Bacterial Microenvironment Research Articles

Copper ferrite heterojunction coatings empower polyetheretherketone implant with multi-modal bactericidal functions and boosted osteogenicity through synergistic photo/Fenton-therapy

Drug-free antibacterial therapy, such as photodynamic therapy and chemodynamic therapy, has become a mainstream in the treatment of implant-associated infection (IAI) due to its considerable potential on effective eradication of pathogenic bacteria via yielding overwhelming reactive oxygen species (ROS). However, superfluous ROS after therapeutical process may elicit a detrimental effect on subsequent tissue regeneration. To address this tough issue, we innovatively devise a photo-activated copper ferrite (CuFe2O4) heterojunction coating on bioinert polyetheretherketone (PEEK) implant through hydrothermal treatment and π-π-π stacking. The heterojunction coatings not only generate localized hyperthermia and ROS upon 808 nm NIR illumination, but also trigger Fenton(-like) reaction and glutathione (GSH) depletion in bacterial infectious microenvironment (IME), all leading to robust and cyclic antibacterial property through synergistic photothermal/photodynamic/chemodynamic therapy. Besides, the decorated implants are demonstrated to show superior cytocompatibility and osteogenic-promoting capability. The mice subcutaneous implantation further confirms the excellent in vivo photo-disinfection. The advantage of the heterojunction coatings lies on its enhancement in tissue generation and osteogenesis after antibacterial dynamic therapy because the liberation of micronutrient element (Cu, Fe) is significantly augmented exposed to NIR light, showing photo-enhanced osteogenicity. As envisaged, this work provides a new strategy to empower PEEK implants with an integrative feature of bacteriostasis and osteogenicity to combat intractable IAI through synergistic photo/Fenton-therapy.

PH-responsive spiropyran-based copolymers and their application in monitoring and antibacterial coatings

Although many multifunctional antibacterial materials have been developed, there are few antibacterial materials that can simultaneously monitor pathogenic bacteria and sterilize efficiently. In this work, pH-responsive spiropyran-based fluorinated copolymers with antibacterial, antifouling and fluorescence performances were prepared. First, the random copolymer of methacrylic acid and 1H,1H,2H,2H-perfluorododecyl acrylate (P(MAA-co-FDA)) were synthesized by RAFT polymerization. Second, spiropyran (SP) was grafted onto P(MAA-co-FDA) to obtain the P(MAA-co-SP-co-FDA) copolymer with fluorescence property. At the third step, the remaining carboxyl groups in the grafted copolymer were complexed with protonated polyhexamethylene biguanidine salt (PHMB) to obtain the P(MAA-co-SP-co-FDA)/PHMB copolymer complex antibacterial materials. The results show that the copolymer complex coatings can effectively inhibit the adhesion of bacteria and release PHMB in a bacterial microenvironment to kill S. aureus and E. coli but remain noncytotoxic. The P(MAA-co-SP-co-FDA) copolymer or its complex with PHMB can open the ring and generate a red fluorescence under acidic conditions produced by bacterial growth and metabolism. In addition, the coatings have good biocompatibility, which may be suitable for medical devices to reduce bacterial infection in vivo and in vitro. The prepared multifunctional materials with excellent anti-adhesion, antimicrobial and fluorescence characters will have a broad application prospect in antibacterial, antifouling and monitoring of medical devices.

An acid-triggered porphyrin-based block copolymer for enhanced photodynamic antibacterial efficacy

Bacterial infection, especially multidrug-resistant (MDR) bacterial infection has threatened public health drastically. Here, we fabricate an “acid-triggered” nanoplatform for enhanced photodynamic antibacterial activity by reducing the aggregation of photosensitizers (PSs) in bacterial acidic microenvironment. Specifically, a functional amphiphilic block copolymer was first synthesized by using a pH-sensitive monomer, 2-(diisopropylamino) ethyl methacrylate (DPA) and porphyrin-based methacrylate (TPPC6MA) with poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) as the macromolecular chain transfer agent, and POEGMA-b-[PDPA-co-PTPPC6MA] block copolymer was further self-assembled into spherical nanoparticles (PDPA-TPP). PDPA-TPP nanoparticles possess an effective electrostatic adherence to negatively charged bacterial cell membrane, since they could rapidly achieve positive charge in acidic bacterial media. Meanwhile, the acid-triggered dissociation of PDPA-TPP nanoparticles could reduce the aggregation caused quenching (ACQ) of the photosensitizers, leading to around 5 folds increase of the singlet oxygen (1O2) quantum yield. In vitro results demonstrated that the “acid-triggered” PDPA-TPP nanoparticles could kill most of MDR S. aureus (Gram-positive) and MDR E. coli (Gram-negative) by enhanced photodynamic therapy, and they could resist wound infection and accelerate wound healing effectively in vivo. Furthermore, PDPA-TPP nanoparticles could well disperse the biofilm and almost kill all the biofilm-containing bacteria. Thus, by making use of the bacterial acidic microenvironment, this “acid-triggered” nanoplatform in situ will open a new path to solve the aggregation of photosensitizers for combating broad-spectrum drug-resistant bacterial infection.

