Nucleotides as Bacterial Second Messengers.

In addition to comprising monomers of nucleic acids, nucleotides have signaling functions and act as second messengers in both prokaryotic and eukaryotic cells. The most common example is cyclic AMP (cAMP). Nucleotide signaling is a focus of great interest in bacteria. Cyclic di-AMP (c-di-AMP), cAMP, and cyclic di-GMP (c-di-GMP) participate in biological events such as bacterial growth, biofilm formation, sporulation, cell differentiation, motility, and virulence. Moreover, the cyclic-di-nucleotides (c-di-nucleotides) produced in pathogenic intracellular bacteria can affect eukaryotic host cells to allow for infection. On the other hand, non-cyclic nucleotide molecules pppGpp and ppGpp are alarmones involved in regulating the bacterial response to nutritional stress; they are also considered second messengers. These second messengers can potentially be used as therapeutic agents because of their immunological functions on eukaryotic cells. In this review, the role of c-di-nucleotides and cAMP as second messengers in different bacterial processes is addressed.

MES SV40 Cells Are Sensitive to Lipopolysaccharide, Peptidoglycan, and Poly I:C Expressing IL-36 Cytokines.

Mesangial cells (MC) maintain the architecture and cellular communication and indirectly join in the glomerular filtration rate for the correct functioning of the glomerulus. Consequently, these cells are activated constantly in response to changes in the intraglomerular environment due to a metabolic imbalance or infection. IL-36, a member of the IL-1 family, is a cytokine that initiates and maintains inflammation in different tissues in acute and chronic pathologies, including the skin, lungs, and intestines. In the kidney, IL-36 has been described in the development of tubulointerstitial lesions, the production of an inflammatory environment, and is associated with metabolic and mesangioproliferative disorders. The participation of IL-36 in functional dysregulation and the consequent generation of the inflammatory environment by MCs in the presence of microbial stimulation is not yet elucidated. In this work, the MES SV40 cell cultures were stimulated with classical pathogen-associated molecular patterns (PAMPs), mimicking an infection by negative and positive bacteria as well as a viral infection. Lipopolysaccharide (LPS), peptidoglycan (PGN) microbial wall components, and a viral mimic poly I:C were used, and the mRNA and protein expression of the IL-36 members were assessed. We observed a differential and dose-dependent IL-36 mRNA and protein expression under LPS, PGN, and poly I:C stimulation. IL-36ß was only found when the cells were treated with LPS, while IL-36α and IL-36γ were favored by PGN and poly I:C stimulation. We suggest that the microbial components participate in the activation of MCs, leading them to the production of IL-36, in which a specific member may participate in the origin and maintenance of inflammation in the glomerular environment that is associated with infections.

Low Concentration of the Neutrophil Proteases Cathepsin G, Cathepsin B, Proteinase-3 and Metalloproteinase-9 Induce Biofilm Formation in Non-Biofilm-Forming Staphylococcus epidermidis Isolates.

