Variation in adhesion and cell surface hydrophobicity in Candida albicans white and opaque phenotypes

A previous study had established that a select group of pathogenic isolates of Candida albicans was capable of switching heritably, reversibly and at a high frequency (10(-2) to 10(-3)) between two phenotypes ('white' or 'opaque') readily distinguishable by the size, shape, and color of colonies formed on agar at 25 degrees C. This paper describes experiments designed to determine the ability of these two phenotypes to attach to buccal epithelial cells (BECs) and plastic, and to compare the cell surface hydrophobicities of white and opaque phenotypes from three clinical isolates. 'White cells' were found to be significantly more adhesive to BECs, and a strong correlation was also found between phenotype adhesiveness and the percentage of BECs to which C. albicans had attached. The percentage of BECs with one or more attached C. albicans was approximately 90% for the white phenotype and approximately 50% for the opaque phenotype. 'Opaque cells', in contrast, were twice as hydrophobic as white cells, and the percentage of opaque cells bound to BECs by coadhesion was also double that of white cells. The differences in adhesion to plastic between the two phenotypes were not statistically significant and there was no distinct trend to suggest which phenotype might be more adhesive to plastic. These results indicate that several factors are involved in the adhesion of C. albicans to plastic, and confirm the hypothesis that cell surface hydrophobicity is of minor importance in direct adhesion to epithelial cells but that it may contribute to indirect attachment to epithelial cells by promoting yeast coadhesion.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of growth conditions on Candida albicans adhesion, hydrophobicity and cell wall ultrastructure

The effect of cultivation in 13 media (10 complex, and three synthetic), as well as altering growth conditions, on Candida albicans adhesion, cell surface hydrophobicity and cell wall ultrastructure was studied. Adhesion of C. albicans to buccal epithelial cells (BECs) was significantly modified by all of the factors tested, particularly growth medium. In general, optimal adhesive activity for C. albicans was observed when the cells were grown in defined media (depending on the carbohydrate used) and/or at 25 degrees C. Moreover, significant differences in adhesion to BECs were noted when C. albicans was grown in the same complex medium from different manufacturers and in different batches of medium from the same manufacturer. Electron microscopy revealed significant differences in surface topography and cell wall ultrastructure of C. albicans grown in different media but none of these differences, including presence or absence of an outer floccular layer, appeared to correlate with the adhesive changes noted, which raises questions regarding the location and nature of the Candida adhesin(s). Likewise, cell surface hydrophobicity could not be correlated with adhesion to BECs but may have influenced yeast coadhesion. The results indicate that Candida adhesion is highly dependent upon the cultivation conditions of the yeast cells tested, and may explain discrepancies in the literature regarding the biochemical nature of the surface component(s) responsible for C. albicans adhesion.

Relapsing large cell immunoblastic lymphoma complicating well-differentiated lymphocytic lymphoma: a report of two cases showing prolonged survival with therapy

Two patients presented with co-existing large cell immunoblastic and well-differentiated lymphocytic lymphomas. Prolonged remissions from the large cell lymphomas were achieved following intensive combination chemotherapy but both patients suffered relapses after many years. Previous reports have grouped such patients with those developing classical Richter's syndrome implying a uniformly poor prognosis. This report suggests that this is not the case. It was not possible with immunohistochemical stains to prove or disprove that these tumours had the same stem cell origins.

Mechanisms of association of Candida albicans with intestinal mucosa

The association of Candida albicans with gastrointestinal (GI) mucosal surfaces was studied in vitro and in vivo. The caecal mucosal surfaces from antibiotic-treated and untreated control mice challenged orally with C. albicans revealed that large numbers of C. albicans were associated with the intestinal epithelium of antibiotic-treated mice but not with that of the control mice that possessed an indigenous wall-associated bacterial flora. Moreover, Candida cells only penetrated deep into the mucosa of animals in which the ecology of the intestinal microflora had been disrupted. In mice given antibiotics, C. albicans was associated with the mucosa of all areas of the GI tract; the caecal mucosa had the most associated Candida, whereas the stomach and small intestine had very few associated yeasts. Further examination of caecal mucosa from antibiotic-treated mice showed that C. albicans associated with the mucosa by at least five distinct mechanisms. These included: adhesion to epithelium, adhesion to mucus, co-adhesion to adherent fungi, co-adhesion to adherent bacteria, and entrapment in the mucous gel overlying the epithelium. The cell-surface hydrophobicity of C. albicans also was examined and found not to play a role in Candida adhesion to intestinal mucosa. The predominant association mechanisms appeared to be entrapment in the mucous gel, and adhesion to mucus and the epithelium. The ecological and pathological significance of co-adhesion by C. albicans to attached organisms is unclear but it may be important in the initiation of mucosal lesions.

