Nosocomial cluster of Candida lipolytica fungemia in pediatric patients

Emerging trends of invasive yeast infections and azole resistance in Beijing intensive care units

BACKGROUND

Invasive fungal infections pose a substantial threat to patients in healthcare settings globally. Recent changes in the prevalence of fungal species and challenges in conducting reference antifungal susceptibility testing emphasize the importance of monitoring fungi and their antifungal resistance.

METHODS

A two-phase surveillance project was conducted in Beijing, China, involving 37 centres across 12 districts, from January 2012 to December 2013 and from January 2016 to December 2017.

FINDINGS

We found that the proportion of Candida albicans in intensive care units (ICUs) during 2016-2017 exhibited a significant decline compared with the 2012-2013 period, although it remained the most predominant pathogen. In contrast, the prevalence of Nakaseomyces glabratus (formerly Candida glabrata) and Candida tropicalis notably increased during the two-phase surveillance. The high prevalence of C. tropicalis and its resistance to azole drugs posed a serious threat to patients in ICUs. The pathogens causing invasive fungal infections in Beijing were relatively sensitive to echinocandins. While C. albicans continued to exhibit susceptibility to azoles, the resistance and growth rates of C. tropicalis towards azoles were particularly prominent. Concerns were raised due to the emergence of multiple, short-term isolates of Clavispora lusitaniae and Candida parapsilosis complex in neonatal ICUs, given their similarity in antifungal susceptibilities. Such occurrences point towards the potential for transmission and persisting presence of these pathogens within the ICU environment.

CONCLUSIONS

Our study complements existing data on the epidemiology of invasive fungal infections. It is imperative to exercise cautious medication management for ICU patients in Beijing, paying particular attention to azole resistance in C. tropicalis.

Antifungal susceptibility profile and local epidemiological cut-off values of Yarrowia (Candida) lipolytica: an emergent and rare opportunistic yeast

IMPORTANCE

Yarrowia lipolytica, also known as Candida lipolytica, is an emerging opportunistic "rare pathogenic yeast". Due to the limited data on its antifungal susceptibility, the clinical treatments become challenging. Based on the China Hospital Invasive Fungal Surveillance Network (2009-2022), we conducted a comprehensive multi-method study on clinical isolates from various central hospitals. This study is currently the largest study carried out to assess the antifungal susceptibility of Y. lipolytica. It is also the first to establish local epidemiological cut-off values (L-ECOFFs), identify its ERG11 mutations, and assess the consistency between the three prevalent commercial antifungal susceptibility testing methods and the broth microdilution method. We recommend the Sensititre YeastOne as the best option for antifungal susceptibility testing for Y. lipolytica, followed by the ATB FUNGUS 3. Nevertheless, practitioners should use the MIC test strip with discretion.

Candida lipolytica Bloodstream Infection in an Adult Patient with COVID-19 and Alcohol Use Disorder: A Unique Case and a Systematic Review of the Literature

Candida lipolytica is an uncommon Candida species causing invasive fungemia. This yeast is mainly associated with the colonisation of intravascular catheters, complicated intra-abdominal infections, and infections in the paediatric population. Here, we report a case of C. lipolytica bloodstream infection in a 53-year-old man. He was admitted for an alcohol withdrawal syndrome and mild COVID-19. Among the primary risk factors for candidemia, only the use of broad-spectrum antimicrobials was reported. The empiric treatment was commenced with caspofungin and then targeted with intravenous fluconazole. Infective endocarditis was ruled out using echocardiography, and PET/TC was negative for other deep-seated foci of fungal infection. The patient was discharged after blood culture clearance and clinical healing. To the best of our knowledge, this is the first case of C. lipolytica candidemia in a patient with COVID-19 and alcohol use disorder. We performed a systematic review of bloodstream infections caused by C. lipolytica. Clinicians should be aware of the possibility of C. lipolytica bloodstream infections in patients with alcohol use disorder, especially in a COVID-19 setting.

