Penetration of vancomycin into mediastinal and cardiac tissues in humans.

Vancomycin penetration into heart tissues (valves, myocardium, auricles, and pericardium) and mediastinal tissues (fat and sternal bone) was evaluated after two regimens of vancomycin administration. Ten patients were given 15 mg of vancomycin per kg of body weight before anesthesia. Ten other patients received the same dose and then a second 7.5-mg/kg dose at the time of initiation of cardiopulmonary bypass. Similar and satisfactory vancomycin tissue penetrations were observed in both groups. However, for some patients in the two groups, vancomycin levels in tissue were less than the MICs for potential pathogens (Staphylococcus aureus and Staphylococcus epidermidis).     

Vancomycin concentrations in infected and noninfected human bone.

Concentrations of vancomycin in bones of 14 patients undergoing total hip arthroplasty (group 1) and 5 patients with osteomyelitis (group 2) were studied. Group 1 received vancomycin, 15 mg/kg intravenously, 1 h prior to anesthesia. Group 2 received doses adjusted to achieve peak levels in serum of 20 to 30 micrograms/ml and trough levels of less than 12 micrograms/ml; bone specimens were collected during surgical debridement. The specimens were pulverized and eluted into phosphate buffer, and the supernatants were analyzed for vancomycin content by fluorescence polarization immunoassay. In group 1, vancomycin was detectable in all cancellous specimens with a mean concentration of 2.3 +/- 4.0 micrograms/g (range, 0.5 to 16 micrograms/g); 10 of 14 cortical specimens had detectable vancomycin; the mean cortical concentration was 1.1 +/- 0.8 micrograms/g (range, not detectable to 2.6 micrograms/g). In group 2, vancomycin was detectable in only two of five cortical bone specimens (mean concentration, 5.9 +/- 3.5 micrograms/g). Cancellous bone was obtained in one patient; the vancomycin concentration was 3.6 micrograms/g. In most patients the vancomycin levels in bones were higher than the MIC for susceptible staphylococci following single prophylactic doses. In the few infected patients studied, penetration was variable and deserves further study.     

Comparative evaluation of tigecycline and vancomycin, with and without rifampicin, in the treatment of methicillin-resistant Staphylococcus aureus experimental osteomyelitis in a rabbit model

OBJECTIVES: Staphylococcus aureus is the most common organism isolated in osteomyelitis. Methicillin-resistant S. aureus (MRSA) infections are particularly difficult to treat. We evaluated the efficacy of tigecycline and vancomycin with and without rifampicin in a rabbit model of MRSA osteomyelitis. METHODS: A 28 day antibiotic therapy with a subcutaneous injection of tigecycline (14 mg/kg twice daily), with and without oral rifampicin (40 mg/kg twice daily); or subcutaneous administration of vancomycin (30 mg/kg twice daily), with and without oral rifampicin (40 mg/kg twice daily) were compared. Osteomyelitis was induced with an intramedullary injection of 10(6) colony-forming units of MRSA. Infected rabbits were randomly divided into six groups: tigecycline, tigecycline with oral rifampicin, vancomycin, vancomycin with oral rifampicin, and no treatment control and tigecycline bone penetration groups. Treatment began 2 weeks after infection. After 4 weeks of therapy, the rabbits were left untreated for 2 weeks. Rabbits were then euthanized, and the tibias were harvested. The bones were cultured, and bacterial counts of MRSA were performed. RESULTS: Rabbits that received tigecycline and oral rifampicin therapy (n=14) showed a 100% infection clearance. Rabbits treated with tigecycline (n=10) showed a 90% clearance. Rabbits treated with vancomycin and oral rifampicin (n=10) also showed a 90% clearance. Rabbits treated with vancomycin (n=11) showed an 81.8% clearance. Untreated controls (n=15) demonstrated only a 26% clearance. For the tigecycline bone penetration group, the bone concentrations of tigecycline in the infected tibia were significantly higher than the non-infected ones. CONCLUSIONS: Tigecycline may be an effective alternative to vancomycin in the treatment of MRSA osteomyelitis.     

