Isolation and Antimicrobial Resistance ofStaphylococcus aureusIsolates in a Dental Clinic Environment

Can aerosols-generating dental, oral and maxillofacial, and orthopedic surgical procedures lead to disease transmission? An implication on the current COVID-19 pandemic

Various dental, maxillofacial, and orthopedic surgical procedures (DMOSP) have been known to produce bioaerosols, that can lead to the transmission of various infectious diseases. Hence, a systematic review (SR) aimed at generating evidence of aerosols generating DMOSP that can result in the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), further investigating their infectivity and assessing the role of enhanced personal protective equipment (PPE) an essential to preventing the spreading of SARS-CoV-2 during aerosol-generating procedures (AGPs). This SR was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA) guidelines based on a well-designed Population, Intervention, Comparison, Outcomes and Study (PICOS) framework, and various databases were searched to retrieve the studies which assessed potential aerosolization during DMOSP. This SR included 80 studies (59 dental and 21 orthopedic) with 7 SR, 47 humans, 5 cadaveric, 16 experimental, and 5 animal studies that confirmed the generation of small-sized < 5 μm particles in DMOSP. One study confirmed that HIV could be transmitted by aerosolized blood generated by an electric saw and bur. There is sufficient evidence that DMOSP generates an ample amount of bioaerosols, but the infectivity of these bioaerosols to transmit diseases like SARS-CoV-2 generates very weak evidence but still, this should be considered. Confirmation through isolation and culture of viable virus in the clinical environment should be pursued. An evidence provided by the current review was gathered by extrapolation from available experimental and empirical evidence not based on SARS-CoV-2. The results of the present review, therefore, should be interpreted with great caution.

Aerosol generated by dental procedures: A scoping review

BACKGROUND

The current pandemic has raised awareness of aerosol dispersion in dental offices. This scoping review was conducted to assess the amount and spread of aerosol generated by dental procedures.

METHODS

This scoping review followed the PRISMA-ScR protocol and was conducted by searching multiple databases adopting a core search structure for each database. Detailed eligibility criteria were applied. The authors placed no restrictions on study design, year of publication, and study location. The literature search was updated on September 15, 2021.

RESULTS

A total of 51 papers were included in this scoping review. The risk of bias assessment was not conducted as per guidelines. The majority of studies found microorganisms, bloodstains, splatters of aerosol, and particles in the air part of the search strategy. Publication dates ranged from 1969 to 2021. Data came from different dental settings locations. Several factors were identified that have an effect on the amount and spread of the aerosol and spatter.

CONCLUSION

Although it is clear that the microbial contamination occurred mainly during aerosol-generating dental procedures, our understanding of the contamination level, spread, and half-life are limited.

A novel dental biosafety device to control the spread of potentially contaminated dispersion particles from dental ultrasonic tips

Strategies to return to dental practice in pandemic times is a new challenge due to the generation and spread of potentially contaminated dispersion particles (PCDP) that may contain the SARS-CoV-2, the etiological factor of the COVID-19 disease. Due to the significant dispersion of PCDP in the dental environment, the use of equipment such as ultrasonic tips have been inadvisable during the pandemic. Several clinical procedures, however, benefit from the use of such equipment. Thus, using a microbial dispersion model of PCDP, the aim of this study was to compare the dispersion caused by the dental drill (DD) an ultrasonic tip (UT) alone and the UT coupled with a Spray control (SC) device. The DD, UT (with or without the SC) were activated for one minute having had the water from the reservoir replaced with a suspension of Lactobacillus casei Shirota (1.5 x 10⁸ CFU/mL). Petri dishes containing MRS agar were positioned at 50cm, 100cm and 150cm from the headrest of the dental chair at different angles (0 degree and 90 degrees). At 50 cm, the mean CFU (standard deviation) of L. casei Shirota was 13554.60 (4071.03) for the DD, 286.67 (73.99) for the US (97.89% reduction), and 4.5 (0.58) CFU for the UT-SC (p < 0.0001), establishing a further 98.43% reduction between UT and UT with SC. The UT with SC model proved effective in reducing dispersion from the UT, endorsing its use as an additional strategy to reduce PCDP in the dental environment in times of pandemic.

