Rapid Colloidal Gold Immunoassay for Pharmacokinetic Evaluation of Vancomycin in the Cerebrospinal Fluid and Plasma of Beagle Dogs

Vancomycin (VAN), a glycopeptide antibiotic, is the preferred therapeutic agent for treating Gram-positive bacteria. Rapid and precise quantification of VAN levels in cerebrospinal fluid (CSF) and plasma is crucial for optimized drug administration, particularly among elderly patients. Herein, we introduce a novel clinical test strip utilizing colloidal gold competitive immunoassay technology for the expedient detection of VAN. This test strip enables the detection of VAN concentrations in clinical samples such as plasma within 10 min and has a limit of detection of 10.3 ng/mL, with an inhibitory concentration 50% (IC50) value of 44.5 ng/mL. Furthermore, we used the test strip for pharmacokinetic analysis of VAN in the CSF and plasma of beagle dogs. Our results provide valuable insights into the fluctuations of the drug concentration in the CSF and plasma over a 24 h period after a single intravenous dose of 12 mg/kg. The test strip results were compared with the results obtained via liquid chromatography-mass spectrometry methods, and the measured VAN concentrations in the CSF and plasma via both of the methods showed excellent agreement.

Intrathecal penetration of meropenem and vancomycin administered by continuous infusion in patients suffering from ventriculitis-a retrospective analysis

BACKGROUND

Vancomycin and meropenem are frequently used as empiric treatment for ventriculitis. Penetration into the cerebrospinal fluid (CSF) depends on various factors with a high inter-individual variability. Because attaining and maintaining adequate concentrations of meropenem and vancomycin in the CSF is crucial for their bactericidal effect, we introduced a routine therapeutic drug monitoring (TDM) from CSF and serum for both antibiotics. We studied the antibiotic penetration into the CSF.

METHODS

Patient data including serum and CSF concentrations for meropenem and vancomycin were collected in a retrospective fashion. Antibiotic CSF penetration ratio was calculated for each patient. Antibiotics were administered by continuous infusion aiming for serum target concentrations of 20-30 mg/L for vancomycin and 16-32 mg/L for meropenem.

RESULTS

Twenty-two patients with 36 CSF/serum pairs for meropenem and 43 pairs for vancomycin were studied. No patient suffered from renal or liver insufficiency. Mean vancomycin serum concentration was 22 ± 8 mg/L and the mean CSF concentration 4.5 ± 2.6 mg/L. CSF penetration was 20 ± 11% (coefficient of determination (R²) 0.02). For meropenem, the mean serum concentration was 30.7 ± 14.9 mg/L, mean CSF concentration 5.5 ± 5.2 mg/L, and a penetration of 18 ± 12%, R² = 0.42.

CONCLUSION

Penetration of meropenem and vancomycin into the CSF is low while showing a high interindividual variability. Various patients in our study cohort were at risk for insufficient target attainment in CSF. Continuous administration of antibiotics under routine TDM appears to be a feasible and reasonable approach for optimization of intrathecal drug levels in patients suffering from ventriculitis. TDM might guide individual dosing adaptation and efforts to predict the CSF penetration of meropenem and vancomycin in cases of ventriculitis.

An investigation into the vancomycin concentration in the cerebrospinal fluid due to vancomycin intraventricular administration in newborns: a study of 13 cases

Treatment against shunt infection by transvenous antimicrobial treatment is difficult, with a high risk of relapse. Consequently, to maintain a sufficient cerebrospinal fluid (CSF) concentration, intraventricular administration is utilized in combination with the transvenous administration of vancomycin (VCM). Few studies have so far investigated the optimum administration dose for newborns and the concentration in the CSF. Therefore, we chronologically measured the VCM concentration in the CSF after VCM intraventricular administration in newborns and attempted to elucidate the optimum administration method.The participants consisted of newborns admitted to Juntendo University Neonatal intensive care unit from March 2007 to June 2011 who underwent interventricular shunting placement. VCM was intraventricularly administered to 10 patients for a total of 13 cases. The CSF concentration of VCM was chronologically measured at 12 to 120  hours following the intraventricular administration of VCM.The intraventricular administration groups with VCM of 20 (n = 6) and 10  mg (n = 2) had a high concentration in the CSF at 24  hours following administration (95-168  mg/L), with the concentration remaining high at 72  hours (13.2-72  mg/L). At the same time, in the 5  mg group (n = 5), the concentration in the CSF 24  hours following VCM administration was sufficiently maintained (33.2-62.9  mg/L), with a sufficient trough concentration still maintained at 72  hours (11.7-16.5  mg/L).The concentration in the CSF is prolonged in newborns, thus allowing a sufficient therapeutic range to be maintained even at an intraventricular administration of 5  mg. It is therefore believed that the monitoring of the CSF is very important regarding the administration interval because the VCM concentration in the CSF differs depending on the case.

