Comparative penetration of six antibiotics into the cerebrospinal fluid of rabbits with experimental staphylococcal meningitis

Cefazolin in the treatment of central nervous system infections: A narrative review and recommendation

Infections of the central nervous system (CNS) are complex to treat and associated with significant morbidity and mortality. Historically, antistaphylococcal penicillins such as nafcillin were recommended for the treatment of methicillin-susceptible staphylococcal CNS infections. However, the use of antistaphylococcal penicillins presents challenges, such as frequent dosing administration and adverse events with protracted use. This narrative reviews available clinical and pharmacokinetic/pharmacodynamic (PK/PD) data for cefazolin in CNS infections and produces a recommendation for use. Based on the limited available evidence analyzed, dose optimized cefazolin is likely a safe and effective alternative to antistaphylococcal penicillins for a variety of CNS infections due to methicillin-susceptible Staphylococcus aureus. Given the site of infection and wide therapeutic index of cefazolin, practitioners may consider dosing cefazolin regimens of 2 g IV every 6 h or a continuous infusion of 8-10 g daily instead of 2 g IV every 8 h to optimize PK/PD properties.

Flucloxacillin does not achieve therapeutic cerebrospinal fluid levels against meticillin-sensitive Staphylococcus aureus in adults: A case report and review of the literature

It is uncertain whether flucloxacillin achieves therapeutic concentrations against meticillin-sensitive Staphylococcus aureus (MSSA) in cerebrospinal fluid (CSF). In this study, plasma and CSF concentrations of flucloxacillin and vancomycin in an adult patient were compared. Unlike vancomycin, the flucloxacillin CSF level was not therapeutic. Flucloxacillin monotherapy should be used with caution for MSSA central nervous system infection in adults.

Levels of vancomycin in the cerebral interstitial fluid after severe head injury

OBJECTIVE

To evaluate the concentrations of vancomycin in the cerebral interstitial fluid after intravenous administration by multiple boli.

DESIGN

Prospective non randomized study

SETTING

University hospital general ICU.

PATIENTS

Four patients undergone to craniotomy for evacuation of cerebral posttraumatic hemorrhage, who developed pneumonia 4-7 days from the injury

METHODS

Two microdialysis catheters were placed in each patient: one in the edematous brain surrounding the focal lesion and one in the subcutaneous tissue of abdomen. Levels of vancomycin were measured in serum and in the microdialysates samples.

RESULTS

Plasmatic concentration of 10-15 microg/ml in the trough level was obtained after four administrations of vancomycin. Levels of vancomycin in the subcutaneous tissue was above minimum inhibitory concentrations in all patients after the second administration. Mean serum/brain ratio was 8%. Cerebral interstitial concentration of vancomycin was never above minimum inhibitory concentrations; its maximum value was 1.2 microg/ml.

CONCLUSIONS

In edematous brain close to a posttraumatic hemorrhage the levels of vancomycin do not differ from that in healthy subjects. At these plasmatic concentrations cerebral interstitial levels of vancomycin were insufficient while subcutaneous interstitial levels were effective for clinical use.

Role of glycopeptides in the treatment of septic complications after cardiac surgery

Agents like Staphylococcus epidermidis and Staphylococcus aureus are common agents in both early and late prosthetic valve endocarditis (PVE). Streptococci, especially vividans and enterococci are more apt to occur late. Diphtheroids and gram-negative bacteria are also frequent in early and late PVE. Fungi are found at a frequency of 5 to 8% and a variety of unusual organisms are found in individual case reports. Treatment is based on parenteral therapy with a bactericidal agent that can achieve trough serum levels in excess of 8-10 X MICs of the infecting organisms. Initially the antibiotic selection should be active against the most common isolates. Because most S. epidermidis are beta-lactam-resistant, vancomcyin must be part of the initial empiric regimen. Vancomycin should be combined with rifampin or an aminoglycoside (usually gentamicin) or both. When there is a high level of resistance to aminoglycoside, vancomycin may be used alone until susceptibility data are available and then rifampin can be given together with an aminoglycoside or a quinolone to which the organism is susceptible. The aminoglycoside should be given for a maximum of 2 weeks, to avoid nephrotoxicity, and vancomycin for 6 weeks. Surgery is required in case of major emboli, hemodynamic decompensation, and uncontrolled infection. The presence of bacteremia for more than 1 week may warrant surgical intervention but, if the patient appears to be well and without emboli or hemodynamic problems, serum levels of antibiotic, particularly vancomycin, should be evaluated. Dosage regimen should be modified to achieve trough levels of vancomycin between 15 to 20 microg/ml. Use of vancomycin by continuous infusion may be considered with a targeted blood concentration of 15 to 20 microg/ml.