Role of motility, chemotaxis, and adhesion in microbial ecology

This review emphasized the implications of recent data pertaining to the role that motility, chemotaxis, and adhesion play in microbial ecology. Some of these processes appear to promote colonization by allowing certain organisms to selectively "seek out" nutrients or sites of colonization. For example, chemotaxis to NO3- and NO2- may provide pseudomonads with such a strong competitive mechanism that it allows this group of bacteria to outcompete other members of the soil microbiota for these chemicals. Likewise, chemotaxis also allows other bacteria to enter and colonize the mucus gel lining the intestinal epithelium and thereby resist physical removal from the gut. On the other hand, the understanding of such mechanisms offers important new possibilities for the deliberate control of microorganisms for the benefit of man. To that end, much remains to be done before a thorough understanding of the ecology of the microflora of any ecosystem can be accomplished. It is hoped that this review will stimulate further work in this area, as well as to lead to collaboration between engineers and microbiologists, which should lead to fruitful and exciting research in the future.

Potentiation of small cell lung cancer-related SIADH by trifluoperazine

The syndrome of inappropriate anti-diuretic hormone secretion (SIADH) is a feature of approximately 7% of cases of small cell lung cancer (SCLC). The elaboration of peptide hormones by this tumour is well recognised and cerebral oedema resulting from inappropriate ADH secretion may be a life-threatening complication of this illness, requiring prompt intervention. We report a patient with SCLC who presented with SIADH which worsened abruptly each time he was treated with trifluoperazine for a co-existing psychosis.

Paraneoplastic papilloedema in neuroblastoma

We report a case of bilateral papilloedema in an adult male with neuroblastoma, in the absence of hypertension or detectable intracranial disease. This complication has not previously been described in the English-speaking literature. Possible mechanisms are discussed.

Encephalitis caused by a Sarcocystis-like organism in a steer

Sarcocystis spp can cause poor growth, anorexia, fever, anemia, muscular weakness, nervousness, abortion, and even death in cattle. Lesions in the CNS of cattle infected with Sarcocystis spp are microscopic and relatively minor, compared with those in other organs. We report extensive encephalitis in a steer attributable to a Sarcocystis-like organism.

First record of Lipoptena depressa (Diptera: Hippoboscidae) from Alberta, Canada

Lipoptena depressa is reported for the first time from Alberta on a 2 1/2-mo-old white-tailed deer fawn. This ked fly is one of four species occurring on deer in North America. The fawn had severe hemorrhagic enteritis of undetermined cause.

Uptake and distribution of bupivacaine in fetal lambs

Direct continual measurement of placental drug transfer was introduced to evaluate more precisely the fetal uptake of a commonly used local anesthetic in obstetrics. Bupivacaine, 2.7 mg X kg-1 (base), was infused at a constant rate over 1 h into a maternal jugular vein of five chronically prepared pregnant ewes. Blood was sampled simultaneously from the umbilical vein (UV), fetal aorta (FA), and a maternal artery (MA). Fetal uptake rate was determined from the product of the bupivacaine UV-FA blood concentration difference and the umbilical flow rate (Qu). Total fetal accumulation was determined by integrating uptake rate over 5 h. Correlation of total fetal uptake and the infused mean maternal dose (r = 0.993, P less than 0.001) indicated that during the infusion, mean fetal uptake was a constant fraction (0.16) of the maternal infused dose. Total fetal uptake was linear despite wide individual changes in Qu, suggesting that within limits fetal accumulation is not Qu-dependent. Mean ovine protein binding of bupivacaine by maternal and fetal whole blood was 85.49% +/- 2.61 (SD) and by fetal blood, 40.43% +/- 9.60 (SD). Back-transfer of bupivacaine to the mother proceeded against a higher total bupivacaine concentration because unbound unionized drug concentrations in maternal blood were less than in fetal blood. At maternal-fetal equilibrium when UV and FA total blood concentrations were equal, the calculated fetal/maternal concentration ratio (f/m) (0.36) determined from the maternal and fetal protein binding and pH closely approximated the observed (0.35). The f/m increased during both fetal uptake and back-transfer and cannot be considered a good index of placental transfer.(ABSTRACT TRUNCATED AT 250 WORDS)

