The impact of methicillin-resistant Staphylococcus aureus in a neurosurgical unit: a growing problem

Epidemiology and clinical relevance of Staphylococcus aureus intestinal carriage: a systematic review and meta-analysis

INTRODUCTION

Recent data highlight the importance of screening more than one site for improving the detection of S. aureus colonization. Intestinal carriage is frequently under-investigated and its clinical impact ought to be defined a better way. Areas covered: This review and meta-analysis provide an updated overview of prevalence, characteristics and clinical significance of S. aureus intestinal carriage in different populations, both for methicillin-susceptible and -resistant S. aureus strains. Expert commentary: Intestinal S. aureus carriage is documented with higher prevalence in children and in patients with S. aureus skin and soft tissue infections. This site of colonization was shown to be associated with a high risk of dissemination in the environment and with S. aureus infection. Intestinal carriage is frequently retrieved in nasal carriers, reflecting probably an association with a high bacterial load. Exclusive intestinal carriage present in one third of intestinal carriers can be associated with infection. Comparative genotyping analysis of different strains from nasal and extra-nasal sites of carriage, including the intestinal ones, in the same individuals, would allow a better comprehension of the pathophysiology of S. aureus endogenous infection. It could also permit to improve the prevention of these infections by decolonization of sites implicated in infection genesis.

[Spinal column: implants and revisions]

Non-fusion spinal implants are designed to reduce the commonly occurring risks and complications of spinal fusion surgery, e.g. long duration of surgery, high blood loss, screw loosening and adjacent segment disease, by dynamic or movement preserving approaches. This principle could be shown for interspinous spacers, cervical and lumbar total disc replacement and dynamic stabilization; however, due to the continuing high rate of revision surgery, the indications for surgery require as much attention and evidence as comparative data on the surgical technique itself.

A 5-Year Epidemiological Study of Nosocomial Bloodstream Infections in a Neurosurgery Department

The characteristics of nosocomial bloodstream infections (BSIs) in a neurosurgical department were studied over a 5-year period. The rate of nosocomial BSI was 3.0%. Gram-negative bacteria were the most commonly isolated pathogens (65.9% of isolates). For all the pathogens isolated, the rate of resistance to commonly used antimicrobial agents was high. Of the 101 patients with nosocomial BSI, 50 (49.5%) died during their stay at the Department of Neurosurgery. At the same time, overall mortality rate among neurosurgical inpatients without nosocomial BSI was 5.4% (ie, 175 of 3,216 patients died).

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.

Pharmacokinetics of single-dose daptomycin in patients with suspected or confirmed neurological infections

There are currently few or no published data on the amount of cerebrospinal fluid (CSF) penetration of daptomycin in patients with suspected or documented neurosurgical infections. We conducted a prospective study, assessing the pharmacokinetics and CSF penetration of a single intravenous daptomycin dose administered at 10 mg/kg, based on total body weight (TBW), in six neurosurgical patients with indwelling external CSF shunts with suspected or documented meningitis or ventriculitis. Each patient had four blood and CSF samples drawn simultaneously at specific times after the end of infusion: 30 min, 6 h, 12 h, and 24 h. Pharmacokinetic parameters of daptomycin in serum were calculated using standard noncompartmental methods, and daptomycin was assayed using high-performance liquid chromatography (for serum) or liquid chromatography with mass spectrometry (for CSF). The mean (± standard deviation [SD]) maximum measured daptomycin concentrations were 93.7 ± 17.3 mg/liter in serum at 0.5 h postinfusion and 0.461 ± 0.51 mg/liter in CSF at 6 h postinfusion. The mean (± SD) daptomycin minimum concentrations were 13.8 ± 4.8 mg/liter in serum at 24 h postinfusion and 0.126 ± 0.12 mg/liter in CSF at 0.5 h postinfusion. The mean daptomycin penetration, determined by the area under the concentration-time curve in CSF (AUC(CSF))/(AUC(serum) ratio), was 0.8%. Corrected for protein binding, the overall CSF penetration was 11.5%. Additional pharmacokinetic studies evaluating multiple and/or higher dosages of daptomycin are necessary in human subjects to better characterize the CSF penetration of daptomycin in neurosurgical patients.

