Concerning the presumptive identification of Candida kefyr on Uriselect™4 agar / Sobre la identificación presuntiva de Candida kefyr en agar Uriselect™4

Introduction. Non-albicans Candida species, such as Candida kefyr, are emerging pathogens. Chromogenic media are highly useful for the diagnosis of urinary tract infections (UTIs). The aim was to describe the behavior of this specie on a non-specific chromogenic medium. Material and methods. A retrospective study of cases of candiduria detected in the Microbiology laboratory of the Virgen de las Nieves Hospital in Granada (Spain) between 2016 and 2021 (N=2,130). Urine samples were quantitatively seeded on non-selective UriSelect™4 chromogenic agar. Results. Between 2016 and 2021, C. kefyr was the seventh most frequent Candida species responsible for candiduria in our setting (n=15). The macroscopic appearance of C. kefyr colonies, punctiform and bluish, allowed the direct identification of these microorganisms. Conclusions. This study provides the first description of the specific behavior of C. kefyr on UriSelect™4 agar, which differentiates it from other Candida species based on its enzymatic characteristics. (AU)

Introducción. Las especies de Candida no-albicans, como Candida kefyr, son patógenos emergentes. Los medios cromogénicos son muy útiles para el diagnóstico de infecciones del tracto urinario (ITU). El objetivo era describir el comportamiento de esta especie en un medio cromogénico no específico. Material y métodos. Estudio retrospectivo de casos de candiduria detectados en el laboratorio de Microbiología del Hospital Virgen de las Nieves de Granada (España) entre 2016 y 2021 (N=2.130). Las muestras de orina se sembraron cuantitativamente en agar cromogénico no selectivo Uri Select™4. Resultados. C. kefyr fue la séptima especie de Candida responsables de la candiduria en nuestro medio (n = 15). El aspecto macroscópico de las colonias de C. kefyr, puntiformes y azuladas, permitió su identificación presuntiva directamente. Conclusiones. Este estudio proporciona la primera descripción del comportamiento específico de C. kefyr en agar Uri Select™4, que lo diferencia de otras especies de Candida en función de sus características enzimáticas. (AU)

Concerning the presumptive identification of Candida kefyr on Uriselect™4 agar.

OBJECTIVE: Non-albicans Candida species, such as Candida kefyr, are emerging pathogens. Chromogenic media are highly useful for the diagnosis of urinary tract infections (UTIs). The aim was to describe the behavior of this specie on a non-specific chromogenic medium. METHODS: A retrospective study of cases of candiduria detected in the Microbiology laboratory of the Virgen de las Nieves Hospital in Granada (Spain) between 2016 and 2021 (N=2,130). Urine samples were quantitatively seeded on non-selective UriSelect™4 chromogenic agar. RESULTS: Between 2016 and 2021, C. kefyr was the seventh most frequent Candida species responsible for candiduria in our setting (n=15). The macroscopic appearance of C. kefyr colonies, punctiform and bluish, allowed the direct identification of these microorganisms. CONCLUSIONS: This study provides the first description of the specific behavior of C. kefyr on UriSelect™4 agar, which differentiates it from other Candida species based on its enzymatic characteristics.

Molecular Characterization and Sterol Profiles Identify Nonsynonymous Mutations in ERG2 as a Major Mechanism Conferring Reduced Susceptibility to Amphotericin B in Candida kefyr.

