Antifungal Drug Sensitivity Research Articles

Severe pneumonia with pleural effusion caused by co-infection of Paecilomyces variotii and Penicillium oxalicum in a diabetic patient

Background paecilomycesand Penicillium are considered as rare opportunistic pathogens in immunocompromised hosts, and pneumonia caused by Paecilomyces and Penicillium is rare. In this study, we present first case of severe pneumonia with pleural effusion caused by co-infection of Paecilomyces variotii (P. variotii) and Penicillium oxalicum (P. oxalicum) in a 66-year-old female with poorly controlled type 2 diabetes.Case presentationA 56-year-old woman patient presented to hospital for nausea, poor appetite, and vomiting for one day. On the second day of admission, blood culture and renal puncture fluid culture grew multidrug-resistant Escherichia coli (imipenem/cilastatin sensitive), and she received combination therapy with imipenem/cilastatin (1 g, every 8 h) and vancomycin (0.5 g, every 12 h). On the fourth day, she developed symptoms of respiratory failure. Pulmonary computed tomography (CT) showed an increase in pneumonia compared to before, with minor pleural effusion on both sides. Two fungi were isolated repeatedly from BALF culture, which were confirmed as P. variotii and P. oxalicum by Internal transcribed spacer (ITS) sequencing. Her pleural effusion was completely absorbed, pneumonia symptoms have significantly improved and discharged with receiving liposomal amphotericin B treatment for four weeks.ConclusionsIt is worth noting that clinicians and laboratory personnel should not simply consider Paecilomyces and Penicillium species as contaminants, especially in immunocompromised patients. Early fungal identification and antifungal drug sensitivity are crucial for clinical drug selection and patient prognosis.

Deciphering antifungal and antibiofilm mechanisms of isobavachalcone against Cryptococcus neoformans through RNA-seq and functional analyses

Cryptococcus neoformans has been designated as critical fungal pathogens by the World Health Organization, mainly due to limited treatment options and the prevalence of antifungal resistance. Consequently, the utilization of novel antifungal agents is crucial for the effective treatment of C. neoformans infections. This study exposed that the minimum inhibitory concentration (MIC) of isobavachalcone (IBC) against C. neoformans H99 was 8 µg/mL, and IBC dispersed 48-h mature biofilms by affecting cell viability at 16 µg/mL. The antifungal efficacy of IBC was further validated through microscopic observations using specific dyes and in vitro assays, which confirmed the disruption of cell wall/membrane integrity. RNA-Seq analysis was employed to decipher the effect of IBC on the C. neoformans H99 transcriptomic profiles. Real-time quantitative reverse transcription PCR (RT-qPCR) analysis was performed to validate the transcriptomic data and identify the differentially expressed genes. The results showed that IBC exhibited various mechanisms to impede the growth, biofilm formation, and virulence of C. neoformans H99 by modulating multiple dysregulated pathways related to cell wall/membrane, drug resistance, apoptosis, and mitochondrial homeostasis. The transcriptomic findings were corroborated by the antioxidant analyses, antifungal drug sensitivity, molecular docking, capsule, and melanin assays. In vivo antifungal activity analysis demonstrated that IBC extended the lifespan of C. neoformans-infected Caenorhabditis elegans. Overall, the current study unveiled that IBC targeted multiple pathways simultaneously to inhibit growth significantly, biofilm formation, and virulence, as well as to disperse mature biofilms of C. neoformans H99 and induce cell death.

Pan-Indian Clinical Registry of Invasive Fungal Infections Among Patients in the Intensive Care Unit: Protocol for a Multicentric Prospective Study.

