Clonal population of flucytosine-resistant Candida tropicalis from blood cultures, Paris, France.
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ABSTRACT:
SUBMITTER: Desnos-Ollivier M
PROVIDER: S-EPMC2570934 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Candida dubliniensis and Candida albicans are two closely related species. Although C. dubliniensis is less pathogenic, it has a higher propensity to develop resistance to fluconazole and some strains exhibit intrinsic resistance to 5-flucytosine (5-FC). All 5-FC-resistant isolates from Kuwait were previously shown to belong to one of seven internal transcribed spacer (ITS) region of rDNA-based haplotypes. This study performed fingerprinting of C. dubliniensis isolates by multilocus sequence typing (MLST) to determine population structure of 5-FC-resistant and -susceptible strains and compared the results with data from a global collection of isolates. Fifty-two C. dubliniensis isolates previously analyzed and 58 additional isolates mostly collected during 2010-2013 and characterized by phenotypic and molecular methods were used. ITS-based haplotypes were identified by haplotype-specific PCR and/or by PCR-DNA sequencing of rDNA. Population structure was determined by 8-loci-based MLST. E-test was used to determine susceptibility to 5-FC, fluconazole, voriconazole and amphotericin B. Five ITS haplotypes (ITSH) were detected among 110 C. dubliniensis isolates. The ITSH1 was most common (n = 80 isolates) followed by ITSH4 (n = 25 isolates). Two isolates each belonged to ITSH5 and ITSH8 while one isolate belonged to ITSH7. MLST identified 16 diploid sequence types (DSTs) including six new DSTs. DST11 (n = 52) and DST14 (n = 25) were dominant genotypes and were confined (together with DST21) to Middle-Eastern countries. Other DSTs (excluding some new DSTs) had a wider global distribution as they were identified from various other countries. Only ITSH4 isolates (n = 25) belonged to DST14, were resistant to 5-FC and contained S29L mutation in CdFCA1. ITSH5, ITSH7 and ITSH8 isolates belonged to different DSTs. Thus, clinical C. dubliniensis isolates in Kuwait exhibited limited genotypic heterogeneity and most isolates belonged to region-specific DSTs. All 5-FC-resistant C. dubliniensis isolates belonged to ITSH4 and MLST-based DST14 genotype. Placement of some isolates into additional ITS haplotypes is also supported by MLST data.
| S-EPMC5381908 | biostudies-literature
Project description:Some members of the genus Candida are among the most common human fungal pathogens and cause serious diseases especially in immunocompromised people. A yeast was isolated from a blood culture from an immunocompromised cancer patient who suffered from acute pneumonia. The growth characteristics of the yeast on CHROMagar Candida were similar to those of Candida tropicalis, whereas the API ID 32C system identified the yeast as Candida silvicola. On the basis of the nucleotide divergence in the D1/D2 domain of the 26S nuclear rRNA (nrRNA) gene, as well as the internal transcribed spacer (ITS) domain of the nrRNA gene region, a new species, Candida pseudoaaseri sp. nov. with type strain VK065094 (CBS 11170(T)), which was found to be closely related to Candida aaseri, is proposed. While C. aaseri strains were susceptible to all tested antifungals, the new species is resistant to flucytosine and may also be distinguished from C. aaseri by its ability to assimilate l-rhamnose, whereas its colony morphology on CHROMagar Candida may be helpful for differentiation.