Distribution Analysis of Candida albicans according to Sex and Age in Clinical Specimen Testing for Sexually Transmitted Diseases

The prevalence of candidiasis, a contagious disease with high morbidity and mortality, has sharply increased globally over the last two decades. Candida albicans can cause serious infections in patients with weak immunity and in recipients of prolonged antibiotic treatment. Consequently, rapid and accurate identification of species can play an important role in the treatment of candidiasis. Here, we investigated the positive rate and infection trend of Candida albicans according to age, specimen type, and sex using multiplex real-time polymerase chain reactionbased testing of samples collected for the diagnosis of sexually transmitted diseases in Korea between 2018 and 2020. When the type of specimen collected was a swab, the positive rate of Candida albicans was higher among younger women, and tended to decrease with age. Analysis of swab samples revealed higher positive rates than urinalysis. The reduction trend in positive rates by age was comparable between the overall samples and urine specimens. Among male patients, the positive rate did not differ substantially across the various types of specimens collected. Previous studies have shown a higher prevalence of non-albicans Candida species than Candida albicans in clinical specimens, and exclusion of the former from our analysis may be a limitation of this study. However, our findings contribute significantly to the literature because globally, there is a paucity of epidemiological studies using molecular techniques to detect Candida albicans in sexually transmitted disease test samples.

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.

Rare Invasive Yeast Infections in Greek Neonates and Children, a Retrospective 12-Year Study

Although Candida species remain the leading cause of invasive fungal infections (IFI), the list of other isolated fungal pathogens is increasing. The aim of the study was to report cases of IFI caused by rare yeasts in the largest tertiary Greek pediatric hospital. A retrospective study was performed from 6/2008–6/2020 regarding IFI caused by rare species. Identification of isolates was attained by conventional, molecular, and MALDI TOF MS methods, and susceptibility testing was performed according to the Clinical and Laboratory Standards (CLSI) methodology. During a 12-year period, 14 different rare fungal species in 33 neonates and children with IFI hospitalized in intensive care and oncology units were isolated from blood, central catheters, peritoneal, pleural, or pericardial fluid specimens. It is the first time for IFI caused by Wickerhamomyces anomalus (Candida pelliculosa), Pichia fermentans (Candida lambica), Yarrowia (Candida) lipolytica, Pichia (Hansenula) kluyveri, Rhodotorula mucilaginosa, Wickerhamiella (Candida) pararugosa and Cyberlindnera (Candida) fabianii in Greek neonates and children to be reported. For most of these rare fungal species isolated in the present study, no official antifungal breakpoints have been defined, and there are no guidelines for their treatment. Clinical laboratories should be aware of uncommon and emerging yeast pathogens and be able to detect them with molecular and proteomic methods.

Scientific Opinion on the update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA (2017-2019)

The qualified presumption of safety (QPS) was developed to provide a safety pre-assessment within EFSA for microorganisms. Strains belonging to QPS taxonomic units (TUs) still require an assessment based on a specific data package, but QPS status facilitates fast track evaluation. QPS TUs are unambiguously defined biological agents assessed for the body of knowledge, their safety and their end use. Safety concerns are, where possible, to be confirmed at strain or product level, and reflected as 'qualifications'. Qualifications need to be evaluated at strain level by the respective EFSA units. The lowest QPS TU is the species level for bacteria, yeasts and protists/algae, and the family for viruses. The QPS concept is also applicable to genetically modified microorganisms used for production purposes if the recipient strain qualifies for the QPS status, and if the genetic modification does not indicate a concern. Based on the actual body of knowledge and/or an ambiguous taxonomic position, the following TUs were excluded from the QPS assessment: filamentous fungi, oomycetes, streptomycetes, Enterococcus faecium, Escherichia coli and bacteriophages. The list of QPS-recommended biological agents was reviewed and updated in the current opinion and therefore now becomes the valid list. For this update, reports on the safety of previously assessed microorganisms, including bacteria, yeasts and viruses (the latter only when used for plant protection purposes) were reviewed, following an Extensive Literature Search strategy. All TUs previously recommended for 2016 QPS list had their status reconfirmed as well as their qualifications. The TUs related to the new notifications received since the 2016 QPS opinion was periodically evaluated for QPS status in the Statements of the BIOHAZ Panel, and the QPS list was also periodically updated. In total, 14 new TUs received a QPS status between 2017 and 2019: three yeasts, eight bacteria and three algae/protists.

