Controlling cross-infection.
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Dentistry↗
Biomedical subjects
L P Samaranayake
Publications and source records attributed to L P Samaranayake.
The effect of antifungal agents on the in vitro susceptibility of Candida albicans to apo-lactoferrin.
The effect of subminimal inhibitory concentrations (MICs) of nystatin, amphotericin B, clotrimazole, miconazole and 5-fluorocytosine on the in vitro susceptibility of Candida albicans to physiological concentrations of apo-lactoferrin was investigated. Pre-exposure of C. albicans in 1:4 and 1:16 MICs of the antifungals resulted in an increased resistance to apo-lactoferrin-mediated cell death. Preincubation of Candida in tunicamycin (an agent that inhibits the synthesis of yeast cell-wall mannoproteins) and subsequent exposure to apo-lactoferrin enhanced the antifungal activity, whilst addition of ergosterol (a yeast cell-wall component) to the assay suspension had no significant effect. These results taken together indicate that apo-lactoferrin, an important component of saliva, interacts with cell-membrane constituents of C. albicans such as mannoproteins, and may modulate the effect of topical antifungal agents commonly prescribed for oral candidoses.
Amphotericin B↗
The oral prevalence of aerobic and facultatively anaerobic gram-negative rods and yeasts in Hong Kong Chinese.
Saline oral rinse samples were obtained from 300 community-dwelling Hong Kong Chinese attending an outpatient dental clinic to determine the oral prevalence of aerobic and facultatively anaerobic Gram-negative rods (AGNR) and yeasts. The oral prevalence of AGNR was 41.7%. Enterobacteriaceae species comprised 73% of all AGNR isolated, with an overall prevalence of 32%. There was no difference in prevalence between females (n = 190) and males (n = 110). Morning samples (n = 154) yielded a significantly higher prevalence of AGNR (54.5%) and Enterobacteriaceae (42.2%) than afternoon samples (n = 146) (28.1 and 21.2%, respectively; p < 0.01, p < 0.01). Subjects over 50 yr had a significantly higher prevalence of AGNR than those aged 30-49 yr (p < 0.01). The most commonly isolated AGNR species were Enterobacter cloacae and Klebsiella pneumoniae pneumoniae. The oral prevalence of yeasts was 24%, with Candida albicans forming 77% of all yeasts isolated. Subjects taking medication (n = 38) or wearing dentures (n = 38) had a significantly higher oral yeast prevalence of 36.8 (p < 0.05) and 44.7% (p < 0.01), respectively. Yeast prevalence was significantly higher in subjects over 50 yr than those aged 30-49 yr (p < 0.05) and 15-29 yr (p < 0.05). Comparisons with previous studies suggest that the oral prevalence of AGNR in Chinese may be higher in Hong Kong than in other parts of the world.
Adolescent↗
Anti-Candida activity of murine bronchoalveolar lavage fluid.
Respiratory secretions provide an efficient method for protecting the large surface area of the lower respiratory tract. To determine whether lung secretions contribute to antifungal defences, murine bronchoalveolar lavage fluid (BLF) was tested for anti-candidal activity against 49 oral and vaginal isolates belonging to six different Candida species. The yeasts were incubated in unconcentrated, cell-free lavage fluid from Sprague-Dawley rats and then cultured quantitatively to measure residual viability. Experiments with C. albicans indicated that sensitivity to BLF increased in a time- and dose-dependent manner. This activity was heat-stable (56 degrees C) and consistent, irrespective of whether the BLF was derived from rats inoculated (orally) with candida or the uninoculated controls. Of the Candida spp. examined, C. albicans was the most susceptible followed by C. parapsilosis and C. tropicalis, whereas C. krusei, C. guilliermondii and C. glabrata were highly resistant. However, there were differences in susceptibility to BLF among different isolates within a given species. These results indicate that a heat-stable, soluble factor(s) in murine lavage fluid may suppress candidal colonisation of the lower respiratory tract and contribute to the defence mechanisms of the lungs.
Animals↗
Adhesion and colonisation of Candida krusei on host surfaces.
Candida krusei is an emerging pathogen, especially in immunocompromised hosts. As the adherence of this organism both to host epithelial surfaces and to catheter and prosthetic surfaces appears to be important in the pathogenesis of superficial as well as systemic candidoses, the adhesion of 20 oral isolates of C. krusei and five oral isolates of C. albicans was compared with the following substrates: cultured (HeLa) epithelial cells, buccal epithelial cells (BEC) from healthy adults and bone marrow transplant patients, and acrylic (polymethylmethacrylate) surfaces. Animal experiments in Sprague Dawley rats were also conducted to evaluate the relative oral carriage rate of the two Candida spp. C. krusei isolates adhered in far greater numbers to acrylic surfaces than to either of the cell surfaces. Significant intra-species differences in C. krusei adhesion for acrylic surfaces were noted between 74 (39%) of 190 pair comparisons in contrast to 18 (9.5%) of 190 with HeLa surfaces (p < 0.05). A positive correlation was also observed between the adhesion of C. krusei isolates to HeLa cells and acrylic surfaces. Five isolates of C. albicans showed very low adherence to HeLa surfaces when compared with BEC obtained from either healthy individuals or bone marrow transplant patients. The adherence of C. albicans to BEC from the healthy individuals was c. 12-fold greater than that of C. krusei, a figure similar to the relative murine oral carriage rate of the two Candida spp.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Candida krusei: biology, epidemiology, pathogenicity and clinical manifestations of an emerging pathogen.
