Postgenomic Bioinformatic Analysis of Nucleic Acid Sequences Expressed in the Salivary Gland Epithelial Cells of Primary Sjögren's Syndrome Patients in Search of Microorganisms and Endogenous Retroviruses.

Several previous studies from our laboratory have indicated that the salivary gland epithelia of primary Sjögren's syndrome (SS) patients are not only the target of autoimmune immune responses, but also key instigators of the chronic salivary gland inflammatory infiltrates of patients. In particular, the comparative analysis of salivary gland tissue specimens and of in-vitro cultured non-neoplastic salivary gland epithelial cell lines (SGEC, of ductal type) from SS-patients and non-SS disease-controls, have unequivocally highlighted the presence of intrinsic activation in the ductal epithelia of SS-patients and of aberrant expression of inflammagenic molecules thereof, that correlate with the severity of local histopathologic changes, as well as of systemic manifestations of the disease. In the same context, we have recently shown that the ductal epithelia of SS-patients manifest cell-autonomous activation of the AIM2 inflammasome owing to the presence of aberrant cytoplasmic accumulations of damaged DNA. These findings not only provide a mechanistic explanation for the intrinsic activation and inflammatory status of SS ductal epithelia, but may also point towards the putative instigating role of an exogenous or endogenous agent (i.e., a micro-organism or an endogenous retrovirus, respectively). On this basis and to further explore the nature of epithelial cell-intrinsic activation in SS, the present proposal aims to investigate the expression of endogenous retroviral and/or non-human nucleic acid sequences of microbial origin in the ductal salivary gland epithelia of SS-patients, using metagenomic analysis of high throughput DNA and RNA genome sequencing data, which will be obtained from SGEC lines derived from SS-patients and disease-controls.

Molecular epidemiology of noroviruses in children in South Greece, 2013-2015.

Noroviruses constitute the leading cause of acute, nonbacterial gastroenteritis that affects both children and adults in healthcare and community settings. The current study attempted to provide insight on the molecular epidemiology of noroviruses in children in South Greece. Genotypic characterization of 69 norovirus strains detected in stool samples from children with gastroenteritis during a period of 30 months (January 2013 to June 2015) was performed on the basis of ORF2 (VP1 capsid) gene sequences. The results revealed the circulation of a diverse variety of norovirus genotypes. GII.4 was the predominant genotype (74%), followed by GII.2 (8.7%), GII.3 (5.8%), GII.6 (2.9%), GI.2 (2.9%), and four strains identified as GII.1, GII.7, GII.8, and GII.13, respectively. Phylogenetic analysis showed that most of the strains were closely associated with norovirus strains that circulated globally either in outbreaks and sporadic cases of gastroenteritis or in the environment during the last 4 years. Οf the GII.4 strains, 80.4% were detected between January 2013 and February 2014, indicating a possible ongoing epidemic. The incidence of other genotypes remained constant throughout the study period. Genotypic and phylogenetic analysis showed the predominance of the "Sydney 2012" variant among the GII.4 strains, whereas one GII.4 strain was identified as a "New Orleans 2009" variant. Five GII.4 strains showed significant nucleotide and amino acid sequence divergence from either the "Sydney 2012" or the "New Orleans 2009" variant, and these divergent strains might represent an emerging GII.4 variant.

Point-prevalence survey of healthcare facility-onset healthcare-associated Clostridium difficile infection in Greek hospitals outside the intensive care unit: The C. DEFINE study.

