Azole resistance poses a problem for the management of patients with invasive aspergillosis. Former species are in fact groups of closely related species (or complexes); cryptic species frequently ...show high antifungal resistance. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) EUCAST Definitive Document (E.Def) 9.3.2 includes guidelines for antifungal susceptibility testing on
spp. and clinical breakpoints for amphotericin B, itraconazole, voriconazole, posaconazole, and isavuconazole against
,
,
,
, and
. New clinical breakpoints were released in February 2020 and one of the most relevant modifications was the definition of the new "susceptible, increased exposure" (formerly "intermediate") category. Another relevant change was the adoption of the concept of area of technical uncertainty (ATU) that refers to problematic areas which involve uncertainty of susceptibility categorisation (e.g., when minimum inhibitory concentrations (MICs) for susceptible and resistant organisms overlap). To accommodate both the new "susceptible, increased exposure" category and the concept of ATU, MICs of azoles and amphotericin B that fall in the former "intermediate" category have been automatically categorized as either R (amphotericin B) or ATU (triazoles). Finally, EUCAST-AFST (Antifungal Susceptibility Testing) decided to adopt new breakpoints for less common species provided that the epidemiological cut-off value (ECOFF) is below or comparable to the breakpoint for the type species (
).
We studied whether short tandem repeats of Aspergillus fumigatus (STRAf) can differentiate between invasive and colonizing genotypes of A. fumigatus. Of the 395 genotypes detected (n = 1,373 ...isolates), 50 were clusters and 24 (6% of all genotypes) involved the patients with invasive aspergillosis and those colonized with A. fumigatus, indicating that genotyping cannot discriminate between invasive and colonizing isolates.
Introduction
This study aimed to examine the relationship among adequate dose, serum concentration and clinical outcome in a non-selected group of hospitalized patients receiving antifungals.
Methods
...Prospective cross-sectional study performed between March 2015 and June 2015. Dosage of antifungals was considered adequate according to the IDSA guidelines, whereas trough serum concentrations (determined with HPLC) were considered adequate as follows: fluconazole > 11 µg/ml, echinocandins > 1 µg/ml, voriconazole 1–5.5 µg/ml and posaconazole > 0.7 µg/ml.
Results
During the study period, 84 patients (65.4% male, 59.6 years) received antifungals for prophylaxis (40.4%), targeted (31.0%) and empirical therapy (28.6%). The most frequent drug was micafungin (28/84; 33.3%) followed by fluconazole (23/84; 27.4%), voriconazole (15/84; 17.9%), anidulafungin (8/84; 9.5%), posaconazole (7/84; 8.3%) and caspofungin (3/84; 3.6%). Considerable interindividual variability was observed for all antifungals with a large proportion of the patients (64.3%) not attaining adequate trough serum concentrations, despite receiving an adequate antifungal dose. Attaining the on-target serum antifungal level was significantly associated with a favorable clinical outcome (OR = 0.02; 95% CI 0.01–0.64;
p
= 0.03), whereas the administration of an adequate antifungal dosage was not.
Conclusions
With the standard antifungal dosage, a considerable proportion of patients have low drug concentrations, which are associated with poor clinical outcome.
Microbiological diagnosis of biofilm-related infections Macià, María D; Del Pozo, José Luis; Díez-Aguilar, María ...
Enfermedades infecciosas y microbiologia clinica,
2018 Jun - Jul, 20180601, Volume:
36, Issue:
6
Journal Article
Peer reviewed
Biofilm-related infections represent a serious health problem, accounting for 65- 80% of all infections. The infections are generally chronic and characterized by the persistence of the ...microorganism, due to the increased resistance of biofilms to both the immune system and antimicrobials. Biofilms can be located to almost every human body tissue and on exogenous devices such as catheters, pacemakers, prosthetic material, implants, urinary catheters, etc. Traditional antimicrobial susceptibility studies in clinical microbiology laboratories have lied on the study of planktonic form of microorganisms. However, this approach might lead to miss the biofilm characteristics and to a treatment failure. Microbiological diagnosis and antimicrobial susceptibility studies of biofilm-related infections are complex and, nowadays, represent a challenge that clinicians and microbiologists have to address as a team in the absence of consensus or standardized protocols.
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.
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.
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.
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.
