Defining Optimal Doses of Liposomal Amphotericin B Against Candida auris: Data From an In Vitro Pharmacokinetic/Pharmacodynamic Model.

BACKGROUND: Candida auris isolates exhibit elevated amphotericin B (AMB) minimum inhibitory concentrations (MICs). As liposomal AMB (L-AMB) can be safely administered at high doses, we explored L-AMB pharmacodynamics against C. auris isolates in an in vitro pharmacokinetic/pharmacodynamic (PK/PD) dilution model. METHODS: Four C. auris isolates with Clinical and Laboratory Standards Institute (CLSI) AMB MICs = 0.5-2 mg/L were tested in an in vitro PK/PD model simulating L-AMB pharmacokinetics. The in vitro model was validated using a Candida albicans isolate tested in animals. The peak concentration (Cmax)/MIC versus log10 colony-forming units (CFU)/mL reduction from the initial inoculum was analyzed with the sigmoidal model with variable slope (Emax model). Monte Carlo analysis was performed for the standard (3 mg/kg) and higher (5 mg/kg) L-AMB doses. RESULTS: The in vitro PK/PD relationship Cmax/MIC versus log10 CFU/mL reduction followed a sigmoidal pattern (R2 = 0.91 for C. albicans, R2 = 0.86 for C. auris). The Cmax/MIC associated with stasis was 2.1 for C. albicans and 9 for C. auris. The probability of target attainment was >95% with 3 mg/kg for wild-type C. albicans isolates with MIC ≤2 mg/L and C. auris isolates with MIC ≤1 mg/L whereas 5 mg/kg L-AMB is needed for C. auris isolates with MIC 2 mg/L. CONCLUSIONS: L-AMB was 4-fold less active against C. auris than C. albicans. Candida auris isolates with CLSI MIC 2 mg/L would require a higher L-AMB dose.

Comparative pharmacodynamics and dose optimization of liposomal amphotericin B against Candida species in an in vitro pharmacokinetic/pharmacodynamic model.

As comparative pharmacokinetic/pharmacodynamic (PK/PD) studies of liposomal amphotericin B (L-AMB) against Candida spp. are lacking, we explored L-AMB pharmacodynamics against different Candida species in an in vitro PK/PD dilution model. Eight Candida glabrata, Candida parapsilosis, and Candida krusei isolates (EUCAST/CLSI AMB MIC 0.125-1 mg/L) were studied in the in vitro PK/PD model simulating L-AMB Cmax = 0.25-64 mg/L and t1/2 = 9 h. The model was validated with one susceptible and one resistant Candida albicans isolate. The Cmax/MIC-log10CFU/mL reduction from the initial inoculum was analyzed with the Emax model, and Monte Carlo analysis was performed for the standard (3 mg/kg with Cmax = 21.87 ± 12.47 mg/L) and higher (5 mg/kg with Cmax = 83 ± 35.2 mg/L) L-AMB dose. A ≥1.5 log10CFU/mL reduction was found at L-AMB Cmax = 8 mg/L against C. albicans, C. parapsilosis, and C. krusei isolates (MIC 0.25-0.5 mg/L) whereas L-AMB Cmax ≥ 32 mg/L was required for C. glabrata isolates. The in vitro PK/PD relationship followed a sigmoidal pattern (R2 ≥ 0.85) with a mean Cmax/MIC required for stasis of 2.1 for C. albicans (close to the in vivo stasis), 24/17 (EUCAST/CLSI) for C. glabrata, 8 for C. parapsilosis, and 10 for C. krusei. The probability of target attainment was ≥99% for C. albicans wild-type (WT) isolates with 3 mg/kg and for wild-type isolates of the other species with 5 mg/kg. L-AMB was four- to eightfold less active against the included non-C. albicans species than C. albicans. A standard 3-mg/kg dose is pharmacodynamically sufficient for C. albicans whereas our data suggest that 5 mg/kg may be recommendable for the included non-C. albicans species.

Evaluation of the Vitek 2 system for antifungal susceptibility testing of Candida auris using a representative international panel of clinical isolates: overestimation of amphotericin B resistance and underestimation of fluconazole resistance.