Fungal infections are now a great public health threat, especially in those with underlying risk factors such as neutropenia, diabetes, high-dose steroid treatment, cancer chemotherapy, prolonged intensive care unit stay, and so on, which can lead to mycoses with higher mortality rates. The rates of these infections have been steadily increasing over the past 2 decades due to the increasing population of patients who are immunocompromised. However, the data regarding the exact burden of such infection are still not available from India. Therefore, this registry was initiated to collate systematic data on invasive fungal infections (IFIs) across the country. The primary aim of this study is to create a multicenter digital clinical registry and monitor trends of IFIs and emerging fungal diseases, as well as early signals of any potential fungal outbreak in any region. The registry will also capture information on the antifungal resistance patterns and the contribution of fungal infections on overall morbidity and inpatient mortality across various conditions. This multicenter, prospective, noninterventional observational study will be conducted by the Indian Council of Medical Research through a web-based data collection method from 8 Advanced Mycology Diagnostic and Research Centers across the country. Data on age, gender, clinical signs and symptoms, date of admission, date of discharge or death, diagnostic tests performed, identified pathogen details, antifungal susceptibility testing, outcome, and so on will be obtained from hospital records. Descriptive and multivariate statistical methods will be applied to investigate clinical manifestations, risk variables, and treatment outcomes. These Advanced Mycology Diagnostic and Research Centers are expected to find the hidden cases of fungal infections in the intensive care unit setting. The study will facilitate the enhancement of the precision of fungal infection diagnosis and prompt treatment modalities in response to antifungal drug sensitivity tests. This registry will improve our understanding of IFIs, support evidence-based clinical decision-making ability, and encourage public health policies and actions. Fungal diseases are a neglected public health problem. Fewer diagnostic facilities, scanty published data, and increased vulnerable patient groups make the situation worse. This is the first systematic clinical registry of IFIs in India. Data generated from this registry will increase our understanding related to the diagnosis, treatment, and prevention of fungal diseases in India by addressing pertinent gaps in mycology. This initiative will ensure a visible impact on public health in the country. DERR1-10.2196/54672.

A Clinico-mycological, Antifungal Drug Sensitivity and Therapeutic Study of Extensive Dermatophytosis in Coastal Andhra Pradesh.

In India, an increased prevalence of chronic, recurrent, and recalcitrant dermatophytosis is being observed. The present study assesses the clinico-mycological profile, antifungal drug sensitivity and therapeutic efficacy of various systemic antifungal drug regimens, in extensive dermatophytosis patients of coastal Andhra Pradesh. One hundred and fifty clinically diagnosed cases of extensive dermatophytosis affecting more than one body region were enrolled. Skin samples were taken for direct microscopy and fungal culture. Antifungal drug sensitivity testing was done with broth microdilution test. Therapeutic efficacy of systemic antifungal drug regimens was determined by randomly dividing the patients into 5 groups of 30 each. The most common clinical patterns observed were tinea corporis et cruris (62.7%) followed by extensive tinea corporis (11.3%). KOH and culture positivity were seen in 132 (88%) and 84 cases (56%) respectively. Trichophyton mentagrophytes was isolated in 78 cases (92.8%) followed by Microsporum gypseum in 6 patients (7.1%). The overall mean minimum inhibitory concentration values for itraconazole (0.04 μg/mL) were low when compared to griseofulvin (4.61 μg/mL) and terbinafine (6.9 μg/mL) (P < 0.05). Combination of itraconazole and griseofulvin achieved highest clinical and mycological cure rates (93.1%). Among patients receiving single drugs, itraconazole had higher cure rates (71.4%) compared to terbinafine (59.2%) and griseofulvin (53.8%) (P < 0.05). Trichophyton mentagrophytes has replaced Trichophyton rubrum as the predominant species causing dermatophytosis in Andhra Pradesh, presenting with a severe phenotype. Itraconazole was found to be the most effective drug both in vivo and in vitro. A combination of systemic drugs should be considered in cases of monotherapy failure and in recalcitrant dermatophytosis.