Yarrowia lipolytica: a beneficious yeast in biotechnology as a rare opportunistic fungal pathogen: a minireview

Yarrowia lipolytica is one of the most studied "non-conventional" yeast species capable of synthesizing a wide group of valuable metabolites, in particular lipases and other hydrolytic enzymes, microbial oil, citric acid, erythritol and γ-decalactone. Processes based on the yeast have GRAS status ("generally recognized as safe") given by Food and Drug Administration. The majority of research communications regarding to Y. lipolytica claim that the yeast species is non-pathogenic. In spite of that, Y. lipolytica, like other fungal species, can cause infections in immunocompromised and critically ill patients. The yeast possess features that facilitate invasion of the host cell (particularly production of hydrolytic enzymes), as well as the protection of the own cells, such as biofilm formation. The aim of this study was to present well-known yeast species Y. lipolytica as a rare opportunistic fungal pathogen. Possible pathogenicity and epidemiology of this yeast species were discussed. Antifungal drugs susceptibility and increasing resistance to azoles in Y. lipolytica yeasts were also presented.

Update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 8: suitability of taxonomic units notified to EFSA until March 2018

The qualified presumption of safety (QPS) was developed to provide a harmonised generic pre‐evaluation procedure to support safety risk assessments of biological agents performed by EFSA's Scientific Panels. The identity, body of knowledge, safety concerns and antimicrobial resistance of valid taxonomic units were assessed. Safety concerns identified for a taxonomic unit are, where possible and reasonable in number, reflected by ‘qualifications’ which should be assessed at the strain level by the EFSA's Scientific Panels. During the current assessment, no new information was found that would change the previously recommended QPS taxonomic units and their qualifications. The Panel clarified that the qualification ‘for production purpose only’ implies the absence of viable cells of the production organism in the final product and can also be applied for food and feed products based on microbial biomass. Between September 2017 and March 2018, the QPS notification list was updated with 46 microorganisms from applications for market authorisation. From these, 28 biological agents already had QPS status, 15 were excluded of the QPS exercise from the previous QPS mandate (10 filamentous fungi and one bacteriophage) or from further evaluations within the current mandate (two notifications of Streptomyces spp. and one of Escherichia coli), and one was excluded where confirmatory data for the risk assessment of a plant protection product (PPP) was requested (Pseudomonas sp.). Three taxonomic units were (re)evaluated: Paracoccus carotinifaciens and Paenibacillus lentus had been previously evaluated in 2008 and 2014, respectively, and were now re‐evaluated within this mandate, and Yarrowia lipolytica, which was evaluated for the first time. P. carotinifaciens and P. lentus cannot be granted QPS status due to lack of scientific knowledge. Y. lipolytica is recommended for QPS status, but only for production purpose.

Secular Trends of Candidemia in a Large Tertiary-Care Hospital From 1988 to 2000: Emergence ofCandida parapsilosis

Objective:

To analyze the secular trends of candidemia in a large tertiary-care hospital to determine the overall incidence, as well as the incidence by ward and by species, and to detect the occurrence of outbreaks.

Design:

Retrospective descriptive analysis. Secular trends were calculated using the Mantel-Haenszel test.

Setting:

A large tertiary-care referral center in Spain with a pediatric intensive care unit (ICU) to which more than 500 children with congenital cardiac disease are admitted annually.

Patients:

All patients with candidemia occurring from 1988 to 2000 were included. Cases were identified from laboratory records of blood cultures.

