Candida fermentati as a cause of persistent fungemia in a preterm neonate successfully treated by combination therapy with amphotericin B and caspofungin

Spectrum and management of rare Candida/yeast infections in Kuwait in the Middle East

Invasive fungal infections (IFIs) are associated with high mortality rates and mostly affect patients with compromised immunity. The incidence of IFIs is increasing worldwide with the expanding population of susceptible patients. Candida and other yeast infections represent a major component of IFIs. Rare Candida/yeast infections have also increased in recent years and pose considerable diagnostic and management challenges as they are not easily recognized by routine phenotypic characteristic-based diagnostic methods and/or by the automated yeast identification systems. Rare Candida/yeasts also exhibit reduced susceptibility to antifungal drugs making proper management of invasive infections challenging. Here, we review the diagnosis and management of 60 cases of rare Candida/yeast IFIs described so far in Kuwait, an Arabian Gulf country in the Middle East. Interestingly, majority (34 of 60, 56.7%) of these rare Candida/yeast invasive infections occurred among neonates or premature, very-low-birth-weight neonates, usually following prior bacteremia episodes. The clinical details, treatment given, and outcome were available for 28 of 34 neonates. The crude mortality rate among these neonates was 32.2% as 19 of 28 (67.8%) survived the infection and were discharged in healthy condition, likely due to accurate diagnosis and frequent use of combination therapy. Physicians treating patients with extended stay under intensive care, on mechanical ventilation, receiving broad spectrum antibiotics and with gastrointestinal surgery/complications should proactively investigate IFIs. Timely diagnosis and early antifungal treatment are essential to decrease mortality. Understanding the epidemiology and spectrum of rare Candida/yeast invasive infections in different geographical regions, their susceptibility profiles and management will help to devise novel diagnostic and treatment approaches and formulate guidelines for improved patient outcome.

Meyerozyma guilliermondii species complex: review of current epidemiology, antifungal resistance, and mechanisms

Meyerozyma guilliermondii has been accepted as a complex composed of Meyerozyma guilliermondii, Meyerozyma carpophila, and Meyerozyma caribbica. M. guilliermondii is a saprophyte detected on human mucosa and skin. It can lead to serious infections in patients with risk factors like chemotherapy, immunodeficiency, gastrointestinal or cardiovascular surgery, and oncology disorders. Most deaths related to M. guilliermondii infections occur in individuals with malignancy. In recent decades, incidence of M. guilliermondii infections is increased. Sensitivity of this microorganism to conventional antifungals (e.g., amphotericin B, fluconazole, micafungin and anidulafungin) was reduced. Prophylactic and empirical uses of these drugs are linked to elevated minimal inhibitory concentrations (MICs) of M. guilliermondii. Drug resistance has concerned many researchers across the world. They are attempting to discover appropriate solution to combat this challenge. This study reviews the most important mechanisms of resistance to antifungals developed by in M. guilliermondii species complex.

Fatal Lodderomyces elongisporus Fungemia in a Premature, Extremely Low-Birth-Weight Neonate

Many rare yeasts are emerging as pathogens, causing invasive infections in susceptible hosts that are associated with poor clinical outcome. Here, we describe the first and fatal case of Lodderomyces elongisporus fungemia in a premature, extremely low-birth-weight neonate after spontaneous vaginal delivery. The bloodstream isolate was identified as C. parapsilosis by the VITEK 2 yeast identification system and as L. elongisporus by PCR-sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA. Antifungal susceptibility testing data for the isolate, performed by the broth microdilution-based MICRONAUT-AM assay, showed susceptibility to all nine antifungal drugs tested. Despite the initiation of treatment with liposomal amphotericin B, the patient died on the same day that the blood culture yielded yeast growth. This is the first report of L. elongisporus bloodstream infection in a neonate as the previous nine cases reported in the literature occurred in adult patients. The crude mortality rate for invasive L. elongisporus infection is 50%, as only 5 of 10 patients survived.