Although the Vitek 2 system is broadly used for antifungal susceptibility testing of Candida spp., its performance against Candida auris has been assessed using limited number of isolates recovered from restricted geographic areas. We therefore compared Vitek 2 system with the reference Clinical and Laboratory Standards Institute (CLSI) broth microdilution method using an international collection of 100 C. auris isolates belonging to different clades. The agreement ±1 twofold dilution between the two methods and the categorical agreement (CA) based on the Centers for Disease Control and Prevention's (CDC's) tentative resistance breakpoints and Vitek 2-specific wild-type upper limit values (WT-ULVs) were determined. The CLSI-Vitek 2 agreement was poor for 5-flucytosine (0%), fluconazole (16%), and amphotericin B (29%), and moderate for voriconazole (61%), micafungin (67%), and caspofungin (81%). Significant interpretation errors were recorded using the CDC breakpoints for amphotericin B (31% CA, 69% major errors; MaEs) and fluconazole (69% CA, 31% very major errors; VmEs), but not for echinocandins (99% CA, 1% MaEs for both micafungin and caspofungin) for which the Vitek 2 allowed correct categorization of echinocandin-resistant FKS1 mutant isolates. Discrepancies were reduced when the Vitek 2 WT-ULV of 16 mg/L for amphotericin B (98% CA, 2% MaEs) and of 4 mg/L for fluconazole (96% CA, 1% MaEs, 3% VmEs) were used. In conclusion, the Vitek 2 system performed well for echinocandin susceptibility testing of C .auris. Resistance to fluconazole was underestimated whereas resistance to amphotericin B was overestimated using the CDC breakpoints of ≥32 and ≥2 mg/L, respectively. Vitek 2 minimun inhibitory concentrations (MICs) >4 mg/L indicated resistance to fluconazole and Vitek 2 MICs ≤16 mg/L indicated non-resistance to amphotericin B.

A new PK/PD target for assessing efficacy of micafungin against Candida parapsilosis.

BACKGROUND: Pharmacokinetic/pharmacodynamic (PK/PD) targets of echinocandins failed to support current clinical breakpoints of Candida parapsilosis as the PTA is low for susceptible isolates despite the good clinical efficacy of echinocandins against these infections. We therefore investigated the effect of micafungin against C. parapsilosis using an in vitro PK/PD in the presence of 10% human serum. METHODS: Three susceptible (MIC = 0.5-2 mg/L) and one resistant (MIC > 8 mg/L) C. parapsilosis sensu stricto isolates were tested at two different inocula (104 and 103 cfu/mL) simulating micafungin human exposures in RPMI and in RPMI + 10% pooled human serum. The exposure-effect relationship tAUC0-24/MIC was described and different PK/PD targets were determined in order to calculate the PTA for the standard 100 mg IV q24h dose. RESULTS: A maximal effect was found at fCmax ≥ 4 mg/L in RPMI and tCmax ≥ 64 mg/L (fCmax = 0.08 mg/L) in the presence of serum for which in vitro PK/PD targets were 50 times lower. Stasis in the presence of serum was found at 272-240 tAUC0-24/MIC, close to the clinical PK/PD target (285 tAUC/MIC), validating the in vitro model. However, the PTA was low for susceptible isolates with EUCAST/CLSI MICs ≤ 2 mg/L. Among the different PK/PD targets investigated, the PK/PD target 28 tAUC/MIC associated with 10% of maximal effect with the low inoculum resulted in PTAs ≥ 95% for susceptible isolates with EUCAST/CLSI MICs ≤ 2 mg/L. CONCLUSIONS: A new PK/PD target was found for micafungin and C. parapsilosis that supports the current clinical breakpoint. This target could be used for assessing echinocandin efficacy against C. parapsilosis.

Sustained cell-mediated but not humoral responses in rituximab-treated rheumatic patients after vaccination against SARS-CoV-2.

