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Background The glycopeptide teicoplanin is considered first-line treatment for severe infections caused by Gram-positive bacteria. Individualized treatment of teicoplanin is gaining interest. As only protein-unbound drug is pharmacologically active, a sensitive assay measuring unbound and total teicoplanin is indispensable for pharmacological research and dose optimization. Objectives To develop and validate a UPLC-MS/MS method to quantify unbound and total teicoplanin in human serum. Methods The developed assay was validated according to the ICH guideline M10 on Bioanalytical Method Validation and study sample analysis. Unbound teicoplanin was obtained by ultrafiltration. The assay was cross-validated with a quantitative microsphere (QMS) immunoassay in a side-by-side comparison using 40 patient samples. Results With the developed and validated method, all main teicoplanin components (A2-1, A2-2/A2-3, A2-4/A2-5 and A3-1) can be quantified. Total run time was 5.5 min. Concentration range was 2.5–150 mg/L for total and 0.1–25 mg/L for unbound teicoplanin. Precision (coefficient of variation) and accuracy (bias) of total teicoplanin were 5.97% and 107%, respectively, and 7.17% and 108%, respectively, for unbound teicoplanin. Bland–Altman analysis showed total concentrations measured with the UPLC-MS/MS method were equivalent to the results of the QMS immunoassay. A total of 188 samples from 30 patients admitted to the ICU and haematology department were measured; total concentrations ranged between 2.92 and 98.5 mg/L, and unbound concentrations ranged between 0.37 and 30.7 mg/L. Conclusions The developed method provided rapid, precise and accurate measurement of unbound and total teicoplanin. The developed method is now routinely applied in pharmacological research and clinical practice. [ABSTRACT FROM AUTHOR]

Abstract: Ceftobiprole is a broad‐spectrum cephalosporin. The objective of this study was to test the hypothesis that the pharmacokinetics (PK) and exposure of ceftobiprole in Asian subjects are similar to those in non‐Asian subjects. Three approaches were followed. The first compared the individual PK estimates between the 2 subgroups derived from a population PK model previously built. Next, it was determined whether “Asian subject” was a significant covariate. Finally, a pharmacodynamic analysis was performed by comparing measures of exposure and target attainment. No significant differences were found between PK parameter estimates for Asian and non‐Asian subjects, with median values (range) for clearance of 4.82 L/h (2.12–10.47) and 4.97 L/h (0.493–20.6), respectively (P = .736). “Asian subject” was not a significant covariate in the population PK model. There were no significant differences between the measures of exposure. The geometric mean ratio for the fAUC was 1.022 (90%CI, 0.91–1.15), indicating bioequivalence. Taking a target of 60% coverage of the dose interval, more than 90% of the population in both subgroups was adequately exposed. This analysis demonstrated that there are no PK or pharmacodynamic differences between Asian and non‐Asian subjects for a ceftobiprole dose of 500 mg every 8 hours as a 2‐hour infusion. [ABSTRACT FROM AUTHOR]