| S-EPMC3233011 | biostudies-literature
Project description:Bed bugs are hematophagous insects responsible for a re-emerging and challenging indoor pest in many countries. Bed bugs infestations may have health consequences including nuisance biting, cutaneous and systemic reactions. This resurgence can probably be attributed to factors such as increased international travel and development of resistance against insecticides. Resistance against pyrethroids has been reported several times from the USA and rarely in Europe. In France, very few data on bed bugs are available. The present study aimed to assess the infestation by bed bugs of a complex of two high-rise apartment buildings in the suburb of Paris and to evaluate their susceptibility to pyrethroid insecticides. We inspected for bed bugs 192 out of 198 apartments units (97%) and interviewed their residents. 76 (39.6%) apartments were infested. Among the 97 residents living in infested apartments, 53 (54.6%) reported bed bug bites. A total of 564 bed bugs were collected in the infested units. Bioassays showed that 54 out of 143 bed bugs were resistant to pyrethroids (37.8%; 95% confidence interval: 29.9-45.7%). DNA sequencing showed that all bed bugs tested (n=124) had homozygous L925I kdr-like gene mutation. The level of pyrethroid resistance found indicates that this phenomenon was already established in the site and prompts the need to reevaluate the wide use of pyrethroids to control bed bugs.
| S-EPMC3671460 | biostudies-literature
Project description:Infections caused by the coexistence of Candida glabrata echinocandin-resistant and echinocandin-susceptible cells may be possible, and the detection of FKS mutants when the proportions of FKS mutants are underrepresented poses a problem. We assessed the role of EUCAST and methods directly performed on positive blood cultures-Etest (ETDIR) and anidulafungin-containing agar plate assays-for detecting resistance in C. glabrata isolates containing different amounts of echinocandin-susceptible and -resistant Candida glabrata isolates. We studied 10 pairs of C. glabrata isolates involving parental echinocandin-susceptible isolates and isogenic echinocandin-resistant FKS mutant isolates. Three inocula per pair (1 × 103 to 5 × 103, 1 × 102 to 5 × 102, and 10 to 50 CFU/ml) spanning suspensions with different amounts of susceptible/resistant isolates (9/1, 5/5, and 1/9 proportions for each the three inocula) were prepared. The suspensions were spiked in Bactec bottles and incubated until they were positive, and the three methods were compared. The EUCAST method showed echinocandin resistance when the bottles were spiked with susceptible/resistant isolates at 5/5 and 1/9 proportions; the results for the suspensions with a 9/1 proportion of susceptible/resistant isolates were susceptible for three pairs. We observed with the ETDIR resistance to both echinocandins in all pairs (resistance to micafungin and anidulafungin; MICs, ≥0.064 mg/liter and ≥0.125 mg/liter, respectively) and a double ring of growth inhibition in two pairs. The anidulafungin-containing plates showed fungal growth in the 90 spiked blood cultures at 48 h. Testing of echinocandin susceptibility with the ETDIR directly on the positive blood culture bottles is a reliable and rapid method to detect echinocandin resistance in C. glabrata On the other hand, resistance can be missed with the EUCAST method when resistant isolates are underrepresented.
| S-EPMC6395934 | biostudies-literature
Project description:Homo sapiens fresh whole blood was infected with Candida tropicalis. RNA-pool of both species extracted at 0min (control), 15, 30, 60, 120, 240 min. Samples are rRNA depleted. Measurement of Candida tropicalis gene expression.