Comparative evaluation of daptomycin (LY146032) and vancomycin in the treatment of experimental methicillin-resistant Staphylococcus aureus osteomyelitis in rabbits.

A rabbit model for methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis was used to compare treatment with daptomycin, a new peptolide, and vancomycin. Daptomycin (4 mg/kg) and vancomycin (40 mg/kg) were injected subcutaneously every 12 and 6 h, respectively. After treatment, MRSA was found in bone cultures from 18 of 18 control rabbits, 10 of 17 animals treated with daptomycin, and 11 of 18 animals treated with vancomycin. Drug concentrations were measured in serum, uninfected bone, and infected bone 1 h after daptomycin or vancomycin was injected in a group of rabbits that had been infected for 3 to 4 weeks. Vancomycin was present at the highest concentrations in infected and uninfected bone. The results of this study suggest that daptomycin was similar to vancomycin in the eradication of MRSA from infected bone in an experimental model of osteomyelitis.     

High dose vancomycin for osteomyelitis: continuous vs. intermittent infusion

OBJECTIVES: To compare the efficacy, ease of use and safety of intermittent vancomycin infusion (IVI) and continuous vancomycin infusion (CVI) in high-dose therapy of osteomyelitis. Methods: Forty-four patients with an osteomyelitis requiring vancomycin for more than 4 weeks were prospectively included, 21 receiving IVI and 23, CVI. The target serum concentration of vancomycin was 20-25 mg/L. Pharmacokinetics, adverse effects, and clinical efficacy were recorded. RESULTS: The mean daily vancomycin dosing was the same in the two groups, but the serum vancomycin concentrations (trough or plateau) were lower in the IVI group than the CVI group (21.7 +/- 9.3 and 26.0 +/- 6.1 mg/L, respectively; P < 0.0001). The target concentrations were achieved quicker with CVI, and daily dosing was changed more frequently in the IVI group. After reaching the target, variability of vancomycin serum concentration (trough or plateau concentrations) was higher in the IVI group than in CVI group (standard deviation 7.9 mg/L vs. 5.6 mg/L, respectively; P = 0.001). CVI did not show clinical superiority, but adverse drug effects were more frequent in the IVI group as compared with the CVI group, 9 (42.9%) and 2 (8.7%), respectively (P = 0.03). Survival multiple regression using Cox's proportional hazard model showed that IVI (RR = 5.9, P = 0.03) and osteomyelitis of the foot (RR = 5.2, P = 0.01) were the only factors associated with adverse drug reactions leading to treatment termination. CONCLUSIONS: CVI is practical and effective, and may be a good alternative for patients requiring prolonged treatment with high vancomycin serum levels.     

The characteristics and impact indicator of vancomycin pharmacokinetics in cancer patients complicated with severe pneumonia

ObjectiveThis study was designed to investigate the characteristics and impact indicator of vancomycin pharmacokinetics in cancer patients complicated with severe pneumonia.MethodsFifty-seven cancer patients complicated with severe pneumonia were included in this research. Vancomycin serum trough concentrations were measured using the fluorescence polarization immunoassay (FPIA) method. The Bayesian estimator was used to calculate the pharmacokinetic parameters.ResultsThe average initial therapeutic dose of vancomycin was 15.18 ± 3.29 mg/kg (q12 h). Our study shows that vancomycin initial trough concentrations measured in cancer patients are significantly reduced (6.54 ± 3.11 mg/L; p < 0.0001) compared with the recommended standard vancomycin trough concentration (10–15 or 15–20 mg/L). Meanwhile, the clearance (CL) and volume of distribution (Vd) of vancomycin was increased significantly in cancer patients. Multivariate linear regression analysis revealed that Cys-C was the most important variable for vancomycin trough concentration (r² = 0.439). The relationships between vancomycin trough concentrations and Cys-C were further evaluated after the 57 patients were grouped by cut-off point (1.44 mg/L) of the serum Cys- C levels before vancomycin was administered. Compared with group Early group (Cys-C>1.44 mg/L), Delayed group (Cys-C≤1.44 mg/L) had much lower trough concentrations. Meanwhile, CL and CLcr were significantly increased in Delayed group (Cys-C≤1.44 mg/L). Although the clinical outcomes were similar between two groups, the duration of vasoactive agent in Early group was considerably shorter compared with Delayed group (χ² = 4.213; p < 0.05).ConclusionsThe serum trough concentration of vancomycin was significantly reduced in cancer patients complicated with severe pneumonia. Higher dosage regimen is needed to ensure clinical effectiveness. The Cys-C level measured prior to administration of vancomycin is suggested to be the most suitable parameter to predict whether vancomycin trough concentration is up to standard dosage. Especially for patients with baseline Cys-c less than 1.44 mg/L, it is more likely to need higher dosage algorithm.     

