Antimicrobial susceptibility and pathogenic genes of Staphylococcus aureus isolated from the oral cavity of patients with periodontitis

Molecular Dynamics Simulation Studies of Beta-Glucogallin and Dihydro Dehydro Coniferyl Alcohol from Syzygium cumini for its Antimicrobial Activity on Staphylococcus aureus

With the escalating threat of antimicrobial resistance (AMR), discovering novel therapeutic agents against resistant pathogens like Staphylococcus aureus is crucial. This study explores phytochemicals from Syzygium cumini for their potential efficacy against AMR S. aureus infections, elucidating their mechanisms through in silico methods. We investigated 83 compounds from S. cumini, sourced from PubMed, using rigorous docking analysis against the ATP binding domain AgrC of S. aureus with AMdock with Autodock Vina v1.5.2. Drug-likeness predictions were assessed using SwissADME v2023 and Pass online v2.0. Molecular dynamics (MD) simulations identified promising compounds, focusing on stability and interaction dynamics. Beta-Glucogallin (BEG) and Dihydro Dehydro Coniferyl alcohol (DIH) emerged as significant hits. MD simulations with GROMACS v2020.6 revealed stable BEG and DIH complexes with AgrC, forming six hydrogen bonds with six key amino acids (Arg-303, Asp-338, Glu-342, Glu-384, Lys-389, Gly-396), indicating strong and stable bonding. The binding affinities for DIH and BEG are -73.474 ± 11.104 kJ/mol and -6.319 ± 18.823 kJ/mol with 4BXI, respectively. Our findings highlight BEG and DIH as promising candidates against AMR S. aureus infections, showing favourable binding affinities and stable interactions with AgrC. This study underscores the importance of natural products in combating AMR and demonstrates the utility of computational methodologies in drug discovery. Further experimental validation is warranted to fully exploit these phytochemicals' therapeutic potential.

Study on the Prevalence of Methicillin-Resistant Staphylococcus Aureus Infection, Antibiotic Resistance Pattern, Biofilms Genes, and Antibiotic Resistance Genes from Clinical Samples

The global health situation is caused by Methicillin-Resistant Staphylococcus aureus (MRSA) strains, which exhibit resistance to the majority of antibiotics. The emergence and spread of antibiotic resistance make the treatment of these infections more complicated and intricate. The objective of this study was to investigate the mecA, blaZ, cna, and fnbA genes and the pattern of antibiotic resistance in S. aureus isolates obtained from different clinical samples. In this study, 78 strains of S. aureus were collected from different a variety of clinical specimens. The antibiotic susceptibility of the isolates was determined via the disk agar diffusion method. The prevalence of the mecA, blaZ, cna, and fnbA genes and the antimicrobial resistance patterns exhibited by the isolates against 10 conventional antibiotic disks were evaluated in these isolates. The data were analyzed using the SPSS statistical software version 25. Of the 78 samples collected, 63 samples were found to contain the mecA gene representing a prevalence of (62.2%). A total 63 S. aureus isolates were examined, of which is present in 60 (95.2%) exhibited the blaZ gene and 51 (81%) exhibited the fnbA gene. The frequency of the cna gene was observed in 42 (66.7%) samples. Additionally, a significant correlation was identified between the cna and fnbA genes and gentamicin and tetracycline antibiotic resistance with (P<0.05). The antibiotic resistance pattern revealed that all the isolates exhibited resistance to oxacillin (100%), penicillin (95.2%), and demonstrated the least resistance to vancomycin (3.2%), and Trimethoprim-sulfamethoxazole (17.5%). In comparison to other studies conducted in Iran, our findings indicate an average prevalence of MRSA. However, the level of resistance to commonly used antibiotics in these isolates was considerable. In this situation, it is recommended to monitor antibiotic resistance in these hospitals and medical centers.

Phytochemical Composition and Antimicrobial and Antibiofilm Effect of Myrciaria cauliflora Hydroethanolic Extract against Staphylococcus aureus and Acinetobacter baumannii

