key: cord-0894873-2b97ywkp
authors: Karimzadeh, Fazel; Sajedi, Seyed Masoud; Taram, Saman; Karimzadeh, Fathemeh
title: Increased bacterial colonization on removable dental prostheses in patients with Covid-19
date: 2021-05-21
journal: J Prosthet Dent
DOI: 10.1016/j.prosdent.2021.04.020
sha: 0cf90512aa67a4ac982ce45158d7b3c8ce4bac8c
doc_id: 894873
cord_uid: 2b97ywkp

Statement of problem In the outbreak of Covid-19, coinfections and even superinfections in the background of SARS-CoV-2 viral infection have been reported. Such bacterial and fungal strains may be colonized in different tissues and organs, including the oral cavity. Whether infection with Covid-19 could increase colonization of different bacterial strains on removable dental prostheses is unclear. Purpose The purpose of this clinical study was to compare bacterial colonization on removable dental prostheses in patients with Covid-19. Material and methods Two sex- and age-matched groups of complete-denture wearing participants (N=60) with and without a positive diagnosis for Covid-19 were enrolled in the study. Swabs were used at 2 different time intervals to sample areas of the dentures, which were then cultured and the colony smears Gram stained. Statistical analysis was conducted by using the Mann U Whitney test (α=.05). Results Streptococcus species (93.3% versus 40.0%, P=.047) and Klebsiella pneumonia (46.7% versus 13.4%, P=.036) were detected more frequently in the Covid-19 positive group. Conclusions Higher rates of bacterial colonization, especially with Streptococcus species and Klebsiella pneumonia, were detected on removable dental prostheses after Covid-19 infection.

Removable dentures are still popular, especially in economically disadvantaged communities because of their cost-effectiveness. However, denture wearing can gradually alter the oral ecology, especially oral microorganisms, and may provide the conditions for the invasion and colonization of pathogenic microorganisms. 1 The emergence of such conditions for oral and dental microorganisms and microflora can result in denture-related lesions such as denture stomatitis. 2 J o u r n a l P r e -p r o o f With the advent the Covid-19 pandemic, many concerns about the consequences of this viral disease have been identified, including its potential oral and dental complications. 3, 4 Oral manifestations of this infection include palate stomatitis and ulcers, halitosis with generalized erythematous and edematous gingivae, and necrotic interdental papillae with unprovoked gingival bleeding. 5, 6 Additionally Covid-19 infection may have a detrimental effect on denture wearers, creating conditions for further colonization of opportunistic bacteria and changes in the oral microflora. 7 However studies that evaluated such detrimental effects are sparse. The present study assessed microbial contamination of removable dental prostheses in adults diagnosed with Covid-19 and then compared this condition with a similar time period in the year before the occurrence of the Covid-19 pandemic. The null hypothesis was that denture wearers with Covid-19 are not prone to other microbial infections.

In this pilot study, 2 sex-and age-matched groups of denture wearers at 2 different time intervals were enrolled in the study (N=60). The sample size provided a statistical power of 80% and a confidence interval of 95%. The first group (n=30) was recruited from patients referred to the Yasoj Dental clinic between January and April 2019 for their first removable complete dentures.

The routine protocol in this clinic has been swab sampling to evaluate bacterial microorganisms on the intaglio surface of the prosthesis 6 months after prosthesis placement. Therefore, participants with complete information about their bacterial evaluation were included in the study. Patients with systemic disorders or severe infections requiring antibiotic therapy were excluded from the study. The second group (n=30) were recruited from patients who received removable complete dentures between and January and April 2020 and had been diagnosed with J o u r n a l P r e -p r o o f Covid-19 disease. These diagnoses were made following tracing 3 months subsequent to the emergence of clinical manifestations associated with Covid-19 disease followed by molecular evaluation for the SARS-CoV-2 virus. Patients with evidence of severe disease, the need for hospitalization, evident lung involvement on computed tomography (CT) scan, or the need for antibiotics were excluded from the study. These participants had also received swab sampling of the denture surface within 3 months of the diagnosis of Covid-19. Individuals in either group receiving specific medications or reporting subjective symptoms of systemic or oral diseases were excluded.

To collect samples from the denture surface, a sterile cotton swab impregnated with phosphate buffer salt (PBS) was rubbed on the intaglio surface and then inserted in the tube containing PBS and transferred immediately to a microbiology laboratory. All assessments were done in a single laboratory in contract with the clinic. After shaking, the collected swab was inoculated onto the MacConkey agar and blood agar plates with a sterile pipette. The plates were then incubated for 48 hours at 37 °C and assessed for microbial growth, and the colony smears were prepared and Gram stained. The strains of microorganisms were identified by using specific biochemical tests and counted by a calibrated microbiologist (F.K) using a colony counter (Sterlitech, Spatz).

The results were presented as mean ±standard deviation (SD) for quantitative variables and were summarized by absolute frequencies and percentages for categorical variables. Table 1 

The present study determined that patients with COVID-19 infection were significantly more prone to other microbial colonization, so the null hypothesis was rejected. Co-infections and even superinfections have been reported to be associated with SARS-CoV-2 viral infection. 8, 9 Several bacterial pathogens appear to be prevalent as causative agents of secondary infections, including antibiotic-resistant strains of Staphylococcus aureus and Klebsiella pneumonia. 10 complications. Evidence suggests that periodontal pathogenic bacteria are involved in the pathogenesis of respiratory diseases, such as those implicated in COVID-19. 14 The present study had limitations such as the small sample size and short follow-up time.

Future studies should evaluate the same study concept with a higher sample size and longer follow-up time with more strict inclusion criteria.

Based on the findings of this clinical study, the following conclusions were drawn:

1. Patients with Covid-19 may experience increased bacterial colonization on dentures, even in its early and mild stages. J o u r n a l P r e -p r o o f 

Colonization of dental plaque by respiratory pathogens in dependent elderly

Oral mucosal lesions associated with the wearing of removable dentures

Novel coronavirus (COVID-19) and dentistry-a comprehensive review of literature

Immunocompromised patients and coronavirus disease 2019: a review and recommendations for dental health care

COVID-19-related oral manifestations: early disease features?

Oral vesiculobullous lesions associated with SARS-CoV-2 infection

COVID-19 and community dental services: The challenges ahead

Evaluation of bacterial co-infections of the respiratory tract in COVID-19 patients admitted to ICU

Etiology and antimicrobial resistance of secondary bacterial infections in patients hospitalized with COVID-19 in Wuhan, China: a retrospective analysis

Intervention strategies for an influenza pandemic taking into account secondary bacterial infections

Co-infections in people with COVID-19: a systematic review and meta-analysis

Bacterial co-infection and secondary infection in patients with COVID-19: a living rapid review and metaanalysis

Oral mucosal lesions in a COVID-19 patient: New signs or secondary manifestations?

Metagenome of SARS-Cov2 patients in Shenzhen with travel to Wuhan shows a wide range of