First Isolation of Candida nivariensis, an Emerging Fungal Pathogen, in Kuwait

Spectrum and management of rare Candida/yeast infections in Kuwait in the Middle East

Invasive fungal infections (IFIs) are associated with high mortality rates and mostly affect patients with compromised immunity. The incidence of IFIs is increasing worldwide with the expanding population of susceptible patients. Candida and other yeast infections represent a major component of IFIs. Rare Candida/yeast infections have also increased in recent years and pose considerable diagnostic and management challenges as they are not easily recognized by routine phenotypic characteristic-based diagnostic methods and/or by the automated yeast identification systems. Rare Candida/yeasts also exhibit reduced susceptibility to antifungal drugs making proper management of invasive infections challenging. Here, we review the diagnosis and management of 60 cases of rare Candida/yeast IFIs described so far in Kuwait, an Arabian Gulf country in the Middle East. Interestingly, majority (34 of 60, 56.7%) of these rare Candida/yeast invasive infections occurred among neonates or premature, very-low-birth-weight neonates, usually following prior bacteremia episodes. The clinical details, treatment given, and outcome were available for 28 of 34 neonates. The crude mortality rate among these neonates was 32.2% as 19 of 28 (67.8%) survived the infection and were discharged in healthy condition, likely due to accurate diagnosis and frequent use of combination therapy. Physicians treating patients with extended stay under intensive care, on mechanical ventilation, receiving broad spectrum antibiotics and with gastrointestinal surgery/complications should proactively investigate IFIs. Timely diagnosis and early antifungal treatment are essential to decrease mortality. Understanding the epidemiology and spectrum of rare Candida/yeast invasive infections in different geographical regions, their susceptibility profiles and management will help to devise novel diagnostic and treatment approaches and formulate guidelines for improved patient outcome.

Candida nivariensis, an emerging fungus causing peritonitis in a patient receiving peritoneal dialysis

Fungal peritonitis (FP) is usually associated with poor patient outcomes and is mostly caused by non-albicans Candida species. We present a Candida nivariensis-associated peritonitis in a 68-year-old woman with end-stage kidney disease on peritoneal dialysis (PD). Biochemical profiling of the cultured yeast of the effluent sample did not adequately identify the yeast. Hence, molecular phylogeny and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) mass spectroscopy were employed which correctly identified the causative species, C. nivariensis. PD catheter was removed and oral fluconazole was promptly started according to the 2022 International Society for PD (ISPD) Peritonitis Guidelines. However, the patient achieved only a partial clinical response and eventually died. The susceptibility test showed that the pathogen was susceptible to amphotericin B and voriconazole but resistant to other triazoles. This report underlines the importance of identifying the species, though rarely reported, and the drug susceptibility of the organism.

Treatment of Candida nivariensis Blood Stream Infection With Oral Isavuconazole

Candida nivariensis is a rarely isolated yeast that is now considered a species within the Candida glabrata complex. Anti-fungal susceptibilities and treatments of Candida nivariensis are often assessed on a case-by-case basis. In this case, a 70-year-old male with a complex medical history presented to a large academic medical center in the United States for vascular surgery. After surgery, the patient's white blood cell count increased prompting an infectious workup. The patient was found to have a Candida nivariensis bloodstream infection of unknown origin. Given the patient's clinical stability and QTc prolongation, he was treated with a 14-day course of oral isavuconazole. The patient experienced resolution of symptoms and clearance of subsequent blood cultures. At the time of writing this case report (11 months later), he has had no relapse of his fungal infection. Based on a search of the medical literature, this appears to be the first published case of Candida nivariensis fungemia successfully treated with oral isavuconazole.

Refractory esophagitis caused by Candida nivariensis: second description of this yeast in Brazil and a literature review

Candida nivariensis caused refractory esophagitis in a 36-year-old Brazilian man coinfected with HIV and Leishmania. A literature review on this rare fungal pathogen is also presented. The diagnosis was made, and pathogen identification was performed using matrix-assisted laser desorption ionization-time of flight mass spectrometry and sequencing of the LSU/26S region. An antifungigram was performed using broth microdilution. A literature search of PubMed was performed. The causative agent, C. nivariensis, was resistant to fluconazole and voriconazole. The patient's condition worsened considerably, and he passed away. This is the second report of this Candida species in Brazil and the first case reported worldwide of refractory esophagitis in a patient coinfected with HIV and Leishmania. The case illustrates the importance of precise identification and antifungal susceptibility testing when isolating this emerging pathogen.

Candidiasis by Candida glabrata, Candida nivariensis and Candida bracarensis in Galleria mellonella: Virulence and Therapeutic Responses to Echinocandins

Candida albicans is the major etiological agent of invasive candidiasis but the increasing prevalence of emerging species of Candida, such as Candida glabrata and phylogenetically closely related species, Candida nivariensis and Candida bracarensis, requires special attention. Differences in virulence among these species and their therapeutic responses using in vivo non-mammalian models are scarcely analysed. The aim of this study was analyse the survival of G. mellonella and host-pathogen interactions during infection by C. glabrata, C. nivariensis and C. bracarensis. Moreover, therapeutic responses to echinocandins were also assessed in the G. mellonella model of candidiasis. These three species produced lethal infection in G. mellonella; C. glabrata was the most virulent species and C. bracarensis the less. Haemocytes of G. mellonella phagocytised C. bracarensis cells more effectively than those of the other two species. Treatment with caspofungin and micafungin was most effective to protect larvae during C. glabrata and C. nivariensis infections while anidulafungin was during C. bracarensis infection. The model of candidiasis in G. mellonella is simple and appropriate to assess the virulence and therapeutic response of these emerging Candida species. Moreover, it successfully allows for detecting differences in the immune system of the host depending on the virulence of pathogens.