The molecular basis of reduced susceptibility to amphotericin B (rs-AMB) among any yeasts is poorly defined. Genetic alterations in genes involved in ergosterol biosynthesis and total cell sterols were investigated among clinical Candida kefyr isolates. C. kefyr isolates (n = 81) obtained from 74 patients in Kuwait and identified by phenotypic and molecular methods were analyzed. An Etest was initially used to identify isolates with rs-AMB. Specific mutations in ERG2 and ERG6 involved in ergosterol biosynthesis were detected by PCR sequencing. Twelve selected isolates were also tested by the SensiTitre Yeast One (SYO), and total cell sterols were evaluated by gas chromatography-mass spectrometry and ERG3 and ERG11 sequencing. Eight isolates from 8 patients showed rs-AMB by Etest, including 2 isolates with additional resistance to fluconazole or to all three antifungals. SYO correctly identified 8 of 8 rs-AMB isolates. A nonsynonymous mutation in ERG2 was detected in 6 of 8 rs-AMB isolates but also in 3 of 73 isolates with a wild-type AMB pattern. One rs-AMB isolate contained a deletion (frameshift) mutation in ERG2. One or more nonsynonymous mutations was detected in ERG6 in 11 of 81 isolates with the rs-AMB or wild-type AMB pattern. Among 12 selected isolates, 2 and 2 isolates contained a nonsynonymous mutation(s) in ERG3 and ERG11, respectively. Ergosterol was undetectable in 7 of 8 rs-AMB isolates, and the total cell sterol profiles were consistent with loss of ERG2 function in 6 rs-AMB isolates and loss of ERG3 activity in another rs-AMB isolate. Our data showed that ERG2 is a major target conferring rs-AMB in clinical C. kefyr isolates. IMPORTANCE Some yeast species exhibit intrinsic resistance or rapidly acquire resistance to azole antifungals. Despite >50 years of clinical use, resistance to amphotericin B (AMB) among yeast species has been extremely rarely reported until recently. Reduced susceptibility to AMB (rs-AMB) among yeast species is, therefore, a matter of serious concern due to the availability of only four classes of antifungal drugs. Recent studies in Candida glabrata, Candida lusitaniae, and Candida auris have identified ERG genes involved in ergosterol biosynthesis as the major targets conferring rs-AMB. The results of this study also show that nonsynonymous mutations in ERG2 impair its function, abolish ergosterol from C. kefyr, and confer rs-AMB. Thus, rapid detection of rs-AMB among clinical isolates will help in proper management of invasive C. kefyr infections.

Prevalence and species distribution of Candida bloodstream infection in children and adults in two teaching university hospitals in Egypt: first report of Candida kefyr.

BACKGROUND: Candidemia is a pervasive problem associated with significant morbidity and mortality in health care settings. This study aimed to determine the changing distribution of Candida species and the emergence of uncommon species. METHODS: This was a cross-sectional study performed in two Cairo University hospitals between 2019 and 2020. All Candida species isolates recovered from blood cultures of adults and pediatrics patients admitted to the hospitals were included. Candida isolates were identified by chromogenic Candida agar and Vitek2 YST identification card. Candida kefyr was confirmed by chip array. RESULTS: Candida species were responsible for 1.6% of bloodstream infections in adults and 10.8% in pediatric patients. C. albicans was the most prevalent species representing 27.8% in adults and 48.3% in pediatrics. Non-albicans species (NAC) represented the most isolated Candida species among adults and pediatrics (72.2% and 51.6%, respectively) with the predominance of C. tropicalis (27.8% and 22.5%, respectively) followed by C. parapsilosis (16.7% and 10.8%, respectively). The uncommon Candida, which is Candida species other than C. albicans, C. parapsilosis, C. tropicalis, C. glabrata, and C. krusei, represents 16.6% and 14% of all candidemia in adults and pediatrics, respectively. Only one of each of C. lusitaniae, C. utilis, and C. kefyr were detected in adults. C. lusitaniae was the most frequently recovered uncommon Candida among pediatrics resulting in 6.4% of candidemia followed by C. famata (4.3%), C. utilis (2.2%), and C. kefyr (1.1%). CONCLUSIONS: C. albicans is still the primary species isolated from pediatrics and adults with candidemia despite the considerable shift to the non-albicans species. C. tropicalis and C. parapsilosis are the most prevalent NAC. The increased prevalence of uncommon Candida species is alarming and necessitates a prompt stewardship program.

Overview on the Infections Related to Rare Candida Species.

Atypical Candida spp. infections are rising, mostly due to the increasing numbers of immunocompromised patients. The most common Candida spp. is still Candida albicans; however, in the last decades, there has been an increase in non-Candida albicans Candida species infections (e.g., Candida glabrata, Candida parapsilosis, and Candida tropicalis). Furthermore, in the last 10 years, the reports on uncommon yeasts, such as Candida lusitaniae, Candida intermedia, or Candida norvegensis, have also worryingly increased. This review summarizes the information, mostly related to the last decade, regarding the infections, diagnosis, treatment, and resistance of these uncommon Candida species. In general, there has been an increase in the number of articles associated with the incidence of these species. Additionally, in several cases, there was a suggestive antifungal resistance, particularly with azoles, which is troublesome for therapeutic success.

