Liquid chromatography-tandem mass spectrometry methods for quantification of total and free antibiotic concentrations in serum and exudate from patients with post-sternotomy deep sternal wound infection receiving negative pressure wound therapy.

BACKGROUND: Systemically administered antibiotics are thought to penetrate the wounds more effectively during negative pressure wound therapy (NPWT).To test this hypothesis total and free antibiotic concentrations were quantified in serum and wound exudate. METHODS: UHPLC-MS/MS methods were developed and validated for the determination of ceftazidime, cefepime, cefotaxime, cefuroxime, cefazolin, meropenem, oxacillin, piperacillin with tazobactam, clindamycin, ciprofloxacin, sulfamethoxazole/trimethoprim (cotrimoxazole), gentamicin, vancomycin, and linezolid. The unbound antibiotic fraction was obtained by ultrafiltration using a Millipore Microcon-30kda Centrifugal Filter Unit. Analysis was performed on a 1.7-µm Acquity UPLC BEH C18 2.1 × 100-mm column with a gradient elution. RESULTS: The validation was performed for serum, exudates and free fractions. For all matrices, requirements were met regarding linearity, precision, accuracy, limit of quantitation, and matrix effect. The coefficient of variation was in the range of 1.2-13.6%.and the recovery 87.6-115.6%, respectively. Among the 29 applications of antibiotics thus far, including vancomycin, clindamycin, ciprofloxacin, oxacillin, cefepime, cefotaxime, cotrimoxazole, and gentamicin, total and free antibiotic concentrations in serum and exudate were correlated. CONCLUSION: This method can accurately quantify the total and free concentrations of 16 antibiotics. Comparison of concentration ratios between serum and exudates allows for monitoring individual antibiotics' penetration capacity in patients receiving NPWT.

Therapeutic drug monitoring guided fluconazole therapy in a patient with cholangitis sepsis.

Candida and other fungal species play an increasing role in nosocomial infections, including cholangitis and cholangiosepsis. Early diagnosis and prompt treatment are essential in successful patient outcomes. Fluconazole is an antifungal of choice in fluconazole-sensitive Candida infections. Little information is known about the fluconazole biliary excretion. Decreased tissue penetration may be one of the possible causes of treatment failure. Due to favorable pharmacokinetics, therapeutic drug monitoring of this antifungal has not been recommended routinely. In the presented case we report the successful therapeutic drug monitoring-guided fluconazole treatment in a patient with cholangitis and cholangiosepsis caused by fluconazole-sensitive Candida spp.

Lay abstract A successful fluconazole treatment of Candida cholangitis based on therapeutic drug monitoring, is described in our case study. Unlike other azole antimycotic agents, fluconazole is not considered a desirable candidate for therapeutic drug monitoring. However, as shown in our case study, a fixed dosage regimen might not lead to adequate fluconazole exposure in every patient and a personalized dosing regimen might be useful in the achievement of adequate fluconazole exposure and the successful treatment of Candida infection.

Therapeutic monitoring of amiodarone: pharmacokinetics and evaluation of the relationship between effect and dose/concentration.

Amiodarone is the most effective agent in the therapy of arrhythmias. However, the clinical effect of acute and chronic treatment is unclear and there are differences irrespective of comparable plasma/myocardial amiodarone and its metabolite desethylamiodarone concentations as well. Its unusual pharmacokinetics results in interindividual variation in plasma levels. The association between amiodarone and desethylamiodarone plasma levels and clinical efficacy is difficult to evaluate. This review was carried out to assess whether there is any objective correlation between amiodarone and desethylamiodarone plasma levels and the clinical effect. We summarized the results of relevant studies and clarified the relationship between plasma levels and effect vis á vis the pharmacokinetics and pharmacogenetics of this drug. Certain correlation was seen with oral amiodarone therapy, in others, plasma amiodarone levels were unrelated to therapeutic response and showed no correlation with changes in electrocardiogram or electrophysiological parametres. Several studies show that plasma concentration ranging between 0.5 and 2.5 mg/L appears to be the most effective, others demonstrate no difference between responders and non-responders. One way of interpreting plasma levels is to establish an individual patient´s effective concentration. Therapeutic drug monitoring can contribute to determining optimal concentration.