Simultaneous determination of cefepime and vancomycin in plasma and cerebrospinal fluid by MEKC with direct sample injection and application for bacterial meningitis

A simple MEKC with UV detection at 214 nm for simultaneous analysis of cefepime and vancomycin in plasma and in cerebrospinal fluid (CSF) by direct injection without any sample pretreatment is described. The separation of cefepime and vancomycin from biological matrices was performed at 25 degrees C using a BGE consisting of a Tris buffer with SDS and methanol as the electrolyte solution. Under optimal MEKC conditions for biological samples, good separations with high efficiency and short analysis time are achieved. Several parameters affecting the separation of the drugs from biological matrices were studied, including methanol, pH, and concentrations of the Tris buffer and SDS. The linear ranges of the method for the determination of cefepime and vancomycin in plasma and in CSF using imidazole or cefazolin as an internal standard, respectively, were all over the range of 1-30 microg/mL; the detection limits of cefepime and vancomycin in biological matrices (injection 10 kV, 15 s) were 0.3 and 0.5 microg/mL, respectively. The applicability of the proposed method for the determination of cefepime and vancomycin in plasma and CSF collected after intravenous administration of the drugs in patients with meningitis was demonstrated.

Levels of vancomycin in cerebrospinal fluid of adult patients receiving adjunctive corticosteroids to treat pneumococcal meningitis: a prospective multicenter observational study

BACKGROUND

Evidence from a recent randomized controlled trial suggests that dexamethasone as adjunct therapy in adult pneumococcal meningitis reduces mortality and neurological sequelae. However, adding dexamethasone has the potential to reduce penetration of vancomycin into the cerebrospinal fluid (CSF). We sought to determine concentrations of vancomycin in serum and CSF of patients with suspected or proven pneumococcal meningitis receiving dexamethasone to assess the penetration of vancomycin into the CSF during steroid therapy.

METHODS

In an observational open multicenter study, adult patients admitted to the intensive care unit because of suspected pneumococcal meningitis received recommended treatment for pneumococcal meningitis, comprising intravenous cefotaxime (200 mg per kg of body weight per day), vancomycin (administered as continuous infusion of 60 mg per kg of body weight per day after a loading dose of 15 mg per kg of body weight), and adjunctive therapy with dexamethasone (10 mg every 6 h). Vancomycin levels in CSF were measured on day 2 or day 3 of therapy and were correlated with protein levels in CSF and vancomycin levels in serum (determined at the same time as levels in CSF).

RESULTS

Fourteen patients were included. Thirteen had proven pneumococcal meningitis; 1 patient, initially suspected of having pneumococcal meningitis, was finally determined to have meningitis due to Neisseria meningitidis. Mean levels of vancomycin in serum and CSF were 25.2 and 7.2 mg/L, respectively, and were positively correlated (r=0.6; P=.025). A positive correlation was also found between the ratio of vancomycin in CSF to vancomycin in serum and the level of protein in CSF (r=0.66; P=.01).

CONCLUSIONS

Appropriate concentrations of vancomycin in CSF may be obtained even when concomitant steroids are used. Dexamethasone can, therefore, be used without fear of impeding vancomycin penetration into the CSF of patients with pneumococcal meningitis, provided that vancomycin dosage is adequate. This study is registered at http://www.ClinicalTrials.gov/ (registration number NCT00162578).

[The efficacy of intraventricularly administered vancomycin in the case of central nervous system infection caused by enterococcus faecalis]

The case of 40 years old man with subarachnoid hemorrhage with intraventricular bleeding and with consecutive cerebro-meningitis is presented. The bacterial pathogen was Enterococcus faecalis sensitive only to glycopeptide antibiotics. The standard therapy with intravenously administered Vancomycin and Teicoplanin was not effective. Because of the worsening of patient's clinical status and clinical symptoms of sepsis the intraventricular Vancomycin (20 mg/day) was introduced. At the second day of the therapy the gradual patient's recovery was observed. The symptoms typical for meningitis diminished as well as cerebro-spinal fluid (CSF) parameters normalized. There was no bacterial growth in the blood serum and in CSF. As we can observe the intraventricular administration of Vancomycin is efficient method of cerebro-meningitis treatment. In our opinion the blood-brain barrier, even pathologically changed by infection, do not allow antibiotics to penetrate CSF, even in the maximal intravenous doses. In the cases of cerebro-meningitis caused by bacteria sensitive only to glycopeptide antibiotics, the intraventricular administration of the drug might be an alternative way of therapy especially when the doses of intravenous antibiotics need to be reduced.

The effect of netilmicin and vancomycin on lipid peroxidation processes in cerebrospinal fluid in children with hydrocephalus

In biological systems, it is difficult to determine free radicals because of their reactivity and their very short time of existence. On the basis of markers, which come into being as a result of radical processes, one might believe that there exist reactive oxygen species. One of the determinants of free radical activity of oxygen is the presence of malondialdehyde (MDA), a final product of lipid peroxidation. This study aimed at finding the answer to the question whether the concentration of netylmicin and vancomycin influences the amount of substances reacting with thiobarbituric acid (TBA) in cerebrospinal fluid (CSF) in children with hydrocephalus. Applying the TBA test for examinations with antibiotics added both in vivo and in vitro, we could demonstrate that increased concentration of the examined antibiotics in cerebrospinal fluid reduces the amount of MDA. The results obtained demonstrate that products of lipid peroxidation are present in the CSF samples analyzed. In this study, we found that the concentration of vancomycin and netilmicin influenced the lipid peroxidation process in cerebrospinal fluid in children with hydrocephalus, thus confirming anti-inflammatory properties of the antibiotics applied.

