Antifungal susceptibility of Candida species isolated from patients with candidemia in southern Taiwan, 2007–2012: impact of new antifungal breakpoints

The Clinical and Laboratory Standard Institute (CLSI) revised the clinical breakpoints (CBPs) for the azoles and echinocandins against Candida species in 2012. We aimed to report the epidemiology of candidemia and antifungal susceptibility of Candida species and evaluate the impact of new CBPs on antifungal susceptibility in our region. All blood isolates of Candida species were obtained from 2007 to 2012. The minimum inhibitory concentrations of fluconazole, voriconazole, echinocandins and flucytosine against Candida isolates were determined by Sensititre YeastOne system. Differences in susceptibility rates between the CBPs of previous and revised versions of CLSI were examined. Of 709 Candida isolates, the fluconazole‐susceptible rate was 96.5% in Candida albicans, 85.8% in Candida tropicalis and 92.1% in Candida parapsilosis by the revised CBPs. Compared with the susceptibility results by previous CBPs, the marked reductions in susceptibility of C. albicans, C. tropicalis and C. parapsilosis to fluconazole, that of C. tropicalis and C. parapsilosis to voriconazole, that of C. tropicalis and Candida glabrata to anidulafungin and that of C. tropicalis, C. glabrata and Candida krusei to caspofungin by revised CBPs were found. In conclusion, Candida albicans and C. parapsilosis remain highly susceptible to fluconazole. The non‐susceptible rates of Candida species to azoles and echinocandins increase with interpretation by the revised CBPs.     

Prevalence,virulence factors and antifungal susceptibility of Candida spp. isolated from bloodstream infections in a tertiary care hospital in Brazil

Candida spp. are responsible for 80% of all systemic fungal infections and are associated with high mortality rates. This study characterised 79 bloodstream isolates of C. albicans, C. glabrata, C. orthopsilosis, C. parapsilosis and C. tropicalis from patients in a Brazilian hospital. The susceptibility to amphotericin B, caspofungin, fluconazole and voriconazole was determined; virulence factor production was assessed based on haemolysin, phospholipase and proteinase activities, and the patients’ clinical characteristics were analysed. C. albicans was the predominant species (44%), followed by C. glabrata (19%), C. tropicalis (19%), C. parapsilosis (14%) and C. orthopsilosis (4%). The candidemia incidence was 1.52 per 1000 admissions, and the crude mortality rate was 52%. One C. albicans isolate was resistant to fluconazole and voriconazole. Moreover, 20.2%, 2.5% and 3.8% of the isolates exhibited dose‐dependent susceptibility to fluconazole, voriconazole and caspofungin, respectively. In conclusion, although the C. glabrata incidence was higher than that usually described in Brazil, its increase was previously observed in studies conducted worldwide. Furthermore, the azole resistance of the C. albicans isolate could be due to previous exposure to these antifungals. These results highlight the importance of epidemiological studies and will facilitate an improved understanding of candidemia in the studied hospital.     

The increased role of non‐albicans species in candidaemia: results from a 3‐year surveillance study

Various studies have documented a shift in species distribution in Candida bloodstream infections (BSI), but there are little data from Southeast Asia. This study was performed to determine the species epidemiology and antifungal susceptibilities of Candida species BSI in Singapore. Candida spp. from BSI were collected from a tertiary and secondary referral hospital, and an obstetrics/paediatric hospital over a 3‐year period. The most common isolates were Candida albicans (36%), Candida tropicalis (27%), Candida glabrata (16%) and Candida parapsilosis (16%). Candida parapsilosis and C. albicans were predominant in the paediatric hospital, and C. albicans and C. tropicalis predominant in the other two institutions. Candida tropicalis temporarily replaced C. albicans as the predominant strain from BSI in 2006. Overall, 87.3% of Candida isolates were susceptible to fluconazole, and 10.4% classified as susceptible‐dose‐dependent. Fluconazole resistance was detected in C. tropicalis (3.6%), C. parapsilosis (2.1%) and C. glabrata (4.0%). Candida albicans is the predominant species isolated from BSI in Singapore. However, non‐albicans species accounted for nearly two‐thirds of all cases of candidaemia and the relative increase in C. tropicalis infections deserves further investigation. Resistance to fluconazole was uncommon.     

