Vancomycin administration into the cerebrospinal fluid: a review

Spinal arachnoiditis followed by intrathecal tigecycline therapy for central nervous system infection by extremely drug-resistant Acinetobacter baumannii

In prior research, intrathecal tigecycline was successfully used to treat central nervous system infection by extensively drug-resistant Acinetobacter baumannii. However, little is known about its safe dose and adverse reactions. This study reports the case of a 28-year-old male patient who was diagnosed with central nervous system infection by extensively drug-resistant A. baumannii after the removal of a ventriculoperitoneal shunt. Intravenous and intrathecal tigecycline were administrated simultaneously. Spinal arachnoiditis was discovered after nine doses of intrathecal tigecycline. Spinal arachnoiditis was resolved after discontinuation of the antibiotic. This is the first report of an adverse reaction to intrathecal tigecycline. The case was complicated by spinal arachnoiditis, which obstructed the assessment of cerebrospinal fluid. The appropriate dose and administration schedule of intrathecal tigecycline remain to be determined.

Intracerebroventricular drug administration

Among the various routes of drug administration, perhaps the least studied is intracerebroventricular (ICV) administration. This route has been shown to be particularly useful in administering to the central nervous system (CNS) drugs that do not cross the blood-brain barrier readily. As such, the ICV route is a valuable option for providing therapeutic CNS drug concentrations to treat patients with CNS infectious and neoplastic diseases. This route of drug administration also has the advantage of minimizing systemic toxicity.

Intracerebroventricular Delivery as a Safe, Long-Term Route of Drug Administration

Intrathecal delivery methods have been used for many decades to treat a broad range of central nervous system disorders. A literature review demonstrated that intracerebroventricular route is an established and well-tolerated method for prolonged central nervous system drug delivery in pediatric and adult populations. Intracerebroventricular devices were present in patients from one to 7156 days. The number of punctures per device ranged from 2 to 280. Noninfectious complication rates per patient (range, 1.0% to 33.0%) were similar to infectious complication rates (0.0% to 27.0%). Clinician experience and training and the use of strict aseptic techniques have been shown to reduce the frequency of complications.

Central Nervous System Infections in the Critically Ill

Central nervous system (CNS) infections are frequently encountered in the intensive care unit setting and are a significant source of morbidity and mortality. The constantly changing trends in microbial resistance, as well as the pharmacokinetic difficulties in providing effective concentrations of antimicrobials at the site of infection represent a unique challenge to clinicians. Achievement of a successful outcome in patientswith CNS infections is reliant on eradication of the offending pathogen and management of any neurologic complications. This requires an anatomic and physiologic understanding of the different types of CNS infection, diagnostic strategies, associated complications, causative organisms, and the principles that govern drug distribution into the CNS. This article serves as a review of the epidemiology, pathophysiology, diagnosis, and treatment options for a variety of CNS infections, with a focus on those commonly encountered in an intensive care setting.

Postneurosurgical Central Nervous System Infection Due to Enterococcus faecalis Successfully Treated With Intraventricular Vancomycin

Infections from Enterococcus faecalis and Enterococcus faecium are uncommon in the post-neurosurgical intervention setting., [1, 2, 3, 4] Intraventricular antibiotics are recommended when standard intravenous therapy fails. [5] Here we present a case of post-neurosurgical ventriculitis, meningitis, and cerebritis in an oncology patient caused by refractory Enterococcus faecalis successfully treated with intraventricular vancomycin.

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.

Systematic review of efficacy, pharmacokinetics, and administration of intraventricular vancomycin in adults

Central nervous system infections requiring treatment with intraventricular (IVT) vancomycin are becoming increasingly common with advent of intracranial devices and increasing prevalence of multi-drug resistant and nosocomial organisms. Administering vancomycin via IVT route bypasses the blood-brain barrier to allow localized and controlled delivery directly to the desired site of action, achieving high concentrations for more reliable bactericidal action. This article systematically reviews current literature on IVT vancomycin in adults, compiles current knowledge, and integrates available evidence to serve as a practical reference.Medline (1946-July 2012), Embase (1974-July 2012), and International Pharmaceutical Abstracts (1970-July 2012) were searched using terms vancomycin, intraventricular, shunt infection, cerebrospinal fluid, and intraventriculitis. Seventeen articles were included in this review. Indications for IVT vancomycin included meningitis unresponsive to intravenous antibiotics, ventriculitis, and intracranial device infections. No serious adverse effects following IVT vancomycin have been reported. Dosages reported in literature ranged from 0.075-50 mg/day, with the most evidence for dosages of 5 to 20 mg/day. Duration of therapy most commonly ranged from 7 to 21 days. Therapeutic drug monitoring was reported in 11 studies, with CSF vancomycin levels varying widely from 1.1 to 812.6 mg/L, without clear relationships between CSF levels and efficacy or toxicity. Using IVT vancomycin to treat meningitis, ventriculitis, and CNS device-associated infections appears safe and effective based on current evidence. Optimal regimens are still unclear, and dosing of IVT vancomycin requires intricate consideration of patient specific factors and their impact on CNS pathophysiology. Higher-quality clinical trials are necessary to characterize the disposition of vancomycin within CNS, and to determine models for various pathophysiological conditions to facilitate better understanding of effects on pharmacokinetic and pharmacodynamic parameters.