BACKGROUND: The correlation of Clostridium difficile infection (CDI) with in-hospital morbidity is important in hospital settings where broad-spectrum antimicrobial agents are routinely used, such as in Greece. The C. DEFINE study aimed to assess point-prevalence of CDI in Greece during two study periods in 2013. METHODS: There were two study periods consisting of a single day in March and another in October 2013. Stool samples from all patients hospitalized outside the ICU aged ≥18 years old with diarrhea on each day in 21 and 25 hospitals, respectively, were tested for CDI. Samples were tested for the presence of glutamate dehydrogenase antigen (GDH) and toxins A/B of C. difficile; samples positive for GDH and negative for toxins were further tested by culture and PCR for the presence of toxin genes. An analysis was performed to identify potential risk factors for CDI among patients with diarrhea. RESULTS: 5,536 and 6,523 patients were screened during the first and second study periods, respectively. The respective point-prevalence of CDI in all patients was 5.6 and 3.9 per 10,000 patient bed-days whereas the proportion of CDI among patients with diarrhea was 17% and 14.3%. Logistic regression analysis revealed that solid tumor malignancy [odds ratio (OR) 2.69, 95% confidence interval (CI): 1.18-6.15, p = 0.019] and antimicrobial administration (OR 3.61, 95% CI: 1.03-12.76, p = 0.045) were independent risk factors for CDI development. Charlson's Comorbidity Index (CCI) >6 was also found as a risk factor of marginal statistical significance (OR 2.24, 95% CI: 0.98-5.10). Median time to CDI from hospital admission was shorter with the presence of solid tumor malignancy (3 vs 5 days; p = 0.002) and of CCI >6 (4 vs 6 days, p = 0.009). CONCLUSIONS: The point-prevalence of CDI in Greek hospitals was consistent among cases of diarrhea over a 6-month period. Major risk factors were antimicrobial use, solid tumor malignancy and a CCI score >6.

Impact of bacterial load on pharmacodynamics and susceptibility breakpoints for tigecycline and Klebsiella pneumoniae.

OBJECTIVES: In the absence of other therapeutic options, tigecycline is used to treat bloodstream infections and pneumonia caused by carbapenemase-producing Klebsiella pneumoniae (CP-Kp). In this study, the standard and high tigecycline dosing regimens were simulated and tested against different inocula of CP-Kp isolates in an in vitro pharmacokinetic (PK)/pharmacodynamic (PD) model. METHODS: Four susceptible isolates (EUCAST MICs of 0.125-1 mg/L) and two intermediately susceptible CP-Kp clinical isolates (MICs of 2 mg/L) were tested at three different inocula (107, 105 and 103 cfu/mL), simulating tigecycline serum and lung fCmax concentrations of 0.15 and 1.5 mg/L, respectively, of 50 mg tigecycline every 12 h for 48 h. The exposure-effect relationships were described and the probability of target attainment was calculated for each inoculum in order to determine PK/PD susceptibility breakpoints. RESULTS: No cfu reduction was observed at serum concentrations. At lung concentrations and low inocula, a bacteriostatic and killing effect was found for isolates with MICs of 0.25 and 0.125 mg/L, respectively. The fAUC0-24/MIC (tAUC0-24/MIC) associated with half-maximal activity was 16 (150) with 103 cfu/mL, 28 (239) with 105 cfu/mL and 79 (590) with 107 cfu/mL. A PK/PD susceptibility breakpoint of ≤0.06 and ≤0.125 mg/L for bacteraemia with ≤101 cfu/mL and ≤0.25 and ≤0.5 mg/L for pneumonia with ≤103 cfu/g was determined for the standard tigecycline dose of 50 mg and the higher dose of 100 mg, respectively. CONCLUSIONS: Tigecycline monotherapy with either 50 or 100 mg would not be sufficient for most patients with bacteraemia, though the higher dose of 100 mg could be effective for patients with pneumonia with low bacterial load.

Concurrent Autochthonous Malaria Caused by Plasmodium vivax in Father and Son in Greece.

We report the case of a 12-year-old child who was admitted to our Department, with 7 days' history of high fever and splenomegaly. His father had similar symptoms starting on the same day. A rapid test and microscopy for malaria yielded a positive result for Plasmodium vivax Antimalarial therapy was initiated. He developed methemoglobinemia treated with ascorbic acid and had uneventful recovery.

Dose optimization of voriconazole/anidulafungin combination against Aspergillus fumigatus using an in vitro pharmacokinetic/pharmacodynamic model and response surface analysis: clinical implications for azole-resistant aspergillosis.