Results:

There were 331 episodes of candidemia. The overall incidence of nosocomial candidemia was 0.6 episode per 1,000 admissions and remained stable throughout the study period (P= .925). The species most frequently isolated wasCandida albicans, but the incidence ofC. parapsilosiscandidemia increased (P= .035). In the pediatric ICU, the incidence ofC. parapsilosiswas 5.6 episodes per 1,000 admissions and it was the predominant species. Outbreaks occurred occasionally in the pediatric ICU, suggesting nosocomial transmission.

Conclusions:

During this 13-year period, the incidence of candidemia remained stable in this hospital, butC. parapsilosisincreased in frequency. Occasional outbreaks of candidemia suggested nosocomial transmission ofCandidaspecies (Infect Control Hosp Epidemiol2005;26:548-552).

Clinical Characteristics, Laboratory Identification, and In Vitro Antifungal Susceptibility of Yarrowia (Candida) lipolytica Isolates Causing Fungemia: a Multicenter, Prospective Surveillance Study

Our case series showed that uncomplicated Yarrowia lipolytica fungemia might be treated with catheter removal alone. The Vitek 2 YST identification (ID) card system, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and internal transcribed spacer and 25S nuclear ribosomal DNA (nrDNA) gene sequencing provided reliable identification. All isolates had low MICs to voriconazole, echinocandins, and amphotericin B.

Fungemia caused by Yarrowia lipolytica

Yarrowia lipolytica is weakly pathogenic yeast, which is rarely isolated from the blood. We report unusual cases of Y. lipolytica fungemia occurred between October 2012 and June 2014 in the intensive care unit (ICU) of the UH Habib Bourguiba Sfax. During this period, 55 cases of Y. lipolytica septicemia were diagnosed. There were 44 men and 11 women (sex ratio = 4).The median age was 43 years. The broad-spectrum antibiotics (100 %), the catheterization (96 %), and the prolonged hospitalization in ICU (91 %) were the main risk factors. Patients were hospitalized in ICU, mostly, for polytraumatism (45.4 %), pneumopathy (9 %), and post-operative complications (7 %). Fever unresponsive to broad-spectrum antibacterial therapy was the predominant sign of infection (83.6 %). Y. lipolytica was isolated in one or several blood cultures (14.5 %) and in the catheter tip culture of nine patients (16.3 %).Treatment was based on intravenous amphotericin B (58.2 %), fluconazole (45.4 %) and/or removal catheter (69 %). Apyrexia or blood cultures sterilization was obtained for 34 patients (61.8 %). Y. lipolytica candidemia is an opportunistic and emerging human yeast pathogen. It can reach to the bloodstream of immunocompromised or critically ill patients during hospitalization through intravascular catheterization. Further clinical data need to be evaluated for formulating management strategies of seriously ill patients infected with uncommon fungal agents.

Potential association of specific Candida parapsilosis genotypes, bloodstream infections and colonization of health workers' hands

Fungal nosocomial infections continue to be a serious problem among hospitalized patients, decreasing quality of life and adding millions of euros to healthcare costs. The aim of this study was to describe the pattern of fungi associated with the hands of healthcare workers and to genotype Candida parapsilosis isolates in order to understand whether their high clinical prevalence stems from endemic nosocomial genotypes or from the real emergence of epidemiologically-unrelated strains. Approximately 39% (50/129) of healthcare workers were positive for yeasts and among 77 different fungal isolates recovered, C. parapsilosis was the most frequent (44/77; 57%). Twenty-seven diverse genotypes were obtained by microsatellite analysis of 42 selected blood and hand isolates. Most of the isolates from hands showed a new, unrelated, genotype, whereas a particular group of closely related genotypes prevailed in blood samples. Some of the latter genotypes were also found on the hands of healthcare workers, indicating a persistence of these clones within our hospital. C. parapsilosis genotypes from the hands were much more heterogeneous than clinical ones, thus reflecting a high genetic diversity among isolates, which is notably unusual and unexpected for this species.