Fluctuations in vancomycin CNS tissue concentrations following intermittent and continuous infusions in the rat

The purpose of this investigation was to compare the variability of vancomycin concentrations in the serum and CNS when administered continuously or as intermittent intravenous infusions in the rat. The hypothesis for this investigation was that the magnitude of change in serum vancomycin concentrations directly relates to the extent of vancomycin concentration fluctuations in the CNS. Microdialysis and serum sampling techniques were employed and biologic samples were analysed for vancomycin using HPLC. Over the dosing interval, the mean changes in concentrations were 71.8 +/- 9.8% and 13.6 +/- 9.3% for serum and 61.7 +/- 7.8% and 6.8 +/- 3.5% for brain extracellular fluid in the intermittent and continuously infused groups, respectively. Accordingly, the relative changes in vancomycin concentrations in brain extracellular fluid were closely associated with corresponding changes in serum concentrations (R2=0.94). Thus, continuous intravenous administration of vancomycin results in minimal serum and CNS tissue concentration changes as compared to traditional intermittent dosing methods and allows for more consistent vancomycin concentrations in the CNS.

A case of spontaneous methicillin-resistant Staphylococcus aureus meningitis in a health care worker

Meningitis caused by Staphylococcus aureus is an unusual illness that is often associated with bacteremia, contiguous infection and/or a post-neurosurgical state. Until recently, most cases were caused by methicillin-susceptible strains, but there are a few reports of methicillinresistant S aureus strains causing meningitis. A new case of meningitis caused by methicillin-resistant S aureus in a neonatal intensive care nurse who did not have bacteremia or neurosurgery is reported. The patient made a full recovery after treatment with vancomycin and rifampin.

Comparative analysis of acid sphingomyelinase distribution in the CNS of rats and mice following intracerebroventricular delivery

Niemann-Pick A (NPA) disease is a lysosomal storage disorder (LSD) caused by a deficiency in acid sphingomyelinase (ASM) activity. Previously, we reported that biochemical and functional abnormalities observed in ASM knockout (ASMKO) mice could be partially alleviated by intracerebroventricular (ICV) infusion of hASM. We now show that this route of delivery also results in widespread enzyme distribution throughout the rat brain and spinal cord. However, enzyme diffusion into CNS parenchyma did not occur in a linear dose-dependent fashion. Moreover, although the levels of hASM detected in the rat CNS were determined to be within the range shown to be therapeutic in ASMKO mice, the absolute amounts represented less than 1% of the total dose administered. Finally, our results also showed that similar levels of enzyme distribution are achieved across rodent species when the dose is normalized to CNS weight as opposed to whole body weight. Collectively, these data suggest that the efficacy observed following ICV delivery of hASM in ASMKO mice could be scaled to CNS of the rat.

Failure of vancomycin treatment for meningitis caused by vancomycin-susceptible Enterococcus faecium

This case report describes a nosocomial vancomycin-sensitive Enterococcus faecium meningitis with poor response to vancomycin. E. faecium infections continue to represent a therapeutic challenge in Europe, even in countries where vancomycin resistance is still rare. In the case of vancomycin-sensitive E. faecium meningitis, intravenous chloramphenicol should be considered as a treatment option.

Update in the diagnosis and management of central nervous system infections

Central nervous system (CNS) infections presenting to the emergency room include meningitis, encephalitis, brain and spinal epidural abscess, subdural empyema, and ventriculitis. These conditions often require admission to an intensive care unit (ICU) and are complications of ICU patients with neurologic injury, contributing significantly to morbidity and mortality. Reducing morbidity and mortality is critically dependent on rapid diagnosis and, perhaps more importantly, on the timely initiation of appropriate antimicrobial therapy. New insights into the role of inflammation and the immune response in CNS infections have contributed to development of new diagnostic strategies using markers of inflammation, and to the study of agents with focused immunomodulatory activity, which may lead to further adjunctive therapy in human disease.