Staphylococcus aureus and Acinetobacter baumannii are opportunistic pathogens, and both are involved in different oral infections. This work aimed to analyze the phytochemical composition of Myrciaria cauliflora hydroethanolic extract and to evaluate its antimicrobial and antibiofilm action against Staphylococcus aureus (ATCC 6538) and Acinetobacter baumannii (ATCC 19606; multi-resistant clinical strains 58004, 50098, 566006, and H557). Myrciaria cauliflora hydroethanolic extract was prepared, and the content of soluble solids, flavonoids, and phenols was quantified. High-performance liquid chromatography (HPLC) was performed later. The minimum inhibitory concentration was determined using the broth microdilution method according to the Clinical and Laboratory Standards Institute, standard M7-A6, and subsequently, its minimum bactericidal concentration was determined. Then, the most effective concentrations were analyzed against biofilms. Statistical analysis was performed using the ANOVA method with Tukey's test. The soluble solids content in the prepared hydroethanolic extract of M. cauliflora was 2.22%. Additionally, the total flavonoid content, measured using the quercetin standard curve, was 0.040 mg/mL. Furthermore, the total phenol content, determined using the gallic acid standard curve, was 0.729 mg/mL. HPLC analysis presented peaks of gallic acid (11.80 m), p-coumaric acid (12.09 m), cinnamic acid derivative (19.02 m), and ellagic acid (29.83 m). The extract demonstrated antimicrobial and antibiofilm action against all tested strains. However, the most effective antibacterial concentration against all the tested bacteria was 5.55 mg/mL. Therefore, these chemical components justify that M. cauliflora hydroethanolic extract is effective in reducing biofilm formation in S. aureus (standard strain) and A. baumannii (standard and clinical strains).

The Oral Cavity-Another Reservoir of Antimicrobial-Resistant Staphylococcus aureus?

Staphylococcus aureus is one of the most common potentially pathogenic bacteria that may asymptomatically colonize many sites of healthy carriers. Non-nasal carriage, especially in the oral cavity, and its role in transmitting antimicrobial-resistant S. aureus strains in the healthcare community, is poorly understood. This study aimed to assess the prevalence and antimicrobial susceptibility of S. aureus in both oral and nasal cavities among preclinical dentistry students. A total of 264 oral and nasal swabs were taken from 132 participants, and all specimens were cultured using standard diagnostic procedures and antimicrobial susceptibility testing (EUCAST). The prevalence of S. aureus exclusively in the nasal (11.4%) or oral (9.1%) cavity was comparable, while concurrent oral and nasal carriage was present in 27.3% of participants. Although antibiotic resistance rates observed in both oral and nasal isolates were similar (ranging from 2.7% to 95.5%), 16.7% of carriers exhibited distinct antibiotic resistance profiles between oral and nasal isolates. Three (2.7%) methicillin-resistant S. aureus (MRSA) were isolated from the mouth and nose but multidrug resistance (27.3%) was more frequent in the oral than in the nasal isolates: 34% and 21.1%, respectively. This study demonstrated that preclinical dentistry students have a similar rate of oral S. aureus carriage as the nasal carriage rate, and that the oral cavity can be colonized by antimicrobial-resistant strains that do not originate from the nose. Consequently, the oral cavity seems to be an unjustly overlooked body site in screening for S. aureus carriage.

Periodontal disease in down syndrome: Predisposing factors and potential non-surgical therapeutic approaches

BACKGROUND

Periodontal diseases (PDs) have been documented to be significantly more prevalent and severe in patients with Down syndrome (DS). Different immunological and microbiological factors contributed to predisposing these patients to progressive and recurrent PDs.

AIM

The aim of this review was to investigate the altered immunological responses and oral microbiota disorders as well as focus on adjunctive non-surgical methods for the treatment of PDs and its applicability in patients with DS.

MATERIAL AND METHODS

A literature review was conducted addressing the following topics: (1) the altered immunological responses, (2) orofacial disorders related to DS patients, (3) oral microbiota changing, and (4) adjunctive non-surgical treatment and its efficacy in patients with DS.

RESULTS

Due to the early onset of PDs in children with DS, the need for prompt and effective treatment in these patients is essential.

DISCUSSION AND CONCLUSION

So, investigating underlying factors may open a new window to better understand the pathology of PDs in DS people and thus, find better strategies for treatment in such group. Although non-surgical treatments such as photodynamic therapy and probiotic consumption represented acceptable outcomes in different examined patients without DS, data about the application of these convenience and no need for local anesthesia methods in patients with DS is limited.