XÁC ĐỊNH MỨC ĐỘ NHẠY CẢM VỚI THUỐC KHÁNG NẤM CỦA CHỦNG NẤM ASPEGILLUS PHÂN LẬP ĐƯỢC Ở BỆNH NHÂN NHIỄM NẤM PHỔI XÂM LẤN TẠI BỆNH VIỆN BẠCH MAI TỪ THÁNG 7/2020-6/2021

Objectives: 1. Determination of the percentage of Aspergillus species isolated in patients with invasive lung fungal infections at Bach Mai Hospital from July 2020 to June 2021; 2. Determination of susceptibility to antifungal drugs of isolated pathogenic Aspergillus strains.. Method: We conducted a cross-sectional study. 97 Aspergillus strains isolated from patients diagnosed with invasive lung fungal infections at Bach Mai Hospital from July 2020 to June 2021. Result: Aspergillus species isolated in patients with invasive lung fungal infections were mainly Aspergillus fumigatus (92.8%), and Aspergillus flavus (7.2%). The susceptibility rate to Asspergillus fumigatus of Voriconazole was 98.9%, Itraconazole was 100% and Posaconazole was 100%. The sensitivity rate of Itraconazole, Voriconazole and Posaconazole to Aspergillus flavus is 100%. The rate of resistance to Amphotericin B of Aspergillus fumigatus was 94.4%, of Aspergillus flavus was 85.1%. Conclusion: Aspergillus strains isolated in patients with invasive lung fungal infections at Bach Mai Hospital were frequently encountered with Aspergillus fumigatus and Aspergillus flavus. All strains of Aspergillus spp. Both are sensitive to Itraconazole and Posaconazole. Rate of resistance to Amphotericin B of Aspergillus spp. is very high. Keywords: Aspergillus spp., antifungal drug sensitivity

Fungal keratitis: A review of clinical presentations, treatment strategies and outcomes

Infectious keratitis is a significant cause of corneal blindness worldwide. Although less prevalent in the developed world, cases of fungal keratitis account for almost half of all keratitis cases, occurring in the developing countries. These cases are one of the most refractory types of infectious keratitis and present various challenges to the treating physician such as delayed presentation, long waiting time for culture positivity, limited availability effective antifungal drugs, prolonged duration for response to therapy, a highly variable spectrum of anti-fungal drug sensitivity and a high recurrence rate following keratoplasty. The advent of rapid diagnostic tools, molecular methods, in vitro anti-fungal drug sensitivity testing, alternatives to natamycin, targeted drug delivery and most importantly the results of large randomized controlled trials have significantly improved our understanding and approach towards the diagnosis and management of cases with fungal keratitis.Overall, Aspergillus and Fusarium species are the most common causes ones of fungal keratitis. History of antecedent trauma is a significant predisposing factor. Corneal scrapings for microscopic evaluation and culture preparation, is the standard of care for establishing the diagnosis of fungal keratitis. Molecular identification of cultures offers accurate identification of fungal pathogens, especially the rare species. Natamycin is an approved first-line drug. Voriconazole is the best alternative, especially for non-fusarium cases. Management involves administration of drugs usually by a combination of various routes, the treatment regimen being individualized depending upon the response to therapy. Photodynamic therapy is a newer treatment modality, being tried for non-responsive cases, before resorting to a therapeutic graft.

Candida albicans ENT2 Contributes to Efficient Endocytosis, Cell Wall Integrity, Filamentation, and Virulence.

ABSTRACTEpsins play a pivotal role in the formation of endocytic vesicles and potentially provide a linkage between endocytic and other trafficking pathways. We identified a Candida albicans epsin, ENT2, that bears homology to the Saccharomyces cerevisiae early endocytosis genes ENT1 and ENT2 and studied its functions by a reverse genetic approach utilizing CRISPR-Cas9-mediated gene deletion. The C. albicans ent2Δ/Δ null mutant displayed cell wall defects and altered antifungal drug sensitivity. To define the role of C. albicans ENT2 in endocytosis, we performed assays with the lipophilic dye FM4-64 that revealed greatly reduced uptake in the ent2Δ/Δ mutant. Next, we showed that the C. albicans ent2Δ/Δ mutant was unable to form hyphae and biofilms. Assays for virulence properties in an in vitro keratinocyte infection model demonstrated reduced damage of mammalian adhesion zippers and host cell death from the ent2Δ/Δ mutant. We conclude that C. albicans ENT2 has a role in efficient endocytosis, a process that is required for maintaining cell wall integrity, hyphal formation, and virulence-defining traits.IMPORTANCE The opportunistic fungal pathogen Candida albicans is an important cause of invasive infections in hospitalized patients and a source of considerable morbidity and mortality. Despite its clinical importance, we still need to improve our ability to diagnose and treat this common pathogen. In order to support these advancements, a greater understanding of the biology of C. albicans is needed. In these studies, we are focused on the fundamental biological process of endocytosis, of which little is directly known in C. albicans. In addition to studying the function of a key gene in this process, we are examining the role of endocytosis in the virulence-related processes of filamentation, biofilm formation, and tissue invasion. These studies will provide greater insight into the role of endocytosis in causing invasive fungal infections.

