Nosocomial Candida guilliermondii fungemia in cancer patients

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.

The identification of Meyerozyma guilliermondii from blood cultures and surveillance samples in a university hospital in Northeast Turkey: A ten-year survey

Meyerozyma (Pichia) guilliermondii exists in human skin and mucosal surface microflora. It can cause severe fungal infections like candidemia, which is an opportunistic pathogen. One hundred and forty-one M. guilliermondii isolates, consisting of 122 blood culture isolates, belonging to 126 patients; 13 total parenteral nutrition solution isolates; and two rectal swab isolates were identified according to carbohydrate assimilation reactions in a university hospital in Turkey between January 2006 and December 2015. Following Candida albicans (34.0%) and C. parapsilosis (21.2%), the third yeast species most commonly isolated from blood cultures in the Farabi Hospital was M. guilliermondii (20.6%). The patients were hospitalised in 27 different departments. A total of 50% of the patients were in pediatric departments, 49.2% were in intensive care units, and 17.2% were in haematology-oncology departments. Molecular identification of the isolates was performed using DNA sequence analysis of ribosomal ITS gene regions and IGS amplification-AluI fingerprinting (IGSAF). With molecular identification, 140 isolates were identified as M. guilliermondii and one isolate was identified as Candida membranifaciens. It was observed that the ITS1 region specifically helps in identifying these species. It was demonstrated that biochemical and molecular methods were 99.3% consistent in identifying M. guilliermondii. The Wild-Type (WT) Minimum Inhibitory Concentrations (MICs) distribution of fluconazole, voriconazole, itraconazole, and flucytosine were determined using the Sensititre YeastOne YO2V system after 24h of incubation. One M. guilliermondii strain was determined to be non-WT for fluconazole, voriconazole, itraconazole and flucytosine. In total, three M. guilliermondii strains, for fluconazole, were determined to be non-WT in this study.

Uncommon Candida Species Fungemia among Cancer Patients, Houston, Texas, USA

Many uncommon Candida species that cause bloodstream infections (BSIs) are not well-characterized. We investigated the epidemiology, antifungal use, susceptibility patterns, and factors associated with all-cause death among cancer patients in whom uncommon Candida spp. BSIs were diagnosed at a cancer treatment center during January 1998–September 2013. Of 1,395 Candida bloodstream isolates, 79 from 68 patients were uncommon Candida spp. The incidence density of uncommon Candida spp. BSIs and their proportion to all candidemia episodes substantively increased during the study period, and the rise was associated with increasing use of echinocandin antifungal drugs. Thirty-seven patients had breakthrough infections during therapy or prophylaxis with various systemic antifungal drugs for >7 consecutive days; 21 were receiving an echinocandin. C. kefyr (82%), and C. lusitaniae (21%) isolates frequently showed caspofungin MICs above the epidemiologic cutoff values. These findings support the need for institutional surveillance for uncommon Candida spp. among cancer patients.

Uncommon opportunistic fungal infections of oral cavity: A review

The majority of opportunistic oral mucosal fungal infections are due to Candida albicans and Aspergillus fumigatus species. Mucor and Cryptococcus also have a major role in causing oral infections, whereas Geotrichum, Fusarium, Rhodotorula, Saccharomyces and Penicillium marneffei are uncommon pathogens in the oral cavity. The broad spectrum of clinical presentation includes pseudo-membranes, abscesses, ulcers, pustules and extensive tissue necrosis involving bone. This review discusses various uncommon opportunistic fungal infections affecting the oral cavity including their morphology, clinical features and diagnostic methods.

Coevolution of morphology and virulence in Candida species

Many of the major human fungal pathogens are known to undergo morphological changes, which in certain cases are associated with virulence. Although there has been an intense research focus on morphology in fungi, very little is known about how morphology evolved in conjunction with a variety of other virulence properties. However, several recent important discoveries, primarily in Candida species, are beginning to shed light on this important area and answer many longstanding questions. In this minireview, we first provide a description of the major fungal morphologies, as well as the roles of morphology and morphology-associated gene expression in virulence. Next, focusing largely on Candida species, we examine the evolutionary relationships among specific morphological forms. Finally, drawing on recent findings, we begin to address the question of how specific morphological changes came to be associated with virulence of Candida species during evolution.

