Volume 113, Issue 4, December 2025, 117052Author links open overlay panelHighlights•

Candida kefyr (Kluyveromyces marxianus) is an emerging fungal pathogen in immunosuppresed populations, including transplant recipients.

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Accurate identification by methods such as MALDI-TOF and antifungal susceptibility testing are essential for appropriate management.

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Timely diagnosis and treatment can result in favorable outcomes, with most published cases demonstrating clinical cure

AbstractBackground

Kluyveromyces marxianus, formerly known as Candida kefyr, is an emerging opportunistic yeast increasingly reported in immunocompromised hosts. This review aims to summarize the clinical presentations, diagnostic approaches, treatment strategies, and outcomes of C. kefyr infections among transplantation recipients through an analysis of published case reports. A comprehensive literature search was performed using PubMed, Scopus, and Web of Science for case reports involving transplantation patients infected with C. kefyr. The review included only individual case reports describing invasive fungal infections in solid organ or hematopoietic stem cell transplant recipients. A total of seven case reports were identified. Clinical presentations included fungemia, keratitis and catheter-related bloodstream infections. Median age was 61.0. Most of the case had neutropenia and consumption of dairy products. Also, the ratio of localized organ involvement is higher. C. kefyr should be considered a potential opportunistic pathogen in transplant recipients, particularly in older or neutropenic patients with regular dairy consumption. Early diagnosis and appropriate antifungal therapy are essential for favorable outcomes.

Introduction

Kluyveromyces marxianus, also known by its teleomorph name Candida kefyr, is a non-albicans yeast species [1]. It can be isolated from a wide variety of natural habitats, including fermented traditional dairy products, kefir grain and various plants [2].

C. kefyr is increasingly recognized as an emerging fungal pathogen with a growing number of infections reported in recent years, particularly among immunocompromised individuals, such as those with hematological malignancies [3]. Recent whole-genome sequencing studies have identified the consumption of dairy products such as yogurt or kefir, which contain C. kefyr, as the most likely source of disseminated infection in an immunocompromised patient with mucositis [4].

According to a study in the literature, emerging species like K marxianus isolated from the oral cavity of cancer patients were misidentified when using conventional diagnostic methods [5]. Just as there are challenges in diagnosis, there are also difficulties in treatment. A study conducted in Turkey identified C. kefyr strains that were resistant to amphotericin B [6]. Therefore, among immunosuppressed patients, it is particularly important to establish an accurate diagnosis and initiate appropriate treatment based on antifungal susceptibility testing [7]. This review focuses specifically on published case reports that document infections caused by K. marxianus in transplant patients. By aggregating clinical findings from these reports, we aim to provide an overview of its pathogenic potential, clinical features, antifungal susceptibility, and patient outcomes.

Section snippetsMethodsA structured literature review was conducted using PubMed, Scopus, and Web of Science databases up to May 2025. Search terms included: "Kluyveromyces marxianus", "Candida kefyr", "transplantation", and "case report". Inclusion criteria were:•

Individual case reports involving solid organ transplant (SOT) or hematopoietic stem cell transplant (HSCT) recipients

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Laboratory-confirmed K. marxianus infection

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Articles in English

Exclusion criteria:•

Reviews, editorials, and expert opinions

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Case series with no

Present Case

A 69 year old female patient who had undergone cadaveric renal transplantation (tx) in 2004 was admitted with a 4-day history of dysuria (posttx 3960.day) and nausea with vomiting. At the time of admission, the patient was receiving immunosuppressive therapy with mycophenolic acid and tacrolimus. Urine culture obtained during hospitalization revealed the growth of Vancomycin-resistant Enterococcus faecium (VRE), for which intravenous daptomycin was initiated. Subsequently, C. kefyr was isolated

Results

The literature search initially identified ten potential case reports. After reviewing the titles and abstracts, three were excluded for not meeting the inclusion criteria. With the addition of our patient, a total of seven case reports were reviewed in this study [4,[8], [9], [10]] (Characteristics of included case reports in the review summarized in the Table 1). The patients group consists of four females and three males. Median age is 61.0.

When we focused on the transplantations; two

Discussion

Our knowledge of C. kefyr epidemiology remains limited and is primarily based on individual case reports and small case series. In a central region of Turkey, C. kefyr was isolated from various clinical samples at a rate of 5.3 % in 2016, which increased to 9.3 % in 2017—nearly a two-fold rise—drawing attention to its growing clinical relevance [11]. It has emerged as a notable opportunistic pathogen, with a rising incidence particularly observed in individuals with hematologic malignancies [3

Conclusion

Kluyveromyces marxianus (C. kefyr) should be recognized as a potential opportunistic pathogen in transplant recipients, particularly in older or neutropenic patients, and especially those with regular consumption of dairy products such as kefir or yogurt. Increased awareness, accurate diagnosis, and appropriate antifungal management are critical for optimal outcomes. Additional studies, including surveillance and susceptibility profiling, are necessary to guide clinical practice.

Patient Consent

Written informed consent was obtained from the patient included in our case report for the publication of their clinical details. As this manuscript is partly based on a review of previously published case reports, informed consent could not be obtained for those cases.

Ethical Approval

Written informed consent was obtained from the patient presented in this case

CRediT authorship contribution statement

Yasemin Nadir: Writing – original draft, Methodology, Investigation, Funding acquisition, Formal analysis, Data curation, Conceptualization.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The author declare that they have no competing interests. This research received no external funding.

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