Concentrations of vancomycin in bone and serum of normal rabbits and those with osteomyelitis.

The concentrations of vancomycin in the bone and serum of rabbits with Staphylococcus aureus osteomyelitis were assessed after each rabbit was given a single dose of vancomycin. Simultaneous mean concentrations of vancomycin in infected rabbits 1 h after administration of the antibiotic were 36.4 +/- 4.6 micrograms/ml (serum), 5.3 +/- 0.8 microgram/g (infected bone), and 3.0 +/- 0.2 micrograms/g (noninfected bone). Concentrations of vancomycin in serum of normal controls were higher than concentrations of vancomycin in serum of osteomyelitic rabbits after 1, 2, 3, and 6 h.     

Effects of intravitreal dexamethasone on concentration of intravitreal vancomycin in experimental methicillin-resistant Staphylococcus epidermidis endophthalmitis.

Intravitreal corticosteroids in the treatment of bacterial endophthalmitis remain controversial. We utilized an experimental rabbit model of methicillin-resistant Staphylococcus epidermidis endophthalmitis (i) to calculate the intravitreal vancomycin concentration in rabbit eyes receiving intravitreal vancomycin alone or in combination with intravitreal dexamethasone and (ii) to determine whether an intravitreal steroid has any effect on intravitreal vancomycin levels. All right eyes were infected and all left eyes were uninfected. The rabbits were divided into two treatment groups: (i) 32 eyes (group I) were injected with intravitreal vancomycin, 1.0 mg (0.1 ml); (ii) 32 additional eyes (group II) were injected with intravitreal dexamethasone, 400 micrograms (0.1 ml), in addition to vancomycin. Measurement of intravitreal vancomycin concentration was performed following sacrifice, utilizing a microbiologic agar diffusion assay. Analyses of intravitreal vancomycin concentrations were performed by using model-independent parameters, with area under the concentration-time curves derived by trapezoidal approximation. The intravitreal vancomycin concentration was significantly lower in both uninfected and infected group II eyes (P less than 0.002). Analysis of intravitreal vancomycin concentration-time relationships was performed by using a nonlinear least-squares regression program; data best fit a one-compartment model. In addition, no vancomycin-dexamethasone interaction could be demonstrated. The reduced level of intravitreal vancomycin in the presence of intravitreal dexamethasone may have important clinical implications.     

Teicoplanin in cardiac surgery: intraoperative pharmacokinetics and concentrations in cardiac and mediastinal tissues.

