BGC was Gram-positive rods (61%) and for DGC it was Gram-positive cocci (81%). We detected that one bacteria strain (Corynebacterium striatum) was classified into risk group 2 (RG2) according to Directive 2000/54/EC. Additionally, multi-antibiotic resistance (MAR) showed that among the isolated airborne bacteria, the highest antibiotic resistance was demonstrated by Staphylococcus epidermis (isolated DGC) and Pseudomonas sp. (isolated BGC). The quantitative and qualitative information on microbiological air quality (MIAQ) in the school gym indicates that the actions to improve indoor physical activity spaces are recommended.

Rates of cerebrospinal fluid infection and the causative organisms following shunt procedures in Saudi Arabia. A retrospective study based on radiological findings

Objectives:

To assess the incidence of infection following various cerebrospinal fluid (CSF) shunt procedures among patients with hydrocephalus and related conditions, based on the age of the patient, and to determine the types of pathogens responsible for shunt infections.

Methods:

This retrospective single center study reviewed the records of patients with culture-confirmed CSF shunt infection diagnosed between January 2012 and December 2017. Cases without central nervous system imaging investigations were excluded.

Results:

The incidence rate of shunt-related infections was 32.2%. Among the 189 patients whose records were included, Staphylococcus epidermidis (47.5%) and Acinetobacter baumannii (18%) were the most common causative organisms. The incidence of postoperative infection was higher among those who underwent external ventricular drain procedures (65%) than among those who underwent ventriculoperitoneal shunt procedures (24%). There were no intraoperative deaths. However, the postoperative death rate was 12.2% during hospital stay (mean duration = 9 days); 2% of these deaths occurred after shunt removal.

Conclusion:

The incidence of infections after CSF shunt procedures was high in our tertiary academic hospital during the study period, compared to those reported in similar clinical settings and before developing a detailed standardized protocol for infection control. Although gram-negative organisms were the most prevalent cause of CSF infections, S. epidermidis (a gram-positive organism) was the most commonly encountered causative agent. Shunt protocols should be implemented to address perioperative shortcomings and to reduce overall mortality and morbidity.

Antibacterial, Cytocompatible, Sustainably Sourced: Cellulose Membranes with Bifunctional Peptides for Advanced Wound Dressings

Progressive antibiotic resistance is a serious condition adding to the challenges associated with skin wound treatment, and antibacterial wound dressings with alternatives to antibiotics are urgently needed. Cellulose-based membranes are increasingly considered as wound dressings, necessitating further functionalization steps. A bifunctional peptide, combining an antimicrobial peptide (AMP) and a cellulose binding peptide (CBP), is designed. AMPs affect bacteria via multiple modes of action, thereby reducing the evolutionary pressure selecting for antibiotic resistance. The bifunctional peptide is successfully immobilized on cellulose membranes of bacterial origin or electrospun fibers of plant-derived cellulose, with tight control over peptide concentrations (0.2 ± 0.1 to 4.6 ± 1.6 µg mm^-2 ). With this approach, new materials with antibacterial activity against Staphylococcus aureus (log4 reduction) and Pseudomonas aeruginosa (log1 reduction) are developed. Furthermore, membranes are cytocompatible in cultures of human fibroblasts. Additionally, a cell adhesive CBP-RGD peptide is designed and immobilized on membranes, inducing a 2.2-fold increased cell spreading compared to pristine cellulose. The versatile concept provides a toolbox for the functionalization of cellulose membranes of different origins and architectures with a broad choice in peptides. Functionalization in tris-buffered saline avoids further purification steps, allowing for translational research and multiple applications outside the field of wound dressings.

Multidrug-Resistant Staphylococcus epidermidis Ventriculostomy-Related Infection Successfully Treated by Intravenous Ceftaroline after Failure of Daptomycin Treatment

BACKGROUND

Ventriculostomy-related infection with multidrug-negative strains are challenging to treat. We report the use of new antibiotics in such a case.