Antimicrobial resistance and virulence of subgingival staphylococci isolated from periodontal health and diseases

The dysbiotic biofilm of periodontitis may function as a reservoir for opportunistic human pathogens of clinical relevance. This study explored the virulence and antimicrobial susceptibility of staphylococci isolated from the subgingival biofilm of individuals with different periodontal conditions. Subgingival biofilm was obtained from 142 individuals with periodontal health, 101 with gingivitis and 302 with periodontitis, and cultivated on selective media. Isolated strains were identified by mass spectrometry. Antimicrobial susceptibility was determined by disk diffusion. The mecA and virulence genes were surveyed by PCR. Differences among groups regarding species, virulence and antimicrobial resistance were examined by Chi-square, Kruskal-Wallis or Mann-Whitney tests. The overall prevalence of subgingival staphylococci was 46%, especially in severe periodontitis (> 60%; p < 0.01). S. epidermidis (59%) and S. aureus (22%) were the predominant species across groups. S. condimenti, S. hominis, S. simulans and S. xylosus were identified only in periodontitis. High rates of resistance/reduced sensitivity were found for penicillin (60%), amoxicillin (55%) and azithromycin (37%), but multidrug resistance was observed in 12% of the isolates. Over 70% of the mecA + strains in periodontitis were isolated from severe disease. Higher detection rates of fnB + isolates were observed in periodontitis compared to health and gingivitis, whereas luxF/luxS-pvl + strains were associated with sites with deep pockets and attachment loss (p < 0.05). Penicillin-resistant staphylococci is highly prevalent in the subgingival biofilm regardless of the periodontal status. Strains carrying virulence genes related to tissue adhesion/invasion, inflammation and cytotoxicity support the pathogenic potential of these opportunists in the periodontal microenvironment.

Cytotoxicity Test of Active Compounds Natural Ingredients of Snail Mucus (Achatina fulica) Against BHK-21 Fibroblast Cells

Snails are unpleasant yet beneficial. Rural people have used one to treat illnesses like toothache for years. We will test snail's mucus Achatina fulica's cytotoxic activity against Baby Hamster Kidney (BHK-21) fibroblast cells at 12.5%, 25%, 50%, 100% and its resistance to Phorpyromonas gingivalis, Fusobacterium nucleatum, E. Faecalis, and S. aureus using Microtetrazolium (MTT) assay. The test and comparison solution was incubated with 5x103/100 l cells in 96-well plates. 5 mg/mL MTT completed the solution's incubation. ELISA readers measured purple color intensity. The formula transformed absorbance data at 595 nm into percent alive cells. ELISA readers read data. ANOVA, parametric Kolmogorov-Smirnov data normality test were performed. The cytotoxicity statistical test shows the following results: 12.5 % (0.76875 ±0.01117), 25% (0.49350 ±0.004796), 50% (0.30250 ±0.006658) and 100% (0.171 ±0.10488). The lowest cytotoxicity of Achatina fulica snail mucus is 12.5% with an average of 0.768. Achatina fulica snail mucus resists Phorpyromonas gingivalis, Fusobacterium nucleatum, E. Faecalis, and S. aureus at 12.5%.

Genetic Characterization of Staphylococcus aureus, Staphylococcus argenteus, and Coagulase-Negative Staphylococci Colonizing Oral Cavity and Hand of Healthy Adults in Northern Japan

The spread of methicillin resistance and virulence among staphylococci in the community poses a public health concern. In this study, we investigated the prevalence of Staphylococcus species colonizing the oral cavity and hand (skin) of healthy university students and their phenotypic and genetic characteristics in northern Japan. Among a total of 332 subjects, 6 and 110 methicillin-resistant and susceptible Staphylococcus aureus (MRSA and MSSA, respectively) isolates were recovered from 105 subjects. MRSA isolates were genotyped as CC5, CC8, CC45, and CC59 with SCCmec-IIa or IV, among which an isolate of ST6562 (single-locus variant of ST8) harbored SCCmec-IVa, PVL genes and ACME-I, which are the same traits as the USA300 clone. ST1223 S. argenteus was isolated from the oral cavity and hand of a single student. Coagulase-negative Staphylococcus (CoNS) was recovered from 154 subjects (172 isolates), and classified into 17 species, with S. capitis being the most common (38%), followed by S. warneri (24%) and S. epidermidis (15%), including nine mecA-positive isolates. S. capitis was differentiated into seven clusters/subclusters, and genetic factors associated with the NRCS-A clone (nsr, tarJ, ebh) were detected in 10–21% of isolates. The colonization of the USA300-like MRSA variant and S. capitis with the traits of the NRCS-A clone in healthy individuals was noteworthy.

Is the Oral Cavity of Intensive Care Unit Pediatric Patients More Susceptible to Methicillin-Resistant Staphylococcus aureus Infection?