Experimental study of the efficacy of vancomycin, rifampicin and dexamethasone in the therapy of pneumococcal meningitis

The object of the study was to assess the efficacy of rifampicin and the combination of rifampicin plus vancomycin in a rabbit model of experimental penicillin-resistant pneumococcal meningitis. We also studied the effect of concomitant dexamethasone on the CSF antibiotic levels and inflammatory parameters. The rabbit model of pneumococcal meningitis was used. Groups of eight rabbits were inoculated with 106 cfu/mL of a cephalosporin-resistant pneumococcal strain (MIC of cefotaxime/ceftriaxone 2 mg/L). Eighteen hours later they were treated with rifampicin 15 mg/kg/day, vancomycin 30 mg/kg/day or both plus minus dexamethasone (0.25 mg/kg/day) for 48 h. Serial CSF samples were withdrawn to carry out bacterial counts, antibiotic concentration and inflammatory parameters. Rifampicin and vancomycin promoted a reduction of >3 log cfu/mL at 6 and 24 h, and cfu were below the level of detection at 48 h. Combination therapy with vancomycin plus rifampicin was not synergic but it had similar efficacy to either antibiotic alone and it was able to reduce bacterial concentration below the level of detection at 48 h. Concomitant use of dexamethasone decreased vancomycin levels when it was used alone (P< 0.05), but not when it was used in combination with rifampicin. Rifampicin alone at 15 mg/kg/day produced a rapid bactericidal effect in this model of penicillin-resistant pneumococcal meningitis. The combination of vancomycin and rifampicin, although not synergic, proved to be equally effective. Using this combination in the clinical setting may allow rifampicin administration without emergence of resistance, and possibly concomitant dexamethasone administration without significant interference with CSF vancomycin levels.

Cerebrospinal fluid penetration and pharmacokinetics of vancomycin administered by continuous infusion to mechanically ventilated patients in an intensive care unit

Cerebrospinal fluid (CSF) penetration and the pharmacokinetics of vancomycin were studied after continuous infusion (50 to 60 mg/kg of body weight/day after a loading dose of 15 mg/kg) in 13 mechanically ventilated patients hospitalized in an intensive care unit. Seven patients were treated for a sensitive bacterial meningitis and the other six patients, who had a severe concomitant neurologic disease with intracranial hypertension, were treated for various infections. Vancomycin CSF penetration was significantly higher (P < 0.05) in the meningitis group (serum/CSF ratio, 48%) than in the other group (serum/CSF ratio, 18%). Vancomycin pharmacokinetic parameters did not differ from those obtained with conventional dosing. No adverse effect was observed, in particular with regard to renal function.

Meropenem alone and in combination with vancomycin in experimental meningitis caused by a penicillin-resistant pneumococcal strain

In a rabbit model of meningitis caused by a pneumococcus highly resistant to penicillin (MIC, 4 microg/ml), meropenem, a broad-spectrum carbapenem, was bactericidal (-0.48+/-0.14 deltalog10 cfu/ml h) and slightly superior to ceftriaxone (-0.34+/-0.23 deltalog10 cfu/ml x h) and vancomycin (-0.39+/-0.19 deltalog10 cfu/ml x h). Although the combination of vancomycin with ceftriaxone was significantly more active than ceftriaxone alone (-0.55+/-0.19 deltalog10 cfu/ml x h), only an insignificant gain was observed by the addition of vancomycin to meropenem (-0.55+/-0.28 deltalog10 cfu/ml x h).

Bactericidal activity of vancomycin in cerebrospinal fluid

Intraventricular application of vancomycin is an effective therapeutic regimen for the treatment of shunt-associated staphylococcal ventriculitis. We examined the in vitro activity of vancomycin at high concentrations against Staphylococcus aureus ATCC 25923 and Staphylococcus epidermidis ATCC 12228 in human cerebrospinal fluid samples. Time-kill curves revealed equal efficacies for concentrations of 10, 100, and 300 microg/ml, and incubation times of 24 to 48 h were needed to achieve a 3 log(10) reduction of viable bacteria. A concentration of 5 microg/ml showed a slightly lower activity, but this difference was not significant. In an infant who was successfully treated for shunt-associated ventriculitis due to S. epidermidis by once-daily local administration of vancomycin (3 mg for 2 days and 5 mg for 4 days [0. 5 to 0.8 mg/kg of body weight]) the in vivo kill kinetics were similar to those for the in vitro results. These results support time-dose regimens that provide trough vancomycin levels of 5 to 10 microg/ml.

Trovafloxacin in combination with vancomycin against penicillin-resistant pneumococci in the rabbit meningitis model

Trovafloxacin, a new fluoroquinolone, produced bactericidal activity (-0.33 +/- 0.13 delta log10 CFU/ml.h; intravenously [i.v.] administered dose, 15 mg/kg) comparable to that of vancomycin (-0.39 +/- 0.18 delta log10 CFU/ml.h; i.v. admininistered dose, 20 mg/kg) in the treatment of experimental meningitis in rabbits due to a pneumococcal strain highly resistant to penicillin (MIC of penicillin G, 4 micrograms/ml). The combination of both drugs significantly increased (P < 0.05) the killing rate (-0.60 +/- 0.23 delta log10 CFU/ml.h) compared to that produced by either monotherapy. These results were also confirmed in vitro.