CASE DESCRIPTION

We report the case of a neurosurgical intensive care unit patient who developed ventriculostomy-related infection with a multidrug-resistant Staphylococcus epidermidis. Vancomycin, recommended in such cases, was not used due to high minimal inhibitory concentrations and concerns for lack of pharmacokinetic/pharmacodynamic target attainment. Daptomycin and ceftaroline remained the only treatment options. Daptomycin was shown microbiologically ineffective after 10 treatment days, with undetectable cerebrospinal fluid (CSF) concentration. Ceftaroline, a novel beta-lactam agent to which the strain showed susceptibility, was thus used. Serum and CSF samples were assessed for antibiotic concentrations. Our results show that CSF bacterial clearance was obtained after 6 days of such treatment. Serum and CSF samplings showed low penetration ratios (2.6%-4.8%), probably due to mild inflammatory CSF profile, with CSF concentration at minimal inhibitory concentration level.

CONCLUSIONS

We observed than even in the case of mild meningeal inflammation, ceftaroline penetration in CSF, although moderate, enabled efficient bacterial clearance and clinical efficacy, in adjunction to correct ventriculoperitoneal shunt management.

The biofilm adhesion protein Aap from Staphylococcus epidermidis forms zinc-dependent amyloid fibers

The skin-colonizing commensal bacterium Staphylococcus epidermidis is a leading cause of hospital-acquired and device-related infections. Its pathogenicity in humans is largely due to its propensity to form biofilms, surface-adherent bacterial accumulations that are remarkably resistant to chemical and physical stresses. Accumulation-associated protein (Aap) from S. epidermidis has been shown to be necessary and sufficient for mature biofilm formation and catheter infection. Aap contains up to 17 tandem B-repeat domains, capable of zinc-dependent assembly into twisted, rope-like intercellular filaments in the biofilm. Using microscopic and biophysical techniques, we show here that Aap B-repeat constructs assemble further into zinc-dependent functional amyloid fibers. We observed such amyloid fibers by confocal microscopy during both early and late stages of S. epidermidis biofilm formation, and we confirmed that extracellular fibrils from these biofilms contain Aap. Unlike what has been observed for amyloidogenic biofilm proteins from other bacteria, which typically use chaperones or initiator proteins to initiate amyloid assembly, our findings indicate that Aap from S. epidermidis requires Zn²⁺ as a catalyst that drives amyloid fiber formation, similar to many mammalian amyloid-forming proteins that require metals for assembly. This work provides detailed insights into S. epidermidis biofilm formation and architecture that improve our understanding of persistent staphylococcal infections.

Effects of staphylococcal infection and aseptic inflammation on bone mass and biomechanical properties in a rabbit model

Background/objective

Orthopaedic implants are important devices aimed at relieving pain and improving mobility. Staphylococcal infection and aseptic loosening are two common events associated with inflammatory osteolysis that lead to implant failures. Bone mass and biomechanical properties are important indicators that could influence patient outcomes after revision surgery. However, the dynamics of bacterial infections and their influence on bone mass and biomechanical properties remain unclear. Hence, in this study, we developed rabbit aseptic inflammation and staphylococcal infection models to determine the effects of coagulase-positive and coagulase-negative bacterial infection, as well as aseptic inflammation, on the mass and biomechanical properties of the bone.

Methods

Sixty New Zealand white rabbits were randomly assigned to 6 groups, and each group had 10 rabbits. The medullary cavities in rabbits of each group were injected with phosphate-buffered saline (100 ​μL), titanium (Ti)-wear particles (300 μg/100 ​μL), a low concentration of Staphylococcus epidermidis (10⁵/100 ​μL), a high concentration of S. epidermidis (10⁸/100 ​μL), a low concentration of Staphylococcus aureus (10⁵/100 ​μL), and a high concentration of S. aureus (10⁸/100 ​μL), respectively. At four and eight weeks after surgery, the rabbits were sacrificed, and the tibias on the surgical side were analysed via histopathology, microcomputed tomography, and nanoindentation testing.

Results

Histopathological analysis demonstrated that inflammatory responses and bacterial loads caused by high concentrations of staphylococcal infections, particularly coagulase-positive staphylococci, are more detrimental than low concentrations of bacterial infection and Ti-wear particles. Meanwhile, microcomputed tomography and nanoindentation testing showed that high concentrations of S. aureus caused the highest loss in bone mass and most biomechanical function impairment in rabbits experiencing aseptic inflammation and staphylococcal infections.

Conclusions

Inflammatory osteolysis caused by a high concentration of coagulase-positive staphylococci is significantly associated with low bone mass and impaired biomechanical properties.