Bacterial infection microenvironment sensitive prodrug micelles with enhanced photodynamic activities for infection control

Because of the severe antibiotic resistance, photodynamic therapy is considered as a potent method for the treatment of bacterial infection with bare drug resistance. However, its therapeutic efficacy is not always satisfactory in practical treatment. In this study, pH-responsive prodrug micelles were prepared by conjugation of chlorin e6 to polyethylene glycol-b-poly(2-(hexamethyleneimino) ethyl methacrylate-co-aminoethyl methacrylate) for improving the antimicrobial activity of photodynamic therapy. The micelles were negatively charged in normal physiological environment, which was very important for long blood circulation. However, the micelles could turn to be positively charged in bacterial infection microenvironment and then adhere to negatively charged bacterial membranes, which could significantly improve their antibacterial activity against both methicillin-resistant Staphylococcus aureus and Escherichia coli after laser irradiation. The in vivo experiment showed excellent antibacterial effect of pH-sensitive micelles in a subcutaneous infection model. The micelles showed great potential in the photodynamic therapy of stubborn bacterial infections.

A ruthenium nanoframe/enzyme composite system as a self-activating cascade agent for the treatment of bacterial infections.

The cascade catalytic strategy could effectively enhance the antibacterial activity by regulating the production of hydroxyl radicals (˙OH) in the sites of bacterial infection. In this work, a ruthenium metal nanoframe (Ru NF) was successfully synthesized via the palladium template method. The cascade catalysis in the bacterial infection microenvironment was achieved by physically adsorbed natural glucose oxidase (GOx), and hyaluronic acid (HA) was coated on the outer layer of the system for locating the infection sites accurately. Eventually, a composite nano-catalyst (HA-Ru NFs/GOx) based on the ruthenium nanoframe was constructed, which exhibited excellent cascade catalytic activity and good biocompatibility. The prepared HA-Ru NFs/GOx enhances the antibacterial activity and inhibits bacterial regeneration through the outbreak of reactive oxygen species (ROS) caused by self-activating cascade reactions. In addition, in vivo experiments indicate that HA-Ru NFs/GOx could efficiently cause bacterial death and significantly promote wound healing/skin regeneration. Accordingly, ruthenium metal framework nanozymes could be used as an effective cascade catalytic platform to inhibit bacterial regeneration and promote wound healing, and have great potential as new antibacterial agents against antibiotic-resistant bacteria.

A novel biodegradable Mg-1Zn-0.5Sn alloy: Mechanical properties, corrosion behavior, biocompatibility, and antibacterial activity

To meet the growing demand for antibacterial implants for bone-implant-associated infection therapy and avoid the adverse effects of secondary surgery, a degradable platform with pH responsiveness and ion-associated antibacterial properties was constructed. A small amount of Sn added to Mg-1Zn alloy reduces the biocorrosion rate, which can be attributed to Sn participation in outer-layer film formation, significantly reducing the biocorrosion rate and hydrogen evolution rate after implantation in vivo . These Mg alloys, which are susceptible to degradation in the acidic bacterial microenvironment, degrade by releasing Mg, Zn and Sn, producing favorably alkaline and antibacterial conditions. Samples with the composition of Mg-1Zn-0.5Sn were found to be beneficial for promoting initial cell adhesion and proliferation, resulting in improved biocompatibility and biosafety. The biocompatibility of this alloy was confirmed by the healthy behavior of animals and the absence of acute or chronic toxicity in the liver, spleen, and kidneys. Our results demonstrate that Mg-1Zn-0.5Sn is safe for biological systems, enabling its efficacious use in biomedical applications.