Background: Antimicrobial use in livestock is one of the factors contributing to selection and spread of resistant microorganisms in the environment. National veterinary antimicrobial consumption monitoring programs are therefore in place in a number of countries in the European Union. However, due to differences in methodology, results on veterinary antimicrobial consumption from these national monitoring programs cannot be compared internationally. International comparison is highly needed to establish regulations on veterinary antimicrobial use and reducing antimicrobial resistance. The aim of this study was to assess differences in the outcomes on veterinary antimicrobial consumption by applying three different sets of nationally established animal defined daily dosages to the same antimicrobial drug delivery dataset of Dutch pigs in 2012. Methods: Delivery information for the complete Dutch pig sector for the year 2012 reported to the Netherlands Veterinary Medicines Authority (SDa) was analysed with three differently and nationally established animal defined daily dosages from the Netherlands and Denmark: the Defined Daily Dosage AnimalNL (DDDANL), the Animal Daily DosageDK (ADDDK) and Defined Animal Daily DosageDK (DADDDK). For each applied Dutch product equivalent, Danish products were identified based on authorization for pigs, active substance (including form), administration route, concentration and dosage regimen. Results: Consumption in number of ADDDK/Y was lower than in number of DDDANL/Y for sows/piglets and finisher pigs, with proportions of 83.3 % and 98.3 %. Use in number of DADDDKK/Y was even lower, 79.7 % for sows/piglets and 88.1 % for finisher pigs compared to number of DDDANL/Y. At therapeutic group level proportions of number of DADDDK/Y to number of DDDANL/Y were 63.6-150.4 % (sows/piglets) and 55.6-171.0 % (finisher pigs). Proportions were > 100 % for the polymyxines (sows/piglets 150.4 % and finisher pigs 149.9 %) and the macrolides/lincosamides (finisher pigs 171.0 %). Conclusions: Differences between nationally established animal defined daily dosages caused by different correction factors for long-acting products and national differences in authorized dosages, have a substantial influence on the results of antimicrobial consumption in pigs. To enable international comparison of veterinary antimicrobial consumption data, harmonized units of measurement, animal weights and animal (sub) categories are needed. [ABSTRACT FROM AUTHOR]

New lipid-associated formulations of amphotericin B (AmB) have been developed in order to reduce toxicity and enhance the efficacy of AmB by allowing administration of higher doses of the drug. We determined the in vivo dose-response relationships of 1 day and 7 day treatment of AmB, Ambisome (AmBi) and Abelcet (ABLC) in a non-neutropenic murine model of invasive aspergillosis by using survival as an endpoint. Female CD-1 mice were infected intravenously 48 h prior to start therapy with Aspergillus fumigatus (1×107 conidia/mouse). Groups of 10 mice were treated iv for 1 day or 7 days with increasing 2-fold doses of AmB, ABLC and AmBi up to a maximum of 20 mg/kg/day. Mortality was determined twice daily until day 15. Results were analyzed using product-moment survival analysis and by determining the dose response relationships on day 15. Survival at day 15 of mice with 7 day AmBi or ABLC treatment was significantly better than that of controls or AmB. The ED50s of AmBi and ABLC were 0.06 (95% CI: 0.03–0.127) mg/kg and 0.21 (0.06–0.66) mg/kg respectively. In addition, the maximum effect was higher for AmBi than ABLC, 90% survival versus 68%, respectively. Most of the effects of treatment with AmBi were reached after 1 day of treatment, indicating that the first dose given is most important in predicting survival. This study shows that AmBi and ABLC were significantly more efficacious than AmB in a non-neutropenic murine model of invasive aspergillosis, and that the effect observed was primarily dependent on the first dose administered. [ABSTRACT FROM AUTHOR]

Since the origin of an "‘International Collaborative Study on Antibiotic Sensitivity Testing’" in 1971, considerable advancement has been made to standardize clinical susceptibility testing procedures of antimicrobial agents. However, a consensus on the methods to be used and interpretive criteria was not reached, so the results of susceptibility testing were discrepant. Recently, the European Committee on Antimicrobial Susceptibility Testing achieved a harmonization of existing methods for susceptibility testing and now co-ordinates the process for setting breakpoints. Previously, breakpoints were set by adjusting the mean pharmacokinetic parameters derived from healthy volunteers to the susceptibilities of a population of potential pathogens expressed as the mean minimum inhibitory concentration (MIC) or MIC90%. Breakpoints derived by the deterministic approach tend to be too high, since this procedure does not take the variabilities of drug exposure and the susceptibility patterns into account. Therefore, first-step mutants or borderline susceptible bacteria may be considered as fully susceptible. As the drug exposure of such sub-populations is inadequate, resistance development will increase and eradication rates will decrease, resulting in clinical failure. The science of pharmacokinetics/pharmacodynamics integrates all possible drug exposures for standard dosage regimens and all MIC values likely to be found for the clinical isolates into the breakpoint definitions. Ideally, the data sets used originate from patients suffering from the disease to be treated. Probability density functions for both the pharmacokinetic and microbiological variables are determined, and a large number ofMIC/drug exposure scenarios are calculated. Therefore, this method is defined as the probabilistic approach. The breakpoints thus derived are lower than the ones defined deterministically, as the entire range of probable drug exposures fromlow to high is modeled. Therefore, the amplification of drugresistant sub-populations will be reduced. It has been a long journey since the first attempts in 1971 to define breakpoints. Clearly, this implies that none of the various approaches is right or wrong, and that the different approaches reflect different philosophies and mirror the tremendous progress made in the understanding of the pharmacodynamic properties of different classes of antimicrobials. [ABSTRACT FROM AUTHOR]

