Klebsiella meningitis in adults: clinical features, prognostic factors and therapeutic outcomes

Meningitis caused by Aeromonas hydrophila in Oreochromis niloticus: Proteomics and druggability of virulence factors

Meningitis caused by Gram-negative bacteria is a serious public health problem, causing morbidity and mortality in both children and adults. Here, we propose a novel experimental model using Nile tilapia (Oreochromis niloticus) to study neuroinflammation. The fish were infected with Aeromonas hydrophila, and the course of infection was monitored in the peripheral blood. Septicemia was obvious in the blood, while in the brain tissue, infection of the meninges was present. The histopathological examination showed suppurative meningitis, and the cellular immune response in the brain tissue during infection was mediated by microglia. These cells were morphologically characterized and phenotyped by MHC class II markers and CD68. The increased production of TNF-α, IL-1β and iNOS supported the infiltration of these cells during the neuroinflammatory process. In the proteomic analysis of A. hydrophila isolated from brain tissue, we found chemotactic and transport proteins, proteolytic enzymes and enzymes associated with the dismutation of nitric oxide (NO), as well as motor proteins and those responsible for cell division. After characterizing the most abundant proteins during the course of infection, we investigated the druggability index of these proteins and identified promising peptide sequences as molecular targets that are similar among bacteria. Thus, these findings deepened the understanding of the pathophysiology of meningitis caused by A. hydrophila. Moreover, through the proteomics analysis, important mechanisms and pathways used by the pathogen to subvert the host response were revealed, providing insights for the development of novel antibiotics and vaccines.

Clinical characteristics and prognosis of Klebsiella pneumoniae meningitis in adults

Background

Klebsiella pneumoniae is a causative agent of bacterial meningitis in adults. However, there is little information regarding this infection. Therefore, this study comprehensively analyzed the clinical characteristics and prognosis of Klebsiella pneumoniae meningitis (KPM) patients.

Methods

The clinical data of adult hospitalized patients with KPM were retrospectively collected from January 2015 to December 2022. The clinical characteristics and antibiotic resistance of KPM were evaluated. Meanwhile, a set of logistic regression models was constructed to identify prognostic factors for death. These prognostic factors were subsequently combined to develop a nomogram for predicting the risk of in-hospital mortality in individual patients. Finally, the receiver operating characteristic curve and calibrate plot were utilized to verify the performance of the nomogram.

Results

This study included 80 adult patients with KPM, 58 (72.5%) of whom were males. The mortality rate was 45%. Among them, 74 (92.5%) were diagnosed with healthcare-associated meningitis. Thirty-seven carbapenem-resistant Klebsiella pneumoniae (CRKP) strains were susceptible to tigecycline, polymyxin, and ceftazidime/avibactam. CRKP (OR = 9.825, 95%CI = 2.757-35.011, P < 0.001), length of stay (OR = 0.953, 95%CI = 0.921-0.986, P = 0.005), and C-reactive protein-to-prealbumin ratio (CRP/PA, OR = 3.053, 95%CI = 1.329-7.016, P = 0.009) were identified as predictive factors for mortality using multivariate logistic regression. Finally, a nomogram for death prediction was established. The area under the curve of this nomogram was 0.900 (95% CI = 0.828-0.971).

Conclusions

KPM is a fatal disease associated with high incidence of healthcare-associated infections and carbapenem resistance. Moreover, CRKP, length of stay, and CRP/PA were found to be independent predictors of mortality.

The clinical characteristics and therapeutic outcomes of adult patients with community-acquired spontaneous bacterial meningitis with a fulminant clinical course in Taiwan

PURPOSE

To examine the clinical characteristics of adult patients with community-acquired spontaneous bacterial meningitis (CASBM) with a fulminant clinical course.

MATERIALS AND METHODS

The clinical features and therapeutic outcomes of 127 adult CASBM patients were analyzed. The patients were divided into two groups as those with and without a fulminant clinical course. Fulminant clinical course was defined as meningitis presenting initially with marked consciousness disturbance (Glasgow Coma Scale score < 8) or a rapid deterioration in consciousness level within 48 h of hospitalization.