Objective: The aim of this study was to assess the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the oral cavity of pediatric patients hospitalized at an intensive care unit (ICU). Methodology: Thirty ICU patients (group 1) and 30 healthy patients (group 2), between 1 and 12 years of age, matched by sex and age, were selected from a public hospital in Brazil. After oral examinations, biological specimens (nostril swab, oral mucosa, and supragingival biofilm) were collected from both groups to verify the presence of Staphylococcus aureus. Identification occurred after growth in Tryptic Soy Broth with 7.5% of NaCl for 48 hours, growth in Mannitol Salt Agar, gram staining, catalase, and coagulase tests. S. aureus isolates were submitted to antibiotic sensitivity test. Results: Only 36.7% of patients in the ICU perform oral hygiene during the hospitalization period and 41.7% presented high level of dental biofilm accumulation. The presence of S. aureus was similar in patients from group 1 (43.3%, 13) and group 2 (50.0%, 15) (p = 0.60). Both groups presented 18 samples each that tested positive for S. aureus. However, when considering patients infected by MRSA, the prevalence was higher in group 1 (eight; 26.7%) than in group 2 (five; 16.7%) but no statistical difference was observed (p = 0.53). In group 1, nine MRSA samples were resistant to erythromycin and seven to clindamycin. In group 2, two MRSA samples were resistant to erythromycin and two to clindamycin. Conclusions: Although ICU children did not show a significant higher carriage of MRSA when compared with the healthy group in the population studied, the number of highly resistant strains in the oral cavity isolated from ICU patients adds an important risk factor to be considered by the medical team as possible source of systemic infections, extended hospital stay, and poor outcomes.

A Molecular View on Biomaterials and Dental Stem Cells Interactions: Literature Review

Biomaterials and stem cells are essential components in the field of regenerative medicine. Various biomaterials have been designed that have appropriate biochemical and biophysical characteristics to mimic the microenvironment of an extracellular matrix. Dental stem cells (DT-MSCs) represent a novel source for the development of autologous therapies due to their easy availability. Although research on biomaterials and DT-MSCs has progressed, there are still challenges in the characteristics of biomaterials and the molecular mechanisms involved in regulating the behavior of DT-MSCs. In this review, the characteristics of biomaterials are summarized, and their classification according to their source, bioactivity, and different biological effects on the expansion and differentiation of DT-MSCs is summarized. Finally, advances in research on the interaction of biomaterials and the molecular components involved (mechanosensors and mechanotransduction) in DT-MSCs during their proliferation and differentiation are analyzed. Understanding the molecular dynamics of DT-MSCs and biomaterials can contribute to research in regenerative medicine and the development of autologous stem cell therapies.

Dual functional carbonate-hydroxyapatite nanocomposite from Pinctada maxima and egg-white for bone tissue engineering

This study aims to design a 3D carbonate-hydroxyapatite (CHA)/sago (S) based egg white (EW) microstructure with antibacterial properties to improve the performance of bone grafts for bone tissue engineering. In this study, Pinctada maxima (P. maxima) shell was used as a calcium (Ca) source in CHA synthesis. The annealing temperature of CHA at 900, 1000, and 1100 °C affected microstructural and lattice parameters, with stoichiometry 1.72-1.77, and B-type CHA was identified. CHA/S with various concentrations of EW (10 and 30 wt.%) effectively increased pore size and porosity. XRD spectra confirmed that sago and EW in CHA nanocomposite stable the crystal structure. FTIR spectrum shows protein phosphorylation in CHA nanocomposite due to PO₄^3- ion exchange. In-vitro bioactivity of CHA-S10 (MTT assay) showed increased cell viability and optical density (OD; 24-48 h) to control. Antibacterial activity of CHA-S10 and CHA/S (control) against bacteria associated with periodontal disease and bone infection (Actinobacillus actinomycetemcomitans [A. actinomycetemcomitans], Porphyromonas gingivalis [P. gingivalis], Fusobacterium nucleatum [F. nucleatum; gram negative], and Staphylococcus aureus [S. aureus; gram positive]) by disc diffusion method showed that CHA-S10 and CHA/S had strong antibacterial activity. In conclusion, EW's properties had proven the CHA/S/EW as bone grafts, effectively increasing pore size, porosity, biocompatibility, and strong antibacterial properties.