PH Switchable Nanoplatform for In Vivo Persistent Luminescence Imaging and Precise Photothermal Therapy of Bacterial Infection

AbstractPhotothermal therapy (PTT) is one of the most promising approaches to combat multidrug‐resistant bacteria with less potential to induce resistance and systemic toxicity. However, uncontrollable distribution of photothermal agents leads to lethal temperatures for normal cells, and failure to offer timely and effective antibacterial stewardship. A pH switchable nanoplatform for persistent luminescence imaging‐guided precise PTT to selectively destroy only pathological cells while protecting nearby normal cells in bacterial infected microenvironment is shown. The PLNP@PANI‐GCS is fabricated by grafting polyaniline (PANI) and glycol chitosan (GCS) onto the surface of persistent luminescence nanoparticles (PLNPs). It takes advantage of the long persistent luminescence of PLNPs to realize autofluorescence‐free imaging, the pH‐dependent light–heat conversion property of PANI to get a stronger photothermal effect at pH 6.5 than pH 7.4, and the pH environment responsive surface charge transition of GCS. Consequently, PLNP@PANI‐GCS enables effective response to bacterial‐infected acid region and electrostatic bonding to bacteria in vivo, ensuring the spatial accuracy of near‐infrared light irradiation and specific heating directly to bacteria. In vivo imaging‐guided PTT to bacterial infection abscess shows effective treatment. PLNP@PANI‐GCS has great potential in treating multidrug‐resistant bacterial infection with low possibility of developing microbial drug resistance and little harm to normal cells.

The Role of H1 and H2 Blocker in Eradication of Gastrointestinal Malfunctioning

Proton pumps releases acids in GIT which results in increased level of alkaline phosphates. The liver irritation by increased alkaline phosphates results in histamine disbalance. H1 ANDH2 BLOCKER acts as histamine controlling agents. The bacteria use their flagella to stick in stomach mucosal layer. For bacterial growth optimal conditions includes oxygen level b/w 5-15%, approx. CO2 5%, availability of some special amino acids, and 30-37°C temperature. Gastro intestinal Infections involve a spiral-shaped, gram-negative, micro bacterium. It was assumed that earlier no germ might survive in gastric acidic layer, therefore the possibility of microbial colonization of stomach actually was not considered. Thus, the bacterial microenvironment directly surrounds and neutralize the effects of gastric secretions which are corrosive to them and the pathogen escapes.

Fabrication of magnesium/zinc-metal organic framework on titanium implants to inhibit bacterial infection and promote bone regeneration

The residual bacteria in the second revision surgery caused by infection would further lead to the failure of the implantation. Pathogenic bacteria adhesion to an implant surface not only interfere the functions of bone-formation related cells, but also activate the host immune system, thus resulting in inflammation and osteogenesis inhibition. Thus, to fabricate multifunctional (antibacterial, anti-inflammation and pro-osteogenesis) titanium implants is essential to address this issue. In this work, hybrid magnesium/zinc-metal organic framework (Mg/Zn-MOF74) coating was constructed on alkali-heat treated titanium (AT) surface. The hybrid Mg/Zn-MOF74 coating displayed good stability and its stability was related to the content of Zn2+. The MOF74-modified samples were sensitive to bacterial acid microenvironment and displayed strong antibacterial ability against both Escherichia coli and Staphylococcus aureus due to the degradation of MOF74 coating, leading to alkaline microenvironment (about pH 8.0) and degradation products (2,5-dihydroxyterephthalic acid and Zn2+). The coating also showed good early anti-inflammatory property to native Ti substrates. In vivo results further verified that AT-Mg/Zn3 implants had high antibacterial and anti-inflammatory properties at early stage of implantation, and greatly improved new bone formation around implants both at non-infected and infected femur sites.

Antibacterial Coatings: Responsive and Synergistic Antibacterial Coatings: Fighting against Bacteria in a Smart and Effective Way (Adv. Healthcare Mater. 3/2019)

In article number 1801381, Qian Yu and co-workers summarize the recent development of three types of responsive and synergistic antibacterial coatings, including self-defensive antibacterial coatings that are responsive to the bacterial microenvironment, synergetic antibacterial coatings that possess two or more killing mechanisms which interact synergistically, and smart “kill-and-release” antibacterial coatings that have triggered-cleaning capability.