Vancomycin pharmacokinetics during high-volume continuous venovenous hemofiltration in critically ill septic patients.

AIMS: To assess the influence of continuous venovenous hemofiltration (CVVH) at a filtration rate of 45 mL/kg/h on vancomycin pharmacokinetics in critically ill septic patients with acute kidney injury (AKI). METHODS: Seventeen adult septic patients with acute kidney injury treated with CVVH and vancomycin were included. All patients received first dose of 1.0 g intravenously followed by 1.0 g/12 h if not adjusted. In sixteen patients vancomycin was introduced on the day of the start of CRRT therapy. Blood samples and ultrafiltrates were obtained before and 0.5, 1, 6 and 12 h after vancomycin administration. RESULTS: On the first day, the median total vancomycin clearance (Cltot) was 0.89 mL/min/kg (range 0.31 - 2.16). CRRT clearance accounted for around 50-60% of the total clearance of vancomycin found in a population with normal renal function (0.97 mL/min/kg). Vancomycin serum concentrations after the first dose were below the required target of 10 mg/L as early as 6 h in 10 patients, AUC0-24/MIC ≥ 400 ratio was achieved in 10 patients on the first day. CONCLUSIONS: CVVH at a filtration rate of 45 mL/kg/h leads to high and rapid extracorporeal removal of vancomycin in critically ill patients. Due to the rapid change in patient clinical status it was impossible to predict a fixed dosage regimen. We recommend blood sampling as early as 6 h after first vancomycin dose with maintenance dose based on vancomycin serum level monitoring.

Vancomycin removal during low-flux and high-flux extended daily hemodialysis in critically ill septic patients.

AIMS: To determine the extent of vancomycin removal and vancomycin pharmacokinetics in septic patients with AKI using daily hemodialysis with polysulphone high-flux and low-flux membrane. METHODS: Five patients received 6 h daily dialysis with low-flux polysulphone membrane, four patients with high-flux polysulphone membrane. Vancomycin was administered over the last hour of dialysis. The maintenance dose was adjusted based on pre-hemodialysis serum concentrations. Patients were followed up for two days. RESULTS: Median percentage of vancomycin removal by low-flux membrane dialysis was 17% (8-38%) and by high-flux membrane dialysis was 31% (13-43%). Vancomycin clearance was only moderately higher in high-flux membrane dialysis (median 3.01 L/h, range 2.34-3.5 L/h) compared to low-flux dialysis (median 2.48 L/h, range 0.53-5.68 L/h) in the first day of the study. About two-fold higher vancomycin clearance in high-flux dialysis (median 3.62 L/h, range 1.37-5.07 L/h) was observed on the second day of the study than low-flux dialysis (median 1.74 L/h, range 0.75-30.94 L/h). CONCLUSIONS: Both high-flux and low-flux membrane dialysis remove considerable amounts of vancomycin in critically ill septic patients with AKI. Application of vancomycin after each dialysis was required to maintain therapeutic concentrations.

Gentamicin pharmacokinetics during continuous venovenous hemofiltration in critically ill septic patients.

OBJECTIVE: Current dosing recommendations for administration of gentamicin to septic patients with acute kidney injury (AKI) on continuous venovenous hemofiltration (CVVH) at a filtration rate of 45 ml/kg/h are missing. AIM: To describe gentamicin pharmacokinetics and to find an optimal dosing regimen in patients on CVVH. METHODS: Seven adult patients were included. Patients received loading dose of 240 mg followed by application of maintenance dose every 24 hours. Maintenance dose was adjusted according to gentamicin C(max)/MIC ratio and drug levels simulation using a pharmacokinetic programme. RESULTS: Median total clearance (0.59-0.79 ml/min/kg) was similar to patients with normal renal function; median volume of distribution was higher than observed in non-septic patients (about 0.5 l/kg versus 0.25 l/kg). Patients with diuresis required an increase of gentamicin dose to reach C(max)/MIC ratio. CONCLUSION: Septic patients with AKI on CVVH (45 ml/kg/h) require a loading dose of 240 mg, followed by therapeutic drug monitoring to optimize maintenance dose.

