Changes in treatment of community-onset Clostridioides difficile infection after release of updated guidelines, Atlanta, Georgia, 2018.

Updated Clostridioides difficile infection (CDI) guidelines published in 2018 recommend vancomycin as first-line treatment. Of 833 community-onset CDI cases in metropolitan Atlanta, Georgia in 2018, over half did not receive first-line treatment, although guideline adherence increased over the year. Second-line treatment was more common in patients treated in ambulatory settings.

Comparative efficacy of linezolid and vancomycin for endotracheal tube MRSA biofilms from ICU patients.

PURPOSE: To compare the efficacy of systemic treatment with linezolid (LNZ) versus vancomycin (VAN) on methicillin-resistant Staphylococcus aureus (MRSA) burden and eradication in endotracheal tube (ETT) biofilm and ETT cuff from orotracheally intubated patients with MRSA respiratory infection. METHODS: Prospective observational clinical study was carried out at four European tertiary hospitals. Plasma and endotracheal aspirate (ETA) levels of LNZ and VAN were determined 72 h after treatment initiation through high-performance liquid chromatography or bioassay. LNZ or VAN concentration in the ETT biofilm and MRSA burden and eradication was determined upon extubation. The minimum inhibitory concentration (MIC) for LNZ and VAN was assessed by E-test strips (Biomerieux®). Scanning electron microscopy images were obtained, and ETT biofilm thickness was compared between groups. RESULTS: Twenty-five patients, 15 treated with LNZ and 10 with VAN, were included in the study. LNZ presented a significantly higher concentration (µg/mL) than VAN in ETT biofilm (72.8 [1.3-127.1] vs 0.4 [0.4-1.3], p < 0.001), although both drugs achieved therapeutic plasma levels 72 h after treatment initiation. Systemic treatment with LNZ achieved lower ETT cuff MRSA burdens than systemic treatment with VAN. Indeed, LNZ increased the MRSA eradication rate in ETT cuff compared with VAN (LNZ 75%, VAN 20%, p = 0.031). CONCLUSIONS: In ICU patients with MRSA respiratory infection intubated for long periods, systemic treatment with LNZ obtains a greater beneficial effect than VAN in limiting MRSA burden in ETT cuff.

Hunter screening design to understand the product variability of solid dispersion formulation of a peptide antibiotic.

The focus of present research was to understand and control the variability of solid dispersion (SD) formulation of non-ribosomal peptide antibiotic, vancomycin (VCM). Hunter screening design was constructed using seven independent variables namely melting temperature (X1), congealing temperature (X2), mixing time (X3), type of capsule shell (X4), filling method (X5), molecular weight of polyethylene glycol (PEG, X6) and surfactant type (X7), and responses measured were cumulative percentage of VCM released in 45 min (Y1) and potency (Y2). The SD formulations were prepared by melt-fusion method, and tested for dissolution, potency, and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and near infrared chemical imaging (NIR-CI). Statistically significant (p<0.05) effect of congealing temperature (X2), type of capsule shell (X4), filling method (X5), molecular weight of PEG (X6) was revealed on Y1, and R(2) of 0.992 was obtained between experimental and predicted value. None of the factors have statistically significant (p>0.05) influence on Y2. SEM, DSC and PXRD indicated crystalline nature of SD formulations. Homogeneity of SD formulations was shown by NIR-CI images. In summary, the quality of VCM SD formulations could be assured by controlling the critical factors during manufacturing.

The effect of paraproteins and rheumatoid factor on four commercial immunoassays for vancomycin: implications for laboratorians and other health care professionals.

