Streptococcus pneumoniae deficient in pneumolysin or autolysin has reduced virulence in meningitis

BACKGROUND: The role played by pneumolysin and autolysin in pneumococcal meningitis is poorly understood. METHODS: A rat model was used to investigate the disease, in which surgical implantation of a cisternal catheter allowed bacterial instillation and cerebrospinal fluid (CSF) sampling. RESULTS: CSF infection of rats with wild-type pneumococci caused meningitis within 26 h, whereas isogenic mutants that do not express pneumolysin (DeltaPly) or autolysin (LytA(-)) caused very mild or no disease. Wild-type infections resulted in pneumococci in the CSF and cortical homogenates, but a minority of the rats infected with DeltaPly or LytA(-) had bacteria in these locations at 26 h. Leukocyte numbers in the CSF were similar after infection with all pneumococci; however, neutrophils and monocytes predominated after wild-type infection, whereas lymphocytes and atypical lymphocytes predominated after infection with the mutants. Wild-type pneumococci caused disruption to the ependyma, but this was not observed in rats infected with DeltaPly or LytA(-). Cells surrounding the ventricles in wild type-infected animals expressed caspase 3, and astrocytes had hypertrophy; both findings were absent in rats infected with the mutants. CONCLUSIONS: This study provides strong in vivo evidence that pneumolysin and autolysin play crucial roles in the pathogenesis of pneumococcal meningitis.     

Soluble urokinase receptor is elevated in cerebrospinal fluid from patients with purulent meningitis and is associated with fatal outcome

The urokinase-type plasminogen activator system has been suggested to play a pathophysiological role in brain damage. The aim of this study was to evaluate CSF levels of suPAR in 183 patients clinically suspected of having meningitis on admission. Of these, 54 patients were found to have purulent meningitis, 63 had lymphocytic meningitis, 12 had encephalitis, and 54 patients were suspected of, but had no evidence of, meningitis. There was a significant difference in suPAR levels among patient groups (Kruskal Wallis test, p < 0.0001) with significantly higher CSF suPAR levels in patients with CNS infection (purulent meningitis: median suPAR 2.41 microg/l (range 0.12-35), lymphocytic meningitis: 1.10 microg/l (0.15-5.31), and encephalitis (1.77 microg/l (0.17-11.7)) than in patients without meningitis (0.64 microg/l (0-5.34) (Dunn's multiple comparison test, p < 0.05). Also, patients with purulent meningitis had significantly higher CSF suPAR levels than patients with lymphocytic meningitis (p < 0.001). Patients with purulent meningitis who died (n = 8, 4.9 microg/l (1.3-35) had significantly higher CSF levels of suPAR than patients who survived (n = 46, 2.1 microg/l (0.1-24), Mann Whitney, p = 0.046). Employing a cut-off point of 3.1 and above, the OR (95%CI) for fatal outcome was 11.9 (1.4-106), univariate logistic regression analysis, p = 0.026. In conclusion, CSF suPAR levels may be an important predictor for fatal outcome in purulent meningitis.     

Rapid diagnosis of meningitis with use of selected clinical data and gas-liquid chromatographic determination of lactate concentration in cerebrospinal fluid.

The usefulness of determination of lactate concentration in cerebrospinal fluid (CSF) for differentiation between various types of meningitis was evaluated. Lactate concentration in the CSF was assayed by gas-liquid chromatography for 115 patients, 17 of whom had serous meningitis and 38 had bacterial meningitis. The mean lactate concentration in the CSF of patients with bacterial meningitis was significantly higher than in the CSF of patients with serous meningitis and in a control group. The mean concentration in patients with serous meningitis was significantly higher than in controls. The highest lactate level in serous meningitis overlapped with the lowest level in bacterial meningitis. Elevated lactate concentrations in CSF were found also in patients with noninfectious disorders of the central nervous system. Misleading results may therefore be obtained if the lactate concentration in CSF alone is used to distinguish between serous and bacterial meningitis. The study suggests, however, that measurements of lactate levels in CSF, when combined with clinical and conventional laboratory observations, can increase the reliability of rapid diagnosis of bacterial meningitis.     