Ceftazidime demonstrates time-dependent killing, which is maximal at 4 x or 5 x MIC for the organism, consequently continuous infusion (CI) has been proposed to ensure adequate ceftazidime concentrations for the entire course of therapy. Severe intra-abdominal infections (IAIs) require surgical or percutaneous drainage for management, and ceftazidime is frequently prescribed. Cardiovascular or metabolic changes and renal or liver dysfunction may alter drug pharmacokinetics during severe IAIs, and no data exist on concentrations of ceftazidime reached in the peritoneal fluid. The objectives here were to determine the pharmacokinetics of ceftazidime during continuous and intermittent administration in patients with severe IAIs, and to measure the concentrations of ceftazidime in the peritoneal exudate. Eighteen surgical patients with severe IAI and a creatinine clearance of >30 mL/min were studied. A non-randomized pilot study of six patients treated with CI alone was followed by a prospective, randomized comparative study of 12 patients. Pilot study patients received ceftazidime 1 g iv followed by a 4.5 g CI over 24 h. Randomized patients received either ceftazidime continuously as above or 1.5 g tds. Samples for pharmacokinetic analyses were collected on days 2 and 4. Ceftazidime concentrations were determined by high-performance liquid chromatography. CI resulted in a mean serum concentration >40 mg/L and a T> 4 x MIC for most pathogens encountered in severe IAIs for >90% of the course of therapy in both serum and peritoneal exudate. Eight-hourly administration resulted in T> 4 x MIC for most pathogens encountered in severe IAIs for >90% of the dosing interval, but in peritoneal exudate for only 44% of the dosing interval. During CI, AUCs in the peritoneal exudate were c. 60% of the concomitant serum AUCs. In critically ill surgical patients with severe IAIs, CI of ceftazidime resulted in more favourable concentrations in serum and peritoneal exudate than 8-hourly bolus infusion. [ABSTRACT FROM AUTHOR]

Objectives: (1) To determine the pharmacokinetics of sequential intravenous and enteral fluconazole in the serum of surgical intensive care unit (ICU) patients with deep mycoses. (2) To determine the concentrations of fluconazole reached at the site of infection. (3) To determine if enteral administration of fluconazole, which has an important pharmaco-economic advantage, is justified in this specific patient group.Design: Descriptive, sequential study as a part of a therapeutic drug monitoring programme.Setting: Eighteen-bed surgical ICU in a referral centre.Patients: Fourteen critically ill surgical patients with recent gastro-intestinal (GI) surgery and deep mycosis caused by a fluconazole-susceptible fungus and a calculated creatinine clearance of more than 40 ml/min.Interventions: Fluconazole dosage regimen: 400 mg i. v. every 24 h with an extra dose of 400 mg i.v. after 12 h on day 1. If the clinical condition allowed enteral administration on day 4, the content of two capsules of 200 mg was given via the feeding tube with concomitant enteral feeds.Measurements and Main Results: Serum, exudate from the site of infection and urine samples collected at assumed steady state ( after > or = 5 doses). Fluconazole concentrations were determined by high-performance liquid chromatography (HPLC). The mean area under the concentration curve (AUC0-24 h) in serum after enteral administration did not significantly differ from the AUC0-24 h during intravenous treatment. The elimination half-life was longer compared to healthy volunteers. The mean (95% CI) estimated bioavailability was 124 (90-158)%. The mean (95% CI) area under the concentration time curves (AUCs) achieved in the exudate from the site of infection were 67 (55-79)% of the AUCs reached in serum for both regimens.Conclusions: In critically ill patients with recent GI surgery and/or peritonitis the bioavailability of enteral fluconazole was adequate. The concentrations of fluconazole reached in exudate were lower than those in serum for both regimens, but adequate to treat most cases of deep mycoses in this specific patient group. [ABSTRACT FROM AUTHOR]