Early reports of Candida krusei in man describe the organism as a transient, infrequent isolate of minor clinical significance inhabiting the mucosal surfaces. More recently it has emerged as a notable pathogen with a spectrum of clinical manifestations such as fungaemia, endophthalmitis, arthritis and endocarditis, most of which usually occur in compromised patient groups in a nosocomial setting. The advent of human immunodeficiency virus infection and the widespread use of the newer triazole fluconazole to suppress fungal infections in these patients have contributed to a significant increase in C. krusei infection, particularly because of the high incidence of resistance of the yeast to this drug. Experimental studies have generally shown C. krusei to be less virulent than C. albicans in terms of its adherence to both epithelial and prosthetic surfaces, proteolytic potential and production of phospholipases. Furthermore, it would seem that C. krusei is significantly different from other medically important Candida spp. in its structural and metabolic features, and exhibits different behaviour patterns towards host defences, adding credence to the belief that it should be re-assigned taxonomically. An increased awareness of the pathogenic potential of this yeast coupled with the newer molecular biological approaches to its study may facilitate the continued exploration of the epidemiology and pathogenesis of C. krusei infections.
Animals↗
The in vitro proteolytic and saccharolytic activity of Candida species cultured in human saliva.
The proteolytic and saccharolytic activity of 4 Candida species was investigated in batch cultures of pooled, human mixed saliva supplemented with glucose. All the Candida species investigated (Candida albicans, Candida tropicalis, Candida glabrata and Candida krusei) demonstrated a marked growth in saliva with a concomitant reduction in pH from about 7.5 to 3.3, within 72 h. Isotachophoretic analysis of the culture supernatant revealed the presence of a variety of acid anions of which pyruvate and acetate were the most abundant. Proteolysis of salivary components, evaluated by a biochemical assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was exhibited by all 4 Candida species, although there was inter-species variation. Despite the similarity in growth rates, C. tropicalis and C. krusei demonstrated greater proteolytic activity than C. albicans and C. glabrata. Neither candidal growth nor proteolysis was observed in glucose-free control saliva samples. In contrast, the degree of saccharolytic and proteolytic activity of a single isolate of C. albicans in glucose-supplemented parotid saliva appeared to be relatively weak compared with mixed saliva. As the oral cavity provides ideal low pH niches periodically supplemented with dietary carbohydrates, the acidic proteinases of Candida species may play a role in the pathogenesis of oral candidiasis.
Analysis of Variance↗
The effect of indigenous bacterial populations on buccal epithelial cells on subsequent microbial adhesion in vitro.
Despite the numerous investigations on the adhesion of microorganisms to buccal epithelial cells, it is difficult to correlate different results, as disparate adherence values have been reported for a given organism. As one reason for this disparity may be the indigenous or natural bacterial populations on human buccal epithelial cells, the effect of the latter on subsequent microbial adherence in vitro was examined. There was a highly significant correlation between the degree of natural bacterial colonization on pooled buccal epithelial cells from 8 healthy donors and the adhesion of a single isolate each of Streptococcus mitis, Escherichia coli and Actinomyces naeslundii. However, no such relationship could be established for Candida albicans, Streptococcus milleri and another isolate of Streptococcus mitis. As in previous studies, variation in adherence values was found, both between samples from different donors, and from the same donor over time, but to a far lesser degree in pooled samples from different donors. These results imply that natural bacterial populations on buccal epithelial cells may affect the adhesion values derived from laboratory experimentation, and hence such data should be interpreted with caution.
Actinomyces↗
Candida-associated palatal papillary hyperplasia in HIV infection.
Oral Candida infections may appear in many guises, especially in HIV-infected individuals. Whereas the pseudomembranous and the erythematous forms of oral candidiasis are the most frequently encountered in such patients, there appear to be further clinical variants of this disease. This paper describes seven dentate homosexual AIDS patients who developed papillary hyperplasia of the palate which was associated with Candida infection. Such lesions, classically related to denture stomatitis, have rarely been described in dentate patients, and this report further expands the spectrum of candidal infections seen in HIV disease.
AIDS-Related Opportunistic Infections↗
Oral and oropharyngeal prevalence of Enterobacteriaceae in humans: a review.