Cerebrospinal fluid levels of IL-6 in patients with acute infections of the central nervous system.

Interleukin-6 (IL-6) activity was measured in the cerebrospinal fluid (CSF) of patients with acute bacterial or viral meningitis and in AIDS patients with various cerebral disorders. Increased levels of IL-6 were detected in the CSF of patients with bacterial meningitis. On the contrary, most of the samples from patients with viral meningitis (predominantly caused by mumps virus) had no detectable IL-6 activity in CSF. A moderate increase of IL-6 levels was detected in the CSF of AIDS patients with AIDS dementia complex (ADC), progressive multifocal leukoencephalopathy and cerebral toxoplasmosis. Moreover, higher levels of IL-6 were detected in the CSF of patients with cryptococcal meningitis. We conclude that the initial events of CSF inflammation in patients with acute viral meningitis are different from those in patients with acute bacterial meningitis, and the role of IL-6 is less critical to the process.     

Sequential bacteriological findings in the cerebrospinal fluid of Nigerian patients with pneumococcal meningitis

Sequential bacteriological observations were made on the cerebrospinal fluid (CSF) of 28 patients with pneumococcal meningitis treated with high doses of penicillin for 2 weeks. The organism was isolated from the CSF of four patients 48 h or more after the start of treatment and from a further patient 48 h after treatment was stopped. Positive cultures were obtained in spite of the demonstration in the CSF of penicillin at a concentration well above the minimum inhibitory concentration for the organism isolated. Persistence of bacteria and their products in the CSF of patients with pneumococcal meningitis contrasts with the rapid clearance of bacteria from the CSF of patients with meningococcal meningitis and may contribute to the difference in the prognosis of these forms of meningitis.     

Cerebrospinal fluid content of adenylate kinase, lactate and glutathione in patients with meningitis.

Adenylate kinase activity and lactate concentration were measured in the cerebrospinal fluid (CSF) of 5 patients with bacterial meningitis, of 4 patients with probable bacterial meningitis, and of 18 patients with serous meningitis. Furthermore, for comparison measurements were also performed in CSF of 27 patients with meningism. Concomitantly glutathione was measured in CSF in most of the patients. Significantly higher values of these 3 parameters were found in the CSF of patients with bacterial and probable bacterial meningitis compared with those having serous meningitis and meningism. Adenylate kinase activity and lactate concentration in patients with serous meningitis were significantly higher than in those with meningism. All patients with a clinical diagnosis of meningitis studied so far also displayed an adenylate kinase activity in their CSF. The determination of adenylate kinase, lactate and glutathione levels in CSF might be a useful aid for the diagnosis not only of meningitis but also for the discrimination between bacterial and serous meningitis.     

A case of bacterial meningitis due to Streptococcus bovis in an infant with normal cerebrospinal fluid findings at the first CSF examination

Streptococcus bovis very occasionally causes rarely sepsis, endocarditis, and meningitis in newborns and the elderly. We report the case of infant meningitis caused by S. bovis despite normal cerebrospinal fluid (CSF) findings at the first CSF examination. A 77-day-old boy with 21-trisomy and patent foramen ovale and seen for a high fever underwent blood examination and lumbar puncture due to toxic appearance despite a lack of meningeal signs, and was admitted. His CSF findings were normal and he was given intravenous ceftriaxone against potential bacteremia. He had systemic seizures with continuous fever for 2 days after admission and a second CSF examination. Gram-positive coccus grew from his CSF at the first examination, and CSF cells from the second lumbar puncture increased to 4060/tL (86% neutrophils), so vancomycin was added against potential enterococcal meningitis. S. bovis was finally grown from the first CSF, ceftriaxone discontinued, and intravenous ampicillin added. He recovered after 20 days of antibiotic administration. S. bovis becomes a potential pathogen for meningitis in infants, and must be considered as a cause of meningitis despite its very rarity. CSF findings at the first lumbar puncture may be normal for meningitis in newborns and infants at the first CSF examination, so we must be very careful in the diagnosis of bacterial meningitis even with normal CSF findings, and considered antibiotic treatment against potential bacterial meningitis.     