BACKGROUND: Combination therapy of voriconazole with an echinocandin is often employed in order to increase the efficacy of voriconazole monotherapy. METHODS: Four clinical Aspergillus fumigatus isolates with different in vitro susceptibilities to voriconazole (MIC 0.125-2 mg/L) and anidulafungin (MEC 0.008-0.016 mg/L) were tested in an in vitro pharmacokinetic/pharmacodynamic model simulating human serum concentrations of standard dosages of voriconazole and anidulafungin. Fungal growth was assessed using galactomannan production and quantitative PCR. Drug concentrations were determined with bioassays. Pharmacodynamic interactions were assessed using Bliss independence analysis (BI) and Loewe additivity-based canonical mixture response-surface non-linear regression analysis (LA). Probability of target attainment (PTA) was estimated with Monte Carlo analysis for different doses of anidulafungin (25, 50 and 100 mg) and azole resistance rates (5%-25%). RESULTS: Synergy [BI 51% (8%-80%), LA 0.63 (0.38-0.79)] was found at low anidulafungin (fCmax/MEC <10) and voriconazole (fAUC/MIC <10) exposures, whereas antagonism [BI 12% (5%-18%, LA 1.12 (1.04-4.6)] was found at higher drug exposures. The largest increase in PTA was found with 25 mg of anidulafungin and voriconazole MIC distributions with high (>10%) resistance rates. PTAs for isolates with voriconazole MICs of 1, 2 and 4 mg/L was 78%, 12% and 0% with voriconazole monotherapy and 96%-100%, 68%-82% and 9%-20% with combination therapy, respectively. Optimal activity was associated with a voriconazole tCmin/MIC ratio of 1.5 for monotherapy and 0.75 for combination therapy. CONCLUSIONS: The present study indicated that the combination of voriconazole with low-dose anidulafungin may increase the efficacy and reduce the cost and potential toxicity of antifungal therapy, particularly against azole-resistant A. fumigatus isolates and in patients with subtherapeutic serum levels. This hypothesis warrants further in vivo verification.

Comparison of Short Versus Prolonged Infusion of Standard Dose of Meropenem Against Carbapenemase-Producing Klebsiella pneumoniae Isolates in Different Patient Groups: A Pharmacokinetic-Pharmacodynamic Approach.

Dose optimization is required to increase carbapenem's efficacy against carbapenemase-producing isolates. Four clinical Klebsiella pneumoniae isolates were used: one susceptible to meropenem with minimum inhibitory concentration (MIC) 0.031 mg/L and 3 verona integron-borne metallo bete-lactamase-1-producing isolates with MICs 8, 16, and 128 mg/L. The human pharmacokinetics of short (0.5-h) and prolonged (3-h) infusion regimens of 1 g meropenem every 8 h were simulated in an in vitro pharmacokinetic-pharmacodynamic model. Time-kill curves were constructed for each isolate and dosing regimen, and the %T > MIC associated with maximal bactericidal activity was estimated. The percentage of pharmacodynamic target attainment for isolates with different MICs was calculated for 350 ICU, surgical, and internal medicine patients. The isolates with MIC ≤8 mg/L were killed with both dosing regimens. The %T > MIC corresponding to maximal bactericidal activity was ∼40%. The percentages of target attainment were >90%, 61%-83%, 23%-33%, and <3% with the short infusion regimen and >90%, 98%-99%, 55%-79%, and <5% with the prolonged infusion regimen for isolates with MIC ≤2, 4, 8, and ≥16 mg/L, respectively. The lowest target attainment rates were observed for the ICU patients and the highest for internal medicine patients. The prolonged infusion regimen was more effective than the short infusion regimen against isolates with MIC 4-8 mg/L.

Bioartificial liver attenuates intestinal mucosa injury and gut barrier dysfunction after major hepatectomy: Study in a porcine model.