BACKGROUND: Paraproteins, immunoglobulins (Igs), which are elevated in various autoimmune disorders, are known to interfere with various laboratory immunoassays, including vancomycin (VANC). Rheumatoid factor (RF), a known immunoassay interferant, may cause falsely elevated results. OBJECTIVES: The aims of this study were to (1) evaluate the effect of 3 paraproteins (IgA, IgG, and IgM) on 4 commercial VANC immunoassays [fluorescence polarization immunoassay; enzyme multiplied immunoassay; 2 particle-enhanced turbidimetric inhibition immunoassays]; (2) determine the concentration at which the effect is obtained, and (3) examine the influence of RF on the VANC methods. METHOD: Serum and plasma pools from patients prescribed VANC and a spiked VANC pool (20 mg/L) were each mixed 1:1 with individual patient specimens containing IgA (6-63 g/L), IgG (6-54 g/L), IgM (3-30 g/L) (n = 4 for each Ig), and a patient RF pool (196 IU/L). The mixtures (n = 39) were split and distributed for VANC analysis. RESULTS: IgA and IgG in serum and plasma did not affect any of the VANC immunoassays. RF added to plasma specimens did not interfere, but in serum, elevated VAN results were observed. IgM did not affect the fluorescence polarization immunoassay and enzyme multiplied immunoassay methods but did attenuate VANC concentrations by both particle-enhanced turbidimetric inhibition immunoassays (Siemens, Beckman Coulter), with a more pronounced effect on the latter, producing concentrations >20% lower than expected in the patient serum and spiked plasma pools. The effect was progressively negative at effective IgM concentrations of 10 and 15 mg/L. CONCLUSIONS: This phenomenon is a major analytical and clinical issue that must be communicated to health care professionals caring for patients receiving VANC, so optimal therapy is achieved.

Determinants of early inadequate vancomycin concentrations during continuous infusion in septic patients.

Vancomycin is frequently administered to critically ill patients by continuous infusion in order to optimise drug efficacy; however, there are few data available on the efficacy of this strategy in septic patients. In this retrospective analysis, 261 patients treated with continuous infusion of vancomycin in the Department of Intensive Care at Hôpital Erasme (Brussels, Belgium) were evaluated. Creatinine clearance (CL(Cr)) was calculated from 24-h urine collection and normalised to body surface area. During the study period, 139 patients (53%) had insufficient vancomycin concentrations (<20 µg/mL) on Day 1 and 87 patients (33%) on Day 2. Patients who had insufficient drug concentrations on Day 1 of therapy were more likely to be men, to have a higher CL(Cr) and to have received lower loading and daily vancomycin doses than other patients, who received greater vasopressor support and had higher Sepsis-related Organ Failure Assessment scores. In multivariate regression analysis, high CL(Cr) and male sex independently predicted the presence of insufficient vancomycin concentrations on Days 1 and 2 of therapy. Receiver operating characteristic curve analysis for CL(Cr) showed an area under the concentration-time curve of 0.75 (95% confidence interval 0.69-0.81) to predict insufficient drug concentrations on Day 1 of therapy. A CL(Cr)>120 mL/min/1.73 m(2) had a sensitivity of 26%, a specificity of 94% and an 84% positive predictive value of 84% for vancomycin concentrations <20 µg/mL. In conclusion, approximately one-half of the septic Intensive Care Unit patients treated with continuous infusion of vancomycin at currently recommended doses had insufficient drug concentrations in the early phase of therapy. A high CL(Cr) was the variable most strongly associated with insufficient drug concentrations.

[Imprecision of vancomycin prepared for intravenous administration at the bedside in a neonatal intensive care unit]. / Étude de la variabilité dans les reconstitutions de vancomycine intraveineuse en réanimation pédiatrique.

In pediatric units, most of the intravenous medications are prepared by the attending nurse at the bedside that can be affected by an error margin, so can be imprecise. Despite the possible consequences of imprecise medications administration, published studies on the topic are scarce. The main objective of this study was to measure the difference between the prescribed vancomycine concentration and the actual concentration measured in the medication administered to the patient. The secondary objective was to determine which step in the preparation was linked to the difference in concentrations. It was a prospective study, setting in a pediatric and neonatal university hospital intensive care unit. Over a 3-month period, an aliquot from every preparation for continuous infusion of vancomycin, made at the bedside by a nurse, was collected and the modalities of the preparation noted. Vancomycin concentration was measured by high performance liquid chromatography. Sixty-four preparations, accounting for 24 patients (gestationnal age: 67 ± 75 weeks, weigh: 4.8 ± 6.5 kg) were included. Vancomycin concentrations ranged from 3.33 to 60.0mg/mL. Measured concentration were in mean 7% smaller than prescribed concentration (P<10(-3)), with a large confidence interval (75.8%-120.4% of the prescribed concentration). Imprecision the preparations was much higher than this admitted for manufactured preparation. We could not highlight any factor related to the difference in concentrations, but one third of the preparation did not respect all the ISO 7886 standards for syringes use. Bedside vancomycin preparations, like preparations for other molecules, are far more imprecise than industrial intravenous medications. Our results urge that all pediatric intravenous medications should be made only by manufacturers or pharmacists. However, it also urged clinical studies, in parallel to pharmacodynamic and pharmacokinetic studies, to make intravenous treatments as accurate as they should be.