Vascular endothelial growth factor in bacterial meningitis: detection in cerebrospinal fluid and localization in postmortem brain

Vascular endothelial growth factor (VEGF) is a potent vascular permeability factor and a mediator of brain edema. To assess the role of VEGF during bacterial meningitis, VEGF was measured in cerebrospinal fluid (CSF) and blood of 37 patients with bacterial meningitis and 51 control patients, including 16 patients with viral meningitis. Circulating VEGF levels were similar in bacterial meningitis patients and control patients. VEGF(CSF) was detected in 11 (30%) of 37 of bacterial meningitis patients (range, <25-633 pg/mL) but in none of the control patients. The median VEGF index was 6.2 (range, 0.6-42), indicating intrathecal production. Median CSF cell counts, protein levels, and CSF: serum albumin ratios were higher for patients with detectable VEGF(CSF), although the difference was not statistically significant. VEGF immunoreactivity in autopsy brain specimens was found in the inflammatory infiltrate of patients with bacterial meningitis. These results indicate that inflammatory cells secrete VEGF during bacterial meningitis and that VEGF may contribute to blood-brain barrier disruption.     

The role of the polymerase chain reaction in the diagnosis of bacterial meningitis in Vietnam

Bacterial meningitis remains an important cause of morbidity and mortality in Vietnam. Diagnosis is hampered by the ready availability of antibiotics in the community, leading to late presentation, masked clinical signs, and poor organism detection during the microscopical examination and culture of cerebrospinal fluid (CSF). In order to improve organism detection at the Hospital for Tropical Diseases in Ho Chi Minh City, a diagnostic PCR-based protocol was developed. This protocol was followed in the investigation of CSF samples from 36 patients with clinical signs of bacterial meningitis. Each sample was first tested in a semi-nested PCR using primers for the 16sRNA gene common to all bacteria. The products of this reaction were then amplified using a 16sru8 primer and primers specific for Neisseria meningitidis, Haemophilus influenzae or Streptococcus spp. The samples found positive for Streptococcus were further investigated in a nested PCR using primers specific for the pneumolysin gene of S. pneumoniae. The sensitivity of detection was increased from 36% with culture to 44% with PCR. Although the sample size was small, the results indicate that PCR would be a feasible and useful adjunct in the diagnosis of bacterial meningitis, particularly in areas where community antibiotic use is common.     

Significance of Histoplasma antigen in the cerebrospinal fluid of patients with meningitis

A radioimmunoassay was previously developed for detection of Histoplasma capsulatum antigen in the blood and urine of patients with disseminated histoplasmosis. In this investigation, cerebrospinal fluid (CSF) specimens from 14 episodes of Histoplasma meningitis occurring in 12 patients were tested by radioimmunoassay. Histoplasma capsulatum antigen was detected in the CSF of five patients. Cerebrospinal fluid cultures were positive for H capsulatum in three of these five patients. Antibodies to H capsulatum were found in nine of the 13 CSF specimens tested. The radioimmunoassay for Histoplasma antigen was also positive in the CSF in one of 11 patients with coccidioidal meningitis but not in 17 patients with cryptococcal meningitis. It was concluded that Histoplasma antigen is present in the CSF of some patients with histoplasmosis and chronic meningitis, but cross-reactions may occur in patients with coccidioidal meningitis.     

High sensitivity and specificity of serum procalcitonin levels in adults with bacterial meningitis.

