Unveiling the Relevance of the Oral Cavity as a Staphylococcus aureus Colonization Site and Potential Source of Antimicrobial Resistance

Clinical and genetic analysis of oral and nasal staphylococcus aureus isolates in dental patients

Staphylococcus aureus is a common bacterium that sometimes causes various pyogenic diseases. Methicillin resistant S. aureus (MRSA) infections are particularly difficult to treat. Recently, MRSA has been spreading in the community, so it is important to determine the prevalence of MRSA in the community and to conduct epidemiological studies from genetic and statistical perspectives. In this study, S. aureus/MRSA was isolated from the oral and nasal cavities of 504 dental patients (65 inpatients and 439 outpatients). Sixty-two S. aureus strains and 9 MRSA strains were isolated from the oral cavity, and 112 S. aureus strains and 21 MRSA strains were isolated from the nasal cavity. Multi-locus sequence typing (MLST) analysis showed ST8 was high (18 isolates) among 30 MRSA isolates, whereas among 144 methicillin sensitive isolates, ST15 (25 isolates) and ST8 (20 isolates) were high. Statistical analysis of the patients' clinical status revealed a correlation between oral S. aureus and denture use. Among the 34 patients from whom S. aureus was isolated from both sites, 25 had the same ST, and 23 showed below 40 single-nucleotide polymorphisms which are considered to be identical strains. Our study revealed various properties of S. aureus/MRSA in the oral and nasal cavities as commensals.

Antimicrobial Activity of Poly(methyl methacrylate) Doped with CuO and ZnO Nanoparticles

Oral health represents a significant factor in general health and life quality. A significant number of people are affected by tooth loss during their lifetimes, especially in the older population. Poly(methyl methacrylate) (PMMA) resins are the preferred option for replacing missing teeth due to the material stability, easy handling, low toxicity, and most importantly biocompatibility with human tissue. Even though PMMA is the preferable material for denture preparation, it is susceptible to microbial colonization, which can induce the development of oral infections. This study aimed to increase the antimicrobial effect of PMMA and compare the antimicrobial properties of PMMA incorporated with different amounts (2 and 5 wt %) of zinc oxide (ZnO; primary size 62.4 nm ± 16.7 nm) and copper oxide (CuO; primary size 434.0 nm ± 118.5 nm) nanoparticles to determine their antimicrobial effects on Gram-positive bacteria Staphylococcus aureus and yeast Candida albicans-pathogenic microbes often found on dentures. To understand the adhesion of microorganisms to PMMA-modified surfaces, the following surface properties were measured: roughness, contact angle, and ζ potential. In addition, CIE (the International Commission on Illumination) color parameters of the materials were determined. The bacterial adhesion was measured by viable plate counts and scanning electron microscopy. Our study showed that 5 wt % ZnO added to PMMA yields a promising denture material that is esthetically acceptable and shows antimicrobial properties toward both, Staphylococcus aureus and Candida albicans.

The effect of soaking heat-polymerized acrylic resin denture base in avocado seed extract ( Persea americana Mill.) on the inhibition of denture-plaque microorganisms biofilm growth

Background

Heat polymerized acrylic (HPA) resins are known to have high porosity that contributes to increased surface roughness and microcrack formation in stress areas. This facilitates the attachment and growth of polymicrobial biofilms contributing to increased antimicrobial resistance. This research aims to study avocado seeds effect on denture-plaque microorganism mono-species and polymicrobial biofilm on HPA resin.

Methods

This study uses 144 samples (n=144), namely HPA resin discs covered with mono-species and polymicrobial biofilms. The discs are soaked for 8 hours in the 5%, 10%, 15%, 20% avocado seed extract, positive control (alkaline peroxide), and negative control (aquadest). Each disc is shaken with a vortex mixer for 1 minute, and 100 μL is added into 96-well microplates with three times repetition and incubated for 24 hours. A microtiter plate biofilm formation assay is then conducted. The inhibition values are determined from the percentage inhibition value formula which requires absorption values from a microplate reader (595 nm). The research data are analyzed using a univariant test, and a one-way ANOVA test, accompanied by Welch ANOVA on non-homogenous data.