Invasive Candida kefyr infection presenting as pyelonephritis in an ICU hospitalized COVID-19 patient: Case report and review of the literature.

Candida kefyr (Kluyveromyces marxianus), an ascomycetous environmental yeast, occasionally isolated from dairy products, represents an uncommon but emerging pathogen in immunocompromised patients. Herein, we present a case of C. kefyr pyelonephritis in a 41-year-old, previously immunocompetent, patient who was hospitalized in an COVID-19 ICU. Pyelonephritis was associated with caliectasis and obstruction due to possible fungus ball formation. Predisposing factors included ICU stay, use of broad spectrum antibiotics and steroids, central venous catheterization, mechanical ventilation and urologic manipulation. Susceptibility testing revealed high MIC values to amphotericin B. Infection was effectively controlled by prolonged administration of fluconazole without further surgical intervention. COVID-19 complicated with invasive candidiasis is an increasingly observed clinical situation that warrants high suspicion index and careful evaluation of laboratory data.

Acid stress responses of Lactobacillus amylovorus and Candida kefyr isolated from fermented sorghum gruel and their application in food fermentation.

Exposure of lactic acid bacteria (LAB) and yeasts to adverse fluctuations during fermentation causes stress; consequently, microbes develop adaptive responses. In this study, we investigated the physiological and proteomic responses of LAB and yeast to acid stress and their application in food fermentation. The physiological and proteomic responses of Lactobacillus amylovorus LS07 and Candida kefyr YS12 to acid stress were measured using turbidimetry, SDS-PAGE, and LC-MS/MS. The technique previously reported by the Association of Official Analytical Chemists (AOAC) was employed to evaluate the physicochemical and organoleptic properties of sorghum gruel fermented using LAB and yeast alone and in combination as starter cultures and spontaneous fermentation as a control. The growth of L. amylovorus LS07 was optimal at pH 1.0, and that of C. kefyr YSI2 was optimal at pH 4. An increased intensity of 30S ribosomal protein S2 (L. amylovorus LS07) and 6-phosphogluconate dehydrogenase (C. kefyr YS12) was observed at pH 1 and 4, respectively, suggesting increased microbial metabolism, thereby reducing the stress. Sorghum gruel produced with combined starters had the highest crude protein (10.94%), iron content (0.0085%), and organoleptic acceptability (7.29), which was significantly different from the products produced with the single starters and the control. The combined starter (L. amylovorus LS07 and C. kefyr YSI2) adapted to stress yielded foods with improved sensory properties, minerals, and reduced anti-nutrient contents.

Cutaneous candidiasis caused by Candida kefyr.

Candidiasis is an acute or subacute fungal infection caused by fungi that belongs to candida genus, with Candida albicansbeing the most frequent causative agent. Candida kefyr is a rare cause of candidiasis which has been reported in systemic candidiasis and deep infections. However, to date, it has never been reported as a cause in dermatophytosis. We report a case of candidiasis caused by Candida kefyr in a 72-year-old woman with a chief complaint of pruritic erythematous rash on the back from one day prior to admission. Diagnosis was established based on clinical features, direct microscopic examination with 10% potassium hydroxide solution, gram staining. The fungal species was determined by carbohydrate fermentation test which showed a positive result for Candida kefyr. The patient was treated with miconazole cream and fusidic cream and showed significant clinical improvement.

An Unusual Case of Candida kefyr Fungemia in an Immunocompromised Patient.

An immunocompromised patient with a known history of cerebrovascular accident (CVA) with right-sided hemiparesis of long duration, type 2 diabetes mellitus, and hypertension presented with signs of rhabdomyolysis and later acute kidney injury (AKI). He subsequently developed Guillain Barre syndrome. Initially, hemodialysis was followed by plasmapheresis. After hemodialysis, the patient presented with multiple episodes of vomiting and weakness of all limbs. A culture showed growth of Enterococcus faecalis, and on Day 6, a bloodstream infection with Candida kefyr and a urinary tract infection with Enterococcus faecalis were diagnosed. We report a rare case of bloodstream infection due to C. kefyr.

