Risk factors for unfavorable clinical outcomes in patients with brain abscess in South Korea.

BACKGROUND: Brain abscess can be life-threatening and manifest various neurological findings, although the mortality rate has decreased recently. We investigated the risk factors for unfavorable outcomes of patients with brain abscess. METHODS: A retrospective cohort study examined patients with brain abscess seen from May 2005 to December 2018 in a tertiary care hospital in Seoul, South Korea. We reviewed the medical records for clinical findings, therapeutic modalities, and prognostic factors of brain abscess. Unfavorable clinical outcomes were defined as death, moderate to severe disability with neurological deficits, or vegetative state at 1 year or at the time of discharge from outpatient follow-up. RESULTS: The study enrolled 135 patients: 65.2% were males; the mean age was 56 years. 35.6% had unfavorable outcomes. In multivariate analysis, higher Sequential Organ Failure Assessment (SOFA) (p < 0.001), pre-existing hemiplegia (p = 0.049), and higher Charlson comorbidity index (CCI) (p = 0.028) were independently associated with unfavorable outcomes. CONCLUSIONS: Higher SOFA, pre-existing hemiplegia and higher Charlson comorbidity index were significant risk factors for unfavorable clinical outcomes in patients with brain abscess.

Brain Abscess Caused by Nocardia: Case Report and Literature Review

Nocardia brain abscess is a rare clinical entity, accounting for 2% of all brain abscesses, associated with high morbidity and amortality rate 3 times higher than brain abscesses caused by other bacteria. Proper investigation and treatment, characterized by a longterm antibiotic therapy, play an important role on the outcome of the patient. The authors describe a case of a patient without neurological comorbidities who developed clinical signs of right occipital lobe impairment and seizures, whose investigation demonstrated brain abscess caused by Nocardia spp. The patient was treated surgically followed by antibiotic therapy with a great outcome after 1 year of follow-up.

Clinical outcomes of different treatments and risk factors in patients with otogenic brain abscess, a real-world evidence-based retrospective study.

BACKGROUND: Otogenic Brain Abscess (OBA) is a life-threatening complication secondary to otitis media, but its appropriate management remains controversial. OBJECTIVES: To understand the demographic characteristics, management, and variables that affect the outcomes of patients with OBA based on our experiences over 11 years. MATERIAL AND METHODS: Clinical data were collected for 41 patients. Prognostic factors associated with mortality were assessed, and clinical outcomes compared among groups receiving different treatments. RESULTS: Among the 41 patients, 19.6% did not undergo surgery, 39.0% were treated with two-stage surgery (otological surgery and neurosurgery) and 41.4% were treated with single-stage surgery (otological surgery or neurosurgery). Overall mortality rate was 32.5%, and mortality was significantly higher in patients with invasion of the petrous apex (odds ratio [OR]: 7.81, 95% confidence interval [95% CI]: 1.26-48.36), and lower in those with appropriate surgical management (single otological surgery, OR: 0.07, 95% CI: 0-0.97; single neurosurgery, OR: 0.13, 95% CI: 0.02-1.0; two-stage surgery, OR: 0.08, 95% CI: 0.01-0.64) or a higher Glasgow Coma Scale (GCS) score at admission (OR: 0.64, 95% CI: 0.44-0.93). CONCLUSIONS AND SIGNIFICANCE: Data on invasiveness and pre-surgery GCS greatly aid in predicting the prognosis of OBA patients. Early evaluation will facilitate decision-making by physicians treating OBA patients.

Long-term Mortality and Risk of Epilepsy in Children and Young Adults With Brain Abscess.