Prevalence of biofilm formation in clinical isolates of Candida species causing bloodstream infection

Candida species are the fourth most common cause of nosocomial invasive infections. Biofilm formation is recognised as one virulence factor of Candida species. A total of 243 Candida albicans, 81 C. glabrata, 33 C. parapsilosis, 14 C. dubliniensis, 8 C. tropicalis, 8 C. lusitaniae, 5 C. krusei and 1 C. pelliculosa isolates causing bloodstream infections were evaluated for biofilm formation. The biofilm formed on silicone elastomer preincubated with human serum was quantified by estimation of the metabolic activity through XTT assay and visualised by light and scanning electron microscopy. Forty per cent of the C. albicans isolates formed biofilm compared to 88.7% of the non‐albicans Candida isolates (P < 0.0001). Among non‐albicans Candida spp., biofilm formation was most commonly observed in C. tropicalis and C. lusitaniae (100%), followed by C. glabrata (95%), C. dubliniensis (85.7%) and C. parapsilosis (66.7%). A quantitative correlation was observed between the amount of biofilm observed microscopically, and that determined by metabolic activity measurements. The biofilms of all Candida species were composed of basal yeast cells with the exception of C. parapsilosis which produced biofilms consisting of pseudohyphae and aggregated yeast cells. These results suggest that biofilm formation as a virulence factor might have a higher significance for non‐albicans Candida species than for C. albicans.     

Epidemiological investigation of Candida species causing bloodstream infection in paediatric small bowel transplant recipients

Small bowel transplantation (SBT) can be a life‐saving medical procedure. However, these recipients experience high risk of bloodstream infections caused by Candida. This research aims to characterise the SBT recipient gut microbiota over time following transplantation and investigate the epidemiology of candidaemia in seven paediatric patients. Candida species from the recipients' ileum and bloodstream were identified by internal transcribed spacer sequence and distinguished to strain by multilocus sequence typing and randomly amplified polymorphic DNA. Antifungal susceptibility of bloodstream isolates was determined against nine antifungals. Twenty‐two ileostomy samples harboured at least one Candida species. Fungaemia were caused by Candida parapsilosis, Candida albicans, Candida glabrata, Candida orthopsilosis and Candida pelliculosa. All but three bloodstream isolates showed susceptibility to all the antifungals tested. One C. glabrata isolate showed multidrug resistance to itraconazole, amphotericin B and posaconazole and intermediate resistance to caspofungin. Results are congruent with both endogenous (C. albicans, C. glabrata) and exogenous (C. parapsilosis) infections; results also suggest two patients were infected by the same strain of C. parapsilosis. Continuing to work towards a better understanding of sources of infection—particularly the exogenous sources—would lead to targeted prevention strategies.     

Rapid identification of yeast by fluorescence in situ hybridisation from broth and blood cultures

Candida species including species other than Candida albicans are of importance as causative agents of sepsis in intensive‐care units, requiring prompt initiation of targeted therapy. While fluconazole is usually active against Candida albicans, non‐Candida albicans species often require more sophisticated approaches. A rapid species diagnosis is therefore desirable and can be provided by fluorescence in situ hybridisation (FISH). However, broad evaluation studies of described probes are largely lacking and the probe panel that has been described is incomplete. As an addition to previously described C. albicans FISH probes, we evaluated published DNA probes for C. glabrata and C. krusei, as well as newly designed DNA probes for C. krusei, C. lusitaniae, C. parapsilosis, C. tropicalis, Crypotococcus neoformans and a group of intrinsically fluconazole‐resistant Candida species for FISH with 22 reference strains, 23 well‐characterised laboratory control strains, 169 isolates from clinical samples and 48 blood cultures. Sensitivity and specificity of >99% were demonstrated for all evaluated species‐specific probes, whereas the probe that binds to a heterogeneous group of intrinsically fluconazole‐resistant Candida species correctly identified eight of nine fluconazole‐resistant clinical isolates. FISH yielded reliable results using the classical FISH procedure as well as a recently described slide chamber‐based method. Given this good sensitivity and specificity, FISH may be applied for rapid identification of yeast in screening analyses, thus giving the opportunity for more precise targeting of antimycotic therapy.     