OBJECTIVES: B-cell depleting monoclonal antibodies are associated with increased COVID-19 severity and impaired immune response to vaccination. We aimed to assess the humoral and cell mediated (CMI) immune response after SARS-CoV-2 vaccination in rituximab (RTX)-treated rheumatic patients. METHODS: Serum and whole blood samples were collected from RTX-treated rheumatic patients 3-6 months after last vaccination against SARS-CoV-2. Serum was tested by ELISA for quantitative detection of anti-spike SARS-CoV-2 IgG. Cell-mediated variant-specific SARS-CoV-2 immunity (CMI) was assessed by interferon-γ release assay Covi-FERON FIA. Patients were interviewed for breakthrough COVID-19 infection (BTI) 3 months post sampling. RESULTS: Sixty patients were studied after a median (IQR) of 179 (117-221.5) days from last vaccine to sampling. Forty (66.7%) patients had positive Covi-FERON and 23 (38.3%) had detectable anti-spike IgG. Covi-FERON positive patients had lower median RTX cumulative dose [6 (4-10.75) vs 11 (6.75-14.75) grams, (P = 0.019)]. Patients with positive anti-spike IgG had received fewer RTX cycles [2 (2-4) vs 6 (4-8), P = 0.002] and cumulative dose [4 (3-7) vs 10 (6.25-13) grams, P = 0.002] and had shorter time from last vaccination to sampling [140 (76-199) vs 192 (128-230) days, P = 0.047]. Thirty-seven percent were positive only for Covi-FERON and 7% only for anti-spike IgG. Twenty (33.3%) BTI occurred post sampling, exclusively during Omicron variant predominance. The proportion of patients with CMI response against Delta variant was lower in patients who experienced BTI (25% vs 55%, P = 0.03). CONCLUSIONS: Four out of ten RTX-treated vaccinated patients show lasting cell-mediated immune response despite undetectable anti-spike antibodies. Cumulative RTX dose affects both humoral and cell-mediated responses to SARS-CoV-2 vaccines. Cell-mediated immune responses call for attention as a vaccine efficacy marker against SARS-CoV-2.

Multidrug-resistant organism bloodstream infection and hospital acquisition among inpatients in three tertiary Greek hospitals during the COVID-19 era.

From 2019 (pre-COVID-19) to 2022 (COVID-19 years), three tertiary Greek hospitals monitored MDRO bloodstream infection (BSI) and hospital acquisition relying on laboratory data. Surveillance covered carbapenem-resistant Enterobacterales (CRE), Acinetobacter baumannii (CRAB), Pseudomonas aeruginosa (CRPA), vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA), in intensive care units (ICUs) and non-ICUs. Non-ICUs experienced significant increases in CRE, CRAB and VRE during the pandemic. In ICUs, CRE increased in 2021, CRAB in 2020 and 2021, and VRE in 2021 and 2022. KPC predominated among CRE. MDRO BSI and hospital acquisition incidence rates increased, driven by CRE and CRAB.

Increase in candidemia cases and emergence of fluconazole-resistant Candida parapsilosis and C. auris isolates in a tertiary care academic hospital during the COVID-19 pandemic, Greece, 2020 to 2023.

BackgroundThe COVID-19 pandemic and the emergence of Candida auris have changed the epidemiological landscape of candidaemia worldwide.AimWe compared the epidemiological trends of candidaemia in a Greek tertiary academic hospital before (2009-2018) and during the early COVID-19 (2020-2021) and late COVID-19/early post-pandemic (2022-2023) era.MethodsIncidence rates, species distribution, antifungal susceptibility profile and antifungal consumption were recorded, and one-way ANOVA or Fisher's exact test performed. Species were identified by MALDI-ToF MS, and in vitro susceptibility determined with CLSI M27-Ed4 for C. auris and the EUCAST-E.DEF 7.3.2 for other Candida spp.ResultsIn total, 370 candidaemia episodes were recorded during the COVID-19 pandemic. Infection incidence (2.0 episodes/10,000 hospital bed days before, 3.9 during the early and 5.1 during the late COVID-19 era, p < 0.0001), C. auris (0%, 9% and 33%, p < 0.0001) and fluconazole-resistant C. parapsilosis species complex (SC) (20%, 24% and 33%, p = 0.06) infections increased over time, with the latter not associated with increase in fluconazole/voriconazole consumption. A significant increase over time was observed in fluconazole-resistant isolates regardless of species (8%, 17% and 41%, p < 0.0001). Resistance to amphotericin B or echinocandins was not recorded, with the exception of a single pan-echinocandin-resistant C. auris strain.ConclusionCandidaemia incidence nearly tripled during the COVID-19 era, with C. auris among the major causative agents and increasing fluconazole resistance in C. parapsilosis SC. Almost half of Candida isolates were fluconazole-resistant, underscoring the need for increased awareness and strict implementation of infection control measures.