The concentrations of teicoplanin in the sera and mediastinal and heart tissues of 23 patients undergoing cardiac surgery were measured after two regimens of teicoplanin administration. Intraoperative pharmacokinetic parameters were also obtained. Patients were randomized into two groups. Those in group 1 were given teicoplanin at 6 mg x kg(-1) intravenously at the time of induction of anesthesia. Patients in group 2 were given teicoplanin at 12 mg x kg(-1) during the same period. The maximum concentration in serum (71 +/- 20 and 131 +/- 44 mg x l(-1)), the minimum concentration in serum (3.6 +/- 1.3 and 6.8 +/- 2.1 mg x l(-1)), the area under the concentration-time curve (AUC) from 0 to 12 h (108 +/- 20 and 217 +/- 38 microg x h x ml(-1)), and the AUC from 0 h to infinity (154 +/- 36 and 292 +/- 77 microg x h x ml(-1)) were twice as high after 12-mg x kg(-1) injections as after 6-mg x kg(-1) injections. No differences in mean residence time (9.7 +/- 4.9 and 8.4 +/- 2.7 h) or terminal half-life (8.5 +/- 3.8 and 7.5 +/- 2.3 h) were observed. Teicoplanin penetrated mediastinal and heart tissues but not sternal bone, where the antibiotic was detectable in only 1 of 13 patients in group 1 and 2 of 10 patients in group 2. In group 1, 7 of 13 patients had teicoplanin concentrations in tissue that were lower than the MIC for 90% of the strains of potential pathogens tested (MIC90) that cause infection after cardiac surgery. All of the patients in group 2 but one had teicoplanin concentrations in tissue (other than in sternal bone) far in excess of the MIC90 for the potential pathogens. In conclusion, the 12-mg x kg(-1) regimen of teicoplanin is followed by a significant increase in teicoplanin concentrations in heart and mediastinal tissues and should be preferred to the 6-mg x kg(-1) regimen if teicoplanin is selected for antimicrobial prophylaxis in open heart surgery.     

Effects of prolonged vancomycin administration on methicillin-resistant Staphylococcus aureus (MRSA) in a patient with recurrent bacteraemia

OBJECTIVES: To evaluate microbiological properties of methicillin-resistant Staphylococcus aureus (MRSA) during prolonged vancomycin therapy. METHODS: We evaluated vancomycin susceptibility and heteroresistance, accessory gene regulator (agr) function, autolysis, biofilm production and in vitro vancomycin killing in serial MRSA bloodstream isolates obtained over a 30 month period from a patient with a chronic endovascular infection. RESULTS: Despite the fact that the MRSA in this patient had the same genetic background as other clinical glycopeptide intermediate-resistant S. aureus (GISA) isolates, vancomycin administered for 9 months, maintaining serum concentrations >10 mg/L, did not select for GISA. Minimal changes in vancomycin susceptibility were detected using agar dilution and population analysis methods. We noted increases in delta haemolysin production, autolysis and the bactericidal effects of vancomycin in vitro against the MRSA obtained after prolonged vancomycin suppressive therapy was discontinued. CONCLUSIONS: Despite the lack of development of detectable resistance, MRSA exposed to vancomycin for prolonged periods may begin to develop vancomycin tolerance and decreased autolysis. In addition, suppression of agr function appears to end after vancomycin is stopped. Whether these changes are prerequisites for attenuated vancomycin efficacy and the development of glycopeptide resistance warrants further study. The development of vancomycin resistance may be more difficult under conditions where vancomycin serum concentrations are maintained >10 mg/L.     

Diagnostic values of sonography for assessment of sternal fractures compared with conventional radiography and bone scans.

OBJECTIVE: This study was prospectively undertaken to evaluate the diagnostic value of sonography for detection of sternal fractures. We compared sonographic, conventional radiographic, and bone scan examinations of sternal fractures. METHODS: Fifty consecutive patients (26 male and 24 female; mean age, 45.2 years) were evaluated. Conventional radiography and sonography were performed in all patients, and bone scans were performed in 39 patients. All patients had acute pain and tenderness in anterior midline chest areas. Sonography was performed by 2 musculoskeletal radiologists within 1 to 2 days after admission. Patients underwent conventional radiography at admission and bone scans within 4 to 7 days after admission. Two radiologists reviewed all imaging findings by means of consensus. In addition, sonography was performed in 20 asymptomatic patients in a normal control group. RESULTS: Conventional radiography depicted sternal fractures in 12 of 50 patients. Sternal fractures were detected in 31 of 50 patients on sonography. Fractures on sonography were located in the manubrium (8 cases), upper sternal body (11 cases), mid sternal body (5 cases), and lower sternal body (7 cases). Bone scans showed sternal hot uptakes (accumulations of the radionuclide used) in 18 of 39 patients. In the control group, there were no bony defects or abnormal contours. CONCLUSIONS: We could detect sternal fractures more effectively with sonography than with conventional radiography and bone scans. In addition, sternal fracture locations showed relatively even distributions, and focal fractures in the manubrium were not easily detected on bone scans.     

