Linezolid is an antibiotic used for the treatment of serious infections caused by Gram positive bacteria that are resistant to other antibiotics. Linezolid is active against most Gram-positive bacteria that cause disease, including streptococci, vancomycin-resistant enterococci (VRE), and methicillin resistant Staphylococcus aureus (MRSA).
The main uses are infections of the skin and pneumonia although it may be use for a variety of other infections.
When administered for short periods, linezolid is a relatively safe antibiotic. It can be used in people of all ages and in people with liver disease or poor kidney function. Common adverse effects of short-term use include headache, diarrhea, and nausea. Long-term use, however, has been associated with serious adverse effects such as bone marrow suppression and low platelet counts, particularly when used for more than two weeks. If used for longer periods still, it may cause sometimes irreversible chemotherapy-induced peripheral neuropathy and optic nerve damage, and lactic acidosis (a buildup of lactic acid in the body), all most likely due to mitochondrial toxicity.
As a protein synthesis inhibitor, it stops the growth of bacteria by disrupting their production of proteins, that is, it is a bacteriostatic agent, not bacteriocidal. Although many antibiotics work this way, the exact mechanism of action of linezolid appears to be unique in that it blocks the initiation of protein production, and not one of the later steps.
Bacterial resistance to linezolid has remained very low since it was first detected in 1999, although it may be increasing. It is a member of the oxazolidinone class of drugs.
Linezolid was discovered in the 1990s by a team at Pharmacia and Upjohn Company and first approved for use in 2000. It is on the World Health Organization’s List of Essential Medicines, the most important medications needed in a basic health system.
Linezolid costs approximately US$100 per tablet in the United States. Nonetheless, it appears to be more cost-effective than generic alternatives such as vancomycin, mostly because of the possibility of switching from intravenous to oral administration as soon as patients are stable enough, without the need for dose adjustments.
In animal studies of meningitis caused by Streptococcus pneumoniae, linezolid was found to penetrate well into cerebrospinal fluid, but its effectiveness was inferior to that of other antibiotics.
There does not appear to be enough high-quality evidence to support the routine use of linezolid to treat bacterial meningitis. Nonetheless, it has been used successfully in many cases of central nervous system infection—including meningitis—caused by susceptible bacteria, and has also been suggested as a reasonable choice for this indication when treatment options are limited or when other antibiotics have failed.
The guidelines of the Infectious Diseases Society of America recommend linezolid as the first-line drug of choice for VRE meningitis, and as an alternative to vancomycin for MRSA meningitis.
Linezolid appears superior to vancomycin in treating community-acquired MRSA infections of the central nervous system, although very few cases of such infections have been published (as of 2009).
Effectiveness in Neurosurgery
Evidence for the effectiveness of linezolid in neurosurgical infections (NSIs) is growing. The comfortable oral dosage and tolerance of linezolid opens the possibility for sequential antimicrobial treatment (SAT) in stable patients after a period of intravenous treatment 1).
Relevant studies were identified through searches of the PubMed, Current Contents, and Cochrane databases (publications archived until October 2006).
Case reports, case series, prospective and retrospective studies, and randomized controlled trials were eligible for inclusion in our review if they evaluated the effectiveness and safety of linezolid for the treatment of patients with CNS infections.
In 18 (42.9%) of the 42 relevant cases identified, patients had undergone neurosurgical operations and/or had prosthetic devices. Meningitis was the most common CNS infection, accounting for 20 (47.6%) cases. Other CNS infections included brain abscesses (14; 33.3%), ventriculitis (5; 11.9%), and ventriculo-peritoneal shunt infection (3; 7.1%). In the 39 patients in whom the responsible pathogen was isolated, those predominantly responsible for the CNS infections were: penicillin-nonsusceptible Streptococcus pneumoniae (7; 17.9%), vancomycin-resistant enterococci (6; 15.4%), Nocardia spp. (5; 12.8%), methicillin-resistant Staphylococcus epidermidis (4; 10.3%), and methicillin-resistant Staphylococcus aureus (3; 7.7%). Of the 42 patients who received linezolid for the treatment of CNS infections, 38 (90.5%) were either cured or showed clinical improvement of the infection. The mean duration of follow-up was 7.2 months; no recurrent CNS infection was reported.
The limited published data suggest that linezolid may be considered for the treatment of patients with CNS infections in cases of failure of previously administered treatment or limited available options 2).
To evaluate the efficacy and safety of SAT with oral linezolid in patients with NSI and to analyse the cost implications, an observational, non-comparative, prospective cohort study was conducted on clinically stable consecutive adult patients at the Neurosurgical Service. Following intravenous treatment, patients were discharged with SAT with oral linezolid.
A total of 77 patients were included. The most common NSIs were: 41 surgical wound infections, 20 subdural empyemas, 18 epidural abscesses, and 16 brain abscesses. Forty-four percent of patients presented two or more concomitant NSIs. Aetiological agents commonly isolated were: Propionibacterium acnes (36 %), Staphylococcus aureus (23 %), Staphylococcus epidermidis (21 %) and Streptococcus spp. (13 %). The median duration of the SAT was 15 days (range, 3-42). The SAT was interrupted in five cases due to adverse events. The remainder of the patients were cured at the end of the SAT. A total of 1,163 days of hospitalisation were saved. An overall cost reduction of €516,188 was attributed to the SAT. Eight patients with device infections did not require removal of the device, with an additional cost reduction of €190,595. The mean cost saving per patient was €9,179.
SAT with linezolid was safe and effective for the treatment of NSI. SAT reduces hospitalisation times, which means significant savings of health and economic resources 3).