BACKGROUND: The long-term prognosis of brain abscess is unclear. METHODS: Using nationwide, population-based medical registries, we included all individuals <20 years of age hospitalized with first-time diagnosis of brain abscess in Denmark from 1982 to 2016. A comparison cohort individually matched for age, sex and residence was identified, as were siblings of all study participants. Next, cumulative incidence curves of mortality and new-onset epilepsy were constructed, and Cox regression was used for analyses of hazard rate ratios (HRRs) with 95% confidence intervals. RESULTS: We identified 155 brain abscess patients and 1,550 population controls with median follow-up times of 15 years (interquartile range, 6-25) and 16 years (interquartile range, 11-26). Ear-nose-throat infections (22%) and congenital heart disease (13%) were the most common predisposing conditions for brain abscess. Overall mortality was 21/155 (14%) in brain abscess patients versus 20/1,550 (1%) in population controls. The corresponding HRRs were 150 (95% confidence interval: 19.8-1,116) after 1 year of observation, 24.6 (4.78-127) after 2-5 years and 0.66 (0.09-4.98) after 6-30 years. New-onset epilepsy occurred in 28% of 30-day brain abscess survivors versus 1% in population controls yielding a HRR of 29.6 (14.4-60.8) adjusted for previous head trauma, stroke and cancer. Analyses of sibling cohorts showed that family-related factors did not explain the observed increased risks of death or epilepsy among brain abscess patients. CONCLUSIONS: Brain abscess is associated with increased risk of mortality for up to 5 years. New-onset epilepsy occurred in 28% of survivors and remained a risk for several years after infection.

Incidence and mortality of brain abscess in Denmark: a nationwide population-based study.

OBJECTIVES: To examine the incidence and mortality of brain abscesses. METHODS: We accessed nationwide population-based medical registries to obtain data for patients with first-time brain abscesses in Denmark from 1982 through 2016. Annual age- and sex-standardized incidence rates with 95% confidence intervals were calculated and compared by direct standardization. We used Cox regression to compute mortality rate ratios adjusted for age and year groups, sex and Charlson comorbidity index score. RESULTS: We identified 1384 patients (37% female). The overall standardized incidence rate of brain abscess was 0.76 per 100 000 person-years (95% confidence interval 0.70-0.81). The incidence rates gradually increased from 0.60 during 1982-88 to 0.90 per 100 000 person-years during 2010-16, yielding an incidence rate ratio of 1.50 (95% confidence interval 1.26-1.79). This increase in incidence was most pronounced in the proportions of brain abscess patients >40 years of age and those with immuno-compromise. The 1-year mortality declined from 29% during 1982-88 to 20% during 2010-16, yielding an adjusted mortality rate ratio of 0.44 (95% confidence interval 0.31-0.63). Risk factors for death were advanced age, Charlson comorbidity index >0, immuno-compromised status and congenital heart disease. CONCLUSIONS: The incidence of brain abscess in Denmark is low but increasing, especially in the elderly, along with an increasing proportion of brain abscess patients with immuno-compromise. The prognosis has improved during the last decades, but mortality remains high. Risk factors for death in our study were advanced age, presence of comorbidity, immuno-compromised status and congenital heart disease.

Risk Factors Associated With Mortality in Patients With Otogenic Brain Abscess.

OBJECTIVE: Otogenic brain abscess is a well-recognized clinical condition that describes brain abscess secondary to an ear infection or mastoiditis. Current evidence remains limited on risk factors associated with mortality as most data are from case series. We aimed to 1) report the mortality rate among patients who did and did not receive mastoidectomy 2) identify factors associated with inpatient mortality. STUDY DESIGN: Retrospective cohort study. SETTING: Multi-institutional. PATIENTS: We identified a cohort of patients for years 2008 to 2014 who in their inpatient hospitalization carried the diagnoses of both brain abscess and infectious ear disease. INTERVENTIONS: Inpatient neurotology and neurosurgical procedures. MAIN OUTCOME MEASURES: A multivariable logistics regression model was built to identify the factors associated with inpatient mortality. RESULTS: The final analysis included 252 patients, of which 84 (33.3%) underwent mastoidectomy. The rate of inpatient morbidity and mortality were 17.5% and 4.0%, respectively. The rate of mortality in patients without mastoidectomy versus those with mastoidectomy was 4.2% versus 3.6%, respectively (p > 0.99). The odds of inpatient mortality were significantly increased for every 10-year increase in age (odds ratio [OR] 2.73, 95% confidence interval [CI]: 1.39-7.01, p = 0.011) and for Black compared to White patients (OR: 45.81, 95% CI: 4.56-890.92, p = 0.003). CONCLUSION: Older age and Black race were associated with increased odds of inpatient mortality and there were no significant differences in mortality between mastoidectomy cohorts. This research serves to generate further hypotheses for larger observational studies to investigate the association between sociodemographic factors and surgical variables with outcomes among this surgical population.