A Pragmatic Approach to Susceptibility Classification of Yeasts without EUCAST Clinical Breakpoints

EUCAST has established clinical breakpoints for the six most common Candida species and Cryptococcus neoformans but not for less common yeasts because sufficient evidence is lacking. Consequently, the question “How to interpret the MIC?” for other yeasts often arises. We propose a pragmatic classification for amphotericin B, anidulafungin, fluconazole, and voriconazole MICs against 30 different rare yeasts. This classification takes advantage of MIC data for more than 4000 isolates generated in the EUCAST Development Laboratory for Fungi validated by alignment to published EUCAST MIC data. The classification relies on the following two important assumptions: first, that when isolates are genetically related, pathogenicity and intrinsic susceptibility patterns may be similar; and second, that even if species are not phylogenetically related, the rare yeasts will likely respond to therapy, provided the MIC is comparable to that against wild-type isolates of more prevalent susceptible species because rare yeasts are most likely “rare” due to a lower pathogenicity. In addition, the treatment recommendations available in the current guidelines based on the in vivo efficacy data and clinical experience are taken into consideration. Needless to say, it is of utmost importance (a) to ascertain that the species identification is correct (using MALDI-TOF or sequencing), and (b) to re-test the isolate once or twice to confirm that the MIC is representative for the isolate (because of the inherent variability in MIC determinations). We hope this pragmatic guidance is helpful until evidence-based EUCAST breakpoints can be formally established.

The antifungal activity of caspofungin in combination with antifungals or non-antifungals against Candida species in vitro and in clinical therapy

Introduction: Candida species have been regarded as global health threats due to their ability to cause invasive infections. It is challenging to treat Candida bloodstream infections, which are associated with high mortality levels. Monotherapy with antifungals is sometimes not effective against severe Candida infections, and combination therapy is needed in clinical practice.Areas covered: This review was undertaken based on data from a PubMed search for English language reports published before March 2021 by using the terms 'caspofungin,' 'Candida species,' 'combination therapy,' 'antifungal effect,' and 'novel antifungal agent.'Expert opinion: Combination therapy is an empirical strategy for treating refractory Candida infections. Caspofungin has been recommended to treat candidaemia. Caspofungin in combination therapy has some applications, while the efficacy of combination therapy in the treatment of refractory Candida infections needs more study, such as randomized controlled trials. In addition, novel compounds or drugs with potential antifungal activities have been examined, and some of them exhibit synergistic interactions with caspofungin. Thus, the antifungal activity of caspofungin in combination with antifungals or non-antifungals against Candida species in vitro and in clinical therapy is summarized.

Papiliotrema laurentii fungemia in a premature, very low-birth-weight neonate in Kuwait successfully treated with liposomal amphotericin B

Papiliotrema laurentii (formerly Cryptococcus laurentii) and Papiliotrema albidus (formerly Cryptococcus albidus) are yeast-like environmental fungi which are largely considered as non-pathogenic to humans. However, invasive infections caused by P. laurentii have recently been reported in some patients with an impaired immune system. Here, we describe the first case of P. laurentii fungemia in a premature, very low-birth-weight neonate in Kuwait and the Middle East. Repeated bloodstream isolates were obtained and were tentatively identified as P. laurentii by Vitek 2 yeast identification system. The identification of the yeast isolates as P. laurentii was confirmed by PCR-sequencing of ribosomal DNA (rDNA). Antifungal susceptibility testing data showed that the isolates were susceptible to amphotericin B, fluconazole and voriconazole but appeared resistant to caspofungin. The baby was successfully treated with liposomal amphotericin B.