Species distribution and antifungal susceptibility of blood Candida isolates at a tertiary hospital in southern Taiwan, 1999–2006

The aim of this study was to evaluate the incidence of candidaemia, consumption of fluconazole and susceptibility of blood Candida isolates at a tertiary hospital. From January 1999 to September 2006, all candidaemic episodes were identified and available strains were evaluated for the susceptibilities of antifungal agents. Annual defined daily doses of antifungal agents were collected. There had been 909 Candida isolates detected from the bloodstream of 843 patients during the study period. Among them, 740 isolates were available for the susceptibilities of antifungal agents. The incidence density of candidaemia was 28 episodes per 10 000 patient‐days. Species distribution of 909 isolates did not vary annually, but varied greatly in the units of the hospital. Candida parapsilosis was the more prominent (30.1%) isolate in the paediatric units, where C. tropicalis and C. glabrata were less common (12.3% and 1.4% respectively). Resistance rates for itraconazole, fluconazole and voriconazole were 6.9%, 3.8% and 3.8% respectively. There were 25 (3.4%) isolates resistant to amphotericin‐B. Although fluconazole usage increased over time (r² = 0.45; P = 0.07), fluconazole resistance did not increase accordingly (P = 0.33). In our institution in which the incidence of candidaemia was high, fluconazole resistance among blood Candida isolates remained rare.     

Epidemiology and molecular mechanisms of antifungal resistance in Candida and Aspergillus

The significant increase in the use of antifungal agents, both for the treatment of candidiasis and invasive aspergillosis and as azole fungicides in agricultural crop protection has resulted in the emergence of resistant clinical isolates, particularly to triazoles and echinocandins. Notably, among isolates that were primarily sensitive to fluconazole such as Candida parapsilosis and Candida tropicalis have witnessed an emerging resistance development. Also for echinocandins, the occurrence of Candida isolates with lower susceptibility to these drugs has been reported, which is possibly due to its broad clinical use. Triazole resistance among Aspergillus fumigatus and other Aspergillus species is commonly found in European and Asian countries. Specific mutations are associated with azole resistance in A. fumigatus and these mutations are now reported globally from six continents. Therefore, we highlight the need to conduct antifungal resistance surveillance studies using clinical isolates of Candida and Aspergillus in different geographical regions and monitoring of the infection rates in distinct population groups for early detection of resistance to these drugs and implementation of efficient policies for infection control and treatment.     

Regional data analysis of Candida non‐albicans strains collected in United States medical sites over a 6‐year period, 2006–2011

Limited data are available on temporal and geographic variation of occurrence and antifungal resistance of non‐C. albicans Candida species (non‐CA‐CSP) from the USA. The objective of this study was to evaluate the occurrence and antifungal resistance of 1694 isolates of non‐CA‐CSP collected during the period 2006–2011. Isolates were recovered in 33 hospitals located in four regions: Northcentral, North‐east, South‐east and West and tested using CLSI reference broth microdilution methods. Non‐CA‐CSP represented 55.6% of all Candida. C. glabrata was most predominant (39–42% of non‐CA‐CSP). Infections due to C. glabrata, C. krusei and C. dubliniensis increased over the 6 years. Anidulafungin (3.6%) and caspofungin (5.7%) resistance were prominent among C. glabrata from the North‐east and West regions respectively. Resistance to micafungin was detected in 2.0% and 2.9% of C. glabrata from the West and North‐east regions respectively. Echinocandin resistance was low, except for C. dubliniensis. Azole resistance was most prominent among C. glabrata from the South‐east (13.6% fluconazole R) and the West (18.0%). Cross‐resistance among three tested azoles was observed in C. glabrata from all regions. Whereas differences in species distribution and antifungal R varied across geographic regions, there was little evidence of temporal increase in resistance to azoles or echinocandins in the monitored non‐CA‐CSP.     

Resveratrol and its antifungal activity against Candida species

Resveratrol is a natural stilbene synthesised by plants. This compound has been shown to inhibit the growth of Candida albicans TIMM 1768 efficiently. Till date, no information is available for other Candida species. The evaluation of the antimicrobial activity of resveratrol was analysed by the inhibition of the growth and metabolism assays. Our data indicate that resveratrol is not effective against Candida albicans and non‐C. albicans species (C. dubliniensis, C. glabrata, C. tropicalis, C. parapsilosis and C. krusei) in vitro. The potential candidacidal activity could not be confirmed.     