Neutrophils play a crucial role in eliminating bacteria that invade the human body; however, cathepsin G can induce biofilm formation in a non-biofilm-forming Staphylococcus epidermidis 1457 strain, suggesting that neutrophil proteases may be involved in biofilm formation. Cathepsin G, cathepsin B, proteinase-3, and metalloproteinase-9 (MMP-9) from neutrophils were tested on the biofilm induction in commensal (skin isolated) and clinical non-biofilm-forming S. epidermidis isolates. From 81 isolates, 53 (74%) were aap+, icaA−, icaD− genotype, and without the capacity of biofilm formation under conditions of 1% glucose, 4% ethanol or 4% NaCl, but these 53 non-biofilm-forming isolates induced biofilm by the use of different neutrophil proteases. Of these, 62.3% induced biofilm with proteinase-3, 15% with cathepsin G, 10% with cathepsin B and 5% with MMP -9, where most of the protease-induced biofilm isolates were commensal strains (skin). In the biofilm formation kinetics analysis, the addition of phenylmethylsulfonyl fluoride (PMSF; a proteinase-3 inhibitor) showed that proteinase-3 participates in the cell aggregation stage of biofilm formation. A biofilm induced with proteinase-3 and DNAse-treated significantly reduced biofilm formation at an early time (initial adhesion stage of biofilm formation) compared to untreated proteinase-3-induced biofilm (p < 0.05). A catheter inoculated with a commensal (skin) non-biofilm-forming S. epidermidis isolate treated with proteinase-3 and another one without the enzyme were inserted into the back of a mouse. After 7 days of incubation period, the catheters were recovered and the number of grown bacteria was quantified, finding a higher amount of adhered proteinase-3-treated bacteria in the catheter than non-proteinase-3-treated bacteria (p < 0.05). Commensal non-biofilm-forming S. epidermidis in the presence of neutrophil cells significantly induced the biofilm formation when multiplicity of infection (MOI) 1:0.01 (neutrophil:bacteria) was used, but the addition of a cocktail of protease inhibitors impeded biofilm formation. A neutrophil:bacteria assay did not induce neutrophil extracellular traps (NETs). Our results suggest that neutrophils, in the presence of commensal non-biofilm-forming S. epidermidis, do not generate NETs formation. The effect of neutrophils is the production of proteases, and proteinase-3 releases bacterial DNA at the initial adhesion, favoring cell aggregation and subsequently leading to biofilm formation.

The expression of glycosyltransferases sdgA and sdgB in Staphylococcus epidermidis depends on the conditions of biofilm formation.

The Staphylococcus aureus SdrG protein is glycosylated by SdgA and SdgB for protection against its degradation by the neutrophil cathepsin G. So far, there is no information about the role of Staphylococcus epidermidis SdgA or SdgB in biofilm-forming; therefore, the focus of this work was to determine the distribution and expression of the sdrG, sdgA and sdgB genes in S. epidermidis under in vitro and in vivo biofilm conditions. The frequencies of the sdrG, sdgA and sdgB genes were evaluated by PCR in a collection of 75 isolates. Isolates were grown in dynamic (non-biofilm-forming) or static (biofilm-forming) conditions. The expression of sdrG, sdgA and sdgB was determined by RT-qPCR in cells grown under dynamic conditions (CGDC), as well as in planktonic and sessile cells from a biofilm and cells adhered to a catheter implanted in Balb/c mice. The sdrG and sdgB genes were detected in 100% of isolates, while the sdgA gene was detected in 71% of the sample (p < 0.001). CGDC did not express sdrG, sdgA and sdgB mRNAs. Planktonic and sessile cells expressed sdrG and sdgB, and the same was observed in cells adhered to the catheter. In particular, one isolate, capable of inducing a biofilm under treatment with cathepsin G, expressed sdrG and sdgB in planktonic and sessile cells and cells adhering to the catheter. This suggests that bacteria require biofilm conditions as an important factor for the transcription of the sdgA, sdgB and sdrG genes.

Staphylococcus epidermidis Controls Opportunistic Pathogens in the Nose, Could It Help to Regulate SARS-CoV-2 (COVID-19) Infection?

Staphylococcus epidermidis is more abundant in the anterior nares than internal parts of the nose, but its relative abundance changes along with age; it is more abundant in adolescents than in children and adults. Various studies have shown that S. epidermidis is the guardian of the nasal cavity because it prevents the colonization and infection of respiratory pathogens (bacteria and viruses) through the secretion of antimicrobial molecules and inhibitors of biofilm formation, occupying the space of the membrane mucosa and through the stimulation of the host's innate and adaptive immunity. There is a strong relationship between the low number of S. epidermidis in the nasal cavity and the increased risk of serious respiratory infections. The direct application of S. epidermidis into the nasal cavity could be an effective therapeutic strategy to prevent respiratory infections and to restore nasal cavity homeostasis. This review shows the mechanisms that S. epidermidis uses to eliminate respiratory pathogens from the nasal cavity, also S. epidermidis is proposed to be used as a probiotic to prevent the development of COVID-19 because S. epidermidis induces the production of interferon type I and III and decreases the expression of the entry receptors of SARS-CoV-2 (ACE2 and TMPRSS2) in the nasal epithelial cells.