RESULTS

Among the 127 enrolled patients, 69 had a fulminant clinical course (47 men and 22 women) and 58 did not. The patients with a fulminant clinical course had a significantly higher incidence of end-stage renal disease (ESRD), severe clinical manifestations and higher mortality rate, and the survivors had significantly worse therapeutic outcomes. Klebsiella (K.) pneumoniae (50 strains) was the most important pathogen for the development of a fulminant clinical course, and all strains were susceptible to ceftriaxone and ceftazidime. With treatment, 50.7% (35/69) of the patients with a fulminant clinical course died, and the presence of K. pneumoniae infection was significant prognostic factor.

CONCLUSIONS

The presence of ESRD, initial presentation of altered consciousness, septic shock, seizures and CSF total protein level and K. pneumoniae infection were significantly associated with a fulminant clinical course of adult CASBM, and patients with this specific infectious syndrome had high mortality and morbidity rates. The presence of K. pneumoniae infection is a significant prognostic factor.

Determination of Klebsiella pneumoniae Susceptibility to Antibiotics Using Infrared Microscopy

Klebsiella pneumoniae (K. pneumoniae) is one of the most aggressive multidrug-resistant bacteria associated with human infections, resulting in high mortality and morbidity. We obtained 1190 K. pneumoniae isolates from different patients with urinary tract infections. The isolates were measured to determine their susceptibility regarding nine specific antibiotics. This study's primary goal is to evaluate the potential of infrared spectroscopy in tandem with machine learning to assess the susceptibility of K. pneumoniae within approximately 20 min following the first culture. Our results confirm that it was possible to classify the isolates into sensitive and resistant with a success rate higher than 80% for the tested antibiotics. These results prove the promising potential of infrared spectroscopy as a powerful method for a K. pneumoniae susceptibility test.

Sex-based differences in bacterial meningitis in adults: Epidemiology, clinical features, and therapeutic outcomes

BACKGROUND

To investigate the sex-based differences in clinical features, causative pathogens, and outcomes of hospital-based culture-proven adult bacterial meningitis.

OBJECTIVE

This retrospective study enrolled 621 patients at a tertiary medical center. To compare changes over time, the presentation of disease among the enrolled patients was divided into two equal time periods: the first study period (1986-2002) and the second study period (2003-2019).

RESULTS

Of the 621 patients enrolled in this study, 396 were males and 225 were females. The overall case fatality rate was 30.4% with 30.1% and 31.1% in males and females, respectively. Regarding the causative pathogens, there was a rising incidence of coagulase-negative staphylococcal infections and a decreasing incidence of Klebsiella pneumoniae infection in both male and female in the second study period. The prevalence of patients with nosocomial infection in a postneurosurgical state were 41.9% (68/162) in the first study period and 58.1% (94/162) in the second study period in male group, and 34.8% (32/92) in the first study period and 65.2% (60/92) in the second study period in female group, respectively. Significant factors between the sexes difference included age (P = 0.004), traumatic brain injury (P = 0.01), alcoholism (P < 0.001), brain tumor (P < 0.001), systemic lupus erythematosus (SLE) (P = 0.004), presence of diabetic ketoacidosis/hyperglycemic hyperosmolar state (P = 0.033), brain abscess (P = 0.042), and total protein (P = 0.002) and white blood cell count (P = 0.036) of cerebrospinal fluid data.

CONCLUSION

Our study revealed an increase in the number of patients with nosocomial infection with a postneurosurgical state in both male and female in the second study period. Males were younger and frequently presented with a history of head trauma and alcoholism with concomitant brain abscesses while females presented with SLE and brain tumor. The therapeutic outcome did not show differences between the sexes.

Epidemiology and clinical characteristics of Klebsiella spp. meningitis in France

OBJECTIVES

To describe the epidemiology of Klebsiella spp. meningitis in France with respect to clinical and bacteriological data.

METHODS

We performed a four-year multicenter, retrospective, observational study. The primary objective was to provide a clinical description of patients with Klebsiella spp. meningitis. Secondary objectives were to compare community-acquired meningitis and healthcare-associated meningitis and to analyze factors associated with mortality.