Bacterial meningitis from Rothia mucilaginosa in patients with malignancy or undergoing hematopoietic stem cell transplantation

Opportunistic infections contribute to morbidity and mortality of patients undergoing hematopoietic stem cell transplantation and treatment for malignancies. Rothia mucilaginosa, a gram-positive bacterium, is responsible for rare, but often fatal meningitis in severely immunocompromised patients. We describe two cases of meningitis from discrete strains of R. mucilaginosa on our pediatric bone marrow transplant unit, summarize the published cases of R. mucilaginosa meningitis in oncology and stem cell transplant patients, and provide updated recommendations regarding the use of antibiotic therapy in this patient population.

Vancomycin-resistant enterococcal meningitis treated with intrathecal streptomycin

Enterococcal meningitis is a rare complication of neurosurgical procedures. We present a patient who developed vancomycin-resistant enterococcal ventriculitis - meningitis after a brain tumor resection and ventriculoperitoneal shunt placement, treated successfully with intrathecal streptomycin through bilateral cerebrospinal fluid drainage catheters in addition to systemic antibiotics. This is the first report of such treatment for this resistant organism.

Treatment of cerebrospinal fluid shunt infections in children using systemic and intraventricular antibiotic therapy in combination with externalization of the ventricular catheter: efficacy in 34 consecutively treated infections

OBJECT

There are no randomized studies comparing the efficacy of different antibiotic regimens for the treatment of cerebrospinal fluid (CSF) shunt infections, and in the studies that have been reported, efficacy data are limited. The aim of this study was therefore to report the authors' experience using a specific protocol for the management of shunt infections in children. Standard treatment included a two-stage procedure involving externalization of the ventricular catheter in combination with intraventricular and systemic administration of antibiotic medication followed by shunt replacement. Intraventricular treatment consisted of daily instillations of vancomycin or gentamicin with trough concentrations held at high levels of 7 to 17 mg/L for both antibiotic agents.

METHODS

During a 13-year study period, the authors treated 34 consecutive intraventricular shunt infections in 30 children. Infections with coagulase-negative staphylococci predominated, and Gram-negative bacterial infection occurred in five children. Ten of the children were initially treated with intravenous antibiotic therapy for at least 3 days, but this treatment did not sterilize the CSF. After externalization of the ventricular catheter, high-dose intraventricular treatment was given for a median of 8 days (range 3-17 days) before shunt replacement.

RESULTS

The CSF was found to be sterile (cultures were negative for bacteria) in one of three, seven of eight, 20 of 20, and six of six cases after 1, 2, 3, and more than 3 days' treatment, respectively. In no case was any subsequent culture positive after a negative result had been obtained. Clinical symptoms resolved in parallel with the sterilization of the CSF. There were no relapses or deaths during the 6-month follow-up period, and there have been none as of April 2007.

CONCLUSIONS

Despite the ventricular catheter being left in place and the short duration of therapy, the treatment regimen described by the authors resulted in quick sterilization of the CSF, a low relapse rate, and survival of all patients in this series.

Advances in the management of central nervous system infections in the ICU

This chapter focuses on early aggressive management of common infections of the central nervous system that require monitoring in an ICU setting. These include meningitis, encephalitis, brain and epidural abscess, subdural empyema and ventriculitis. It emphasizes priorities in evaluation and management due to increasing morbidity and mortality as a result of failure to appreciate non-specific symptoms or administer timely therapy. The emergence of organisms resistant to penicillin and cephalosporins has also further complicated the early management of bacterial meningitis. Current antimicrobial guidelines are provided along with discussion of new diagnostic and therapeutic strategies and controversial aspects of management.