Pharmacodynamics of vancomycin for the treatment of experimental penicillin- and cephalosporin-resistant pneumococcal meningitis

With the emergence of beta-lactam antibiotic resistance among strains of Streptococcus pneumoniae, vancomycin has assumed an important role in the treatment of bacterial meningitis. Using the rabbit meningitis model, we evaluated the pharmacokinetics and pharmacodynamics of vancomycin in this setting. Animals were given 80 mg/kg of body weight daily in two or four divided doses to determine the penetration and activity of vancomycin in cerebrospinal fluid (CSF); each regimen was administered with and without dexamethasone. Mean peak (2 h) concentrations in CSF that were four- to eightfold higher than the minimum bactericidal concentration (MBC; 0.5 microgram/ml) for the pathogen were adequate for bacterial clearance. In both groups concentrations in CSF remained higher than the MBC for greater than 80% of the respective dosing intervals, and the penetration of vancomycin into CSF was 20%. Mean concentrations in CSF at 24 to 36 h of therapy were lower than those achieved during the first 12 h, consistent with a decline in the level of antibiotic entry into CSF as inflammation wanes. Rates of bacterial clearance were similar for the two regimens, and for all animals cultures of CSF were sterile by 36 h. The coadministration of dexamethasone significantly reduced the penetration of vancomycin into CSF by 29% and significantly lowered the rate of bacterial clearance during the first 6 h in animals receiving 20-mg/kg doses of vancomycin. For animals receiving 40-mg/kg doses, therapeutic peak concentrations in CSF were obtained even with steroid use, suggesting that the effect of steroids may be circumvented by the use of larger daily doses of vancomycin.

Comparative in vitro killing activities of meropenem, imipenem, ceftriaxone, and ceftriaxone plus vancomycin at clinically achievable cerebrospinal fluid concentrations against penicillin-resistant Streptococcus pneumoniae isolates from children with meningitis

The activities of meropenem, imipenem, ceftriaxone, and vancomycin were evaluated against 80 penicillin-susceptible and -resistant Streptococcus pneumoniae strains. Meropenem, imipenem, ceftriaxone, and vancomycin MICs at which 90% of the isolates are inhibited were 0.5, 0.25, 1, and 0.25 microg/ml, respectively. Against penicillin-resistant strains, the best killing activity at cerebrospinal fluid concentrations was obtained with imipenem and ceftriaxone-vancomycin. However, while the killing activity of imipenem was significantly greater than that of meropenem, no significant difference was observed between the activities of meropenem and ceftriaxone-vancomycin.

Bactericidal activity against intermediately cephalosporin-resistant Streptococcus pneumoniae in cerebrospinal fluid of children with bacterial meningitis treated with high doses of cefotaxime and vancomycin

Cerebrospinal fluid (CSF) was taken from 19 children with bacterial meningitis treated with cefotaxime (300 mg/kg of body weight/day) and vancomycin (60 mg/kg/day). Median levels of drugs in CSF were smaller than expected, as follows: 4.4 microg/ml for cefotaxime, 3.2 microg/ml for desacetylcefotaxime, and 1.7 microg/ml for vancomycin. The median CSF bactericidal titer against an intermediately cefotaxime-resistant pneumococcus was 1:4. Our data suggest at least an additive interaction between the drugs used in this study.

Cerebrospinal fluid (CSF) pharmacokinetics of intraventricular vancomycin in patients with staphylococcal ventriculitis associated with external CSF drainage

We studied the efficacy and pharmacokinetics of intraventricularly administered vancomycin in three patients with shunt-associated staphylococcal ventriculitis. We instilled 10 mg of the drug intraventricularly every 24 hours. Cerebrospinal fluid (CSF) levels were measured 1 hour after instillation and then every 2 hours. Peak vancomycin levels reached a mean of 292.9 microg/mL. The mean trough levels, measured immediately before readministration of vancomycin, were 7.6 microg/mL; this level has proved to be sufficient for maintaining the necessary steady-state serum concentration of vancomycin. All three patients were cured clinically and bacteriologically, and CSF parameters returned to normal within 5-13 days. No side effects were observed. Our results suggest that intraventricularly administered vancomycin is a valuable therapeutic strategy for treating shunt-associated staphylococcal ventriculitis. In addition, we provide evidence that 10 mg of vancomycin, administered intraventricularly every 24 hours, allows maintenance of therapeutic drug levels in the CSF for at least 24 hours.

[Adequate intrathecal diffusion of teicoplanin after failure of vancomycin, administered in continuous infusion in three cases of shunt associated meningitis]

Glycopeptides which have excellent in vitro activity against the Gram-positive causal agents of meningitis unfortunately have a poor CSF penetration. Vancomycin distribution into CSF is improved when administered by a continuous intravenous route and staphylococcal shunt related infection have been reported to be cured. Teicoplanin has good in vitro activity against a lot of staphylococci, and activity superior to vancomycin, against streptococci and is less toxic. In three children with shunt ventriculitis (S epidermidis 2, S. faecalis 1) despite a continuous infusion, vancomycin 15 mg/kg over 60 minutes onset, then 50 mg/kg/day was clinically and bacteriologically ineffective with very poor CSF levels even if high blood levels. After failure of vancomycin we used teicoplanin as a continuous i.v. infusion 6 mg/kg over 60 mn onset, then 12 mg/kg/day. This treatment was quickly effective and well tolerated.