RESULTS

We enrolled 131 patients with Klebsiella spp. meningitis. Eighty-two (62.6%) infections were reported following neurosurgery. Twenty-eight strains (21.4%) were resistant to third-generation cephalosporins (3GC). The median [IQR] cellularity was 980/mm³ [116-5,550], the median protein level was 5.67 [1.62-9] g/L and the median CSF glucose level was 2.5 [0-3.4] mmol/L. The in-hospital mortality rate was 23.6%. Community-acquired meningitis isolates were more frequently susceptible to 3GC than isolates from healthcare-associated meningitis (89.2% versus 72%; p=0.04). Comorbidities reported for patients with community-acquired meningitis were mainly diabetes mellitus and liver cirrhosis. In multivariate analysis, focal neurological disorder at the time of diagnosis was the only factor associated with in-hospital mortality (p=0.01).

CONCLUSIONS

Purulent meningitis caused by Klebsiella spp. needs to be considered in patients with community-acquired meningitis and pre-existing conditions, as well as in case of meningitis following neurosurgical procedures.

Outcomes of adjunctive steroid therapy in adult patients with bacterial meningitis in Taiwan: A nationwide population-based epidemiologic study

BACKGROUND

Although corticosteroids are an effective anti-inflammatory adjuvant therapy, the role of adjunctive steroid therapy in treating adult bacterial meningitis in Taiwan remains controversial.

METHODS

Cases of acute bacterial meningitis were identified from the annual hospitalization discharge claims of the National Health Insurance Research Database using International Classification of Diseases, Ninth Revision codes from January 2000 to December 2013. Patients were classified into two groups: (1) steroid group (adjunctive steroids and empirical antibiotics) and (2) placebo group (empirical antibiotics only).

RESULTS

There were 15,037 patients enrolled in this study; of these, 57% (7175/15,037) and 52% (7862/15,037) were placed in the placebo and steroid groups, respectively. The case-fatality rates were 11.5% (826/7175) in the placebo group and 19.9% (1562/7862) in the steroid groups during hospitalization (P = 0.77). Further, the hazard ratio (relative to placebo group) of in-hospital and one-year case fatality rate were 0.923 (95% confidence interval [CI]: 0.846-1.007, P = 0.073) and 1.514 (95% CI: 1.425-1.608, P < 0.0001) according to the multivariate Cox model after adjustment for age and sex.

CONCLUSION

On the basis of these results, steroid group had a more fulminant clinical course (e.g., acute respiratory failure and pneumonia, etc.), and unfavorable outcomes than placebo group. Therefore, more prospective, randomized, double-blind trials are warranted to evaluate the efficacy of adjunctive steroid therapy in treating adult bacterial meningitis in Taiwan.

Klebsiella pneumoniae invasive liver abscess syndrome with purulent meningitis and septic shock: A case from mainland China

We present a rare case of invasive liver abscess syndrome due to Klebsiella pneumoniae (K. pneumoniae) with metastatic meningitis and septic shock. A previously healthy, 55-year-old female patient developed fever, liver abscess, septic shock, purulent meningitis and metastatic hydrocephalus. Upon admission, the clinical manifestations, laboratory and imaging examinations were compatible with a diagnosis of K. pneumoniae primary liver abscess. Her distal metastasis infection involved meningitis and hydrocephalus, which could flare abruptly and be life threatening. Even with early adequate drainage and antibiotic therapy, the patient’s condition deteriorated and she ultimately died. To the best of our knowledge, this is the first case of K. pneumoniae invasive liver abscess syndrome with septic meningitis reported in mainland China. Our findings reflect the need for a better understanding of the epidemiology, risk factors, complications, comorbid medical conditions and treatment of this disease.

Klebsiella variicola is a frequent cause of bloodstream infection in the stockholm area, and associated with higher mortality compared to K. pneumoniae