During the last few decades, several carbapenems have been developed. The major characteristic of the newer drugs, such as MK-826, is a prolonged half-life. Alternatively, some carbapenems have been developed that can be given orally, such as CS-834 and L-084. Although imipenem and panipenem have to be administered with a co-drug to prevent degradation by the enzyme dehydropeptidase-1 and reduce nephrotoxicity, the newer drugs such as meropenem, biapenem and lenapenem are relatively stable towards that enzyme. Structural modifications have, besides changes in pharmacology, also led to varying antimicrobial properties. For instance, meropenem is relatively more active against Gram-negative organisms than most other carbapenems, but is slightly less active against Gram-positive organisms. Except for half-life and bioavailability, the pharmacokinetic properties of the carbapenems are relatively similar. Distribution is mainly in extracellular body-water, as observed both from the volumes of distribution and from blister studies. Some carbapenems have a better penetration in cerebrospinal fluid than others. In patients with renal dysfunction, doses have to be adjusted, and special care must be taken with imipenem/cilastatin and panipenem/betamipron to prevent accumulation of the co-drugs, as the pharmacokinetic properties of the co-drugs differ from those of the drugs themselves. However, toxicity of the co-drugs has not been shown. The carbapenems differ in proconvulsive activity. Imipenem shows relatively the highest proconvulsive activity, especially at higher concentrations. Pharmacodynamic studies have shown that the major surrogate parameter for antimicrobial efficacy is the percentage of time of the dosage interval above the minimum inhibitory concentration (MIC). The minimum percentage percentage of time above the MIC (TaM) needed for optimal effect is known in animals (30 to 50%), but not in humans. It is probably less than 100%, but may be higher than 50%. Dosage regimens currently in use result in a TaM of about 50% at 4 mg/L, which is the current 'susceptible' breakpoint determined by the National Committee for Clinical Laboratory Standards (NCCLS) for most micro-organisms. Dosage regimens in patients with reduced renal clearance should be based on the TaM. The increased half-life of the newer carbapenems will probably lead to less frequent administration, although continuous infusion may still be the optimal mode of administration for these drugs. The availability of oral carbapenems will have a profound effect on the use of carbapenems in the community. [ABSTRACT FROM AUTHOR]

The most important pharmacodynamic parameter for beta-lactam antibiotics has been shown to be the time above the MIC, which is used as an argument to administer beta-lactam antibiotics by continuous infusion. Studies in vitro and in laboratory animals comparing efficacy of continuous and intermittent infusion of beta-lactam antibiotics generally show continuous infusion to be more efficacious. While comparative trials in humans are scarce and a significant difference was only found in subgroup analysis in one study, several case-reports support the use of continuous infusion. Arguments in favour and against continuous infusion are discussed. Although dose-ranging studies have not yet been performed in humans, the results from in-vitro and in-vivo experiments indicate that 4 x MIC for the infecting bacterium would be the target concentration. Pharmacokinetic studies which have been performed in humans during continuous infusion show that serum concentrations can be predicted from total clearance or, using population pharmacokinetic modelling, the elimination rate constant as obtained during intermittent infusion. A nomogram is presented which allows calculation of the daily dose to obtain the target steady state blood concentrations suggested by the susceptibility of the infecting bacterium, usually 4 x MIC. For bacteria with a low MIC, the daily dose may be substantially lower than that used in conventional dosing regimens, while in infections which are difficult to treat as a result of more resistant bacteria, continuous infusion may be more effective than an equivalent bolus dose. [ABSTRACT FROM AUTHOR]