Physiological characterization and molecular identification of some rare yeast species causing onychomycosis

INTRODUCTION

Onychomycosis are infections with a variety of etiological agents. Although dermatophytes are responsible for most infections, yeasts are gaining importance as agents of these pathologies. The use of antifungals has increased the incidence of what had been considered rare or novel pathogens. We reidentify three rare yeasts from a culture collection of onychomycosis agents by matrix-assisted laser desorption/ionization time of flight/mass spectrometry (MALDI-TOF/MS) and sequencing the internal transcribed spacer (ITS) regions or the intergenic spacer (IGS) 1 region of ribosomal DNA (rDNA), and present their enzymatic and antifungal susceptibility profiles.

MATERIAL AND METHODS

We performed a phenotypical characterization and molecular identification of five yeast isolates. We tested the urease, gelatinase, DNase, phospholipase, protease, and esterase activities, as well as the hemolytic activity. We evaluated the antifungal susceptibility to amphotericin B, fluconazole, anidulafungin and caspofungin.

RESULTS

Phenotypic methods could not identify the isolates. MALDI-TOF/MS was able to properly identify Candida duobushameulonii. The five isolates were successfully identified by sequence analysis as Candida duobushaemulonii, Meyerozyma caribbica and Cutaneotrichosporon dermatis. Candida duobushameulonii showed hemolytic, phospholipase, and protease activities. Meyerozyma caribbica was positive for gelatinase and protease activities. All antifungals exhibited minimum inhibitory concentrations (MICs) ≤2μg/mL against both species. The three isolates of Cutaneotrichosporon dermatis showed urease, DNase, and esterase activities, and resistance to echinocandins (MICs ≥8μg/mL), while amphotericin B and fluconazole exhibited low MICs against these isolates (0.50-2μg/mL).

DISCUSSION

Sequencing of the ITS or IGS1 regions of rDNA remains the best method for identifying cryptic species over other commercially available systems. More reports are needed to define the enzymatic and antifungal profiles for these species. This is the first report of Meyerozyma caribbica and Cutaneotrichosporon dermatis as etiological agents of onychomycosis.

Elevated minimum inhibitory concentrations to antifungal drugs prevail in 14 rare species of candidemia-causing Saccharomycotina yeasts

Antifungal susceptibility profiles of rare Saccharomycotina yeasts remain missing, even though an increase in prevalence of such rare Candida species was reported in candidemia. Majority of these rare yeast species carry intrinsic resistances against at least one antifungal compound. Some species are known to be cross-resistant (against multiple drugs of the same drug class) or even multi-drug resistant (against multiple drugs of different drug classes). We performed antifungal susceptibility testing (AFST) according to EUCAST broth microdilution for 14 rare species (Clavispora lusitaniae, Candida intermedia, Candida auris, Diutina rugosa, Wickerhamiella pararugosa, Yarrowia lipolytica, Pichia norvegensis, Candida nivariensis, Kluyveromyces marxianus, Wickerhamomyces anomalus, Candida palmioleophila, Meyerozyma guilliermondii, Meyerozyma caribbica, and Debaryomyces hansenii) known to cause candidemia. In total, 234 isolates were tested for amphotericin B, fluconazole, itraconazole, voriconazole, posaconazole, anidulafungin, micafungin, and caspofungin. Amphothericin B had the broadest efficiency against the 14 tested rare yeast species, while high minimum inhibitory concentrations (MICs) against azole drugs and echinocandins were common. Voriconazole was the most efficient azole drug. Multidrug resistance was observed for the species C. auris and K. marxianus. Multidrug resistant individual isolates were found for Y. lipolytica and M. caribbica. In conclusion, the observed high MIC values of the rare Saccharomycotina species tested limit antifungal treatment options, complicating the management of such infections.

The epidemiology of Candida species in the Middle East and North Africa

In recent decades, the epidemiology of invasive candidiasis (IC) has progressively changed worldwide. This notably includes emergence of several Candida species. Although some surveillance programs provided global trends in IC epidemiology, data from countries from the Middle East and North Africa (MENA) remain scarce. In this manuscript, we reviewed the existing available data on the epidemiology of Candida species associated with IC, particularly candidemia, in MENA region regarding species distribution. As witnessed worldwide, an evident shift of Candidaalbicans towards non-albicansCandida (NAC) has been observed in the MENA region. The worrying emergence of multi-drug resistant Candida species in MENA calls for a better understanding of their epidemiology. This represents an essential prerequisite for the implementation of effective infection control strategies and surveillance systems to prevent IC among high-risk patients.