胸骨结扎带在胸腺肿瘤胸骨劈开手术中的临床应用

目的:探讨关胸时使用胸骨结扎带在胸腺肿瘤胸骨劈开手术中的安全性和应用价值。方法:选取2020年6月至2020年12月在复旦大学附属中山医院胸外科行胸骨劈开手术的胸腺肿瘤患者34例,根据关胸时固定胸骨的材料,分为胸骨结扎带组(n=13)和钢丝组(n=21)。比较2组的固定胸骨时间、胸骨固定过程中出血量、术后疼痛视觉模拟评分、切口并发症等临床指标。结果:胸骨结扎带组的胸骨固定时间和胸骨固定过程中出血量明显少于钢丝组[(7.6±2.3)min vs(17.2±1.9) min,(44.0±34.0) mL vs(110.0±36.0) mL],胸骨结扎带组的术后疼痛视觉模拟评分明显低于钢丝组[(2.1±1.0)分vs(4.9±1.0)分],差异均有统计学意义(P0.05)。结论:胸骨结扎带在胸腺肿瘤胸骨劈开术中对胸骨的固定可靠、安全、操作简单,并可显著缩短关胸时间,减少胸骨固定过程中出血,减轻术后疼痛。     

微透析活体采样比较静脉和玻璃体内注射万古霉素在兔玻璃体内的通透性

背景：目前眼部药代动力学研究的人体及动物实验采样方法,均是在体外进行,存在诸多的弊端。目的：利用微透析活体采样技术,建立眼后节清醒动物药代动力学模型,比较静脉注射和玻璃体内注射万古霉素在兔玻璃体内的通透性。方法：纳入15只兔,制备眼内炎模型。将微透析探针植入清醒兔眼玻璃体内24h后,随机分成3组,即静脉注射组、玻璃体内注射组及静脉注射＋玻璃体内注射组,分别根据不同的给药方式注射万古霉素。高效液相色谱-紫外检测法连续检测兔眼玻璃体万古霉素的浓度,3p97药代动力学软件拟合药动学参数。结果与结论：静脉注射组兔眼玻璃体内的药物浓度较低,达不到有效的治疗效果;玻璃体内注射组及静脉注射＋玻璃体内注射组兔眼给药后72h,玻璃体内万古霉素的浓度均高于有效治疗浓度。提示微透析方法联合高效液相色谱-紫外检测法,可以连续、在线、活体检测清醒动物玻璃体内药物浓度;单次静脉注射万古霉素后,玻璃体内不能达到有效治疗剂量。     