Stone induced ureteral rupture: The worst-case scenario. A case report.

Forniceal rupture secondary to acute ureteral obstruction is relatively common. However, spontaneous ureteral rupture is less frequently encountered. Most reported cases were stone related, localized at the ureteropelvic junction and managed in a minimally invasive manner. We present a case of stone induced ureteral rupture below the UPJ, with bacterial and fungal superinfections, that failed conservative management and lead eventually to nephrectomy. No such scenario has ever been reported in the literature. As rupture of the ureter can cause serious complications, including urinoma, sepsis and sometimes kidney loss, prompt recognition, treatment and follow-up of the condition is therefore necessary.

First case of Kluyveromyces marxianus (Candida kefyr) late onset keratitis after lamellar endothelial corneal graft.

We present a case of Kluyveromyces marxianus keratitis nine months after Descement's membrane endothelial keratoplasty (DMEK) in a patient with Fuchs endothelial disease. Endothelial scraping revealed this rare yeast infection at the interface between graft and host cornea. Immediate antifungal treatment with intracameral and corneal intrastromal injections of voriconazole and amphotericin B remained unsuccessful, requiring penetrating keratoplasty. This case highlights the challenging management of keratomycosis in patients with endothelial grafts.

Case Report of a Tubo-ovarian Abscess Caused by Candida kefyr.

BACKGROUND: Candida species are harmless commensals of hosts, including humans, but they can cause infection when the immune system is compromised. Infections with non-albicans species can occur, ranging from urinary tract infections to sepsis, especially among patients in intensive care units. CASE: The patient, a 37-year-old woman, presented with severe abdominal pain, fever, and vomiting. The patient's symptoms and fever continued in spite of treatment with antibiotics, and she underwent exploratory laparotomy. Cyst content culture results showed that Candida kefyr was present in the cyst. CONCLUSION: To the best of our knowledge, this is the first case report of a tubo-ovarian abscess caused by C. kefyr. Rare pathogens can be found in patients with a tubo-ovarian abscess, so culture of the abscess material is important for determining subsequent treatment, particularly in women who require an operation for tubo-ovarian abscess.

Candida and Porphyromonas gingivalis: the effect on wound closure in vitro.

Microorganisms play a role in oral mucositis after cancer therapy. The current study explored the hypothesis that Candida spp. alone and together with Porphyromonas gingivalis cause delayed healing of oral ulcerations due to the inhibition of wound closure. An in vitro scratch assay model was used to study the influence of viable and heat-killed Candida glabrata, Candida kefyr, and Candida albicans on cell migration of oral epithelial cells. Separately, the effect of conditioned medium of Candida spp. and the effect of a mixed infection of Candida spp. with P. gingivalis on wound closure was studied. In the presence of 10 viable C. glabrata or C. kefyr versus one epithelial cell, with a multiplicity of infection (MOI) of 10, the relative closure of the scratch was 26% and 17%, respectively. At a MOI of 1, this was 60% for C. glabrata and 78% for C. kefyr. The inhibition of oral epithelial cell migration challenged with either C. glabrata or C. kefyr together with P. gingivalis was stronger than the inhibition caused by one of both organisms separately. Candida spp. inhibit cell migration in vitro. A combination of Candida spp. and P. gingivalis inhibited cell migration more than either microorganism separately.

Production, purification, and characterization of metalloprotease from Candida kefyr 41 PSB.

A thermostable metalloprotease, produced from an environmental strain of Candida kefyr 41 PSB, was purified 16 fold with a 60% yield by cold ethanol precipitation and affinity chromatography (bentonite-acrylamide-cysteine microcomposite). The purified enzyme appeared as a single protein band at 43kDa. Its optimum pH and temperature points were found to be 7.0 and 105°C, respectively. Km and Vmax values of the enzyme were determined to be 3.5mg/mL and 4.4µmolmL-1min-1, 1.65mg/mL and 6.1µmolmL-1min-1, using casein and gelatine as the substrates, respectively. The activity was inhibited by using ethylenediamine tetraacetic acid (EDTA), indicating that the enzyme was a metalloprotease. Stability of the enzyme was investigated by using thermodynamic and kinetic parameters. The thermal inactivation profile of the enzyme conformed to the first order kinetics. The half life of the enzyme at 95, 105, 115, 125 and 135°C was 1310, 610, 220, 150, and 86min, respectively.