The Extracellular Vesicles from the Commensal Staphylococcus Epidermidis ATCC12228 Strain Regulate Skin Inflammation in the Imiquimod-Induced Psoriasis Murine Model.

Extracellular vesicles (EVs) are evaginations of the cytoplasmic membrane, containing nucleic acids, proteins, lipids, enzymes, and toxins. EVs participate in various bacterial physiological processes. Staphylococcus epidermidis interacts and communicates with the host skin. S. epidermidis' EVs may have an essential role in this communication mechanism, modulating the immunological environment. This work aimed to evaluate if S. epidermidis' EVs can modulate cytokine production by keratinocytes in vitro and in vivo using the imiquimod-induced psoriasis murine model. S. epidermidis' EVs were obtained from a commensal strain (ATC12228EVs) and a clinical isolated strain (983EVs). EVs from both origins induced IL-6 expression in HaCaT keratinocyte cultures; nevertheless, 983EVs promoted a higher expression of the pro-inflammatory cytokines VEGF-A, LL37, IL-8, and IL-17F than ATCC12228EVs. Moreover, in vivo imiquimod-induced psoriatic skin treated with ATCC12228EVs reduced the characteristic psoriatic skin features, such as acanthosis and cellular infiltrate, as well as VEGF-A, IL-6, KC, IL-23, IL-17F, IL-36γ, and IL-36R expression in a more efficient manner than 983EVs; however, in contrast, Foxp3 expression did not significantly change, and IL-36 receptor antagonist (IL-36Ra) was found to be increased. Our findings showed a distinctive immunological profile induction that is dependent on the clinical or commensal EV origin in a mice model of skin-like psoriasis. Characteristically, proteomics analysis showed differences in the EVs protein content, dependent on origin of the isolated EVs. Specifically, in ATCC12228EVs, we found the proteins glutamate dehydrogenase, ornithine carbamoyltransferase, arginine deiminase, carbamate kinase, catalase, superoxide dismutase, phenol-soluble ß1/ß2 modulin, and polyglycerol phosphate α-glucosyltransferase, which could be involved in the reduction of lesions in the murine imiquimod-induced psoriasis skin. Our results show that the commensal ATCC12228EVs have a greater protective/attenuating effect on the murine imiquimod-induced psoriasis by inducing IL-36Ra expression in comparison with EVs from a clinical isolate of S. epidermidis.

Non-epidermidis coagulase-negative Staphylococcus isolated from farm animals can inhibit the hemagglutinating activity of Newcastle disease virus and bovine parainfluenza virus type 3.

The Embp protein of Staphylococcus epidermidis inhibits the hemagglutination of the H1N1 influenza virus and protects birds from a viral respiratory infection. Several species of Coagulase-negative Staphylococcus (CoNS) are present in the respiratory cavity, particularly in nostrils. We hypothesize that non-epidermidis CoNS found in animals can have the same function as observed in S. epidermidis. Thirty Non-epidermidis CoNS isolates were obtained from poultry, sheep, goat, pig, and dairy cow nostrils. Haemagglutination inhibition (HI) activity was assayed in bacteria-free supernatants from non-epidermidis CoNS against Newcastle disease virus (NDV) and bovine parainfluenza virus type 3 (BPIV). In 13 of the 30 strains (43.3 %), bacteria-free supernatants showed HI activity for NDV and BPIV-3. Staphylococcus xylosus supernatants from poultry (one isolate), sheep (two isolates), goat (one isolate), and dairy cow (three isolates) had the highest frequency of HI activity on NDV and BPIV-3, followed by Staphylococcus sp. supernatants from goat (one isolate), dairy cow (two isolates), and finally Staphylococcus equorum, Staphylococcus chromogens and Staphylococcus gallinarum supernatants with single isolation from poultry, pig and poultry, respectively. Nine isolates had the homologous gene to the embp gene of S. epidermidis, and it was associated with HI activity in the studied viruses. By Pulsed-field gel electrophoresis, S. xylosus isolates showed to be different clones and related to the origin of isolation and HI activity. These results demonstrate that non-epidermidis CoNS supernatants from different animals and origins have the ability of HI on NDV and BPIV-3, indicating that not only S. epidermidis has the same function.