BACKGROUND: The aim of this study was to evaluate whether bioartificial liver support can attenuate gut mucosa injury in a porcine model of posthepatectomy liver dysfunction. METHODS: Posthepatectomy liver failure was induced in pigs combining major (70%) liver resection and ischemia/reperfusion injury. An ischemic period of 150 minutes was followed by reperfusion for 24 hours. Animals were divided randomly into 2 groups: a control group (n = 6) that received standard critical care and a bioartificial liver support group (Hepat, n = 6) that were subjected to extracorporeal liver support for 6 hours during reperfusion. Intestinal mucosal injury, bacterial translocation, and endotoxin translocation were evaluated in all animals. Intestinal mucosa was also evaluated with markers of oxidative injury and immunohistochemical staining for caspase 3. RESULTS: When compared with median values, the control group, animals in the Hepat group had a lesser intestinal mucosal injury score (4.0 [range:2.0-5.0] vs 1.0 [range:1.0-2.0]; P < .01), decreased bacterial translocation in the portal and the systemic circulation at 24 hours of reperfusion (P < .05), and decreased portal and systemic endotoxin levels at 24 hours (P < .05). At 24 hours after reperfusion, mucosal protein carbonyls and malondialdehyde levels were decreased in Hepat animals (0.57 nmol/mg [range:0.32-0.70] vs 0.33 nmol/mg [range:0.03-0.53] and 3.85 nmol/mg [range:3.01-6.43] vs 3.27 nmol/mg [range:1.46-3.55], respectively; P < .05). There was no difference in tissue caspase staining. CONCLUSION: Bioartificial liver support seems to attenuate intestinal mucosal injury and gut barrier dysfunction after major hepatectomy.

Bioassay for Determining Voriconazole Serum Levels in Patients Receiving Combination Therapy with Echinocandins.

Voriconazole levels were determined with high-performance liquid chromatography (HPLC) and a microbiological agar diffusion assay using a Candida parapsilosis isolate in 103 serum samples from an HPLC-tested external quality control program (n = 39), 21 patients receiving voriconazole monotherapy (n = 39), and 7 patients receiving combination therapy (n = 25). The results of the bioassay were correlated with the results obtained from the external quality control program samples and with the HPLC results in sera from patients on voriconazole monotherapy and on combination therapy with an echinocandin (Spearman's rank correlation coefficient [rs], > 0.93; mean ± standard error of the mean [SEM] % difference, <12% ± 3.8%).

Pharmacokinetic-pharmacodynamic modelling of meropenem against VIM-producing Klebsiella pneumoniae isolates: clinical implications.

VIM-producing Klebsiella pneumoniae isolates are usually associated with high MICs to carbapenems. Preclinical studies investigating the pharmacokinetic-pharmacodynamic (PK-PD) characteristics of carbapenems against these isolates are lacking. The in vitro antibacterial activity of meropenem against one WT and three VIM-producing K. pneumoniae clinical isolates (median MICs 0.031, 8, 16 and 128 mg l- 1) was studied in a dialysis-diffusion PK-PD model and verified in a thigh infection neutropenic animal model by testing selected strains and exposures. The in vitro PK-PD target associated with bactericidal activity was estimated and the target attainment for different dosing regimens was calculated with Monte Carlo analysis. The in vitro model was correlated with the in vivo data, with log10CFU/ml reduction of < 1 for the VIM-producing (MIC 16 mg l- 1) and >2 for the WT (MIC 0.031 mg l- 1) isolates, with %f T >MIC 25 and 100%, respectively. The in vitro bactericidal activity for all isolates was associated with 40 % f T>MIC and attained in >90% of cases with the standard 1 g q8 0.5 h infusion dosing regimen only for isolates with MICs up to 1 mg l- 1. For isolates with MICs of 2-8 mg l- 1, prolonged infusion regimens (4 h infusion q8 or 2 h infusion q4) of standard (1 g) and higher (2 g) doses or continuous infusion regimens (3-6 g) are required. For isolates with a MIC of 16 mg l- 1 the unconventional dosing regimen of 2 g as 2 h infusion q4 or 12 g continuous infusion will be required. Prolonged and continuous infusion regimens of meropenem may increase efficacy against VIM-producing K. pneumoniae isolates.