Multicenter Evaluation of the BIOFIRE Blood Culture Identification 2 Panel for Detection of Bacteria, Yeasts, and Antimicrobial Resistance Genes in Positive Blood Culture Samples.

Diagnostic tools that can rapidly identify and characterize microbes growing in blood cultures are important components of clinical microbiology practice because they help to provide timely information that can be used to optimize patient management. This publication describes the bioMérieux BIOFIRE Blood Culture Identification 2 (BCID2) Panel clinical study that was submitted to the U.S. Food & Drug Administration. Results obtained with the BIOFIRE BCID2 Panel were compared to standard-of-care (SoC) results, sequencing results, PCR results, and reference laboratory antimicrobial susceptibility testing results to evaluate the accuracy of its performance. Results for 1,093 retrospectively and prospectively collected positive blood culture samples were initially enrolled, and 1,074 samples met the study criteria and were included in the final analyses. The BIOFIRE BCID2 Panel demonstrated an overall sensitivity of 98.9% (1,712/1,731) and an overall specificity of 99.6% (33,592/33,711) for Gram-positive bacteria, Gram-negative bacteria and yeast targets which the panel is designed to detect. One hundred eighteen off-panel organisms, which the BIOFIRE BCID2 Panel is not designed to detect, were identified by SoC in 10.6% (114/1,074) of samples. The BIOFIRE BCID2 Panel also demonstrated an overall positive percent agreement (PPA) of 97.9% (325/332) and an overall negative percent agreement (NPA) of 99.9% (2,465/2,767) for antimicrobial resistance determinants which the panel is designed to detect. The presence or absence of resistance markers in Enterobacterales correlated closely with phenotypic susceptibility and resistance. We conclude that the BIOFIRE BCID2 Panel produced accurate results in this clinical trial.

Optimization of the EUCAST reference broth microdilution method for echinocandin susceptibility testing of Aspergillus fumigatus.

BACKGROUND: Because of the high inoculum (105 cfu/mL) used in the EUCAST susceptibility testing of Aspergillus spp., determination of the minimal effective concentration (MEC) of echinocandins is challenging as the morphological differences are subtle. METHODS: The MECs of 10 WT and 4 non-WT Aspergillus fumigatus isolates were determined with the EUCAST E.Def 9.4. Plates were inoculated with increasing inocula (102-105 cfu/mL) and after 24 and 48 h of incubation, MECs were determined macroscopically (magnifying mirror) and microscopically (inverted microscope) by two observers, spectrophotometrically (OD at 405 nm) and colorimetrically (absorbance at 450/630 nm after 2 h incubation with 400 mg/L XTT/6.25 µM menadione). The interobserver (between observers)/intermethod (compared with the microscopic method) essential agreement (EA, ±1 2-fold dilution) and categorical agreement (CA) were determined for each inoculum. RESULTS: Echinocandin-induced microscopic hyphal alterations or macroscopic changes in turbidity were subtle with a 105 cfu/mL inoculum compared with the lower inocula of 103 and 102 cfu/mL, where more distinct changes in turbidity and formation of characteristic rosettes were obvious at the MEC after 48 h. A 105 cfu/mL inoculum resulted in wider MEC distributions (3-6 dilutions) and lower interobserver EA (69%), macroscopic-microscopic EA (26%) and CA (71%) compared with a 103 cfu/mL inoculum (2-3 dilutions, 100%, 100% and 100%, respectively). Spectrophotometric readings using a 103 cfu/mL inoculum showed good EA (57-93%) and excellent CA (86%-100%), while the XTT assay demonstrated excellent EA (93%) and CA (100%). CONCLUSIONS: A 48 h incubation using a 103 cfu/mL inoculum improved echinocandin MEC determination for A. fumigatus with the EUCAST method, while the colorimetric assay could allow automation.

Impact of a 4-year antimicrobial stewardship program implemented in a Greek tertiary hospital.