Antifungal therapies in murine infections by Candida kefyr.

Candida kefyr is an emerging pathogen able to cause disseminated infection, especially in immunocompromised patients. Although guidelines for the treatment of invasive candidiasis have been published, no specific recommendations against C. kefyr are available. We determine the in vitro killing activity of amphotericin B (AMB), fluconazole (FLC) and caspofungin (CFG) as well as their efficacy in a murine model of systemic infection by two C. kefyr strains. Time-kill curves of AMB, FLC and CFG were determined in final volumes of 10 ml containing the assayed drugs ranged from 0.03 to 32 µg ml-1 at different time points and efficacy of the drugs was evaluated in a systemic model of candidiasis, conducted in immunosuppressed mice, through survival, (1→3)-ß-D-glucan levels in serum and fungal load in kidneys. AMB and CFG showed fungicidal and FLC fungistatic activity against both isolates. The three drugs were able to reduce fungal burden in kidneys and (1→3)-ß-D-glucan concentration in serum of infected mice, with CFG showing the highest efficacy, followed by FLC. In conclusion, CFG showed efficacy over AMB and FLC against the systemic candidiasis by C. kefyr. The established epidemiological cut-off for anidulafungin seems the best indicator of outcome for echinocandins.

Candida kefyr as a cause of bloodstream infection and adjunctive role of biomarkers in its diagnosis.

A rare case of bloodstream infection caused by Candida kefyr is described. The diagnosis was established by repeatedly isolating the yeast in blood cultures and by detecting C. kefyr-specific DNA in serum samples. Demonstration of elevated serum levels of ß-D-glucan and Candida mannan also provided additional diagnostic evidence. The identity of the isolates was confirmed by PCR sequencing of the ITS region of rDNA. This is the first report of C. kefyr candidemia from Kuwait and the Middle East. The report highlights emerging clinical significance of rare Candida spp. in etiology of candidemia and reinforces the adjunctive role of biomarkers in diagnosis.

Two missense mutations, E123Q and K151E, identified in the ERG11 allele of an azole-resistant isolate of Candida kefyr recovered from a stem cell transplant patient for acute myeloid leukemia.

We report on the first cloning and nucleotide sequencing of an ERG11 allele from a clinical isolate of Candida kefyr cross-resistant to azole antifungals. It was recovered from a stem cell transplant patient, in an oncohematology unit exhibiting unexpected high prevalence of C. kefyr. Two amino acid substitutions were identified: K151E, whose role in fluconazole resistance was already demonstrated in Candida albicans, and E123Q, a new substitution never described so far in azole-resistant Candida yeast.

Candida kefyr in Invasive Paranasal Sinusitis.

Fungi are being increasingly implicated in etio pathology of rhino sinusitis. Invasive fungal sinusitis occurring in diabetics and immunocompromised patients is notorious for its insidious onset, rapid intra cranial spread and tissue destruction. Candida as a cause of this invasive infection is infrequently reported in India. We report a rare species of Candida, Candida kefyr in a female diabetic patient presenting with invasive fungal sinusitis.

Comparison of ethanol production from cheese whey permeate by two yeast strains.

The objective of the present laboratory scale experiment was to compare ethanol production by Kluyveromyces marxianus strain ATCC8554 and Candida kefyr ATCC 14245 from unconcentrated and concentrated cheese whey permeate. The results indicated that ethanol production was greater when using concentrated whey permeate (9.8% lactose) compared to unconcentrated whey permeate (4.9% lactose) by both the yeasts, especially in presence of growth supplements. The rate and extent of ethanol formation increased noticeably and partly linearly for both the yeasts with sharp and partly linear decrease in both lactose and Chemical Oxygen Demand (COD), especially after the first 10 h of fermentation; total time of fermentation was 60 h. The optimum pH and temperature conditions for ethanol production were 4.8 and 30º C respectively. Klu. marxianus strain had greater ethanol producing ability from cheese permeate whey than Can. kefyr.