Silver Nanoparticles as Chlorhexidine and Metronidazole Drug Delivery Platforms: Their Potential Use in Treating Periodontitis

Purpose

Materials and Methods

Results

Conclusion

In vitro bioactivity of 3D microstructure hydroxyapatite/collagen based-egg white as an antibacterial agent

The present study aims to design 3D scaffold hydroxyapatite (HA)/collagen (Coll) based egg-white (EW) as antibacterial properties. The calcium source in HA synthesis derived from the Pinctada maxima shell cultivated on Bali Island has proven biocompatibility, and the compressive strength exceeded human bone. HA synthesis by precipitation with heat treatment in oven-dried at 80°C (HA-80) and annealed at 900°C (HA-900), has crystallinity 48% and 85%, respectively, were used for scaffold design. The physicochemical properties of X-ray diffractometer spectra showed that increasing temperature affected the crystallinity and HA phase formed. Furthermore, the crystal structure of HA changed in nanocomposite due to the substitution of Coll and EW, and the Fourier transform infrared spectroscopy spectra confirmed that the absorption peak of the phosphate group (1027-1029 cm^-1 ) decreased intensity, presumably by protein binding of EW and Coll. The cell viability of HA/Coll/EW in 24, 48, and 72 h incubation period was 112.34 ± 4.36, 104.89 ± 3.41, 72.88 ± 6.85, respectively. The decreases of cell viability due to high cell density and reduced nutrients in wells. Antibacterial activity of HA/Col/EW exhibited a strong zone of inhibition against bacteria causing periodontitis; Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, and Staphylococcus aureus.

Antimicrobial Resistance and Molecular Epidemiological Characteristics of Methicillin-Resistant and Susceptible Staphylococcal Isolates from Oral Cavity of Dental Patients and Staff in Northern Japan

The acquisition of drug resistance and virulence by staphylococcal species colonizing humans is a growing public health concern. The present study was conducted to investigate the prevalence, antimicrobial resistance and genetic characteristics of Staphylococcus isolates from the oral cavity and skin (hand) of systemically healthy subjects with dental disease and dental staff in northern Japan. Among a total of 133 subjects (91 patients and 42 staff), 87 coagulase-positive Staphylococcus (83 S. aureus/4 S. argenteus) and 162 coagulase-negative Staphylococcus (CoNS) isolates were recovered from 59 (44.4%) and 95 (71.4%) subjects, respectively. Three oral isolates were methicillin-resistant S. aureus (MRSA) (3.6%, 3/83) that were genotyped as ST8-SCCmec-IVl, ST4775(CC1)-SCCmec-IVa and ST6562(CC8)-SCCmec-IVa. Remarkably, the ST6562 isolate harbored PVL genes on ΦSa2usa and type I ACME (arginine catabolic mobile element). Four methicillin-susceptible isolates were identified as S. argenteus belonging to ST1223 and ST2250, which harbored enterotoxin genes egc-2 and sey, respectively. Among the fourteen CoNS species identified, methicillin-resistant (MR) isolates were detected in five species (11 isolates, 13.3% of CoNS), with S. saprophyticus and S. haemolyticus being the most common. ACME was prevalent in only S. epidermidis and S. capitis. These findings indicated the potential distribution of USA300 clone-like MRSA, toxigenic S. argenteus and MR-CoNS in the oral cavity of dental patients.

Pathogenic Microbial Profile and Antibiotic Resistance Associated with Periodontitis

Abstract

Phenotyping based on conventional microbiological, physiological, and molecular analysis by using ARDRA technique was developed with the aim to assess the pathogenic microbial load associated with different stages of the periodontal disease. In addition, in the face of the global issue of antimicrobial resistance, the isolated bacterial strains were evaluated for their antibiotic susceptibility profile. The pathogenic bacterial community was predominantly of Gram-negative strains (66.66%). The most common species were Citrobacter freundii, Bacillus sp., Raoutella sp., Klebsiella ozaenae and Pseudomonas sp. However, except for the healthy control group, Staphylococcus spp. was isolated from all stages of periodontitis. Multidrug resistance to beta-lactam antibiotics was observed for Streptococcus pneumoniae, Raoutella sp. and Enterococcus avium. Here, we verify a statistically significant relationship between periodontitis stages and the diversity of the bacterial community. Patients with periodontitis showed a more diverse and numerous bacterial community compared to healthy patients. In this sense, we reinforce that biofilms that harbour multidrug-resistant bacteria are a major concern in relation to restoring patient health. Thus, prophylactic measures for maintaining oral health are still the best option for reduce the risk of disease.