Bactericidal activity against cephalosporin-resistant Streptococcus pneumoniae in cerebrospinal fluid of children with acute bacterial meningitis

There are reports of failure of extended-spectrum cephalosporin treatment in pneumococcal meningitis. On the basis of in vitro and animal experimental studies, the addition of vancomycin or rifampin to an extended-spectrum cephalosporin has been recommended for empiric treatment of these patients. Cerebrospinal fluid (CSF) was taken from 31 children with bacterial meningitis randomized to receive ceftriaxone alone (n = 11), ceftriaxone plus rifampin (n = 10), or ceftriaxone plus vancomycin (n = 10). The CSF from children receiving ceftriaxone alone was unable to kill intermediately ceftriaxone-resistant or fully resistant strains when the concentration of ceftriaxone in the CSF was less than 5 micrograms/ml. At higher concentrations bactericidal activity was present. We have shown that vancomycin penetrates reliably into the CSF of children with acute meningitis, which is in contrast to previous studies with adults. The addition of vancomycin or rifampin to ceftriaxone resulted in significantly enhanced CSF bactericidal activity compared with that of ceftriaxone alone against these resistant strains. Our data suggest that the addition of rifampin or vancomycin to ceftriaxone may be useful for the treatment of cephalosporin-resistant pneumococcal meningitis.

[Continuous infusion of vancomycin in post-neurosurgical staphylococcal meningitis in adults]

Eight adult patients with post-surgery meningitis caused by methicillin-resistant staphylococci were treated with continuous intravenous infusion of vancomycin in mean doses of 50 mg/kg/day. This treatment, which lasted 3 to 6 weeks, was well tolerated by the kidneys and resulted in cure in all cases; its effect on the ear was not evaluated. Stable concentrations of 4 to 7 mg/l in cerebrospinal fluid were obtained after the 48th hour of treatment.

Vancomycin administration into the cerebrospinal fluid: a review

OBJECTIVE

To discuss administering vancomycin directly into the cerebrospinal fluid (CSF) to treat serious central nervous system (CNS) infections.

DATA SOURCES

References were obtained through an online search of MEDLINE, limited to material published in English. In addition, information was extracted from clinical trials, review articles, abstracts, and textbooks.

STUDY SELECTION

Systematic evaluation of this topic in humans has not been done in a prospective manner. Related research articles describing the pathophysiology of CNS infections, intrathecal drug administration, and case reports of CSF vancomycin administration were reviewed.

DATA EXTRACTION

Case reports regarding CSF vancomycin dosing were evaluated and included: drug dosing, infecting organism, infectious disease state, infectious outcome, CSF dynamics/flow abnormalities, methods of drug administration, drug monitoring, and toxicities.

DATA SYNTHESIS

The results of this review are based on qualitative evaluations of anecdotal case reports and a basic understanding of intrathecal and intraventricular drug dosing principles. CSF administration of vancomycin is an effective means of bypassing the blood-brain barrier to achieve greater drug concentrations within the CSF. Current limitations to the CSF administration of vancomycin include a lack of data describing its safety, efficacy, and pharmacokinetics.

CONCLUSIONS

CNS infections may require the CSF administration of vancomycin for successful eradication. Recommendations for dosing in the literature vary. Because of the potential toxicities associated with elevated CSF concentrations of vancomycin, dosing should be conservative.

[Transferability of vancomycin to cerebrospinal fluid in rabbits with meningitis caused by Staphylococcus aureus]

The transferability of vancomycin (VCM) to cerebrospinal fluid (CSF) was studied employing rabbits with experimental meningitis caused by Staphylococcus aureus. VCM was administered intravenously for 30 minutes at a dose level of 30 mg/kg. Serum concentration reached a maximum of 75 +/- 3.80 micrograms/ml (mean +/- S.E.) at the completion of administration (i.e., 30 minutes) and CSF concentration reached a maximum of 2.4 +/- 0.39 micrograms/ml at 60 minutes. Pharmacokinetic parameters calculated from this concentration-time curve were as follows: Cmax (CSF/Serum) 3.21%, AUC (CSF/Serum) 2.39% between 15 and 60 minutes, 3.99% between 15 and 120 minutes, and 4.40% between 15 and 150 minutes. T 1/2 for VCM in CSF: 143 minutes, T1/2 (CSF/Serum):2.09. Based on this investigation, VCM appears to be effective in the treatment of meningitis caused by MRSA (Methicillin-resistant S. aureus).

Measurement of antimicrobial agents in cerebrospinal fluid using the Abbott TDx analyzer

Occasionally, requests are made by our physicians for the measurement of gentamicin, tobramycin, or vancomycin in cerebrospinal fluid (CSF) specimens during the course of treating patients for bacterial meningitis. We evaluated CSF as a specimen type for the measurement of amikacin, gentamicin, tobramycin, and vancomycin on the Abbott TDx analyzer. Coefficients of variation for CSF spiked with these antimicrobial agents ranged from 0.8% to 6.5% for intra-assay values and from 2.1% to 2.3% for inter-assay values. Serum and CSF specimens were spiked at various levels with equal amounts of the antibiotics. Correlation coefficients for serum vs. CSF for these agents were 0.999. Recoveries ranged from 86% to 134%. Sensitivity for these assays is about fourfold better for CSF than for serum. CSF appears to be an acceptable specimen type for the measurement of these antibiotics using the Abbott TDx analyzer.