It was shown in children that serum procalcitonin was the best marker to use to differentiate bacterial from viral meningitis. To evaluate procalcitonin in the diagnosis of acute bacterial and viral meningitis, we conducted a prospective study including adult patients who were suspected of having meningitis and who were admitted to an emergency department. Cerebrospinal fluid (CSF) and serum levels of procalcitonin were measured in 105 consecutive patients. The diagnosis of meningitis was based on clinical findings, gram staining, culture, and chemical analysis of CSF. Twenty-three patients had bacterial meningitis, 57 had viral meningitis, and 25 did not have meningitis. Bacteriologic and chemical analysis of CSF did not allow correct differentiation of viral from bacterial meningitis. On the other hand, a serum procalcitonin level >0.2 ng/mL had a sensitivity and specificity of up to 100% in the diagnosis of bacterial meningitis. Serum procalcitonin levels seem to be the best marker in differentiating between bacterial and viral meningitis in adults.     

Association of matrix metalloproteinase-9 and tissue inhibitors of metalloproteinase-4 in cerebrospinal fluid with blood-brain barrier dysfunction in patients with eosinophilic meningitis caused by Angiostrongylus cantonensis

To evaluate possible blood-brain barrier (BBB) dysfunction caused by matrix metalloproteinase-9 (MMP-9) and its regulation by tissue inhibitors of metalloproteinase (TIMPs) in patients with eosinophilic meningitis caused by infection with Angiostrongylus cantonensis, 40 patients and 28 controls were included in this study. Concentrations of MMP-2, MMP-9, TIMP-1, and cerebrospinal fluid (CSF):serum albumin ratios (Q(Alb) values) were significantly increased in patients compared with controls. However, concentrations of TIMP-4 were significantly lower in patients. In contrast to MMP-2, proteolytic activity of MMP-9 detected by gelatin zymography was only observed in patients with eosinophilic meningitis. We detected higher levels of antibodies specific for A. cantonensis and higher Q(Alb) values and MMP-9 concentrations in CSF of patients with eosinophilic meningitis, Furthermore, the increase in the Q(Alb) value was significantly correlated with the increase in MMP-9 in patients. In parallel with CSF MMP-9, patients also showed an increase in CSF leukocyte counts. Gradual decreases in levels of Q(Alb), MMP-9, and TIMP-1 and increases in levels of TIMP-4 were observed in six patients during recovery from eosinophilic meningitis. These results suggest that the source of MMP-9 in CSF of patients with eosinophilic meningitis was probably associated with leukocytes migrating from peripheral blood to CSF. Activity of MMP-9 in CSF of patients could not be completely inhibited because of the decrease of TIMP-4, which may cause BBB dysfunction, as shown by higher Q(Alb) values in patients.     

General principles of therapy of pyogenic meningitis

In bacterial meningitis, several pharmacodynamic factors determine therapeutic success-when defined as sterilization of the CSF: (1) Local host defense deficits in the CNS require the use of bactericidal antibiotics to sterilize the CSF. (2) CSF antibiotic concentrations that are at least 10-fold above the MBC are necessary for maximal bactericidal activity. Protein binding, low pH, and slow bacterial growth rates are among the factors that may explain the high antibiotic concentrations necessary in vivo. (3) High CSF peak concentrations that lead to rapid bacterial killing appear more important than prolonged suprainhibitory concentrations, probably because very low residual levels in the CSF prevent bacterial regrowth, even during relatively long dosing intervals. (4) Penetration of antibiotics into the CSF is significantly impaired by the blood-brain barrier and thus, very high serum levels are necessary to achieve the CSF concentrations required for optimal bactericidal activity. Beyond these principles, recent data suggests that rapid lytic killing of bacteria in the CSF may have harmful effects on the brain because of the release of biologically active products from the lysed bacteria. Since rapid CSF sterilization remains a key therapeutic goal, the harmful consequences of bacterial lysis present a major challenge in the therapy of bacterial meningitis. Currently, dexamethasone represents that only clinically beneficial approach to reduce the harmful effects of bacterial lysis, and novel approaches are required to improve the outcome of this serious infection.     

Tuberculous meningitis with acellular cerebrospinal fluid in AIDS patients.