Cure of ventriculitis and central nervous system shunt infection by Staphylococcus epidermidis with vancomycin by intraventricular injection in a liver transplant recipient

A 19-year-old female underwent orthotopic liver transplantation for acute hepatic failure because of fulminant Wilson's disease. Three months post transplantation she developed systemic fungal meningoencephalitis and obstructive hydrocephalus that required cerebrospinal fluid (CSF) shunting by a ventriculo-atrial shunt. Subsequently, she contracted Staphylococcus epidermidis bacteremia, ventriculitis, and shunt infection. Treatment with vancomycin either by conventional intravenous (i.v.) or continuous i.v. injection proved ineffective because of insufficient drug concentrations in the CSF. Eradication of S. epidermidis from CSF and cure of chronic ventriculitis and shunt infection was readily achieved by delivering vancomycin by intraventricular injection (5 mg/24 h) via an extraventricular drain together with continuous i.v. infusion (4 g/24 h) over a period of 18 days. This treatment was well tolerated and free of untoward side effects despite the patient's chronic immunosuppression subsequent to liver transplantation. Intraventricular injection of vancomycin is an effective and safe procedure to eradicate S. epidermidis from the central nervous system when i.v. vancomycin treatment fails.

Vancomycin disposition and penetration into ventricular fluid of the central nervous system following intravenous therapy in patients with cerebrospinal devices

OBJECTIVE/AIMS

To determine the cerebrospinal fluid concentrations and percent CNS penetration of intravenous vancomycin in patients with cerebrospinal devices at a pediatric institution.

METHODS

We performed a prospective evaluation of intravenous (IV) vancomycin in patients who received a single prophylactic dose of vancomycin (15-20 mg/, maximum dose 1 g) prior to insertion of a CNS shunt (group I) or a therapeutic regimen (a dose of 10-20 mg/kg every 6-12 h) for a documented/suspected shunt infection (group II). Ventricular cerebrospinal fluid (VCSF) samples were taken during the procedure in group I and multiple serum and VCSF samples were collected in group II. Pharmacokinetic parameters were calculated using a one-compartment model, and percent CNS penetration was estimated using area-under-the-curve methodology.

RESULTS

Group I: 21 VCSF samples were analyzed from 19 patients (mean age 7.2 +/- 6.4 years). Over 40% of samples failed to have detectable vancomycin concentrations (range 0-2 microg/ml). Group II: 6 patients (mean age 11 +/- 8.7 years) had VCSF concentrations ranging from nondetectable to 6.59 microg/ml (mean 2.48 +/- 0.52 microg/ml). Percent penetration ranged from 0.77 to 18%.

CONCLUSIONS

Single-dose, pre-operative vancomycin results in low VCSF vancomycin concentrations and repeated dosing in patients with documented/presumed device infections yields variable CNS penetration.

Persistent and intractable ventriculitis due to retained ventricular catheters

It is generally recommended that, in cases of difficulty in removing a ventricular catheter during a shunt revision, it is best left alone to avoid intraventricular haemorrhage. Retained ventricular catheters (RVCs) are usually safe, although in the presence of ventriculitis they may become colonized by organisms and become a source of persistent or recurrent infection. The authors present a case of persistent and intractable ventriculitis due to an old retained ventricular catheter. A 23-year-old female, who had a RVC and a functioning shunt, was admitted for a suspected blocked shunt. At surgery the shunt was found to be infected and external drainage was instituted. Over the next 4 months, she developed intractable and persistent staphylococcal ventriculitis, despite undergoing 10 further surgical procedures, and appropriate intravenous and intrathecal antibiotic therapy. She responded rapidly only after surgical removal of the old RVC via a craniotomy. The staphylococcus cultured from the RVC had an identical antibiogram to the organism responsible for the intractable ventriculitis. This case emphasizes the point that, although RVC are generally considered safe, removal becomes imperative in the presence of concurrent CSF infection that fails to respond quickly to intrathecal antibiotic therapy.

Group B streptococcal ventriculitis: a report of three cases and literature review

This report presents three cases of neonatal group B streptococcal ventriculitis and assesses seven others identified by a literature review. In contrast to the well described acute manifestations of group B streptococcal meningitis, disease onset tended to be insidious with four of seven cases presenting over a period of 1 to 6 weeks and six cases presenting with nonspecific signs and symptoms without fever. Persistent protein content elevation and low glucose level in the cerebrospinal fluid was observed, indicating chronic inflammation. All patients developed obstructive hydrocephalus requiring ventriculoperitoneal shunt placement. One child died, and six of nine survivors were left with significant neurologic deficits. Physicians should be aware of this indolent but serious manifestation of group B streptococcal infection.

Serial Cytokine Profiles in Shunt-Related Ventriculitis Treated with Intraventricular Vancomycin

BACKGROUND

A 1-month-old premature infant developed persistent shunt-related methicillin-resistant Staphylococcus aureus ventriculitis that was not responsive to parenteral therapy with vancomycin plus gentamicin (or rifampin).