Subacute and subchronic toxicity of microencapsulated pomegranate juice in rats and mice.

Pomegranate (Punica granatum L.) is a fruit used extensively in traditional medicine by ancient and modern cultures. Different parts of the tree and fruit, such as leaf, peel, pericarp, aril, seed, and juice contain considerable amounts of phenolic compounds with high antioxidant activities. To improve its storability, pomegranate juice was microencapsulated by spray drying. The present study evaluated microencapsulated pomegranate juice (MPJ) for toxic effects in Wistar rats and CD-1 mice to determine if MPJ can be considered safe for human consumption and used as a nutraceutical. No deaths or deleterious effects occurred when high doses of 5000 mg/kg were orally administered in rats for 14 days, indicating an absence of subacute toxicity. Similarly, 3000 mg/kg MPJ administered to CD-1 mice for 90 days did not show subchronic toxicity. In fact, MPJ resulted in lowered weight gain in both rats and mice. Cytotoxic and microbiological analyses of MPJ were also performed. MPJ did not cause any cytotoxicity in epithelial cell culture as tested using the Alamar blue assay. Additionally, histopathological analysis of kidney and liver corroborated the absence of toxicity in CD-1 mice. The microbial load of the MPJ was low, and no pathogenic bacteria were present. In conclusion, the results reported here show that high doses of MPJ are apparently innocuous in rats and mice for the 14 and 90 days investigated, respectively. Although preliminary, our results suggest that MPJ may be safe to ingest and may even have beneficial effects in reducing weight gain.

Proteomic comparison of biofilm vs. planktonic Staphylococcus epidermidis cells suggests key metabolic differences between these conditions.

Previous studies have shown that biofilm-forming bacteria are deficient in tricarboxylic acid (TCA) cycle metabolites, suggesting a relationship between these cellular processes. In this work, we compared the proteomes of planktonic vs biofilm cells from a clinical strain of Staphylococcus epidermidis using LC-MS/MS. A total of 168 proteins were identified from both growth conditions. The biofilm cells showed enrichment of proteins participating in glycolysis for the formation of pyruvate; however, the absence of TCA cycle proteins and the presence of lactate dehydrogenase, formate acetyltransferase, and acetoin reductase suggested that pyruvate was catabolized to their respective products: lactate, formate and acetoin. On the other hand, planktonic cells showed proteins participating in glycolysis and the TCA cycle, the pentose phosphate pathway, gluconeogenesis, ATP generation and the oxidative stress response. Functional networks with higher interconnection were predicted for planktonic proteins. We propose that in S. epidermidis, the relative absence of TCA cycle proteins is associated with the formation of biofilms and that lactate, formate and acetoin are the end products of partial glucose metabolism.

Assessment of the tolerance to Fe, Cu and Zn of a sulfidogenic sludge generated from hydrothermal vents sediments as a basis for its application on metals precipitation.