Trough-guided Versus AUC/MIC-Guided Vancomycin Monitoring: A Cost Analysis

PurposeRecent vancomycin dosing and monitoring guidelines recommend monitoring vancomycin area under the 24-hour time–concentration curve instead of traditional trough-only monitoring. This study aimed to compare the total costs of vancomycin dosing and monitoring between trough-guided and AUC-guided approaches in a quaternary hospital from Brazil.MethodsIn this retrospective cohort study, patients were divided into 2 groups according to the monitoring method. Patients with previous renal impairment were excluded. Vancomycin AUC was estimated by using 2 steady-state serum concentrations and first-order kinetics equations. The primary outcome was total cost of vancomycin therapy and monitoring from the hospital perspective, which included costs of cumulative doses, laboratory fees, materials used in blood collection, nursing time for collection, and pharmacist time for result interpretation.FindingsA total of 68 patients were included in the AUC/MIC–guided monitoring group, and 76 patients were included in the trough-guided monitoring group. There were no significant differences between groups regarding baseline serum creatinine level, duration of vancomycin therapy, and cumulative vancomycin dose. The median (interquartile range) total vancomycin drug and monitoring cost was $298.32 ($153.81–$429.85) for the AUC/MIC–guided group compared with $285.59 ($198.81–$435.57) for the trough-guided group (P = 0.9658).ImplicationsVancomycin AUC estimation using 2 steady-state serum concentrations and first-order kinetics equations is a feasible alternative for limited-resource institutions that intend to transition from a trough approach to AUC/MIC–guided monitoring.     

Continuous intravenous administration of vancomycin in medical intensive care unit patients

Purpose

The aim of this study was to evaluate continuous vancomycin infusion (contV) in intensive care unit patients.

Materials and Methods

A retrospective study in 164 patients treated with contV was conducted. They were compared with 75 patients treated with intermittent vancomycin infusion.

Results

The median duration of vancomycin therapy in the contV group was 6 (5%-95% percentile range, 2-21) days. The median daily vancomycin dose in the contV group was 960 (526-1723) mg, resulting in a median serum vancomycin plateau concentration of 19.8 (9.8-29.4) mg/L (target: 15-25 mg/L). The contV administration regime was sufficient regarding achievement of the target serum vancomycin concentration. However, in the contV group, serum vancomycin levels were frequently in a subtherapeutic range on treatment days 1 (44%), 2 (29%), and 3 (23%). In the contV group, serum vancomycin concentration determinations per treatment day were performed significantly less often compared with the intermittent vancomycin infusion group (0.38 [0.15-0.75] vs 0.43 [0.22-1.00], P = .041).

Conclusions

In medical intensive care unit patients, contV is sufficient to achieve target serum vancomycin concentrations. Because contV frequently resulted in subtherapeutic drug levels on the first days of therapy, a higher loading or starting dose might be necessary.     

In-vitro induction of resistance in coagulase-negative staphylococci to vancomycin and teicoplanin

Twenty strains of coagulase-negative staphylococci (18 strains of Staphylococcus haemolyticus and two of S. epidermidis) were serially subcultured in broth media containing subinhibitory concentrations (half the MIC) of either vancomycin or teicoplanin. The MIC of the antibiotic was again measured after five passages in antibiotic-containing broth. The organisms were then subcultured in broth containing antibiotic concentrations half of the new MIC value. The experiment was terminated after 25 passages. Only one strain developed a four-fold increase in vancomycin MIC. On the other hand, 16 strains developed four-fold MIC increases to teicoplanin.     

万古霉素联合腰大池持续引流治疗颅内感染的疗效研究

【目的】探讨万古霉素联合腰大池持续引流（lumbar continuous drainage of fluid ,LCDF）治疗颅内感染的疗效。【方法】选取2014年2月至2016年2月在本院住院治疗的颅内感染患者43例,随机分为万古霉素联合腰大池持续引流治疗组（观察组,23例）和单纯万古霉素治疗组（对照组,20例）,比较两组患者的治疗疗效、治疗前后脑脊液生化指标以及安全性和恢复时间的差异。【结果】观察组治疗有效率显著高于对照组;观察组治疗后白细胞计数、蛋白定量、颅内压均显著低于对照组;葡萄糖显著高于对照组;感染控制时间和症状缓解时间均低于对照组,差异均具有统计学意义（ P ＜00．5）;两组患者治疗后均未出现不良反应。【结论】万古霉素联合腰大池持续引流治疗颅内感染的疗效和恢复时间均优于单纯万古霉素治疗,值得在临床推广应用。     

Using vancomycin concentrations for dosing daptomycin in a morbidly obese patient with renal insufficiency