The translational potential of this article

It is necessary to obtain an overall assessment of the bone mass and biomechanical properties before revision surgery, especially when S. aureus infection is involved. In addition, a better understanding of these two parameters might help develop a reasonable treatment regimen and reduce the risk of adverse events after revision surgery.

Association between daptomycin susceptibility and teicoplanin resistance in Staphylococcus epidermidis

Staphylococcus epidermidis infections are a common occurrence in hospitals, particularly in catheter-related bloodstream and surgical site infections and infective endocarditis. Higher daptomycin minimum inhibitory concentration (MIC) values may be associated with daptomycin treatment failure among patients with S. epidermidis infections. We therefore conducted a retrospective cohort study to determine the predictive value of daptomycin susceptibility. A retrospective study was undertaken in 1,337 patients with S. epidermidis infections. Data were collected from 1 January 2013 to 31 December 2016 at Ehime University Hospital, and included the following clinicopathological factors for evaluation: age, sex, resistance to vancomycin or teicoplanin, and history of antimicrobial therapy. Multiple analysis was performed using logistic regression to identify factors that independently and significantly affected the daptomycin resistance. Daptomycin-resistant S. epidermidis was identified in 38 (2.8%) patients. According to the multiple analysis, only higher MIC values (≥16 mg/L) for teicoplanin (P < 0.0001) were independently associated with an increased risk of developing daptomycin resistance. In conclusion, higher teicoplanin MIC values may predict resistance to daptomycin treatment in S. epidermidis infections.

Time-variable expression levels of mazF, atlE, sdrH, and bap genes during biofilm formation in Staphylococcus epidermidis

Staphylococcus epidermidis is an opportunistic pathogen causing infections related to the usage of implants and medical devices. Pathogenicity of this microorganism is mainly linked to its capability to form biofilm structures. Biofilm formation vastly depends on several factors including different proteins. We studied the expression levels of three proteins including SdrH, Bap, AtlE, and MazF at different time intervals during the course of biofilm formation. In this study, a catheter-derived S. epidermidis isolate with strong ability of biofilm formation was selected. PCR assay was used to detect sdrH, bap, atlE, and mazF genes in this isolate. Real-time PCR was used to determine the expression levels of these genes after 4, 8, and 20 h during the course of biofilm formation. The studied genes showed different expression levels at different time intervals during biofilm formation by real-time PCR method. Expression levels of atlE and sdrH genes were the highest at 4 h, whereas bap gene showed the highest expression level at 8 h during the course of biofilm formation. In addition, the expression level of mazF gene peaked at 4 h and then progressively decreased at 8 and 20 h. Our results suggest the importance of AtlE, SdrH, and MazF proteins in the establishment and development of the biofilm structure. In addition, our results showed the important role of protein Bap in the accumulation of biofilm structure. Future studies are required to understand the exact role of MazF in the process of biofilm formation.

A microscopic analysis of single-use versus multi-use phacoemulsification tubing in maintaining sterility and patient safety

Background: The Pietermaritzburg (PMB) complex in South Africa does not have a uniform protocol regarding reuse of phacoemulsification tubing. Each hospital in the complex has its own guideline, based on manufacturer recommendation and cost-saving measures. There is no definitive scientific evidence proving that reusing phaco tubing will harm patients.Aim: To assess if phacoemulsification tubing remains sterile during sequential phacoemulsification.Setting: The study was conducted at Edendale Hospital and Greys Hospital in PMB. Greys Hospital has a single-use policy and at Edendale policy, multi-use of tubings is allowed.Methods: This was an observational descriptive prospective study observed over 4 months. Routine phacoemulsification was carried out at each hospital as per hospital guidelines. At the end of the surgery, the tips of the tubing were cut off, placed in a standard specimen container and sent to the laboratory for culture and microscopy. Results were compared and two unused tubings were also analysed as controls.Results: A total of 26 single-use tubings were analysed and it was found that 46.2% grew no organisms; 19.2% grew Bacillus species; other microorganisms were in less than 1% of tubings. A total of 41 multiple-use tubings were sent for analysis. Forty one and a half percent grew no organisms; 17.1% tubings grew Bacillus species. Other microorganisms were found in less than 5% of tubings. Unused tubings did not grow any microorganism.Conclusion: A p value less than 0.05% was accepted as statistically significant. Comparing the two hospitals, tubings which grew no organisms were 46.2% (single-use) versus 41.5% (multiple-use). This gives a statistically non-significant p value of 0.70. Tubings which grew Bacillus species were 19.2% (single-use) versus 17.1% (multiple-use) (p = 0.83). Other microorganisms also showed a p value of 0.76. This implies that phacoemulsification tubing is significantly contaminated after just one use. Although no statistical difference was found between the two groups, a contamination rate of over 40% is of great concern. There are contributing factors which may have influenced this result. In our setting, phaco tubing does not seem to remain sterile after cataract surgery. Further research needs to be carried out in order to gain more insight into patient safety.

