Evaluation of Fluorescent Capillary Electrophoresis for Rapid Identification of Candida Fungal Infections

Antifungal resistance in Candida spp within the intra-abdominal cavity: study of resistance acquisition in patients with serial isolates

OBJECTIVES

Antifungal susceptibility testing is mostly conducted on blood-cultured Candida spp isolates. Because the intra-abdominal cavity has been highlighted as a hidden echinocandin-resistant C. glabrata reservoir, we assessed whether testing sequential isolates from a given patient might increase the chances of detecting antifungal resistance.

METHODS

Intra-abdominal initial and sequential isolates from the same species from patients included in the CANDIdaemia in MADrid study (January 2019 to June 2022) were studied. We assessed antifungal susceptibility to amphotericin B, azoles, anidulafungin, micafungin, and ibrexafungerp using European Committee on Antimicrobial Susceptibility Testing (EUCAST) methodology and molecularly characterized resistant isolates.

RESULTS

We collected 308 isolates (C. albicans [n = 179/308; 58.1%], C. glabrata [n = 101/308; 32.8%], C. tropicalis [n = 17/308; 5.5%], and C. parapsilosis [n = 11/308; 3.6%]) from 112 patients distributed as incident (n = 125/308) and sequential (n = 183/308). Per patient resistance rates of fluconazole (13.4% [15/112] vs. 8% [9/112]); 5.4% proportions difference (95% CI, -2.7% to 13.5%, p 0.09) and echinocandins (8.9% [10/112] vs. 1.8% [2/112]); 7.1% proportions difference (95% CI; 1.2-12.9%; p 0.01) were higher when considering all available isolates than only incident isolates. Resistance was detected in 18 of 112 patients and would have been overlooked in 11 of 18 (61.1%) patients if only incident isolates had been studied. Of the patients who harboured fluconazole or echinocandin-resistant isolates, 14 of 15 and 8 of 10 had received or were receiving fluconazole or echinocandins, respectively.

DISCUSSION

Testing sequential Candida isolates from intra-abdominal samples is required to detect antifungal resistance, particularly to echinocandins, in patients whose incident isolates turned out to be susceptible. Furthermore, patients with echinocandin-resistant infections had frequently used echinocandins and had common secondary resistance acquisition.

Blood and intra-abdominal Candida spp. from a multicentre study conducted in Madrid using EUCAST: emergence of fluconazole resistance in Candida parapsilosis, low echinocandin resistance and absence of Candida auris

OBJECTIVES

We prospectively monitored the epidemiology and antifungal susceptibility of Candida spp. from blood cultures and intra-abdominal samples in patients admitted to hospitals in the Madrid area.

METHODS

Between 2019 and 2021, we prospectively collected incident isolates [one per species, patient and compartment (blood cultures versus intra-abdominal samples)] from patients admitted to any of 16 hospitals located in Madrid. We studied the antifungal susceptibilities to amphotericin B, triazoles, micafungin, anidulafungin and ibrexafungerp following the EUCAST E.Def 7.3.2 procedure.

RESULTS

A total of 2107 Candida spp. isolates (1895 patients) from blood cultures (51.7%) and intra-abdominal samples were collected. Candida albicans, the Candida glabrata complex, the Candida parapsilosis complex, Candida tropicalis and Candida krusei accounted for 96.9% of the isolates; in contrast, Candida auris was undetected. Fluconazole resistance in Candida spp. was higher in blood cultures than in intra-abdominal samples (9.1% versus 8.2%; P > 0.05), especially for the C. parapsilosis complex (16.6% versus 3.6%, P < 0.05), whereas echinocandin resistance tended to be lower in blood cultures (0.5% versus 1.0%; P > 0.05). Resistance rates have risen, particularly for fluconazole in blood culture isolates, which increased sharply in 2021. Ibrexafungerp showed in vitro activity against most isolates. Species distributions and resistance rates varied among hospitals.

CONCLUSIONS

Whereas no C. auris isolates were detected, fluconazole-resistant C. parapsilosis isolates have been spreading across the region and this has pulled up the rate of fluconazole resistance. In contrast, the rate of echinocandin resistance continues to be low.

Evidence of Fluconazole-Resistant Candida parapsilosis Genotypes Spreading across Hospitals Located in Madrid, Spain and Harboring the Y132F ERG11p Substitution

We have been monitoring the antifungal resistance in Candida parapsilosis isolates collected from inpatients at Madrid metropolitan area hospitals for the last 3 years. The study aimed to elucidate the presence of fluconazole-resistant C. parapsilosis genotypes in Madrid. From January 2019 to December 2021, a total of 354 C. parapsilosis isolates (n = 346 patients) from blood (76.6%) or intraabdominal samples were collected and genotyped using species-specific microsatellite markers. Antifungal susceptibilities to amphotericin B, the triazoles, micafungin, anidulafungin, and ibrexafungerp were performed according to EUCAST E.Def 7.3.2; the ERG11 gene was sequenced in fluconazole-resistant isolates. A total of 13.6% (n = 48/354) isolates (one per patient) were found to be resistant to fluconazole and non-wild-type to voriconazole but fully susceptible to ibrexafungerp. Resistant isolates were mostly sourced from blood (n = 45/48, 93.8%) and were detected in five hospitals. Two hospitals accounted for a high proportion of resistant isolates (n = 41/48). Resistant isolates harbored either the Y132F ERG11p amino acid substitution (n = 43) or the G458S substitution (n = 5). Isolates harboring the Y132F substitution clustered into a clonal complex involving three genotypes (one genotype accounted for n = 39/43 isolates) that were found in four hospitals. Isolates harboring the G458S substitution clustered into another genotype found in a fifth hospital. C. parapsilosis genotypes demonstrating resistance to fluconazole have been spreading across hospitals in Madrid, Spain. Over the last 3 years, the frequency of isolation of such isolates and the number of hospitals affected is on the rise.