Vulvovaginal candidiasis: species distribution,fluconazole resistance and drug efflux pump gene overexpression

The increasing incidence of vulvovaginal candidiasis (VVC) and the emergence of fluconazole resistance are an indisputable fact. However, little information is available regarding the correlation between fluconazole resistance in vaginal Candida albicans and the expression of drug efflux pump genes. In this study, we investigated the species distribution, fluconazole susceptibility profiles and the mechanisms of fluconazole resistance in Candida strains. In total, 785 clinical Candida isolates were collected from patients with VVC. C. albicans was the most frequently isolated species (n = 529) followed by C. glabrata (n = 164) and C. krusei (n = 57). Of all Candida isolates, 4.7% were resistant to fluconazole. We randomly selected 18 fluconazole‐resistant isolates of C. albicans to evaluate the expression of CDR1, CDR2, MDR1 and FLU1 genes. Compared with fluconazole‐susceptible C. albicans isolates, CDR1 gene expression displayed 3.16‐fold relative increase, which was statistically significant. CDR2, MDR1 and FLU1 overexpression was observed in several fluconazole‐resistant C. albicans isolates, but statistical significance was not achieved. These results demonstrate a high frequency of non‐albicans species (32.6%); however, C. albicans is the most common Candida species implicated in vaginitis, and this strain displays considerable fluconazole resistance. Meanwhile, our study further indicates that fluconazole resistance in C. albicans may correlate with CDR1 gene overexpression.     

Incidence,species distribution and antifungal sensitivity pattern of vaginal yeasts in Sri Lankan women

A total of 432 high vaginal swabs from patients with vulvovaginitis were processed for the presence of yeasts. Candida species were isolated from 40 (32.4%). In comparison, vaginal swabs from 107 normal asymptomatic women yielded only eight (7.3%) isolates (P<0.001). Candida albicans was the commonest species isolated (76%). Other species included C. tropicalis, C. krusei, C. kefrr, C. glabrata and C. guilliermondii. Of the C. albicans isolates, 42.8% showed in vitro resistance to miconazole and 6.6% to econazole. Ninety-two percent of the isolates were sensitive to the polyenes (nystatin and amphotericin B) and 87% and 74% to clotrimazole and ketaconazole respectively. Zusammenfassung. Insgesamt 432 Abstriche aus dem oberen Vaginalbereich von Vulvovaginitis-Patientinnen wurden auf Hefen untersucht. Aus 40 Proben (32.4%) wurden Candida-Arten isoliert. Bei einer Vergleichsgruppe von 107 asymptomatischen Frauen wurden nur bei acht (7.3%) Hefen isoliert (p<0.001). Candida albicans wurde am häufigsten isoliert (76%). Andere Isolate umfaßten C. tropicalis, C. krusei, C. kefyr, C. glabrata und C. guilliermondii. Von den Isolaten waren 42.8% in vitro resistent gegen Miconazol und 6.6% gegen Econazol. Für die Polyene waren 92% empfindlich und 87% fur Clotrimazol und 74% für Ketoconazol.     

The prevalence of Candida onychomycosis in Southeastern Serbia from 2011 to 2015

Despite the increasing of onychomycosis caused by Candida spp., in referent literature, there is still data insufficiency about this nail infection. The objectives of this retrospective study were to determine epidemiological characteristics of Candida onychomycosis, the antifungal susceptibility of isolated species in vitro, and to compare the results of antifungal susceptibility testing with conducted treatment in period from 2011 to the end of March 2015. Out of 761 patients who were underwent clinical and mycological examinations, 137 had Candida species isolated from nails. The dominant species was Candida albicans (C. albicans) (36.59%) followed by C. parapsilosis (23.78%), C. krusei (9.76%), and C. guilliermondii (6.71%). Antifungal susceptibility in vitro testing showed good susceptibility to antimycotics, except C. krusei, which was resistance to fluconazole (FCZ) and isolates of C. tropicalis and C. glabrata which were dose dependent to itraconazole (ITZ) and fluconazole. Evaluation of medical histories determined that combined therapy, which included pulsed systemic regimen of ITZ with topical application of clotrimazole, had better clinical outcomes regarding the proscribed only topical application of clotrimazole. Multidisciplinary approach of dermatologists and mycologists is required in solving the problem of onychomycosis, which is the dominant nail disease.     

