Fungal infections associated with HIV infection

Comparing the therapeutic potentials of Lactobacillus johnsonii vs. Lactobacillus acidophilus against vulvovaginal candidiasis in female rats: an in vivo study

Background

Vulvovaginal candidiasis (VVC) is a highly prevalent illness affecting women globally. Lactobacilli, which make up the majority of healthy vaginal microbiota (VMB), serve as a powerful barrier against infections. Probiotic therapy has been recommended for the treatment or prevention of VVC.

Aim of work

To compare the in vivo therapeutic effects of Lactobacillus johnsonii (B-2178) vs. Lactobacillus acidophilus (LA-5^®) on VVC in a rat model, particularly highlighting the immune response of the host vaginal epithelium.

Methods

In total, 30 female Sprague-Dawley rats were divided into 5 groups; Group 1: no intervention, Group 2: ovariectomy group, while animals in Groups 3-5 were subjected to ovariectomy and an intravaginal inoculation of Candida albicans (C. albicans) to establish VVC. The animals in Groups 4 and 5 received intravaginal lactobacilli treatment with L. acidophilus (LA-5^®) and L. johnsonii (B-2178) strains, respectively, for 7 days. C. albicans load was measured in a vaginal lavage 1, 3, and 7 days after the stoppage of the treatment. Histological, morphometric, and immunohistochemical studies of the vaginal tissues were done. IFN-γ, IL-4, and IL-17 were measured in the vaginal tissue.

Results

Both L. johnsonii and L. acidophilus significantly reduced C. albicans vaginal load (250 ± 77.46 and 133.33 ± 40.82 CFU/mL) compared to the count before treatment in both groups (4,850 ± 1419.51 and 4966.67 ± 852.45 CFU/mL) even after 7 days of stoppage of lactobacilli treatment. A statistically significant reduction of the pro-inflammatory cytokines IL-17 and IFN-γ was reported in both treated groups compared to the infected untreated group. L. johnsonii has a significant effect on the reduction of hyphae formation of C. albicans as well as the nuclear factor kappa B (NF-κB) immunostaining density of vaginal tissue compared to L. acidophilus. Moreover, treatment with L. johnsonii significantly minimized the epithelium damage triggered by C. albicans infection and restored normal vaginal architecture as evidenced by the histologic and morphometric studies when compared to L. acidophilus.

Conclusion

Through maintaining an immune tolerant state in the vaginal epithelium and ameliorating the undesirable uncontrolled inflammatory response in the vaginal tissue, L. johnsonii (B-2178) has the potential to be utilized alone or in combination with other lactobacilli species in probiotic clinical trials to treat or prevent VVC.

Oral candidiasis in patients hospitalised in the intensive care unit: Diagnosis through clinical and cytopathological examinations

OBJECTIVE

To evaluate the prevalence and clinical aspects of oral candidiasis in patients hospitalised in the intensive care unit.

METHODS

This is a longitudinal and prospective study that included 48 participants hospitalised in the intensive care unit. Sociodemographic data, presence of systemic disorders, use of medications, laboratory tests, cause of hospital admission, type of breathing, and length of hospital stay were obtained from medical records. Oral clinical inspection and cytopathological examinations were performed on all participants. The diagnosis of clinical candidiasis was based on the presence of clinical alterations together with positive cytopathological examination results. The diagnosis of subclinical candidiasis was based on the absence of clinical lesions and a positive cytopathological examination. The absence of oral candidiasis was considered when the participant did not present oral lesions and had a negative cytopathological examination.

RESULTS

Clinical candidiasis was present in 18.8% of the 48 participants, and 45.8% of them had the subclinical form. Levels of urea (P = 0.005), creatinine (P = 0.009), haemoglobin (P = 0.009), haematocrit (P = 0.011), bands (P = 0.024), international normalised ratio (INR; P = 0.034), types of breathing (P = 0.017), length of hospital stay (P = 0.037), and outcome (P = 0.014) demonstrated statistically significant differences between the groups with and without oral candidiasis.

CONCLUSIONS

Clinical and subclinical forms of oral candidiasis are frequent in intensive care unit patients. Levels of urea, creatinine, haemoglobin, haematocrit, bands, INR, type of breathing, length of hospital stay, and outcome can be associated with the presence of candidiasis.

Burden of fungal infections in Kenya

The burden of fungal infections has been on the rise globally and remains a significant public health concern in Kenya. We estimated the incidence and prevalence of fungal infections using all mycology publications in Kenya up to January 2023, and from neighbouring countries where data lacked. We used deterministic modelling using populations at risk to calculate the disease burden. The total burden of serious fungal infections is estimated to affect 6,328,294 persons which translates to 11.57% of the Kenyan population. Those suffering from chronic infections such as chronic pulmonary aspergillosis are estimated to be 100,570 people (0.2% of the population) and probably nearly 200,000 with fungal asthma, all treatable with oral antifungal therapy. Serious acute fungal infections secondary to HIV (cryptococcal meningitis, disseminated histoplasmosis, pneumocystis pneumonia, and mucosal candidiasis) affect 196,543 adults and children (0.4% of the total population), while cancer-related invasive fungal infection cases probably exceed 2,299 and those in intensive care about 1,230 incident cases, including Candida auris bloodstream infection. The burden of fungal infections in Kenya is high; however, limited diagnostic test availability, low clinician awareness and inadequate laboratory capacity constrain the country's health system in responding to the syndemic of fungal disease in Kenya.

Quantification of Oral Candidal Carriage Rate and Prevalence of Oral Candidal Species in HIV Patients with and Without Highly Active Antiretroviral Therapy

BACKGROUND

Most documents review decrease in the prevalence of HIV related oral lesions to the tune of 10-50% following the advent of HAART. However long term use of HAART on oral health status of HIV infected subjects is poorly documented. Also antifungal agents can effectively treat mucosal candidiasis. However their use can lead to colonization with less susceptible strains among normal susceptible strains.

AIMS AND OBJECTIVES

To know the candidal carriage rate (i.e. presence/absence of candidal growth), candidal density(CFUs/ml) & species variations (species diversity) in HIV positive individuals with and without highly active anti-retroviral therapy (HAART), attending the regional voluntary Counselling and Confidential Testing Centre (VCCTC).

MATERIALS AND METHODS

The study population were categorized into 3 groups. Method followed were Germ tube test, Chlamydospore formation test, CHROM-Agar test.

RESULTS

Quantification comparison study of candidal carriage rate, density with detection of various candidal species in the oral cavity of HIV-positive individuals with and without HAART therapy was conducted.

CONCLUSION

HIV positive individuals with HAART therapy treatment prooved higher candidal carriage rate and lower density than Non-HAART category.

