Review of the Current Management of Urinary Tract Infections due to Fluconazole-Resistant and Non-Albicans Candida Species

Distribution and antifungal susceptibility of Candida species causing vulvovaginal candidiasis and urinary tract infection in Medlatec healthcare system, Ha Noi city, Vietnam in 2023

Background

Vulvovaginal candidiasis and urinary tract infections caused by Candida are common diseases. While the most common causative agent is C. albicans, other species, such as non-C. albicans, can also be responsible. Susceptibility to antifungal drugs varies among Candida species, but there is very limited information available from Vietnam.

Objectives

To determine the species distribution and antifungal susceptibility patterns of Candida isolated from urine and vaginal samples of patients tested at the Medlatec healthcare system in 2023.

Design

Cross-sectional study.

Methods

The study describes a cross-sectional analysis of over 102 Candida isolates obtained from urine and vaginal samples of patients using the testing services at Vietnam Medlatec healthcare system from January to December 2023. Species identification of Candida isolates was performed using germ tube test and Vitek® 2 systems. Antifungal susceptibility testing was carried out using the VITEK® 2 card for yeast fungi. Minimum inhibitory concentrations for these isolates were classified according to the Clinical and Laboratory Standards Institute guidelines (M27-A3 and M27M44S-ED3).

Results

In this investigation, five different Candida species were identified. Among these isolates, C. albicans (78.43%) was the most frequent, followed by C. tropicalis (11.76%), C. glabrata (4.91%), C. parapsilosis (1.96%), and C. krusei (0.98%). The resistance rates to fluconazole, voriconazole, caspofungin, micafungin, and amphotericin B were 7.7%, 4.2%, 4.0%, 1.0% and 1.0%, respectively.

Conclusion

The most common species found in this population was C. albicans. Our findings also showed a high frequency of non-albicans Candida species causing fungal urinary tract infections. The resistance rates of isolated Candida strains to echinocandins and amphotericin B were low, while some strains were found to be resistant to fluconazole and voriconazole.

Pichia kudriavzevii (Candida krusei): A systematic review to inform the World Health Organisation priority list of fungal pathogens

In response to the growing global threat of fungal infections, in 2020 the World Health Organisation (WHO) established an Expert Group to identify priority fungi and develop the first WHO fungal priority pathogen list (FPPL). The aim of this systematic review was to evaluate the features and global impact of invasive infections caused by Pichia kudriavzevii (formerly known as Candida krusei). PubMed and Web of Science were used to identify studies published between 1 January 2011 and 18 February 2021 reporting on the criteria of mortality, morbidity (defined as hospitalisation and length of stay), drug resistance, preventability, yearly incidence, and distribution/emergence. Overall, 33 studies were evaluated. Mortality rates of up to 67% in adults were reported. Despite the intrinsic resistance of P. kudriavzevii to fluconazole with decreased susceptibility to amphotericin B, resistance (or non-wild-type rate) to other azoles and echinocandins was low, ranging between 0 and 5%. Risk factors for developing P. kudriavzevii infections included low birth weight, prior use of antibiotics/antifungals, and an underlying diagnosis of gastrointestinal disease or cancer. The incidence of infections caused by P. kudriavzevii is generally low (∼5% of all Candida-like blood isolates) and stable over the 10-year timeframe, although additional surveillance data are needed. Strategies targeting the identified risk factors for developing P. kudriavzevii infections should be developed and tested for effectiveness and feasibility of implementation. Studies presenting data on epidemiology and susceptibility of P. kudriavzevii were scarce, especially in low- and middle-income countries (LMICs). Thus, global surveillance systems are required to monitor the incidence, susceptibility, and morbidity of P. kudriavzevii invasive infections to inform diagnosis and treatment. Timely species-level identification and susceptibility testing should be conducted to reduce the high mortality and limit the spread of P. kudriavzevii in healthcare facilities.

Flucytosine and its clinical usage

Flucytosine is an antifungal agent first licensed in the 1970's. However, its clinical value has long been overlooked and its availability across the globe is limited. This review highlights the important clinical and pharmacological aspects of flucytosine. This a narrative review of the clinical and in vitro susceptibility literature, with a focus on clinical uses for flucytosine. Detailed literature review including early literature related to primary and acquired resistance to flucytosine. Flucytosine has good antifungal activity against Cryptococcus species, Candida species, and dematiaceous fungi. Its water solubility enables good penetration into the eye, urinary tract, central nervous system (CNS), cardiac vegetations and fungal biofilms. In combination with amphotericin B, it shows early fungicidal activity against Cryptococcus species, and this translates to ~20% improved survival in cryptococcal meningitis. Combination therapy also reduces the mortality of Candida meningitis, and should be used in neonatal candidiasis because of the high frequency of CNS infection. Monotherapy for urinary candidiasis is under-studied, but is usually effective. It is probably valuable in the treatment of Candida endocarditis and endophthalmitis: there are few data. It is not effective for aspergillosis or mucormycosis. Flucytosine monotherapy of urinary candidiasis resulted in 22% developing resistance on therapy and failing therapy, and in 29% of 21 patients with cryptococcosis. Certain regions of the world still do not have access to flucytosine compromising the management of certain severe fungal infections. Flucytosine has an important role in combination therapy for yeast and dematiaceous infections and probably as monotherapy for urinary candidiasis, with a modest risk of resistance emergence. Facilitating access to flucytosine in those regions (especially low-income countries) might alleviate the mortality of invasive fungal diseases.