Treatment of infections of the spine

Spinal infection may involve the vertebrae, the intervertebral discs, and the adjacent intraspinal and paraspinal soft tissues. It often starts with subtle and insidious clinical signs and symptoms and may development to a debilitating and even life threatening disease. Spinal infections occur with increasing incidence and are nowadays a disease of everyday's practice for physicians treating spinal disorders. Traditionally, conservative treatment consisting of antibiosis and immobilisation is considered the first tier therapy. However, due to a considerably high rate of vertebral column instability or neurological impairment caused by the infected tissue, comprehensive experience with surgical measures have been acquired over the last decades. Thanks to tremendous improvements of surgical implants and techniques, surgical treatment has already begun to challenge conservative treatment to eventually become the first tier therapy for spinal infections in the future. This review seeks to give an overview of epidemiology, pathogenesis, diagnostic evaluation, and current nonsurgical and surgical therapy of spinal infections on the basis of the existing literature, which consists largely of retrospectively acquired data of single-centre experience with sample sizes of less than 100 patients treated with individually defined indications and treatment algorithms, and followed with various outcome parameters.

Perioperative management of neurosurgical patients with methicillin-resistant Staphylococcus aureus

Object

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has posed a challenge in the treatment of neurosurgical patients. The authors investigated the impact of MRSA colonization and infection in the neurosurgical population at a community-based, tertiary care referral center.

Methods

Hospitalized patients under the care of the Kaiser Permanente inpatient neurosurgery service were prospectively entered into a database. In Phase I of the study, 492 consecutive patients were followed. Per hospital policy, the 260 patients from this group who were admitted to the intensive care unit (ICU) underwent screening for MRSA based on nasal swab cultures and a review of their medical history for prior MRSA infections. These patients were designated as either MRSA positive (17 patients, 6.5% of screened patients) or MRSA negative (243 patients). The 232 patients admitted to non-ICU nursing units did not undergo MRSA screening and were designated as unscreened. In Phase II of the study, the authors reviewed 1005 neurosurgical admissions and completed a detailed chart review in 62 MRSA-positive patients (6.2%). Eleven patients received nonoperative treatment. Five patients presented with community-acquired neurosurgical infections, and the causative organism was MRSA in 3 cases. Forty-six patients underwent 55 procedures, and the authors reviewed their perioperative management.

Results

In Phase I of the study, the authors found that for the MRSA-positive, MRSA-negative, and unscreened groups, the rates of postoperative neurosurgical wound infections caused by all pathogens were 23.5, 4.1, and 1.3%, respectively. For MRSA wound infections, the rates were 23.5, 0.8, and 0%, respectively. In Phase II, patients with MRSA were noted to have the following clinical features: male sex in 63%, a malignancy in 39.1%, diabetes in 34.8%, prior MRSA infection in 21.7%, immunosuppressed state in 17.4%, and a traumatic injury in 15.2%. The rate of postoperative neurosurgical wound infection in patients who received MRSA-specific prophylactic antibiotic therapy (usually vancomycin) was 7.4% (27 procedures) compared with 32.1% (28 procedures) in patients who received the standard treatment (usually cefazolin) (p = 0.04). Wound care for ICU patients was standardized for postoperative Days 0–7 with chlorhexidine cleaning at bandage changes at 3-day intervals. Wound cultures from neurosurgical site infections in patients with prior MRSA colonization or infection grew MRSA in 7 of 11 patients.

Conclusions

Neurosurgical patients identified with MRSA colonization or a prior history of MRSA infections benefit from specific perioperative care, including prophylactic antibiotics active against MRSA (such as vancomycin) and postoperative wound care with coverings and chlorhexidine antisepsis to reduce MRSA wound colonization.