Inhibitory effect of polyunsaturated fatty acids alone or in combination with fluconazole on Candida krusei biofilms in vitro and in Caenorhabditis elegans

The incidence of infections by non-albicans Candida species, including Candida krusei, is increasing. Candida krusei exhibits intrinsic resistance to fluconazole and rapidly develops acquired resistance to other antifungals. Moreover, this yeast can form biofilm with increased resistance. Hence, there is a need to develop novel therapeutic strategies to combat infections caused by this pathogen. One such approach is through combination therapy with natural compounds, such as polyunsaturated fatty acids (PUFAs). This study aims to investigate the effect of PUFAs on fluconazole susceptibility of C. krusei biofilms, as well as the conserved nature of these effects in the Caenorhabditis elegans infection model. C. krusei biofilms were exposed to various fatty acids as well as combinations of fluconazole and linoleic acid (LA) or gamma-linolenic acid (GLA). The effect of these treatments on biofilm formation, cell ultrastructure, membrane integrity, oxidative stress and efflux pump activity was evaluated. In addition, the ability of the PUFAs to prolong survival and reduce the fungal burden of infected C. elegans, in the absence and presence of fluconazole, was assessed. Two P|UFAs, LA and GLA had he displayed significant inhibition of C. krusei biofilms and both of them increased the susceptibility of C. krusei biofilm to fluconazole in vitro via induction of oxidative stress, cell membrane damage, and disruption of efflux pump activity. These PUFAs also extended the lifespan of infected nematodes and displayed a potentiating effect with fluconazole in this model. This may pave the way for future studies into novel antifungal drug targets and treatment options.

LAY ABSTRACT

The pathogenic yeast, Candida krusei, is naturally resistant to the antifungal drug, fluconazole. This study finds that polyunsaturated fatty acids, linoleic and gamma-linolenic acid, can inhibit C. krusei and overcome this resistance of in vitro biofilms, as well as in a nematode infection model.

Update on Candida krusei, a potential multidrug-resistant pathogen

Although Candida albicans remains the main cause of candidiasis, in recent years a significant number of infections has been attributed to non-albicans Candida (NAC) species, including Candida krusei. This epidemiological change can be partly explained by the increased resistance of NAC species to antifungal drugs. C. krusei is a diploid, dimorphic ascomycetous yeast that inhabits the mucosal membrane of healthy individuals. However, this yeast can cause life-threatening infections in immunocompromised patients, with hematologic malignancy patients and those using prolonged azole prophylaxis being at higher risk. Fungal infections are usually treated with five major classes of antifungal agents which include azoles, echinocandins, polyenes, allylamines, and nucleoside analogues. Fluconazole, an azole, is the most commonly used antifungal drug due to its low host toxicity, high water solubility, and high bioavailability. However, C. krusei possesses intrinsic resistance to this drug while also rapidly developing acquired resistance to other antifungal drugs. The mechanisms of antifungal resistance of this yeast involve the alteration and overexpression of drug target, reduction in intracellular drug concentration and development of a bypass pathway. Antifungal resistance menace coupled with the paucity of the antifungal arsenal as well as challenges involved in antifungal drug development, partly due to the eukaryotic nature of both fungi and humans, have left researchers to exploit alternative therapies. Here we briefly review our current knowledge of the biology, pathophysiology and epidemiology of a potential multidrug-resistant fungal pathogen, C. krusei, while also discussing the mechanisms of drug resistance of Candida species and alternative therapeutic approaches.

Microbial interactions and immunity response in oral Candida species

Oral candidiasis are among the most common noncommunicable diseases, related with serious local and systemic illnesses. Although these infections can occur in all kinds of patients, they are more recurrent in immunosuppressed ones such as patients with HIV, hepatitis, cancer or under long antimicrobial treatments. Candida albicans continues to be the most frequently identified Candida spp. in these disorders, but other non-C. albicans Candida are rising. Understanding the immune responses involved in oral Candida spp. infections is a key feature to a successful treatment and to the design of novel therapies. In this review, we performed a literature search in PubMed and WoS, in order to examine and analyze common oral Candida spp.-bacteria/Candida-Candida interactions and the host immunity response in oral candidiasis.

Effect of Cinnamomum verum leaf essential oil on virulence factors of Candida species and determination of the in-vivo toxicity with Galleria mellonella model

BACKGROUND

Essential oils (EO) extracted from Cinnamomum verum has been used as an antimicrobial agents for centuries. The effects of C. verum leaf oil against virulence of microorganisms is not well studied yet.

OBJECTIVES

This study evaluates the effect of C. verum leaf oil against three virulence factors of Candida albicans, C. tropicalis and C. dubliniensis and its in-vivo toxicity.

METHODS

Chemical composition of EO was determined using gas chromatography-mass spectrometry (GC-MS). Minimum inhibitory concentration (MIC) was determined using clinical and laboratory standards institute (CLSI) M27-A3 broth microdilution. Effect of EO on initial adhesion was quantified using XTT assay after allowing Candida cells to adhere to the polystyrene surface for 2 h. Biofilm formation of Candida in the presence of EO was quantified using XTT viability assay. Efficacy on reduction of germ tube formation was evaluated using standard protocol. Visualisation of biofilm formation and progression under the EO treatment were done using scanning electron microscope (SEM) and Time lapses microscope respectively. In-vivo toxicity of EO was determined using Galleria mellonella larvae. Chlorhexidine digluconate: positive control.

RESULTS

Eugenol was the main compound of EO. MIC was 1.0 mg/mL. 50% reduction in initial adhesion was achieved by C. albicans, C. tropicalis and C. dubliniensis with 1.0, > 2.0 and 0.34 mg/mL respectively. 0.5 and 1.0 mg/mL significantly inhibit the germ tube formation. MBIC50 for forming biofilms were ≤ 0.35 mg/mL. 1.0 mg/mL prevent biofilm progression of Candida. SEM images exhibited cell wall damages, cellular shrinkages and decreased hyphal formation. No lethal effect was noted with in-vivo experiment model at any concentration tested.

CONCLUSION

C. verum leaf oil acts against virulence factors of Candida and does not show any toxicity.

Dynamic study of oral Candida infection and immune status in HIV infected patients during HAART

OBJECTIVE

To dynamically monitor oral Candida infection, CD4⁺ T lymphocyte counts, CD8⁺ T lymphocyte counts and CD4/CD8 ratios in HIV/AIDS patients during their first year of HAART and to preliminarily explore the relationships between them.