OBJECTIVE: To report a case in which vancomycin clearance was used to determine the daptomycin dosing interval in a morbidly obese patient with renal impairment. CASE SUMMARY: A 46-year-old man (209 kg; 178 cm) failed a 42 day course of vancomycin therapy for treatment of a methicillin-resistant Staphylococcus aureus-infected wound and cellulitis. The median trough vancomycin concentration was 12.6 microg/mL (range 7.3-24.1) through his course of therapy. Estimation of creatinine clearance (Cl(cr)) was confounded in this clinical scenario, given the patient's weight and a lack of valid equations in this patient population. Daptomycin was administered empirically at 6 mg/kg dosed every 48 hours based on estimated clearance from measured vancomycin concentrations. Steady-state plasma concentrations of daptomycin were determined, and the daptomycin half-life in this patient was more accurately estimated using vancomycin clearance as a surrogate. In addition, a 4 mg/kg dose of daptomycin would have been sufficient based on plasma concentrations. The patient demonstrated rapid clinical improvement and remained free of cellulitis for 6 months after completion of daptomycin and a 12 week course of trimethoprim/sulfamethoxazole. DISCUSSION: The dosing interval of daptomycin is adjusted based on Cl(cr). However, estimation of Cl(cr) is difficult in morbidly obese patients with renal impairment, given a lack of valid equations. In this clinical scenario, vancomycin concentrations were used to estimate Cl(cr) and served as a surrogate measure to determine the daptomycin dosing interval. Measured daptomycin concentrations validated this approach and confirmed the inadequacy of commonly used Cl(cr) equations. CONCLUSIONS: In this clinical scenario, vancomycin concentrations more accurately estimated Cl(cr), thereby facilitating determination of the daptomycin dosing interval.     

In vitro activity of teichomycin and vancomycin alone and in combination with rifampin.

The antibacterial activity of teichomycin, a glycopeptide antibiotic similar to vancomycin, has been evaluated in vitro and compared with that of vancomycin. Test strains included 130 staphylococci and 132 streptococci, with representatives of the major currently recognized species or groups, and lesser numbers of clostridia, propionibacteria, and group JK bacteria. Teichomycin was found to be more active than vancomycin. Its minimum inhibitory concentration (MIC) was two- to fourfold lower than that of vancomycin with staphylococci and anaerobic bacteria, and two- to eightfold lower with streptococci. No significant differences were observed with group JK bacteria. For most strains tested, minimum bactericidal concentrations (MBCs) of both teichomycin and vancomycin either equalled or exceeded by twofold the respective MICs. Higher MBC-to-MIC ratios were obtained for enterococci and pneumococci with both antibiotics. Both teichomycin and vancomycin showed similar in vitro interactions with rifampin in combination tests. Neither antagonism nor (with very few exceptions) synergism occurred.     

Vancomycin removal during a plasma exchange transfusion.

OBJECTIVE: To report a case of clinically significant removal of vancomycin during a plasma exchange transfusion in a patient with sickle-cell anemia. CASE SUMMARY: A 46-year-old African American woman with sickle-cell disease was admitted on three separate occasions and treated with vancomycin. Vancomycin serum drug concentrations were obtained on all three admissions. During one of the admissions, a plasma exchange transfusion was performed the same day vancomycin concentrations were obtained. The vancomycin serum drug concentrations were considerably lower than predicted, resulting in potentially subtherapeutic vancomycin concentrations. Bayesian pharmacokinetic forecasting was used in interpreting the vancomycin concentrations. DISCUSSION: Searches from MEDLINE (1966-September 2000) and Drugs and Pharmacology (1990-September 2000) were performed to obtain pertinent published literature. CONCLUSIONS: Plasma exchange transfusions may result in clinically significant removal of vancomycin from the plasma. The potential exists of underdosing vancomycin in patients who are receiving frequent plasma exchange transfusions. Further research may be warranted to determine whether these patients may be candidates for more frequent and vigilant monitoring of vancomycin concentrations.