METHODS

The infant was treated by intraventricular administration of vancomycin (5 days: 10 mg/day). In addition to standard testing of the cerebrospinal fluid (CSF), tumor necrosis factor alpha, interleukin-8 and interleukin-6 were serially measured.

RESULTS

Sterilization of the CSF was followed by a decline in the number of WBC and proinflammatory cytokines in the CSF.

CONCLUSION

Intraventricular administration of antibiotics may be considered if ventriculitis is refractory to systemic antimicrobial therapy. Serial measurements of inflammatory cytokines in the CSF may provide an additional diagnostic tool to monitor the outcome of therapy.

Pharmacokinetics of fluconazole in the cerebrospinal fluid of children with hydrocephalus

BACKGROUND

The aim of this study was to examine the pharmacokinetics of fluconazole in the CSF of children with hydrocephalus during CNS infection treatment after intravenous and/or intraventricular drug administration. Direct fluconazole administration into the ventricular CSF of patients to treat serious CNS infections is an aggressive therapy, and data on the pharmacokinetics of fluconazole in CSF are limited.

METHODS

A method of fluconazole quantification in CSF by solid-phase extraction (SPE)-high-performance liquid chromatography (HPLC) was developed to conduct pharmacokinetic studies. The population of patients included 2 children with hydrocephalus. Fluconazole was administered intravenously at average multiple doses of 12.5 mg/kg/24 h and intraventricularly at doses of 4, 5 and 7.5 mg/24 h, and 7.5 and 10 mg/12 h. The CSF samples were taken 2-24 h after administration of fluconazole. The concentrations of fluconazole in CSF specimens were assessed, and after pharmacokinetic studies the fluconazole dosage was modified.

RESULTS

The method of fluconazole determination in CSF using the SPE-HPLC method is specific, precise and accurate. After intravenous fluconazole administration, the concentration of this antifungal drug was not detected in the ventricular CSF. The pharmacokinetic parameters determined after intraventricular fluconazole administration were: steady-state peak CSF fluconazole concentration (19.54 +/- 5.63 mg/l); trough CSF fluconazole concentration (0.0-0.3 mg/l); elimination rate constant (0.4654 +/- 0.2097 h(-1)), and half-life (1.84 +/- 0.93 h).

CONCLUSIONS

The authors developed a method to determine fluconazole in CSF by SPE-HPLC. After intravenous fluconazole administration, the drug was not detected in the examined CSF samples. The intraventricular multidose pharmacokinetic data suggest the necessity of fluconazole monitoring in children with hydrocephalus during the treatment of shunt infection.

Linezolid for the treatment of a heteroresistant Staphylococcus aureus shunt infection

The emergence of multidrug-resistant bacteria as the cause of ventriculoperitoneal shunt infections is a disconcerting phenomenon that often requires the use of alternative antimicrobials due to resistance against commonly used agents. The following is a case report describing the successful treatment of a ventriculoperitoneal shunt infection caused by a heteroresistant strain of Staphylococcus aureus with linezolid. Linezolid may have utility in treating pediatric CNS infections due to its tolerability, excellent blood-brain barrier penetration, and activity against multiple resistant Gram-positive organisms such as S. aureus, vancomycin-resistant Enterococcus faecium and Streptococcus pneumoniae.

Therapeutic vancomycin monitoring in children with hydrocephalus during treatment of shunt infections

BACKGROUND

The successful treatment of shunt infections in children with hydrocephalus is still an important problem. Diagnosis of shunt colonization is often very difficult. To treat serious central nervous system (CNS) infections, intraventricular therapy with antibiotics is necessary to reach adequate cerebrospinal fluid (CSF) concentrations and eradicate the infection. For optimal management of shunt infections the concentration of administered antibiotics in CSF should be measured. The antibiotic dosing could be modified in the individual patient after pharmacokinetic studies.

METHODS

In our studies, vancomycin was applied to 10 children with hydrocephalus (including 6 with a myelomeningocele) for therapeutic purposes in shunt infections. The drug was administered IV and/or intraventricularly. During treatment the concentration of vancomycin in CSF was determined by fluorescence polarization immunoassay (FPIA) method.

RESULTS

Considerable differences in vancomycin concentrations after the same intraventricular antibiotic administration were observed depending on the patient. The vancomycin levels determined at study state were often much higher than the therapeutic recommended range, and the biologic half-life period (T(1/2)) of vancomycin in cerebrospinal fluid after intraventricular administration was prolonged.