Graphic Abstract

Oral microbiome in down syndrome and its implications on oral health

Introduction: The oral cavity harbors an abundant and diverse microbial community (i.e. the microbiome), whose composition and roles in health and disease have been the focus of intense research. Down syndrome (DS) is associated with particular characteristics in the oral cavity, and with a lower incidence of caries and higher incidence of periodontitis and gingivitis compared to control populations. However, the overall composition of the oral microbiome in DS and how it varies with diverse factors like host age or the pH within the mouth are still poorly understood. Methods: Using a Citizen-Science approach in collaboration with DS associations in Spain, we performed 16S rRNA metabarcoding and high-throughput sequencing, combined with culture and proteomics-based identification of fungi to survey the bacterial and fungal oral microbiome in 27 DS persons (age range 7–55) and control samples matched by geographical distribution, age range, and gender.

Results: We found that DS is associated with low salivary pH and less diverse oral microbiomes, which were characterized by lower levels of Alloprevotella, Atopobium, Candidatus Saccharimonas, and higher amounts of Kingella, Staphylococcus, Gemella, Cardiobacterium, Rothia, Actinobacillus, and greater prevalence of Candida.

Conclusion: Altogether, our study provides a first global snapshot of the oral microbiome in DS. Future studies are required to establish whether the observed differences are related to differential pathology in the oral cavity in DS.

Presence of egc-positive major clones ST 45, 30 and 22 among methicillin-resistant and methicillin-susceptible oral Staphylococcus aureus strains

The oral cavity may comprise a significant reservoir for Staphylococcus aureus but the data on molecular epidemiology and clonal distribution of oral strains are really scarce. This study aimed to evaluate the clonal relatedness in S. aureus isolated from oral cavity and their relationship with carriage of virulence genes, and antimicrobial resistance profiles. A total of 139 oral S. aureus isolates were obtained from 2327 analysed oral samples of dental patients. Antimicrobial susceptibility testing was performed. Isolates were characterized using protein A gene (spa) typing, spa-CC clonal complexes, toxin genes and SCCmec typing for MRSA. High resistance rates for penicillin, tetracycline and gentamicin were detected, respectively 58.3%, 42.4%, and 35.2%. Twelve (8.6%) S. aureus isolates were identified as MRSA. All of MRSA isolates were mecA-positive and mecC-negative. SCCmec IV was the most common type (66.7%), which was typical for community-acquired MRSA (CA-MRSA). Overall, the enterotoxin gene cluster (egc) was the most frequent detected virulence factor (44.9%), both in MSSA and MRSA isolates. Presence of genes encoding for the enterotoxins (sea, seb, sec, seh, sek), exfoliative toxin A (eta), and toxic shock syndrome toxin-1 (tst) was also observed. Strains carrying lukS-PV/lukF-PV genes belonged to SCCmecV- spa type t437. The most prevalent spa types were t091, t015, t084, t002, t571, and t026 among all 57 identified. Spa types, including 3 new ones, grouped in 6 different spa-CC clonal complexes, with four major dominated; CC45, CC30, CC5, and CC15. This study demonstrated that both methicillin-susceptible and methicillin-resistant major European clones of S. aureus could be isolated from the oral cavity of dental patients, with the emergence of PVL-positive CA-MRSA strains. The oral cavity should be considered as a possible source of toxigenic egc-positive S. aureus strains, in terms of potential risk of cross-infection and dissemination to other body sites.

Distribution of Antibiotic Resistance Genes in the Saliva of Healthy Omnivores, Ovo-Lacto-Vegetarians, and Vegans

Food consumption allows the entrance of bacteria and their antibiotic resistance (AR) genes into the human oral cavity. To date, very few studies have examined the influence of diet on the composition of the salivary microbiota, and even fewer investigations have specifically aimed to assess the impact of different long-term diets on the salivary resistome. In this study, the saliva of 144 healthy omnivores, ovo-lacto-vegetarians, and vegans were screened by nested PCR for the occurrence of 12 genes conferring resistance to tetracyclines, macrolide-lincosamide-streptogramin B, vancomycin, and β-lactams. The tet(W), tet(M), and erm(B) genes occurred with the highest frequencies. Overall, no effect of diet on AR gene distribution was seen. Some differences emerged at the recruiting site level, such as the higher frequency of erm(C) in the saliva of the ovo-lacto-vegetarians and omnivores from Bologna and Turin, respectively, and the higher occurrence of tet(K) in the saliva of the omnivores from Bologna. A correlation of the intake of milk and cheese with the abundance of tet(K) and erm(C) genes was seen. Finally, when the occurrence of the 12 AR genes was evaluated along with geographical location, age, and sex as sources of variability, high similarity among the 144 volunteers was seen.