Repeated exposure of Candida spp. to miconazole demonstrates no development of resistance

Oropharyngeal candidiasis (OPC) is a common infection among the immuno‐compromised population. Treatments include both systemic azoles, most commonly fluconazole (FLU), and topical agents such as miconazole (MICON). However, resistance to FLU has been reported with a greater frequency. The aim of this study was to determine the potential for development of resistance following repeated exposure of Candida spp. to MICON. Two clinical isolates each of Candida albicans, C. glabrata, and C. tropicalis were tested. Fifteen passages of each strain were performed in concentrations of MICON at 0.5 minimum inhibitory concentration (MIC), 1 MIC, 2 MIC and 4 MIC, with MIC determinations performed on growth obtained following each passage. There was no increase in the MIC of four of the six strains following fifteen passages in MICON. One C. albicans strain demonstrated a four‐five dilution increase in MICON MIC at all concentrations and one C. glabrata strain showed a fivefold MICON MIC increase when exposed to 4 MIC. Although an increase in MIC was noted in these two isolates, the MICON MIC was still very low (0.5 μg ml^?1). In general, there was no increase in MIC demonstrated by repeated exposure to MICON in this study.     

Epidemiology and antifungal susceptibility patterns of candidemia from a tertiary centre in Western Australia

Candidemia is a common invasive fungal infection with a high mortality rate. We performed a retrospective audit of candidemia at a tertiary centre in Western Australia, 2005–2014. There were 167 episodes of candidemia due to 173 isolates of Candida. Candida albicans (40.5%), Candida glabrata complex (30.6%), Candida parapsilosis complex (14.4%) were the most common species causing candidemia across the study. Of the tested isolates, 17.7% (11/62) were non-susceptible to fluconazole and 13.6% (9/66) non-susceptible to caspofungin. 22.8% (8/35) C. glabrata complex were fluconazole resistant and 17.1% (6/35) were non-susceptible to caspofungin. Candida glabrata complex was more common in the latter time period, but there were no susceptibility changes over time. In our setting, the prevalence of C. glabrata complex and antifungal non-susceptibility is high, and the prevalence of C. glabrata complex is increasing.     

Mating genotypes and susceptibility profiles of clinical isolates of Candida glabrata from Turkey

The sexual cycle of Candida glabrata is not known; however, genomic evidence is indicative of recombination among subpopulations and the genome harbours genes necessary for undergoing mating and meiosis, which may increase fitness. The relationship between specific mating type‐like (MTL) loci and antifungal susceptibility is not well understood in C. glabrata. We investigated different combinations of clinical C. glabrata isolate mating types and their antifungal susceptibility profiles. Allele profiles of the mating genes of 103 clinical C. glabrata isolates were identified, and their antifungal susceptibility to azoles, echinocandins and amphotericin B were compared. The majority (88.3%) of screened isolates harboured the a allele in the locus. The MTL1, MTL2 and MTL3 loci harboured a (88.3%), a (95.1%), and α (71.8%) alleles, respectively. The C. glabrata isolates were susceptible to echinocandins but displayed high minimal inhibitory concentrations (MICs) for azoles. The MIC ranges and MIC90 values of all isolates were 1.0 to ≥64 and 8.0 μg mL^?1 for fluconazole, 0.06 to ≥16.0 and 0.5 μg mL^?1 for voriconazole, 0.06 to ≥16.0 and 1.0 μg mL^?1 for posaconazole, ≤0.015 to 0.06, and 0.03 μg mL^?1 for caspofungin, ≤0.015 to 0.06 and 0.015 μg mL^?1 for anidulafungin and 0.5‐2 and 2.0 μg mL^?1 for amphotericin B, respectively. The mating gene alleles of the clinical C. glabrata isolates were not associated with differences in the MICs of the tested antifungals, except for the MTL3 α‐allele and echinocandins. The mating genotypes of the clinical C. glabrata isolates had no recognisable common effect on antifungal susceptibility.     