Pleiotropy and epistasis within and between signaling pathways defines the genetic architecture of fungal virulence.

Cryptococcal disease is estimated to affect nearly a quarter of a million people annually. Environmental isolates of Cryptococcus deneoformans, which make up 15 to 30% of clinical infections in temperate climates such as Europe, vary in their pathogenicity, ranging from benign to hyper-virulent. Key traits that contribute to virulence, such as the production of the pigment melanin, an extracellular polysaccharide capsule, and the ability to grow at human body temperature have been identified, yet little is known about the genetic basis of variation in such traits. Here we investigate the genetic basis of melanization, capsule size, thermal tolerance, oxidative stress resistance, and antifungal drug sensitivity using quantitative trait locus (QTL) mapping in progeny derived from a cross between two divergent C. deneoformans strains. Using a “function-valued” QTL analysis framework that exploits both time-series information and growth differences across multiple environments, we identified QTL for each of these virulence traits and drug susceptibility. For three QTL we identified the underlying genes and nucleotide differences that govern variation in virulence traits. One of these genes, RIC8, which encodes a regulator of cAMP-PKA signaling, contributes to variation in four virulence traits: melanization, capsule size, thermal tolerance, and resistance to oxidative stress. Two major effect QTL for amphotericin B resistance map to the genes SSK1 and SSK2, which encode key components of the HOG pathway, a fungal-specific signal transduction network that orchestrates cellular responses to osmotic and other stresses. We also discovered complex epistatic interactions within and between genes in the HOG and cAMP-PKA pathways that regulate antifungal drug resistance and resistance to oxidative stress. Our findings advance the understanding of virulence traits among diverse lineages of Cryptococcus, and highlight the role of genetic variation in key stress-responsive signaling pathways as a major contributor to phenotypic variation.

Candidal Onychomycosis: Clinicoepidemiological Profile, Prevailing Strains, and Antifungal Susceptibility Pattern-A Study from a Tertiary Care Hospital.

Background:Despite an increasing trend of onychomycosis caused by Candida species in recent years, there is a scarcity of published data.Objective:To determine the epidemiological and clinical characteristics of Candida onychomycosis, to identify the prevalent, and perform in-vitro antifungal susceptibility testing (AFST) of the isolates.Methodology:A total of 506 consecutive patients with a clinical suspicion of onychomycosis were included in a cross-sectional clinical study. Nail scrapings and clippings were subjected to KOH examination and culture. Species identification and antifungal drug sensitivity testing were done for Candida isolates using Vitek 2YST Compact system using Vitek 2 cards.Results:Out of 384 (75.88%) culture-positive cases, dermatophytes were isolated in 58.08%, yeast in 26.30%, and NDM in 12.24%. Of the yeast, Candida albicans was isolated in 59.4% and non-albicans species in 40.59%. AFST showed that most of Candida species exhibited 100% susceptibility to most of the antifungal drugs tested, while intermediate resistance to fluconazole and flucytosine was seen in some non-albicans species (C. krusei, C. glabrata, and C. guilliermondii). Time taken for species identification was 14–18 h (average 15.5 h), while determination of minimum inhibitory concentration took 9–27 h (average 13 h).Conclusions:Our study showcases the present scenario of Candida distribution and the resistance patterns of various species afflicting the nail unit. Furthermore, our findings clearly indicate that the carriage of this pathogenic yeast is seen in both healthy individuals as well as with immunosuppression.