Clinical isolates of Klebsiella pneumoniae are divided into three phylogroups and differ in their virulence factor contents. The aim of this study was to determine an association between phylogroup, virulence factors and mortality following bloodstream infection (BSI) caused by Klebsiella pneumoniae. Isolates from all adult patients with BSI caused by K. pneumoniae admitted to Karolinska University Hospital, Solna between 2007 and 2009 (n = 139) were included in the study. Phylogenetic analysis was performed based on multilocus sequence typing (MLST) data. Testing for mucoid phenotype, multiplex PCR determining serotypes K1, K2, K5, K20, K54 and K57, and testing for virulence factors connected to more severe disease in previous studies, was also performed. Data was retrieved from medical records including age, sex, comorbidity, central and urinary catheters, time to adequate treatment, hospital-acquired infection, and mortality, to identify risk factors. The primary end-point was 30- day mortality. The three K. pneumoniae phylogroups were represented: KpI (n = 96), KpII (corresponding to K. quasipneumoniae, n = 9) and KpIII (corresponding to K. variicola, n = 34). Phylogroups were not significantly different in baseline characteristics. Overall, the 30-day mortality was 24/139 (17.3%). Isolates belonging to KpIII were associated with the highest 30-day mortality (10/34 cases, 29.4%), whereas KpI isolates were associated with mortality in 13/96 cases (13.5%). This difference was significant both in univariate statistical analysis (P = 0.037) and in multivariate analysis adjusting for age and comorbidity (OR 3.03 (95% CI: 1.10–8.36). Only three of the isolates causing mortality within 30 days belonged to any of the virulent serotypes (K54, n = 1), had a mucoid phenotype (n = 1) and/or contained virulence genes (wcaG n = 1 and wcaG/allS n = 1). In conclusion, the results indicate higher mortality among patients infected with isolates belonging to K. variicola. The increased mortality could not be related to any known virulence factors, including virulent capsular types or mucoid phenotype.

Spontaneous adult Gram-negative bacillary meningitis in Soweto, South Africa

BACKGROUND

Gram-negative bacillary (GNB) meningitis is a rare cause of meningitis in adults and can occur as a spontaneous infection or as a complication of a neurosurgical procedure or trauma. We aimed to describe the characteristics and outcomes of adults with spontaneous GNB meningitis.

METHODS

A retrospective cohort analysis was performed of 26 patients with GNB meningitis seen at a single hospital in Soweto, South Africa.

RESULTS

A predisposing condition was found in 24 (92%) patients. The 19 (73%) HIV-infected patients had a median CD4 count of 24/mm(3). Chronic renal disease, diabetes mellitus, myeloma, and alcoholism were other underlying conditions. The HIV-infected had a median cerebrospinal fluid (CSF) neutrophil count of 2/mm(3) compared to the HIV-non-infected of 560/mm(3). Common organisms were Escherichia coli, Klebsiella pneumoniae, and non-typhoidal Salmonella in HIV-positive patients and K. pneumoniae in the HIV-negative group. Ten (38%) isolates were resistant to third-generation cephalosporins. Mortality was 65%.

CONCLUSIONS

A disproportionate burden of GNB meningitis fell on the HIV-infected, among whom absent or low CSF white cells was common. Management was complicated by high rates of resistance to third-generation cephalosporins.

Importance of Early Cranioplasty in Reversing the "Syndrome of the Trephine/Motor Trephine Syndrome/Sinking Skin Flap Syndrome"

INTRODUCTION

The "Motor Trephine Syndrome (MTS)" also known as the "Sunken brain and Scalp Flap Syndrome" or the "Sinking Skin Flap Syndrome (SSFS)" or the "Syndrome of the trephined" is an unusual syndrome in which neurological deterioration occurs following removal of a large skull bone flap. This syndrome is associated with sensorimotor deficit and neurological deterioration following decompressive craniectomy which is performed for various neurosurgical conditions involving cerebral swelling causing mass effect. The neurological deterioration can be exacerbated or precipitated by CSF diversion procedures like a Ventriculo-Peritoneal shunt.

OBJECTIVE

It was the objective of this study to observe if any improvement in the patient's condition, or if any beneficial effects in his sensorimotor deficit could be gained by performing an early cranioplasty as against after the usual delay of one to two years normally allowed for post-craniectomy cases.