Clinical Characteristics and Course of Postoperative Brain Abscess.

BACKGROUND: Cerebral abscesses after brain surgery are rare but severe and life-threatening complications. We sought to analyze the clinical aspects of those patients and thereby reveal risk factors and the relevant aspects for their future therapy. METHODS: We identified 44 patients (23 male, 21 female) undergoing surgery or frameless stereotactic drainage at our center from March 2009 to January 2018. We conducted 12,101 cranial surgeries during that time. RESULTS: The mean age was 55 years (range 21-82 years). The median duration between brain surgery and the after brain abscess was 1.5 months (range 1-23 months). Previous brain surgeries were emergency procedures in 27% of the cases. The frequency of surgery type was as follows: tumor resection (61%), craniotomy for traumatic brain injury (16%), aneurysm surgery (7%), biopsies (5%), hemicraniectomy after malignant cerebral infarction (5%), and other. We performed 1.3 surgeries per patient followed by antibiotic treatment for 4 weeks (=median) according to the respective germ spectrum. The germ entity was successfully identified in 39 patients (89%). In 18 cases (41%), we identified Staphylococcus aureus. In total, 20.5% of the patients died during the follow-up period. The mortality rate for patients with isolated bacteria was 18% compared with 40% for patients without isolation of specific microorganisms. CONCLUSIONS: Secondary brain abscess is a rare complication and occurs mainly in patients with tumors and patients receiving emergency surgery. In total, 41% of the patients suffered from a S. aureus infection. Isolation of the responsible microorganisms is often possible and leads to improved outcomes.

Predictors of clinical outcomes among patients with brain abscess in Thailand.

Although brain abscess is a fatal neurological infection, the studies in Thailand are quite limited and outdate. This study aims to identify predictors of mortality among patients with brain abscess in Thailand. Patients with a diagnosis of brain abscess admitted to Songklanagarind Hospital, a referral tertiary care hospital in southern Thailand, between 2002 and 2017 were enrolled into this retrospective case control study. Demographic data, neurological status, clinical presentations, predisposing factors, microbiological profiles, neuroimaging findings, treatments, and outcomes were collected from electronic medical records. Predictors of death outcome were analyzed by univariate and multivariate logistic regression analysis. Among eighty-one patients enrolled into the study, forty-seven patients (58.0%) were male and 34 patients (42.0%) were female. The overall mean age (±SD) was 47.68 (±16.92) years old. The major predisposing factors of brain abscess were an immunocompromised state (42.0%) and the extension of a paracranial infections (24.7%). The common clinical presentations included headache (61.7%), fever (50.6%), and hemiplegia (34.6%). Eleven patients (13.6%) were dead at hospital discharge. The independent factor associated with death outcome identified by multivariate analysis was confusion (odds ratio 7.67, 95% CI 1.95-30.14; p = 0.003). In summary, the current study shows that an immunocompromised state is a significant predisposing factor of brain abscess. The independent factor associated with death outcome was confusion which was correlated with septic encephalopathy.

Dexamethasone Administration and Mortality in Patients with Brain Abscess: A Systematic Review and Meta-Analysis.