Dynamic plates in anterior cervical fusion surgery: graft settling and cervical alignment

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To evaluate the effect of graft subsidence associated with the use of dynamic cervical plates on cervical alignment and clinical outcome of patients undergoing anterior cervical decompression and fusion.

SUMMARY AND BACKGROUND DATA

Dynamic cervical plates allow graft loading which may enhance fusion. However, subsidence of the bone graft may result in changes in cervical alignment. The extent of settling of the graft and its impact on cervical alignment has not been determined. Also whether such change in alignment has an impact on clinical outcome is not known.

METHODS

Fifty-five patients with spondylitic myelopathy or radiculopathy underwent anterior cervical decompression and fusion using a dynamic plate for stabilization (ABC, Braun/Aesculap). The surgical indications included myelopathy (n = 21), radiculopathy (n = 30), or myeloradiculopathy (n = 4). Regional and local cervical angles, graft subsidence, and fusion rates were assessed before surgery, immediately after surgery and at 6 months after surgery. Visual analogue scores for neck and radicular pain, Neck Disability Indexes, and Nurick grades for myelopathy were recorded. Patients were observed up for at least 6 months with a median of 14 months (range: 6-48 months).

RESULTS

Radicular pain improved by a median of 5 points (P < 0.0001), whereas Neck pain improved by a median score of 3 (P < 0.0001). A median improvement in Neck Disability Index score of 18 (P < 0.0001) was observed. Nurick grades improved in 68% of patients with myelopathy. Fusion was achieved in 96% of cases. The mean graft subsidence at 6 months was 1.7 mm (range: 0-6 mm). A change of local cervical angle toward lordosis of 5.8 degrees (P < 0.0001) was obtained as a result of surgery. However, there was a loss of 2.7 degrees of lordosis in the first 6 months following surgery (P = 0.001). The extent of subsidence correlated with the local loss of lordosis (P = 0.0003). There was no change in the regional cervical angle in the 6 months following surgery. There was no significant association between clinical outcome and changes in cervical angles.

CONCLUSION

Dynamic anterior cervical plating after anterior decompression and grafting provides comparable fusion rates to that reported following the use of rigid cervical plating. Immediate changes in cervical alignment towards lordosis are partially lost on follow-up. The loss of lordosis is related to the amount of graft settling.

Diagnosing cervical fusion: a comprehensive literature review

Study Design

Comprehensive literature review.

Purpose

To document the criteria for fusion utilized in these studies to determine if a consensus on the definition of a solid fusion exists.

Overview of Literature

Numerous studies have reported on fusion rates following anterior cervical arthrodesis. There is a wide discrepancy in the fusion rates in these studies. While factors such as graft type, Instrumentation, and technique play a factor in fusion rate, another reason for the difference may be a result of differences in the definition of fusion following anterior cervical spine surgery.

Methods

A comprehensive English Medline literature review from 1966 to 2004 using the key words "anterior," "cervical," and "fusion" was performed. We divided these into two groups: newer studies done between 2000 and 2004, and earlier studies done between 1966 and 2000. These articles were then analyzed for the number of patients, follow-up period, graft type, and levels fused. Moreover, all of the articles were examined for their definition of fusion along with their fusion rate.

Results

In the earlier studies from 1966 to 2000, there was no consensus for what constituted a solid fusion. Only fifteen percent of these studies employed the most stringent definition of a solid fusion which was the presence of bridging bone and the absence of motion on flexion and extension radiographs. On the other hand, the later studies (2000 to 2004) used such a definition a majority (63%) of the time, suggesting that a consensus opinion for the definition of fusion is beginning to form.

Conclusions

Our study suggests that over the past several years, a consensus definition of fusion is beginning to form. However, a large percentage of studies are still being published without using stringent fusion criteria. To that end, we recommend that all studies reporting on fusion rates use the most stringent criteria for solid fusion following anterior cervical spine surgery: the absence of motion on flexion/extension views and presence of bridging trabeculae on lateral x-rays. We believe that a universal adoption of such uniform criteria will help to standardize such studies and make it more possible to compare one study with another.