DESIGN

Forty-six patients with HIV/AIDS receiving HAART at the Infection Department of Chongqing Red Cross Hospital were followed for one year. At baseline and 3, 6, and 12 months after HAART initiation, oral rinses were collected and cultured to identify Candida species. Further, blood samples were collected to detect CD4⁺ T lymphocyte counts, CD8⁺ T lymphocyte counts and CD4/CD8 ratios.

RESULTS

The prevalence of OC decreased after HAART initiation (P ＜ 0.05), and Candida albicans was the dominant species isolated from the oral cavity (66/93). At 3, 6 and 12 months after HAART initiation, CD4⁺ T lymphocyte counts were 327.91 ± 138.82, 329.65 ± 142.66 and 319.98 ± 97.90 cells/mm³, respectively, which were significantly higher than the level at baseline (263.39 ± 126.01 cells/mm³) (P = 0.016, P = 0.014, and P = 0.035, respectively). During the first year of HAART, CD4/CD8 ratios increased gradually, and CD8⁺ T lymphocyte counts decreased continually. OC was associated with low CD4⁺ T lymphocyte counts and a low CD4/CD8 ratio. CD4⁺ T lymphocyte counts <200 cells/mm³ and Candida load ≥300 CFU/mL were risk factors for OC (P ＜ 0.05), and oral Candida load was negatively correlated with CD4⁺ T lymphocyte counts and the CD4/CD8 ratio.

CONCLUSION

OC might be a useful marker for the evaluation of immune status in patients with HIV/AIDS.

Proteomic analysis of serum proteins from HIV/AIDS patients with Talaromyces marneffei infection by TMT labeling-based quantitative proteomics

BACKGROUND

Talaromyces marneffei (TM) is an emerging pathogenic fungus that can cause a fatal systemic mycosis in patients infected with human immunodeficiency virus (HIV). Although global awareness regarding HIV/TM coinfection is increasing little is known about the mechanism that mediates the rapid progression to HIV/AIDS disease in coinfected individuals. The aim of this study was to analyze the serum proteome of HIV/TM coinfected patients and to identify the associated protein biomarkers for TM in patients with HIV/AIDS.

METHODS

We systematically used multiplexed isobaric tandem mass tag labeling combined with liquid chromatography mass spectrometry (LC-MS/MS) to screen for differentially expressed proteins in the serum samples from HIV/TM-coinfected patients.

RESULTS

Of a total data set that included 1099 identified proteins, approximately 86% of the identified proteins were quantified. Among them, 123 proteins were at least 1.5-fold up-or downregulated in the serum between HIV/TM-coinfected and HIV-mono-infected patients. Furthermore, our results indicate that two selected proteins (IL1RL1 and THBS1) are potential biomarkers for distinguishing HIV/TM-coinfected patients.

CONCLUSIONS

This is the first report to provide a global proteomic profile of serum samples from HIV/TM-coinfected patients. Our data provide insights into the proteins that are involved as host response factors during infection. These data shed new light on the molecular mechanisms that are dysregulated and contribute to the pathogenesis of HIV/TM coinfection. IL1RL1 and THBS1 are promising diagnostic markers for HIV/TM-coinfected patients although further large-scale studies are needed. Thus, quantitative proteomic analysis revealed molecular differences between the HIV/TM-coinfected and HIV-mono-infected individuals, and might provide fundamental information for further detailed investigations.

Genetic Diversity Among Candida albicans Isolated from Humans and Cattle with Respiratory Distress in Egypt

As human populaces develop, they are progressively squeezed into higher living densities. The same is true for horticulture and animals expected to bolster these communities. Despite the high potential for zoonotic transmission, connections among humans and cattle have been understudied; however, Candida albicans remains the most important medical mycosis. The genesis of the mycobiome can vary, and interactions between humans and cattle are progressively being perceived as a key interface for disease transmission. αINT1 is a unique gene from Candida albicans; hence, it has been used for detection as well as intraspecific and interspecific phylogenetic analysis of C. albicans collected from human patients and cattle with pulmonary distress in urban-rural populations. A total of 1,921 specimens were examined by direct microscopy and culture to recover yeast associated with human infection. Identification was performed by micromorphology using an API 20C AUX system. The fungal species identified in bovine nasal specimens were Alternaria species (15%), Penicillium species, and C. albicans (6.7%). Other fungal species, such as Aspergillus niger, Torulopsis species, Mucor species (5%), Aspergillus flavus, Fusarium species, Trichosporon species (3.3%), C. rugosa, C. tropical, and Saccharomyces species (1.7%), were also isolated. In human sputum specimens, C. albicans (20%) and C. parapsilosis (2.7%) were the only reported yeast species in our samples. The four identified C. albicans species (two human and two cattle) were subjected to αINT1 gene sequence analysis, which confirmed major phylogenetic relationships among human and cattle isolates. This finding highlights the public health importance of bovines as a potential source for C. albicans zoonotic transmission to humans in an urban-rural community. Additionally, the close relationship between circulating C. albicans strains recorded in Egypt and the United States indicates the possible cross-species transmission of C. albicans between imported foreign and native cattle breeds.

Novel Mechanism behind the Immunopathogenesis of Vulvovaginal Candidiasis: "Neutrophil Anergy"

For over 3 decades, investigators have studied the pathogenesis of vulvovaginal candidiasis (VVC) and recurrent VVC (RVVC) through clinical studies and animal models. While there was considerable consensus that susceptibility was not associated with any apparent deficiencies in adaptive immunity, protective immune mechanisms and the role of innate immunity remained elusive. It was not until an innovative live-challenge design was conducted in women that a fuller understanding of the natural history of infection/disease was achieved. These studies revealed that symptomatic infection is associated with recruitment of polymorphonuclear neutrophils (PMNs) into the vaginal lumen. Subsequent studies in the established mouse model demonstrated that infiltrating PMNs were incapable of reducing the fungal burden, which supported the hypothesis that VVC/RVVC was an immunopathology, whereby Candida and the host response drive symptomatic disease. Further studies in mice revealed the requirement for C. albicans hyphae and identified pattern recognition receptors (PRRs) and proinflammatory mediators responsible for the PMN response, all of which are critical pieces of the immunopathogenesis. However, a mechanism explaining PMN dysfunction at the vaginal mucosa remained an enigma. Ultimately, by employing mouse strains resistant or susceptible to chronic VVC, it was determined that heparan sulfate (HS) in the vaginal environment of susceptible mice serves as a competitive ligand for Mac-1 on PMNs, which effectively renders the PMNs incapable of binding to Candida to initiate killing. Hence, the outcome of symptomatic VVC/RVVC is postulated to be dependent on a PMN-mediated immunopathogenic response involving HS that effectively places the neutrophils in a state of functional anergy.

