Antifungal Resistance Of Candida Species Research Articles

Antifungal Resistance in Candida Species: A Bit from the Totality

Abstract: Resistance to antifungals is one of the natural protection processes developed by fungi to promote their persistence. Exposure of fungi to these agents over long periods due to improper prescription or a contaminated environment increases the resistance problem. Microbiology related to fungal species and clinical settings related to the therapeutic failure of antifungal drugs are two concepts used to define resistance. The minimum inhibitory concentration (MIC) measurement is the common criterion for determining antifungal resistance. Candida spp. is the most common group of fungi that has developed resistance to different antifungal agents. C. albicans has shown resistance to numerous antifungal agents from this genus, followed by non-albicans Candida (NAC). The majority of resistance is to the azole group of antifungal agents through various mechanisms. Resistance to echinocandins is also reported in many species of Candida, while resistance to polyene has been observed in rare cases. The mechanism of resistance action is generally related to a genetic mutation, which changes the mechanisms of diffusion, fungal structure, and drug degradation. Biofilm formation also contributes to antifungal resistance. Current information on the nature and mechanism of antifungal resistance in Candida spp. is briefly presented in this review.

Screening for anti-fungal resistance in Candida species using chromogenic agar dilution

Screening for anti-fungal resistance in Candida species using chromogenic agar dilution

Molecular Mechanisms Associated with Antifungal Resistance in Pathogenic Candida Species.

Candidiasis is a highly pervasive infection posing major health risks, especially for immunocompromised populations. Pathogenic Candida species have evolved intrinsic and acquired resistance to a variety of antifungal medications. The primary goal of this literature review is to summarize the molecular mechanisms associated with antifungal resistance in Candida species. Resistance can be conferred via gain-of-function mutations in target pathway genes or their transcriptional regulators. Therefore, an overview of the known gene mutations is presented for the following antifungals: azoles (fluconazole, voriconazole, posaconazole and itraconazole), echinocandins (caspofungin, anidulafungin and micafungin), polyenes (amphotericin B and nystatin) and 5-fluorocytosine (5-FC). The following mutation hot spots were identified: (1) ergosterol biosynthesis pathway mutations (ERG11 and UPC2), resulting in azole resistance; (2) overexpression of the efflux pumps, promoting azole resistance (transcription factor genes: tac1 and mrr1; transporter genes: CDR1, CDR2, MDR1, PDR16 and SNQ2); (3) cell wall biosynthesis mutations (FKS1, FKS2 and PDR1), conferring resistance to echinocandins; (4) mutations of nucleic acid synthesis/repair genes (FCY1, FCY2 and FUR1), resulting in 5-FC resistance; and (5) biofilm production, promoting general antifungal resistance. This review also provides a summary of standardized inhibitory breakpoints obtained from international guidelines for prominent Candida species. Notably, N. glabrata, P. kudriavzevii and C. auris demonstrate fluconazole resistance.

Isolation, identification, and antifungal resistance of Candida species from various samples

This study in Aden, Yemen, collected 67 samples from patients attending hospitals and laboratories. Samples were taken from different body areas, covering various age groups and genders. Fungal infections, particularly Candida species, are a significant cause of death worldwide. The emergence of azole-resistant Candida has raised concerns and highlighted the need for better antifungal agents.In the study, 68.66% of the collected samples contained pathogenic Candida fungi. Some samples also showed bacterial growth or both bacteria and fungi. Suspected Candida growth on corn meal agar exhibited chlamydospore formation and germ tubes on human serum. Carbohydrate fermentation tests were positive for Glucose, Maltose, Galactose, and Xylose, while Sucrose and Lactose were negative. All Candida isolates (100%) were accurately identified to the species level using CHROM agar Candida. Candida's pathogenicity was linked to various virulence factors, including hydrolytic enzyme secretion. Nystatin was the most effective antifungal agent (100% sensitivity), while Fluconazole (73.92%) and Amphotericin B (52.17%) showed varying levels of sensitivity. However, Voriconazole, ketoconazole, and Miconazole displayed high resistance rates (89.13%, 84.78%, and 80.44%, respectively) against the isolated Candida.This study concluded that Candida spp., particularly Candida albicans, were frequently found in the samples from patients, with vaginal swaps being a common site of infection. The identification of Candida isolates to the species level using CHROM agar Candida was accurate. Nystatin, Fluconazole, and Amphotericin B were the most effective antifungal agents against Candida spp.