Back to Basics: Could the Preoperative Skin Antiseptic Agent Help Prevent Biofilm-Related Capsular Contracture?

BACKGROUND

Capsular contracture (CC) has remained an unresolved issue throughout history. Strong evidence focuses on bacterial biofilm as its main source. A literature review revealed that more than 90% of bacteria found in capsules and implants removed from patients with Baker grade III-IV CC belong to the resident skin microbiome (Staphylococcus epidermidis, predominant microorganism). The use of an adequate preoperative skin antiseptic may be a critical step to minimize implant contamination and help prevent biofilm-related CC.

OBJECTIVES

The authors sought to compare the effect of 2 different antiseptic skin preparations: povidone-iodine (PVP-I) vs chlorhexidine gluconate (CHG) on CC proportions after primary breast augmentation through a periareolar approach.

METHODS

In June of 2014, The Society for Healthcare Epidemiology of America proposed to use CHG for preoperative skin preparation in the absence of alcohol-containing antiseptic agents as strategy to prevent surgical site infection. The clinical safety committee of a surgical center in Colombia decided to change PVP-I to CHG for surgical site preparation thereafter. The medical records of 63 patients who underwent to primary breast augmentation through a periareolar approach during 2014 were reviewed. In the first 6 months PVP-I was used in 32 patients, and later CHG was employed in 31 patients.

RESULTS

Pearson's chi-squared test to compare CC proportions between subgroups showed a statistically significant difference. The CC proportion was higher for patients who had antisepsis with PVP-I. CC was absent when CHG was employed.

CONCLUSIONS

CHG as preoperative skin antiseptic for primary breast augmentation surgery was more effective than PVP-I to help prevent biofilm-related CC.

LEVEL OF EVIDENCE: 3

Differences in distribution of MLS antibiotics resistance genes in clinical isolates of staphylococci belonging to species: S. epidermidis, S. hominis, S. haemolyticus, S. simulans and S. warneri

Background

Macrolides and lincosamides are two leading types of antibiotics commonly used in therapies. The study examines the differences in resistance to these antibiotics and their molecular bases in S. epidermidis as well as in rarely isolated species of coagulase-negative staphylococci such as S. hominis, S. haemolyticus, S. warneri and S. simulans. The isolates were tested for the presence of the erm(A), erm(B), erm(C), lnu(A), msr(A), msr(B), mph(C), ere(A) and ere(B) genes. Phenotypic resistance to methicillin and mecA presence were also determined.

Results

The MLS_B resistance mechanism was phenotypically found in isolates of species included in the study. The most prevalent MLS_B resistance mechanism was observed in S. hominis, S. haemolyticus and S. epidermidis isolates mainly of the MLS_B resistance constitutive type. Macrolide, lincosamide and streptogramin B resistance genes were rarely detected in isolates individually. The erm(B), ere(A) and ere(B) genes were not found in any of the strains. The erm(A) gene was determined only in four strains of S. epidermidis and S. hominis while lnu(A) was seen in eight strains (mainly in S. hominis). The erm(C) gene was present in most of S. epidermidis strains and predominant in S. hominis and S. simulans isolates. The examined species clearly differed between one another in the repertoire of accumulated genes.

Conclusions

The presence of genes encoding the MLS_B resistance among CoNS strains demonstrates these genes’ widespread prevalence and accumulation in opportunistic pathogens that might become gene reservoir for bacteria with superior pathogenic potential.

