Susceptibility to ketoconazole of Candida albicans strains from sequentially followed HIV-1 patients with recurrent oral candidosis

The MIC values of the antifungal drug ketoconazole were evaluated on 66 Candida albicans strains. These strains were isolated from 26 HIV-1 infected patients with oral recurrent candidosis. Each episode of oral candidosis observed in these patients was orally treated with ketoconazole (200 mg/day) until the clinical disappearance of the lesions. The most frequent MIC values were 20 micrograms/ml and 10 micrograms/ml, observed in 37 and 19 isolates respectively. Only strains from five patients showed changes in their susceptibility to ketoconazole. This fact could indicate that a different strain causes the subsequent reappearance of the oral lesions, rather than the drug selecting resistant fungal strains. Our results stress the role of host characteristics in the occurrence of candidal infections, pointing to the progressing failure of the immunological response as the most important factor responsible for the recurrence of oral candidosis during HIV-1 infection.     

Molecular genetics of pathogenic fungi: some recent developments and perspectives

The diagnosis and the treatment of fungal diseases remains problematic in many cases. Difficulties in diagnosis are due (1) to the ubiquitous presence of fungal pathogens that may lead to false positive test results and (2) to difficulties in the evaluation of the aetiological significance of these pathogens. The relatively small number of effective antifungal agents reflects to a large extent on the fact that many aspects of fungal physiology and virulence are not well understood. The methods of molecular genetics provide effective tools for the diagnosis of mycoses and may also contribute to the identification of new targets for antifungals by genetic analyses of fungal virulence. During the last 3 years molecular genetic methods have been developed for the asexual pathogen Candida albicans that may be used for strain identification. This success indicates a general use of molecular genetics for the analysis of fungal pathogenesis.     

Introduction

Summary: Oral candidosis is the manifestation of candidosis earliest described. In fact pertinent cases are already to be found in the corpus hippocraticum. Exactly 150 years ago a fungus was found in lesions of orogastrointestinal candidosis by the German surgeon Langenbeck. For a long time, there was much dispute on the proper term for the most important causative organism of thrush and correspondingly for the proper name of the diseases caused. Today, Candida albicans is accepted by virtually everybody and the discussion on the name of the disease only focuses on the terms can-didiasis and candidosis of which the latter seems preferable. Facing the scientific progress in the field of Candida and candidosis research and the permanent change of both the causative organism and the corresponding disease in the age of the HIV-infection (AIDS), it seems rewarding to review epidemiology, microbiology, nosology and treatment of oral and gastrointestinal candidosis.     

Hydrolytic enzymes as virulence factors of Candida albicans

Candida albicans is a facultative pathogenic micro-organism that has developed several virulence traits enabling invasion of host tissues and avoidance of host defence mechanisms. Virulence factors that contribute to this process are the hydrolytic enzymes. Most of them are extracellularly secreted by the fungus. The most discussed hydrolytic enzymes produced by C. albicans are secreted aspartic proteinases (Saps). The role of these Saps for C. albicans infections was carefully evaluated in numerous studies, whereas only little is known about the physiological role of the secreted phospholipases (PL) and almost nothing about the involvement of lipases (Lip) in virulence. They may play an important role in the pathogenicity of candidosis and their hydrolytic activity probably has a number of possible functions in addition to the simple role of digesting molecules for nutrition. Saps as the best-studied member of this group of hydrolytic enzymes contribute to host tissue invasion by digesting or destroying cell membranes and by degrading host surface molecules. There is also some evidence that hydrolytic enzymes are able to attack cells and molecules of the host immune system to avoid or resist antimicrobial activity. High hydrolytic activity with broad substrate specificity has been found in several Candida species, most notably in C. albicans. This activity is attributed to multigene families with at least 10 members for Saps and Lips and several members for PL B. Distinct members of these gene families are differentially regulated in various Candida infections. In future, prevention and control of Candida infections might be achieved by pharmacological or immunological tools specifically modulated to inhibit virulence factors, e.g. the family of Saps.     

Candidosis of the prostate: a rare form of endomycosis

The third case of a culturally and histologically proven candidosis of the prostate in the world literature available to us is reported. Autopsy of a 59-year-old man with metastasizing bronchial carcinoma as predisposing primary disease revealed a local candidosis of the prostate in the left lobe of the prostate, without evidence of a Candida sepsis. Parallel and different aspects in comparison with the other two cases are described.     

