Identification and antifungal susceptibility profiles of Kodamaea ohmeri based on a seven-year multicenter surveillance study

Microsatellite markers for genotyping of Kodamaea ohmeri: Demonstrating outbreaks based on a multicenter surveillance study in China

Kodamaea ohmeri, an emerging human pathogen, caused both sporadic and nosocomial infections among immunocompromised people with high mortality. However, there is limited research on the molecular epidemiology of K. ohmeri. A total of fifty microsatellite loci were designed based on K. ohmeri type strain NRRL Y-1932 and three loci were finally selected for microsatellite analysis. Non-duplicated K. ohmeri isolates and strains of other species were collected across China as a part of CHIF-NET program for sensitivity and specificity verification. Antifungal susceptibility was determined using Sensititre YeastOne TM YO10. The three loci (P10, P11 and P26), with a cumulative discriminatory power of 0.98, exhibited a prospective specificity and reproducibility in the PCR of 92 K. ohmeri strains from different hospitals. A total of 54 microsatellite types (MT) were identified and most of them distributed sporadically. However, six strains of MT12 clustered in HZ hospital and were isolated in the same department within two months, indicating a potential outbreak. Of seven isolates exhibited MIC values of >8 mg/L for fluconazole, three isolates from LR hospital shared the same genotype of MT44. Herein, we established a set of microsatellite loci for K. ohmeri, as a rapid and specific tool for genotyping K. ohmeri, and identified several potential clusters. This study will help us better understand the molecular epidemiology of the emerging pathogen K. ohmeri.

Hospital‑acquired pneumonia caused by Kodamaea ohmeri during extracorporeal membrane oxygenation treatment: A case report and literature review

Kodamaea ohmeri (K. ohmeri) is an ascosporogenic species of yeast that belongs to the genus Ascosporogenous and the family of Saccharomycetaceae. It has recently been found to cause various types of infections, particularly in critically ill immunocompromised patients. The present study describes a case of hospital-acquired pneumonia caused by K. ohmeri during veno-arterial extracorporeal membrane oxygenation. The fungal culture turned negative after the administration of caspofungin and amphotericin B. Extracorporeal membrane oxygenation (ECMO) is an adjunctive medical technique that provides temporary cardiopulmonary support for patients. Previous observations have suggested that the immune function of patients will typically decline during the use of ECMO, rendering infection to be one of the main complications of ECMO. K. ohmeri is a rare pathogenic fungus, particularly in immunocompromised individuals with vascular catheters, while amphotericin B is the most common antifungal therapy administered to treat K. ohmeri infections. It is important to raise awareness of rare fungal infections and actively treat them.

Diverse signatures of convergent evolution in cacti-associated yeasts

Many distantly related organisms have convergently evolved traits and lifestyles that enable them to live in similar ecological environments. However, the extent of phenotypic convergence evolving through the same or distinct genetic trajectories remains an open question. Here, we leverage a comprehensive dataset of genomic and phenotypic data from 1,049 yeast species in the subphylum Saccharomycotina (Kingdom Fungi, Phylum Ascomycota) to explore signatures of convergent evolution in cactophilic yeasts, ecological specialists associated with cacti. We inferred that the ecological association of yeasts with cacti arose independently ~17 times. Using machine-learning, we further found that cactophily can be predicted with 76% accuracy from functional genomic and phenotypic data. The most informative feature for predicting cactophily was thermotolerance, which is likely associated with duplication and altered evolutionary rates of genes impacting the cell envelope in several cactophilic lineages. We also identified horizontal gene transfer and duplication events of plant cell wall-degrading enzymes in distantly related cactophilic clades, suggesting that putatively adaptive traits evolved through disparate molecular mechanisms. Remarkably, multiple cactophilic lineages and their close relatives are emerging human opportunistic pathogens, suggesting that the cactophilic lifestyle-and perhaps more generally lifestyles favoring thermotolerance-may preadapt yeasts to cause human disease. This work underscores the potential of a multifaceted approach involving high throughput genomic and phenotypic data to shed light onto ecological adaptation and highlights how convergent evolution to wild environments could facilitate the transition to human pathogenicity.

Four uncommon clinical fungi, Lodderomyces elongisporus, Kodamaea ohmeri, Cyberlindnera fabianii and Wickerhamomyces anomalus, isolated in superficial samples from Côte d'Ivoire

AIMS

The rare yeast species Lodderomyces elongisporus, Kodamaea ohmeri, Cyberlindnera fabianii, and Wickerhamomyces anomalus are increasingly implicated in severe mycoses in immunocompromised patients. This study aimed to assess the prevalence of uncommon yeast species in Côte d'Ivoire.

METHODS

The yeast isolates from superficial samples, mainly vaginal swabs, were collected at the Pasteur Institute of Abidjan in a study on the molecular epidemiology of clinical yeast species. Identification relied on MALDI-TOF MS and ITS sequence analysis. Antifungal susceptibility testing was performed using the CLSI method.