In vitro activity of seven systemically active antifungal agents against a large global collection of rare Candida species as determined by CLSI broth microdilution methods

Five Candida species (C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, and C. krusei) account for over 95% of invasive candidiasis cases. Some less common Candida species have emerged as causes of nosocomial candidiasis, but there is little information about their in vitro susceptibilities to antifungals. We determined the in vitro activities of fluconazole, voriconazole, posaconazole, amphotericin B, anidulafungin, caspofungin, and micafungin against invasive, unique patient isolates of Candida collected from 100 centers worldwide between January 2001 and December 2007. Antifungal susceptibility testing was performed by the CLSI M27-A3 method. CLSI breakpoints for susceptibility were used for fluconazole, voriconazole, anidulafungin, caspofungin, and micafungin, while a provisional susceptibility breakpoint of < or = 1 microg/ml was used for amphotericin and posaconazole. Of 14,007 Candida isolates tested, 658 (4.7%) were among the less common species. Against all 658 isolates combined, the activity of each agent, expressed as the MIC50/MIC90 ratio (and the percentage of susceptible isolates) was as follows: fluconazole, 1/4 (94.8%); voriconazole, 0.03/0.12 (98.6%); posaconazole, 0.12/0.5 (95.9%); amphotericin, 0.5/2 (88.3%); anidulafungin, 0.5/2 (97.4%); caspofungin, 0.12/0.5 (98.0%); and micafungin, 0.25/1 (99.2%). Among the isolates not susceptible to one or more of the echinocandins, most (68%) were C. guilliermondii. All isolates of the less common species within the C. parapsilosis complex (C. orthopsilosis and C. metapsilosis) were susceptible to voriconazole, posaconazole, anidulafungin, caspofungin, and micafungin. Over 95% of clinical isolates of the rare Candida species were susceptible to the available antifungals. However, activity did vary by drug-species combination, with some species (e.g., C. rugosa and C. guilliermondii) demonstrating reduced susceptibilities to commonly used agents such as fluconazole and echinocandins.

Fungemia due to Candida guilliermondii in a pediatric and adult population during a 12-year period

Candida guilliermondii fungemia is usually described in adults with hematologic malignancies, but in children, only 2 episodes have been published. From 1995 to 2006, 7 episodes (5 in children) were detected in our hospital. Molecular typing excluded a common infection source. C. guilliermondii fungemia may occur in children with underlying conditions other than cancer.

Candida guilliermondii fungemia in patients with hematologic malignancies

The microbiological, clinical, and epidemiological features of most non-Candida albicans Candida species are well known, but much less is known about species such as Candida guilliermondii, an uncommon pathogen causing a variety of deep-seated infections in immunocompromised hosts. To characterize C. guilliermondii fungemia in patients with hematological malignancies and its susceptibility to antifungal drugs, all cases of C. guilliermondii fungemia diagnosed in our department between 1983 and 2005 were retrospectively analyzed and the literature was reviewed. C. guilliermondii caused 29/243 (11.7%) candidemia episodes diagnosed during the study period. Central venous catheters were the documented sources of candidemia in 19/29 episodes (65.5%), and invasive tissue infections were documented in 2 (6.9%). In the remaining eight, the catheter was not removed and the source of the fungemia remained obscure. Seven episodes ended in death, but only one could be attributed to invasive C. guilliermondii infection. Molecular typing data reveal no evidence of common infection sources. Isolates displayed high rates of in vitro susceptibility to amphotericin B (100%), voriconazole (95%), and fluconazole (90%) and lower rates of in vitro susceptibility to flucytosine (86%), itraconazole (76%), and caspofungin (33%). Our literature review confirms that C. guilliermondii is a significantly more frequent cause of candidemia among cancer patients compared with the general hospital population. It accounted for <1% of the total number of Candida bloodstream isolates reported in the articles we reviewed, with higher rates in Europe (1.4%) and Asia (1.8%) compared with North America (0.3%).

Candida guilliermondii as the aetiology of candidosis

Candida guilliermondii is one of the components of human microbiota. This yeast has been infrequently associated with human infections, which may be related to its low pathogenicity. The aim of this study was to provide clinical and epidemiological data for patients infected with C. guilliermondii at Santa Casa Complexo Hospitalar, Brazil. From October 1997 to October 2003, C. guilliermondii was isolated from clinical samples from 11 patients. Three patients were excluded because the isolation of the yeast represented colonisation. Specimens from the eight patients included in the study corresponded to blood (n = 5), ascitis fluid (n = 2), and oesophagus biopsy (n = 1). Three patients (37.5%) had major immunosuppressed conditions, including solid organ transplantation, AIDS, and leukaemia. Previous use of antibiotics occurred in 87.5%. Main invasive medical procedures were central venous catheter (50.0%), abdominal surgery (25.0%), and peritoneal dialysis (50.0%). No susceptibility data was obtained. Although risk factors for candidaemia were similar amongst patients infected by with C. guilliermondii or other Candida species, mortality associated with C. guilliermondii was significantly lower.