METHODS

A 52 year old male suffered severe head injury in a road traffic accident and underwent a craniectomy and contusectomy of the left Fronto-Temporo-Parietal (FTP) region for treatment of Acute Subdural hematoma (SDH) as well as hemorrhagic and non-hemorrhagic contusions of the brain with severe mass effect. On recovery from this acute event he was bed bound, on tracheostomy, his GCS was E4VTrM4 with residual right sided hemiparesis. Three months later, he developed Hydrocephalus for which a Right Ventriculo-Peritoneal (V-P) shunt was performed. Following this procedure, severe depression of the skin/scalp flap occurred and the neurological recovery was not as expected. He was diagnosed as a case of "Syndrome of the trephined". An immediate Cranioplasty was performed, on the third month following the craniectomy procedure, in an attempt to resolve the rapidly deteriorating neurological status of the patient.

RESULTS

In the case presented, following the early Cranioplasty which was performed within three months of the initial craniectomy, the patient's neurological condition and cognitive functions showed a remarkable, immediate and dramatic improvement. The early Cranioplastic repair led to a remarkable clinical recovery of the patient, with improvement in the cognitive behavior and motor deficit with a rapid reversal of the sensorimotor paresis, reflecting an improvement in brain perfusion.

CONCLUSION

Patients with the classical "Motor trephine syndrome/ Sinking skin flap syndrome" following large craniectomy defects, may hugely benefit from an early cranioplasty procedure, with a reversal of features of this syndrome and early recovery of their neurological and cognitive functions. Hence, an early cranioplasty can serve as a therapeutic procedure, rather than merely a cosmetic one.

Intracranial malignant lesions correlate with the requirement for a long treatment course in postoperative central nervous system infection

AIM

Our aim was to study the clinical features of postoperative meningitis after neurosurgery and identify the factors affecting the duration of treatment.

METHODS

This retrospective study assessed 283 patients with postoperative bacterial meningitis in the Neurosurgery Department of Beijing Tiantan Hospital, Beijing, People's Republic of China, between January and December 2012. Patients' clinical data were reviewed, and multivariate logistic regression analysis was used to identify the factors associated with a prolonged treatment course.

RESULTS

The mortality rate was 0.4% in these patients, of whom 12.4% were found with pathogens in the cerebrospinal fluid. Among the three most common pathogens detected were methicillin-resistant Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa. The mean treatment course was 13.5±2.1 days. Interestingly, the treatment duration for postoperative meningitis was significantly longer in patients with intracranial malignant tumors than in those with benign lesions. Single-factor analysis showed that male sex (P=0.042) and malignant (rather than benign) lesions (P<0.001) were significantly associated with prolonged treatment duration. Multivariate analysis further confirmed that malignant intracranial lesions represented an independent risk factor for prolonged treatment duration (odds ratio: 2.5962; 95% confidence interval: 1.1092-6.6134).

CONCLUSION

The nature of the intracranial lesion is an independent risk factor for the duration of treatment in postoperative meningitis after neurosurgery.

Klebsiella pneumoniae meningitis induces memory impairment and increases pro-inflammatory host response in the central nervous system of Wistar rats

Klebsiella pneumoniae meningitis has recently become an increasingly common cause of central nervous system infection. The invasion of bacteria within the subarachnoid space stimulates the release of pro-inflammatory cytokines and chemokines, triggering a host immune response. The aim of the present study was to evaluate memory and pro-inflammatory mediators at different times in the brains of adult Wistar rats with K. pneumoniae meningitis. The animals were sacrificed at 6, 12, 24, 48 and 96 h after meningitis induction. The hippocampus, frontal cortex and cerebrospinal fluid were isolated to determine the cytokine, chemokine and brain-derived neurotrophic factor (BDNF) levels. In the first 6 and 24 h following meningitis induction, there was a significant increase of the TNF-α, IL-1β, IL-6, cytokine-induced neutrophil chemoattractant-1 and BDNF levels in the central nervous system. Ten days after meningitis induction, cognitive memory was evaluated using an open-field task and step-down inhibitory avoidance task. In the control group, significant differences in behaviour were observed between the training and testing sessions for both tasks, demonstrating habituation and aversive memory. However, the meningitis group did not exhibit any difference between the training and testing sessions in either task, demonstrating memory impairment. As a result of these observations, we believe that the meningitis model may be a good research tool to study the biological mechanisms involved in the pathophysiology of this illness, while recognizing that animal models should be interpreted with caution before extrapolation to the clinic.