Marked virulence and azole resistance in Candida albicans isolated from patients with periodontal disease

Candida albicans is an opportunistic fungus frequently associated with periodontal diseases. The objective of this study was to determine the expression patterns of virulence genes associated with those of azole resistance among the strains of C. albicans isolated from patients with periodontal disease. We isolated 80 strains of C. albicans from patients with periodontal disease enrolled from two dental clinics and their antifungal susceptibilities were evaluated using the disc diffusion method. C. albicans and its virulence genes were identified using PCR. The expressions of the virulence genes of C. albicans were analyzed using real-time PCR post in vitro infection of the cell line A549. The phenotype for resistance against azoles such as ketoconazole and fluconazole was observed in all analyzed strains (n = 80), which coincided with the high frequency of occurrence of the genes CDR1 and MDR1 associated with resistance. The frequencies of detection and expression of the genes HWP1 (47/15), ALS1 (80/66), ALS3 (70/30), LIP1 (78/44), LIP4 (77/65), LIP5 (79/58), LIP6 (79/58), PLB1 (79/65), and PLB2 (80/66) were found to be higher in the strains of C. albicans isolated from patients with moderate periodontitis and different expression patterns associated with those for azole resistance were identified. It could be elucidated that the high expression of virulence markers associated with azole resistance in C. albicans might be contributing to the chronicity of periodontal infections.

Development and Evaluation of a Polyvinylalcohol -Cellulose Derivative-Based Film with Povidone-Iodine Predicted for Wound Treatment

The aim of this study was to develop and assess a polyvinyl alcohol-cellulose derivatives-based film with incorporated povidone-iodine (PVP-I) predicted for applications in the treatment of periodontitis. Films were fabricated by solvent-casting, and their physical characteristics, such as their surface and structure morphology, mechanical properties, and disintegrating time, were evaluated. For in vitro iodine release studies and evaluation, the antimicrobial activity was tested using a modified disc diffusion method against five microbial strains. For further use, we selected the film with polyvinyl alcohol-hydroxypropyl methylcellulose (PVA/HPMC_B) based on acceptable physicochemical properties. To assess the subacute toxicity of the film composition, the tissue regeneration process was tested in rats and compared to a conventional dressing commonly used in wound healing (Spongostan). Seven days after implantation, dorsal skin sections and blood samples (n = 10, in total n = 30) were examined. The wound area, epithelium, and dermis were evaluated microscopically, while the blood collected from the rats underwent biochemical analysis. The blood biochemistry results were comparable in all three groups. No significant histological differences between the Spongostan and the placebo film developed after subcutaneous implantation were observed. In contrast, the inflammation stage was reduced and the “scar” in the dermis was smaller when PVP-I and PVA/HPMC_B films were used. A smaller local inflammatory response inflicted less tissue damage, leading to the activation of subsequent regeneration phases and restoration of the area to its original state. The results obtained confirmed that PVP-I incorporated into PVA-hydroxypropyl methylcellulose film is a promising drug carrier, working faster and more effectively than the other two dressing materials evaluated. These developments provide a promising alternative in tissue regeneration and the wound healing process.

Emergence of community-acquired methicillin-resistant Staphylococcus aureus EMRSA-15 clone as the predominant cause of diabetic foot ulcer infections in Portugal

Methicillin-resistant Staphylococcus aureus (MRSA) are often found in infected diabetic foot ulcers, in which the prevalence may reach 40%. These complications are one of the main causes of morbidity in diabetic patients. The objectives of this study were to investigate the prevalence and antimicrobial resistance of MRSA strains in infected diabetic foot ulcers and to characterize their genetic lineages. Samples collected from 42 type 2 diabetic patients, presenting infected foot ulcers, were seeded onto ORSAB plates with 2 mg/L of oxacillin for MRSA isolation. Susceptibility to 14 antimicrobial agents was tested by the Kirby-Bauer disk diffusion method. The presence of resistance genes, virulence factors, and the immune evasion cluster system was studied by PCR. All isolates were characterized by MLST, accessory gene regulator (agr), spa, and staphylococcal chromosomal cassette mec (SCCmec) typing. Twenty-five MRSA strains were isolated. All isolates showed resistance to penicillin and cefoxitin. Sixteen isolates showed phenotypic resistance to erythromycin being 7 co-resistant to clindamycin. Resistance to trimethoprim-sulfamethoxazole was found in 2 isolates harboring the dfrA and dfrG genes. The IEC genes were detected in 80% of isolates, 16 of which were ascribed to IEC-type B. Isolates were assigned to 12 different spa types. The MLST analysis grouped the isolates into 7 sequence types being the majority (68%) ascribed to SCCmec type IV. In this study, there was a high prevalence of the EMRSA-15 clone presenting multiple resistances in diabetic foot ulcers making these infections complicated to treat leading to a higher morbidity and mortality in diabetic patients.