OBJECTIVE: To describe the clinical manifestations of tuberculous meningitis in HIV-positive patients with acellular cerebrospinal fluid (CSF). DESIGN: Retrospective analysis of case reports. METHODS: Four HIV-positive patients with acellular CSF and tuberculous meningitis are reported. RESULTS: Clinical presentation did not indicate meningeal infection in three of the four cases, and CSF tests were unusual in all cases. Two patients were diagnosed only after death. CONCLUSIONS: Acellular CSF may obstruct the diagnosis of tuberculous meningitis in AIDS patients.     

Failure of treatment for chronic Mycobacterium abscessus meningitis despite adequate clarithromycin levels in cerebrospinal fluid.

We report a case of posttraumatic meningitis due to Mycobacterium abscessus, treated initially with oral clarithromycin and intravenous amikacin plus intrathecal amikacin. Despite cerebrospinal fluid (CSF) levels of clarithromycin and amikacin in excess of their in vitro minimum inhibitory concentrations for the organism, the CSF cultures remained continuously positive for M. abscessus. To our knowledge, this is the first documented case of M. abscessus meningitis and the first report of measured CSF levels of clarithromycin in a patient with meningitis, showing that even therapeutic CSF levels of clarithromycin and amikacin might not be successful in eradicating M. abscessus meningitis.     

脑脊液miRNA-22水平对儿童细菌性脑膜炎的早期诊断及疗效分析

目的研究脑脊液miRNA-22用于早期诊断儿童化脓性脑膜炎及其治疗效果预测的临床价值。 方法选取佛山市南海区妇幼保健院自2015年1月至2018年3月收治的82例脑膜炎患儿和佛山市第二人民医院同期收治的44例脑膜炎患儿,根据确诊病因类型分为细菌性脑膜炎组（n=64）、病毒性脑膜炎组（n=44）、结核性脑膜炎组（n=18）。比较3组患儿治疗前和治疗后脑脊液miRNA-22拷贝数差异。常规标准治疗下将细菌性脑膜炎患儿治疗效果情况分为满意（28例）、一般（19例）、欠佳（17例）,比较不同治疗效果下在入院时、治疗后第1、3、5天时脑脊液miRNA-22水平差异以评价其水平、变化趋势以及与疾病治疗效果的关系。 结果相较于病毒性脑膜炎组和结核性脑膜炎组,细菌性脑膜炎组治疗前miRNA-22的拷贝数明显更高,差异具有统计学意义（P<0.05）。细菌性脑膜炎组经过治疗后,脑脊液miRNA-22的水平呈现快速下降的趋势,差异具有统计学意义（P<0.05）。细菌性脑膜炎组患儿入院时脑脊液miRNA-22水平差异无统计学意义（P>0.05）,但疗效越差患儿入院时miRNA的水平更高;治疗效果满意的细菌性脑膜炎患儿的脑脊液miRNA-22拷贝数明显较疗效一般和欠佳的患儿更低,差异具有统计学意义（P<0.05）。 结论脑膜炎患儿脑脊液中miRNA-22拷贝数的水平对早期区分脑膜炎病原菌的类型有一定的参考价值,细菌性脑膜炎患儿脑脊液中的miRNA-22拷贝数明显升高,且miRNA-22拷贝数与细菌性脑膜炎患儿的预期治疗效果有关。     

Influence of granulocytes on brain edema, intracranial pressure, and cerebrospinal fluid concentrations of lactate and protein in experimental meningitis

Brain water content (brain edema), intracranial pressure, and cerebrospinal fluid (CSF) concentrations of lactate and protein increased significantly during 24 h of experimental meningitis due to Streptococcus pneumoniae, but changes were similar in normal and neutropenic rabbits. In sterile meningitis induced by N-formyl-methionyl-leucyl-phenyl-alanine (fMLP), low and high doses of fMLP were equally effective in inducing CSF pleocytosis, whereas only high doses of fMLP caused brain edema. High doses of fMLP injected intracisternally during pneumococcal meningitis also increased brain water content. The fMLP did not significantly increase intracranial pressure or CSF concentrations of lactate or protein in sterile or pneumococcal meningitis, nor did it cause brain edema in neutropenic animals. Thus, granulocytes may contribute to brain edema during meningitis if adequately stimulated, but intracranial pressure and CSF protein and lactate concentrations appear independent of granulocytes. Stimulation does not appear to occur early in meningitis, when granulocytes were without effect on brain edema.     