Evaluation of paper gradient concentration strips for antifungal combination testing of Candida spp.

In vitro combination testing with broth microdilution chequerboard (CHEQ) method is widely used although it is time-consuming, cumbersome and difficult to apply in routine setting of clinical microbiology laboratory. A new gradient concentration paper strip method, the Liofilchem(®) MIC test strips (MTS), provides an alternative easy and fast method enabling the simultaneous diffusion of both drugs in combination. We therefore tested a polyene+azole and an azole+echinocandin combination against 18 Candida isolates with the CHEQ method based on EUCAST guidelines and the MTS method in research and routine settings. Fractional inhibitory concentration (FIC) indices were calculated after 24 and 48 h of incubation based on complete and prominent (FIC-2) growth inhibition endpoints. Reproducibility and agreement within 1 twofold dilution was assessed. The FICs of the two methods were correlated quantitatively with t-test and Pearson analysis and qualitatively with Chi-squared test. The reproducibility of the CHEQ and MTS method was 88-100% and their agreement was 80% with 62-77% of MTS FICs being higher than the corresponding CHEQ FICs. A statistically significant Pearson correlation (r = 0.86, P = 0.0003) and association (χ(2) = 17.05, df = 4, P = 0.002) was found between MTS FIC and CHEQ FIC-2 after 24 h. Categorical agreement was 63% with no very major or major errors. All MTS synergistic interactions were also synergistic with the CHEQ method.

Activity of vancomycin, linezolid, and daptomycin against staphylococci and enterococci isolated in 5 Greek hospitals during a 5-year period (2008-2012).

The tendency of vancomycin, linezolid, and daptomycin MICs was investigated among 6920 staphylococci and enterococci during a 5-year period. Antimicrobial consumption was determined. Decrease of vancomycin MIC was detected associated with reduction in consumption. Linezolid and daptomycin remained active. An upward trend of linezolid MIC for methicillin-resistant staphylococci was observed.

Evaluation of the "Dip Effect" Phenomenon in Antifungal Susceptibility Testing of Candida spp. against Echinocandins by Use of Gradient Concentration Strips.

The "dip effect" phenomenon complicates antifungal susceptibility testing with gradient concentration strips. Of 60 Candida isolates tested with the three echinocandins, this phenomenon was observed only for caspofungin with most (>90%) Candida albicans, Candida glabrata, and Candida tropicalis isolates and for isolates with CLSI MICs of ≤0.25 mg/liter. In order to facilitate MIC determination, a practical approach was developed using the inhibition zones at 32, 8, 2, and 1 mg/liter, increasing the agreement with the CLSI method >86%.

Optimization of polyene-azole combination therapy against aspergillosis using an in vitro pharmacokinetic-pharmacodynamic model.

Although amphotericin B-azole combination therapy has traditionally been questioned due to potential antagonistic interactions, it is often used successfully to treat refractory invasive aspergillosis. So far, pharmacodynamic (PD) interactions have been assessed with conventional in vitro tests, which do not mimic human serum concentrations and animal models using limited doses. We therefore simulated the human serum concentration profiles of amphotericin B and voriconazole in an in vitro dialysis/diffusion closed pharmacokinetic-pharmacodynamic (PK-PD) model and studied the pharmacodynamic interactions against an azole-resistant and an azole-susceptible Aspergillus fumigatus isolate, using Bliss independence and canonical mixture response surface analyses. Amphotericin B dosing regimens with the drug administered every 24 h (q24h) were combined with voriconazole q12h dosing regimens. In vitro PK-PD combination data were then combined with human PK data by using Monte Carlo analysis. The target attainment rate and the serum concentration/MIC ratio were calculated for isolates with different MICs. Synergy (20 to 31%) was observed at low amphotericin B-high voriconazole exposures, whereas antagonism (-6 to -16%) was found at high amphotericin B-low voriconazole exposures for both isolates. Combination therapy resulted in 17 to 48% higher target attainment rates than those of monotherapy regimens for isolates with voriconazole/amphotericin B MICs of 1 to 4 mg/liter. Optimal activity was found for combination regimens with a 1.1 total minimum concentration of drug in serum (tCmin)/MIC ratio for voriconazole and a 0.5 total maximum concentration of drug in serum (tCmax)/MIC ratio for amphotericin B, whereas the equally effective monotherapy regimens required a voriconazole tCmin/MIC ratio of 1.8 and an amphotericin B tCmax/MIC ratio of 2.8. Amphotericin B-voriconazole combination regimens were more effective than monotherapy regimens. Therapeutic drug monitoring can be employed to optimize antifungal combination therapy with low-dose (≤0.6 mg/kg) amphotericin B-based combination regimens against resistant isolates for minimal toxicity.