A paramour factor limiting metal-microorganism interaction is the metal ion concentration, and the metal precipitation efficiency driven by microorganisms is sensitive to metal ion concentration. The aim of the work was to determine the tolerance of the sulfidogenic sludge generated from hydrothermal vent sediments at microcosms level to different concentrations of Fe, Cu and Zn and the effect on the microbial community. In this study the chemical oxygen demand (COD) removal, sulfate-reducing activity (SRA) determination, inhibition effect through the determination of IC50, and the characterization of the bacterial community´s diversity were conducted. The IC50 on SRA was 34 and 81 mg/L for Zn and Cu, respectively. The highest sulfide concentration (H2S mg/L) and % of sulfate reduction obtained were: 511.30 ± 0.75 and 35.34 ± 0.51 for 50 mg/L of Fe, 482.48 ± 6.40 and 33.35 ± 0.44 for 10 mg/L of Cu, 442.26 ± 17.1 and 30.57 ± 1.18 for 10 mg/L of Zn, respectively. The COD removal rates were of 71.81 ± 7.6, 53.92 ± 1.07 and 57.68 ± 10.2 mg COD/ L d for Fe (50 mg/L), Cu (40 mg/L) and Zn (20 mg/L), respectively. Proteobacteria, Firmicutes, Chloroflexi and Actinobacteria were common phyla to four microcosms (stabilized sulfidogenic and added with Fe, Cu or Zn). The dsrA genes of Desulfotomaculum acetoxidans, Desulfotomaculum gibsoniae and Desulfovibrio desulfuricans were expressed in the microcosms supporting the SRA results. The consortia could be explored for ex-situ bioremediation purposes in the presence of the metals tested in this work.

Heptapeptide HP3 acts as a potent inhibitor of experimental imiquimod­induced murine psoriasis and impedes the trans­endothelial migration of mononuclear cells.

During the progression of psoriatic lesions, abundant cellular infiltration of myeloid cells, such as macrophages and activated dendritic cells, occurs in the skin and the infiltrating cells interact with naive lymphoid cells to generate a T helper (Th)1 and Th17 environment. Therapies to treat psoriasis include phototherapy, non­steroidal and steroidal drugs, as well as antibodies to block tumor necrosis factor­α, interleukin (IL)­17­A and IL­12/IL­23, which all focus on decreasing the proinflammatory hallmark of psoriasis. The present study obtained the heptapeptide HP3 derived from phage display technology that blocks mononuclear cell adhesion to endothelial cells and inhibits trans­endothelial migration in vitro. The activity of the heptapeptide in a murine model of psoriasis was also assessed, which indicated that early administration inhibited the development of psoriatic lesions. Therefore, the results suggested that HP3 may serve as a potential therapeutic target for psoriasis.

Role of IL-36 Cytokines in the Regulation of Angiogenesis Potential of Trophoblast Cells.

IL-36 cytokines (the agonists IL-36α, IL-36ß, IL-36γ, and the antagonist IL-36Ra) are expressed in the mouse uterus and associated with maternal immune response during pregnancy. Here, we characterize the expression of IL-36 members in human primary trophoblast cells (PTC) and trophoblastic cell lines (HTR-8/SVneo and JEG-3) and upon treatment with bacterial and viral components. Effects of recombinant IL-36 on the migration capacity of trophoblastic cells, their ability to interact with endothelial cells and the induction of angiogenic factors and miRNAs (angiomiRNAs) were examined. Constitutive protein expression of IL-36 (α, ß, and γ) and their receptor (IL-36R) was found in all cell types. In PTC, transcripts for all IL-36 subtypes were found, whereas in trophoblastic cell lines only for IL36G and IL36RN. A synthetic analog of double-stranded RNA (poly I:C) and lipopolysaccharide (LPS) induced the expression of IL-36 members in a cell-specific and time-dependent manner. In HTR-8/SVneo cells, IL-36 cytokines increased cell migration and their capacity to interact with endothelial cells. VEGFA and PGF mRNA and protein, as well as the angiomiRNAs miR-146a-3p and miR-141-5p were upregulated as IL-36 response in PTC and HTR-8/SVneo cells. In conclusion, IL-36 cytokines are modulated by microbial components and regulate trophoblast migration and interaction with endothelial cells. Therefore, a fundamental role of these cytokines in the placentation process and in response to infections may be expected.