Fluorescent toys 'n' tools lighting the way in fungal research

Although largely overlooked compared to bacterial infections, fungal infections pose a significant threat to the health of humans and other organisms. Many pathogenic fungi, especially Candida species, are extremely versatile and flexible in adapting to various host niches and stressful situations. This leads to high pathogenicity and increasing resistance to existing drugs. Due to the high level of conservation between fungi and mammalian cells, it is hard to find fungus-specific drug targets for novel therapy development. In this respect, it is vital to understand how these fungi function on a molecular, cellular as well as organismal level. Fluorescence imaging allows for detailed analysis of molecular mechanisms, cellular structures and interactions on different levels. In this manuscript, we provide researchers with an elaborate and contemporary overview of fluorescence techniques that can be used to study fungal pathogens. We focus on the available fluorescent labelling techniques and guide our readers through the different relevant applications of fluorescent imaging, from subcellular events to multispecies interactions and diagnostics. As well as cautioning researchers for potential challenges and obstacles, we offer hands-on tips and tricks for efficient experimentation and share our expert-view on future developments and possible improvements.

Candida africana vulvovaginitis: Prevalence and geographical distribution

Candida africana has been recovered principally as a causative agent of vulvovaginal candidiasis (VVC) from different countries, which is likely to be misidentified as the typical Candida albicans or Candida dubliniensis. The current study aimed to characterize C. albicans species complex obtained from VVC based on conventional and molecular assays. Furthermore, in vitro antifungal susceptibility testing was performed based on CLSI documents. Additionally, due to low knowledge concerning C. africana infections, we reviewed all published papers from 1991 to 2019. One hundred forty-four out of 287 patients were identified with Candida infection, among whom 151 isolates of Candida were obtained. Candida albicans 109 (72.1%), Candida glabrata 21 (13.9%), Candida krusei 8 (5.2%), Candida tropicalis 5 (3.3%), Candida africana 3 (1.9%), Candida parapsilosis 3 (1.9%) and C. dubliniensis 2 (1.3%) were isolated from patients. MIC results showed that C. africana isolates were susceptible to all tested antifungal drugs. Candida africana infections were more prevalent in Africa. One hundred fifteen (40.6%) of patients with C. africana candidiasis were from seven African countries, and Madagascar and Angola had the majority of cases. The epidemiological data, phenotypic, clinical features, ecologic similarity, and antifungal susceptibility profiles for better understanding of the pathogenic mechanisms and optimal treatment underlying non-CandidaalbicansCandida vulvovaginitis are highly recommended.

Fluorescent Capillary Electrophoresis Is Superior to Culture in Detecting Candida Species from Samples of Urinary Catheters and Ureteral Stents with Mono- or Polyfungal Biofilm Growth

Molecular techniques in fungal detection and identification represent an efficient complementary diagnostic tool which is increasingly used to overcome limitations of routinely used culture techniques. The aim of this study was to characterize Candida sp. representation in samples from urine, urinary catheter, and ureteral stent biofilm using ITS2 ribosomal DNA (rDNA) amplification followed by fluorescent capillary electrophoresis (f-ITS2-PCR-CE) and to compare the results with those obtained by culture. A total of 419 samples were analyzed, and 106 (25.2%) were found positive, out of which 17 (16%) were polyfungal. The positivity rate did not differ between samples from catheters and stents (23.6% versus 20.9%) or between catheter and stent corresponding urine samples (40.2% versus 30.2%). Ten different Candida species were detected, with Candida parapsilosis (31.4%), Candida albicans (26.5%), and Candida tropicalis (12.4%) predominating. f-ITS2-PCR-CE was evaluated as substantially less time-consuming and 8.3 times more sensitive than the routinely applied culture technique with 1 µl of urine/sonicated fluid inoculated, detecting 67 (19.9%) versus 8 (2.4%) positive samples out of 337 initially analyzed samples. The culture sensitivity considerably improved to 1.7 times lower than that of f-ITS2-PCR-CE after the inoculation volume was increased to 100 µl in the additional 82 samples. Moreover, the molecular technique, unlike routine cultivation, enabled precise pathogen composition determination in polymicrobial samples. In conclusion, the f-ITS2-PCR-CE method was shown to be a quick and efficient tool for culture-independent detection and identification of fungi in urinary tract-related samples, demonstrating a higher sensitivity than culture.

Recent advances in CE and microchip-CE in clinical applications: 2014 to mid-2017

CE and microchip CE (ME) are powerful tools for the analysis of a number of different analytes and have been applied to a variety of clinical fields and human samples. This review will present an overview of the most recent applications of these techniques to different areas of clinical medicine during the period of 2014 to mid-2017. CE and ME have been applied to clinical chemistry, drug detection and monitoring, hematology, infectious diseases, oncology, endocrinology, neonatology, nephrology, and genetic screening. Samples examined range from serum, plasma, and urine to lest utilized materials such as tears, cerebral spinal fluid, sweat, saliva, condensed breath, single cells, and biopsy tissue. Examples of clinical applications will be given along with the various detection systems employed.