Temporal events in the intravenous challenge model for experimental Candida albicans infections in female mice

We characterized the intravenous (i.v.) challenge model for disseminated Candida albicans infection in female BALB/c and DBA/2 mice. Clearance of fungi from the bloodstream and appearance of fungi in tissues were measured at intervals after challenge with various doses of C. albicans. The wild-type isolate SC5314 and derived strains CAF2-1 and CAI-4 transformed with CIp10 were of equal virulence in the model. Variability in mouse survival times, kidney fungal burdens and cachexia was lowest when challenge inocula were within the range 10(4)-10(5) CFU g(-1) body weight in BALB/c mice, but brain fungal burdens and outcomes in DBA/2 mice were variable for all inocula tested. Critical times in the development of infections in optimally challenged BALB/c mice were at 5-10 h (bloodstream fully cleared of fungi), 24 h (start of exponential fungal growth in kidneys) and 48 h (50% of blood cultures become positive). Differential involvement of right and left kidneys occurred almost exclusively in mice challenged with <2 x 10(4) CFU g(-1). We conclude that the i.v. challenge model in female BALB/c mice is now sufficiently well characterized to permit more refined experimentation in future virulence studies with C. albicans mutants.     

Hohe Phospholipase A-Aktivität von Candida albicans aus dem Darm von Psoriatikern/High Phospholipase A-Activity of Candida albicans Isolated from the Intestine of Psoriatic Patients

Zusammenfassung: Phospholipase-Aktivität von Candida albicans -Stämmen wurde mit einer Agarplatten-Methode unter Zusatz von Eigelb bestimmt. 11 Stämme aus Stuhlproben von Psoriatikern wurden mit 35 C. albicans -Stämmen aus Stuhlproben von Patienten mit der Verdachts-Diagnose auf intestinalen Soorbefall verglichen. Die Enzymaktivitäten aller Stämme wurden mit derjenigen eines hoch pathogenen C. albicans Stammes verglichen, der in einem Septikämiemodell an Albinomäusen verwendet wird. Die Stämme aus den Psoriatikern wiesen 81 ± 30% der Enzymaktivität des Referenzstammes auf, wogegen die Stämme aus dem Kontrollkollektiv nur 46 ± 28% der Enzymaktivität des Referenzstammes zeigten. Die Unterschiede sind signifikant (Irrtumswahrscheinlichkeit < 0,001). Es bleibt zu klären, ob diese Enzym-Freisetzung einer Hefe im Darm den Ausbruch von psoriatischen Hautveränderungen bewirkt.
Summary: Phospholipase activity of Candida albicans strains was measured by means of an agar plate method containing egg yolk. 11 strains, isolated out of feces samples from patients suffering from psoriasis were compared with 35 strains of C. albicans , isolated from patients with suspected diagnosis of intestinal candidosis. The enzymatic activity of all strains was compared with the activity of a highly pathogenic strain of C. albicans from an intravenous animal infection model. The psoriasis derived strains exhibited 81 ± 30% activity of the reference strain, whereas the strains derived from intenstinal candidosis exhibited only 46 ± 28% enzymatic activity of the reference strain. The mean values are significantly different (p < 0,001). It remains to be investigated whether this enzyme activity of yeast cells in the gut triggers the eruption of psoriasis on the skin.     

Introduction

Summary: Oral candidosis is the manifestation of candidosis earliest described. In fact pertinent cases are already to be found in the corpus hippocraticum. Exactly 150 years ago a fungus was found in lesions of orogastrointestinal candidosis by the German surgeon Langenbeck. For a long time, there was much dispute on the proper term for the most important causative organism of thrush and correspondingly for the proper name of the diseases caused. Today, Candida albicans is accepted by virtually everybody and the discussion on the name of the disease only focuses on the terms can-didiasis and candidosis of which the latter seems preferable. Facing the scientific progress in the field of Candida and candidosis research and the permanent change of both the causative organism and the corresponding disease in the age of the HIV-infection (AIDS), it seems rewarding to review epidemiology, microbiology, nosology and treatment of oral and gastrointestinal candidosis.     