Clinico-mycological analysis and antifungal resistance pattern in human immunodeficiency virus-associated candidiasis: An Indian perspective

Objectives:

Candidiasis is a common human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome-associated opportunistic mycoses. The present study ascertained the species spectrum of Candida strains recovered from different clinical samples from symptomatic HIV-positive individuals and determined the antifungal susceptibility profile of the isolates.

Materials and Methods:

A variety of specimens were collected from 234 symptomatic HIV seropositive individuals depending on their clinical manifestations and subjected to direct microscopic examination. Blood samples were inoculated in biphasic blood culture medium and all other specimens on Sabouraud dextrose agar with chloramphenicol and incubated at 35°C–37°C. Species identification of the recovered Candida isolates was attempted on the basis of germ tube production, micromorphology on corn meal agar, color and morphology on HiCrome Candida Differential agar, and carbohydrate fermentation and assimilation tests. Susceptibility testing of the isolates was performed employing the VITEK 2 system.

Results:

A total of 167 Candida isolates were obtained; Candida albicans (136), Candida tropicalis (13), Candida krusei (8), Candida parapsilosis (5), Candida glabrata (4), and Candida kefyr (1). Fluconazole resistance was more frequent among nonalbicans species, and significantly higher 5-fluorocytosine resistance compared to C. albicans was also observed. Eight Candida strains (six C. krusei, one C. kefyr, and one C. albicans) were multidrug resistant.

Conclusion:

Although C. albicans continues to be the leading etiological agent of candidiasis, the incidence of nonalbicans species among HIV-positive Indian individuals is rising. Antifungal resistance was higher among nonalbicans Candida species. Another issue of therapeutic concern is the possible emergence of multidrug-resistant Candida strains among these patients.

The synthetic killer peptide KP impairs Candida albicans biofilm in vitro

Candida albicans is a commensal organism, commonly inhabiting mucosal surfaces of healthy individuals, as a part of the resident microbiota. However, in susceptible hosts, especially hospitalized and/or immunocompromised patients, it may cause a wide range of infections. The presence of abiotic substrates, such as central venous or urinary catheters, provides an additional niche for Candida attachment and persistence, particularly via biofilm development. Furthermore, Candida biofilm is poorly susceptible to most antifungals, including azoles. Here we investigated the effects of a synthetic killer peptide (KP), known to be active in vitro, ex vivo and/or in vivo against different pathogens, on C. albicans biofilm. Together with a scrambled peptide used as a negative control, KP was tested against Candida biofilm at different stages of development. A reference strain, two fluconazole-resistant and two fluconazole-susceptible C. albicans clinical isolates were used. KP-induced C. albicans oxidative stress response and membrane permeability were also analysed. Moreover, the effect of KP on transcriptional profiles of C. albicans genes involved in different stages of biofilm development, such as cell adhesion, hyphal development and extracellular matrix production, was evaluated. Our results clearly show that the treatment with KP strongly affected the capacity of C. albicans to form biofilm and significantly impairs preformed mature biofilm. KP treatment resulted in an increase in C. albicans oxidative stress response and membrane permeability; also, biofilm-related genes expression was significantly reduced. Comparable inhibitory effects were observed in all the strains employed, irrespective of their resistance or susceptibility to fluconazole. Finally, KP-mediated inhibitory effects were observed also against a catheter-associated C. albicans biofilm. This study provides the first evidence on the KP effectiveness against C. albicans biofilm, suggesting that KP may be considered as a potential novel tool for treatment and prevention of biofilm-related C. albicans infections.

Oral mucositis caused by Candida glabrata biofilms: failure of the concomitant use of fluconazole and ascorbic acid

OBJECTIVES

Candida glabrata is becoming one of the most prevalent pathogenic yeasts in cases of oral diseases. Mucositis is an recurrent oral infection in immunocompromised patients, and the actual guidelines recommend the use of fluconazole (Flu) for many cases. However, the azole resistance by C. glabrata is renowned, causing a reduced therapeutic response, especially when it occurs in biofilms. In this study, we performed an in vitro evaluation of an alternative pharmacotherapy for C. glabrata biofilm infections, combining ascorbic acid (AA) with Flu. AA is recognized for degrading β-glucans, an important compound of the biofilm matrices, which prevent drug diffusion.

MATERIALS AND METHODS

Routine clinical 30 or 40 mg/l doses of Flu were applied to C. glabrata biofilms simultaneously with 200 or 300 mg/l of AA.

RESULTS

The results showed that this combination effectively promoted the degradation of the biofilm network, but unfortunately, also stimulated the growth of the yeasts population due to release of several glucose monomers during β-glucans hydrolysis.

DISCUSSION

AA lead to the hydrolysis of the β-glucans of the matrix, liberating glucose molecules which are used as carbon souce by the yeasts, thus suppressing the desired antifungal effect of the drug combination with Flu.

CONCLUSIONS

Unlike to what happens in treatment of bacterial infection, AA should not be used together with Flu in the treating oral mucositis caused by Candida.

Efficacy of nystatin for the treatment of oral candidiasis: a systematic review and meta-analysis

Objective

To systematically review and assess the efficacy, different treatment protocols (formulation, dosage, and duration), and safety of nystatin for treating oral candidiasis.

Methods

Four electronic databases were searched for trials published in English till July 1, 2015. Randomized controlled trials comparing nystatin with other antifungal therapies or a placebo were included. Clinical and/or mycological cure was the outcome evaluation. A meta-analysis or descriptive study on the efficacy, treatment protocols, and safety of nystatin was conducted.

Results

The meta-analysis showed that nystatin pastille was significantly superior to placebo in treating denture stomatitis. Nystatin suspension was not superior to fluconazole in treating oral candidiasis in infants, children, or HIV/AIDS patients. The descriptive investigations showed that administration of nystatin suspension and pastilles in combination for 2 weeks might achieve a higher clinical and mycological cure rate, and using the nystatin pastilles alone might have a higher mycological cure rate, when compared with using nystatin suspensions alone. Nystatin pastilles at a dose of 400,000 IU resulted in a significantly higher mycological cure rate than that administrated at a dose of 200,000 IU. Furthermore, treatment with nystatin pastilles for 4 weeks seemed to have better clinical efficacy than treatment for 2 weeks. Descriptive safety assessment showed that poor taste and gastrointestinal adverse reaction are the most common adverse effects of nystatin.

Conclusion

Nystatin pastille was significantly superior to placebo in treating denture stomatitis, while nystatin suspension was not superior to fluconazole in treating oral candidiasis in infants, children, or HIV/AIDS patients. Indirect evidence from a descriptive study demonstrated that administration of nystatin pastille alone or pastille and suspension in combination is more effective than that of suspension alone; prolonged treatment duration for up to 4 weeks can increase the efficacy of nystatin. More well designed and high quality randomized control studies are needed to confirm these findings.