Molecular typing of Candida albicans isolates from hospitalized patients

SUMMARY

Introduction: The majority of nosocomial fungal infections are caused by Candida spp. where C. albicans is the species most commonly identified. Molecular methods are important tools for assessing the origin of the yeasts isolated in hospitals.

Methods: This is a study on the genetic profifiles of 39 nosocomial clinical isolates of C. albicans using two typing methods: random amplifified polymorphic DNA (RAPD) and microsatellite, two different primers for each technique were used.

Results: RAPD provided 10 and 11 different profiles with values for S_AB of 0.84 ± 0.126 and 0.88 ± 0.08 for primers M2 and P4, respectively. Microsatellite using two markers, CDC3 and HIS3, allowed the observation of six and seven different alleles, respectively, with combined discriminatory power of 0.91.

Conclusions: Although genetic variability is clear, it was possible to identify high similarity, suggesting a common origin for at least a part of isolates. It is important to emphasize that common origin was proven from yeasts isolated from colonization (urine, catheter or endotracheal secretions) and blood culture from the same patient, indicating that the candidemia must have started from a site of colonization. The combination of RAPD and microsatellite provides a quick and efficient analysis for investigation of similarity among nosocomial isolates of C. albicans.

Yarrowia lipolytica: safety assessment of an oleaginous yeast with a great industrial potential

Yarrowia lipolytica has been developed as a production host for a large variety of biotechnological applications. Efficacy and safety studies have demonstrated the safe use of Yarrowia-derived products containing significant proportions of Yarrowia biomass (as for DuPont's eicosapentaenoic acid-rich oil) or with the yeast itself as the final product (as for British Petroleum's single-cell protein product). The natural occurrence of the species in food, particularly cheese, other dairy products and meat, is a further argument supporting its safety. The species causes rare opportunistic infections in severely immunocompromised or otherwise seriously ill people with other underlying diseases or conditions. The infections can be treated effectively by the use of regular antifungal drugs, and in some cases even disappeared spontaneously. Based on our assessment, we conclude that Y. lipolytica is a "safe-to-use" organism.

Virulence attributes and genetic variability of oral Candida albicans and Candida tropicalis isolates

The wide spectrum of candidiasis and its clinical importance encourage the research with the purpose of clarifying the mechanisms of pathogenicity and identification of virulence factors of Candida sp. Therefore, the aim of this study was to verify the adhesion capacity, protease activity and genotypic diversity of oral C. albicans and C. tropicalis isolates. The adhesion ability to the extracellular matrix glycoproteins laminin and fibronectin was evaluated using the ELISA technique. The research of proteases was carried out in agar plate containing bovine albumin and through a quantitative method in buffer solution containing haemoglobin. Intra and interspecies polymorphisms was verified through random amplified polymorphic DNA (RAPD) technique. All C. albicans and C. tropicalis isolates binded to immobilised laminin and fibronectin. Ca33 and Ct13 isolates had relative adhesion index significantly higher than the other isolates for both glycoproteins (P < 0.001). Protease activity was observed in all isolates of C. albicans using either the semi-quantitative or quantitative assay. The protease activity of C. tropicalis was better detected through the quantitative assay. The genotypic diversity by RAPD revealed a heterogeneous population in both species. Nevertheless, C. tropicalis presented higher genetic variability than C. albicans strains.

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 caused by Candida lipolytica: Speaking of two cases]

Candida lipolytica has rarely been reported as a human pathogen. We observed two cases of fungemia caused by C. lipolytica, one of them in a 12-year-old child with cystic pancreatic fibrosis in advanced phase and another in a 86-year-old woman who presented vesical neoformation with peritoneal fibrosis, bilateral hydronephrosis and recurrent urinary tract infections. After antifungal treatment and catheter removal, the fungemia appeared to be finished and blood cultures were negative.