Members of the Enterobacteriaceae family are widely distributed in nature and exhibit substantial diversity in ecology, host range and pathogenic potential for man. While wide discrepancies in methodology exist between epidemiological studies, the available data indicate an increased prevalence of oral and/or oropharyngeal Enterobacteriaceae carriage in patients with illnesses of varying severity compared with healthy subjects. This paper reviews the prevalence of Enterobacteriaceae in the oral and oropharyngeal region of healthy human subjects and those affected by different disease entities, and discusses the complexities associated with collating and interpreting such data. The effect of antimicrobials and antiseptics on oral and oropharyngeal Enterobacteriaceae has also been reviewed, while highlighting the gaps in knowledge and future research directions.
Adolescent↗
Candida and oral candidosis: a review.
Candida species are the most common fungal pathogens isolated from the oral cavity. Their oral existence both as a commensal and an opportunist pathogen has intrigued clinicians and scientists for many decades, and recent investigations have revealed many attributes of this fungus contributing to its pathogenicity. In addition, the advent of the human immunodeficiency virus infection and AIDS has resulted in a resurgence of oral Candida infections. Clinicians are witnessing not only classic forms of the diseases but also newer clinical variants such as erythematous candidosis, rarely described hithertofore. Therefore, this review is an attempt at detailing the current knowledge on Candida and oral candidoses together with the newer therapeutic regimes employed in treating these mycoses.
AIDS-Related Opportunistic Infections↗
Attitudes to cross-infection measures of UK and Hong Kong patients.
The knowledge and attitudes of dental patients in the UK and Hong Kong towards aspects of cross-infection control have been surveyed. Almost all patients expected dentists to wear protective gloves but only 73% and 40% expected dental staff to wear protective face masks and spectacles respectively. Most patients were aware that such measures were for the benefit of both dental staff and patients. Just over 50% of patients believed that they could contact HIV from an HIV-infected dentist. UK and Cantonese patients had generally similar attitudes to cross-infection protection, but the latter were positively influenced by the routine use of masks and spectacles and were more concerned about HIV transmission than UK patients.
Attitude to Health↗
'An assessment of the incidence of punctures in gloves when worn for routine operative procedures'.
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Dental Staff↗
'Perception of risk of HIV infection from regular attenders to an industrial dental service'.
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Dental Care↗
Revised guidelines for HIV-infected health care workers.
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Dentists↗
Interactions between denture lining material, protein pellicles and Candida albicans.
The interactions between pellicles derived from saliva, serum, mucin and lysozyme deposited on lining material (tissue conditioner) and Candida albicans were investigated by monitoring pH changes associated with protein-free and protein-coated lining material and by ultrastructural observations of yeast colonization. No significant differences in pH reduction between culture media in contact with the protein-free, control lining materials and those coated with saliva, serum or mucin were observed after 120 h of incubation. However, scanning electron microscopy revealed that much greater numbers of the yeasts colonized the saliva- or serum-coated lining material than the lysozyme-, mucin-coated or control material. Hyphal invasion was observed in saliva-coated lining material. These results suggested that denture pellicle derived from saliva and/or serum may potentiate candidal colonization of denture lining materials.
Adhesiveness↗
The fungicidal effect of human lactoferrin on Candida albicans and Candida krusei.
Five oral isolates each of Candida albicans and Candida krusei were studied for their sensitivity to the fungicidal effect of human lactoferrin. Significant inter- and intraspecies variations were observed and with most isolates the sensitivity of C. krusei to lactoferrin was greater than that of C. albicans. Fungicidal activity of lactoferrin was dose-dependent and observable only with the iron-free form of the molecule (apo-lactoferrin). Iron-saturated lactoferrin was ineffective against all isolates. Supernatant protein assays and scanning electron microscopy indicated cell surface alterations--leakage of proteins and formation of surface blebs--only in those Candida isolates that were sensitive to apo-lactoferrin. As lactoferrin is a common, non-immune, mucosal defence protein, its varying mode of action against C. albicans and C. krusei may be related to their different oral carriage rates.
Analysis of Variance↗
The in vitro lysozyme susceptibility of Candida albicans cultured in carbohydrate-supplemented media.
The in vitro lysozyme susceptibility of three oral isolates of Candida albicans cultured in carbohydrate-supplemented media was studied. Lysozyme was shown to have a dose- and time-dependent killing effect on C. albicans isolates. Fungicidal activity persisted to varying degrees when yeast isolates were cultured in a variety of carbohydrates (glucose, galactose, sucrose, maltose, xylitol and lactose) before exposure to 20 micrograms/ml lysozyme. Sucrose and galactose grown yeasts exhibited increased resistance to lysozyme compared with (in decreasing order) those grown in glucose, maltose, xylitol or lactose. Further, the C. albicans isolates tested demonstrated strain variations in their susceptibility to lysozyme. These results suggest that dietary carbohydrate may play a role in modulating the yeast cell populations in the oral cavity by altering the fungal susceptibility to salivary lysozyme.
Analysis of Variance↗