This study aimed to investigate the effects of a 4-year antibiotic stewardship program (ASP) in a tertiary hospital. We monitored data for 2015 (pre-intervention) and 2016-2019 (post-intervention) about antibiotic consumption (DDD/100 bed days), Clostridioides difficile infections (CDIs), resistance rates, length of stay (LOS), and annual antibiotic costs. Significant reductions were observed for total antibiotics/colistin/carbapenems/quinolones/tigecycline consumption and resistance rates of Pseudomonas aeruginosa, Klebsiella pneumoniae, and vancomycin-resistant enterococci. Considerable reductions occurred for LOS (4.18 [2015]/3.0 [2019] days), CDIs (1.47 [2015]/0.86 [2019] per 1000 patients), antibiotic cost/patient (39.45€ [2015]/23.69€ [2019]). The ASP was successful in reducing antibiotic consumption, antibiotic costs, length of hospital stay, and CDIs.

Can bronchial secretion cultures identify the etiologic agent of COVID-19-associated pulmonary aspergillosis in ICU patients? Comparison with a species-specific Aspergillus PCR in serum.

Aspergillus spp. isolated from non-BAL cultures of coronavirus disease 2019 (COVID-19)-associated pulmonary aspergillosis (CAPA) patients may reflect colonization rather than infection. Sera (n = 181) from 49 adult ICU CAPA patients (24 probable and 25 possible CAPA) with bronchial secretions (BS) culture positive for Aspergillus spp. were collected and tested for Aspergillus DNA detection by species-specific real-time PCR. Overall, 30/49 (61%) patients were PCR positive. BS culture/serum PCR agreement was moderate (21/30; 70%). Based on serum PCR positive patients, all CAPAs were due to A. fumigatus (80%), A. flavus (10%), and A. terreus (10%). No A. niger/A. nidulans or mixed infections were found despite positive BS cultures.

Discordant results were observed between bronchial secretion cultures and species-specific serum PCR (30%) with A. fumigatus being by far the most common etiological agent of CAPA (80%). No A. niger/A. nidulans or mixed infections were found despite positive cultures.

Comparative Pharmacodynamics of Echinocandins against Aspergillus fumigatus Using an In Vitro Pharmacokinetic/Pharmacodynamic Model That Correlates with Clinical Response to Caspofungin Therapy: Is There a Place for Dose Optimization?

Echinocandins have been used as primary therapy of invasive aspergillosis (IA), with suboptimal results at standard dosing. Here, we explored the efficacy of dose escalation in a validated in vitro pharmacokinetic/pharmacodynamic (PK/PD) model. Six echinocandin wild-type (WT) and three non-WT A. fumigatus isolates were tested in an in vitro PK/PD model simulating anidulafungin, caspofungin, and micafungin exposures with a free drug maximum concentration (fCmax) of 0.01 to 16 mg/liter and a half-life (t1/2) of 8 to 22 h. The relationship between the area under the dosing interval time-free drug concentration curve (fAUC0-24)/minimum effective concentration (MEC) and % aberrant mycelium formation was analyzed. PK/PD indices associated with 50 to 99.99% maximal activity (EI50 to EI99.99) were correlated with the clinical outcome of a 50-mg/day standard dose of caspofungin. The probability of target attainment (PTA) was calculated for different dosing regimens of each echinocandin via Monte Carlo analysis. A sigmoidal PK/PD relationship was found for WT isolates with EI99 values of 766, 8.8, and 115 fAUC0-24/CLSI MEC for anidulafungin, caspofungin, and micafungin, respectively. No aberrant mycelia were observed for non-WT isolates, irrespective of their MEC and drug exposure. The EI99, EI99.9, and EI99.99 values corresponded to 2-, 3-, and 4-log10 formation of aberrant mycelia and correlated with survival, favorable, and complete response rates to caspofungin primary therapy in patients with IA. A very low PTA (<13%) was found for the standard doses of all echinocandins, whereas a PTA of ≥90% was found with 100 and 150 mg/day of caspofungin and 1,400 mg/day micafungin against WT isolates. For anidulafungin, the PTA for 1,500 mg/day was 10%. Among the three echinocandins, only caspofungin at 2 or 3 times the licensed dosing was associated with a high PTA. Caspofungin dose escalation might deserve clinical validation.

Phenotypic/Genotypic Profile of OXA-10-Like-Harboring, Carbapenem-Resistant Pseudomonas aeruginosa: Using Validated Pharmacokinetic/Pharmacodynamic In Vivo Models To Further Evaluate Enzyme Functionality and Clinical Implications.