CONCLUSIONS

The results of our studies give information about the pharmacokinetics of vancomycin in CSF in a group of children with hydrocephalus after intraventricular administration of the drug. In our investigation, the administration of doses smaller than 5 mg/24 hours is appropriate when the removed volume of CSF will be 20 to 30 mL/24 hours.

Treatment of staphylococcal ventriculitis associated with external cerebrospinal fluid drains: a prospective randomized trial of intravenous compared with intraventricular vancomycin therapy

OBJECT

Staphylococcal ventriculitis may be a complication in temporary external ventricular drains (EVDs). The limited penetration of vancomycin into the cerebrospinal fluid (CSF) is well known; the pharmacodynamics and efficacy of systemically compared with intraventricularly administered vancomycin is examined in this prospective study.

METHODS

Ten patients in whom EVDs were implanted to treat intracranial hemorrhage and who were suffering from drain-associated ventriculitis were randomized into two treatment groups. Five of these patients (median age 47 years) were treated with 2 g/day vancomycin administered intravenously (four infusions/day, Group 1), and the other five(median age 49 years) received 10 mg vancomycin intraventricularly once daily (Group 2). Vancomycin levels were measured in serum and CSF six times a day. The maximum vancomycin level in CSF was 1.73 +/- 0.4 micro/ml in Group 1 and 565.58 +/- 168.71 microg/ml 1 hour after vancomycin application in Group 2 (mean +/- standard deviation). Vancomycin levels above the recommended trough level of 5 microg/ml in CSF were never reached in Group 1, whereas in Group 2 they below the trough level (3.74 +/- 0.66 microg/ml) only at 21 hours after intraventricular vancomycin application. The vancomycin level in the serum was constant within therapeutic levels in Group 1, whereas in Group 2 in most instances vancomycin was almost below a measurable concentration. In both groups bacteriologically and laboratory-confirmed CSF clearance could be obtained.

CONCLUSIONS

Intraventricular vancomycin application is a safe and efficacious treatment modality in drain-associated ventriculitis, with much higher vancomycin levels being achieved in the ventricular CSF than by intravenous administration.

Linezolid for the treatment of central nervous system infections in neurosurgical patients

We report our experience with linezolid in the treatment of 5 patients with central nervous system infections subsequent to neurosurgical interventions. In all cases, initial antimicrobial treatment regimens, including a glycopeptide, either failed or were associated with significant adverse events. The good clinical outcome and the absence of significant side-effects associated with linezolid suggest that it may be an attractive alternative for the treatment of central nervous system infections, particularly in settings characterized by a high incidence of multiresistant Gram-positive pathogens.

Sensorineural hearing loss associated with intrathecal vancomycin

OBJECTIVE

To report a case of nonreversible bilateral sensorineural hearing loss resulting from administration of intrathecal vancomycin.

CASE SUMMARY

A 63-year-old white man with newly diagnosed pre-B-cell acute lymphocytic leukemia developed Corynebacterium jeikeium meningitis associated with an Ommaya reservoir. The patient was treated with intravenous vancomycin for several days without symptomatic improvement, and intrathecal vancomycin was added to the treatment regimen. Difficulty in the patient's hearing was noted after the first intrathecal dose and he experienced complete hearing loss after the second intrathecal dose. An audiogram was performed and the patient was diagnosed with cranial nerve VIII bilateral sensorineural hearing loss. The Ommaya reservoir was removed and the patient was successfully treated with linezolid.

DISCUSSION

Ototoxicity with intravenous vancomycin has been documented in multiple case reports, but this adverse effect has not been reported with intrathecal vancomycin. Cerebrospinal fluid vancomycin concentrations were not measured in our patient, but there was 1 documented occurrence of supratherapeutic serum vancomycin concentrations. Other drug-related causes of ototoxicity were evaluated and intrathecal vancomycin-induced ototoxicity was considered to be possible according to the Naranjo probability scale.

CONCLUSIONS

The strong temporal relationship that was seen in this case suggests the possibility of an association between administration of intrathecal vancomycin and hearing loss. Healthcare providers should consider the potential for this adverse reaction with the intrathecal route of vancomycin administration.

Successful treatment of meningoencephalitis caused by methicillin-resistant Staphylococcus aureus with intrathecal vancomycin in an allogeneic peripheral blood stem cell transplant recipient

Methicillin-resistant Staphylococcus aureus (MRSA) is a common infectious pathogen during stem cell trans-plantation. We report a case of meningoencephalitis with multiple abscess formation caused by MRSA, which occurred in a 4-year-old boy soon after allogeneic peripheral blood stem cell transplantation. We successfully cured the infection with a combination of intravenous and intrathecal vancomycin.