Collaborative study for the establishment of the second international standard for vancomycin.

An international collaborative study has been organised by the European Directorate for the Quality of Medicines & HealthCare (EDQM) to establish the World Health Organization (WHO) 2nd International Standard (IS) for Vancomycin. Twelve laboratories from 10 different countries participated. The potency of the candidate material, a freeze-dried preparation, was estimated by microbiological assays with sensitive micro-organisms. As the stocks of the 1st IS for Vancomycin had been completely depleted, in order to ensure continuity between consecutive batches of the WHO IS, the European Pharmacopoeia Chemical Reference Standard (CRS) for Vancomycin batch 2 was used as a standard. It had been calibrated in a large international collaborative study against the WHO 1st IS for Vancomycin. Based on the results of the study, the 2nd IS for Vancomycin was adopted at the meeting of the WHO Expert Committee on Biological Standardisation (ECBS) in 2010 with an assigned antimicrobiological activity of 109,700 IU per vial. The 2nd IS for Vancomycin is available from the EDQM.

Resumenes de articulos de la literatura pediatrica: vancomicina en combinación con otros antimicrobianos en el tratamiento de infecciones graves por staphylococcus aureus meticilino-resistente / Abstracts of articles in the pediatric literature: vancomycin in combination with other antimicrobials in the treatment of serious infections due to methicillin-resistant staphylococcus aureus

La vancomicina frecuentemente es combinada con otros antimicrobianos debido a su deficiencia en el tratamiento de infecciones graves por Staphylococus aureus meticilino resistente (MRSA).

Stability of vancomycin in icodextrin peritoneal dialysis solution.

BACKGROUND: Icodextrin is a glucose polymer used as an alternative osmotic agent in peritoneal dialysis (PD) solutions. There are few data regarding the long-term stability of vancomycin in icodextrin PD solution. OBJECTIVE: To determine the chemical stability of vancomycin in icodextrin PD solution in polyvinyl chloride containers over a 7 day period at 4, 24, and 37 degrees C. METHODS: Study samples were prepared by adding 2000 mg vancomycin HCl to commercially available 2.0 L bags of icodextrin 7.5% PD solution. Nine bags were prepared and stored in the following conditions: 3 under refrigeration (5 degrees C), 3 at room temperature (24 degrees C), and 3 at body temperature (37 degrees C). Samples were withdrawn from each bag immediately after preparation and at predetermined intervals over the subsequent 7 days. Solutions were visually inspected for precipitation, cloudiness, or discoloration at each sampling interval. Total concentration of vancomycin in dialysate fluid was determined by high performance liquid chromatography. RESULTS: Under refrigeration, a mean +/- SD of 99.7% +/- 0.5% of the initial vancomycin concentration remained at 168 hours (7 days). At room temperature, 97.5% +/- 3.4% remained at 168 hours. At body temperature, 94.3% +/- 3.9% remained at 24 hours. Stability was not assessed beyond these time points. CONCLUSIONS: Premixed vancomycin-icodextrin PD solutions, whether stored refrigerated or at room temperature, were found to be stable for up to 7 days. However, we recommend that these solutions be kept refrigerated whenever possible. Solutions stored at body temperature were stable for up to 24 hours, permitting the practice of prewarming solutions prior to administration.

Adaptation of methicillin-resistant Staphylococcus aureus in the face of vancomycin therapy.

For the past 2 decades, vancomycin has served as the cornerstone of therapy against serious methicillin-resistant Staphylococcus aureus infections. This role is increasingly challenged by questions of efficacy, including reduced efficacy against infections caused by glycopeptide-intermediate S. aureus strains. In an evaluation of clinical glycopeptide-intermediate S. aureus isolates and serial, clinical methicillin-resistant S. aureus isolates obtained from patients receiving vancomycin for the treatment of bacteremia, we found that loss of function of the accessory gene regulator operon may confer a survival advantage to S. aureus under vancomycin selection pressure, particularly in strains with the accessory gene regulator group II genotype. Other advantages in a nosocomial setting may include enhancement of biofilm formation and promotion of physiologic changes supporting colonization. We conclude that loss of accessory gene regulator function in methicillin-resistant S. aureus might, in part, explain the decreased efficacy of vancomycin in the therapy of methicillin-resistant S. aureus bacteremia, thus highlighting the need to reevaluate the criteria of susceptibility to vancomycin.