Comparison of fks gene mutations and minimum inhibitory concentrations for the detection of Candida glabrata resistance to micafungin: A systematic review and meta‐analysis

Candida resistance to antifungals impaired invasive candidiasis outcome. In a context of echinocandin resistance development, we aimed to evaluate the association between phenotypic resistance to micafungin and fks mutations of Candida glabrata. For this systematic review and meta‐analysis, we searched MEDLINE, Scopus and Web of Science for reports published up to December 2017. Studies of C glabrata candidiasis with minimum inhibitory concentrations (MIC) determination of micafungin and fks genotyping were included. Reviews, studies not using reference methods, non‐glabrata Candida, experimental isolates and undetailed mutations were excluded. Two authors independently assessed the eligibility of articles and extracted data. The main outcome was the diagnostic accuracy of fks mutations compared to micafungin MIC for C glabrata, measured as fixed‐effect odd ratio. Heterogeneity was calculated with the I² statistic. This study is registered with PROSPERO (CRD42018082023). Twenty‐four studies were included in the meta‐analysis. Pooled analysis found that S663P (OR 7.25, 95% CI 3.50‐15.00; P < 0.00001), S629P (OR 3.70, 1.64‐8.33; P = 0.002) and F659del (OR 5.66, 1.22‐26.18; P = 0.03) were associated with increased risk of having a resistant isolate according to authors' interpretation of MICs. In sensitivity analysis based on new CLSI clinical breakpoints, the ORs for S663P and S629P remained significant. Genotyping of isolates of C glabrata for S663P and S629P mutations is an effective alternative to micafungin susceptibility tests. Relevant molecular markers of drug resistance will significantly improve the management of C glabrata infections.     

Candidaemia in a Polish tertiary paediatric hospital, 2000 to 2010

Data on the epidemiology of invasive Candida infections in paediatric patients in Europe are still limited. The aim of this retrospective study was to analyse the epidemiology of candidaemia in a tertiary paediatric hospital in Poland from 2000 to 2010. Using microbiological records, a total of 118 episodes of candidaemia were identified in 114 children, with an annual incidence of 0.35 episodes/1000 discharges. The highest incidences were found in the medical intensive care unit (5.28), and in neonatal intensive care (1.47). The mortality rate was 8.5%. Candida albicans and C. parapsilosis were the most prevalent species (39.8% and 35.6% respectively). The prevalence of non‐albicans species increased from 12.5% in 2000 to 70% in 2010. No differences were found between C. albicans and C. non‐albicans episodes in terms of demographics, risk factors or mortality. The highest resistance rates (overall 7.6%) were observed for fluconazole (4.3% in C. albicans, 7.1% in C. parapsilosis and 13.8% in other Candida species). Resistance to amphotericin B (2.5%) was limited to non‐albicans isolates. The dynamic changes in species distribution and increasing resistance of fungal pathogens confirm the importance of epidemiological surveillance.     

Phospholipase and proteinase activities of Candida isolates from denture wearers

The aim of the present study was to characterise phospholipase and proteinase activities of oral Candida isolates from 100 denture wearers and to study the relationship of these activities with denture stomatitis. Of 100 patients studied, 44 suffered from denture stomatitis. Specimens were collected by swabbing the denture and underlying mucosa. Isolates were previously identified by conventional mycological and genotypic methods. The phospholipase and proteinase activities were evaluated by agar plate methods. A total of 152 isolates were recovered from denture and underlying mucosa, including 101 Candida albicans, 18 Candida tropicalis, 14 Candida glabrata, 11 Candida guilliermondii, four Candida parapsilosis, two Saccharomyces cerevisiae and one isolate each of Candida dubliniensis and Candida krusei. Most C. albicans (97%) showed phospholipase activity; furthermore, the unique C. dubliniensis isolate showed a moderate phospholipase activity. The isolation of C. albicans (chi‐square test, P = 0.0016) and phospholipase production by Candida spp. (chi‐square test, P = 0.0213) was found to be significantly associated with denture stomatitis. Proteinase production was observed in <30% of isolates, and it was not related to the presence of denture stomatitis (P = 0.7675). Candida albicans isolates may produce both virulence factors, although the proteinase production was only observed in <30% of the isolates. Phospholipase production was exclusive of C. albicans and C. dubliniensis.