Combination of Farnesol with Common Antifungal Drugs: Inhibitory Effect against Candida Species Isolated from Women with RVVC.

Background and Objectives: Vulvovaginal candidiasis (VVC) is a mucous membrane infection, with an increased rate of antifungal resistance of Candida species. In this study, the in vitro efficacy of farnesol alone or in combination with traditional antifungals was assessed against resistant Candida strains recovered from women with VVC. Materials and Methods: Eighty Candida isolates were identified by multiplex polymerase chain reaction (PCR), and the antifungal susceptibility to amphotericin B (AMB), fluconazole (FLU), itraconazole (ITZ), voriconazole (VOR), clotrimazole (CTZ), and farnesol was tested by the standard microdilution method. The combinations of farnesol with each antifungal were calculated based on the fractional inhibitory concentration index (FICI). Result: Candida glabrata was the predominant species (48.75%) isolated from vaginal discharges, followed by C. albicans (43.75%), C. parapsilosis (3.75%), a mixed infection of C. albicans and C. glabrata (2.5%) and C. albicans and C. parapsilosis (1%). C. albicans and C. glabrata isolates had lower susceptibility to FLU (31.4% and 23.0%, respectively) and CTZ (37.1% and 33.3%, respectively). Importantly, there was "synergism" between farnesol-FLU and farnesol-ITZ against C. albicans and C. parapsilosis (FICI = 0.5 and 0.35, respectively), reverting the original azole-resistant profile. Conclusion: These findings indicate that farnesol can revert the resistance profile of azole by enhancing the activity of FLU and ITZ in resistant Candida isolates, which is a clinically promising result.

High prevalence of fluconazole resistant Candida tropicalis among candiduria samples in China: An ignored matter of concern.

The rapid rise of azole resistance in Candida tropicalis causing invasive infections has become a public health concern; however, the prevalence of resistant isolates in urine samples was not well studied, because the clinical significance of candiduria was not unambiguous due to possible host colonization. We performed a 12-year laboratory-based surveillance study of C. tropicalis causing either invasive infection or candiduria and studied their susceptibility profiles to common antifungal drugs. The complete coding domain sequence of the ERG11 gene was amplified in all fluconazole resistant isolates, and aligned with the wild-type sequence to detect nucleotide mutations. A total of 519 unique C. tropicalis strains isolates, 69.9% of which were isolated from urine samples and remaining 30.1% were invasive strains. Overall, 16.5% isolates were confirmed to be resistant to fluconazole, of which 91.9% were cross-resistant voriconazole. Of note, at the beginning of surveillance (2010-2011), the fluconazole resistance rates were low in both candiduria and invasive groups (6.8% and 5.9%, respectively). However, the resistant rate in the candiduria group significantly increased to 29.5% since 2012-2013 (p = 0.001) and stayed high since then, whilst the resistance rate in the invasive group only showed a gradually increasing trends till 2021 (p > 0.05). Sequence analysis of ERG11 from fluconazole-resistant strains revealed the prevalence of A395T/W mutations were relatively low (16.7%) in the beginning but reached 87.5-100% after 2014. Moreover, the A395W heterozygous mutation isolates became predominant (>60% of resistant strains) after 2016, and indeed isolates carrying corresponding amino acid substitution (Y132F) was highly resistant to fluconazole with MIC50 exceeded 256 μg/ml. Our study revealed high azole resistant rate in candiduria with its increasing trends observed much earlier than stains causing invasive infections. Given antimicrobial resistance as a critical "One Health" issue, the emergence of antifungal resistance in Candida species that are common commensal colonizers in the human body should be concerned.

Candida Species Survival Strategies: New Approaches

The incidence of fungal infections has increased significantly in recent years, motivated especially by COVID-19. Candida yeasts are responsible for most of these infections. This commensal yeast is easily found in the oral mucosa, gastrointestinal tract, urogenital tract, skin and mucous membranes of healthy individuals. Under certain circumstances, when there is a disruption of the biological balance, there may be an increase in the multiplication and invasion of host tissues by these microorganisms. The expression of certain virulence factors such as polymorphism, adhesins, proteases and phospholipases and the formation of microbial biofilms, facilitate tissue penetration and confer greater pathogenicity to these yeasts. This mini-review provides information on the current state of knowledge about virulence, including antifungal resistance of Candida species.