[Clinical significance of cytochrome P450 genetic polymorphism--part I. Enzymatic system of cytochrome P450 and cytochrome P450 1A2]. / Význam genetického polymorfizmu enzýmov cytochrómu P450--cast I. Enzýmový systém cytochrómu P450 a cytochróm P450 1A2.

Inter-individual variability in drug response is a major clinical problem. Much of the variability has been observed in drug metabolism, particularly in the enzymes of cytochrome P450. Genetic polymorphism in these enzymes may influence a patient's response to commonly prescribed drugs. The first part of this review describes the enzymatic system of cytochrome P450 and further focuses on the influence of genetic polymorphism of cytochrome P450 1A2 on drug effect.

[Clinical significance of cytochrome P450 genetic polymorphism--part IV. Cytochrome P450 3A4 and 3A5]. / Význam genetického polymorfizmu enzýmov cytochrómu P450--cast' IV. Cytochróm P450 3A4 a 3A5.

The enzymes of cytochrome P450 3A subfamily are responsible for the metabolism of about 50% of commonly used drugs. High inter-individual variability in the activities of these enzymes has been described. The last fourth part of this review focuses on the influence of genetic polymorphism of CYP3A4 and CYP3A5 enzymes on drug effect.

Screening of binding activity of Streptococcus pneumoniae, Streptococcus agalactiae and Streptococcus suis to berries and juices.

Antiadhesion therapy is a promising approach to the fight against pathogens. Antibiotic resistance and the lack of effective vaccines have increased the search for new methods to prevent infectious diseases. Previous studies have shown the antiadhesion activity of juice from cultivated cranberries (Vaccinium macrocarpon Ait.) against bacteria, especially E. coli. In this study, the binding of two streptococcal strains, Streptococcus pneumoniae and Streptococcus agalactiae, to molecular size fractions (FI, FII and FIII, <10 kDa, 10-100 kDa, and >100 kDa, respectively) of berries and berry and fruit juices from 12 plant species were studied using a microtiter well assay. For Streptococcus suis a hemagglutination inhibition assay was used. In general, binding activity was detected especially to wild cranberry (Vaccinium oxycoccos L.) and to other Vaccinium species. S. pneumoniae cells bound most to cranberry juice fraction FI and S. agalactiae cells to cranberry fraction FIII. Hemagglutination induced by S. suis was most effectively inhibited by cranberry fraction FII. NMR spectra of some characteristic active and non-active fractions were also measured. They indicate that fractions FII and FIII contained proanthocyanidins and/or other phenolic compounds. The results suggest Vaccinium berries as possible sources of antiadhesives against bacterial infections.

Binding of Neisseria meningitidis pili to berry polyphenolic fractions.

Blocking bacterial adhesion to host surfaces provides novel potential to control infections. The present study was directed to binding and inhibitory activity of different fresh berries and berry and fruit juices against Neisseria meningitidis . Berries and juices were fractionated according to their molecular size into three fractions. A microtiter well assay for binding of N. meningitidis pili to berry and juice fractions was constructed. In addition, adhesion inhibition to human epithelial cells (HEC-1B) was tested. The active fractions were then subfractionated by employing solid-phase extraction. Subfractions were characterized by RP-HPLC-DAD, and the pili binding was evaluated by using microtiter well binding assay. Binding and inhibitory activity were detected to bilberry, cranberry, lingonberry, and crowberry fractions, which contained anthocyanins or a mixture of proanthocyanidins and flavonols. Thus, the findings identify several previously unknown binding and inhibitory activities and may suggest Vaccinium berries and crowberry as promising sources against meningococcal adherence.