Results

In this research, it is found that the MBIC 50 of avocado seed extract against the mono-species of C. albicans (5%), C. glabrata (5%), A. odontolyticus (15%), S. gordonii (15%), S. aureus (10%), while against polymicrobial was 20%. There is a significant effect of soaking HPA resin in avocado seed extract on the inhibition of mono-species and polymicrobial biofilms with a value of p<0.001 (p<0.05).

Conclusion

The MBIC 50 of avocado seed extract in polymicrobial biofilm group is higher than that in the mono-species biofilm groups. Hence, 20% avocado seed extract is concluded as the effective concentration to inhibit denture-plaque microorganism biofilm.

Temporalis muscle abscess with intracranial invasion from odontogenic infection: a case report

Odontogenic infections leading to masticator space abscesses with intracranial extension are rare occurrences. Reported cases of masticator space abscesses with direct intracranial invasion typically originate from medial masticator space abscesses, spreading by eroding the skull base foramen or through the walls of the sinus or orbit. This report presents a unique case of a lateral masticator space abscesses that extended intracranially. The case highlights the uncommon pathway of infection spread and underscores the importance of early recognition and intervention in preventing severe complications.

Two draft genome assemblies of Staphylococcus aureus strains isolated from a cheek swab of a healthy female participant

Staphylococcus aureus is an opportunistic pathogen often commensal within the nasal and oral cavities. Here we present the genomes of S. aureus O139-S and O139-NS, both isolated from the cheek swab of a healthy female participant. While found in the same sample, the two strains displayed distinct colony morphologies.

Oral Staphylococcus Species and MRSA Strains in Patients with Orofacial Clefts Undergoing Surgical Rehabilitation Diagnosed by MALDI-TOF MS

This study investigated the occurrence and dynamics of oral Staphylococcus species in patients with orofacial clefts undergoing surgical rehabilitation treatment. Patients (n = 59) were statistically stratified and analyzed (age, gender, types of orofacial clefts, surgical history, and types of previous surgical rehabilitation). Salivary samples were obtained between hospitalization and the return to the specialized medical center. Microbiological diagnosis was performed by classical methods, and MALDI-TOF MS. MRSA strains (SCCmec type II, III, and IV) were characterized by the Decision Tree method. A total of 33 (55.9%) patients showed oral staphylococcal colonization in one, two, or three sampling steps. A high prevalence has been reported for S. aureus (including HA-, MRSA and CA-MRSA), followed by S. saprophyticus, S. epidermidis, S. sciuri, S. haemolyticus, S. lentus, S. arlettae, and S. warneri. The dynamics of oral colonization throughout surgical treatment and medical follow-up may be influenced by (i) imbalances in staphylococcal maintenance, (ii) efficiency of surgical asepsis or break of the aseptic chain, (iii) staphylococcal neocolonization in newly rehabilitated anatomical oral sites, and (iv) total or partial maintenance of staphylococcal species. The highly frequent clinical periodicity in specialized medical and dental centers may contribute to the acquisition of MRSA in these patients.

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.

Oral and rectal colonization of methicillin-resistant Staphylococcus aureus in long-term care facility residents and their association with clinical status

Staphylococcus aureus is a commensal bacterium in humans, but it sometimes causes opportunistic infectious diseases such as suppurative skin disease, pneumonia, and enteritis. Therefore, it is important to determine the prevalence of S. aureus and methicillin-resistant S. aureus (MRSA) in individuals, especially older adults. In this study, we investigated the prevalence of S. aureus and MRSA in the oral cavity and feces of residents in long-term care facilities (LTCFs). S. aureus was isolated from the oral cavity of 61/178 (34.3%) participants, including 28 MRSA-positive participants (15.7%), and from the feces of 35/127 (27.6%) participants, including 16 MRSA-positive participants (12.6%). S. aureus and MRSA were isolated from both sites in 19/127 individuals (15.0%) and 10/127 individuals (7.9%), respectively. Among 19 participants with S. aureus isolation from both sites, 17 participants showed the same sequence type (ST) type. Then, we analyzed the correlation of S. aureus and MRSA in the oral cavity and rectum with the participant's condition. S. aureus and MRSA positivity in the oral cavity was significantly related to tube feeding, while there was no correlation of rectal S. aureus/MRSA with any factors. Our findings regarding the oral inhabitation of MRSA and its risk factors indicate the importance of considering countermeasures against MRSA infection in LTCFs.