Analysis of the strain relatedness of oral Candida albicans in patients with diabetes mellitus using polymerase chain reaction-fingerprinting

To increase our understanding of Candida pathogenicity, the identification of those strains most frequently associated with infections is of paramount importance. Polymerase chain reaction (PCR)-based methods are extremely effective in differentiating and determining reproducibility, they require minimum starting material and are rapid and simple to perform. In this study, the genetic relatedness of Candida albicans was assessed for two geographically different patient groups (London, UK and Parma, Italy) affected by diabetes mellitus. C. albicans samples from the oral cavities of non-diabetic healthy subjects were also examined by PCR fingerprinting to evaluate the possible genetic differences among endogenous strains in individuals with and without diabetes mellitus. PCR fingerprinting, with subsequent phylogenetic analysis of C. albicans isolates from the diabetic patients from London and Italy and from the non-diabetic subjects, revealed that there were significant differences (P < 0.0001) between C. albicans isolates indicative of the distinct ecological niches that occur in the oral cavities of these patient cohorts. The most diverse group comprised the isolates from the diabetic patients in the UK, possibly reflecting the antifungal treatment that these patients had received. Further studies that include isolates from patient cohorts with systemic diseases other than diabetes mellitus, and from more diverse geographic localities are required to explain the relatedness of C. albicans isolates in the mouth.

Caspofungin treatment in two infants with persistent fungaemia due to Candida lipolytica

Candida lipolytica has infrequently been identified as a cause of infection and is associated mostly with vascular catheter-related fungaemia. Patients reported in the literature have been successfully treated with catheter removal or amphotericin B treatment. We report 2 infants with C. lipolytica fungaemia unresponsive to catheter removal and amphotericin B therapy and treated successfully with the addition of caspofungin to amphotericin B.

Identification of medically important yeast species by sequence analysis of the internal transcribed spacer regions

Infections caused by yeasts have increased in previous decades due primarily to the increasing population of immunocompromised patients. In addition, infections caused by less common species such as Pichia, Rhodotorula, Trichosporon, and Saccharomyces spp. have been widely reported. This study extensively evaluated the feasibility of sequence analysis of the rRNA gene internal transcribed spacer (ITS) regions for the identification of yeasts of clinical relevance. Both the ITS1 and ITS2 regions of 373 strains (86 species), including 299 reference strains and 74 clinical isolates, were amplified by PCR and sequenced. The sequences were compared to reference data available at the GenBank database by using BLAST (basic local alignment search tool) to determine if species identification was possible by ITS sequencing. Since the GenBank database currently lacks ITS sequence entries for some yeasts, the ITS sequences of type (or reference) strains of 15 species were submitted to GenBank to facilitate identification of these species. Strains producing discrepant identifications between the conventional methods and ITS sequence analysis were further analyzed by sequencing of the D1-D2 domain of the large-subunit rRNA gene for species clarification. The rates of correct identification by ITS1 and ITS2 sequence analysis were 96.8% (361/373) and 99.7% (372/373), respectively. Of the 373 strains tested, only 1 strain (Rhodotorula glutinis BCRC 20576) could not be identified by ITS2 sequence analysis. In conclusion, identification of medically important yeasts by ITS sequencing, especially using the ITS2 region, is reliable and can be used as an accurate alternative to conventional identification methods.

Fluconazole-resistant pathogens Candida inconspicua and C. norvegensis: DNA sequence diversity of the rRNA intergenic spacer region, antifungal drug susceptibility, and extracellular enzyme production

The opportunistic fungal pathogens Candida inconspicua and C. norvegensis are very rarely isolated from patients and are resistant to fluconazole. We collected 38 strains of the two microorganisms isolated from Europe and Japan, and compared the polymorphism of the rRNA intergenic spacer (IGS) and internal transcribed spacer (ITS) regions, antifungal drug susceptibility, and extracellular enzyme production as a potential virulence factor. While the IGS sequences of C. norvegensis were not very divergent (more than 96.7% sequence similarity among the strains), those of C. inconspicua showed remarkable diversity, and were divided into four genotypes with three subtypes. In the ITS region, no variation was found in either species. Since the sequence similarity of the two species is approximately 70% at the ITS region, they are closely related phylogenetically. Fluconazole resistance was reconfirmed for the two microorganisms but they were susceptible to micafungin and amphotericin B. No strain of either species secreted aspartyl proteinase or phospholipase B. These results provide basal information for accurate identification, which is of benefit to global molecular epidemiological studies and facilitates our understanding of the medical mycological characteristics of C. inconspicua and C. norvegensis.