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Trailing is a well-known phenomenon that is defined as reduced but persistent visible growth of Candida spp. at fluconazole concentrations above the MIC. Trailing is commonly detected using the CLSI ...M27-A3 method, although little is known about its frequency when investigated with EUCAST. We assessed the frequency and scope of fluconazole trailing after using EUCAST EDef 7.2. against a large number of Candida spp. isolates from patients with candidemia. We studied 639 fluconazole-susceptible non-krusei Candida spp. isolates from 570 patients admitted to Gregorio Marañón Hospital. Isolates were tested in vitro for fluconazole susceptibility according to the EUCAST EDef 7.2 procedure; trailing was defined as the presence of any residual growth in wells containing fluconazole concentrations above the MIC. According to the mean percentage of trailing observed, isolates were classified as residual trailers (0.1–5%), slight trailers (6%–10%), moderate trailers (11%–15%), and heavy trailers (>15%). The relationship between trailing and genotyping was assessed. The mean overall percentage of trailing was 6.8%, with C. albicans and C. tropicalis showing the highest percentages (9.75% and 9.29%, respectively; P < .001). C. albicans and C. tropicalis had the highest percentage of heavy trailers (>15%). Trailing was not genotype-specific. Fluconazole trailing was observed frequently when EUCAST was used for antifungal susceptibility testing, particularly in isolates of C. albicans and C. tropicalis. The cut-off proposed enabled us to classify the isolates according to the degree of trailing and can be used as the basis for future studies to evaluate the clinical impact of this phenomenon.
The objectives of this study were to gain further insight on
genotype distribution and percentage of clustered isolates between hospitals and to identify potential clusters involving different ...hospitals and cities. We aim to genotype
spp. isolates causing candidemia in patients admitted to 16 hospitals in Spain, Italy, Denmark, and Brazil. Eight hundred and eighty-four isolates (
= 534;
= 282; and
= 68) were genotyped using species-specific microsatellite markers. CDC3, EF3, HIS3, CAI, CAIII, and CAVI were used for
, Ctrm1, Ctrm10, Ctrm12, Ctrm21, Ctrm24, and Ctrm28 for
, and CP1, CP4a, CP6, and B for
. Genotypes were classified as singletons (genotype only found once) or clusters (same genotype infecting two or more patients). Clusters were defined as intra-hospital (involving patients admitted to a single hospital), intra-ward (involving patients admitted to the same hospital ward) or widespread (involving patients admitted to different hospitals). The percentage of clusters and the proportion of patients involved in clusters among species, genotypic diversity and distribution of genetic diversity were assessed. Seven hundred and twenty-three genotypes were detected, 78 (11%) being clusters, most of which (57.7%;
= 45/78) were intra-hospital clusters including intra-ward ones (42.2%;
= 19/45). The proportion of clusters was not statistically different between species, but the percentage of patients in clusters varied among hospitals. A number of genotypes (7.2%; 52/723) were widespread (found at different hospitals), comprising 66.7% (52/78) of clusters, and involved patients at hospitals in the same city (
= 21) or in different cities (
= 31). Only one
cluster was a widespread genotype found in all four countries. Around 11% of
and
isolates causing candidemia are clusters that may result from patient-to-patient transmission, widespread genotypes commonly found in unrelated patients, or insufficient microsatellite typing genetic discrimination.
We examined the rapid evaluation of susceptibility to echinocandins in
spp. using the Etest performed directly on positive blood cultures and anidulafungin-containing agar plates. We prospectively ...collected 80 positive blood cultures (Bactec-FX system, Becton-Dickinson, Cockeysville, MD, USA) with echinocandin-susceptible
spp. (
= 60) and echinocandin-intermediate
(
= 20) from patients with candidemia. Additionally, blood culture bottles of nonfungemic/bacteremic patients were spiked with 35 echinocandin-resistant
species isolates. A total of 2 to 4 drops of medium from each bottle were stroked directly onto both RPMI 1640 agar plates with micafungin and anidulafungin Etest strips (ET
) and Sabouraud agar plates containing 2 mg/liter of anidulafungin. The isolates were tested according to the EUCAST method and Etest standard (ET
). Essential and categorical agreement between the methods was calculated. The essential agreement and categorical agreement between the EUCAST method and ET
and ET
were both >97.4%. The essential agreement between ET
and the EUCAST method for both echinocandins was >97%. The categorical agreement between the
sequence and ET
was 97.4%. The ET
MICs of anidulafungin and micafungin (≥0.19 mg/liter and ≥0.064 mg/liter, respectively) effectively separated all susceptible
wild-type isolates from the resistant
mutant isolates. The categorical agreement (62.6%) between the EUCAST method and growth on anidulafungin-containing plates was poor, with the best agreement observed for
(94.2%). When performed directly on positive blood cultures from patients with candidemia, the Etest with micafungin and anidulafungin is a reliable procedure for the rapid testing of susceptibility to echinocandins in
species isolates.
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