BACKGROUND: Dexamethasone has been used to treat cerebral edema associated with brain abscess. Whereas some argue that dexamethasone might aid antibiotic treatment, others believe that because of its immunosuppressive characteristics, it might have a negative impact on outcomes. How corticosteroid use affects overall mortality of brain abscess patients remains unclear. METHODS: A systematic search of the literature was conducted in accordance with PRISMA guidelines. PubMed, Embase, and Cochrane databases were utilized to identify all studies related to patients diagnosed with a brain abscess treated with dexamethasone. The main outcome of interest was mortality. Pooled effect estimates were calculated using fixed-effects (FE) and random-effects (RE) models. RESULTS: After removal of duplicates, 1681 articles were extracted from the literature of which 11 were included. These included 7 cohort studies and 4 case series. Indications to administer dexamethasone were either hospital brain abscess protocol or clinical presentation of cerebral edema. The 7 cohort studies involving 571 patients with brain abscesses comprised of 330 patients treated with standard of care (SOC) plus dexamethasone and 241 patients treated with SOC alone, after aspiration or surgical management of the abscess in either group. Pooling results from all seven cohort studies demonstrated a nonsignificant mortality benefit comparing SOC and dexamethasone patients to SOC patients (FE: risk ratio [RR], 0.94; 95% confidence interval [CI], 0.64-1.37; RE: RR, 0.95; 95% CI, 049-1.82; I2 = 53.9%; P for heterogeneity = 0.04). CONCLUSIONS: In patients with a brain abscess treated with antibiotics, the use of dexamethasone was not associated with increased mortality.

Pyogenic brain abscess in children: a Tunisian multi-center experience.

BACKGROUND: Brain abscess (BA) is an uncommon intracranial suppurative infectious disease, especially in children. Treatment involves surgery and prolonged courses of antibiotics. OBJECTIVES: Our study aimed to describe clinical characteristics of children with BA treated in middle Tunisian health centers. METHODS: A retrospective study lasting 19 years (1995-2014) was conducted in Tunisia middle region. Forty one children having radiologic abnormalities suggestive of BA and confirmed per operative lesions were included. Mycobacterial, parasitic or fungal abscesses were excluded. Medical records were analyzed for age, gender, presenting symptoms, predisposing factors, imaging, microbiology results, treatment and outcome. RESULTS: The mean age was 4.9 years. The most common clinical presentations were intracranial hypertension symptoms (87%). BA was diagnosed in 95.1% on the basis of cranial imaging. The majority of abscesses was supra-tentorial (92.6%). The most frequent etiology was loco-regional infections (63.4%). No predisposing factor was found in 17%. Intravenous antibiotics were given in all cases with surgical drainage in 63.4%,. Causative organisms were identified in 53.7%. The mortality rate was 24.3%. Age less than 2 years was the only statistically significant prognostic factor identified. CONCLUSION: Our study confirmed the severity of this pathology and underlined the importance of early diagnosis and management.

CONSORT: May stereotactic intracavity administration of antibiotics shorten the course of systemic antibiotic therapy for brain abscesses?

BACKGROUND: Despite advances in surgical techniques in the management of the brain abscess, continuous systemic long-term antibiotics are necessary and crucial. This study was designed to evaluate the effect of intracavity administration of high-dose antibiotics on the course of antibiotic therapy. METHODS: Between 2003 and 2013, 55 patients with bacterial brain abscesses (83 abscesses) were treated with stereotactic aspiration and intracavity injection of high-dose antibiotics combined with a short course systemic antibiotic therapy. Antibiotics of one-eighth daily systemic dosage were injected into the abscess cavity after stereotactic aspiration and intravenous antibiotics were given in all patients for 3 to 4 weeks. The results of the group treated with stereotactic aspiration and intracavity injection of antibiotic solution were compared to the results of our previous patients treated by stereotactic aspiration only. RESULTS: Thirty-nine males and 16 females (age ranging from 1.5 to 76 years; mean age 38.7 years) were included in this study. During the follow-up (mean 26.2 months, ranging from 6 to 72 months), all the abscesses subsided with no recurrence. No adverse effects related to topical use of antibiotics occurred. At the end of follow-up, 38 patients had good outcomes, 11 had mild neurological deficits, 3 had moderate deficits, 1 was in vegetative state, and 2 died of accidents not related to brain abscesses. Compared with conventional stereotactic aspiration and drainage, intracavity injection of antibiotics shorted the course of consecutive systemic intravenous antibiotics by average 10.8 days without an increase of the recurrence rate of abscesses. CONCLUSIONS: Our results indicate that topical application of antibiotics into the brain abscess cavity helps to reduce the length of systemic antibiotic therapy, decreases the abscess recurrence rate, avoids the side effects of long-term high dose antibiotics, shortens the hospitalization and reduces treatment costs.