Evaluation of vancomycin for therapy of adult pneumococcal meningitis

The emergence of pneumococci resistant to penicillin and other agents prompted us to evaluate intravenous vancomycin for the therapy of pneumococcal meningitis, which has an overall mortality of 30%. Eleven consecutive adult patients with cerebrospinal fluid (CSF)-culture-proven pneumococcal meningitis and positive initial CSF Gram stain were given intravenous vancomycin (usual dosage, 7.5 mg/kg every 6 h for 10 days). The MBCs of vancomycin ranged from 0.25 to 0.5 micrograms/ml. Early adjunctive therapy with intravenous dexamethasone, mannitol, and sodium phenytoin was also instituted. After 48 h of therapy, all 11 patients showed a satisfactory clinical response, although the CSF culture remained positive in one case; median trough CSF and serum vancomycin levels were 2 and 5.1 micrograms/ml, respectively, and trough CSF bactericidal titers ranged from less than 1:2 to 1:16. On day 3, one patient died of acute heart failure. Four patients had clinical failure at on days 4 (two patients), 7 (one), and 8 (one) of therapy; they all immediately responded to a change in antibiotic therapy. The remaining six patients were cured after 10 days of vancomycin therapy. At this point, median peak CSF and serum vancomycin levels were 1.9 and 18.5 micrograms/ml, respectively. A transient alteration of renal function occurred in two patients, and persistent slight hypoacusia occurred in three patients. In summary, 11 adults with pneumococcal meningitis were treated with vancomycin and early adjunctive therapy including dexamethasone. All patients initially improved, and 10 were ultimately cured of the infection. However, four patients experienced a therapeutic failure, which led to a change in vancomycin therapy.

Vancomycin pharmacokinetics in hydrocephalic shunt prophylaxis and relationship to ventricular volume

Vancomycin pharmacokinetics were determined in 25 patients receiving ventriculoperitoneal shunts for hydrocephalus. Computed tomography scan-derived ventricular-brain ratio as an expression of hydrocephalus varied between 9.3% and 15.4% (12.9% +/- 1.7%). One hour prior to surgery each patient received 1 g of vancomycin infused intravenously over 60 minutes. Samples of cerebrospinal fluid and venous blood were obtained 1 hour later and vancomycin levels assayed by fluorescence polarization immunoassay. There were 11 females and 14 males, with a mean age of 44.5 +/- 10.3 years and a mean weight of 72.0 +/- 11.4 kg. All had normal renal function. Levels of vancomycin in the cerebrospinal fluid at 1 hour ranged from 0.1 to 1.5 micrograms/mL (0.9 +/- 0.3). Weight did not affect these values (p greater than 0.1). Simultaneous blood vancomycin levels varied between 9.1 and 38.7 micrograms/mL (22.3 +/- 8.3). Ventricular volume, expressed as the ventricular-brain ratio, did not correlate with cerebrospinal fluid vancomycin levels (p greater than 0.5). There was no significant increase in concentrations of vancomycin in CSF as cerebrospinal fluid protein concentration increased, nor when blood vancomycin concentration was greater than 20 mg/dL (therapeutic range) (p greater than 0.1). No patient had evidence of infection at 6 months follow up. These results indicate minimal cerebrospinal fluid penetrance of vancomycin when administered systemically 1 hour prior to shunt surgery. In addition concentrations of vancomycin in cerebrospinal fluid bear no relationship to weight, ventricular volume, meningeal inflammation, or blood levels in the therapeutic range. The minimum inhibitory concentration of vancomycin for staphylococci is 1.5 to 3.1, and as bactericidal levels of 5 to 8 minimum inhibitory concentration are needed to kill organisms, a combination of both systemic and intraventricular vancomycin may be needed to ensure adequate cerebrospinal fluid and tissue concentration of antibiotic during shunt prophylaxis.

Pharmacokinetics and cerebrospinal fluid (CSF) concentrations of vancomycin in pediatric patients undergoing CSF shunt placement