In vitro Evaluation of Some Herbal Compounds on Fungi Isolated from Clinical Cases in Animals and their Associated Environment

Background: Fungal infections are often difficult to cure in animals due to cost of treatment and emerging antifungal drug resistance. Herbal antifungals may be an alternate. Therefore, the objective of this study was to determine antifungal drug sensitivity pattern and activity of herbal antimicrobials on fungal isolates from clinical cases in animals and their associated environment. Methods and Findings: This study was conducted on 69 isolates comprised of yeasts (49) and moulds (20) isolated from clinical cases of animal (26) and environmental (22) samples and one reference strain for determining antifungal efficacy of common antimycotic drugs (amphotericin B, miconazole, nystatin, clotrimazole, itraconazole, ketconazole and fluconazole) and herbal antimicrobials viz., ajowan (Trachyspermum ammi) seed oil, betel (Piper betle) leaf oil, guggul (Commiphora mukul) oil, thyme (Thymus vulgaris) oil, marjoram (Origanum majorana) essential oil, Cinnamon (Cinnamomum verum) bark oil, holy basil (Ocimum sanctum) oil, citral, cinnamledehyde, carvacrol, lemongrass (Cymbopogon citrates) oil, sandalwood (Santalum album) oil, methanolic extract of Eupatorium odoratum leaves, Methanolic extract of Ageratum conizoides, essential oil of Zanthoxyllum rhetsa seed carp, agarwood (Aquilaria malaccensis) oil, and patchouli (Pogostemon cablin) essential oil amphotericin B (100 units), miconazole (10 µg), nystatin (100 units), clotrimazole (10 µg), itraconazole (10 µg), ketconazole (30 µg) and fluconazole (10 µg). Most of the yeast isolates except six from soil (2) and water (4) were sensitive to nystatin. Amphotericin B inhibited almost two third of the yeast isolates and miconazole was the most effective (75%) imidazoles followed by clotrimazole (38.8%), itraconazole (32.65%), fluconazole (18.4%) and ketoconazole (12.25%). Among herbals, thyme oil, carvacrol, cinnamon oil and cinnamaledehyde inhibited the growth of all the yeast isolates tested with MIC ranging from 0.001 mg to 1.2 mg mL-1. The next most effective herbal was holy basil oil (95.2%) followed by ajowan oil (87.75%), citral (87.75%) and lemongrass oil (77.75%). Lemongrass oil was equally antimycotic both on yeasts and moulds. The study revealed the promising antimycotic activity of herbs and prevalent antimycotic drug resistance among clinically important fungi in animals. Conclusion: The fungi associated with animal clinical infections and their environment were often resistant to commonly used antifungal drugs but some of the herbals as cinnamon oil, thyme oil, ajowan oil and lemongrass oil as well as their active components have shown potential antifungal activity and hope for the future drug development.

Biofilms Formed by Isolates from Recurrent Vulvovaginal Candidiasis Patients Are Heterogeneous and Insensitive to Fluconazole.

Vulvovaginal candidiasis (VVC) is a global health problem affecting ∼75% of women at least once in their lifetime. Here we examined the epidemiology of VVC in a patient cohort to identify the causative organisms associated with VVC. Biofilm-forming capacity and antifungal sensitivity profiles were also assessed. We report a shifting prevalence of Candida species with heterogeneous biofilm-forming capacity, which is associated with altered antifungal drug sensitivity.