Evidence of Archaeal Methanogens in Brain Abscess.

Background: Methanogens are antibiotic-resistant anaerobic archaea that escape routine detection in clinical microbiology. We hypothesized that methanogens are part of the anaerobic community that cause brain abscess. Methods: Methanogens were investigated in 1 index sample using specific polymerase chain reaction (PCR) sequencing and culture. The pathogenesis of a methanogen isolate was assessed in a mouse model. Archaea-specific quantitative (q) PCR and metagenomics were used to detect specific archaeal sequences in brain abscess samples and controls. Results: In 1 index sample, routine culture found Porphyromonas endodontalis and Streptococcus intermedius, and specific culture found Methanobrevibacter oralis susceptible to metronidazole and fusidic acid. Archaea-targeted PCR sequencing and metagenomics confirmed M. oralis along with 14 bacteria, including S. intermedius. Archaea-specific qPCR yielded archaea in 8/18 brain abscess specimens and 1/27 controls (P < .003), and metagenomics yielded archaea, mostly methanogens, in 28/32 brain abscess samples, and no archaea in 71 negative controls (P < 10-6). Infection of mice brains yielded no mortality in 14 controls and death in 17/22 M. oralis-inoculated mice (P < 10-6), 32/95 S. intermedius-inoculated mice (P < 10-6), and 75/104 mice inoculated with M. oralis mixed with S. intermedius (P < 10-6) 7 days post-inoculation. Conclusion: Methanogens belong to the anaerobic community responsible for brain abscess, and M. oralis may participate in the pathogenicity of this deadly infection. In mice, a synergy of M. oralis and S. intermedius was observed. Antibiotic treatment of brain abscess should contain anti-archaeal compounds such as imidazole derivatives in most cases.

Otogenic Intracranial Abscesses, Our Experience Over the Last Four Decades.

OBJECTIVE: To evaluate the predisposing factors for otogenic intracranial abscesses, assess their changes over time, and analyze how they differ from those due to other causes. MATERIALS AND METHODS: The medical records of all patients treated for otogenic intracranial abscesses, between 1970 and 2012 at a tertiary referral center, were retrospectively analyzed. The analysis included patient demographics, clinical characteristics, causative pathogens, treatments, outcomes, and comparisons of otogenic and non-otogenic intracranial abscesses. RESULTS: Of all intracranial abscesses, 11% (n=18) were otogenic. In the 1970s, otogenic infections were a common predisposing factor for intracranial abscess; but within our study period, the incidence of otogenic intracranial abscesses decreased. Most (94%) otogenic cases were due to chronic suppurative otitis media and 78% were associated with cholesteatoma. Most patients (94%) had ear symptoms. The most common presenting symptoms were discharge from the infected ear (50%), headache (39%), neurological symptoms (28%), and fever (17%). The most common pathogens belonged to Streptococcus spp. (33%), Gram-negative enteric bacteria (22%), and Bacteroides spp. (11%). Neurosurgery was performed on all patients, 69% of which were prior to a later ear surgery. Surgery of the affected ear was performed on 14 patients (78%). A favorable recovery was typical (78%); however, one patient died. CONCLUSION: Otogenic intracranial abscesses were most commonly due to a chronic ear infection with cholesteatoma. Ear symptoms and Gram-negative enteric bacteria were more common among patients with otogenic than non-otogenic intracranial abscesses.

[The specific clinical features of otogenic intracranial complications: the current views].