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.

[Glycopeptides]

OBJECTIVES

To review pharmacology, pharmacokinetic and therapeutic use of glycopeptides in intensive care units.

DATA SOURCES

Extraction from Medline database of French and English articles on glycopeptides and search along with major review articles.

DATA SELECTION

The collected articles were reviewed and selected according to their quality and originality. The more recent data were selected.

DATA SYNTHESIS

Glycopeptides are bactericidal antibiotics which are only active against Gram positive species acting by inhibiting peptidoglycan synthesis. They had been in clinical use for almost 30 years without high-level resistance underlining. For ten years, there have been disturbing reports of first, resistance to vancomycin in enterococcal species and more recently in strains of Staphylococcus aureus by complex and large mechanisms of action. This new resistances may lead to a therapeutic impasse and a fatal issue for infected patients. The only response to this situation is the respect of prescription rules and the careful use of antibiotics.

CONCLUSION

Considering their spectrum, glycopeptides are an antibiotic family which importance is fundamental to treat infected patients of intensive care units. Staff members of intensive care units are responsible for their good use.

Vancomycin: a review

This article reviewed the past experience and updated the present data on vancomycin. In recent years, with the release of more purified preparations of vancomycin and new clinical problems facing the clinician (that is, increasing prevalence of serious methicillin-resistant staphylococcal infections; use of hemodialysis and CAPD; widespread use of prosthetic devices; aggressive chemotherapy), the indication for vancomycin use has increased dramatically. More information is needed on the distribution of vancomycin in body tissues and the incidence and mechanisms of toxicity. Close surveillance of in vitro susceptibility patterns will be necessary as widespread use of vancomycin continues to increase.

Rationale for optimal dosing of beta-lactam antibiotics in therapy for bacterial meningitis

This review considers the five major principles governing optimal dosing of beta-lactam antibiotics in therapy for bacterial meningitis: off the entry of passage of antibiotics into CSF, (2) the antimicrobial activity of beta-lactams within the purulent CSF in vivo, (3) the bactericidal activity within the CSF, (4) the route and mode of drug administration together with the postantibiotic effect, and (5) the duration of therapy. Special attention is paid to the third principle, bactericidal activity within the CSF, employing the model of the newer, third-generation cephalosporins used in the treatment of meningitis caused by gram-negative aerobic bacilli.

Pathogenesis of bacterial meningitis: contributions by experimental models in rabbits

Rabbits models of bacterial meningitis have contributed substantially to our understanding of the disease, although the technical characteristics of these models only allow the study of specific aspects of the disease. Bacterial multiplication in the subarachnoidal space is not substantially influenced by host defense mechanisms, mainly because of the lack of sufficient amounts of specific antibodies and functional complement in infected CSF. The multiplying bacteria induce profound changes in the blood-brain barrier, an influx of serum proteins into the CSF and the invasion of polymorphonuclear leukocytes at the site of the infection. The presence of polymorphonuclear leukocytes in CSF not only appears to be of limited value in combating the infection, but also seems to produce deleterious effects on the central nervous system. Components of the leukocytes, such as unsaturated fatty acids, arachidonic metabolites and free oxygen radicals, may contribute to the profound hydrodynamic, structural and metabolic changes that are currently under study in experimental models of the disease. A better understanding of the pathophysiology of bacterial meningitis may allow us to design more effective therapeutic strategies and improve the outcome of this disease.

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.