Phenotypic switching inCandida tropicalis: association with modification of putative virulence attributes and antifungal drug sensitivity

Although Candida tropicalis has become an increasingly important human pathogen, little is known regarding its potential to cause disease. In this study we evaluated the phenotypic switching ability of C. tropicalis and analyzed the effect of switching on biological properties related to virulence factors. We demonstrated that C. tropicalis switched spontaneously, reversibly and at high frequency (10(-1) to 10(-3)) when grown on yeast extract-peptone-D-glucose (YPD) agar medium. Phenotypic switching in five clinical isolates of C. tropicalis resulted in colonies exhibiting the following morphologies: crepe, rough, crater, irregular center, mycelial and diffuse. The majority of the variant colonies were associated with higher percentages of filamentous growth relative to their parental unswitched isolates. Significant differences (P < 0.05) in the production of hemolytic factor were found between most of the switched variants and their respective parental counterparts. Variant colonies exhibiting the crepe (derived from isolates 49.07 and 100.10) and rough phenotype (derived from isolate 49.07) had higher biofilm formation than their parental counterparts exhibiting a smooth dome surface (P < 0.05). Our data revealed that switching was correlated with changes in the in vitro minimum inhibitory concentrations (MICs) of a subset of the switched variants phenotypes to itraconazole. While the MIC to itraconazole was higher for crepe variant compared with its parental isolate 49.07, the rough variant of 100.10 had a lower MIC to this antifungal agent. The presented data support the role of phenotypic switching in promoting changes in phenotypic expression of putative virulence traits and itraconazole susceptibility of clinical isolates of C. tropicalis.

Evaluation of the conjunctival fungal flora and its susceptibility to antifungal agents in healthy horses in Switzerland

To characterize the conjunctival fungal flora and to determine the susceptibility of 2 isolated molds to antifungal drugs in samples of 64 healthy horses from The National Stud in Switzerland. Conjunctival cytobrush samples were collected from both eyes of 64 ophthalmologically normal horses in August 2012 and subsequently cultured on Sabouraud's agar medium. Growing fungi were identified and counted. Etests or broth microdilution tests for Aspergillus fumigatus and Eurotium amstelodami were carried out to determine antifungal drug sensitivity. These species had previously been detected in samples from eyes with keratomycosis in Switzerland. Minimal inhibitory concentrations (MICs) for voriconazole, fluconazole, itraconazole, amphotericin B, and miconazole were recorded. Fifty-nine of the horses were tested positive for fungal growth from at least one eye (92%). Eleven genera of fungi were identified. The most common fungal genera were Alternaria, Eurotium, Rhizopus, and Cladosporium. Aspergillus spp. and Penicillium spp. were isolated frequently, while no Fusarium spp. was found. In only 2 cases, yeasts were identified as Candida guilliermondii. For certain fungal species, the type of bedding and housing appeared to influence their prevalence. Susceptibility testing of A. fumigatus showed lowest MICs for voriconazole, E. amstelodami for voriconazole and itraconazole. High MICs for fluconazole were detected for all tested fungi while MICs for amphotericin B and miconazole were variable. A large range of fungal mold species was identified including A. fumigatus and E. amstelodami, which have been causative agents of keratomycosis in Switzerland. Best in vitro susceptibility results for these two species were obtained for voriconazole.

H3K4 methyltransferase Set1 is involved in maintenance of ergosterol homeostasis and resistance to Brefeldin A

Set1 is a conserved histone H3 lysine 4 (H3K4) methyltransferase that exists as a multisubunit complex. Although H3K4 methylation is located on many actively transcribed genes, few studies have established a direct connection showing that loss of Set1 and H3K4 methylation results in a phenotype caused by disruption of gene expression. In this study, we determined that cells lacking Set1 or Set1 complex members that disrupt H3K4 methylation have a growth defect when grown in the presence of the antifungal drug Brefeldin A (BFA), indicating that H3K4 methylation is needed for BFA resistance. To determine the role of Set1 in BFA resistance, we discovered that Set1 is important for the expression of genes in the ergosterol biosynthetic pathway, including the rate-limiting enzyme HMG-CoA reductase. Consequently, deletion of SET1 leads to a reduction in HMG-CoA reductase protein and total cellular ergosterol. In addition, the lack of Set1 results in an increase in the expression of DAN1 and PDR11, two genes involved in ergosterol uptake. The increase in expression of uptake genes in set1Δ cells allows sterols such as cholesterol and ergosterol to be actively taken up under aerobic conditions. Interestingly, when grown in the presence of ergosterol set1Δ cells become resistant to BFA, indicating that proper ergosterol levels are needed for antifungal drug resistance. These data show that H3K4 methylation impacts gene expression and output of a biologically and medically relevant pathway and determines why cells lacking H3K4 methylation have antifungal drug sensitivity.