Reduction of cerebral infarction using the third circulation

OBJECTIVE

To ascertain whether ventriculosubarachnoid perfusion of the brain with an oxygen-carrying nutrient emulsion affects the volume of infarction in animals with permanent middle cerebral artery occlusion.

DESIGN

Prospective, randomized, controlled trial.

SETTING

An animal laboratory in a university setting.

SUBJECTS

Twenty-eight closed colony adult cats weighing between 3.5 and 4.5 kg.

INTERVENTIONS

Cats were assigned randomly into one of three groups: untreated surgical controls, artificial cerebrospinal fluid (ACSF) perfused, or oxygenated fluorochemical (t-bis perfluorobutylethylene; F44E) nutrient emulsion (OFNE) perfused. The formulation used in this study was developed for clinical use and is currently being used in a phase 1 clinical trial in patients with severe ischemic stroke. Focal cerebral ischemia was induced by permanently clipping the middle cerebral artery via the retro-orbital approach. Treatment was initiated 90 mins postocclusion and continued for 18 hrs. Animals were killed 1 hr after the termination of perfusion, the brains were sectioned and stained with 2,3,5-triphenyltetrazolium chloride, and the infarct area was determined with a computer digitizer.

MEASUREMENTS AND MAIN RESULTS

There was a significant difference in cerebral infarct volume in the OFNE-perfused animals compared with the other groups ( p<or=.015). Intracranial pressure was significantly reduced in the OFNE-perfused group relative to the surgical control group at 18 hrs ( P<or=.05). Overall, infarct volume correlated with intracranial pressure measured at the end of the treatment period (Spearman rank order, p<.001).

CONCLUSIONS

Fluorochemical emulsion delivery of oxygen and nutrients directly to the brain by means of ventriculocisternal perfusion is a viable treatment alternative for cerebral ischemia. In addition, this technique may control elevations in intracranial pressure following stroke.

Central nervous system infections: a critical care approach

Central nervous system (CNS) infections are diverse. CNS infections can cause significant morbidity and mortality and are markedly different from systemic infections. The closed anatomic space of the CNS, its immunologic isolation from the rest of the body, and the often nonspecific nature of the key manifestations present a challenge to the clinician. Early recognition and aggressive management are essential to patient recovery and prevention of long-term neurologic sequelae. This review discusses the major types of CNS infections and focuses on critical care management, with emphasis on current epidemiologic trends.

Managing Intractable Pain with an Intrathecal Catheter and Injection Port: Technique and Guidelines

The objective of our study was to describe an effective technique for the management of chronic intractable pain in patients with intermediate life expectancy or as a long-term screening device prior to implantable pump therapy. In the study, an InDura™ intraspinal catheter is connected to a BardPort™, which is accessed transdermally. We describe our surgical technique, recommended dosage calculations, cost comparison to an implantable infusion pump, and our experience with 13 cases. In our series of 13 patients, there was one seroma and one dural leak. There were no infections, and all were functioning well in the 12 cancer patients until their deaths. One case was converted to an implantable pump. There were no malfunctions or infections of the intrathecal infusion system in the 12 cancer patients. This intrathecal drug infusion system should be considered in the treatment armamentarium for chronic intractable pain and cancer pain.

The penetration of anti-infectives into the central nervous system

The blood-brain barrier, blood-cerebrospinal fluid (CSF) barrier, and meninges are a complex and difficult-to-study system charged with protecting the central nervous system (CNS) from toxins, including drugs. Current estimates of CNS drug exposure are limited to CSF to blood ratios, of which area-under-the curve (AUC) estimates provide the most robust measure of drug exposure. Different classes of drugs and individual drugs within classes have different CNS penetration potential that is dependent upon a variety of biologic and pharmacologic factors. Clinical data (AUC and point ratios) regarding the penetration of several anti-infective agents used for the treatment of CNS infections are provided in this article.

Laboratory guidelines for monitoring of antimicrobial drugs

Few antimicrobial drugs meet the requirements for therapeutic drug monitoring. Those that are monitored include the aminoglycosides (gentamicin, tobramycin, and amikacin), chloramphenicol, and in some cases, vancomycin. For these drugs, there is evidence of a relationship between serum concentration, efficacy, and/or the incidence of adverse or toxic events. Monitoring begins with the appropriate timing of collection and continues through the analytical process to the integration of all data used to guide the clinician’s next decision.