2019-07-31 | GSE114178 | GEO
Project description:DNA fingerprinting of Candida dubliniensis isolates using the species-specific probe Cd25 previously showed that this species consists of two distinct groups, termed Cd25 group I and Cd25 group II. The present study investigated the population structure of 30 C. dubliniensis oral isolates from Saudi Arabia and Egypt using Cd25 fingerprinting and rRNA gene internal transcribed spacer region-based genotyping. Cd25 fingerprinting analysis of these isolates revealed two distinct populations, the first of which consisted of 10 closely related genotype 1 isolates (average similarity coefficient [S(AB)] value, 0.86). The second population of 20 isolates was much more heterogeneous (average S(AB) value, 0.35) and consisted of two distinct subpopulations, one of which consisted of genotype 3 isolates (n = 13) and the other of genotype 4 isolates (n = 7). A mixed dendrogram generated from the fingerprint data from the 30 Saudi Arabian and Egyptian isolates, 5 Israeli isolates, and 51 previously characterized international isolates (32 of Cd25 group I and 19 of Cd25 group II) revealed the presence of three distinct main clades. The first corresponded to the previously described Cd25 group I and contained all the Saudi Arabian, Egyptian, and Israeli genotype 1 isolates mixed with international isolates. The second clade corresponded to the previously described Cd25 group II and contained three Israeli isolates, one genotype 2 isolate, one genotype 3 isolate, and a genotype 4 variant isolate, which were mixed with international isolates. The third clade has not been described before and consisted solely of the 20 Saudi Arabian and Egyptian genotype 3 and 4 isolates identified in this study and a previously described genotype 4 Israeli isolate. All 20 Cd25 group III isolates exhibited high-level resistance to 5-flucytosine (MIC > or = 128 microg/ml), whereas all Cd25 group I and Cd25 group II isolates tested (10 Saudi Arabian and Egyptian, 16 Israeli, and 24 international) were susceptible to 5-flucytosine (MIC < or = 0.125 microg/ml). The results of this study show for the first time the presence of a novel 5-flucytosine-resistant clade of C. dubliniensis (Cd25 group III) that is predominant among isolates from Saudi Arabia and Egypt and absent from a previously characterized international collection of 98 isolates from 15 countries.
| S-EPMC1233943 | biostudies-literature
Project description:Candida tropicalis is one of the major candidaemia agents, associated with the highest mortality rates among Candida species, and developing resistance to azoles. Little is known about the molecular mechanisms of azole resistance, genotypic diversity, and the clinical background of C. tropicalis infections. Consequently, this study was designed to address those questions. Sixty-four C. tropicalis bloodstream isolates from 62 patients from three cities in Iran (2014-2019) were analyzed. Strain identification, antifungal susceptibility testing, and genotypic diversity analysis were performed by MALDI-TOF MS, CLSI-M27 A3/S4 protocol, and amplified fragment length polymorphism (AFLP) fingerprinting, respectively. Genes related to drug resistance (ERG11, MRR1, TAC1, UPC2, and FKS1 hotspot9s) were sequenced. The overall mortality rate was 59.6% (37/62). Strains were resistant to micafungin [minimum inhibitory concentration (MIC) ≥1 μg/ml, 2/64], itraconazole (MIC > 0.5 μg/ml, 2/64), fluconazole (FLZ; MIC ≥ 8 μg/ml, 4/64), and voriconazole (MIC ≥ 1 μg/ml, 7/64). Pan-azole and FLZ + VRZ resistance were observed in one and two isolates, respectively, while none of the patients were exposed to azoles. MRR1 (T255P, 647S), TAC1 (N164I, R47Q), and UPC2 (T241A, Q340H, T381S) mutations were exclusively identified in FLZ-resistant isolates. AFLP fingerprinting revealed five major and seven minor genotypes; genotype G4 was predominant in all centers. The increasing number of FLZ-R C. tropicalis blood isolates and acquiring FLZ-R in FLZ-naive patients limit the efficiency of FLZ, especially in developing countries. The high mortality rate warrants reaching a consensus regarding the nosocomial mode of C. tropicalis transmission.