Epithelial discrimination of commensal and pathogenic Candida albicans

All mucosal surfaces are lined by epithelial cells and are colonised by opportunistic microbes. In health, these opportunistic microbes remain commensal and are tolerated by the immune system. However, when the correct environmental conditions arise, these microbes can become pathogenic and need to be controlled or cleared by the immune system to prevent disease. The mechanisms that enable epithelial cells to initiate the 'danger' signals activated specifically by pathogenic microbes are critical to mucosal defence and homeostasis but are not well understood. Deciphering these mechanisms will provide essential understanding to how mucosal tissues maintain health and activate immunity, as well as how pathogens promote disease. This review focuses on the interaction of the human fungal pathogen Candida albicans with epithelial cells and the epithelial mechanisms that enable mucosal tissues to discriminate between the commensal and pathogenic state of this medically important fungus.

Rapid detection of Candida species in bronchoalveolar lavage fluid from patients with pulmonary symptoms

Candida species, especially C. albicans, are commensals on human mucosal surfaces, but are increasingly becoming one of the important invasive pathogens as seen by a rise in its prevalence in immunocompromised patients and in antibiotic consumption. Thus, an accurate identification of Candida species in patients with pulmonary symptoms can provide important information for effective treatment. A total of 75 clinical isolates of Candida species were obtained from the bronchoalveolar lavage fluid of both immunocompromised and immunocompetent patients with pulmonary symptoms. Candida cultures were identified based on nuclear ribosomal Internal Transcribed Spacer (ITS1-ITS2 rDNA) sequence analysis by polymerase chain reaction–restriction fragment length polymorphisms (PCR-RFLP). Molecular identification indicated that the isolates belonged predominantly to C. albicans (52%), followed by C. tropicalis (24%), C. glabrata (14.7%), C. krusei (5.3%), C. parapsilosis (1.3%), C. kefyr (1.3%) and C. guilliermondii (1.3%). Given the increasing complexity of disease profiles and their management regimens in diverse patients, rapid and accurate identification of Candida species can lead to timely and appropriate antifungal therapy.

Spectrum and the In Vitro Antifungal Susceptibility Pattern of Yeast Isolates in Ethiopian HIV Patients with Oropharyngeal Candidiasis

Background. In Ethiopia, little is known regarding the distribution and the in vitro antifungal susceptibility profile of yeasts. Objective. This study was undertaken to determine the spectrum and the in vitro antifungal susceptibility pattern of yeasts isolated from HIV infected patients with OPC. Method. Oral pharyngeal swabs taken from oral lesions of study subjects were inoculated onto Sabouraud Dextrose Agar. Yeasts were identified by employing conventional test procedures and the susceptibility of yeasts to antifungal agents was evaluated by disk diffusion assay method. Result. One hundred and fifty-five yeast isolates were recovered of which 91 isolates were from patients that were not under HAART and 64 were from patients that were under HAART. C. albicans was the most frequently isolated species followed by C. glabrata, C. tropicalis, C. krusei, C. kefyr, Cryptococcus laurentii, and Rhodotorula species. Irrespective of yeasts isolated and identified, 5.8%, 5.8%, 12.3%, 8.4%, 0.6%, and 1.3% of the isolates were resistant to amphotericin B, clotrimazole, fluconazole, ketoconazole, miconazole, and nystatin, respectively. Conclusion. Yeast colonization rate of 69.2% and 31% resistance to six antifungal agents was documented. These highlight the need for nationwide study on the epidemiology of OPC and resistance to antifungal drugs.

Moonlight-like proteins of the cell wall protect sessile cells of Candida from oxidative stress

Biofilms of Candida species are associated with high morbidity and hospital mortality. Candida forms biofilms by adhering to human host epithelium through cell wall proteins (CWP) and simultaneously neutralizing the reactive oxygen species (ROS) produced during the respiratory burst by phagocytic cells. The purpose of this paper is to identify the CWP of Candida albicans, Candida glabrata, Candida krusei and Candida parapsilosis expressed after exposure to different concentrations of H2O2 using a proteomic approach. CWP obtained from sessile cells, both treated and untreated with the oxidizing agent, were resolved by one and two-dimensional (2D-PAGE) gels and identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Some of these proteins were identified and found to correspond to moonlighting CWP such as: (i) glycolytic enzymes, (ii) heat shock, (iii) OSR proteins, (iv) general metabolic enzymes and (v) highly conserved proteins, which are up- or down-regulated in the presence or absence of ROS. We also found that the expression of these CWP is different for each Candida species. Moreover, RT-PCR assays allowed us to demonstrate that transcription of the gene coding for Eno1, one of the moonlight-like CWP identified in response to the oxidant agent, is differentially regulated. To our knowledge this is the first demonstration that, in response to oxidative stress, each species of Candida, differentially regulates the expression of moonlighting CWP, which may protect the organism from the ROS generated during phagocytosis. Presumptively, these proteins allow the pathogen to adhere and form a biofilm, and eventually cause invasive candidiasis in the human host. We propose that, in addition to the antioxidant mechanisms present in Candida, the moonlighting CWP also confer protection to these pathogens from oxidative stress.

Clinical isolates of Candida albicans, Candida tropicalis, and Candida krusei have different susceptibilities to Co(II) and Cu(II) complexes of 1,10-phenanthroline

The minimal inhibitory concentrations (MICs) of copper and cobalt based dimeric pyrophosphate complexes with capping 1,10-phenanthroline groups on clinical isolates of C. albicans (28 isolates), C. krusei (20 isolates) and C. tropicalis (20 isolates) are reported. C. albicans was inhibited by the cobalt complex better than by the copper complex, while C. krusei demonstrated the opposite results. C. tropicalis showed similar sensitivities to both metals in terms of calculated MIC50 values but was more sensitive to cobalt when MIC90 values were noted. Knockout strains of C. albicans that had the copper efflux protein P-type ATPase (CRP1), the copper binding metallothionein CUP1 or both CRP1/CUP1 removed clearly demonstrate that the origins of copper resistant in C. albicans lies primarily in the P-type ATPase, with the MT playing an important secondary role in the absence of the efflux protein. This study suggests that certain strains of Candida have evolved to protect against particular metal ions and that in the case of C. albicans, a primary invasive fungal species, cobalt may be a good starting-point for new therapeutic development.