Marine Sediment Recovered Salinispora sp. Inhibits the Growth of Emerging Bacterial Pathogens and other Multi-Drug-Resistant Bacteria.

Marine obligate actinobacteria produce a wide variety of secondary metabolites with biological activity, notably those with antibiotic activity urgently needed against multi-drug-resistant bacteria. Seventy-five marine actinobacteria were isolated from a marine sediment sample collected in Punta Arena de La Ventana, Baja California Sur, Mexico. The 16S rRNA gene identification, Multi Locus Sequence Analysis, and the marine salt requirement for growth assigned seventy-one isolates as members of the genus Salinispora, grouped apart but related to the main Salinispora arenicola species clade. The ability of salinisporae to inhibit bacterial growth of Staphylococcus epidermidis, Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacer baumannii, Pseudomonas aeruginosa, and Enterobacter spp. was evaluated by cross-streaking plate and supernatant inhibition tests. Ten supernatants inhibited the growth of eight strains of S. epidermidis from patients suffering from ocular infections, two out of the eight showed growth inhibition on ten S. epidermidis strains from prosthetic joint infections. Also, it inhibited the growth of the remaining six multi-drug-resistant bacteria tested. These results showed that some Salinispora strains could produce antibacterial compounds to combat bacteria of clinical importance and prove that studying different geographical sites uncovers untapped microorganisms with metabolic potential.

Overview of Staphylococcus epidermidis cell wall-anchored proteins: potential targets to inhibit biofilm formation.

Currently, the treatment of infections by Staphylococcus epidermidis (S. epidermidis) represents a challenge because some strains have multidrug-resistance to antimicrobial products (antibiotic and biocides) and can produce biofilms. These biofilms protect bacterial cells from both antimicrobials and the host immune response. Therefore, it is crucial to encourage research on the development of new treatments. One method is immunotherapy, targeting components of S. epidermidis, such as S. epidermidis surface (Ses) proteins. Ses is expressed constitutively in most strains, and they participate in biofilm formation. This review is an update on Ses, regarding their structure, biological function, their relationship with S. epidermidis biofilm formation, and its possible role as therapeutic targets to develop immunotherapeutic treatments to prevent infections by S. epidermidis.

Differential Expression of the apsXRS System by Antimicrobial Peptide LL-37 in Commensal and Clinical Staphylococcus epidermidis Isolates.

The three-component apsXRS system senses and responds to cationic antimicrobial peptides (CAMPs), which induces the expression of the dlt operon and the genes mprF and vrafG, modifying the surface net charge in Staphylococcus epidermidis, resulting in the repulsion of CAMPs. The apsXRS system has been only studied in the S. epidermidis 1457 strain, and there are no studies of prevalence and level of expression of apsXRS in commensal and clinical isolates. From 60 isolates, those selected from commensal healthy skin (n = 20), commensal healthy conjunctive (n = 10), and clinical ocular infection (n = 30) presented the apsX, apsR, and apsS genes in their genomes. Constitutive expression of apsX, apsR, and apsS genes was determined by RT-qPCR in all isolates. It was found that expression of apsX, apsR, and apsS was 3.3-5.9-fold higher in commensal isolates stimulated with LL-37 (15 µg/mL) than in clinical isolates. Similarly, expression of the dlt operon and the genes mprF, and vraFG was 8-10-fold higher in commensal isolates than in clinical. However, LL-37 did not increase the addition of lysine in the phospholipids of the cytoplasmic membrane in any of the isolates. Mutations in the apsS loop region, apsR, and their promoter sequence were not found. These results demonstrated that apsXRS system is essential in all isolates for its constitutive expression; however, LL-37 caused an increase of apsXRS expression in commensal isolates, suggesting that S. epidermidis isolates do not respond in the same way to the presence of LL-37.