Staphylococcus epidermidis has been established as the common pathogen causing cerebrospinal fluid shunt infections. In addition, clinical isolates of S. epidermidis from infected shunts are typically resistant to methicillin. Vancomycin is often used for neurosurgical prophylaxis due to its excellent in vitro activity against methicillin-resistant staphylococci. Limited data are available about the pharmacokinetics and cerebrospinal fluid concentrations of vancomycin in pediatric patients intraoperatively. The objectives of this study were to characterize the pharmacokinetics and determine the cerebrospinal fluid concentrations of vancomycin. Eight patients (mean age 8.3 +/- 7.0 years) received three doses of intravenous vancomycin, 15 mg/kg every 6 h. The first dose was administered 1 h prior to surgery. Blood samples were collected at 0, 0.5, 1, 2, 4, and 5 h after the end of the infusion. A cerebrospinal fluid sample was collected at the time of shunt insertion. Urine samples were collected over a 24-hour period. Vancomycin was measured with a fluorescence polarization immunoassay. The peak serum concentrations ranged from 15.6 to 33.7 micrograms/ml; cerebrospinal fluid concentrations ranged from less than 0.6 to 0.8 microgram/ml. The mean total clearance, renal clearance, apparent volume of distribution, and elimination half-life were 0.11 +/- 0.05 l/h/kg, 0.07 +/- 0.02 l/h/kg, 0.54 +/- 0.15 l/kg, and 4.8 +/- 4.0 h, respectively. Approximately 70% of total vancomycin dose was excreted in the urine. A 2- to 5-fold variation in total clearance and a 2.5-fold variability in renal clearance were observed. Low cerebrospinal fluid concentrations of vancomycin were present at the time of shunt insertion in these pediatric patients.(ABSTRACT TRUNCATED AT 250 WORDS)

[Diffusion of vancomycin in the cerebrospinal fluid, in the dog, in the absence of meningeal inflammation]

The diffusion of vancomycin into the cerebro-spinal fluid was studied in 5 healthy dogs. Its appears that vancomycin does diffuse across the blood-brain barrier. Though the concentrations reached in the CSF are low, they are of the same order of magnitude as the minimal inhibitory concentrations of this antibiotic towards the germs usually treated. The usual pharmacokinetic parameters were determined.

[Ventricular staphylococcal infections. Treatment with vancomycin by continuous venous infusion]

Thirteen cases of meningeal and/or ventricular infection and 1 case of septicaemia, all caused by staphylococci, were treated with continuous intravenous infusions of vancomycin. Repeated measurements of vancomycin plasma and CSF levels by microbiological assay or by high performance liquid chromatography showed that the antibiotic entered the CSF after 48 hours of treatment and that its concentrations in CSF remained stable at 1 to 4 micrograms/ml (mean: 2 micrograms/ml) throughout the 3 weeks' treatment period. After treatment was discontinued, vancomycin became undetectable in CSF within less than 24 hours. All the children were cured.

Pharmacokinetics of intraventricular vancomycin in hydrocephalic rats

An animal model was developed for studying the pharmacokinetics of antibiotics administered intraventricularly in hydrocephalus. Obstructive hydrocephalus was consistently produced in craniectomized adult rats by injecting kaolin into the cisterna magna. After induction of hydrocephalus, vancomycin was injected into the right lateral ventricle of each rat. Bilateral ventricular cerebrospinal fluid (CSF) and brain parenchymal samples were obtained at 0.5, 1, 2, 4, 8, and 12 hours and the concentration of vancomycin in these samples was determined. Brain tissue was also analyzed histologically. The results show: (a) vancomycin is rapidly distributed within the CSF, including the contralateral ventricle, within 30 minutes; (b) vancomycin concentrations were nearly identical in both ventricles at all time points; (c) mean peak CSF vancomycin concentrations occurred at 2 hours and were 23.8 and 21.3 micrograms/ml for the left and right lateral ventricles, respectively; (d) elimination from CSF was slow (T1/2 beta = 2.22 hours, T1/2 gamma = 19.65 hours); (e) no vancomycin was detected (less than or equal to 2 micrograms/g) in the samples of periventricular white matter; (f) histological changes observed were consistent with untreated obstructive hydrocephalus and did not seem to be related to vancomycin treatment. The clinical significance of these results and the usefulness of the experimental model are discussed.

Pharmacokinetics of vancomycin

Vancomycin is poorly absorbed when administered by mouth and, for systemic infections, must be given intravenously. The pharmacokinetics of vancomycin have been well defined in a number of recent studies in man. Since the drug is excreted primarily via the kidneys, dosage modification is imperative in patients with impaired renal function. With the possible exception of aqueous humour and cerebrospinal fluid, vancomycin penetrates well into most body fluids. It appears that excessively high serum concentrations of vancomycin may be associated with ototoxicity. It has not been possible to relate the development of nephrotoxicity to determined previously serum concentrations of vancomycin.

Effect of mannitol infusions into the internal carotid artery on entry of two antibiotics into the cerebrospinal fluid and brains of normal rabbits

The rapid infusion of hyperosmolar solutions into the internal carotid artery transiently disrupts the integrity of the blood-brain barrier, permitting entry of substances normally excluded from the nervous system. This study examined the effect of such an infusion on the penetration of vancomycin and tobramycin into the cerebrospinal fluid and brains of normal rabbits. Groups of five to seven animals were assigned either to control groups, receiving vancomycin or tobramycin alone, or to experimental groups, receiving these antibiotics with 40-s intracarotid infusions of 8.0 ml of 25% mannitol. Serum, cerebrospinal fluid, and brain specimens were obtained for assay 135 min after dosage. Concentrations of these antibiotics in serum were comparable in control and experimental groups; concentrations of the antibiotics in cerebrospinal fluid were significantly higher in the experimental groups. Mean (+/- standard deviation) concentrations of the antibiotics in cerebrospinal fluid were, respectively, less than 0.5 and 4.1 +/- 4.6 micrograms of vancomycin per ml and 0.6 +/- 0.5 and 3.4 +/- 2.4 micrograms of tobramycin per ml in the control and experimental groups. The concentrations of these antibiotics in brains were also higher in the experimental groups. This trend achieved statistical significance in the tobramycin studies, where control animals uniformly had tobramycin concentrations in brains of less than 0.1 microgram/g and experimental group animals had a mean concentration of 0.4 microgram/g. Additional studies with tobramycin indicated that intracarotid antibiotic administration immediately after the mannitol infusion further augmented antibiotic concentrations in brains.