Significant differences in the cell‐wall mannans from three Candida glabrata strains correlate with antifungal drug sensitivity

Candida glabrata is often the second or third most common cause of candidiasis after Candida albicans. C. glabrata infections are difficult to treat, often resistant to many azole antifungal agents and are associated with a high mortality rate in compromised patients. We determined the antigenic structure of the cell-wall mannoproteins from three C. glabrata strains, NBRC 0005, NBRC 0622 and NBRC 103857. (1)H NMR and methylation analyses of the acetolysis products of these mannoproteins showed a significant difference in the amount of the β-1,2-linked mannose residue and side-chain structure. The C. glabrata NBRC 103857 strain contained up to the triose side chains and the nonreducing terminal of the triose was predominantly the β-1,2-linked mannose residue. By contrast, the mannans of the two former strains possessed up to the tetraose side chains and the amount of the β-1,2-linked mannose residue was very low. Larger oligosaccharides than tetraose in the acetolysis products of these mannans were identified as incomplete cleavage fragments by analyzing methylation, (1)H NMR spectra and the α1-2,3 mannosidase degradation reaction. Resistance to the antifungal drugs itraconazole and micafungin was significantly different in these strains. Interestingly, the NBRC 103857 strain, which involved a large amount of the β-1,2-linked mannose residues, exhibited significant sensitivity to these antifungal drugs.

A study of antifungal drug sensitivity of Candida isolated from human immunodeficiency virus infected patients in Chennai, South India

Background:The purpose of this study was to study the drug sensitivity pattern of Candida seen in HIV seropositive patients in Chennai, South India.Materials and Methods:36 oral rinse samples were collected from HIV seropositive individuals with (21 patients) and without (15 patients) clinical candidiasis. The type of Candidiasis, quantitative estimation, differentiation of candida species and antifungal susceptibility testing was done using different tests.Results:In the 21 patients with candidiasis, pseudomembranous type predominated with low CD4 counts and high colony forming units. Antifungal Drug sensitivity test revealed resistance to fluconazole which is attributed to long term exposure to the drug.Conclusion:The results of the study confirm the hypothesis that candidal species can be isolated in HIV positive patients with clinical candidiasis. In HIV infection there are fluconazole resistant candida species emerging mainly due to long term exposure to the drug.

Severe fungal corneal ulcer resulting in infectious endophthalmitis

To analyze causes of serious fungal corneal ulcer resulting in infectious endophthalmitis and explore clinical strategies of avoiding the failure of antifungal therapy. Etiological factors, pre-hospital treatments, clinical features and laboratory findings of 47 inpatients with fungal corneal ulcer resulting in endophthalmitis from January 1999 to December 2008 in Qingdao eye hospital were retrospectively reviewed. Rural residents (95.7%) dominated in 47 cases with a mean age of (49.8 ± 10.1) years. Ocular trauma was the leading cause of fungal corneal ulcer (66.0%). Three patients were ever treated with hormone drugs after the fungal infection. Primary, secondary and tertiary hospital accounted for 68.1%, 17.0% and 14.9% among first medical consultation sites. Diagnostic accuracies of fungal corneal ulcer in three grade hospitals were 31.3%, 62.5% and 71.4% respectively. The average interval from the onset of disease to the admission into our hospital was (29 ± 23) days. The dominating pathogen was genus Fusarium (91.5%) with F. solani (48.9%), F. oxysporum (31.9%) and F. moniliforme (8.5%). Antifungal drug sensitivity tests were performed in 21 patients. The first three sensitive drugs were natamycin (88.9%), voriconazole (78.6%) and amphotericin B (61.9%). The first three drug-resistant ones were miconazole (90.5%), fluconazole (66.7%) and itraconazole (61.9%). Main causes of fungal corneal ulcer resulting in infectious endophthalmitis included lower diagnostic accuracies of first medical consultation in primary hospitals, abuses of non-sensitive drug and delayed treatment of patients. Improving clinical capabilities of doctors in primary hospitals, emphasizing antifungal drug susceptibility tests, and consummating the social security system and the referral system could be effective measures to avoid therapeutic failures.