Vulvovaginal candidiasis in a Flemish patient population

Increased resistance to fluconazole has been reported in oral, oesophageal and urinary Candida isolates, but this has not been observed commonly in genital tract isolates. The rate of isolation of Candida spp. and their susceptibility to amphotericin B, flucytosine and azoles were determined in a number of clinical practices in the city of Ghent, Belgium. Patients with symptomatic vulvovaginal candidiasis (VVC) were treated with fluconazole, and the mycological and clinical outcomes were evaluated. Isolates were identified as Candida albicans (78.6%), Candida guilliermondii (17.3%), Candida glabrata (2.6%) and Candida dubliniensis (1.3%). The rates of mycological and clinical cures were 79.5% and 100%, respectively. Women with recurrent VVC were infected more frequently by non-albicans Candida spp., but no association was found between the use of antifungal agents and the presence of non-albicans spp. In-vitro resistance to fluconazole was not detected, even among subsequent Candida isolates from nine patients for whom mycological cure was not achieved.

Distribution and antifungal susceptibility of Candida species causing candidemia from 1996 to 1999

Susceptibilities to amphotericin B and fluconazole of 383 Candida species isolated from blood were determined. Candida albicans was the most common species (55.6%), followed by Candida parapsilosis (17.5%), Candida tropicalis (16.5%), Candida glabrata (5.2%), Candida guilliermondii (2.3%), and others (2.9%). All but three isolates, Candida ciferrii, C. tropicalis, and C. glabrata, one each, were susceptible to amphotericin B. A total of 367 (95.8%) and 15 (4.2%) isolates were susceptible and susceptible-dose dependent to fluconazole, respectively. Only one isolate, a C. glabrata, was resistant to fluconazole. Few patients (13%) having prior fluconazole treatments may explain the low rate of resistance to fluconazole in this study.

Changing spectrum of invasive candidiasis and its therapeutic implications

Emerging trends in invasive candidiasis are notable for a dramatic increase in infections due to non-albicans Candida species. An increasing number of immunocompromised patients at risk from fungal infections, an overall greater acuity of illness in the hospitalized patients, particularly those in the critical care units, escalating rates of broad-spectrum antibiotic usage, and wide utilization of azoles as prophylaxis have probably contributed towards the changing epidemiology of invasive candidiasis. Given the inherent decreased susceptibility of many of the non-albicans Candida species to currently available antifungal agents, these evolving trends have far-reaching clinical relevance.

[Antifungal susceptibility of emerging yeast pathogens]

BACKGROUND

To study the antifungal susceptibility of emerging yeast pathogens to know their possible resistance under the need of applying a treatment.

MATERIAL AND METHODS

We investigated the in vitro susceptibility of 69 yeast strains isolates of clinical samples, belonging to 24 different species, to amphotericin B, fluconazole, itraconazole, ketoconazole and 5-fluorocytosine.

RESULTS

Only 9 species showed susceptibility to all antifungal agents: Candida famata, C. guillermondii, C. holmii, C. kefyr, C. pelliculosa, C. rugosa, C. utilis, C. zeylanoides y Trichosporon cutaneum; the rest of them presented resistance to some antifungal agent. C. haemulonii, Pichia farinosa and Trichosporon mucoides were resistant to amphotericin B; C. haemulonii, C. inconspicua, C. lusitaniae, C. norvegensis, C. pintolepesii, C. valida, P. ohmeri, Rhodotorula glutinis, R. minuta, R. mucilaginosa and Saccharomyces cerevisiae were resistant to azoles; Blastoschizomyces capitatus and C. lipolytica were resistant to 5-fluorocytosine.

CONCLUSIONS

The resistance of emerging yeast pathogens to amphotericin B and 5-fluorocytosine is low, while resistance to azoles is significative, especially to fluconazole (36%). Many of this yeasts present problems of intrinsic resistance. In yeast infections, the correct identification of species and the study of the in vitro susceptibility is important in order to choose the most adequate antifungal treatment.