Non-biofilm-forming commensal Staphylococcus epidermidis isolates produce biofilm in the presence of trypsin.

Epidemiological studies comparing clinical and commensal Staphylococcus epidermidis isolates suggest that biofilm formation is a discriminant biomarker. A study showed that four non-biofilm-forming clinical S. epidermidis isolates could form an induced biofilm by trypsin treatment, suggesting that S. epidermidis can form biofilms in a protease-independent way and in a trypsin-induced way. In this study, the trypsin capacity to induce biofilm formation was evaluated in non-biofilm-forming S. epidermidis isolates (n = 133) in order to support this mechanism and to establish the importance of total biofilms (meaning the sum of protease-independent biofilm and trypsin-induced biofilm). Staphylococcus epidermidis isolates from ocular infections (OI; n = 24), prosthetic joint infections (PJI; n = 64), and healthy skin (HS-1; n = 100) were screened for protease-independent biofilm formation according to Christensen's method. The result was that there are significant differences (p < .0001) between clinical (43.2%) and commensal (17%) protease-independent biofilm producers. Meanwhile, non-biofilm-forming isolates were treated with trypsin, and biofilm formation was evaluated by the same method. The number of commensal trypsin-induced biofilm producers significantly increased from 17% to 79%. In contrast, clinical isolates increased from 43.2% to 72.7%. The comparison between clinical and commensal total biofilm yielded no significant differences (p = .392). A similar result was found when different isolation sources were compared (OI vs. HS-1 and PJI vs. HS-1). The genotype icaA- /aap+ was associated with the trypsin-induced biofilm phenotype; however, no correlation was observed between aap mRNA expression and the level of trypsin-induced biofilm phenotype. Studying another group of commensal S. epidermidis non-biofilm-forming isolates (HS-2; n = 139) from different body sites, it was found that 70 isolates (60.3%) formed trypsin-induced biofilms. In conclusion, trypsin is capable of inducing biofilm production in non-biofilm-forming commensal S. epidermidis isolates with the icaA- /aap+ genotype, and there is no significant difference in total biofilms when comparing clinical and commensal isolates, suggesting that total biofilms are not a discriminant biomarker.

Prevalence and virulence factors of coagulase negative Staphylococcus causative of prosthetic joint infections in an orthopedic hospital of Mexico.

Objective: To determine the prevalence and virulence factors of coagulase-negative Staphylococci (CNS) in prosthetic joint infections (PJI). Method: CNS were isolated of 66 hip and knee PJI from Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra, México City. Antimicrobial susceptibility and biofilm formation in CNS were determined; icaADBC, aap, bap and embp genes were determined by PCR. Results: Staphylococcus and Staphylococcus hominis were the most prevalent with 82 y 80% respectively. Staphylococcus lugdunensis, Staphylococcus haemolyticus, Staphylococcus capitis, Staphylococcus caprae, Staphylococcus sciuri and Staphylococcus lentus were less frequent. The majority of isolates were resistant to ß-lactam antibiotics, fluoroquinolone, and erythromycin. 41% of CNS were biofilm former and 59% were non-biofilm former (p = 0.0551). Biofilm former Staphylococcus epidermidis showed a high presence of icaADBC, aap and embp operons compared to the non-biofilm former isolates (p < 0.05). In contrast, non-S. epidermidis CNS had only the aap gen. Conclusion: S. haemolyticus, S. sciuri and S. lentus are new isolates of PJI not previously reported with virulence factors similar to CNS isolates.