The effect of antifungal resistance development on the virulence of Candida species.

In recent years, the relevance of diseases associated with fungal pathogens increased worldwide. Members of the Candida genus are responsible for the greatest number of fungal bloodstream infections every year. Epidemiological data consistently indicate a modest shift toward non-albicans species, albeit Candidaalbicans is still the most recognizable species within the genus. As a result, the number of clinically relevant pathogens has increased, and, despite their distinct pathogenicity features, the applicable antifungal agents remained the same. For bloodstream infections, only three classes of drugs are routinely used, namely polyenes, azoles and echinocandins. Antifungal resistance toward all three antifungal drug classes frequently occurs in clinical settings. Compared with the broad range of literature on virulence and antifungal resistance of Candida species separately, only a small portion of studies examined the effect of resistance on virulence. These studies found that resistance to polyenes and echinocandins concluded in significant decrease in the virulence in different Candida species. Meanwhile, in some cases, resistance to azole type antifungals resulted in increased virulence depending on the species and isolates. These findings underline the importance of studies aiming to dissect the connections of virulence and resistance in Candida species.

Antifungal activity and cytotoxicity study of ZrO2-ZnO bimetallic nanoparticles

Antifungal resistance of Candida species is a growing concern worldwide. Therefore, this study presents the synthesis of ZnO and ZrO2-ZnO nanoparticles. Structural features of the nanoparticles are characterized by DLS, SEM, EDX, UV–Visible and Raman spectroscopy. Thereafter, the investigation of the effect of these nanoparticles on Candida species was performed by disk diffusion and broth microdilution method on C. albicans, C. dubliniensis, C. glabrata, and C. tropicalis. The viability activity was also evaluated. Scanning electron microscopy showed spherically shaped nanoparticles while dynamic light scattering analysis showed ZrO2 (76 nm), ZnO (22 nm) and ZrO2-ZnO samples between 26 nm and 34 nm respectively. The elemental analysis validated that pure samples were synthesized. The Raman spectra shows ZnO nanoparticles of the wurtzite crystal structure having a group theory that confirms the presence of optic nodes with different properties. Our investigations have shown that mixing ZrO2 with ZnO nanoparticles only show inhibition effect on Candida species at high concentration of ZnO against ZrO2 based on the inhibition zone formed in the disk diffusion and the decrease in the growth characteristics recorded from the broth microdilution analysis. The viability study shows that there is no significance difference in viability as a function of time and concentration on the peripheral human mononuclear cells on exposure to the synthesized nanoparticles.

Rise in antifungal resistance of Candida species from clinical samples in a tertiary care hospital, Kolkata.

Rise in antifungal resistance of Candida species from clinical samples in a tertiary care hospital, Kolkata.

Phytomedicine from Middle Eastern Countries: An Alternative Remedy to Modern Medicine against Candida spp Infection.

Candida spp are capable of infecting both normal and immunocompromised individuals. More recently, Candida infections have spread considerably in healthcare settings, especially in intensive care units, where it is the most frequently encountered pathogen. Candida albicans is the commonest species encountered, although infections by non-albicans species have also risen in the past few years. The pathogenicity of Candida is credited to its aptitude to change between yeast and hyphal modes of growth. Candida spp produce biofilms on synthetic materials that protect them and facilitate drug resistance and act as a source for chronic and recurrent infections. Primarily, azoles antifungal agents are utilized to treat Candida infection that targets the ergosterol synthesis pathway in the cell wall. The development of antifungal resistance in Candida species is a major reason for treatment failure, and hence, there is a need to develop newer antifungal molecules and/or modifications of existing antifungals to make them more effective and less toxic. This has led researchers to oversee the plants to discover newer antimicrobials. Middle Eastern countries are well known for their landscape ranging from dry and sandy deserts to snow-capped mountains. However, they comprise enormous plant diversity with over 20,000 different species showing various types of bioactivities, such as anticancer, antidiabetic, and antimicrobial activities. Especially, the antifungal potential of these phytoproducts could be exploited in the clinical setting for therapy. The present review examines some of the promising alternative natural compounds that have been tested and found effective in treating Candida infections in vitro in some Middle Eastern countries.