| S-EPMC7398758 | biostudies-literature
Project description:BACKGROUND: Candida glabrata has emerged as an important human pathogen associated with systemic and mucosal infections. Here, we describe isolation of two cholesterol-dependent Candida glabrata strains from a candidemia patient which failed to grow on the media devoid of a cholesterol source. METHODS: Both the isolates were recovered from BACTEC Plus Aerobic/F blood culture bottles of a candidemic patient. Since these isolates failed to grow on Sabouraud dextrose agar, Mueller-Hinton agar and RPMI 1640 agar media, their definitive identification required PCR sequencing of the internally transcribed spacer (ITS)1 and ITS2 regions of rDNA and the D1/D2 region sequences within 26S rRNA gene. The cholesterol auxotrophy was determined by their ability to grow on media containing a cholesterol source. The minimum inhibitory concentrations (MICs) to antifungal agents were determined by Etest. RESULTS: The identity of the isolates was confirmed by sequencing of the ITS1 and ITS2 regions of rDNA and the D1/D2 region sequences within 26S rRNA gene and also by matrix-assisted laser desorption and ionization-time-of-flight mass spectrometry with 99.9% confidence value. Both the isolates showed good growth only when media were supplemented with cholesterol, oxbile or blood. Additionally, these isolates were resistant to amphotericin B (MIC ?32 ?g/ml), fluconazole (MIC ?256 ?g/ml), voriconazole (MIC ?32 ?g/ml), itraconazole (MIC ?32 ?g/ml), and posaconazole (MIC ?32 ?g/ml), but susceptible to caspofungin (MIC range 0.064 to 0.19 ?g/ml). CONCLUSION: This appears to be the first report on isolation of cholesterol-dependent strains of C. glabrata from a candidemia patient exhibiting resistance to azoles and amphotericin B. Further, the report demonstrates that induction of cholesterol/sterol auxotrophy is associated with resistance to antifungal drugs targeting ergosterol biosynthesis. These observations may have therapeutic implications for the treatment of infections caused by such C. glabrata strains.
| S-EPMC4234190 | biostudies-literature
Project description:Primary resistance in Candida albicans to flucytosine (5-FC) was investigated in 25 strains by identifying and sequencing the genes FCA1, FUR1, FCY21, and FCY22, which code for cytosine deaminase, uracil phosphoribosyltransferase (UPRT), and two purine-cytosine permeases, respectively. These proteins are involved in pyrimidine salvage and 5-FC metabolism. An association between a polymorphic nucleotide and resistance to 5-FC was found within FUR1 where the substitution of cytidylate for thymidylate at nucleotide position 301 results in the replacement of arginine with cysteine at amino acid position 101 in UPRT. Isolates that are homozygous for this mutation display increased levels of resistance to 5-FC, whereas heterozygous isolates have reduced susceptibility. Three-dimensional protein modeling of UPRT suggests that the Arg101Cys mutation disturbs the quaternary structure of the enzyme, which is postulated to compromise optimal enzyme activity. A single resistant isolate, lacking the above polymorphism in FUR1, has a homozygous polymorphism in FCA1 that results in a glycine-to-aspartate substitution at position 28 in cytosine deaminase.
| S-EPMC525410 | biostudies-literature
Project description:Candida tropicalis is a human pathogen that primarily infects the immunocompromised. Whereas the genome of one isolate, C. tropicalis MYA-3404, was originally sequenced in 2009, there have been no large-scale, multi-isolate studies of the genetic and phenotypic diversity of this species. Here, we used whole genome sequencing and phenotyping to characterize 77 isolates of C. tropicalis from clinical and environmental sources from a variety of locations. We show that most C. tropicalis isolates are diploids with approximately 2-6 heterozygous variants per kilobase. The genomes are relatively stable, with few aneuploidies. However, we identified one highly homozygous isolate and six isolates of C. tropicalis with much higher heterozygosity levels ranging from 36-49 heterozygous variants per kilobase. Our analyses show that the heterozygous isolates represent two different hybrid lineages, where the hybrids share one parent (A) with most other C. tropicalis isolates, but the second parent (B or C) differs by at least 4% at the genome level. Four of the sequenced isolates descend from an AB hybridization, and two from an AC hybridization. The hybrids are MTLa/α heterozygotes. Hybridization, or mating, between different parents is therefore common in the evolutionary history of C. tropicalis. The new hybrids were predominantly found in environmental niches, including from soil. Hybridization is therefore unlikely to be associated with virulence. In addition, we used genotype-phenotype correlation and CRISPR-Cas9 editing to identify a genome variant that results in the inability of one isolate to utilize certain branched-chain amino acids as a sole nitrogen source.
| S-EPMC8041210 | biostudies-literature