Beneficial Microbes, 2014 September online 2014; 5(3): 1-8
ARTICLE IN PRESS
Wageningen Academic P u b l i s h e r s
Inhibitory activity in vitro of probiotic lactobacilli against oral Candida under different fermentation conditions Q. Jiang1, I. Stamatova1,2, K. Kari1 and J.H. Meurman1,3* 1Institute
of Dentistry, University of Helsinki, P.O. Box 41, 00014 Helsinki, Finland; 2Faculty of Dental Medicine, Medical University of Plovdiv, 26 Vasil Aprilov, 4000 Plovdiv, Bulgaria; 3Institute of Dentistry, University of Helsinki, Department of Oral and Maxillofacial Diseases, Helsinki University Central Hospital, P.O. Box 263, 00029 Hus, Helsinki, Finland; [email protected] Received: 6 May 2014 / Accepted: 31 July 2014 © 2014 Wageningen Academic Publishers
RESEARCH ARTICLE Abstract Clinical studies have shown that probiotics positively affect oral health by decreasing gum bleeding and/or reducing salivary counts of certain oral pathogens. Our aim was to investigate the inhibitory effect of six probiotic lactobacilli against opportunistic oral Candida species. Sugar utilisation by both lactobacilli and Candida was also assessed. Agar overlay assay was utilised to study growth inhibition of Candida albicans, Candida glabrata and Candida krusei by Lactobacillus rhamnosus GG, Lactobacillus casei Shirota, Lactobacillus reuteri SD2112, Lactobacillus brevis CD2, Lactobacillus bulgaricus LB86 and L. bulgaricus LB Lact. The inhibitory effect was measured at pH 5.5, 6.4, and 7.2, respectively, and in the presence of five different carbohydrates in growth medium (glucose, fructose, lactose, sucrose, and sorbitol). Growth and final pH values were measured at two-hour time points to 24 h. L. rhamnosus GG showed the strongest inhibitory activity in fructose and glucose medium against C. albicans, followed by L. casei Shirota, L. reuteri SD2112 and L. brevis CD2. None of the lactobacilli tested affected the growth of C. krusei. Only L. rhamnosus GG produced slight inhibitory effect on C. glabrata. The lower pH values led to larger inhibition zones. Sugar fermentation profiles varied between the strains. L. casei Shirota grew in the presence of all sugars tested, whereas L. brevis CD2 could utilise only glucose and fructose. All Candida species metabolised the available sugars but the most rapid growth was observed with C. glabrata. The results suggest that commercially available probiotics differ in their inhibitory activity and carbohydrate utilisation; the above properties are modified by different pH values and sugars with more pronounced inhibition at lower pH. Keywords: Lactobacillus, yeast, inhibition, sugar metabolism
1. Introduction The growing number of pathogens resistant to conventional antimicrobial therapies continues to impose global health risks worldwide. Infections caused by resistant microorganisms often fail to respond to the standard treatment, resulting in prolonged illness and greater risk of death. Antifungal resistance is a major concern when treating certain infectious diseases also in the oral cavity. Candida species are the most common fungal pathogens isolated from the human mouth (Scully et al., 1994). Many of them exist as commensals but in the immunocompromised host they can acquire invasive and pathogenic
properties leading to various clinical manifestations, ranging from superficial mucous membrane infections to life-threatening systemic diseases (Seneviratne et al., 2008). Candida albicans is the predominantly isolated species, followed by Candida tropicalis, Candida glabrata, Candida parapsilosis and Candida krusei (Scully, 2013). The incidence of Candida infections and the occurrence of C. albicans in the mouth of healthy young adults have increased after the advent of antibiotic therapy (Young et al., 1956). The non-albicans Candida (NAC) species, a heterogeneous group of organisms which differ from each other and from C. albicans (Moran et al., 2002), have also been increasingly detected in patients with
ISSN 1876-2833 print, ISSN 1876-2891 online, DOI 10.3920/BM2014.00541