Prevalence and antifungal drug sensitivity of non-albicans Candida in oral rinse samples of self-caring elderly

To assess the prevalence and antifungal drug sensitivity of non-albicans Candida (NAC) species in elderly outpatients. We investigated oral rinse samples of 194 self-caring elderly population (mean age 83 years) with emphasis on background factors for harbouring NAC. Susceptibility of Candida species to antifungal drugs was determined using standard methodology. Multiple logistic regression analysis was performed taking positive NAC count as the dependent variable and a number of known Candida risk factors as independent variables. Prevalence of candidal carriage of the population was 78.4%, of which 0.5% of the subjects were NAC positive. Candida dubliniensis was the most prevalent NAC species, followed by Candida glabrata and Candida parapsilosis. The NAC positive elderly were more often edentulous with dental prostheses or had fewer teeth than Candida albicans-positive or yeast-negative subjects. Dental caries slightly increased the risk for having NAC strains (odds ratio 1.08), whilst greater age appeared to lower the risk (odds ratio 0.77). Candida species were susceptible to the commonly used antifungal agents in general, but with considerable variation among species. Occasionally, some NAC exhibited lower antifungal susceptibility. The possibility of oral reservoirs of NAC strains which are resistant to common antifungals should be noted in elderly outpatients.

Comparative Transcriptome Analysis Reveals Novel Roles of the Ras and Cyclic AMP Signaling Pathways in Environmental Stress Response and Antifungal Drug Sensitivity in Cryptococcus neoformans

The cyclic AMP (cAMP) pathway plays a central role in the growth, differentiation, and virulence of pathogenic fungi, including Cryptococcus neoformans. Three upstream signaling regulators of adenylyl cyclase (Cac1), Ras, Aca1, and Gpa1, have been demonstrated to control the cAMP pathway in C. neoformans, but their functional relationship remains elusive. We performed a genome-wide transcriptome analysis with a DNA microarray using the ras1Delta, gpa1Delta, cac1Delta, aca1Delta, and pka1Delta pka2Delta mutants. The aca1Delta, gpa1Delta, cac1Delta, and pka1Delta pka2Delta mutants displayed similar transcriptome patterns, whereas the ras1Delta mutant exhibited transcriptome patterns distinct from those of the wild type and the cAMP mutants. Interestingly, a number of environmental stress response genes are modulated differentially in the ras1Delta and cAMP mutants. In fact, the Ras signaling pathway was found to be involved in osmotic and genotoxic stress responses and the maintenance of cell wall integrity via the Cdc24-dependent signaling pathway. Notably, the Ras and cAMP mutants exhibited hypersensitivity to a polyene drug, amphotericin B, without showing effects on ergosterol biosynthesis, which suggested a novel method of antifungal combination therapy. Among the cAMP-dependent gene products that we characterized, two small heat shock proteins, Hsp12 and Hsp122, were found to be involved in the polyene antifungal drug susceptibility of C. neoformans.

Candida albicans and Candida tropicalis in Oral Candidosis: Quantitative Analysis, Exoenzyme Activity, and Antifungal Drug Sensitivity

Candida albicans and C. tropicalis obtained from whole saliva of patients presenting signs of oral candidosis were assayed for quantification of colony forming units, exoenzyme activity (phospholipase and proteinase) and antifungal drug sensitivity (amphotericin B, fluconazole and itraconazole) by the reference method of the Clinical and Laboratory Standards Institute. The number of colony forming units per milliliter varied according to the Candida species involved and whether a single or mixed infection was present. Proteinase activity was observed in both C. albicans and C. tropicalis, but phospholipase activity was noted only in C. albicans. In vitro resistance to antifungals was verified in both species, but C. tropicalis appears to be more resistant to the tested antifungals than C. albicans.