Responsive and Synergistic Antibacterial Coatings: Fighting against Bacteria in a Smart and Effective Way.

Antibacterial coatings that eliminate initial bacterial attachment and prevent subsequent biofilm formation are essential in a number of applications, especially implanted medical devices. Although various approaches, including bacteria-repelling and bacteria-killing mechanisms, have been developed, none of them have been entirely successful due to their inherent drawbacks. In recent years, antibacterial coatings that are responsive to the bacterial microenvironment, that possess two or more killing mechanisms, or that have triggered-cleaning capability have emerged as promising solutions for bacterial infection and contamination problems. This review focuses on recent progress on three types of such responsive and synergistic antibacterial coatings, including i) self-defensive antibacterial coatings, which can "turn on" biocidal activity in response to a bacteria-containing microenvironment; ii) synergistic antibacterial coatings, which possess two or more killing mechanisms that interact synergistically to reinforce each other; and iii) smart "kill-and-release" antibacterial coatings, which can switch functionality between bacteria killing and bacteria releasing under a proper stimulus. The design principles and potential applications of these coatings are discussed and a brief perspective on remaining challenges and future research directions is presented.

Ratiometric fluorescent probes for selective and sensitive visualization of bacterial microenvironment protease activity.

The extracellular SspA protease of the human pathogen S. aureus is essential for evading the host immune defence system. Two novel FRET probes for selective real-time ratiometric imaging of SspA activity in live S. aureus cells are reported.

Microenvironment-Responsive Magnetic Nanocomposites Based on Silver Nanoparticles/Gentamicin for Enhanced Biofilm Disruption by Magnetic Field.

Biofilms contribute to persistent bacterial infections as well as formidable resistances to conventional antibiotics. However, it is still a major challenge to establish an advanced antibacterial nanoplatform that can efficiently eradicate biofilms while overcoming bacterial resistances. Taking advantage of the stimuli-responsive technique and the magnetic guidance strategy, here we present a highly efficient nanoplatform for planktonic inactivation and biofilm disruption. The multilayer films consisting of antibiotic gentamicin (Gen), tannic acid, and silver nanoparticles (AgNPs) were fabricated and coated on magnetic nanoparticles via electrostatic interactions. To achieve controlled drug release and improved biocompatibility, biodegradable hyaluronic acid was capped on the outer surface as a responsive shell. In vitro release profiles suggested that the nanocomposites showed both enzyme and pH-responsive release properties. The nanoplatform could be employed as a powerful nanocarrier for small molecular Gen and AgNPs delivery and on-demand release in response to bacterial infection microenvironment. The nanocomposites also showed satisfying antibacterial capacities against planktonic Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Intriguingly, with magnetic field navigation (NdFeB, 2000 gauss), the nanocomposites could be guided to handily penetrate into S. aureus biofilm and performed dual-responsive release, showing significantly enhanced biofilm disruption. Moreover, excess reactive oxygen species production resulting from the nanocomposites contributed to the decomposition of biofilm matrix and ultimate biofilm eradication. As a consequence, the ingenious antibacterial nanoplatform could be promising for combating biofilm infections while overcoming bacterial resistances with extra environmental factors such as magnetic field.

Construction of High Drug Loading and Enzymatic Degradable Multilayer Films for Self-Defense Drug Release and Long-Term Biofilm Inhibition.

Bacterial infections and biofilm formation on the surface of implants are important issues that greatly affect biomedical applications and even cause device failure. Construction of high drug loading systems on the surface and control of drug release on-demand is an efficient way to lower the development of resistant bacteria and biofilm formation. In the present study, (montmorillonite/hyaluronic acid-gentamicin)10 ((MMT/HA-GS)10) organic/inorganic hybrid multilayer films were alternately self-assembled on substrates. The loading dosage of GS was as high as 0.85 mg/cm2, which could be due the high specific surface area of MMT. The obtained multilayer film with high roughness gradually degraded in hyaluronidase (HAS) solutions or a bacterial infection microenvironment, which caused the responsive release of GS. The release of GS showed dual enzyme and bacterial infection responsiveness, which also indicated good drug retention and on-demand self-defense release properties of the multilayer films. Moreover, the GS release responsiveness to E. coli showed higher sensitivity than that to S. aureus. There was only ∼5 wt % GS release from the film in PBS after 48 h of immersion, and the amount quickly increased to 30 wt % in 105 CFU/mL of E. coli. Importantly, the high drug dosage, smart drug release, and film peeling from the surface contributed to the efficient antibacterial properties and long-term biofilm inhibition functions. Both in vitro and in vivo antibacterial tests indicated efficient sterilization function and good mammalian cell and tissue compatibility.