Pharmacokinetics of drugs used in critically ill adults

Critically ill patients exhibit a range of organ dysfunctions and often require treatment with a variety of drugs including sedatives, analgesics, neuromuscular blockers, antimicrobials, inotropes and gastric acid suppressants. Understanding how organ dysfunction can alter the pharmacokinetics of drugs is a vital aspect of therapy in this patient group. Many drugs will need to be given intravenously because of gastrointestinal failure. For those occasions on which the oral route is possible, bioavailability may be altered by hypomotility, changes in gastrointestinal pH and enteral feeding. Hepatic and renal dysfunction are the primary determinants of drug clearance, and hence of steady-state drug concentrations, and of efficacy and toxicity in the individual patient. Oxidative metabolism is the main clearance mechanism for many drugs and there is increasing recognition of the importance of decreased activity of the hepatic cytochrome P450 system in critically ill patients. Renal failure is equally important with both filtration and secretion clearance mechanisms being required for the removal of parent drugs and their active metabolites. Changes in the steady-state volume of distribution are often secondary to renal failure and may lower the effective drug concentrations in the body. Failure of the central nervous system, muscle, the endothelial system and endocrine system may also affect the pharmacokinetics of specific drugs. Time-dependency of alterations in pharmacokinetic parameters is well documented for some drugs. Understanding the underlying pathophysiology in the critically ill and applying pharmacokinetic principles in selection of drug and dose regimen is, therefore, crucial to optimising the pharmacodynamic response and outcome.

Once-daily gentamicin therapy for experimental Escherichia coli meningitis

In vitro and in vivo studies have demonstrated that the bacteriologic efficacy of once-daily aminoglycoside therapy is equivalent to that achieved with conventional multiple daily dosing. The impact of once-daily dosing for meningitis has not been studied. Using the well-characterized rabbit meningitis model, we compared two regimens of the same daily dosage of gentamicin given either once or in three divided doses for 24 or 72 h. The initial 1 h mean cerebrospinal fluid (CSF) gentamicin concentration for animals receiving a single dose (2.9 +/- 1.7 micrograms/ml) was threefold higher than that for the animals receiving multiple doses. The rate of bacterial killing in the first 8 h of treatment was significantly greater for the animals with higher concentrations in their CSF (-0.21 +/- 0.19 versus -0.03 +/- 0.22 log10 CFU/ml/h), suggesting concentration-dependent killing. By 24h, the mean reduction in bacterial titers was similar for the two regimens. In animals treated for 72 h, no differences in bactericidal activity was noted for 24, 48, or 72 h. Gentamicin at two different dosages was administered intracisternally to a separate set of animals to achieve considerably higher CSF gentamicin concentrations. In these animals, the rate of bacterial clearance in the first 8 h (0.52 +/- 0.15 and 0.58 +/- 0.15 log10 CFU/ml/h for the lower and higher dosages, respectively) was significantly greater than that in animals treated intravenously. In conclusion, there is evidence of concentration-dependent killing with gentamicin early in treatment for experimental E. coli meningitis, and once-daily dosing therapy appears to be at least as effective as multiple-dose therapy in reducing bacterial counts in CSF.

Drug monitoring in nonconventional biological fluids and matrices

Determination of the concentration of drugs and metabolites in biological fluids or matrices other than blood or urine (most commonly used in laboratory testing) may be of interest in certain areas of drug concentration monitoring. Saliva is the only fluid which can be used successfully as a substitute for blood in therapeutic drug monitoring, while an individual's past history of medication, compliance and drug abuse, can be obtained from drug analysis of the hair or nails. Drug concentrations in the bile and faeces can account for excretion of drugs and metabolites other than by the renal route. Furthermore, it is important that certain matrices (tears, nails, cerebrospinal fluid, bronchial secretions, peritoneal fluid and interstitial fluid) are analysed, as these may reveal the presence of a drug at the site of action; others (fetal blood, amniotic fluid and breast milk) are useful for determining fetal and perinatal exposure to drugs. Finally, drug monitoring in fluids such as cervical mucus and seminal fluid can be associated with morpho-physiological modifications and genotoxic effects. Drug concentration measurement in nonconventional matrices and fluids, although sometimes expensive and difficult to carry out, should therefore be considered for inclusion in studies of the pharmacokinetics and pharmacodynamics of new drugs.