Susceptibility breakpoints and target values for therapeutic drug monitoring of voriconazole and Aspergillus fumigatus in an in vitro pharmacokinetic/pharmacodynamic model.

BACKGROUND: Although voriconazole reached the bedside 10 years ago and became the standard care in the treatment of invasive aspergillosis, reliable clinical breakpoints are still in high demand. Moreover, this has increased due to the recent emergence of azole resistance. METHODS: Four clinical wild-type and non-wild-type A. fumigatus isolates with voriconazole CLSI MICs in the range of 0.125-2 mg/L were tested in an in vitro pharmacokinetic (PK)/pharmacodynamic (PD) model. Mouse PK was simulated and in vitro data were compared with in vivo outcome. Human PK was simulated and susceptibility breakpoints and trough levels required for optimal treatment were determined for the CLSI and EUCAST methods after 48 h and the gradient concentration MIC test strip (MTS) method after 24 h using the in vitro PK/PD relationship and Monte Carlo simulation. RESULTS: The in vitro PK/PD target (95% CI) associated with 50% of the maximal antifungal activity (EC50) was 28.61 (16.18-50.61), close to the in vivo EC50 of 14.67 (9.31-21.58) fAUC0-24/CLSI MIC. When human PK was simulated, the EC50 was 24.7 (17.9-35.6) fAUC0-12/CLSI MIC and it was associated with 6 week survival in clinical studies of invasive pulmonary aspergillosis. Target attainment rates were ≤5% (0%-24%), 42% (16%-58%), 68% (54%-75%) and ≥79% (73%-86%) for isolates with CLSI MICs ≥2, 1, 0.5 and ≤0.25 mg/L, respectively. A trough/CLSI MIC ratio of 2 was required for optimal treatment. The susceptible/intermediate/resistant breakpoints were determined to be 0.25/0.5-1/2 mg/L for CLSI, 0.5/1-2/4 mg/L for EUCAST and 0.25/0.375-1/1.5 mg/L for MTS. CONCLUSIONS: These susceptibility breakpoints and target values for therapeutic drug monitoring could be used to optimize voriconazole therapy against A. fumigatus.

Molecular characterization of Streptococcus agalactiae from vaginal colonization and neonatal infections: a 4-year multicenter study in Greece.

A multicenter collection comprising of 171 Streptococcus agalactiae isolates from pregnant women recovered between 2007 and 2010 and 46 from unmatched neonates with invasive infections was subjected to antimicrobial susceptibility testing and genetic characterization. High rates of erythromycin resistance (20.47%) were observed only in isolates from pregnant women. ST1 was dominant in the vaginal colonization, whereas the hypervirulent ST-17 clone was detected in 67.39% of neonatal infections.

Amphotericin B- and voriconazole-echinocandin combinations against Aspergillus spp.: Effect of serum on inhibitory and fungicidal interactions.