Management of nosocomial external ventricular drain-related ventriculomeningitis

INTRODUCTION

Neurocritical care patients requiring external ventricular drainage are at risk for the development of a device-related infection. Infection rate of external ventriculostomy catheters is high with reported incidences ranging from 5% up to more than 20%. Nosocomial ventriculitis or ventriculomeningitis are potential life-threatening conditions which may contribute to a permanent adverse outcome of the patient. Reducing morbidity and mortality is strongly dependent on prompt diagnosis and on the initiation of appropriate antiinfective therapy.

SCIENTIFIC BACKGROUND

Management of nosocomial ventriculitis is challenging and needs to consider the most likely pathogens involved, local resistance patterns, the nature of the underlying disease, patient factors such as age, comorbidity, and immune status. Further, decisions on catheter exchange and the type and duration of systemic or local antimicrobial therapy have to be made. Because so many factors have to be taken into account, it is evident that the diagnostic and therapeutic approach to nosocomial ventriculitis is difficult to standardize. Staphylococci are the pathogens most frequently identified in nosocomial ventriculitis. Therefore, initial treatment with an antistaphylococcal agent with adequate cerebrospinal fluid penetration may be considered as first-line therapy for this infection.

CONCLUSION

In the review of a contemporary case we will discuss important issues in the management of device-related ventriculitis.

Intestinal carriage of Staphylococcus aureus: how does its frequency compare with that of nasal carriage and what is its clinical impact?

The bacterial species Staphylococcus aureus, including its methicillin-resistant variant (MRSA), finds its primary ecological niche in the human nose, but is also able to colonize the intestines and the perineal region. Intestinal carriage has not been widely investigated despite its potential clinical impact. This review summarizes literature on the topic and sketches the current state of affairs from a microbiological and infectious diseases' perspective. Major findings are that the average reported detection rate of intestinal carriage in healthy individuals and patients is 20% for S. aureus and 9% for MRSA, which is approximately half of that for nasal carriage. Nasal carriage seems to predispose to intestinal carriage, but sole intestinal carriage occurs relatively frequently and is observed in 1 out of 3 intestinal carriers, which provides a rationale to include intestinal screening for surveillance or in outbreak settings. Colonization of the intestinal tract with S. aureus at a young age occurs at a high frequency and may affect the host's immune system. The frequency of intestinal carriage is generally underestimated and may significantly contribute to bacterial dissemination and subsequent risk of infections. Whether intestinal rather than nasal S. aureus carriage is a primary predictor for infections is still ill-defined.

Pharmacologic options for CNS infections caused by resistant Gram-positive organisms

Infectious disease continues to evolve, presenting new and challenging clinical situations for practitioners. Specific to device-related and neurosurgical-related CNS infections, Gram-positive organisms are of growing concern. Current Infection Disease Society of America guidelines for the treatment of CNS infections offer little direction after conventional therapy, consisting of vancomycin, has failed or the patient has demonstrated intolerance. A review of literature evaluating alternative therapies, specifically linezolid, quinupristin/dalfopristin, daptomycin and tigecycline, will be presented. Interpretations of these data are offered followed by a brief presentation of future therapies, including ortavancin, telavancin, dalbavancin, ceftobiprole and iclaprim, all of which possess potent Gram-positive activity.

Successful treatment of methicillin-resistant Staphylococcus aureus meningitis using linezolid without removal of intrathecal infusion pump

✓ Infection of an intrathecal pump system is a rare but serious complication and usually leads to the removal of the pump. The authors report the first case of methicillin-resistant Staphylococcus aureus (MRSA) meningitis in a patient with such a pump successfully treated with linezolid without the need for removal of the intrathecal pump. A 77-year-old woman with cervical myelopathy underwent implantation of an intrathecal pump system for baclofen administration. Two weeks after the procedure she developed meningitis caused by MRSA as isolated in cerebrospinal fluid (CSF) cultures, blood samples, and serum obtained from the pump pouch. Clinically she presented with meningism, somnolence, and signs of sepsis. When a combined intravenous antibiotic treatment regimen of vancomycin and rifampicin resulted in no clinical improvement, that regimen was discontinued and linezolid was administered intravenously as monotherapy. Within 3 days clinical and laboratory findings showed significant improvement. After 1 week of linezolid treatment, blood and CSF cultures were sterile. Intravenous treatment was administered for a total of 3 weeks, after which the patient was treated with oral linezolid for 3 months. During 18 months of follow-up, no new clinical or laboratory signs of infection were observed. These results confirm previous reports of the efficacy of linezolid for the treatment of severe infections of the central nervous system caused by multidrug-resistant Gram-positive bacteria, especially postneurosurgical infections.