Detection and quantification of fluconazole within Candida glabrata biofilms

Candida infections are often associated with biofilms and consequent high resistance to most common drugs (e.g. azoles). These resistance mechanisms are not only associated with the biofilm yeast physiology, but also with the presence of a diffusional barrier imposed by the biofilm matrix; however, the real biochemical role of the biofilm components remains very unclear. So, in order to further clarify this issue, we intend to determine, for the first time, fluconazole in biofilms within both supernatants and matrices. Candida biofilms were formed in the presence of fluconazole, and it was recovered from both supernatant and matrix cell-free fractions. Then, high-pressure liquid chromatography was used to identify and quantify the amount of drug that was present in the two fractions. Moreover, this study also showed that the presence of fluconazole in both fractions indicated that the drug administrated did not completely reach the cells, so this phenomena can easily be associated with lower biofilm susceptibility, since the drug administered did not completely reach the cells.

Coriandrum sativum L. (Coriander) essential oil: antifungal activity and mode of action on Candida spp., and molecular targets affected in human whole-genome expression

Oral candidiasis is an opportunistic fungal infection of the oral cavity with increasingly worldwide prevalence and incidence rates. Novel specifically-targeted strategies to manage this ailment have been proposed using essential oils (EO) known to have antifungal properties. In this study, we aim to investigate the antifungal activity and mode of action of the EO from Coriandrum sativum L. (coriander) leaves on Candida spp. In addition, we detected the molecular targets affected in whole-genome expression in human cells. The EO phytochemical profile indicates monoterpenes and sesquiterpenes as major components, which are likely to negatively impact the viability of yeast cells. There seems to be a synergistic activity of the EO chemical compounds as their isolation into fractions led to a decreased antimicrobial effect. C. sativum EO may bind to membrane ergosterol, increasing ionic permeability and causing membrane damage leading to cell death, but it does not act on cell wall biosynthesis-related pathways. This mode of action is illustrated by photomicrographs showing disruption in biofilm integrity caused by the EO at varied concentrations. The EO also inhibited Candida biofilm adherence to a polystyrene substrate at low concentrations, and decreased the proteolytic activity of Candida albicans at minimum inhibitory concentration. Finally, the EO and its selected active fraction had low cytotoxicity on human cells, with putative mechanisms affecting gene expression in pathways involving chemokines and MAP-kinase (proliferation/apoptosis), as well as adhesion proteins. These findings highlight the potential antifungal activity of the EO from C. sativum leaves and suggest avenues for future translational toxicological research.

Effects of fluconazole on Candida glabrata biofilms and its relationship with ABC transporter gene expression

Candida glabrata has emerged as the second most prevalent fungal pathogen and its ability to form biofilms has been considered one of the most important virulence factors, since biofilms present a high tolerance to antifungal agents used in fungal infection treatment. The mechanisms of biofilm tolerance to antifungal agents remain poorly understood. Thus, the aim of this study was to evaluate the effects of fluconazole (FLU) on the formation and control of C. glabrata biofilms and its relation with the expression of genes encoding for ABC transporters, CDR1, SNQ2, and PDR1. For that, minimal inhibitory concentration values for seven C. glabrata strains were determined and the effect of FLU against C. glabrata biofilms was evaluated by total biomass quantification and viable cell enumeration. Matrices from biofilms were analyzed in terms of protein, carbohydrate and DNA content. ABC transporter gene expression was analyzed for quantitative real-time PCR. In addition to the high amounts of proteins and carbohydrates detected in the extracellular matrices in the presence of FLU, this work showed that the overexpression of efflux pumps is a possible mechanism of biofilm tolerance to FLU and this phenomenon alters the structure of C. glabrata biofilms by creating cell clusters.

Biofilm-forming ability and adherence to poly-(methyl-methacrylate) acrylic resin materials of oral Candida albicans strains isolated from HIV positive subjects

PURPOSE

This study evaluated the adhesion to acrylic resin specimens and biofilm formation capability of Candida albicans strains isolated from HIV positive subjects' oral rinse solutions.

MATERIALS AND METHODS

The material tested was a heat-cured acrylic resin (Acron Duo). Using the adhesion and crystal violet assays, 14 oral Candida albicans isolated from HIV-positive subjects and 2 references Candida strains (C. albicans ATCC 90028 and C. albicans ATCC 90128) were compared for their biofilm production and adhesion properties to acrylic surfaces in vitro.

RESULTS

There were no significant differences in adhesion (P=.52) and biofilm formation assays (P=.42) by statistical analysis with Mann-Whitney test.

CONCLUSION

Denture stomatitis and increased prevalence of candidal carriage in HIV infected patients is unlikely to be related to the biofilm formation and adhesion abilities of C. albicans to acrylic resin materials.

Candida glabrata: a review of its features and resistance

Candida species belong to the normal microbiota of the oral cavity and gastrointestinal and vaginal tracts, and are responsible for several clinical manifestations, from mucocutaneous overgrowth to bloodstream infections. Once believed to be non-pathogenic, Candida glabrata was rapidly blamable for many human diseases. Year after year, these pathological circumstances are more recurrent and problematic to treat, especially when patients reveal any level of immunosuppression. These difficulties arise from the capacity of C. glabrata to form biofilms and also from its high resistance to traditional antifungal therapies. Thus, this review intends to present an excerpt of the biology, epidemiology, and pathology of C. glabrata, and detail an approach to its resistance mechanisms based on studies carried out up to the present.

Proteomic Analysis of Intracellular and Membrane Proteins From Voriconazole-Resistant Candida glabrata

Objectives

The proteomic analysis of voriconazole resistant Candida glabrata strain has not yet been investigated. In this study, differentially expressed proteins of intracellular and membrane fraction from voriconazole-susceptible, susceptible dose-dependent (S-DD), resistant C. glabrata strains were compared with each other and several proteins were identified.

Methods

The proteins of intracellular and membrane were isolated by disrupting cells with glass bead and centrifugation from voriconazole susceptible, S-DD, and resistant C. glabrata strains. The abundance of expressed proteins was compared using two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis and proteins showing continuous twofold or more increase or reduction of expression in resistant strains compared to susceptible and S-DD strain were analyzed by liquid chromatography/mass spectrometry-mass spectrometry method.

Results

Of 34 intracellular proteins, 15 proteins showed expression increase or reduction (twofold or more). The identified proteins included regulation, energy production, carbohydrate transport, amino acid transport, and various metabolism related proteins. The increase of expression of heat shock protein 70 was found. Among membrane proteins, 12, 31 proteins showed expression increase or decrease in the order of susceptible, S-DD, and resistant strains. This expression included carbohydrate metabolism, amino acid synthesis, and response to stress-related proteins. In membrane fractions, the change of expression of 10 heat shock proteins was observed, and 9 heat shock protein 70 (Hsp70) showed the reduction of expression.

