Methicillin-resistant Staphylococcus aureus among dental patients

Staphylococcus aureus nasal colonization among dental health care workers in Northern Germany (StaphDent study)

Methicillin-resistant Staphylococcus aureus (MRSA) can colonize dental patients and students, however, studies on the prevalence of MRSA and methicillin-susceptible S. aureus (MSSA) among dental health care workers (DHCW) including use of personal protective equipment (PPE) are scarce. We conducted an observational study (StaphDent study) to (I) determine the prevalence of MRSA and MSSA colonization in DHCW in the region of Mecklenburg Western-Pomerania, Germany, (II) resolve the S. aureus population structure to gain hints on possible transmission events between co-workers, and (III) clarify use of PPE. Nasal swabs were obtained from dentists (n = 149), dental assistants (n = 297) and other dental practice staff (n = 38). Clonal relatedness of MSSA isolates was investigated using spa typing and, in some cases, whole genome sequencing (WGS). PPE use was assessed by questionnaire. While 22.3% (108/485) of the participants were colonized with MSSA, MRSA was not detected. MSSA prevalence was not associated with size of dental practices, gender, age, or duration of employment. The identified 61 spa types grouped into 17 clonal complexes and four sequence types. Most spa types (n = 47) were identified only once. In ten dental practices one spa type occurred twice. WGS data analysis confirmed a close clonal relationship for 4/10 isolate pairs. PPE was regularly used by most dentists and assistants. To conclude, the failure to recover MRSA from DHCW reflects the low MRSA prevalence in this region. Widespread PPE use suggests adherence to routine hygiene protocols. Compared to other regional HCW MRSA rates the consequent usage of PPE seems to be protective.

Nasal conveyance of Methicillin-resistant Staphylococcus aureus (MRSA) strains among dental professionals with varying levels of clinical exposure: A comparative study

OBJECTIVE

Any control program for MRSA requires identifying the whole hospital reservoir. The likelihood of conveyance of MRSA may be higher in dental settings. Hence, the aim was to compare the nasal conveyance MRSA among dental professionals with varying levels of clinical exposure in a tertiary dental hospital in South India.

METHODS

A total of 81 volunteers were stratified based on the number of years of clinical exposure. The nasal swabs were subjected to catalase and coagulase tests as well as antibiotic susceptibility test. Chi- Square test was done to compare the different types of organisms isolated from dental professionals with varied levels of clinical exposure.

RESULTS

Out of the total 81 isolates, 62.96% of the isolates were MSCONS (Methicillin sensitive coagulase negative staphylococcus), 20.98% of them were MRCONS (Methicillin resistant coagulase negative staphylococcus), 9.87% were MSSA (Methicillin sensitive staphylococcus aureus) and 3.7% were MRSA positive and 2.46% were other gram negative organisms.

CONCLUSIONS

MRCONS, MSSA and MRSA were shown to increase with an increase in the clinical exposure years.

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.

Higher nasal carriage rate of methicillin-resistant Staphylococcus aureus among dental students who have clinical experience

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) has been isolated from dental clinical surfaces, dental patients, and dental health care professionals. The authors conducted a study to determine the prevalence rate of nasal MRSA colonization among dental school students and to identify the characteristics of the isolated strains.

METHODS

The authors collected nasal samples from 159 dental students. The authors performed mecA gene detection, staphylococcal cassette chromosome mec (SCCmec) typing, and antimicrobial susceptibility tests on each sample. The authors compared the results of 2 groups (students who had clinical experience and students who did not have clinical experience).

RESULTS

Five (3.1%) dental students had MRSA colonization, as confirmed by the presence of the mecA gene in the nasal cavity. Prior clinical experience was associated significantly with nasal MRSA carriage (P < .05). Four of the strains were SCCmec type IV, and 1 strain was SCCmec type I. All isolates were resistant to amoxicillin and clavulanic acid, imipenem, and oxacillin, but were susceptible to several antimicrobial agents including mupirocin, trimethoprim and sulfamethoxazole, and rifampin. The nasal MRSA colonization was eradicated with the use of mupirocin ointment.

CONCLUSIONS

Nasal MRSA colonization occurs in some dental students, especially those who have clinical experience.

PRACTICAL IMPLICATIONS

Education about MRSA colonization and transmission, as well as infection prevention and control measures is necessary for dental students, especially when they participate in clinical practice.

Low methicillin-resistant Staphylococcus aureus carriage rate among Italian dental students

We assessed methicillin-resistant Staphylococcus aureus (MRSA) carriage rate among dental students from an Italian university. A total of 157 subjects participated (67 preclinical students and 90 clinical students); samples were collected from the nose, mouth, and skin. Five preclinical students and 0 clinical students were MRSA-positive. Carriage rates were 3.2% (95% confidence interval [CI], 0.4%-6.0%) overall, 7.5% (95% CI, 1.2%-13.8%) in preclinical students and 0% in clinical students. There were 2 MRSA clusters among the preclinical students: 3 second-year and 2 first-year students, who sat close to one another in the classroom the day of the sample. MRSA carriage was not associated with dental health care. The pooled carriage rate among dental students was assessed to obtain a reliable figure of carriage rate unaffected by local conditions. The 4 published surveys were pooled, and the fixed-effects method was used. Among the 484 dental students, the pooled carriage rate was 4.1% (95% CI, 2.4%-5.8%).