Morphotypic and genotypic characterization of sequential Candida parapsilosis isolates from an outbreak in a pediatric intensive care unit

Candidemia outbreaks that due to cross-infection are an emerging problem in hospitals. Typing of microorganisms is an essential tool for understanding the epidemiologic aspects of the infection. Techniques based on phenotypic characteristics are inexpensive and easy to perform but are limited by their lack of reproducibility. This study assessed the value of several phenotypic and genotypic techniques that are used in epidemiologic investigations of Candida parapsilosis in clinical practice and used a combination of these methods to analyze outbreak of C. parapsilosis candidemia. Random amplification of polymorphic DNA polymerase chain reaction with several primers was unsatisfactory because it lacked discriminatory power. By simplifying the reading of the morphotypes, we increased their reproducibility for each malt agar and 2,3,5-triphenyltetrazolium media (97% and 90%) and thus their suitability for its use. The combination of electrophoretic karyotype and the simplified morphotypes was rapid and practical to characterize the different clusters involved in the intensive care unit outbreak.

An outbreak of candidemia due to Candida tropicalis in a neonatal intensive care unit

An outbreak of candidemia due to Candida tropicalis involving 16 neonates (gestational age 28-36 weeks) is reported. All infants had received hyperalimentation and at least one course of antibiotics. The commonest clinical manifestations included episodes of acute respiratory distress and lack of response to antibacterial antibiotic therapy. Candida tropicalis was recovered from blood in all the 16 infants and urine cultures were positive in 14 infants. Environmental sampling yielded C. tropicalis from one each of the blankets and mattresses used for neonates. Four of five urinary tract isolates and both environmental isolates genotyped by arbitrarily primed-PCR with several random primers were shown to belong to the same genotype.

British Society for Medical Mycology proposed standards of care for patients with invasive fungal infections

Outcomes for invasive fungal infections have greatly improved in the past decade, and several new antifungal drugs have been or will be licensed in the next few years. Early accurate diagnosis and appropriate treatment have major impact on survival. In a 1995 survey of laboratory practice in the UK for mycology, major disparities were seen, with many laboratories not undertaking even simple diagnostic procedures. Delays in processing and inadequate procedures for handling samples, incomplete or delayed reporting of results, or a combination of these, compromise the care of patients. In randomised trials of antifungal chemotherapy, optimum treatments and good alternatives for others have been defined for some infections. High-quality care requires a multidisciplinary approach to diagnosis and management. In this review, we propose microbiology, histopathology, radiology, and clinical auditing standards, with the evidence base for each reviewed. The standards are absolutes, and, therefore, provide a straightforward basis for improving services to patients if they are all implemented.

Complete glycosylphosphatidylinositol anchors are required in Candida albicans for full morphogenesis, virulence and resistance to macrophages

Glycosylphosphatidylinositol (GPI)-anchored proteins are involved in cell wall integrity and cell-cell interactions. We disrupted the Candida albicans homologue of the Saccharomyces cerevisiae GPI7/LAS21 gene, which encodes a GPI anchor-modifying activity. In the mutant and on solid media, the yeast-to-hyphae transition was blocked, whereas chlamydospore formation was enhanced. However, the morphogenetic switch was normal in liquid medium. Abnormal budding patterns, cytokinesis and cell shape were observed in both liquid and solid media. The cell wall structure was also modified in the mutants, as shown by hypersensitivity to Calcofluor white. In vitro and in vivo assays revealed that the mutant interacted with its host in a modified way, resulting in reduced virulence in mice and reduced survival in the gastrointestinal environment of mice. The mitogen-activated protein (MAP) kinase pathway of macrophages was downregulated by the wild-type cells but not by the DeltaCagpi7 null strains. In agreement with this abnormal behaviour, mutant cells were more sensitive to the lytic action of macrophages. Our results indicate that a functional GPI anchor is required for full hyphal formation in C. albicans, and that perturbation of the GPI biosynthesis results in hypersensitivity to host defences.