Conclusion

The expression of Hsp70 protein in membrane fraction is related to voriconazole resistant C. glabrata strains.

Frequent detection of 'azole' resistant Candida species among late presenting AIDS patients in northwest Ethiopia

BACKGROUND

The chronic use of antifungal agents in the treatment of fungal infection in general and oropharyngeal candidiasis mainly in AIDS patient's leads to the selection of strain resistant to these therapies and a shift in the spectrum of Candida species. This study determines the species diversity and in vitro susceptibility of Candida isolates from late presenting AIDS patients in northwest Ethiopia.

METHODS

Two hundred and twenty one HIV/AIDS patients were assessed with a standardized evaluation form at enrolment. Oral rinses were cultured on CHROMagar plates at 37°C for 48 hours and Candida species identification were made following standard microbiological techniques. In vitro drug susceptibility tests were made using broth microdilution method.

RESULTS

The colonization rate of Candida species was found to be 82.3% (177/215). C. albicans was the predominant species isolated from 139 (81%) patients but there was a diversity of other species. C. glabrata was the most frequent non-albicans species isolated in 22.5% (40/177) of the patients followed by C. tropicalis 14.1% (27/177), C. krusei 5.6% (10) and other unidentifiable Candida species 4% (7/177). Recurrent episodes of oropharyngeal candidiasis and previous exposure to antifungal drugs were found to be predisposing factors for colonization by non-albicans species. Irrespective of the Candida species identified 12.2% (11/90), 7.7% (7/90) and 4.7% (4) of the isolates were resistant to fluconazole, ketoconazole and itraconazole, respectively. In contrast, resistance to micafungin, amphotericin B and 5-Fluorocytosine was infrequent.

CONCLUSION

HIV/AIDS patients are orally colonized by single or multiple albicans and non- albicans Candida species that are frequently resistant to azoles and occasionally to amphotericin B, 5-Fluorocytosine and micafungin. These highlight the need for national surveillance for examining Candida epidemiology and resistance to antifungal drugs.

Candida species: new insights into biofilm formation

Biofilms of Candida albicans, Candida parapsilosis, Candida glabrata and Candida tropicalis are associated with high indices of hospital morbidity and mortality. Major factors involved in the formation and growth of Candida biofilms are the chemical composition of the medical implant and the cell wall adhesins responsible for mediating Candida-Candida, Candida-human host cell and Candida-medical device adhesion. Strategies for elucidating the mechanisms that regulate the formation of Candida biofilms combine tools from biology, chemistry, nanoscience, material science and physics. This review proposes the use of new technologies, such as synchrotron radiation, to study the mechanisms of biofilm formation. In the future, this information is expected to facilitate the design of new materials and antifungal compounds that can eradicate nosocomial Candida infections due to biofilm formation on medical implants. This will reduce dissemination of candidiasis and hopefully improve the quality of life of patients.

Staphylococcus spp., Enterobacteriaceae and Pseudomonadaceae oral isolates from Brazilian HIV-positive patients. Correlation with CD4 cell counts and viral load

The aim was to evaluate the presence of Staphylococcus spp., Enterobacteriaceae and Pseudomonadaceae in the oral cavities of HIV-positive patients. Forty-five individuals diagnosed as HIV-positive by ELISA and Western-blot, and under anti-retroviral therapy for at least 1 year, were included in the study. The control group constituted 45 systemically healthy individuals matched to the HIV patients to gender, age and oral conditions. Oral rinses were collected and isolates were identified by API system. Counts of microorganisms from HIV and control groups were compared statistically by a Mann-Whitney test (α=5%). The percentages of individuals positive for staphylococci were similar between the groups (p=0.764), whereas for Gram-negative rods, a higher percentage was observed amongst HIV-positive (p=0.001). There was no difference in Staphylococcus counts between HIV and control groups (p=0.1008). Counts were lower in the oral cavities of patients with low viral load (p=0.021), and no difference was observed in relation to CD4 counts (p=0.929). Staphylococcus aureus was the most frequently isolated species in HIV group, and Staphylococcus epidermidis was the prevalent species in the control group. Significantly higher numbers of enteric bacteria and pseudomonas were detected in the oral cavities of the HIV group than in the control (p=0.0001). Enterobacter cloacae was the most frequently isolated species in both groups. Counts of enteric bacteria and pseudomonas were significantly lower in patients with low CD4 counts (p=0.011); however, there was no difference relating to viral load. It may be concluded that HIV group showed greater species diversity and a higher prevalence of Enterobacteriaceae/Pseudomonadaceae.

Biofilms of non-Candida albicans Candida species: quantification, structure and matrix composition

Most cases of candidiasis have been attributed to C. albicans, but recently, non- Candida albicans Candida (NCAC) species have been identified as common pathogens. The ability of Candida species to form biofilms has important clinical repercussions due to their increased resistance to antifungal therapy and the ability of yeast cells within the biofilms to withstand host immune defenses. Given this clinical importance of the biofilm growth form, the aim of this study was to characterize biofilms produced by three NCAC species, namely C. parapsilosis, C. tropicalis and C. glabrata. The biofilm forming ability of clinical isolates of C. parapsilosis, C. tropicalis and C. glabrata recovered from different sources, was evaluated by crystal violet staining. The structure and morphological characteristics of the biofilms were also assessed by scanning electron microscopy and the biofilm matrix composition analyzed for protein and carbohydrate content. All NCAC species were able to form biofilms although these were less extensive for C. glabrata compared with C. parapsilosis and C. tropicalis. It was evident that C. parapsilosis biofilm production was highly strain dependent, a feature not evident with C. glabrata and C. tropicalis. Scanning electron microscopy revealed structural differences for biofilms with respect to cell morphology and spatial arrangement. Candida parapsilosis biofilm matrices had large amounts of carbohydrate with less protein. Conversely, matrices extracted from C. tropicalis biofilms had low amounts of carbohydrate and protein. Interestingly, C. glabrata biofilm matrix was high in both protein and carbohydrate content. The present work demonstrates that biofilm forming ability, structure and matrix composition are highly species dependent with additional strain variability occurring with C. parapsilosis.

Antifungal activity of alpha-mangostin against Candida albicans

This study was conducted to examine the activity of alpha-mangostin against Candida albicans, the most important microorganism implicated in oral candidiasis. Its activity was compared to Clotrimazole and Nystatin. Results showed that alpha-mangostin was effective against C. albicans, the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were 1,000 and 2,000 microg/ml, respectively. The C. albicans killing activity of alpha-mangostin was more effective than Clotrimazole and Nystatin. The cytotoxicity of alpha-mangostin was determined and it was found that alpha-mangostin at 4,000 microg/ml was not toxic to human gingival fibroblast for 480 min. The strong antifungal activity and low toxicity of alpha-mangostin make it a promising agent for treatment of oral candidiasis.