In vitro MICs and in vivo pharmacodynamics of ceftazidime and cefepime human-simulated regimens (HSR) against modified carbapenem inactivation method (mCIM)-positive Pseudomonas aeruginosa isolates harboring different OXA-10-like subtypes were described. The murine thigh model assessed ceftazidime (2 g every 8 h [q8h] HSR) and cefepime (2 g and 1 g q8h HSR). Phenotypes were similar despite possessing OXA-10-like subtypes with differing spectra. Ceftazidime produced ≥1-log10 killing in all isolates. Cefepime activity was dose dependent and MIC driven. This approach may be useful in assessing the implications of ß-lactamase variants.

Elevated MICs of Susceptible Antipseudomonal Cephalosporins in Non-Carbapenemase-Producing, Carbapenem-Resistant Pseudomonas aeruginosa: Implications for Dose Optimization.

The present study evaluated the in vitro potency of ceftazidime and cefepime among carbapenem-resistant Pseudomonas aeruginosa isolates collected as part of a global surveillance program and assessed the pharmacodynamic implications using previously published population pharmacokinetics. When susceptible, MICs resulted at the high end of distribution for both ceftazidime and cefepime, thus 6 g/day was required to achieve optimal pharmacodynamic profiles. These findings should be considered in the clinic and for the application of CLSI susceptibility breakpoints.

Predominance of CTX-M-15-producing ST131 strains among ESBL-producing Escherichia coli isolated from asylum seekers in the Netherlands.

OBJECTIVES: Numerous studies show increased prevalence of MDR bacteria amongst asylum seekers, but data on the molecular profiles of such strains are limited. We aimed to evaluate the molecular profiles of ESBL-producing Escherichia coli (ESBL-E. coli) strains isolated from asylum seekers and investigate their phylogenetic relatedness. METHODS: WGS data of ESBL-E. coli isolates from asylum seekers, retrieved from 1 January to 31 December 2016, were analysed to assess MLST STs, fim types, phylogroups and resistance genes. Fifty-two ESBL-E. coli isolates from the Dutch-German border region were used for genome comparison purposes as a control group. RESULTS: Among 112 ESBL-E. coli isolates from asylum seekers, originating mostly from Syria (n = 40) and Iraq (n = 15), the majority belonged to ST131 (21.4%) and ST10 (17.0%). The predominant gene for ß-lactam resistance was blaCTX-M-15 (67.9%), followed by the often co-detected blaTEM-1B (39.3%). No mcr or carbapenemase genes were detected. The majority of the strains belonged to phylogroups B2 (38.4%) and A (32.1%), carrying fimH27 (25%) and fimH30 (19.6%). A core genome MLST minimum spanning tree did not reveal clusters containing strains from the asylum seekers and the control group. Five clusters were formed within the asylum seeker group, by strains isolated from people originating from different countries. CONCLUSIONS: The most frequently isolated clones in this study were isolated on a regular basis within the Dutch population before the increase in the asylum seeker population. No mcr- or carbapenemase-producing clones were detected among the asylum seeker population. Minor clustering was observed amongst the asylum seeker strains.

The ERACE-PA Global Surveillance Program: Ceftolozane/tazobactam and Ceftazidime/avibactam in vitro Activity against a Global Collection of Carbapenem-resistant Pseudomonas aeruginosa.

The cephalosporin-ß-lactamase-inhibitor-combinations, ceftolozane/tazobactam and ceftazidime/avibactam, have revolutionized treatment of carbapenem-resistant Pseudomonas aeruginosa (CR-PA). A contemporary assessment of their in vitro potency against a global CR-PA collection and an assessment of carbapenemase diversity are warranted. Isolates determined as CR-PA by the submitting site were collected from 2019-2021 (17 centers in 12 countries) during the ERACE-PA Global Surveillance Program. Broth microdilution MICs were assessed per CLSI standards for ceftolozane/tazobactam, ceftazidime/avibactam, ceftazidime, and cefepime. Phenotypic carbapenemase testing was conducted (modified carbapenem inactivation method (mCIM)). mCIM positive isolates underwent genotypic carbapenemase testing using the CarbaR, the CarbaR NxG, or whole genome sequencing. The MIC50/90 was reported as well as percent susceptible (CLSI and EUCAST interpretation). Of the 807 isolates, 265 (33%) tested carbapenemase-positive phenotypically. Of these, 228 (86%) were genotypically positive for a carbapenemase with the most common being VIM followed by GES. In the entire cohort of CR-PA, ceftolozane/tazobactam and ceftazidime/avibactam had MIC50/90 values of 2/ > 64 and 4/64 mg/L, respectively. Ceftazidime/avibactam was the most active agent with 72% susceptibility per CLSI compared with 63% for ceftolozane/tazobactam. For comparison, 46% of CR-PA were susceptible to ceftazidime and cefepime. Against carbapenemase-negative isolates, 88 and 91% of isolates were susceptible to ceftolozane/tazobactam and ceftazidime/avibactam, respectively. Ceftolozane/tazobactam and ceftazidime/avibactam remained highly active against carbapenem-resistant P. aeruginosa, particularly in the absence of carbapenemases. The contemporary ERACE-PA Global Program cohort with 33% carbapenemase positivity including diverse enzymology will be useful to assess therapeutic options in these clinically challenging organisms with limited therapies.