Antifungal combination therapy with voriconazole or amphotericin B and an echinocandin is often employed as primary or salvage therapy for management particularly of refractory aspergillosis. The pharmacodynamic interactions of amphotericin B- and voriconazole-based combinations with the three echinocandins caspofungin, micafungin, and anidulafungin in the presence of serum were tested against 15 Aspergillus fumigatus complex, A. flavus complex, and A. terreus complex isolates to assess both their growth-inhibitory and fungicidal activities. The in vitro activity of each drug alone and in combination at a 1:1 fixed concentration ratio was tested with a broth microdilution colorimetric method, and interactions were assessed by isobolographic analysis. Synergy was found for all amphotericin B- and voriconazole-based combinations, with amphotericin B-based combinations showing strong inhibitory synergistic interactions (interaction indices of 0.20 to 0.52) and with voriconazole-based combinations demonstrating strong fungicidal synergistic interactions (interaction indices of 0.10 to 0.29) (P < 0.001). Drug- and species-specific differences were found, with caspofungin and the A. fumigatus complex exhibiting the weakest synergistic interactions. In the presence of serum, the synergistic interactions were reduced in the order (from largest to smallest decrease) micafungin > anidulafungin > caspofungin, and A. flavus complex > A. fumigatus complex > A. terreus complex, resulting in additive interactions, particularly for inhibitory activities of amphotericin B-echinocandin combinations and fungicidal activities of voriconazole-echinocandin combinations. Drug- and species-specific differences were found in the presence of serum for inhibitory activities of antifungal drugs, with the lowest interaction indices being observed for amphotericin B-caspofungin (median, 0.77) and for the A. terreus complex (median, 0.56). The present in vitro data showed that serum had a major impact on synergistic interactions of amphotericin B-echinocandin and voriconazole-echinocandin combinations, resulting in additive interactions and explaining the indifferent outcomes usually observed in vivo.

Successful control of an echovirus 6 meningitis outbreak in a neonatal intensive care unit in central Greece.

We report an outbreak of echovirus 6 meningitis in a neonatal intensive care unit in central Greece from July to August 2011. The most probable source of the outbreak was a mother; during hospitalization, her neonate was initially infected, followed by 7 more. Stricter infection control measures were implemented, and no other cases have been observed.

Single-dose pharmacodynamics of amphotericin B against Aspergillus species in an in vitro pharmacokinetic/pharmacodynamic model.

Conventional MIC testing of amphotericin B results in narrow MIC ranges challenging the detection of resistant strains. In order to discern amphotericin B pharmacodynamics, the in vitro activity of amphotericin B was studied against Aspergillus isolates with the same MICs by using a new in vitro pharmacokinetic/pharmacodynamic (PK/PD) model that simulates amphotericin B human plasma levels. Clinical isolates of Aspergillus fumigatus, A. terreus, and A. flavus with the same Clinical and Laboratory Standards Institute modal MICs of 1 mg/liter were exposed to amphotericin B concentrations following the plasma concentration-time profile after single-bolus administration with C(max) values of 0.6, 1.2, 2.4, and 4.8 mg/liter. Fungal growth was monitored for up to 72 h based on galactomannan production. Complete growth inhibition was observed only against A. fumigatus with amphotericin B with a Cmax of ≥ 2.4 mg/liter. At the lower C(max) values 0.6 and 1.2 mg/liter, significant growth delays of 34 and 52 h were observed, respectively (P < 0.001). For A. flavus, there was no complete inhibition but a progressive growth delay of 1 to 50 h at an amphotericin B C(max) of 0.6 to 4.8 mg/liter (P < 0.001). For A. terreus, the growth delay was modest (up to 8 h) at all C(max)s (P < 0.05). The C(max) (95% confidence interval) associated with 50% activity for A. fumigatus was 0.60 (0.49 to 0.72) mg/liter, which was significantly lower than for A. flavus 3.06 (2.46 to 3.80) mg/liter and for A. terreus 7.90 (5.20 to 12.29) mg/liter (P < 0.001). A differential in vitro activity of amphotericin B was found among Aspergillus species despite the same MIC in the order A. fumigatus > A. flavus > A. terreus in the in vitro PK/PD model, possibly reflecting the different concentration- and time-dependent inhibitory/killing activities amphotericin B exerted against these species.