Antifungal resistance of candida species isolated from HIV patients in a tertiary care hospital, Mysuru, Karnataka

Context:Candidiasis still remains as a common opportunistic infection in patients with human immunodeficiency virus (HIV). Drug resistance has become a serious health concern because of indiscriminate usage and dosage.Aim:To determine the antifungal resistance pattern of Candida albicans and non-albicans Candida (NAC) from HIV patients.Subjects and Methods:The study was carried out in the department of microbiology at a tertiary care hospital. Candida isolates obtained from HIV patients were tested for drug susceptibility by Vitek-2 automated system.Results:Antifungal susceptibility pattern (n=109) revealed that 15% of the isolates were resistant to at-least one and 85% were sensitive to all the drugs tested. About 10% and 19% of C. albicans showed resistance to fluconazole and flucytosine respectively. Among non-albicans tested, only C. tropicalis (14%) exhibited resistance to flucytosine.Conclusions:Knowledge on epidemiology, species prevalence, and drug resistance pattern may guide for effective therapy. This reduces morbidity and also improves the quality of life.

A Systematic Screen Reveals a Diverse Collection of Medications That Induce Antifungal Resistance in Candida Species.

The increasing incidence of and high mortality rates associated with invasive fungal infections (IFIs) impose an enormous clinical, social, and economic burden on humankind. In addition to microbiological resistance to existing antifungal drugs, the large number of unexplained treatment failures is a serious concern. Due to the extremely limited therapeutic options available, it is critical to identify and understand the various causes of treatment failure if patient outcomes are to improve. In this study, we examined one potential source of treatment failure: antagonistic drug interactions. Using a simple screen, we systematically identified currently approved medications that undermine the antifungal activity of three major antifungal drugs-fluconazole, caspofungin, and amphotericin B-on four prevalent human fungal pathogens-Candida albicans, Candida glabrata, Candida parapsilosis, and Candida tropicalis This revealed that a diverse collection of structurally distinct drugs exhibit antagonistic interactions with fluconazole. Several antagonistic agents selected for follow-up studies induce azole resistance through a mechanism that depends on Tac1p/Pdr1p zinc-cluster transcription factors, which activate the expression of drug efflux pumps belonging to the ABC-type transporter family. Few antagonistic interactions were identified with caspofungin or amphotericin B, possibly reflecting their cell surface mode of action that should not be affected by drug efflux mechanisms. Given that patients at greatest risk of IFIs usually receive a multitude of drugs to treat various underlying conditions, these studies suggest that chemically inducible azole resistance may be much more common and important than previously realized.

Antifungal Resistance of Candida Species in Bacolod City, Philippines

Antifungal Resistance of Candida Species in Bacolod City, Philippines

Diversity, frequency and antifungal resistance of Candida species in patients with type 2 diabetes mellitus

Objective: To determine number, species of Candida and Candida resistance to antifungal therapy according to the metabolic control state and the associated salivary changes in patients with type 2 diabetes mellitus (DM2).Materials and methods: Samples of non-stimulated saliva were collected from 52 patients with DM2. Salivary pH was measured and cultured on Sabouraud glucose agar and the values of CFU/ml were calculated. The species were presumptively identified using CHROMagar Candida® plates, and identification was confirmed by polymerase chain reaction (PCR). C. albicans isolates were cultured on SGA tetracycline agar with nystatin and fluconazole diffusion disks to measure susceptibility.Results: Sixty six percent of the yeasts isolated were Candida albicans, followed by C. glabrata (20.7%). In patients with decompensated DM2, there was an inverse association between HbA1c value and salivary pH. At higher levels of salivary acidification, a greater diversity and quantity of yeasts of the genus Candida were observed. With nystatin, higher inhibition was observed at lower pH.Conclusions: The antifungal therapies could be more effective if it consider, qualitative salivary characteristics as pH, that could determine the susceptibility of species of Candida to at least to nystatin, which is the most used antifungal for treatment to oral candidiasis in patients with DM2.