Crystal Chemistry and Antibacterial Properties of Cupriferous Hydroxyapatite

Copper-doped hydroxyapatite (HA) of nominal composition Ca₁₀(PO₄)₆[Cu_x(OH)_2-2xO_x] (0.0 ≤ x ≤ 0.8) was prepared by solid-state and wet chemical processing to explore the impact of the synthesis route and mode of crystal chemical incorporation of copper on the antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) strains. Apatites prepared by solid-state reaction showed unit cell volume dilation from 527.17 ų for copper-free HA to 533.31 ų for material of the putative composition Ca₁₀(PO₄)₆[Cu_0.8(OH)_0.4O_0.8] consistent with Cu⁺ insertion into the [001] hydroxyapatite channel. This was less pronounced (528.30 ų to 529.3 ų) in the corresponding wet chemical synthesised products, suggesting less complete Cu tunnel incorporation and partial tenancy of Cu in place of calcium. X-ray absorption spectroscopy suggests fast quenching is necessary to prevent oxidation of Cu⁺ to Cu²⁺. Raman spectroscopy revealed an absorption band at 630 cm⁻¹ characteristic of symmetric O-Cu⁺-O units tenanted in the apatite channel while solid-state ³¹P magic-angle-spinning nuclear magnetic resonance (MAS NMR) supported a vacancy-Cu⁺ substitution model within the apatite channel. The copper doping strategy increases antibacterial efficiency by 25% to 55% compared to undoped HA, with the finer particle sizes and greater specific surface areas of the wet chemical material demonstrating superior efficacy.

Variation in Mutant Prevention Concentrations

Objectives:Understanding how phenotypic traits vary has been a longstanding goal of evolutionary biologists. When examining antibiotic-resistance in bacteria, it is generally understood that the minimum inhibitory concentration (MIC) has minimal variation specific to each bacterial strain-antibiotic combination. However, there is a less studied resistance trait, the mutant prevention concentration (MPC), which measures the MIC of the most resistant sub-population. Whether and how MPC varies has been poorly understood. Here, we ask a simple, yet important question: How much does the MPC vary, within a single strain-antibiotic association? Using a Staphylococcus species and five antibiotics from five different antibiotic classes—ciprofloxacin, doxycycline, gentamicin, nitrofurantoin, and oxacillin—we examined the frequency of resistance for a wide range of concentrations per antibiotic, and measured the repeatability of the MPC, the lowest amount of antibiotic that would ensure no surviving cells in a 10¹⁰ population of bacteria.

Results: We found a wide variation within the MPC and distributions that were rarely normal. When antibiotic resistance evolved, the distribution of the MPC changed, with all distributions becoming wider and some multi-modal.

Conclusion: Unlike the MIC, there is high variability in the MPC for a given bacterial strain-antibiotic combination.

Competition/antagonism associations of biofilm formation among Staphylococcus epidermidis Agr groups I, II, and III

Staphylococci have quorum-sensing (QS) systems that enable cell-to-cell communication, as well as the regulation of numerous colonization and virulence factors. The accessory gene regulator (Agr) operon is one of the Staphylococcus genus QS systems. Three groups (I, II, and III) are present in Staphylococcus epidermidis Agr operon. To date, it is unknown whether Agr groups can interact symbiotically during biofilm development. This study analyzed a symbiotic association among Agr groups during biofilm formation in clinical and commensal isolates. Different combinations among Agr group isolates was used to study biofilm formation in vitro and in vivo (using a mouse catheter-infection model). The analysis of Agr groups were also performed from samples of human skin (head, armpits, and nostrils). Different predominant coexistence was found within biofilms, suggesting symbiosis type. In vitro, Agr I had a competition with Agr II and Agr III. Agr II had a competition with Agr III, and Agr II was an antagonist to Agr I and III when the three strains were combined. In vivo, Agr II had a competition to Agr I, but Agr I and II were antagonists to Agr III. The associations found in vitro and in vivo were also found in different sites of the skin. Besides, other associations were observed: Agr III antagonized Agr I and II, and Agr III competed with Agr I and Agr II. These results suggest that, in S. epidermidis, a symbiotic association of competition and antagonism occurs among different Agr groups during biofilm formation.