Systemic neonatal candidosis: the karyotyping of Candida albicans strains isolated from neonates and health-workers

Candida albicans has become an important cause of nosocomial infections in neonatal intensive care units (NICUs). The aim of the present study was to compare C. albicans strains isolated from neonates (NN) suffering from systemic candidosis and from nurses in order to determine the relatedness between NN and health workers' strains. Thirty-one C. albicans strains were isolated from 18 NN admitted to the NICU of the neonatology service of Farhat Hached Hospital of Sousse, Tunisia and suffering from systemic candidosis, together with five strains recovered from nurses suffering from C. albicans onychomycosis. Two additional strains were tested, one from an adult patient who developed a systemic candidosis and the second from an adult with inguinal intertrigo. All strains were karyotyped by pulsed-field gel electrophoresis (PFGE) with a CHEF-DR II system. Analysis of PFGE patterns yielded by the 38 strains tested led to the identification of three pulsotypes that were designated I, II and III, and consisted of six chromosomal bands with a size ranging from 700 to >2500 kbp. The most widespread was the pulsotype I, which was shared by 17 NN and the five nurses' strains. The identity between NN and nurses' strains is very suggestive of a nosocomial acquisition from health-workers.     

Interest of biotyping Candida albicans in chronic vulvovaginitis

Chronic vulvovaginitis due to Candida albicans is a major clinical problem for the physician. Although new antifungal drugs are now available, the therapeutic approach of this disease remains disappointing. The aims of this study were two-fold. First, we wanted to evaluate the reliability of a single sampling performed by most clinicians in verifying if the yeast infects the entire genital mucosa or a preferential site and, second, to biotype the strains recovered in order to see if more than one strain are responsible for the infection. We found, in 18 patients suffering from vaginal candidosis, that the entire genital mucosa was infected by the yeast and the strain recovered from the different genital sites in a single patient was the same in 100% of the cases. Only 1.4% of the samples were negative. In addition, we biotyped the strains obtained from the gastrointestinal tract of these patients to evaluate this site as a potential source of infection. We obtained gastrointestinal tract samples for 15 of the 18 patients and we could identify C. albicans in 100% of the cases. Furthermore, 73.3% of the patients harboured the same strains of C. albicans in the gastrointestinal tract as in the vagina.     

Intracellular killing of Candida albicans by human neutrophils is potentiated by exposure to combinations of amphotericin B and 5-fluorocytosine

Combination treatment with amphotericin B and 5-fluorocytosine is synergistic and has become clinically useful in the treatment of various forms of systemic candidosis. The synergy between these two compounds may be explained in part by their combined effect on the interaction between fungal cells and host phagocytes. Pretreatment of Candida albicans for 2 h with either amphotericin B or 5-fluorocytosine or the two agents in combination did not inhibit or enhance phagocytosis by glass-adherent human neutrophils (P greater than 0.05). Intracellular killing of pretreated yeast cells was not influenced by antifungals alone (P greater than 0.05), but pretreatment of C. albicans with 5.0 mg l-1 amphotericin B + 10 l-1 5-fluorocytosine or 5.0 mg l-1 amphotericin B + 50 mg l-1 5-fluorocytosine significantly enhanced the ability of neutrophils to kill the number of viable yeast cells intracellularly (P less than 0.001).     

Zum Candidose-Risiko bei Patienten mit endokrinen Dysfunktionen: Risk of Candidosis in Patients with Endocrinological Disorders