We investigated the emergence of resistance to 15 anti-pseudomonal antibiotics amongst Pseudomonas aeruginosa isolates from 34 chronically colonized patients with cystic fibrosis by comparing the susceptibilities of strains isolated before 1987 and after 1989 from the same patients. Strains obtained after 1989 from a further 19 patients who were newly colonized served as controls. The 34 pairs of isolates demonstrated a marked increase in resistance which could not be accounted for by a general increase in resistance during the intervening years since the susceptibility patterns of strains isolated before 1987 were similar to those of strains isolated from patients in the control group. There was a strong correlation between this increase in resistance and both the frequency of admissions to and the number of days spent in hospital. Cluster analysis of the changes in susceptibility for individual antibiotics revealed four distinct patterns of resistance: the fluoroquinolones, with the exception of ofloxacin; the aminoglycosides; the ureidopenicillins and aztreonam; and the cephalosporins, carbapenems, carboxypenicillins and ofloxacin. We conclude that the long-term administration of anti-pseudomonal antibiotics to patients who are chronically colonized with P. aeruginosa is associated with the development of resistance. [ABSTRACT FROM AUTHOR]

The pharmacokinetics and penetration into suction blister fluid of meropenem was investigated after intermittent (10 mg/kg/6 h) and during continuous infusion (10 mg/kg/6 h) in eight healthy male volunteers in a crossover fashion. Concentrations in serum, urine and blister fluid were determined by a HPLC method. The pharmacokinetic parameters in serum (±s.d.) r1/v/AUC and clearance after the third dose of intermittent infusion were 62·7 (11·4) min, 43·5 (7·1) mg.h/L and 292·1 (36·8) mL/min respectively. The penetration in blister fluid was rapid and good, with a AUC ratio blister fluid/serum of 84·7 (11·4)% During continuous infusion, from 12 to 18 h after the start of the infusion, the mean concentration in serum was 6·3 (0·7, S.D.) mg/L and in blister fluid 54 (0·7, s.d.) mg/L. The clearance was 338·3 (45·6) mL/min for scrum. Urinary recovery was 61·6 (8·7)% after intermittent and 61·9 (6·9)% after continuous infusion. [ABSTRACT FROM PUBLISHER]

The activity of quinupristin/dalfopristin was compared with that of other widely used antibiotics against 355 strains isolated from patients with endocarditis. MICs were determined by a standard agar dilution method. Quinupristin/dalfopristin was inhibitory at 1 mg/L for all coagulase-negative staphylococci (n = 36) and for the majority of Staphylococcus aureus strains (n = 87). The activity of quinupristin/dalfopristin against 186 viridans streptococci was somewhat dependent on the species, with MIC50s ranging from 0.5 to 2 mg/L, being least active against Streptococcus bovis and most active against Streptococcus gordonii and Streptococcus mitis. For the staphylococci, quinupristin/dalfopristin was as active against erythromycin-susceptible as erythromycin-resistant strains. Viridans streptococci showed a slight but significant correlation between sensitivity to erythromycin and quinupristin/dalfopristin. It is concluded that quinupristin/dalfopristin has the potential to treat serious infections such as endocarditis caused by Gram-positive cocci. [ABSTRACT FROM PUBLISHER]