ARTICLE IN PRESS
Wageningen Academic P u b l i s h e r s
Inhibitory activity in vitro of probiotic lactobacilli against oral Candida under different fermentation conditions Q. Jiang1, I. Stamatova1,2, K. Kari1 and J.H. Meurman1,3* 1Institute
of Dentistry, University of Helsinki, P.O. Box 41, 00014 Helsinki, Finland; 2Faculty of Dental Medicine, Medical University of Plovdiv, 26 Vasil Aprilov, 4000 Plovdiv, Bulgaria; 3Institute of Dentistry, University of Helsinki, Department of Oral and Maxillofacial Diseases, Helsinki University Central Hospital, P.O. Box 263, 00029 Hus, Helsinki, Finland; [email protected] Received: 6 May 2014 / Accepted: 31 July 2014 © 2014 Wageningen Academic Publishers
RESEARCH ARTICLE Abstract Clinical studies have shown that probiotics positively affect oral health by decreasing gum bleeding and/or reducing salivary counts of certain oral pathogens. Our aim was to investigate the inhibitory effect of six probiotic lactobacilli against opportunistic oral Candida species. Sugar utilisation by both lactobacilli and Candida was also assessed. Agar overlay assay was utilised to study growth inhibition of Candida albicans, Candida glabrata and Candida krusei by Lactobacillus rhamnosus GG, Lactobacillus casei Shirota, Lactobacillus reuteri SD2112, Lactobacillus brevis CD2, Lactobacillus bulgaricus LB86 and L. bulgaricus LB Lact. The inhibitory effect was measured at pH 5.5, 6.4, and 7.2, respectively, and in the presence of five different carbohydrates in growth medium (glucose, fructose, lactose, sucrose, and sorbitol). Growth and final pH values were measured at two-hour time points to 24 h. L. rhamnosus GG showed the strongest inhibitory activity in fructose and glucose medium against C. albicans, followed by L. casei Shirota, L. reuteri SD2112 and L. brevis CD2. None of the lactobacilli tested affected the growth of C. krusei. Only L. rhamnosus GG produced slight inhibitory effect on C. glabrata. The lower pH values led to larger inhibition zones. Sugar fermentation profiles varied between the strains. L. casei Shirota grew in the presence of all sugars tested, whereas L. brevis CD2 could utilise only glucose and fructose. All Candida species metabolised the available sugars but the most rapid growth was observed with C. glabrata. The results suggest that commercially available probiotics differ in their inhibitory activity and carbohydrate utilisation; the above properties are modified by different pH values and sugars with more pronounced inhibition at lower pH. Keywords: Lactobacillus, yeast, inhibition, sugar metabolism
1. Introduction The growing number of pathogens resistant to conventional antimicrobial therapies continues to impose global health risks worldwide. Infections caused by resistant microorganisms often fail to respond to the standard treatment, resulting in prolonged illness and greater risk of death. Antifungal resistance is a major concern when treating certain infectious diseases also in the oral cavity. Candida species are the most common fungal pathogens isolated from the human mouth (Scully et al., 1994). Many of them exist as commensals but in the immunocompromised host they can acquire invasive and pathogenic
properties leading to various clinical manifestations, ranging from superficial mucous membrane infections to life-threatening systemic diseases (Seneviratne et al., 2008). Candida albicans is the predominantly isolated species, followed by Candida tropicalis, Candida glabrata, Candida parapsilosis and Candida krusei (Scully, 2013). The incidence of Candida infections and the occurrence of C. albicans in the mouth of healthy young adults have increased after the advent of antibiotic therapy (Young et al., 1956). The non-albicans Candida (NAC) species, a heterogeneous group of organisms which differ from each other and from C. albicans (Moran et al., 2002), have also been increasingly detected in patients with
ISSN 1876-2833 print, ISSN 1876-2891 online, DOI 10.3920/BM2014.00541