Advance in Bacteria Chemotaxis on Microfluidic Devices

Abstract Chemotaxis is the response ability of motile cells to chemicals gradients in environment and the migration toward higher concentration of chemoattractant or lower concentration of repellent. This mechanism is a basic nature of microorganisms to adapt to the environmental changes. The research of microbial chemotaxis is of great significance in utilizing bacteria to solve environment problems, control the pathogen infection, and develop microbial industrial projects. Microfluidic devices can realize qualitative and quantitative detection of bacterial chemotaxis. In comparison with traditional detection methods, microfluidic assay has an accurate control over bacterial microenvironment with higher sensitivity. In the past few years, the study on bacterial chemotaxis based on microfluidic assay was developed rapidly. In this paper, the microfluidic chemotaxis detectors that appeared in recent years were introduced from the aspects of chip structure, working principle and their applications. Finally, we provided insights into the challenges of bacterial chemotaxis and provided future perspectives.

Bacterial infection microenvironment-responsive enzymatically degradable multilayer films for multifunctional antibacterial properties.

The adhesion of bacteria is one of the most important stages in biofilm formation and bacterial infection. Once bacteria have adhered to a biomaterial surface, it is hard to eliminate them, and bacterial growth and infection are inevitable. In the current study, we have designed and constructed enzymatically degradable (hyaluronic acid/chitosan)n-(hyaluronic acid/polylysine)n ((HA/CHI)n-(HA/PLL)n) composite multilayer films via a layer-by-layer self-assembly method. Spectroscopic ellipsometry and scanning electron microscopy cross section measurements showed the exponential growth behavior of (HA/CHI)10-(HA/PLL)10 multilayer films (∼2 μm). The increased secretion of hyaluronidase and chymotrypsin in the bacterial infection microenvironment led to the fast degradation of the outer (PLL/HA)n multilayer films in the first 24 h. Enzymatic degradation of the multilayer films efficiently reduced the adhesion of both Staphylococcus aureus and Escherichia coli (>99%). Bacterial live/dead staining demonstrated the bactericidal action of the remaining bottom (CHI/HA)n multilayer films against the two kinds of bacteria. In vivo subcutaneous tests on New Zealand white rabbits, wound appearance and histopathology analysis showed that the implantation of composite multilayer film-modified PDMS promoted wound healing and the materials demonstrated a self-defense antibacterial effect. The material demonstrated both anti-adhesive and bactericidal properties and could be used to modify biomedical implants.

Clay-to-Carbon Ratio Controls the Effect of Herbicide Application on Soil Bacterial Richness and Diversity in a Loamy Field

Soil texture and soil organic carbon (OC) influence the bacterial microenvironment and also control herbicide sorption. A field-scale exploratory study was conducted to investigate the potential interaction between soil texture parameters, herbicides, and soil bacterial richness and diversity. Glyphosate and bentazon were used to evaluate the herbicidal effect on bacterial community under different conditions created by clay and OC gradients in a loamy field. Metabarcoding by high-throughput sequencing of bacterial rDNA was used to estimate bacterial richness and diversity using OTUs, abundance-based coverage (ACE), Shannon diversity index, and phylogenetic diversity. In general, bacterial richness and diversity increased after bentazon application and decreased after glyphosate application. There was no significant effect for field locations with Dexter n (the ratio between clay and OC) values below 4.04 (the median of the values in the field study). The correlation coefficient (r) between bacterial richness and clay decreased after bentazon application, but increased after glyphosate application. Correlations between Dexter n and bacterial indices followed the same pattern, decreasing after bentazon application and increasing after glyphosate application. This indicated that the specific chemical nature of individual herbicides affected bacterial communities. This study reinforced the importance of including soil physical and chemical characteristics to explain the influence of pesticides on the variation in soil bacterial communities in agroecosystems.