Zusammenfassung: Bei 144 Kranken mit verschiedenen Endokrinopathien ohne klinisch erkennbare Candidose wurden Candida-Pilze bei 64,6 + 3,9 % der Patienten nachgewiesen. Aufgrund von Keimzahlbestinunungen wurde eine Risikogruppe definiert, zu der 25,7 + 3,7% der untersuchten Patienten zu zählen waren. Im Gegensatz dazu konnten bei 46 gesunden Personen diese Pilze nur von 33,6 + 6,9% isoliert werden, wobei keine Person zur Risikogruppe zu rechnen war. Der höchste Prozentsatz des Nachweises von Candida-Pilzen (81,1 + 4,7%) und die größte Candidose-Risikogruppe (36,5 + 5,7%) wurde bei Zuckerkranken festgestellt. Es wird darauf hingewiesen, daß die Isolierung von Candida-Pilzen und das Auftreten des Candidose-Risikos von der Dauer und der Schwere der Grundkrankheit unmittelbar abhängen. Eine laufende ambulante Kontrolle der der Risikogruppe angehörenden Patienten ist notwendig. Dabei sind wiederholte mykologische Untersuchungen durchzuiuhren, um der Entstehung einer sekundären Candidose bei diesen Personen vorzubeugen.
Summary: In 144 patients with different endocrinological disorders and without apparent candidosis Candida species were found in 64.6%. A candidosis-risk-group was defined on the basis of a quantitative determination of yeasts in biological material. Thus, 25.7 + 3.7% of the patients were found to belong to this group. In contrast, only 33.6 + 6.9% of healthy controls were colonized with Candida species, and none of the healthy persons belonged to the risk group. Patients suffering from diabetes presented the highest proportion of Candida isolates (81.1 + 4.7 %) and of the candidosis-risk-group (36.5 + 5.7 %). Severity and duration of diabetes are directly related to the incidence of Candida colonization and risk of candidosis. Repeated mycological controls are required in order to prevent manifest candidosis in these patients.     

Role of pH response in Candida albicans virulence

Over 25 years ago it was noted that the pH of the culture medium influenced germ tube formation of Candida albicans, an opportunistic fungal pathogen. This simple observation has been the stimulus for a number of investigations to discern the mechanisms controlling this response and the significance of this response to the biology of C. albicans. Recent studies have demonstrated that a signaling pathway conserved in several fungal species regulates this morphological response to ambient pH and controls the pH-conditional expression of multiple genes. Significantly, C. albicans responds to the pH of the host niche and this response is critical for virulence.     

Adhesion of clinical Candida albicans isolate to buccal epithelial cells

Mucosal adherence and germ tube formation are considered to be important virulence factors of C. albicans. Adherence is a precondition for colonisation and invasion. We investigated 11 clinical isolates (among them 5 cases recovered from oesophageal thrush) for quantification of the two characteristics and correlated the results with clinical data. Adherence was measured on buccal epithelial cells and the continuous flow culture was used for quantification of germ tube formation. Adherence of strains recovered from clinically, culturally and serologically confirmed oesophageal thrush adhered stronger to buccal epithelial cells than isolates from patients with heavy colonisation without signs of candidosis. Strains with stronger adherence showed a significantly faster and an increased germ tube formation in the continuous flow culture. Strains from oesophageal thrush therefore show a more marked expression of the investigated virulence factors. Therefore a good adherence is a necessity for infection of the oesophagus by C. albicans. The preferential isolation of C. albicans from oesophageal thrush (> 90%) supports this assumption.     

The involvement of physico-chemical interactions in the adhesion of Candida albicans and Candida dubliniensis to epithelial cells

Candida albicans and Candida dubliniensis are two pathogenic yeasts particularly hazardous to immunocompromised patients. Adhesion of yeast cells to epithelium is considered one of the virulence factors and its study is of major importance. The main aim of this study was the comparison of the influence of physico-chemical properties on the adhesion of C. albicans and C. dubliniensis to epithelium. Two strains of each Candida species were used in the adhesion assays to HeLa cells. Adhered cells were enumerated by direct microscopic images observation. Yeast cell surface tension parameters and degree of hydrophobicity were determined by contact angle measurement. Pseudohyphae and hyphae formation was analysed by scanning electron microscopy. Yeast cells presented no statistical differences concerning their physico-chemical surface properties. However, the extent of adhesion to epithelium was different among the four strains. As general conclusion, yeast adhesion to epithelium seems to be strain-dependent and not directly correlated with pseudohyphae formation.     

Disseminated candidiasis in premature twins. Case report

A case of disseminated candidosis in a premature newborn twin I (26th weeks of pregnancy) is reported. A severe mycotic infection of the organs, especially the kidneys was present. Even Candida in the pancreatic islets of Langerhans cells could be demonstrated. Twin II also suffered a Candida infection but in contrast to twin I she survived after therapy. Candida infection of twins is rarely reported in the literature.     