Background: The objective of the study was to estimate the prevalence of gonorrhoea and chlamydial infections and to determine sexual and demographic correlates for these sexually transmitted diseases (STD) among visitors of an STD clinic.Methods: In 1994, a cross-sectional study was carried out among 2984 consecutive visitors of the STD clinic of the University Hospital Rotterdam.Results: The prevalence of chlamydial infection was 12.1% for women and 12.3% for men. For gonorrhoea, prevalence was 3.2% and 6.0%, respectively. For men, gonorrhoea was independently associated with multiple partners in the last month, homosexual activities, a history of gonorrhoea, last sexual contact in the past 4-14 days and casual partners. In contrast, chlamydial infection was less likely to be found in homosexual men and male intravenous drug users. Additionally, chlamydial infection was independently associated with young age, multiple partners in the last 6 months and with last sexual contact in the past 2 months. For women, intravenous drug use (associated with commercial sex work) and a history of trichomoniasis were independent risk factors for gonorrhoea. Independent risk factors for chlamydial infection in women were: young age, two or three sexual partners during life and last sexual contact within 2 months. Chlamydial infection was uncommon in commercial sex workers.Conclusions: The differences in the epidemiological correlates suggest that chlamydial infection is more diffusely spread into the general population than gonorrhoea. Additionally, it is hypothesized that men acquire their chlamydial infection through less stable relationships and subsequently infect their regular female partner. [ABSTRACT FROM AUTHOR]

Focuses on the use of combination chemotherapy for the treatment of invasive infections by Scedosporium prolificans. Other treatment options; Pathogenesis of the disease.

In total, 881 presumptive clinical isolates ofStreptococcus pneumoniaecollected from throughout The Netherlands were analysed to determine their mechanisms of macrolide resistance. Isolates were identified initially by participating laboratories using their own standard identification technique, followed by determination of MICs with Etests. Only 797 isolates were confirmed as pneumococci following bile-solubility tests,lytAPCR and 16S rRNA sequencing. Of these confirmed pneumococci, 59 (7.4%) isolates were macrolide-resistant. Analysis by PCR indicated that 34 (57.6%) isolates harboured only theerm(B) gene and 16 (27.1%) only themefgene. Three (5.1%) isolates carried botherm(B) andmef, while six (10.2%) isolates were negative for both mechanisms. Of the six negative isolates, three had a mutation in the 23S rRNA gene, and three were negative for all mechanisms tested. No isolates with theerm(A) subclasserm(TR) gene were detected. Among the 19mef-positive isolates, 14 (73.7%) carried themef(A) gene, and only five (26.3%) carried themef(E) gene. No linezolid cross-resistance or multiresistance (resistance to more than two classes of antibiotics) was observed. [ABSTRACT FROM AUTHOR]

Background: A renewed interest in the usage of polymyxins has been observed, as they are the only treatment option left for multidrug resistant (MDR) and pan-drug resistant (PDR) pathogens like Acinetobacter baumannii. However, knowledge of the pharmacokinetics (PK) and pharmacodynamics (PD) of polymyxins is limited, resulting in inappropriate dosing, potential toxicity and development of resistance. We planned to conduct this prospective PK-PD study of intravenously administered colistin in Indian patients with MDR Gram-negative infections to estimate the levels of both total and free colistin. Methods & Materials: This was a prospective PK-PD study of intravenously administered colistin in ten patients with MDR Gram-negative infections. The recommended systemic dose of prodrug, colistin methanesulfonate (CMS) was given as 4-6 mg/kg per day as a short-term infusion (for 1 hour) or 1-2 million IU/day in three divided doses (12,500 IU/1mg of CMS). Highly sensitive UHPLC-MS/SRM method was developed and validated to quantify free and total colistin from human sera. Correlation between the predictor variables like AUC/MIC ratio was performed using Graph- PadInstat ver. 6 for Mac version 10.10.1 (GraphPad Software, San Diego CA: www.graphpad.com). Results: The area under the plasma concentration-versus-time curve over 8 hrs (AUC0 - 8) for free and total colistin ranged after 5th dose from28.2 to 126mg*Y? h/liter and25.8 to 404.9mg*Y? h/l respectively. All the follow up blood cultures were sterile and majority of the patients survived. Conclusion: This is the first Indian study where free colistin levels were also estimated. The desired colistin levels to be effective without giving the loading dose were achieved in these Indian patients. This study challenges the pharmacokinetic rationale for a loading dose similar to a study byGregoire N, et al (2014). [ABSTRACT FROM AUTHOR]