Intraepithelial lymphocytosis is a frequent finding in biopsies from ileal pouch–anal anastomoses

Following restorative proctocolectomy with an ileal pouch-anal anastomosis, the small bowel mucosa undergoes several specific histologic adaptions, which may be unrelated to the underlying disease or symptoms of pouchitis. An increase in intraepithelial lymphocytes (IELs) has not been described as part of this spectrum. Mucosal biopsies of the ileal pouch and afferent limb of 230 patients (mean age: 45.7y [18.3-74.7], gender [female/male]: 117/113) with a functioning ileal pouch-anal anastomosis (mean time since ileostomy closure: 10.8months) and associated clinically annotated outcome data were assessed for IELs/100 enterocytes. Forty-two patients (18.3%) showed an increase in IELs (≥20 IELs/100 enterocytes [range 20-39]), in pouch and/or afferent limb biopsies. Intraepithelial lymphocytosis was more commonly observed in afferent limb compared to pouch biopsies (18.8% vs 8.3%; P = .42) and in familial adenomatous polyposis compared to ulcerative colitis patients (16% vs 8%; P = 0.36), but neither difference reached statistical significance. No cases with increased IELs displayed severe villous blunting. Increased IELs were not significantly associated with age, sex, ethnicity, smoking history, time since ileostomy, use of antibiotics, biologic agents, anti-diarrheal agents or probiotics, C-reactive protein levels or differential white cell count. None of the 42 patients with increased IELs had positive celiac serology (anti-human tissue transglutaminase IgA [ELISA] with corresponding total serum IgA). Intraepithelial lymphocytosis in pouch biopsies may represent a subclinical response to an altered bacterial microenvironment. Pathologists should be aware that intraepithelial lymphocytosis is part of the spectrum of changes in pouch biopsies, and only rarely is due to celiac disease.

Effect of Safflower Oil on Concentration of Conjugated Linoleic Acid of Kefir Prepared by Low-fat Milk.

Conjugated linoleic acid (CLA) is a special fatty acid in dairy products with unique antioxidant and anti-cancerous effects. Kefir, a milk product, comprises normalized homogenized cow's milk, the fructose and lactulose syrup as well as a symbiotic starter which has improved probiotic characteristics. The study was aimed to discuss patents and to examine the effect of different safflower oil concentrations on CLA content of the kefir drink prepared by low-fat milk. Safflower oil was added at 0.1, 0.3 and 0.5% (V/V) to low-fat cow's milk and six formulations of kefir samples were prepared. The CLA content of the kefir products was measured at pH=6.0 and pH=6.8 by gas chromatography. Acid and bile tolerance of bacterial microenvironment in the products were also determined. Substitution of natural fat content of milk with safflower oil resulted in proportional increase in the CLA contents of kefir in a dose dependent manner. The highest concentration of CLA was found under 0.5% (V/V) of safflower oil at pH 6.0 and temperature of 37 °C. Adding the Safflower oil into milk used for kefir production, increased CLA content from 0.123 (g/100 g) in pure safflower free samples to 0.322 (g/100 g) in samples with 0.5% (V/V) of safflower oil. The current study revealed that substitution of safflower oil with natural fat of cow's milk may help the production of kefir samples with remarkable increase in CLA content of final product.

La modulación de la expresión de IL-10 por el polimorfismo IL-10-592C/A (rs1800872) es independiente de la presencia y carga bacteriana de los periodontopatógenos clásicos

ObjectiveA study was conducted to investigate the possible influence of the single nucleotide polymorphism (SNP) IL-10-592C/A on the occurrence and load of the periodontal pathogens: P. gingivalis, T. forsythia, T. denticola and A. Actinomycetemcomitans; as well to investigate the influence of microbial and genetic factors on the modulation of local IL-10 mRNA levels. MethodologyThe study included 117 cases and 58 controls. After clinical examination microbiological samples were obtained and the detection/quantification of the target bacterial species was performed by RT-PCR. SNP rs1800872 was assayed by restriction fragment length polymorphism (RFLP). ResultsAllele distribution of rs1800872 was in Hardy-Weinberg equilibrium (P=64). As previously reported, polymorphic subjects demonstrated decreased IL-10 expression and increased risk of suffering chronic periodontitis. IL-10-592C/A rs1800872 SNP was not associated with the detection or the bacterial load of the investigated pathogens. Moreover, the presence/load of bacteria at periodontal sites did not influence IL-10 expression, which was determined by the genetic background of the study subjects. IL-10-592C/A SNP was not associated with detection/bacterial load of pathogenic bacteria. IL-10 expression levels were determined by the genetic background and were independent of the bacterial microenvironment.