Vancomycin in rabbits: pharmacokinetics, extravascular diffusion, renal excretion and interactions with furosemide

The pharmacokinetics, renal excretion, protein binding and extravascular diffusion of vancomycin in rabbits were studied. The effects of furosemide on these different parameters also were investigated. We observed a T 1/2 of 55 min and protein binding of 65% as determined in vitro by equilibrium dialysis. Vancomycin appeared to be secreted by renal tubules (fractional excretion: 177 +/- 44%). In vitro, furosemide (5 micrograms/ml) slightly decreased the vancomycin protein binding (from 65 to 57%). Furosemide significantly increased the renal excretion of vancomycin, through a tubular process without any effect on the filtered load. Vancomycin appeared slowly and at low concentrations in the extravascular fluid. The extravascular concentrations were higher when the antibiotic was administered by a 6-hr continuous infusion than when given by a 20-min infusion of the same dose. Our results suggested that the in vivo antibacterial effect to vancomycin could be enhanced by prolonged infusion. Also, it was demonstrated that furosemide has only a small effect on the kinetics of vancomycin.

Vancomycin for treatment of bacterial meningitis

Clinical experience with vancomycin for the treatment of bacterial meningitis has not been extensive. Presently available data indicate that when meningeal inflammation is present intravenously administered vancomycin penetrates into cerebrospinal fluid and therapeutically effective levels of drug therein are frequently attained. Treatment of meningitis with vancomycin has been effective in clinical situations that precluded the use of the commonly administered agents, i.e., in infections due to resistant strains or to unusual organisms, in patients allergic to penicillin, and in patients for whom therapy with a first-choice antibiotic has failed. When response to intravenously administered vancomycin was unsatisfactory, the addition of intrathecal therapy resulted in a favorable outcome in some patients. Combination therapy with agents that act synergistically with vancomycin has been beneficial. Vancomycin warrants serious consideration as a useful alternate antibiotic for the treatment of bacterial meningitis.

Vancomycin and rifampin therapy for Staphylococcus epidermidis meningitis associated with CSF shunts: report of three cases

Three patients with Staphylococcus epidermis meningitis associated with cerebrospinal fluid (CSF) shunt devices were treated with a combination of intravenous vancomycin and oral rifampin. Two of the isolates were methicillin-resistant. All patients had a favorable clinical response. Time-kill curves showed that the addition of rifampin to vancomycin resulted in enhanced bactericidal activity against all isolates when compared to either antibiotic alone. This finding suggests that the combination of oral rifampin and intravenous vancomycin may be useful in the treatment of methicillin-resistant and recalcitrant methicillin-sensitive S. epidermis meningitis associated with CSF shunts. In vitro susceptibility testing should be performed.

Effect of meningitis and probenecid on the penetration of vancomycin into cerebrospinal fluid in rabbits

This study examined the effects of experimental pneumococcal meningitis and probenecid administration on the penetration of parenterally administered vancomycin into cerebrospinal fluid in rabbits. Bacterial killing was also examined in infected animals. Meningitis was induced by intracisternal inoculation of Streptococcus pneumoniae. Vancomycin was administered in a loading dose followed by a continuous intravenous infusion for 6 h. Serum and cerebrospinal fluid samples were obtained at 0, 2, 4, and 6 h for antibiotic assays and quantitative cultures. Meningitis significantly enhanced the penetration of vancomycin into cerebrospinal fluid, but probenecid administration had no effect. In normal rabbits, at 6 h the mean percent penetration (cerebrospinal fluid concentration/serum concentration x 100%) +/- the standard deviation was 1.9 +/- 0.9% in the nonprobenecid group (n = 10) and 1.9 +/- 1.1% in the probenecid group (n = 9). In rabbits with experimental pneumococcal meningitis, the mean percent penetration at 6 h was 3.9 +/- 2.6% in the nonprobenecid group (n = 11) and 4.3 +/- 2.1% in the probenecid group (n = 9). Mean bacterial titers in the cerebrospinal fluid of infected animals decreased by more than 3.0 log 10 colony-forming units per ml in both the nonprobenecid and the probenecid groups.

Vancomycin penetration into CSF during treatment of patients receiving hemodialysis

Penetration of vancomycin into CSF was determined during therapy with the regimens recently used to treat staphylococcal infections in patients receiving hemodialysis: 1 gm weekly or 750 mg twice weekly. During three episodes in two patients with proved or suspected central nervous system infection, CSF levels of vancomycin ranged from < 0.5 to 1.54 microgram/ml; in only two of six CSF specimens did the antibiotic level exceed its in vitro inhibitory concentration for the infecting organism. Thus, the vancomycin hemodialysis regimens may provide marginal to subtherapeutic CSF drug levels.