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Abstract Background Elucidation of the communal behavior of microbes in mixed species biofilms may have a major impact on understanding infectious diseases and for the therapeutics. Although, the structure and the properties of monospecies biofilms and their role in disease have been extensively studied during the last decade, the interactions within mixed biofilms consisting of bacteria and fungi such as Candida spp. have not been illustrated in depth. Hence, the aim of this study was to evaluate the interspecies interactions of Pseudomonas aeruginosa and six different species of Candida comprising C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis, and C. dubliniensis in dual species biofilm development. Results A significant reduction in colony forming units (CFU) of C. parapsilosis (90 min), C. albicans and C. tropicalis (90 min, 24 h and 48 h), C. dubliniensis and C. glabrata, (24 h and 48 h) was noted when co-cultured with P. aeruginosa in comparison to their monospecies counterparts (P < 0.05). A simultaneous significant reduction in P. aeruginosa numbers grown with C. albicans (90 min and 48 h), C. krusei (90 min, 24 h and 48 h),C. glabrata, (24 h and 48 h), and an elevation of P. aeruginosa numbers co-cultured with C. tropicalis (48 h) was noted (P < 0.05). When data from all Candida spp. and P. aeruginosa were pooled, highly significant mutual inhibition of biofilm formation was noted (Candida P < 0.001, P. aeruginosa P < 0.01). Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) analyses confirmed scanty architecture in dual species biofilm in spite of dense colonization in monospecies counterparts. Conclusions P. aeruginosa and Candida in a dual species environment mutually suppress biofilm development, both quantitatively and qualitatively. These findings provide a foundation to clarify the molecular basis of bacterial-fungal interactions, and to understand the pathobiology of mixed bacterial-fungal infections.

Most viral infections encountered in resource-rich countries are relatively trivial and transient with perhaps fever, malaise, myalgia, rash (exanthema) and sometimes mucosal manifestations (enanthema), including oral in some. However, the apparent benignity may be illusory as some viral infections have unexpected consequences - such as the oncogenicity of some herpesviruses and human papillomaviruses. Infections are transmitted from various human or animal vectors, especially by close proximity, and the increasing movements of peoples across the globe, mean that infections hitherto confined largely to the tropics now appear worldwide. Global warming also increases the range of movement of vectors such as mosquitoes. Thus recent decades have seen a most dramatic change with the emergence globally also of new viral infections - notably human immunodeficiency viruses ( HIV) - and the appearance of some other dangerous and sometimes lethal infections formerly seen mainly in, and reported from, resource-poor areas especially in parts of Asia, Latin America and Africa. This study offers a brief update of the most salient new aspects of the important viral infections, especially those with known orofacial manifestations or other implications for oral health care. [ABSTRACT FROM AUTHOR]

AIM: To investigate prospectively the qualitative and quantitative changes in oral carriage of yeasts and coliforms in southern Chinese people suffering from stroke. MATERIALS AND METHODS: In 56 elderly people suffering from stroke in a rehabilitation unit of a general medical hospital in Hong Kong, oral microbiological sampling using a combined imprint culture, oral rinse approach and clinical assessment was made during the acute stroke phase, on hospital discharge and 6 months later. RESULTS: The oral carriage of yeasts increased significantly during acute stroke (P<0.05), whereas coliform carriage did not. A reduction in oral carriage of yeasts was found on hospital discharge and 6 months later and in coliforms at the 6-month assessment (P<0.05). Candida albicans and Klebsiella pneumoniae were the predominant yeast and coliform respectively. Stroke-related difficulty in tooth brushing and denture wearing were associated with higher oral yeast carriage (P<0.05). We also report here for the first time that the use of aspirin was associated with lower oral yeast carriage in people suffering from stroke. CONCLUSION: Oral yeast carriage was closely linked to the level of stroke-related functional disability that improved over time but had not totally resolved 6 months after hospital discharge. The oral reservoir of yeasts and coliforms in people suffering from stroke is noteworthy by care providers as K. pneumoniae may cause aspiration pneumonia. [ABSTRACT FROM AUTHOR]