Disease-associated genotypes of the commensal skin bacterium Staphylococcus epidermidis

Some of the most common infectious diseases are caused by bacteria that naturally colonise humans asymptomatically. Combating these opportunistic pathogens requires an understanding of the traits that differentiate infecting strains from harmless relatives. Staphylococcus epidermidis is carried asymptomatically on the skin and mucous membranes of virtually all humans but is a major cause of nosocomial infection associated with invasive procedures. Here we address the underlying evolutionary mechanisms of opportunistic pathogenicity by combining pangenome-wide association studies and laboratory microbiology to compare S. epidermidis from bloodstream and wound infections and asymptomatic carriage. We identify 61 genes containing infection-associated genetic elements (k-mers) that correlate with in vitro variation in known pathogenicity traits (biofilm formation, cell toxicity, interleukin-8 production, methicillin resistance). Horizontal gene transfer spreads these elements, allowing divergent clones to cause infection. Finally, Random Forest model prediction of disease status (carriage vs. infection) identifies pathogenicity elements in 415 S. epidermidis isolates with 80% accuracy, demonstrating the potential for identifying risk genotypes pre-operatively.

Antibacterial activity of Manuka honey and its components: An overview

The importance of honey for medicinal purposes is well documented in some of the world's oldest literature. Honey is well known and studied for its antimicrobial properties. The medicinal properties in honey originate from the floral source used by bees. Manuka honey is a dark monofloral honey rich in phenolic content, and currently it is gaining much attention for its antimicrobial activity. Researchers have found that honey is effective against a wide range of pathogens. The antibacterial potency of Manuka honey was found to be related to the Unique Manuka Factor (UMF) rating, which is correlated with the methylglyoxal and total phenols content. It is reported that different types of Manuka honey have differing effects and Gram-negative bacteria are more resistant than Gram-positive bacteria. Bacterial resistance to honey as antimicrobial agent has yet to be identified, possibly due to the presence of a complex mixture of methylglyoxal and other components. Honey is also reported to alter a bacterium's shape and size through septal ring alteration, which affects cell morphology and growth. Research has shown that Manuka honey of different UMF values has medicinal properties of interest and it can be beneficial when used as a combination treatment with other antimicrobial agents.

Simple and economical method for identification and speciation of Staphylococcus epidermidis and other coagulase negative Staphylococci and its validation by molecular methods

Coagulase-negative staphylococci (CoNS) have been increasingly recognized as a clinically important group of species that can cause several opportunistic nosocomial infections. There are at least 47 known species of Staphylococci and to differentiate all these species >40 biochemical tests need to be performed. The present study was able to refine the CoNS identification process by using only five tests to identify S. epidermidis from the rest and used six other tests to identify eleven other clinically significant CoNS species. A total of 242 CoNS isolates were collected from tertiary care hospitals and included in the study. The five-biochemical test scheme devised based on mathematical probability derived from a computer algorithm included fermentation of mannitol, maltose, mannose, trehalose and novobiocin susceptibility to differentiate S. epidermidis from other CoNS species. The remaining CoNS isolates other than S. epidermidis were further characterized with the help of six additional tests, which identified another eleven species. Species-specific PCR and 16SrDNA sequencing were used to confirm and validate the identification scheme. Species-specific PCR and 16SrDNA sequencing showed 100% agreement with non-divergent phenotypic test results, indicating that the five selected assays are highly specific for identifying S. epidermidis. In conclusion, this study used only 11 tests to identify most of the clinically significant CoNS that can reduce cost and time. This scheme is easy to perform in any laboratory with basic resources, the results of this study were validated using more accurate molecular methods such as PCR and 16S rDNA typing to confirm the utility of the proposed scheme.

Immune Evasion Mechanisms of Staphylococcus epidermidis Biofilm Infection

The primary virulence factor of the skin commensal and opportunistic pathogen, Staphylococcus epidermidis, is the ability to form biofilms on surfaces of implanted materials. Much of this microorganism’s pathogenic success has been attributed to its ability to evade the innate immune system. The primary defense against S. epidermidis biofilm infection consists of complement activation, recruitment and subsequent killing of the pathogen by effector cells. Among pathogen-derived factors, the biofilm exopolysaccharide polysaccharide intercellular adhesion (PIA), as well as the accumulation-associated protein (Aap), and the extracellular matrix binding protein (Embp) have been shown to modulate effector cell-mediated killing of S. epidermidis. Phenol-soluble modulins (PSMs) constitute the only class of secreted toxins by S. epidermidis, at least one type of which (PSMδ) possesses strong cytolytic properties toward leukocytes. However, through selective production of non-cytolytic subtypes of PSMs, S. epidermidis is able to maintain a low inflammatory infection profile and avoid eradication by the host immune system. Taken together, our emerging understanding of the mechanisms behind immune modulation by S. epidermidis elucidates the microorganism’s success in the initial colonization of device surfaces as well as the maintenance of a chronic and indolent course of biofilm infection.