Phenotypic typing and epidemiological survey of antifungal resistance of Candida species detected in clinical samples of Italian patients in a 17 months' period.

Yeast pathogens are emerging agents of nosocomial as well as community-acquired infections and their rapid and accurate identification is crucial for a better management of high-risk patients and for an adequate treatment. We performed a retrospective review of 156 yeast isolates collected during a 17 months' period of regular clinical practice at the Microbiology Department of San Camillo Hospital in Treviso, Italy and analyzed by the traditional culture-based method combined with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Out of all the samples collected MALDI-TOF MS was able to characterize with a MT score ≥1.7 (accurate result at species level) 12 different yeast and yeast-like species from 140 samples: Candida albicans (63.7%), Candida glabrata (13.6%), Saccharomyces cerevisiae (6.5%), Candida parapsilosis (5.7%), Candida tropicalis (2.1%), Candida pararugosa (2.1%), Candida guilliermondii (2.1%), Candida kefyr (1.4%), Candida lusitaniae (0.7%), Candida palmioleophila (0.7%), Geotrichum silvicola (0.7%), Rhodotorula mucilaginosa (0.7%). Susceptibility testing toward seven common antifungal agents showed a characteristic MIC distribution of C. albicans isolates for echinocandins: particularly we noticed that 72% and 46% of C. albicans showed an MIC value close to clinical breakpoint as defined by EUCAST, respectively for anidulafungin and micafungin. Accurate identification of microorganisms and the study of their antifungal susceptibility allow to understand the epidemiology of a particular area, permitting the choice of the most appropriate early antifungal treatment.

Antifungal resistance of Candida species isolated from Iraqi women infected with vulvovaginal Candidiasis

The prevalence of vulvovaginal candidiasis caused by C. albicans and other Candida species has increased dramatically over the past few decades. Vaginal cultures and susceptibility testing of these Candida species to antifungal are not routinely obtained. Therefore the aims of this study were to1. Determine the Candida species distribution among infected women with vulvovaginal candidiasis2. Prevalence of antifungal resistance among isolated Candida speciesOne handerd vaginal swabs were collected from women their age ranged from 17-40 years old with signs and symptoms of vulvovaginitis attending Medical City Hospital. All swabs were submitted to mycological study (microscopical examination, culture, full identification by performing germ tube test and Api®- candida). Finally, susceptibility testing was curried out by using modified disc diffusion method with six antifungal agents Amphotericin B, Nystatin, Fluconazole, Ketoconazole, Clotrimazole and Econazole. C. albicans was the most frequent species. (61.66%) followed by C.glabrata (33.33%) and only one isolate (1.6%) of C.tropicalis,C.krusie and C.kefyr, so the frequency of overall of other Candida species was (38.13%). However, few resistant C.albicans isolates were found against Fluconazole (21.62%), Ketoconazole (8.1%) and Econazole (5.4%).While no resistant was observed in C.albicans against Clotrimazole. Most of other Candida species were resistant to azoles specially among most isolates of C. glabrata to Ketoconazole 75%. Clotrimazole 70%, Fluconazole 65% and Econazole 20%. Our results showed elevated frequency of the overall of other Candida species particularly C. glabrata which the most prevalent species followed by C.albicans. Other Candida species specially C.glabrata were resistant to azoles in contrast to the most of C.albicans therefore culture from women with vulvovaginal candidiasis should be obtained to detect other Candida species

Candidemia profile and antifungal drugs susceptibility pattern in neonatal intensive care unit patients in a tertiary care teaching institute in Maharashtra