Catheter-related candidemia caused by Candida lipolytica in a patient receiving allogeneic bone marrow transplantation

Candida lipolytica was recovered from the blood and the central venous catheter in a patient receiving allogeneic bone marrow transplantation. Two C. lipolytica strains from different geographical areas and the ATCC 9773 strain of C. lipolytica were used as controls. C. lipolytica was identified by standard methods. MICs indicated antifungal susceptibilities to amphotericin B, fluconazole, and itraconazole for all strains. In vitro testing and scanning electron microscopy showed that C. lipolytica was capable of producing large amounts of viscid slime material in glucose-containing solution, likely responsible for the ability of the yeast to adhere to catheter surfaces. Restriction fragment length polymorphisms revealed an identical profile for all clinical isolates, unrelated to those observed for the control strains. This finding suggested the absence of microevolutionary changes in the population of the infecting strain, despite the length of the sepsis and the potential selective pressure of amphotericin B, which had been administered to the patient for about 20 days. The genomic differences that emerged between the isolates and the control strains were indicative of a certain degree of genetic diversity between C. lipolytica isolates from different geographical areas.

Identification of Malassezia species from patient skin scales by PCR-RFLP

OBJECTIVE

This study was aimed at the development of a DNA-based procedure directly applicable to pathological skin scales and at the assessment of its value in rapid laboratory confirmation and identification of each of the seven Malassezia species. These lipophilic basidiomycetous yeasts in predisposed individuals are involved in pityriasis versicolor, seborrheic dermatitis, blepharitis, folliculitis, atopic dermatitis and fungemia. Standard identification procedures to species level are available, but so far no system for direct detection and characterization of Malassezia species in clinical specimens is available.

METHODS

Malassezia DNA was extracted from pathological skin scales by a modified hexadecyltrimethylammonium bromide (CTAB) method and amplified by single and nested polymerase chain reaction (PCR), assays using the general fungal ITS 1/4 and 3/4 primers for amplification of sequences from the Malassezia major ribosomal DNA complex. Restriction fragment length polymorphism (RFLP) analysis of PCR products was used in subsequent species identification. DNA extracted from culture-positive skin scales was also tested by PCR and the RFLP patterns obtained were analyzed.

RESULTS

A total of 36 isolates were tested. Distinct pure culture and skin-scale ITS 3/4 HinfI and AluI restriction patterns differentially identified M. furfur, M. globosa, M. restricta, M. sympodialis, M. pachydermatis, M. obtusa and M. slooffiae. Malassezia DNA was extracted from pathological skin scales and RFLP identified solitary and multiple Malassezia species in the same specimen. Molecular identification was confirmed by cultures and biochemical tests. Concurrent detection and identification of Candida and Yarrowia species was also feasible from skin scales.

CONCLUSION

The proposed method, described for the first time, could provide a sensitive and rapid detection and identification system for Malassezia species, which may be applied to epidemiological surveys and routine practice.

Recurrent self-limited fungemia caused by Yarrowia lipolytica in a patient with acute myelogenous leukemia

Yarrowia lipolytica is a weakly pathogenic yeast that is rarely isolated from the blood. We observed transient recurrent catheter-related fungemia attributable to this organism in a leukemic patient. The fungemia and accompanying fever subsided spontaneously. The data suggest that it might be possible to withhold specific treatment for Y. lipolytica fungemia even in an immunocompromised patient.