Objetivo: Estudiar la prevalencia y los factores de virulencia de Staphylococcus coagulasa negativos (SCN) de infecciones de prótesis articular (IPA). Método: Los SCN se aislaron de 66 pacientes con IPA de cadera y rodilla procedentes del Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra, de Ciudad de México. Se determinaron la sensibilidad antimicrobiana y la producción de biopelículas de los SCN. Los genes icaADBC, aap, bap y embp fueron detectados por reacción en cadena de la polimerasa en SCN. Resultados: La IPA de cadera fue el 80%. Se aislaron en alta proporción S. epidermidis (82%) y S. hominis (80%), y en baja frecuencia S. lugdunensis, S. haemolyticus, S. capitis, S. caprae, S. sciuri y S. lentus. La mayoría de los aislamientos fueron resistentes a los betalactámicos, las fluoroquinolonas y la eritromicina. La producción de biopelículas se determinó en el 41% de los SCN y el 59% fueron no productores de biopelículas (p = 0.0551). S. epidermidis productores de biopelículas tuvieron mayor presencia del operón icaADBC, aap y embp que los aislamientos no productores de biopelícula (p < 0.05). Los SCN no S. epidermidis presentaron únicamente el gen aap. Conclusiones: S. haemolyticus, S. sciuri y S. lentus son aislamientos nuevos de IPA no reportados que poseen factores de virulencia, igual que las otras especies de SCN aisladas.

sesA, sesB, sesC, sesD, sesE, sesG, sesH, and embp genes are genetic markers that differentiate commensal isolates of Staphylococcus epidermidis from isolates that cause prosthetic joint infection.

OBJECTIVES: Staphylococcus epidermidis can cause prosthetic joint infections. Strategies to differentiate between healthy skin and prosthetic joint infections isolates are relatively ineffective, which makes necessary to search for new differential biomarkers. Staphylococcus epidermidis has eleven surface proteins, denoted as Ses proteins. In this work, ses genes are used as biomarkers to differentiate between prosthetic joint infections and healthy skin isolates. METHODS: All prosthetic joint infections (n = 51) and healthy skin (n = 51) isolates were genotyped by pulsed-field gel electrophoresis. icaA, embp, sesA-I, and sdrF genes were determined by PCR. The phenotypic data included biofilm production and antibiotic resistance. RESULTS: 10 pulsed-field gel electrophoresis profiles were identified: four profiles were exclusive of prosthetic joint infections isolates, three profiles presented a higher proportion in prosthetic joint infections isolates and three profiles presented a higher proportion in healthy skin isolates. sesA, sesB, sesC, sesD, sesE, sesG, and sesH genes were more prevalent in healthy skin isolates than in prosthetic joint infections isolates (p < .05). Prosthetic joint infections isolates were more resistant to oxacillin (78%), ciprofloxacin (60%), levofloxacin (60%), and moxifloxacin (57%). The principal coordinate analysis and a discriminant analysis found that prosthetic joint infections isolates had as discriminant biomarker the biofilm formation, the icaA gene, oxacillin, ciprofloxacin, levofloxacin, moxifloxacin, and gentamicin resistance. In contrast, the healthy skin isolates had as discriminant biomarkers the embp, sesA, sesB, sesC, sesD, sesE, sesG, and sesH genes. CONCLUSIONS: These data suggest that ses genes can be considered biomarkers to differentiate between S. epidermidis commensal and prosthetic joint infections clinical.

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.

Extracellular proteases of Staphylococcus epidermidis: roles as virulence factors and their participation in biofilm.

Staphylococci produce a large number of extracellular proteases, some of which are considered as potential virulence factors. Staphylococcus epidermidis is a causative agent of nosocomial infections in medical devices by the formation of biofilms. It has been proposed that proteases contribute to the different stages of biofilm formation. S. epidermidis secretes a small number of extracellular proteases, such as serine protease Esp, cysteine protease EcpA, and metalloprotease SepA that have a relatively low substrate specificity. Recent findings indicate a significant contribution of extracellular proteases in biofilm formation through the proteolytic inactivation of adhesion molecules. The objective of this work is to provide an overview of the current knowledge of S. epidermidis' extracellular proteases during pathogenicity, especially in the different stages of biofilm formation.