RESULTS

Of the 315 strains analysed from 227 outpatients, 14 belonged to 4 uncommon species: Lodderomyces elongisporus, Kodamaea ohmeri, Cyberlindnera fabianii, and Wickerhamomyces anomalus. None exhibited elevated fluconazole, amphotericin B, caspofungin, ketoconazole, or flucytosin MIC.

CONCLUSIONS

The presence of these rare yeasts represents a risk in immunocompromised people. Their adequate and timely identification is a priority. Overall, enhancing the mycoses diagnostic capacities in Côte d'Ivoire, and more generally in African clinical laboratories with limited resources is a critical aim.

Gut-derived fungemia due to Kodamaea ohmeri combined with invasive pulmonary aspergillosis: a case report

BACKGROUND

Kodamaea ohmeri is a rare pathogen with high mortality and is found among blood samples in a considerable proportion; however, gastrointestinal infection of K. ohmeri is extremely rare. Invasive pulmonary aspergillosis is also an uncommon fungal; these two fungal infections reported concomitantly are unprecedented.

CASE PRESENTATION

We described a case of a 37-year-old male who got infected with K. ohmeri and invasive pulmonary aspergillosis. We used the mass spectrometry and histopathology to identify these two fungal infections separately. For the treatment of K. ohmeri, we chose caspofungin. As for invasive pulmonary aspergillosis, we used voriconazole, amphotericin B, and then surgery. The patient was treated successfully through the collaboration of multiple disciplines.

CONCLUSIONS

We speculate that the destruction of the intestinal mucosa barrier can make the intestine one of the ways for certain fungi to infect the human body.

Kodamaea ohmeri as an Emerging Human Pathogen: A Review and Update

Background: Kodamaea ohmeri, previously known as Pichia ohmeri or Yamadazyma ohmeri, has been regarded as an emerging human pathogen in recent decades, and has caused various types of infections with high mortality. This study systematically reviewed all the published cases of K. ohmeri infection, aiming to have a better understanding of the clinical and epidemiological characteristics of the organism. Methods: All the published literature (as of March 31, 2021) on K. ohmeri, in four databases: PubMed, Embase, Web of Science, and CNKI, were systematically reviewed to select appropriate studies for summarizing the demographic information, clinical and microbiological characteristics of relevant infections. Results: A total of 51 studies involving 67 patients were included for final analysis, including 49 sporadic cases and two clusters of outbreaks. Neonates and the elderly constituted the majority of patients, and fungemia was the dominant infection type. Comorbidities (like malignancy, diabetes, and rheumatism), invasive operations, previous antibiotic use and prematurity, were commonly described in patients. Gene sequencing and broth microdilution method, were the most reliable way for the identification and antifungal susceptibility testing of K. ohmeri, respectively. Amphotericin B and fluconazole were the commonest antifungal therapies administered. The calculated mortality rates for K. ohmeri infection was higher than that of common candidemia. Conclusion: In this study, we systematically reviewed the epidemiology, clinical characteristics, microbiological features, treatment, and outcomes, of all the published cases on K. ohmeri. Early recognition and increased awareness of K. ohmeri as an emerging human pathogen by clinicians and microbiologists is important for effective management of this organism.

Azole Susceptibility Profiles of More than 9,000 Clinical Yeast Isolates Belonging to 40 Common and Rare Species

Invasive yeast infections represent a major global public health issue, and only few antifungal agents are available. Azoles are one of the classes of antifungals used for treatment of invasive candidiasis. The determination of antifungal susceptibility profiles using standardized methods is important to identify resistant isolates and to uncover the potential emergence of intrinsically resistant species. Here, we report data on 9,319 clinical isolates belonging to 40 pathogenic yeast species recovered in France over 17 years. The antifungal susceptibility profiles were all determined at the National Reference Center for Invasive Mycoses and Antifungals based on the EUCAST broth microdilution method. The centralized collection and analysis allowed us to describe the trends of azole susceptibility of isolates belonging to common species, confirming the high susceptibility for Candida albicans (n = 3,295), Candida tropicalis (n = 641), and Candida parapsilosis (n = 820) and decreased susceptibility for Candida glabrata (n = 1,274) and Pichia kudriavzevii (n = 343). These profiles also provide interesting data concerning azole susceptibility of Cryptococcus neoformans species complex, showing comparable MIC distributions for the three species but lower MIC₅₀s and MIC₉₀s for serotype D (n = 208) compared to serotype A (n = 949) and AD hybrids (n = 177). Finally, these data provide useful information for rare and/or emerging species, such as Clavispora lusitaniae (n = 221), Saprochaete clavata (n = 184), Meyerozyma guilliermondii complex (n = 150), Candida haemulonii complex (n = 87), Rhodotorula mucilaginosa (n = 55), and Wickerhamomyces anomalus (n = 36).