Change of Causative Organisms under Antifungal Treatment in Immunosuppressed Patients with HIV-Infections

Summary: Oral and esophageal candidosis are very common in HIV-infected patients. Due to the lack of efficacy of topical antimy-cotics in advanced stages of HIV-infection oral azoles are mainly used for treatment. holes most often used are ketoconazole and fluconazole. While Candida albicans clearly is the most frequently encountered yeast before and after treatment other species can be found somewhat less frequently after treatment. This especially applies to Candida glabrata. Candida spp. other than C. albicans obviously may cause manifest oral candidosis. This shift of microbes deserves the more interest as they are less susceptible to azole drugs.     

Utility of the oestrogen-dependent vaginal candidosis murine model in evaluating the efficacy of various therapies against vaginal Candida albicans infection

The efficacy of yogurt treatment against vaginal candidosis (VC) was examined using an oestrogen‐dependent vaginal candidosis (EDVC) murine model. The EDVC mouse model was constructed by inoculating mice with viable Candida albicans cells under pseudo‐oestrus conditions. Vaginal fungal burden in the various mouse groups was evaluated at several time points following the induction of VC. Untreated and yogurt‐treated naïve mice exhibited background levels of VC (<6000 CFU per mouse). Candida albicans colonisation in untreated EDVC mice was significantly higher (P < 0.05) than that in yogurt‐treated EDVC mice at days 20–30. Metronidazole‐treated naïve mice developed persistent C. albicans vaginal colonisation at significantly lower levels (P < 0.05) than that in untreated or metronidazole‐treated EDVC mice. Lactobacillus was only detected in the reproductive tracts of yogurt‐treated naïve and EDVC mice. These findings suggest that the presence of Lactobacillus in the reproductive tract can suppress C. albicans growth and the antibiotics may predispose to VC.     

Habitats for Candida in medical and hygienic respects

The at present acknowledged 163 species of the genus Candida are living in different habitats. Agents of human candidosis have a comparatively restricted natural distribution, and have been discovered primarily in association with men and animals. Candida albicans holds an exceptional position opposite to the nearly 20 non-C. albicans-species with medical importance. Primary habitat is the digestive tract of men and warm-blooded animals. C. albicans is not ubiquitously distributed in the nature. Carriers of Candida may contaminate their immediate environment with yeasts, but that contamination does not usually spread far. C. albicans survives poorly on dry surfaces, a little bit longer in moist materials. Some non-C. albicans-species have their habitat also in the digestive tracts of men and animals, but different to C. albicans they are also ubiquitously distributed in the surroundings (soil, plants, foods, forages) and are much more resistant to environmental influences. The most important source of Candida species in human diseases is endogenous. The via exogen contamination arising mycoses are involved above all by non-C. albicans-species. The different habitats of the Candida species are decisive for the direct and indirect transmission of yeasts to humans and also for the preventive measures against endogenous and exogenous nosocomial Candida mycoses.     

Adhesion and cell-surface-hydrophobicity of sequentially isolated genetic isotypes of Candida albicans in an HIV-infected Southern Chinese cohort

Objectives of the study were to investigate the variability in yeast adhesion and cell-surface-hydrophobicity (CSH) during human immunodeficiency virus (HIV) disease progression, using a total of 60 sequential Candida albicans isolated from oral rinse samples of seven HIV-infected individuals with (4) and without (3) clinical symptoms of oropharyngeal candidosis. Significant differences in the adhesion to buccal epithelial cells (BECs) during sequential visits were observed for all genetic isotypes in five of the seven individuals and three isotypes belonging to the sixth individual. A single isotype of patient HK1 and another of HK4 (genotype I) demonstrated significant variations in their CSH during sequential visits whereas no such differences were noted for the remaining genotypes. On Spearman correlation analysis an isotype from HK1 demonstrated a significant increased adherence to BECs and CSH during HIV disease progression whereas no such correlation was noted for the remaining isotypes studied. No significant differences in adherence to BECs or CSH values were observed between the symptomatic oral candidosis and the asymptomatic carrier group. Further, on regression analysis only the single isotype of HK1 demonstrated a significant positive correlation between adherence to BECs and CSH whereas no such correlation was observed when all tested Candida isolates were pooled and evaluated as a single, large group.