Cervical corpectomy with preserved posterior vertebral wall for cervical spondylotic myelopathy: a randomized control clinical study

STUDY DESIGN

Cervical corpectomy with preserved posterior vertebral wall (CPW) had been performed by the senior author (Y.W.) since 1999. A prospective study had been conducted to evaluate the efficacy of CPW since 2001.

OBJECTIVE

To validate the clinical outcome of CPW against conventional corpectomy (CC).

SUMMARY OF BACKGROUND DATA

Anterior surgical managements of cervical spondylotic myelopathy (CSM) include discectomy and corpectomy. Both have significant disadvantages, including low fusion rates and residual symptoms. A procedure incorporating multilevel discectomy, corpectomy with preserved posterior vertebral wall, autograft and plating was described. By keeping the posterior vertebral wall (PW), infringement of the vein plexus and spinal canal was avoided and more fusion site was available.

METHODS

From March 2001 to March 2004, 178 cases of CSM were randomized to undergo CPW (n = 89) or CC (n = 89). Arthrodesis was done with autogenous iliac bone graft or titanium cage supplemented with anterior self-lock plates in both groups. Operation time, blood loss, days of hospitalization, the numbers and types of complications, and preoperative and postoperative JOA scores were recorded. Fusion rate, segmental lordosis, and disc height were assessed by roentgenography. Three-dimensional reconstructions of CT scan were used to confirm fusion evidence.

RESULTS

Average operation time and blood loss decreased significantly in the CPW group (98.06 +/- 19.42 minutes, and 131.69 +/- 62.41 mL) as compared with those in the CC group (108.45 +/- 22.35 minutes, and 181.57 +/- 82.10 mL) (P < 0.05). There were 2 cases of epidural bleeding and 1 case of CSF leak in the CC group. Other complications were minor. JOA improvement scores were similar in both groups. Roentgenograms showed that the fusion rate was 100% at 6 months postoperatively in both groups. CT scans showed that PW fused with grafts and bone dust in cages. Improvement in segmental lordosis and disc height was similar in both groups.

CONCLUSION

CPW is a feasible procedure for anterior decompression and fusion, with safety, complete decompression, and high fusion rate, as long as indicative patients are selected.

Reactivation of dormant lumbar methicillin-resistant Staphylococcus aureus osteomyelitis after 12 years

The adequate treatment of methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis has intrigued clinicians for some time. As the resistance of these pathogens, coupled with the increase in community-acquired cases, continues steadily to rise, clinicians are finding it useful to employ multi-modal approaches for efficacious treatment. The authors present a single case report of a patient with recurrent MRSA osteomyelitis, lumbar paraspinal and epidural abscess. He was found to have decreased muscle strength and was hyporeflexic in the involved extremity. Serum testing demonstrated MRSA bacteremia. Neuroimaging studies revealed evidence of paraspinal abscess and a presumed herniated nucleus pulposus at the L5/S1 interspace with significant nerve root compromise. Despite antimicrobials, his symptoms persisted, necessitating surgical exploration. At surgery, paraspinal and epidural abscesses were encountered and debrided; however, no herniated disc was visualized. This case demonstrates the diagnostic and therapeutic dilemmas with which these lesions present. We postulate that the MRSA osteomyelitis/discitis pathogens were walled off in the disc space and subsequently inoculated the soft tissues with ensuing bacteremia. We concur that antimicrobial treatment should be the first line of therapy for these patients; however, surgical debridements and cautious spinal instrumentation should be employed where appropriate.