The objective of the present study was to elucidate the specific clinical features of otogenic intracranial complications (ICC) encountered in the current otorhinolaryngological practice. The work is based on the results of the retrospective analysis of 106 adult patients presenting with otogenic intracranial complications admitted for the treatment to multidisciplinary clinics of Sankt-Peterburg and Krasnoyarsk. Forty six (42.5%) patients presented with acute otitis media. 90% of them had suppurative destructive mastoiditis. In sixty (56.6%) patients, chronic suppurative otitis media (epitympanophonia) was associated with the extensive destructive process spreading toward dura mater of the medial and posterior cranial fossae and onto the sigmoid sinus. The prevalence of intracranial complications among the adult patients suffering from suppurative otitis media and treated in the otorhinolaryngological clinics amounted to 3.17%. The overall structure of otogenic intracranial complications was as follows: meningitis 42.5%, brain and cerebellum abscess 24.5%, suppurative meningoencephalitis 19.8%, sinus thrombosis 5.7%, epidural and subdural empyemas 4.7%, the combined suppurative brain lesions 2.8%. Systemic inflammatory response syndrome (sepsis) was diagnosed in 33 (31%) patients with otogenic ICC. The high intrahospital mortality rate among the patients with this condition (20.8%) is emphasized. The main causes of the fatal outcome in the patients with otogenic intracranial complications are supposed to be brain oedema with the concomitant development of dyslocation syndrome and sepsis.

Brain abscesses in children: results of 24 children from a reference center in Central Anatolia, Turkey.

Childhood brain abscesses are a rare and potentially life-threatening condition requiring urgent diagnosis and treatment. This retrospective study analyzed the clinical and radiologic findings of 24 (7 girl, 17 boys) cases with brain abscess. Mean age was 92.98 ± 68.04 months. The most common presenting symptoms were nausea-vomiting (45.8%) and headache (41.7%). Brain abscess was most commonly located in the frontal region. Diffusion restriction was determined in 78.4% of lesions. The mean apparent diffusion coefficient value in these lesions was 0.511 ± 0.23 × 10(-3) mm(2)/s. Cultures were sterile in 40% of cases. Antimicrobial therapy was given to only 16.7% of cases. Predisposing factors were identified in 91.6% of cases (congenital heart disease in 20.8% and immunosuppression in 20.8%). Mortality level was 12.5%. In conclusion, immunocompromised states, and congenital heart disease have become an important predisposing factor for brain abscesses. Effective and prompt management should ensure better outcome in childhood.

The accessory gene regulator (agr) controls Staphylococcus aureus virulence in a murine intracranial abscesses model

Background: Intracranial abscesses are associated with high mortality. Staphylococcus aureus is one of the main pathogens that cause intracranial infection. Until now, there is no report to identify the key effectors of S. aureus during the intracranial infection. Methods: The murine intracranial abscesses model induced by S. aureus was constructed. The vital sign and survival rate of mice were observed to evaluate the infection. Histological examination was used to diagnose the pathological alterations of mouse tissues. The sensitivity of S. aureus to whole blood was evaluated by whole-blood killing assay. Results: In murine intracranial abscesses model, it was shown that the mortality caused by the accessory gene regulator (agr) locus deficient strain was significant decreased compared with its parent strain. Moreover, we found that RNAIII, the effector of agr system, was essential for the intracranial infection caused by S. aureus. In the further investigation, it was shown that restoration the expression of α-toxin in agr deficient strain could partially recover the mortality in the murine intracranial abscesses model. Conclusion: Our data suggested that the agr system of S. aureus is an important virulence determinant in the induction and mortality of intracranial abscesses in mice. .

A retrospective study on the aetiology, management, and outcome of brain abscess in an 11-year, single-centre study from China.