Background: Invasive candidiasis is one of the most commonly encountered problems in neonatal intensive care unit (NICU) leading to substantial morbidity and mortality. Recent studies show an increase in antifungal resistance of candida species. Therefore, species identification with antifungal susceptibility pattern of Candida isolates is very important and helps in the selection of appropriate antifungal agents to prevent the emergence of drug resistance and successful treatment. Methods: Seven thirty four blood culture samples from 244 patients of NICU were tested. Yeast isolates from these blood cultures were identified by conventional methods. Anti-fungal susceptibility testing was done according to CLSI M44A guidelines for Fluconazole, Voriconazole, ketoconazole, Amphotericin-B and Itraconazole. Result: From 118 isolates c. albicans were 37.28 % and remaining 62.72% were non-albicans candida species including c.glabrata (28.81%), c.parapsilosis (14.4%), c.tropicalis (12.71%) and other (6.77%). From all isolates of candida species, Fluconazole, Amphotericin B and ketoconazole were sensitive in 61.0%, 86.4% and 99.1% patients respectively. Voriconazole and Itraconazole were 100% sensitive. Conclusion: Although previously Candida albicans accounted for majority cases of candidiasis, recently NAC species have been increasingly reported in neonatal intensive care units. Amphotericin B should be reserved for life threatening conditions and extended spectrum azole drugs like Voriconazole, Itraconazole and ketoconazole can be good alternatives for treating these infections. DOI: 10.21276/APALM.2017.1000

ALS1 and ALS3 gene expression and biofilm formation in Candida albicans isolated from vulvovaginal candidiasis

Background:A cluster of genes are involved in the pathogenesis and adhesion of Candida albicans to mucosa and epithelial cells in the vagina, the important of which is agglutinin-like sequence (ALS) genes. As well as vaginitis is a significant health problem among women, the antifungal resistance of Candida species is continually increasing. This cross-sectional study investigates the expression of ALS1 and ALS3 genes and biofilm formation in C. albicans isolate isolated from vaginitis.Materials and Methods:Fifty-three recognized isolates of C. albicans were collected from women with recurrent vulvovaginal candidiasis in Iran, cultured on sabouraud dextrose agar, and then examined for gene expression. Total messenger RNA (mRNA) extracted from C. albicans isolates and complementary DNA synthesized using reverse transcriptase enzyme. Reverse transcription-polymerase chain reaction (RT-PCR) using specific primer was used to evaluate the expression of ALS1 and ALS3 through housekeeping (ACT1) genes. 3-(4,5-dimethyl-2-thiazyl)-2,5-diphenyl-2H-tetrazolium bromide assay was performed to assess adherence capacity and biofilm formation in the isolated.Results:Forty isolates (75.8%) expressed ALS1 and 41 isolates (77.7%) expressed ALS3 gene. Moreover, 39 isolates (74%) were positive for both ALS1 and ALS3 mRNA by the RT-PCR. Adherence capability in isolates with ALS1 or ALS3 genes expression was greater than the control group (with any gene expression), besides, it was significantly for the most in the isolates that expressed both ALS1 and ALS3 genes simultaneously.Conclusion:The results attained indicated that there is an association between the expression of ALS1 and ALS3 genes and fluconazole resistance in C. albicans. A considerable percent of the isolates expressing the ALS1 and ALS3 genes may have contributed to their adherence to vagina and biofilm formation.

Candida profiles and antifungal resistance evolution over a decade in Lebanon.

Infection with and antifungal resistance of Candida species have been on the rise globally. Relevant data on these pathogens are relatively few in our region, including Lebanon, thus warranting this study. This retrospective study of Candida spp. profiles and their in vitro antifungal susceptibility was based on analysis requests for 186 Candida non-albicans and 61 C. albicans during three periods (2005-2007, 2009-2011, and 2012-2014) over the span of the last 10 years at the American University of Beirut Medical Center (AUBMC), a major tertiary care center in Lebanon. Identification of Candida was done using the API 20C AUX system, and the E-test was used to determine the minimum inhibitory concentrations (MICs) of antifungal agents. Among the 1,300-1,500 Candida isolates recovered yearly, C. albicans rates decreased from 86% in 2005 to around 60% in 2014. Simultaneously, the non-albicans rates increased from 14% in 2005 to around 40% in 2014, revealing 11 species, the most frequent of which were C. tropicalis, C. glabrata, and C. parapsilosis. All these demonstrated high resistance (35%-79%) against itraconazole, but remained uniformly susceptible (100%) to amphotericin B. Though C. albicans and the other species maintained high susceptibility against fluconazole and voriconazole, their MIC90 showed an elevated trend over time, and C. glabrata had the highest resistance rates. The observed rise in resistance among Candida spp. in Lebanon mandates the need for close surveillance and monitoring of antifungal drug resistance for both epidemiologic and treatment purposes.