Homothallic and heterothallic mating in the opportunistic pathogen Candida albicans

Candida albicans is the most common fungal pathogen in humans, causing both debilitating mucosal infections and potentially life-threatening systemic infections. Until recently, C. albicans was thought to be strictly asexual, existing only as an obligate diploid. A cryptic mating cycle has since been uncovered in which diploid a and alpha cells undergo efficient cell and nuclear fusion, resulting in tetraploid a/alpha mating products. Whereas mating between a and alpha cells has been established (heterothallism), we report here two pathways for same-sex mating (homothallism) in C. albicans. First, unisexual populations of a cells were found to undergo autocrine pheromone signalling and same-sex mating in the absence of the Bar1 protease. In both C. albicans and Saccharomyces cerevisiae, Bar1 is produced by a cells and inactivates mating pheromone alpha, typically secreted by alpha cells. C. albicans Deltabar1 a cells were shown to secrete both a and alpha mating pheromones; alpha-pheromone activated self-mating in these cells in a process dependent on Ste2, the receptor for alpha-pheromone. In addition, pheromone production by alpha cells was found to promote same-sex mating between wild-type a cells. These results establish that homothallic mating can occur in C. albicans, revealing the potential for genetic exchange even within unisexual populations of the organism. Furthermore, Bar1 protease has an unexpected but pivotal role in determining whether sexual reproduction can potentially be homothallic or is exclusively heterothallic. These findings also have implications for the mode of sexual reproduction in related species that propagate unisexually, and indicate a role for specialized sexual cycles in the survival and adaptation of pathogenic fungi.

Prevalência e fatores associados às manifestações bucais em pacientes HIV positivos atendidos em cidade sul-brasileira

O objetivo deste estudo foi avaliar a prevalência de lesões bucais entre pacientes HIV positivos e identificar fatores associados a tais lesões. Foi realizado estudo transversal que coletou dados mediante entrevista, exame clínico e consulta aos prontuários médicos de pacientes adultos atendidos no Serviço de HIV-AIDS do Hospital Universitário da Universidade Federal do Rio Grande, Rio Grande do Sul, Brasil, sendo considerados fatores sócio-demográficos, imunológicos e terapêuticos. Foi utilizada a regressão de Poisson num modelo hierárquico de análise. Entre abril de 2006 a janeiro de 2007 foram observados 300 pacientes, sendo 51% do sexo masculino e média de idade de 40 anos; 39% apresentaram lesões bucais, sendo a candidíase a mais freqüente (59,1%), seguida de leucoplasia pilosa (19,5%). As mulheres apresentaram um risco menor, com observância de uma associação inversa com o CD4. Houve um risco maior entre aqueles pacientes com menor escolaridade, menor renda, tabagistas, dependentes do álcool, com maior tempo de infecção pelo HIV e carga viral mais elevada. Os dados confirmaram a elevada prevalência das manifestações bucais oportunistas e evidenciaram a sua relação com a situação social, assim como sua relação com determinados hábitos e costumes passíveis de modificação.

Biofilm lifestyle of Candida: a mini review

Candida is the major fungal pathogen of humans causing a variety of afflictions ranging from superficial mucosal diseases to deep seated mycoses. Biofilm formation is a major virulence factor in the pathogenicity of Candida, and Candida biofilms are difficult to eradicate especially because of their very high antifungal resistance. Consequently, research into the pathogenicity of Candida has focused on the prevention and management of biofilm development, their architecture, and antifungal resistance. Although studies have shed some light, molecular mechanisms that govern biofilm formation and pathogenicity still await full clarification. This review outlines the key features of what is currently known of Candida biofilm development, regulation and antifungal resistance and, their proteomics.

Species distribution and in vitro antifungal susceptibility of oral yeast isolates from Tanzanian HIV-infected patients with primary and recurrent oropharyngeal candidiasis

Background

In Tanzania, little is known on the species distribution and antifungal susceptibility profiles of yeast isolates from HIV-infected patients with primary and recurrent oropharyngeal candidiasis.

Methods

A total of 296 clinical oral yeasts were isolated from 292 HIV-infected patients with oropharyngeal candidiasis at the Muhimbili National Hospital, Dar es Salaam, Tanzania. Identification of the yeasts was performed using standard phenotypic methods. Antifungal susceptibility to fluconazole, itraconazole, miconazole, clotrimazole, amphotericin B and nystatin was assessed using a broth microdilution format according to the guidelines of the Clinical and Laboratory Standard Institute (CLSI; M27-A2).

Results

Candida albicans was the most frequently isolated species from 250 (84.5%) patients followed by C. glabrata from 20 (6.8%) patients, and C. krusei from 10 (3.4%) patients. There was no observed significant difference in species distribution between patients with primary and recurrent oropharyngeal candidiasis, but isolates cultured from patients previously treated were significantly less susceptible to the azole compounds compared to those cultured from antifungal naïve patients.

Conclusion

C. albicans was the most frequently isolated species from patients with oropharyngeal candidiasis. Oral yeast isolates from Tanzania had high level susceptibility to the antifungal agents tested. Recurrent oropharyngeal candidiasis and previous antifungal therapy significantly correlated with reduced susceptibility to azoles antifungal agents.

Candida albicans Sun41p, a putative glycosidase, is involved in morphogenesis, cell wall biogenesis, and biofilm formation

The SUN gene family has been defined in Saccharomyces cerevisiae and comprises a fungus-specific family of proteins which show high similarity in their C-terminal domains. Genes of this family are involved in different cellular processes, like DNA replication, aging, mitochondrial biogenesis, and cytokinesis. In Candida albicans the SUN family comprises two genes, SUN41 and SIM1. We demonstrate that C. albicans mutants lacking SUN41 show similar defects as found for S. cerevisiae, including defects in cytokinesis. In addition, the SUN41 mutant showed a higher sensitivity towards the cell wall-disturbing agent Congo red, whereas no difference was observed in the presence of calcofluor white. Compared to the wild type, SUN41 deletion strains exhibited a defect in biofilm formation, a reduced adherence on a Caco-2 cell monolayer, and were unable to form hyphae on solid medium under the conditions tested. Interestingly, Sun41p was found to be secreted in the medium of cells growing as blastospores as well as those forming hyphae. Our results support a function of SUN41p as a glycosidase involved in cytokinesis, cell wall biogenesis, adhesion to host tissue, and biofilm formation, indicating an important role in the host-pathogen interaction.