Staphylococcus aureus induces COX-2-dependent proliferation and malignant transformation in oral keratinocytes

The COX-2/PGE₂ axis can play roles in mediating the progression of tumor. COX-2 induction was observed in oral cancer. In our previous study, we found Staphylococcus aureus, a pathogen prevalent in oral cancer, can activate the COX-2/PGE₂ pathway in human oral keratinocyte (HOK) cells. Here, we investigated the proliferation of HOK cells affected by COX-2 induction and the role of COX-2 induction in the malignant transformation of HOK cells. We found S. aureus was able to facilitate HOK cell proliferation through upregulating COX-2 expression. With the induction of COX-2, expression of oral cancer-associated genes cyclin D1 was upregulated and p16 was downregulated. Transcriptome analysis showed that the “NF−kappa B signaling pathway” and “TNF signaling pathway” had the highest enrichment of differentially expressed genes (DEGs) with COX-2 over-expression. Seven upregulated genes (jun, tlr4, cxcl1, lif, cxcl3, tnfrsf1β, and il1β) in these two pathways were critical for the increased proliferation of HOK cells and might be associated with COX-2. Malignant transformation of cells was evaluated by soft agar colony formation assay and S. aureus infection promoted HOK cell colony formation. These results suggest the potential of S. aureus to induce the infection-associated malignant transformation of oral epitheliums through COX-2 activation.

Frequency and expression of genes involved in adhesion and biofilm formation in Staphylococcus aureus strains isolated from periodontal lesions

BACKGROUND/PURPOSE

The aim of this study was to characterize the Staphylococcus aureus strains isolated from periodontal lesions of patients, to determine the expression of genes involved in cell adhesion upon their infection of human epithelial cells using an in vitro model, its biofilm formation, and its resistance to antibiotics.

METHODS

S. aureus was analysed by PCR, Kirby-Bauer, and pulsed-field gel electrophoresis (PFGE), measuring gene expression by real-time PCR after infection of human cells in vitro.

RESULTS

S. aureus was identified in 18.6% (50/268) of the samples. All strains (n = 50) possessed the virulence genes spa (Staphylococcal protein A), coa (coagulase), and icaAB (intercellular adhesin); 96% (n = 48) possessed clfB (clumping factor B), and 88% (n = 44) possessed ebps (elastin-binding protein) and sdrD (serine aspartate repeat protein D). All strains were resistant to methicillin, ampicillin, dicloxacillin, cefotaxime, and penicillin, and were multidrug resistant to 6-12 antibiotics. PFGE analysis showed 37 different pulsed-field types and most strains (60.4%) had a unique pulsed-field type. Twenty-four distinct combinations of virulence genes and antibiotic-resistant phenotypes were identified.

CONCLUSION

Although S. aureus has been considered a transient member of the oral microbiota, our results indicate a high-level expression of virulence genes and multidrug resistance in the strains isolated from periodontal lesions. These strains might complicate the successful treatment of the disease.

Candida-Bacteria Interactions: Their Impact on Human Disease

Candida species are the most common infectious fungal species in humans; out of the approximately 150 known species, Candida albicans is the leading pathogenic species, largely affecting immunocompromised individuals. Apart from its role as the primary etiology for various types of candidiasis, C. albicans is known to contribute to polymicrobial infections. Polymicrobial interactions, particularly between C. albicans and bacterial species, have gained recent interest in which polymicrobial biofilm virulence mechanisms have been studied including adhesion, invasion, quorum sensing, and development of antimicrobial resistance. These trans-kingdom interactions, either synergistic or antagonistic, may help modulate the virulence and pathogenicity of both Candida and bacteria while uniquely impacting the pathogen-host immune response. As antibiotic and antifungal resistance increases, there is a great need to explore the intermicrobial cross-talk with a focus on the treatment of Candida-associated polymicrobial infections. This article explores the current literature on the interactions between Candida and clinically important bacteria and evaluates these interactions in the context of pathogenesis, diagnosis, and disease management.