The commensal yeasts Candida spp. Are part of the normal microbiota found at different sites on the body including the oral cavity. Under certain conditions they can become pathogenic resulting in ‘oral candidiasis’. Candida albicans is the most commonly implicated species but other species (Candida parapsilosis, Candida metapsilosis, Candida tropicalis, Candida khmerensis , Candida glabrata, Candida dubliniensis ) may be involved. Studies have suggested that probiotics may be a useful preventive and therapeutic strategy for oral candidiasis.
The aim of this review was to investigate the efficacy of probiotics on oral Candida spp. counts.
Methods
Searches were conducted in the Embase, Medline/PubMed, Cochrane Central, clinicaltrials.gov databases, and other individual journals sources (Brazilian Dental Journal, Indian Journal of Health Sciences, and Biomedical Research Kleu) with no restrictions on language. Randomised controlled trials (RCTs) or pre-post intervention studies were considered. Two reviewers independently selected studies and extracted data. Risk of bias was assessed using the Cochrane domains-based tool for RCTs and the United States National Heart, Lung, and Blood Institute assessment tool for pre-post studies. Odds ratios (OR) were calculated for each study and a Bayesian random-effects meta-analysis model was used.
Results
- 12 studies (8 RCTs, 4 pre-post studies) involving a total of 843 patients were included.
- Sample sizes ranged from 21-192.
- Studies were conducted in 10 countries Brazil, China, Denmark, Finland, India, Italy, New Zealand,
- A total of 16 strains of probiotic (alone or in combination) were investigated.
- Most probiotics were delivered though lozenges or capsules, or with dairy products such as cheese, milk or yoghurt.
- Follow up periods ranged from 4 to 16 weeks.
- None of the RCTs was at low risk of bias for all domains with 3 have domains at high risk. One of the pre-post-studies was considered to be poor, the other 3 fair.
- Meta-analyses of all 12 studies suggested a 30% reduction in oral candidiasis with probiotic use although this was not significant; OR = 0.71 (95%CrI; 0.37 – 1.32).
- Meta-analysis of the 8 RCTs only did demonstrate a statistically significant benefit in favour of probiotic use; OR = 0.53 (95%CrI; 0.27 – 0.93).
- In a sensitivity analysis of RCTs comparing denture wearers and non-denture wearers a larger treatment effect in favour of probiotic was seen for denture wearers OR = 0.19 (95%CrI; 0.03 – 1.29) than for non-denture wearers OR= 0.65 (95%CrI; 0.36 – 1.17) although neither a statistically significant.
Conclusions
The authors concluded: –
despite the high heterogeneity among studies, we are confident in declaring that the treatment can have a beneficial effect on reducing oral Candida spp. counts.
Comments
A number of major databases and a small selection of journals was searched for this review. Of the 12 included studies 1 was conducted in children and only 3 involved denture wearers. There was variation in the both the probiotics tested as well as the dosage and delivery mechanism. A number of the studies also used healthy volunteers and the main outcome was change in the number of colony forming units.
Only the overall meta-analysis of the 8 RCTs demonstrated a statistically significant benefit in favour of probiotic use with the other analyses not achieving significance. There are also some concerns about the quality of the available studies. So while the findings suggest that probiotics may be useful additional high-quality well-reported trials are needed to address issues such a delivery mechanisms, dosage, duration and choice of probiotic stains as well as confirming their effectiveness.
Links
Primary Paper
Mundula T, Ricci F, Barbetta B, Baccini M, Amedei A. Effect of Probiotics on Oral Candidiasis: A Systematic Review and Meta-Analysis. Nutrients. 2019;11(10):2449. Published 2019 Oct 14. doi:10.3390/nu11102449
Other references
Dental Elf – 18th Feb 2020
Dental Elf – 28th Nov 2016
Picture Credits
“Candida albicans on Columbia Horse Blood Agar.” by Nathan Reading is licensed under CC BY-NC-ND 2.0