Detection of Staphylococcus aureus (MRSA/MSSA) in surfaces of dental medicine equipment

Methicillin-Resistant Staphylococcus aureus (MRSA) represents one of the major causes of nosocomial infections, leading to high mortality. Surfaces in clinics, as well as the attending uniform and the hands of the dental doctor can be MRSA reservoirs. Having this in mind, the purpose of this study was to evaluate the presence of Methicillin-Sensitive Staphylococcus aureus (MSSA) and MRSA on dental medicine equipment surfaces. 354 Samples were collected from six equipment surfaces in six attendance areas before and after patient consultation and cultured in a selective medium. Polymerase Chain Reaction (PCR) was used to confirm the identity of bacterial strains as MRSA or MSSA. Data analysis was performed with chi-square tests with Bonferroni correction. It was observed 55.6% of uncontaminated samples. Contamination was: 17.5% MRSA (5.9% of samples collected before patient attendance and 11.6% after); 39.3% MSSA (14.1% collected before and 25.2% after). The prevalence of MRSA and MSSA was significantly higher after patient care. Integrated Clinic represented the most contaminated attendance area (MRSA − 41.7%, MSSA − 51.2%), the chair arm rest was the most contaminated surface for MRSA (29.7%) and the dental spittoon the most contaminated surface for MSSA (23.5%). Although a low level of contamination was observed, dental clinics, through patients possibly carrying bacteria, may be reservoirs for MRSA and MSSA transmission, and might contribute to potential nosocomial infections.

What's on your keyboard? A systematic review of the contamination of peripheral computer devices in healthcare settings

OBJECTIVE

To determine the extent and type of microbial contamination of computer peripheral devices used in healthcare settings, evaluate the effectiveness of interventions to reduce contamination of these devices and establish the risk of patient and healthcare worker infection from contaminated devices.

DESIGN

Systematic review METHODS: We searched four online databases: MEDLINE, CINAHL, Embase and Scopus for articles reporting primary data collection on contamination of computer-related equipment (including keyboards, mice, laptops and tablets) and/or studies demonstrating the effectiveness of a disinfection technique. Pooling of contamination rates was conducted where possible, and narrative synthesis was used to describe the rates of device contamination, types of bacterial and viral contamination, effectiveness of interventions and any associations between device contamination and human infections.

RESULTS

Of the 4432 records identified, a total of 75 studies involving 2804 computer devices were included. Of these, 50 studies reported contamination of computer-related hardware, and 25 also measured the effects of a decontamination intervention. The overall proportion of contamination ranged from 24% to 100%. The most common microbial contaminants were skin commensals, but also included potential pathogens including methicillin-resistantStaphylococcus aureus, Clostridiumdifficile, vancomycin-resistantenterococci and Escherichia coli. Interventions demonstrating effective decontamination included wipes/pads using isopropyl alcohol, quaternary ammonium, chlorhexidine or dipotassium peroxodisulfate, ultraviolet light emitting devices, enhanced cleaning protocols and chlorine/bleach products. However, results were inconsistent, and there was insufficient data to demonstrate comparative effectiveness. We found little evidence on the link between device contamination and patient/healthcare worker colonisation or infection.

CONCLUSIONS

Computer keyboards and peripheral devices are frequently contaminated; however, our findings do not allow us to draw firm conclusions about their relative impact on the transmission of pathogens or nosocomial infection. Additional studies measuring the incidence of healthcare-acquired infections from computer hardware, the relative risk they pose to healthcare and evidence for effective and practical cleaning methods are needed.

The assessment of adherence to infection control in oral radiology using newly developed and validated questionnaire (QICOR)

OBJECTIVES:

To assess the infection control in oral radiology among radiologists and dentists of diverse dentistry clinical specialties and among dentistry students.

METHODS:

A Questionnaire on Infection Control in Oral Radiology was applied to 1006 dentists and 1203 dentistry students. For assessment of infection control, the scores of the questionnaire were dichotomized in high and low through the median. Simple logistic regression models were set for adherence to infection control and independent variables, estimating the crude odds ratios with the respective 95% confidence intervals. The variables with p < 0.20 in the individual analyses were tested in multiple logistic regression models, remaining in the final model the variables with p ≤ 0.05.

RESULTS:

Individual and adjusted association analysis showed that female dentists have 1.41 ([95% CI: 1.08-1.84)] more adherence odds to infection control when compared with males (p < 0.05). There was no significant association in regarding age, time of education in dentistry, an undergraduate degree from a public or private school, and work in public and/or private clinics. There were also no differences among radiologists and dentists of other clinical specialties. The students from the last year of the dental schools had 1.7 [95% CI (1.13-2.57)] more chances of less adherence to infection control (p = 0.0001). There was no significant association with respect to sex, age and public or private schools.