Objective: To investigate the expression of interleukin-1 α (IL-1 α), IL-1ra and IL-8 by the oral epithelium challenged by various Candida species. Materials and methods: In vitro candidiasis was induced by C. albicans wild type SC5314, its EFG1, CPH1 and secretory aspartyl proteinase ( SAP) mutants and, ATCC isolates of C. albicans, C. tropicalis and C. dubliniensis using a reconstituted human oral epithelium (RHOE) model. IL-1 α, IL-1ra and IL-8 levels in culture media were quantified by an enzyme-linked immunosorbent assay at 12, 24 and 48 h. Fungal invasion and IL-1ra expression in RHOE were detected by periodic acid-Schiff staining and immunohistochemistry. Results: Overall, the invasive Candida induced relatively higher levels of IL-1 α, IL-1ra and IL-8 in the culture media than the noninvasive isolates. IL-1 α and IL-1ra levels induced by Candida with hyphal invasion were significantly higher ( P < 0.05) than those induced by the isolates without hyphal invasion at 12, 24 and 48 h. Candida albicans SC5314 induced IL-1ra expression in RHOE at 12 and 24 h but not at 48 h consistent with its hyphal invasion; while the noninvasive mutants and non- albicans Candida induced IL-1ra expression at 48 h. Conclusions: The cytokine expression profiles in experimental oral candidiasis may be associated with the invasive potential of Candida. [ABSTRACT FROM AUTHOR]

Background: Oral candidiasis is a common problem in compromised patients. Although several non- albicans Candida species have emerged as pathogens the majority of candidal infections are caused by Candida albicans. Morphogenesis from the blastospore to filamentous phase, and production of secretory aspartyl proteinases (SAP) are two major virulence attributes of these opportunistic yeast. Histopathology of oral candidiasis is characterized by fungal invasion of the superficial epithelium although the invasive potentials of different Candida species vary. Computerized image analysis systems (IAS) utilizing immunohistochemistry have been successfully employed for quantification of such histopathological features. The purpose of this study was to evaluate quantitatively the in vitro invasive potential of C. albicans and its hyphal and SAP mutants, and five other non- albicans Candida species using a computerized IAS. Methods: In vitro human oral candidiasis was produced using five wild type and one reference C. albicans isolates, hyphal and SAP mutants of C. albicans SC 5314, and one wild type and one reference isolate each of C. tropicalis, C. dubliniensis, C. glabrata, C. parapsilosis and C. krusei in a reconstituted human oral epithelium (RHOE) model. The infected tissues were examined histologically at 12, 24 and 48 h. Invading fungal elements were visualized by periodic acid-Schiff (PAS) staining and quantitatively evaluated as a percentage of total tissue invasive area, using a computerized IAS. Results: All C. albicans isolates including hyphal mutant cph1/cph1 and SAP mutants; sap 1-3, sap 4-6 produced hyphae and differentially ( P < 0.05) invaded the tissue over 48 h. The invasive potential of hyphal mutant cph1/cph1 and SAP mutants ( sap 1-3, sap 4-6) were similar to the parent wild-type isolate at 12 h although after 24 h their invasion was dissimilar ( P < 0.05). Non- albicans Candida species and hyphal mutants; efg1/efg1, efg1/efg1 cph1/cph1 were all non-invasive. Conclusions: RHOE model in combination with computerized image analysis permits for the first time, the assessment of invasive potential of Candida species in a quantitative manner. The differential tissue invasive patterns of various C. albicans isolates, their mutants and other Candida species are also described. [ABSTRACT FROM AUTHOR]

Objective: The combination of amine fluoride and stannous fluoride (AmF/SnF2) was, by chance, found to be antifungal in a clinical trial. This study investigated its effect on pathogenic Candida species with the hypothesis that the antifungal action on different species is variable. Materials and methods: Growth inhibition effect of Meridol® mouth rinse which contains 250 ppm AmF/SnF2 was evaluated on 43 reference and clinical strains of Candida albicans, C. dubliniensis, C. glabrata, C. guilliermondii, C. krusei, C. parapsilosis, and C. tropicalis. Meridol® base solution without AmF/SnF2 was used as a negative control. Results: Undiluted Meridol® mouth rinse killed most study strains within a few minutes. In ascending order, C. parapsilosis, C. tropicalis, C. albicans, C. glabrata, C. krusei and C. dubliniensis showed higher resistance against AmF/SnF2 than C. guilliermondii. Conclusion: AmF/SnF2 could be used as a potent adjunct to antifungal therapy for oral yeasts. Although different Candida species demonstrated variable sensitivity the most prevalent oral yeast C. albicans appeared sensitive to the AmF/SnF2 combination. [ABSTRACT FROM AUTHOR]