Bacterial contamination on used face masks among nursing home healthcare personnel

The bacterial burden of worn face masks-observational research and literature review

Introduction

Facemasks were widely mandated during the recent SARS-CoV-2 pandemic. Especially the use by the general population is associated with a higher risk of improper handling of the mask and contamination and potential adverse microbiological consequences.

Methods

We investigated and quantified bacterial accumulation in facemasks used by the general population, using 16S rRNA (Sanger Sequencing), culture and biochemical analysis along with Rose Bengal staining. Additionally, a systematic overview of the literature on face mask contamination was undertaken.

Results

We found an average bacterial load of 4.24 × 104 CFU recovered/mask, with a maximum load of 2.85 × 105 CFU. This maximum is 310 times higher than the limit value for contamination of ventilation system outlet surfaces specified by the German standard VDI 6022. Biochemical and molecular identification predominantly found Staphylococcus species (80%), including Staphylococcus aureus, along with endospore-forming Bacillus spp. Literature reports also indicate contamination of masks by bacterial and fungal opportunists of the genera Acinetobacter, Aspergillus, Alternaria, Bacillus, Cadosporium, Candida, Escherichia, Enterobacter, Enterococcus, Klebsiella (including K. pneumoniae), Micrococcus, Microsporum, Mucor, Pseudomonas, Staphylococcus and Streptococcus. Bacterial counts increase linearly with wearing duration.

Discussion

Prolonged use may affect the skin and respiratory microbiomes, promoting consequential eye, skin, oral and airway conditions. These aspects underscore the urgent need for further research and a risk-benefit analysis in respect of mask use, particularly given their unproven efficacy in disrupting the transmission of respiratory viruses and their adverse social consequences.

Contamination of Dental Surgical Masks by Aerosols Generated During Different Dental Treatments

PURPOSE

The COVID-19 pandemic raised the question about the extent of microbial exposure encountered by dentists during dental therapy. The purpose of this study was to quantify microbial counts on surgical masks related to duration and type of dental therapy, as well as patient oral health variables.

MATERIALS AND METHODS

Sterile filter papers were fixed on surgical masks used during routine daily dental therapy. Thereafter, the filter papers were pressed onto blood agar plates for 1 min, before the agar plates were incubated with 10% CO2. After 48 h, the colony forming units (CFU) were counted and microorganisms were identified. The dependence of the CFU counts on treatment and patient-related variables was analysed using linear regression.

RESULTS

Filter papers obtained from 322 dental treatments (429 masks) were included in the final analysis. On average, 5.41 ± 9.94 CFUs were counted. While mostly oral bacteria were detected, Staphylococcus aureus was also identified on 16 masks. Linear regression, incorporating patient-related and treatment characteristics through step-wise inclusion, revealed statistical significance (p 0.001) only with the variable 'assistance during therapy'. The type of dental treatment exhibited a trend, with fewer CFUs observed in caries treatment compared to periodontal or prosthodontic therapy. Furthermore, after analysing filter papers from masks used by dental assistants in 107 dental treatments, fewer CFUs were found on the masks compared to those used by dentists (p 0.001).

CONCLUSION

The mean number of CFUs observed consistently remained low, highlighting the efficacy of the implemented hygiene measures. Consequently, it is clinically recommended to support dental treatment with precise suction of the generated aerosols.

Comparative Evaluation of Microbial Contamination on the Mobile Phones Used by Dental Health-care Professionals versus Faculty of School System

Introduction

Mobile phones are frequently used in environments of high bacteria presence. These can harbor various potential pathogens and become an exogenous source of nosocomial infections. Even in recent outbreak of COVID-19, it has become a point which needs to be sanitized to prevent and control further disease transmission as it is equally important for health-care professionals to use mobile phones in the hospital and other health and care settings, especially for communication. The present study was conducted to determine the potential role of mobile phones in the dissemination of disease.

Objective

To compare the evaluation of microbial contamination on the mobile phones used by dental health-care professionals and faculty of senior secondary school and to access the microbial contamination of mobile phones by measuring the percentages of pathogens and to determine the type of bacteria commonly present on mobile phones. It also assesses the efficacy of 70% ethyl alcohol to be used as decontamination solution.

Materials and Methods

A total of 126 mobile phones were screened in the study; 63 mobile phones belonging to dental health-care personnel from nine different specialties of dental college (Group 1 - test group) and 63 mobile phones belonging to nonhealth-care personnel like school teachers of senior schools (Group 2 - control group). All the samples were taken before and after cleaning with 70% ethyl alcohol. A total of 252 swab samples were taken.

Results

Microbial contamination was approximately 68% in swab samples taken from mobile phones before cleaning with 70% of ethyl alcohol but even with one time disinfection with alcohol, decontamination was found to be only 95% effective. Coagulase-negative Staphylococcus was the most common isolated organism in swabs collected from dental college. Pathogenic bacteria were more prevalent in samples of dental college than to school samples.

Conclusion

Ninetythree percentage of cell phones of health-care workers were contaminated and they act as potential source of nosocomial infections. Alcohol should be used to disinfect the mobile phones.