Ecology of Candida albicans gut colonization: inhibition of Candida adhesion, colonization, and dissemination from the gastrointestinal tract by bacterial antagonism

Antibiotic-treated and untreated Syrian hamsters were inoculated intragastrically with Candida albicans to determine whether C. albicans could opportunistically colonize the gastrointestinal tract and disseminate to visceral organs. Antibiotic treatment decreased the total population levels of the indigenous bacterial flora and predisposed hamsters to gastrointestinal overgrowth and subsequent systemic dissemination by C. albicans in 86% of the animals. Both control hamsters not given antibiotics and antibiotic-treated animals reconventionalized with an indigenous microflora showed significantly lower gut populations of C. albicans, and C. albicans organisms were cultured from the visceral organs of 0 and 10% of the animals, respectively. Conversely, non-antibiotic-treated hamsters inoculated repeatedly with C. albicans had high numbers of C. albicans in the gut, and viable C. albicans was recovered from the visceral organs of 53% of the animals. Examination of the mucosal surfaces from test and control animals indicated further that animals which contained a complex indigenous microflora had significantly lower numbers of C. albicans associated with their gut walls than did antibiotic-treated animals. The ability of C. albicans to associate with intestinal mucosal surfaces also was tested by an in vitro adhesion assay. The results indicate that the indigenous microflora reduced the mucosal association of C. albicans by forming a dense layer of bacteria in the mucus gel, out-competing yeast cells for adhesion sites, and producing inhibitor substances (possibly volatile fatty acids, secondary bile acids, or both) that reduced C. albicans adhesion. It is suggested, therefore, that the indigenous intestinal microflora suppresses C. albicans colonization and dissemination from the gut by inhibiting Candida-mucosal association and reducing C. albicans population levels in the gut.

Effect of various antibiotics on gastrointestinal colonization and dissemination by Candida albicans

Mice were treated orally with various antibiotics to determine which members of the indigenous intestinal microflora normally suppress Candida albicans colonization and dissemination from the gastrointestinal (GI) tract. The mice were given penicillin, clindamycin, vancomycin, erythromycin, or gentamicin for 3 days, and then challenged orally with C. albicans. Penicillin, clindamycin, and vancomycin, but not gentamicin or erythromycin, decreased the total anaerobic bacterial populations in the animals ceca, and increased the enteric bacilli population levels. All three of the former antibiotics allowed C. albicans to proliferate in the gut and, subsequently, disseminate from the GI tract to visceral organs. The ability of C. albicans to associate with intestinal mucosal surfaces was also tested. It was found that antibiotics which reduced anaerobic population levels, but not enteric bacilli or aerobes, also predisposed animals to mucosal association by C. albicans. It is suggested that the strictly anaerobic bacterial populations which predominate in the gut ecosystem are responsible for the inhibition of C. albicans adhesion, colonization and dissemination from the GI tract.