Blood-brain barrier damage in patients with bacterial meningitis: association with tumor necrosis factor-alpha but not interleukin-1 beta.

Brain damage after meningeal infection could result from impairment of cerebral endothelial cell functions and disruption of blood-brain barriers. Tumor necrosis factor-alpha (TNF alpha) and interleukin-1 beta (IL-1 beta) produce many of their effects by acting on endothelial cells. This study correlates levels of TNF alpha and IL-1 beta in paired cerebrospinal fluid (CSF) and serum samples with the degree of blood-brain barrier damage, as manifested by CSF to serum albumin quotient, in 48 patients with bacterial meningitis and 66 controls. CSF levels of TNF alpha and IL-1 beta in bacterial meningitis were significantly higher than in controls. Intrathecal levels of TNF alpha, but not IL-1 beta, correlated with albumin quotient (P less than .001), with degree of blood-brain barrier disruption (P less than .001), and with disease severity and indices of meningeal inflammation. Sequential CSF samples demonstrated that IL-1 beta and TNF alpha disappear from the CSF within 24 h of antibiotic treatment. Data presented here suggest that TNF alpha is related to blood-brain barrier damage in bacterial meningitis and that its effect could be dissociated from that of IL-1 beta.     

结核性脑膜炎患者血清及脑脊液中sTRAIL、OPG水平测定及其临床意义

目的 探讨结核性脑膜炎患者肿瘤坏死因子相关凋亡诱导配体（TRAIL）及其受体骨保护素（OPG）在血清及脑脊液中的水平变化并探讨其临床意义.方法 采用ELISA法检测30例结核性脑膜炎患者（结脑组）急性期和20例对照组的血清及脑脊液中TRAIL和OPG的水平,并分析其与病情严重程度的关系.结果 急性期结脑患者血清TRAIL、OPG水平较对照组明显升高,差异有显著性（P＜0.05）,重症组患者血清TRAIL、OPG水平与轻症组比较明显升高,差异有显著性（P＜0.05）;脑脊液中的TRAIL、OPG水平与对照组比较明显升高,差异有显著性（P＜0.05）.结论 TRAIL及其受体OPG可能参与了结核性脑膜炎的病理过程,且其水平的高低与病情的轻重程度有关.     

Measurement of lactic acid in cerebrospinal fluid of patients with infections of the central nervous system

The concentration of lactic acid in cerebrospinal fluid (CSF) was determined by gas-liquid chromatography in 205 samples of CSF from 97 patients with or without infections of the central nervous system. Patients without infection or those with nonbacterial (presumably viral) meningitis consistently had low concentrations of lactic acid in CSF (i.e., less than or equal to 35 mg/100 ml), whereas patients with bacterial or tuberculosis meningitis consistently had concentrations of lactic acid in CSF of greater than 35 mg/100 ml. There was no overlap in concentrations of lactic acid between these two groups. Further, lactic acid concentrations in CSF from patients partially treated for meningitis were generally greater than 35 mg/100 ml through the third day of therapy and, thereafter, progressively declined to less than 20 mg/100 ml by the seventh to 10th day of therapy. Relapse of bacterial infection was consistently documented by a recurrence of an increased concentration of lactic acid in CSF. Preliminary experience with determination of the concentration of lactic acid in CSF suggests that it may be useful in distinguishing bacterial (with or without positive cultures) and tuberculous meningitis from meningitis due to nonbacterial causes.