Epidemiological Trends of Fungemia in Greece with a Focus on Candidemia during the Recent Financial Crisis: a 10-Year Survey in a Tertiary Care Academic Hospital and Review of Literature.

Updated information on the epidemiology of candidemia, particularly during severe socioeconomic events, is important for proper management of these infections. A systematic literature review on candidemia in Greece and a retrospective surveillance study were conducted in a tertiary university hospital during the years of the recent financial crisis (2009 to 2018) in order to assess changes in incidence rates, patient characteristics, species distribution, antifungal susceptibilities, and drug consumption. The average annual incidence of 429 candidemic episodes was 2.03/10,000 bed days, with 9.88 in adult intensive care units (ICUs), 1.74 in surgical wards, and 1.81 in internal medicine wards, where a significant increase was observed (1.15, 1.85, and 2.23/10,000 bed days in 2009 to 2011, 2012 to 2014, and 2015 to 2018, respectively; P = 0.004). Candida albicans was the most common species (41%), followed by Candida parapsilosis species complex [SC] (37%), Candida glabrata SC (11%), Candida tropicalis (7%), Candida krusei (1%), and other rare Candida spp. (3%). Mixed infections were found in 20/429 (4.7%) cases, while 33 (7%) cases were due to non-Candida spp. Overall, 44/311 (14%) isolates were resistant/non-wild type (WT) to the nine antifungals tested, with 23/113 (20%) C. parapsilosis SC and 2/34 (6%) C. glabrata SC isolates being resistant to fluconazole (1 panechinocandin and 2 panazole resistant). All isolates were susceptible/WT to amphotericin B and flucytosine. While the overall consumption of antifungals diminished (P = 0.02), with a mean of 17.93 defined daily doses (DDD)/100 bed days, increased micafungin use was correlated with the rise in C. parapsilosis SC (P = 0.04). A significant increase of candidemia in internal medicine wards and of C. parapsilosis SC infections was found during the years of financial crisis. Although resistance rates remain low (<14%), fluconazole-resistant C. parapsilosis SC and multidrug-resistant C. glabrata SC isolates are of major concern.

Nationwide surveillance of azole-resistant Aspergillus fumigatus environmental isolates in Greece: detection of pan-azole resistance associated with the TR46/Y121F/T289A cyp51A mutation.