Pharmacoeconomics: disease-based management applications.

Pharmacoeconomic information is rapidly becoming an accepted format for evaluating and comparing various treatment options. Such information may either supplement or replace standard methods for evaluating new drugs for possible inclusion on the formulary. It is important to recognize the pitfalls that may accompany different methods of collecting and evaluating pharmacoeconomic studies. Such information is important because drug use and outcomes in a real-world setting may differ substantially from those within the confines of a clinical trial setting.

An improved micromethod for vancomycin determination by high-performance liquid chromatography.

A micromethod using reversed-phase high-performance liquid chromatography for the analysis of vancomycin in human serum or plasma was developed. Ristocetin was used as the internal standard. Chromatographic conditions included an amino propyl column, a mobile phase with 62% acetonitrile and 38% sodium phosphate buffer (pH 7.0), a total run time of 10 min, and ultraviolet absorbance detection at 225 nm. Multilevel calibration was found to be linear between 1.0 and 100 micrograms/ml with correlation coefficients of the calibration line slope consistently > 0.999. Recovery of vancomycin from serum was nearly complete, and no interference from commonly used drugs was observed. This procedure is simple, sensitive, rapid, precise, selective, and requires only 50 microliters of serum or plasma for completion.

Chemical peritonitis secondary to intraperitoneal vancomycin.

Although previously reported in the literature, the existence of chemical peritonitis due to vancomycin in patients on peritoneal dialysis remains controversial. We report four similar episodes of sterile peritonitis in three patients receiving intraperitoneal (IP) vancomycin. The prior report implicated a change in the brand of vancomycin preparation, from Vancocin to Vancoled, as a contributing factor. We noted the occurrence of such episodes following a switch from Vancocin to a generic preparation from Abbott Laboratories. High-performance liquid chromatographic (HPLC) profiles of the three preparations show Vancocin to have a lower level of impurities than the other two; the presence of certain contaminants in the other brands may be contributing to the clinical difference observed. We conclude that chemical peritonitis due to IP vancomycin administration does occur, and that increased awareness of this entity could allow other cases to be identified.

Clinical performance of the EMIT vancomycin assay.

In evaluating the EMIT system for vancomycin used in the Cobas Bio centrifugal analyzer, we found two potential problems, each of which may have important clinical ramifications. First, precision, though acceptable in concentrations up to 30 mg/L, was marginal in the range above 30 mg/L. Second, when EMIT values were compared with those by fluorescent polarization immunoassay (TDx), we found a good correlation but a significant proportional bias: [EMIT] = (0.877)[TDx] + 0.435 mg/L (r = 0.971). The proportional bias was much more pronounced in specimens with high creatinine values than in specimens with normal values for creatinine. It remains to be determined which method is more nearly accurate. This imprecision and proportional bias in specimens with increased creatinines lead us to conclude that the EMIT vancomycin system should be used with caution.

International standards and international reference preparations: amphotericin B, vancomycin, capreomycin, cefalotin, demethylchlortetracycline, gentamycin, gramicidin S, kanamycin and kanamycin B, lincomycin, lymecycline, methacycline, paromomycin, rifamycin SV, ristocetin and ristocetin B, spiramycin, and triacetyloleandomycin.

Each of the preparations described here was obtained and evaluated at the request of a WHO Expert Committee on Biological Standardization. Unless otherwise stated, a standard procedure was used to distribute the material into individual ampoules. The procedure was as follows. Upon receipt by the National Institute for Medical Research (NIMR), London, materials were stored temporarily in the dark at a temperature of -10 degrees C or lower, and protected from moisture. At a convenient time they were brought back to room temperature, mixed, and distributed into individual neutral glass ampoules so that each ampoule contained 50-100 mg of powder. If it was known that the material was light-sensitive non-actinic glass ampoules were used. After exhaustive drying in vacuum over phosphorus(V) oxide, the ampoules were either constricted (up to 1963) or fitted with capillary leak plugs, dried for a further period under the same conditions, filled with dry nitrogen, and sealed by fusion of the glass. The total drying period varied from 8 to 38 days according to the nature of the material. After they had been tested for leaks, the ampoules were stored in the dark at -20 degrees C.