Comparison of multisegment anterior cervical fixation using bone strut graft versus a titanium rod and buttress prosthesis: analysis of outcome with long-term follow-up and interview by independent physician

STUDY DESIGN

A retrospective study of 73 consecutive patients who underwent cervical corpectomy and anterior strut fixation over 3 or more disc levels between July 1989 and May 1999.

OBJECTIVE

To compare the efficacy of cervical spine fixation by autologous strut graft from iliac crest or fibula versus a titanium prosthesis without bone graft.

SUMMARY OF BACKGROUND DATA

Strut grafting after multilevel anterior cervical corpectomy remains a challenging procedure, with published dislocation rates from 0% to 71%, and nonunion from 0% to 54%. This paper describes a quicker and easier alternative to the use of a bone strut, imparting a very high degree of immediate spinal stability, and osseous integration equivalent to bone fusion.

METHODS

Thirty-eight bone-graft operations and 38 titanium prosthesis operations were performed on 73 patients between July 24, 1989 and May 20, 1999. Average follow-up was 53.2 months (range 19.8-134).

RESULTS

The group of patients who received the prosthesis was significantly older than the bone-grafted group and required significantly more segments excised, but operation times were significantly shorter than for the bone strut operation. The titanium prosthesis had a lower incidence of dislodgement in the early postoperative period (1/38 vs. 4/38 for bone struts) but a higher rate of late reoperation (4/38 vs. 1/38 for bone struts). The SF-36 scores in the domain of Physical Function (only) were significantly higher in the bone-grafted group (P = 0.016, Mann Whitney), consistent with the difference in mean ages of the 2 groups. The groups were indistinguishable by Odom criteria, patient verdict, pain scores, analgesic intake, length of hospital stay, radiologic fusion rate, and residual symptoms.

CONCLUSION

A titanium rod and buttress prosthesis may be a faster and easier alternative to conventional iliac crest/fibula autograft after multisegmental cervical vertebral corpectomy.

Pharmacokinetics of intravenous linezolid in cerebrospinal fluid and plasma in neurointensive care patients with staphylococcal ventriculitis associated with external ventricular drains

The pharmacokinetic profile of linezolid in cerebrospinal fluid (CSF) in five neurointensive care patients with staphylococcal ventriculitis was studied. The mean area under concentration-time curve (+/- standard deviation) was 63 +/- 18.9 mg x h/liter, with a CSF-to-plasma ratio of 0.8 +/- 0.3. Times above MIC in CSF were 99.8% and 57.2% for pathogens with MICs of 2 mg/liter and 4 mg/liter, respectively.

Topical Application of Bacitracin Ointment Is Associated with Decreased Risk of Mediastinitis after Median Sternotomy

BACKGROUND

The diagnosis of mediastinitis after open-heart surgery is infrequent but dreaded as it carries a high morbidity and mortality. The purpose of this study was to investigate the impact that topical antibacterials would have on the postoperative mediastinitis rate.

METHODS

Data were collected from 2455 consecutive patients who underwent sternotomy and cardiopulmonary bypass for both valvar and ischemic heart disease. Prior to 1999, patients (n = 1036) underwent surgery with standard perioperative intravenous antibiotics but no application of bacitracin. After 1999, patients (n = 1419) underwent surgery with intravenous antibiotics and application of bacitracin ointment to the sternotomy incision after closure.

RESULTS

Cases of mediastinitis occurred in 12 patients (1.2%) not treated with bacitracin, which required re-exploration, sternectomy, and soft tissue closure of the mediastinum. Alternatively, 3 patients (0.2%) in the group treated with bacitracin developed mediastinitis (P < .01). Therefore, the use of topical antibacterials was associated with a 6-fold reduction in the risk of mediastinitis after cardiac surgery. This significant difference in the infection rate was observed even though the percentage of patients with risk factors for mediastinitis was equal to greater than the group not treated with bacitracin. Non-bacitracin versus bacitracin: diabetics, 298 versus 484; emergency operations, 24 versus 50; bilateral internal thoracic grafts, 28 versus 29; and obesity (body mass index >30), 294 versus 396.