BACKGROUND: Brain abscesses continue to pose diagnostic and therapeutic challenges in developed and developing countries. Their aetiology and management remain complex and unclear, making improvement of treatments and outcome difficult. METHODS: To determine the demographics, management, and the variables that affect the outcome in subjects with brain abscesses treated at a single centre over an 11-year period, we retrospectively analysed data in 60 patients with brain abscesses surgically treated with stereotactically guided aspiration or open craniotomy excision in Shanghai Changzheng Hospital between January 2001 and December 2011. Such variables as age, gender, Glasgow Coma Scale (GCS) score at admission, clinical presentation, location, number of lesions, predisposing factors, mechanism of infection, aetiological agent, and therapy were analysed independently. RESULTS: Our analysis demonstrated that patient age and gender were factors that influence the occurrence of brain abscess; female patients and patients greater than 40 years of age were most likely to suffer a brain abscess. We also found that a patient's GCS score upon admission did not influence outcome. While frequency of successful culturing of the infectious agent was low, positive cultures were obtained in only 8 of the cases (13.33%), in which the most common isolate was Streptococcus milleri. Outcome was favourable in 78.33% of the subjects, while the mortality rate was 20%. The outcome of one patient was poor due to the abscess in the basal ganglia region. CONCLUSIONS: Stereotactically guided aspiration is an effective treatment for brain abscess with an overall favourable outcome. Mortality due to brain abscess was not directly related to surgery nor surgical technique. Additional studies will continue to reveal patients trends that may improve treatment for brain abscess.

The accessory gene regulator (agr) controls Staphylococcus aureus virulence in a murine intracranial abscesses model.

BACKGROUND: Intracranial abscesses are associated with high mortality. Staphylococcus aureus is one of the main pathogens that cause intracranial infection. Until now, there is no report to identify the key effectors of S. aureus during the intracranial infection. METHODS: The murine intracranial abscesses model induced by S. aureus was constructed. The vital sign and survival rate of mice were observed to evaluate the infection. Histological examination was used to diagnose the pathological alterations of mouse tissues. The sensitivity of S. aureus to whole blood was evaluated by whole-blood killing assay. RESULTS: In murine intracranial abscesses model, it was shown that the mortality caused by the accessory gene regulator (agr) locus deficient strain was significant decreased compared with its parent strain. Moreover, we found that RNAIII, the effector of agr system, was essential for the intracranial infection caused by S. aureus. In the further investigation, it was shown that restoration the expression of α-toxin in agr deficient strain could partially recover the mortality in the murine intracranial abscesses model. CONCLUSION: Our data suggested that the agr system of S. aureus is an important virulence determinant in the induction and mortality of intracranial abscesses in mice.

Brain abscesses: clinical experience and outcome of 52 consecutive cases.

BACKGROUND: Brain abscesses are still a very important pathology, with high mortality and morbidity, even with the advancement of imaging technologies and antibiotic treatment. In this study, we analyzed the relationship between clinical, biological and therapeutic features at admission and clinical outcome in patients with brain abscesses. MATERIAL AND METHOD: This is a retrospective study over 52 consecutive patients with brain abscesses treated in our Neurosurgical Department during 8 years, between January 2003 and December 2011. Laboratory tests, cerebral CT or MRI scans, blood and urine cultures were performed. Surgical treatment consisted of either CT guided stereotactic aspiration or craniotomy with the resection of the abscess. Materials from the brain abscess were cultured for aerobic and anaerobic bacteria. Parenteral antibiotic therapy usually lasted between 6 to 8 weeks. RESULTS: Clinical outcome was assessed at 6 months endpoint by using Glasgow Outcome Scale (GOS). The most common cause of brain abscess was hematogenous spread. There were 41 patients with solitary and 11 with multiple brain abscesses. Regarding microbiological findings, we obtained positive cultures from brain materials in 41 patients. Stereotactic aspiration was performed in 33 patients, surgical excision in 15 and medical therapy alone in 4 patients. As clinical outcome, 84.6% patients had a favorable outcome (GOS 5 and 4) and 15.4% had an unfavorable outcome (severe disability - 4 and death - 4). CONCLUSIONS: Early diagnosis, optimal surgical intervention and timely use of appropriate antibiotics are essential for a good outcome. No significant difference in outcome was found among various surgical treatment modalities. For mortality, initial Glasgow Coma Score (GCS) 8, associated predisposing factors and systemic infections were significant contributing factors.