Time-Dependent Effects of Rifampicin on Staphylococcal Biofilms

Objective

To test the time-dependent effects of rifampicin on established biofilms of Staphylococcus epidermidis isolated from patients with cardiac implant infections and catheter-related bacteremia.

Methods

Biofilms were grown in microtiter plates for 24 hours, dyed and stained with crystal violet. The mean optical density (OD) was used for quantification. The OD ratio (ODr = OD of the treated biofilm/OD of the untreated biofilm) was used to measure changes in the thickness of the biofilms over the time. Biofilms were incubated with rifampicin (0.6 mg/mL) for 1, 5, 15, 30 and 60 minutes. Unstained biofilms were sonicated and plated on Columbia agar for time-kill curves.

Results

The incubation of the biofilms with rifampicin led to a significant reduction of the OD of the biofilms within 1 minute (ODr baseline: 1; ODr 1 min: 0.333 ± 0.131) (p<0.001). With regard to bacterial killing, rifampicin reduced the mean log count, but viable bacteria were still grown from biofilms in 13 out of 28 isolates despite MIC values < 0.01 mg/L.

Conclusions

In conclusion, our results confirm that rifampicin at a concentration of 1.2 mg/mL immediately reduces established biofilms formed by S. epidermidis although it is not bactericidal despite very low MICs at planktonic conditions.

Microbiology and Antimicrobial Therapy for Diabetic Foot Infections

In addition to being the prime factor associated with amputation, diabetic foot infections (DFIs) are associated with major morbidity, increasing mortality, and reduced quality of life. The choice of appropriate antibiotics is very important in order to reduce treatment failure, antimicrobial resistance, adverse events, and costs. We reviewed articles on microbiology and antimicrobial therapy and discuss antibiotic selection in Korean patients with DFIs. Similar to Western countries, Staphylococcus aureus is the most common pathogen, with Streptococcus, Enterococcus, Enterobacteriaceae and Pseudomonas also prevalent in Korea. It is recommended that antibiotics are not prescribed for clinically uninfected wounds and that empirical antibiotics be selected based on the clinical features, disease severity, and local antimicrobial resistance patterns. Narrow-spectrum oral antibiotics can be administered for mild infections and broad-spectrum parenteral antibiotics should be administered for some moderate and severe infections. In cases with risk factors for methicillin-resistant S. aureus or Pseudomonas, empirical antibiotics to cover each pathogen should be considered. The Health Insurance Review and Assessment Service standards should also be considered when choosing empirical antibiotics. In Korea, nationwide studies need to be conducted and DFI guidelines should be developed.

Silver doped resorbable tricalcium phosphate scaffolds for bone graft applications

Bone graft procedures, in particular maxillofacial repair, account for half of the orthopedic procedures done in the US each year. Infection is a major issue in surgery, and should be of primary concern when engineering biomaterials. Silver is of renewed importance today, as it has the ability to potentiate antibiotics against resistant bacterial strains. In order to reduce long term infection risks, it is necessary for the scaffold to maintain a silver ion release for the length of the healing process. In this study, silver doped porous β-tricalcium phosphate (β-TCP) scaffolds were engineered using liquid porogen based method with the goal of meeting these requirements. Silver was added to the β-TCP at three different dopant levels: 0.5wt% Ag2O, 1wt% Ag2O and 2wt% Ag2O. Immersion in pH5 acetate buffer over a 60day period resulted in a total cumulative ion release between 32 and 54μM for dense control scaffolds, and between 80 and 90μM for porous scaffolds. Porosity increased the dissolution rate of the scaffolds by a factor of 2. Human osteoblast cell lines were grown on the scaffolds to measure cytotoxicity and cell proliferation. Porosity increased osteoconduction by doubling the cell growth, and there was no significant cytotoxic effect even for the 2wt% Ag2O, as cells were observed on all the samples. Our results showed that silver can be released over a long period without compromising the biocompatibility of the scaffolds.