In vitro activities of six antifungal agents and their combinations against Chaetomium spp

PURPOSE

To assess in vitro activities of six antifungal agents (amphotericin B, itraconazole, voriconazole, posaconazole, caspofungin and terbinafine) and the combined effects of eight pairs of them (caspofungin or terbinafine with amphotericin B, itraconazole, voriconazole or posaconazole) against 22 isolates of Chaetomium spp.

METHODOLOGY

The broth microdilution method drafted by the Clinical and Laboratory Standards Institute and the checkerboard method were used in this study to evaluate in vitro activities of antifungal drugs both alone and in combination against Chaetomium spp.

RESULTS

Amphotericin B and triazoles exhibited lower geometric mean, MIC50 and MIC90 than caspofungin and terbinafine. Besides, all the paired drugs displayed varying degrees of synergism, with the interactions between caspofungin and itraconazole ranking first (86.36 %).

CONCLUSION

Our study illustrated varying degrees of synergism between caspofungin or terbinafine and itraconazole, voriconazole, posaconazole or amphotericin B towards Chaetomium spp., which could be a reference for the clinical treatment of Chaetomium spp. infections.

Changing trends in epidemiology and antifungal susceptibility patterns of six bloodstream Candida species isolates over a 12-year period in Kuwait

Changing trends in incidence and antifungal susceptibility patterns of six Candida species causing candidemia in Kuwait between 2006–2017 are reported. A total of 2075 isolates obtained from 1448 patients were analyzed. Identity of Candida species isolates was determined by phenotypic methods and confirmed by PCR amplification/PCR-sequencing of rDNA and/or MALDI-TOF MS. Antifungal susceptibility was determined by Etest. C. albicans accounted for 539 (37.22%) cases followed by C. parapsilosis (n = 502, 34.67%), C. tropicalis (n = 210, 14.5%), C. glabrata (n = 148, 10.22%), C. krusei (n = 27, 1.81%) and C. dubliniensis (n = 22, 1.5%). The comparative percent distribution of Candida species causing candidemia between 2006–2011 and 2012–2017 was as follows: C. albicans 41.8% and 33.1%, C. parapsilosis complex 32.01% and 37.04%, C. tropicalis 13.59% and 15.31%, and C. glabrata 8.77% and 11.51%, C. krusei 2.0% and 1.7%, and C. dubliniensis 1.75 and 1.3%, respectively. Three of 371 C. albicans isolates during 2006–2011 and five of 363 during 2012–2017 were resistant to fluconazole. Among C. parapsilosis isolates, one of 310 during 2006–2011 and 21 of 446 during 2012–2017 were resistant to this drug. Furthermore, at an epidemiologic cutoff value (ECV) of ≤0.5 μg/ml, 70.1% C. albicans isolates were wild-type for fluconazole during 2006–2011 as compared to 58.1% during 2012–2017. Likewise, at an ECV of ≤2 μg/ml, 98.0% of C. parapsilosis isolates were wild-type during 2006–2011 as compared to 93.4% during 2012–2017. Clonal spread of fluconazole-resistant C. parapsilosis in one major hospital was documented. An 8.8% shift in favor of non-albicans Candida species with concomitant increase in MICs between the two periods preludes emergence of fluconazole-resistant candidemia cases in Kuwait.