BACKGROUND: Acquired azole resistance (AR) in Aspergillus fumigatus emphasizes the importance of the One Health multisectorial approach. The prevalence of azole-resistant A. fumigatus in the environment of Greece is unknown. METHODS: Between October 2016 and September 2017, a total of 716 soil samples were collected from 23 provinces and screened for AR using azole-containing agar plates. Recovered isolates were macro-/microscopically identified and colonies were counted. Azole susceptibility testing of A. fumigatus species complex (SC) isolates was performed (EUCAST E.DEF9.3.1). Azole-resistant A. fumigatus isolates were subjected to confirmatory molecular identification and sequencing of the cyp51A gene. RESULTS: No yeasts were recovered, while multiple moulds grew on 695 (97%) samples. Overall, zygomycetes (most non-Mucor genera) grew on 432 (60%) samples, while Aspergillus spp. grew on 500 (70%) [410 (57%) Aspergillus niger SC; 120 (17%) Aspergillus terreus SC; 101 (14%) A. fumigatus SC; 34 (5%) Aspergillus flavus SC]. The mean ± SD soil load of Aspergillus spp. was 2.23 ±âŸ0.41 log10 cfu/g (no differences among species). No azole-resistant non-A. fumigatus spp. isolate was detected. Itraconazole, voriconazole, isavuconazole and posaconazole MIC50/MIC90 (MIC range) of A. fumigatus SC strains were 0.25/0.5 (0.25 to >8), 0.5/1 (0.25 to >8), 1/1 (0.125 to >8) and 0.06/0.125 (0.06-1) mg/L, respectively. Overall, 1/500 (0.2%) of Aspergillus isolates, and 1/101 (1%) of A. fumigatus SC isolates, was pan-azole-resistant (itraconazole, voriconazole, isavuconazole and posaconazole MIC >8, >8, >8 and 1 mg/L, respectively). The resistant isolate was recovered from organically grown raisin grapes treated with homemade compost and it was an A. fumigatus sensu stricto isolate harbouring the TR46/Y121F/T289A mutation. The soil's load was higher compared with azole-susceptible strains (3.74 versus 2.09 log10 cfu/g). CONCLUSIONS: This is the first known report of environmental pan-azole-resistant A. fumigatus in Greece. Since data on Greek clinical isolates are lacking, this finding must alarm the systematic local surveillance of AR in medical settings.

In Vitro and In Vivo Exposure-Effect Relationship of Liposomal Amphotericin B against Aspergillus fumigatus.

In vitro pharmacokinetic/pharmacodynamic data of liposomal amphotericin B (L-AMB) were compared with animal data from neutropenic and nonneutropenic models of azole-susceptible and azole-resistant invasive aspergillosis. L-AMB was equally effective. The in vitro fCmax (maximum concentration of free drug)/MIC ratio associated with 50% of maximal activity was 0.31 (0.29 to 0.33), similar to that in neutropenic but not nonneutropenic mice (0.11 [0.06 to 0.20]). Simulation analysis indicated that standard L-AMB doses (1 to 3 mg/kg) are adequate for nonneutropenic patients, but higher doses (7.5 to 10 mg/kg) may be required for neutropenic patients for Aspergillus fumigatus isolates with MICs of 0.5 to 1 mg/liter.

Triple combination of meropenem, colistin and tigecycline was bactericidal in a dynamic model despite mere additive interactions in chequerboard assays against carbapenemase-producing Klebsiella pneumoniae isolates.

Background: Combination schemes are commonly used for the treatment of infections due to carbapenemase-producing Klebsiella pneumoniae (CP-Kp). We therefore investigated the in vitro effectiveness of double and triple combinations of meropenem, colistin and tigecycline against CP-Kp isolates with different resistance mechanisms in a static broth microdilution model and a pharmacokinetic-pharmacodynamic model. Methods: One WT isolate and seven CP-Kp isolates with different carbapenem resistance mechanisms and increasing MICs of meropenem (4-512 mg/L), colistin (0.5-32 mg/L) and tigecycline (0.25-4 mg/L) were tested with a 3D chequerboard microdilution method. Combinations were then assessed in an in vitro pharmacokinetic-pharmacodynamic model simulating 50 and 100 mg of tigecycline q12h as a 1 h infusion, 4.5 million units of colistin q12h as a 1 h infusion and 1 g of meropenem q8h as 1 and 0.5 h infusions for 2 days. Results: In the chequerboard assay, interactions within the triple combination were mainly additive with a median (range) fractional inhibitory index of 0.66 (0.22-1.26). In the dynamic model, meropenem alone was bactericidal against isolates with MICs up to 4 mg/L, whereas bactericidal activity was found with the double combination meropenem + colistin and the triple combination meropenem + colistin + tigecycline against CP-Kp isolates with meropenem MICs of 16 and 256 mg/L, respectively. A high dose (100 mg) of tigecycline and a prolonged infusion (1 h) of meropenem increased the efficacy of the triple combination. Conclusions: Despite the merely additive interactions in the chequerboard assay, the triple combination of meropenem, tigecycline and colistin was bactericidal in the dynamic model against highly resistant CP-Kp isolates. This effect was more pronounced if prolonged infusion of meropenem and high tigecycline dosing were used.