Comparative Genomics Study of Staphylococcus epidermidis Isolates from Orthopedic-Device-Related Infections Correlated with Patient Outcome

Staphylococcus epidermidis has emerged as an important opportunistic pathogen causing orthopedic-device-related infections (ODRI). This study investigated the association of genome variation and phenotypic features of the infecting S. epidermidis isolate with the clinical outcome for the infected patient. S. epidermidis isolates were collected from 104 patients with ODRI. Their clinical outcomes were evaluated, after an average of 26 months, as either "cured" or "not cured." The isolates were tested for antibiotic susceptibility and biofilm formation. Whole-genome sequencing was performed on all isolates, and genomic variation was related to features associated with "cured" and "not cured." Strong biofilm formation and aminoglycoside resistance were associated with a "not-cured" outcome (P = 0.031 and P < 0.001, respectively). Based on gene-by-gene analysis, some accessory genes were more prevalent in isolates from the "not-cured" group. These included the biofilm-associated bhp gene, the antiseptic resistance qacA gene, the cassette chromosome recombinase-encoding genes ccrA and ccrB, and the IS256-like transposase gene. This study identifies biofilm formation and antibiotic resistance as associated with poor outcome in S. epidermidis ODRI. Whole-genome sequencing identified specific genes associated with a "not-cured" outcome that should be validated in future studies. (The study has been registered at ClinicalTrials.gov with identifier NCT02640937.).

Efficient Killing of Planktonic and Biofilm-Embedded Coagulase-Negative Staphylococci by Bactericidal Protein P128

Coagulase-negative staphylococci (CoNS) are the major causative agents of foreign-body-related infections, including catheter-related bloodstream infections. Because of the involvement of biofilms, foreign-body-related infections are difficult to treat. P128, a chimeric recombinant phage-derived ectolysin, has been shown to possess bactericidal activity on strains of Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA). We tested the killing potential of P128 on three clinically significant species of CoNS, S. epidermidis, S. haemolyticus, and S. lugdunensis, under a variety of physiological conditions representing growing and nongrowing states. The MIC₉₀ and minimum bactericidal concentration at which 90% of strains tested are killed (MBC₉₀) of P128 on 62 clinical strains of CoNS were found to be 16 and 32 μg/ml (0.58 and 1.16 μM), respectively, demonstrating the bactericidal nature of P128 on CoNS strains. Serum showed a potentiating effect on P128 inhibition, as indicated by 4- to 32-fold lower MIC values observed in serum. P128 caused a rapid loss of viability in all CoNS strains tested. Persisters of CoNS that were enriched in the presence of vancomycin or daptomycin were killed by P128 at 1× the MIC in a rapid manner. Low concentrations of P128 caused a 2- to 5-log reduction in CFU in stationary-phase or poorly metabolizing CoNS cultures. P128 at low concentrations eliminated CoNS biofilms in microtiter plates and on the surface of catheters. Combinations of P128 and standard-of-care (SoC) antibiotics were highly synergistic in inhibiting growth in preformed biofilms. Potent activity on planktonic cells, persisters, and biofilms of CoNS suggests that P128 is a promising candidate for the clinical development of treatments for foreign-body-related and other CoNS infections.

Cleanliness in context: reconciling hygiene with a modern microbial perspective

The concept of hygiene is rooted in the relationship between cleanliness and the maintenance of good health. Since the widespread acceptance of the germ theory of disease, hygiene has become increasingly conflated with sterilization. In reviewing studies across the hygiene literature (most often hand hygiene), we found that nearly all studies of hand hygiene utilize bulk reduction in bacterial load as a proxy for reduced transmission of pathogenic organisms. This treatment of hygiene may be insufficient in light of recent microbial ecology research, which has demonstrated that humans have intimate and evolutionarily significant relationships with a diverse assemblage of microorganisms (our microbiota). The human skin is home to a diverse and specific community of microorganisms, which include members that exist across the ecological spectrum from pathogen through commensal to mutualist. Most evidence suggests that the skin microbiota is likely of direct benefit to the host and only rarely exhibits pathogenicity. This complex ecological context suggests that the conception of hygiene as a unilateral reduction or removal of microbes has outlived its usefulness. As such, we suggest the explicit definition of hygiene as "those actions and practices that reduce the spread or transmission of pathogenic microorganisms, and thus reduce the incidence of disease."