Role of chemotaxis in the ecology of denitrifiers

A modification of the Adler capillary assay was used to evaluate the chemotactic responses of several denitrifiers to nitrate and nitrite. Strong positive chemotaxis was observed to NO(3) and NO(2) by soil isolates of Pseudomonas aeruginosa, Pseudomonas fluorescens, and Pseudomonas stutzeri, with the peak response occurring at 10 M for both attractants. In addition, a strong chemoattraction to serine (peak response at 10 M), tryptone, and a soil extract, but not to NH(4), was observed for all denitrifiers tested. Chemotaxis was not dependent on a previous growth on NO(3), NO(2), or a soil extract, and the chemoattraction to NO(3) occurred when the bacteria were grown aerobically or anaerobically. However, the best response to NO(3) was usually observed when the cells were grown aerobically with 10 mM NO(3) in the growth medium. Capillary tubes containing 103 M NO(3) submerged into soil-water mixtures elicited a significant chemotactic response to NO(3) by the indigenous soil microflora, the majority of which were Pseudomonas spp. A chemotactic strain of P. fluorescens also was shown to survive significantly better in aerobic and anaerobic soils than was a nonmotile strain of the same species. Both strains had equal growth rates in liquid cultures. Thus, chemotaxis may be one mechanism by which denitrifiers successfully compete for available NO(3) and NO(2), and which may facilitate the survival of naturally occurring populations of some denitrifiers.

Dissemination of yeasts after gastrointestinal inoculation in antibiotic-treated mice

Mice pretreated with antibiotics were inoculated intragastrically with different yeast isolates to determine whether the resulting disruption of the normal flora ecology would allow certain fungi to colonize and disseminate from the gastrointestinal tract. Antibiotic treatment decreased the total population levels of the indigenous bacterial flora, and predisposed mice to gastrointestinal overgrowth and subsequent dissemination by Candida albicans, C. parapsilosis, C. pseudotropicalis, C. tropicalis, and Torulopsis glabrata. A clinical isolate of Rhodotorula rubra, on the other hand, was unable to maintain a stable population in the gut of similar mice and could not be isolated from systemic organs. Control animals not receiving antibiotic therapy, challenged with C. albicans, showed significantly lower gut population levels of yeasts, and Candida organisms could not be grown from visceral organs. It is suggested that suppression of fungi within the gastrointestinal tract by members of the normal bacterial flora may be an important mechanism whereby fungi are confined to the alimentary tract.

Activities of an employer independent Occupational Medicine Clinic, Cook County Hospital, 1979-1981

In July 1976, Cook County Hospital, a 1,363-bed general public hospital in Chicago, Illinois, established a hospital-funded Occupational Medicine Clinic. A review was made of the clinic records of the 486 new patients evaluated at the clinic from July 1979 to June 1981. Information is presented concerning age, ethnic origin, sex, union representation, referral sources, reason for the referral, number and type of toxic exposure, diagnosis, occupational relationship of the disease, and disposition.

Gastrointestinal inoculation of Sporothrix schenckii in mice

Antibiotic-decontaminated and untreated conventional mice were inoculated intragastrically with 10(7) viable cells of Sporothrix schenckii to compare the incidence of gastrointestinal (GI) colonization. In control mice, S. schenckii was completely eliminated from the GI tract by 12 h post-inoculation. Antibiotic-treated mice also failed to become colonized with this fungus, however, higher population levels of Sporothrix cells remained in the GI tract for a longer period of time before being eliminated. The ability of S. schenckii to disseminate from the lumen of the bowel to infect other organs was also tested. Results indicate that the gastrointestinal tract is not a portal of entry into the host for S. schenckii.

Use of sodium taurocholate to enhance spore recovery on a medium selective for Clostridium difficile

Isolation of Clostridium difficile from fecal specimens has been facilitated by the development of a selective and differential medium, cefoxitin-cycloserinefructose agar (CCFA). We substituted 0.1% sodium taurocholate for the 2.5% egg yolk in CCFA and compared the growth of 15 isolates of C. difficile on the resulting medium with growth on conventional CCFA. The taurocholate-containing medium (TCCFA) quantitatively recovered vegetative forms of C. difficile in the same numbers as CCFA medium. Recovery of spores was a mean 1.7 log(10) higher on TCCFA than on CCFA. Thirty-six of 60 patient stool specimens growing C. difficile gave a heavier growth on TCCFA than on CCFA, and 9 failed to yield C. difficile on CCFA. TCCFA detected spores of 75 colony-forming units per ml from artificially inoculated fecal specimens when conventional stool culturing techniques were used. Fluorescence of colonies of C. difficile was more intense on TCCFA than on CCFA. TCCFA was simpler to prepare and, overall, was more sensitive than CCFA.