CONCLUSIONS:

Educational procedures should be conducted in relation to infection control protocols in oral radiology, especially among male dentists, regardless clinic specialty, and among the students of the last year of the dental school.

Dynamics of the seasonal airborne propagation of Staphylococcus aureus in academic dental clinics

Objective

Staphylococcus aureus strains can be disseminated during dental treatments and occasionally lead to the contamination and infection of patients and dentists, which is an important public health problem. The dynamics of the airborne propagation and the genetic diversity of S. aureus isolated in an academic dental clinic environment were investigated using isoenzyme typing.

Material and Methods

The isoenzymes of 44 previously reported isolates were obtained from fresh cultures and extracted using glass beads. Nine isoenzymes were investigated using multilocus enzyme electrophoresis (MLEE). The genetic diversity and relationship among the strains (electrophoretic type – ET) were determined using statistics previously described by Nei²⁵ (1972) and the SAHN grouping method (UPGMA algorithm).

Results

Clonal pattern analyses indicated a high level of genetic polymorphism occurring among the 33 ETs, which were grouped into five taxa. Each taxon presented one or more clusters that were moderately related and that contained two or more identical/highly related isolates, revealing seasonal airborne propagation in these dental clinic environments.

Conclusions

These data suggest the occurrence of active microevolutionary processes in S. aureus as well as the possibility of environmental propagation during a 14-month time span. Such findings are important to show that multiuser academic dental clinics can retain certain strains that are spreadable to different niches.

Biofilm formation by Staphylococcus aureus isolates from a dental clinic in Konya, Turkey

The ability of Staphylococcus aureus to form biofilm is considered to be a major virulence factor influencing its survival and persistence in both the environment and the host. Biofilm formation in S. aureus is most frequently associated with production of polysaccharide intercellular adhesion by ica operon-encoded enzymes. The present work aimed at evaluating the in vitro biofilm production and presence of the icaA and icaD genes in S. aureus isolates from a dental clinic in Konya, Turkey. The surfaces of inanimate objects were sampled over a period of six months. S. aureus isolates were subjected to Congo Red Agar (CRA) and crystal violet (CV) staining assays to evaluate their ability of biofilm production, while the presence of the icaA and icaD genes was determined by polymerase chain reaction. S. aureus contamination was detected in 13.2% of the environmental samples. All the 32 isolates were observed to be positive for both the icaA and icaD genes. Phenotypic evaluations revealed that CV staining assay is a more reliable alternative to CRA assay to determine biofilm formation ability. A high percentage of agreement (91%) was observed between the results from CV staining and ica genes' detection assays. Phenotypic and genotypic evaluations should be combined to detect biofilm formation in S. aureus. Our findings indicate that dental clinic environments should be considered as potential reservoir for biofilm-producing S. aureus and thus cross contamination.

Risk of Methicillin-Resistant Staphylococcus aureus Transmission in the Dental Healthcare Setting: A Narrative Review

Objective.

Information on the risk of methicillin-resistant Staphylococcus aureus (MRSA) infection transmission in dental healthcare settings was incomplete only few years ago; therefore, MRSA infection control guidelines were necessarily based on data extrapolated from other fields. Recently, publication of specific studies have made it possible to review such risk.

Methods.

Studies of MRSA infection in dentistry were searched for using EMBASE, MEDLINE, and Google and were allocated into the following sections: (1) direct evidence: documented cases of MRSA transmission in dentistry; (2) indirect evidence: carriage rates among dental healthcare providers (DHCPs) and patients (high carriage rates suggest that transmission is likely); (3) speculative evidence: MRSA occurrence in the dental environment (high environmental contamination probably increases the risk of infection); and (4) speculative evidence: MRSA carriage in human dental plaque and saliva (oral carriers may spread MRSA in the environment during dental therapy, with consequent environmental contamination and probable increased risk of infection).

Results.

Our findings were as follows. First, transmission has been ascertained during surgical interventions, particularly in surgical units and among head and neck cancer patients. Second, carriage rates among DHCPs were lower than those among other healthcare workers. Carriage rates among adult patients were low, whereas among pedodontic and special care patients rates were higher than those in the general population. Third, MRSA has been detected in the environment of emergency and surgical units and in dental hospitals. Some individuals in poor general condition were oral MRSA carriers.

Conclusions.

The occupational risk of MRSA infection among DHCPs is minimal. Among special patients (eg, special care, hospitalized and cancer patients) the risk of infection is high, whereas among the remaining patients undergoing conventional therapy such risk is probably low.