Increasing prevalence, molecular characterization and antifungal drug susceptibility of serial Candida auris isolates in Kuwait

Candida auris is an emerging yeast pathogen of global significance. Its multidrug-resistant nature and inadequacies of conventional identification systems pose diagnostic and therapeutic challenges. This study investigated occurrence of C. auris in clinical specimens in Kuwait and its susceptibility to antifungal agents. Clinical yeast strains isolated during 3.5-year period and forming pink-colored colonies on CHROMagar Candida were studied by wet mount examination for microscopic morphology and Vitek 2 yeast identification system. A simple species-specific PCR assay was developed for molecular identification and results were confirmed by PCR-sequencing of rDNA. Antifungal susceptibility testing of one isolate from each patient was determined by Etest. The 280 isolates forming pink-colored colonies on CHROMagar Candida, were identified by Vitek 2 as Candida haemulonii (n = 166), Candida utilis (n = 49), Candida kefyr (n = 45), Candida guilliermondii (n = 9), Candida famata (n = 6) and Candida conglobata (n = 5). Species-specific PCR and PCR-sequencing of rDNA identified 166 C. haemulonii isolates as C. auris (n = 158), C. haemulonii (n = 6) and Candida duobushaemulonii (n = 2). C. auris isolates originated from diverse clinical specimens from 56 patients. Of 56 C. auris isolates tested, all were resistant to fluconazole, 41/56 (73%) and 13/56 (23%) were additionally resistant to voriconazole and amphotericin B, respectively. Eleven (20%) isolates were resistant to fluconazole, voriconazole and amphotericin B. One isolate was resistant to caspofungin and micafungin. Increasing isolation of C. auris in recent years from diverse clinical specimens including bloodstream shows that C. auris is an emerging non-albicans Candida species in Kuwait causing a variety of infections. Inability of conventional identification methods to accurately identify this pathogen and multidrug-resistant nature of many strains calls for a greater understanding of its epidemiology, risk factors for acquiring C. auris infection and management strategies in high-risk patients. This is the first comprehensive study on the emergence of this multidrug-resistant yeast from Kuwait and the Middle East.

Persistent Candida conglobata bloodstream infection in a preterm neonate successfully treated by combination therapy with amphotericin B and caspofungin

Fungemia due to uncommon/rare Candida species is an emerging problem of global clinical significance. Here, we describe a case of Candida conglobata bloodstream infection in a preterm neonate. The diagnosis was established by repeated isolation of C. conglobata in blood cultures and by detection of rDNA of the fungus in serum samples. The identity of the isolate as C. conglobata was confirmed by sequencing of ITS region and D1/D2 domains of rDNA. Despite initial treatment with a liposomal amphotericin B (AmBisome) for 7 days, the blood culture remained positive. The neonate was successfully treated by combination therapy with caspofungin for 25 days. To the best of our knowledge, this is the first proven report unequivocally proving the etiologic role of C. conglobata in bloodstream infection.

Breakthrough fungemia due to Candida fermentati with fks1p mutation under micafungin treatment in a cord blood transplant recipient

The prophylactic use of antifungal drugs in allogeneic hematopoietic cell transplant recipients has revealed that the rate of non-albicans candidemia has increased. We herein report the case of a patient with adult T-cell leukemia who developed candidemia due to Candida fermentati during micafungin treatment after cord blood transplantation. The isolate was identified on day 47 by sequencing of the internal transcribed spacer region of the ribosomal RNA gene. The sequencing of the hot spot region of fks1p of isolate revealed naturally occurring amino acid substitutions, which conferred reduced echinocandin susceptibility. This case highlights that breakthrough candidemia due to C. fermentati occurred in a patient receiving micafungin treatment.

Successful therapy of Candida pulcherrima fungemia in a premature newborn with liposomal amphotericin B and micafungin

New Candida species may cause bloodstream infections challenging current therapeutic approaches because of unpredictable susceptibility and virulence. In the present report, we describe a fungemia case due to Candida pulcherrima in a premature neonate. After full in vitro diagnostic workup, the neonate was successfully treated with liposomal amphotericin B and micafungin achieving rapid fungal eradication from blood.