CONCLUSIONS

The use of topical antibacterials is associated with a decrease in the risk of mediastinitis after cardiac surgery.

Outcome predictors and complications in the management of intradural spinal tumours

The results of the management of 115 patients with intradural spinal tumours are presented. Data was collected retrospectively from the case notes. Tumours were categorized as intramedullary or extramedullary for statistical analysis. Meningioma, schwannoma and ependymoma accounted for 70% of tumours. Complete macroscopic excision was achieved in 84% of extramedullary and 54% of intramedullary tumours. There were two post-operative deaths, one of which was secondary to methacillin-resistant staphylococcus aureus (MRSA) meningitis. Cerebrospinal fluid leak (10%) and meningitis (7%) were the commonest complications. Ninety-six percent of patients with extramedullary tumours improved or remained unchanged on the Frankel scale. In the intramedullary group, 82% remained unchanged or improved after treatment. Pre-operative functional status was a predictor of good post-operative function for intra- and extramedullary tumours and for intramedullary tumours a good post-operative Frankel score predicted long-term survival.

Clinical experience with linezolid for the treatment of central nervous system infections

Linezolid, an oxazolidinone, exhibits bacteriostatic activity against virtually all Gram-positive bacteria and even covers atypical organisms like mycobacteria and Nocardia. However, little is known about its effectiveness for central nervous system (CNS) infections. We report on our good experience with linezolid for the treatment of CNS infections in 10 patients, amongst whom three were caused by mycobacteria. While six of our patients clinically improved during linezolid therapy even after failure of various antibiotics, it was unsuccessful in one case. Side-effects were only mild gastrointestinal problems in one patient after long term-treatment, which however led to the cessation of therapy. Linezolid appears to be a safe alternative to vancomycin for therapy-resistant CNS infections because of its good CSF penetration and few side-effects.

Comparison of Animal Models with Soft Tissue Infection by Different Bacilli

In clinical medicine improved diagnostic methods for the detection of infection are needed. A good infectious animal model is very important for the development of a new diagnostic method or drug. The purpose of this study was to establish a good animal model with soft tissue infection. Twenty-four SD rats were divided into four groups (6 in each group). Various bacilli including Staphylococcus aureus (S. aureus), Streptococcus pneumoniae (S. pneumoniae), and Escherichia coli (E. coli) were injected intramuscularly into the left caudal thighs of three groups of rats to create soft tissue infection. In addition, normal saline was injected into the left caudal thighs of ten rats which were used as controls. Before and 48 hr after inoculation of the bacilli, a blood sample (0.5 ml) was taken from each rat and analyzed to determine the white blood cell count and differentiated cell count. In addition, 48 hr after the inoculation, 0.2 mCi of gallium-67 was injected via the tail vein. Gallium scan was performed at 24 hr and 48 hr after administration of the radiotracer. The dorsal view of both hind legs was imaged and analyzed by computers to calculate the lesion-to-normal (L/N) ratio. After imaging, all rats were sacrificed and specimens from portions of the infected thigh muscle were sent for histopathologic investigation to confirm the infection. The increase in both the WBC counts and the segmented polymorphonuclear leukocytes (PMNs) were most significant in the S. aureus group, followed by the S. pneumoniae group, E. coli group and normal control groups. The rats with S. aureus infection had significant gallium uptake at the site of infection and the highest L/N ratio of 2.14 on the 24-hr image and 2.0 on the 48-hr image. The rats with S. pneumoniae had the second highest L/N ratio (1.41 at 24 hr, and 1.48 at 48 hr). The L/N ratio for the E. coli group was 1.27 at 24 hr and 1.35 at 48 hr. No obviously abnormal gallium uptake was demonstrated in the normal controls. We conclude that all three bacilli induced a soft tissue infection in SD rats. S. aureus resulted in the most significant infectious signs.