Healthcare-associated viral and bacterial infections in dentistry

Infection prevention in dentistry is an important topic that has gained more interest in recent years and guidelines for the prevention of cross-transmission are common practice in many countries. However, little is known about the real risks of cross-transmission, specifically in the dental healthcare setting. This paper evaluated the literature to determine the risk of cross-transmission and infection of viruses and bacteria that are of particular relevance in the dental practice environment. Facts from the literature on HSV, VZV, HIV, Hepatitis B, C and D viruses, Mycobacterium spp., Pseudomonas spp., Legionella spp. and multi-resistant bacteria are presented. There is evidence that Hepatitis B virus is a real threat for cross-infection in dentistry. Data for the transmission of, and infection with, other viruses or bacteria in dental practice are scarce. However, a number of cases are probably not acknowledged by patients, healthcare workers and authorities. Furthermore, cross-transmission in dentistry is under-reported in the literature. For the above reasons, the real risks of cross-transmission are likely to be higher. There is therefore a need for prospective longitudinal research in this area, to determine the real risks of cross-infection in dentistry. This will assist the adoption of effective hygiene procedures in dental practice.

Nuclease modulates biofilm formation in community-associated methicillin-resistant Staphylococcus aureus

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging contributor to biofilm-related infections. We recently reported that strains lacking sigma factor B (sigB) in the USA300 lineage of CA-MRSA are unable to develop a biofilm. Interestingly, when spent media from a USA300 sigB mutant was incubated with other S. aureus strains, biofilm formation was inhibited. Following fractionation and mass spectrometry analysis, the major anti-biofilm factor identified in the spent media was secreted thermonuclease (Nuc). Considering reports that extracellular DNA (eDNA) is an important component of the biofilm matrix, we investigated the regulation and role of Nuc in USA300. The expression of the nuc gene was increased in a sigB mutant, repressed by glucose supplementation, and was unaffected by the agr quorum-sensing system. A FRET assay for Nuc activity was developed and confirmed the regulatory results. A USA300 nuc mutant was constructed and displayed an enhanced biofilm-forming capacity, and the nuc mutant also accumulated more high molecular weight eDNA than the WT and regulatory mutant strains. Inactivation of nuc in the USA300 sigB mutant background partially repaired the sigB biofilm-negative phenotype, suggesting that nuc expression contributes to the inability of the mutant to form biofilm. To test the generality of the nuc mutant biofilm phenotypes, the mutation was introduced into other S. aureus genetic backgrounds and similar increases in biofilm formation were observed. Finally, using multiple S. aureus strains and regulatory mutants, an inverse correlation between Nuc activity and biofilm formation was demonstrated. Altogether, our findings confirm the important role for eDNA in the S. aureus biofilm matrix and indicates Nuc is a regulator of biofilm formation.

Coming to a practice near you? Community-acquired meticillin resistant Staphylococcus aureus (CA-MRSA)

Hospital-acquired meticillin resistant Staphylococcus aureus (HA-MRSA) arose in the 1960s, but the last decade saw the emergence of a new entity: community-acquired MRSA (CA-MRSA). Unlike HA-MRSA, patients affected by CA-MRSA have no obvious risk factors and may present with recurrent skin and soft tissue infections (SSTI) or, rarely, severe necrotizing pneumonia. This article provides an overview of CA-MRSA and reinforces the standard infection control procedures required to prevent further spread.

CLINICAL RELEVANCE

The dental team require an awareness of emerging infections, their relevance to dentistry and the infection control procedures necessary to prevent transmission.

Are computer keyboards a cross-infection risk in a dental clinic?

Computers in dental surgeries located within the patient treatment room could potentially pose a risk of cross-infection of patients and operators. The aims of this investigation were to determine the degree of contamination of computer keyboards located in clinics and study rooms in a teaching dental hospital, to determine the survival time of micro-organisms on keyboards and to compare the efficiency of two common disinfectants in disinfecting keyboards. All keyboards were found to be contaminated with a variety of micro-organisms including Staphylococcus aureus, coagulasenegative staphylococci, Gram-negative rods and cocci. A range of Gram-positive and -negative bacteria and Candida albicans were able to survive up to 10 days in dried suspensions on computer keys. Seventy per cent isopropanol wipes proved effective in reducing the numbers of viable test organisms on keys by at least 96% and reducing contamination of keyboards in routine use. The data suggest that computers in dental study areas and clinics act as reservoirs of potentially pathogenic organisms including S. aureus and should be regularly disinfected to reduce the risk of cross-infection.