Evaluation of energetic metabolism in the rat brain after meningitis induction by Klebsiella pneumoniae

BACKGROUND

Bacterial meningitis is an infection of the central nervous system characterised by strong inflammatory response. The brain is highly dependent on ATP, and the cell energy is obtained through oxidative phosphorylation, a process which requires the action of various respiratory enzyme complexes and creatine kinase (CK) as an effective buffering system of cellular ATP levels in tissues that consume high energy.

OBJECTIVES

Evaluate the activities of mitochondrial respiratory chain complexes I, II, III, IV and CK activity in hippocampus and cortex of the Wistar rat submitted to meningitis by Klebsiella pneumoniae.

METHODS

Adult Wistar rats received either 10 µl of sterile saline as a placebo or an equivalent volume of K. pneumoniae suspension. The animals were killed in different times at 6, 12, 24 and 48 h after meningitis induction. Another group was treated with antibiotic, starting at 16 h and continuing daily until their decapitation at 24 and 48 h after induction.

RESULTS

In the hippocampus, the meningitis group without antibiotic treatment, the complex I was increased at 24 and 48 h, complex II was increased at 48 h, complex III was inhibited at 6, 12, 24 and 48 h and in complex IV all groups with or without antibiotic treatment were inhibited after meningitis induction, in the cortex there was no alteration. Discussion Although descriptive, our results show that antibiotic prevented in part the changes of the mitochondrial respiratory chain. The meningitis model could be a good research tool to study the biological mechanisms involved in the pathophysiology of the K. pneumoniae meningitis.

Nosocomial meningitis caused by gas producing Klebsiella pneumoniae

A 40-year-old woman presented with dyspnoea and lowered level of consciousness. Three months before presentation she had underwent craniotomy for an episode of acute subdural hematoma caused by a severe neurotrauma. Her temperature was 37.3°C, she had no focal neurological deficits or neck stiffness, and the score on the Glasgow Coma Scale was 9 (E2M5V2). Cranial CT showed obstruction hydrocephalus with hypodensities consistent with airbubbles in the lateral ventricles, but no air in the proximity of the skull defect resulting from the craniotomy. External ventricular drainage was performed and cerebrospinal fluid (CSF) examination showed 126 327 leucocytes per μl, a protein level of 26.28 g/l and a glucose level of <0.1 mmol/l. CSF culture grew Klebsiella pneumoniae, a gas producing bacterium. Despite antibiotic treatment with meropenem, ceftriaxone and intraventricular gentamicin and supportive therapy, our patient deteriorated and died 3 weeks after admission. The family did not give consent for autopsy.

The experiences of non-operative treatment in patients with bacterial brain abscess

Although treatment of brain abscess requires a combination of antimicrobials and surgical intervention for the infected foci, nonsurgical, empirical treatment is possible and efficient in selected groups of patients. A total of 31 patients were enrolled in this 22-year retrospective study. We describe our therapeutic experiences and attempt to analyze the risk factors that were predictive of therapeutic outcomes. Multiple logistic regression was used to evaluate the relationships between baseline clinical factors and therapeutic outcome during the study period. Of these 31 patients, 25 had community-acquired infections, whereas the other six had nosocomially-acquired infections. Thirteen cases (42%) had a single brain abscess and the other 18 cases (58%) had multiple brain abscesses. Furthermore, the association of bacterial meningitis and brain abscess was found in 81% (25/31) of cases. The overall case fatality rate was 48% (15/31). Significant risk factors for poor outcomes included Glasgow coma scale (GCS) at presentation, presence of septic shock and neck stiffness. In addition, each reduction of one point on the GCS increased the poor outcome rate by 28%. The findings of the study demonstrate that both a higher mortality rate (48%) and worse outcomes were found in this select group of patients. Among the significant prognostic factors, a lower mean GCS at presentation was a major determinant of poor outcome.

Appropriateness is critical

Inappropriate empirical antibiotic therapy for severe infections in the intensive care unit is a modifiable prognostic factor that has a great effect on patient outcome and health care resources. Inappropriate treatment is usually associated with microorganisms resistant to the common antibiotics, which must be empirically targeted when risk factors are present. Previous antibiotic exposure, prolonged length of hospital stay, admission category, local susceptibilities, colonization pressure, and the presence of invasive devices increase the likelihood of infection by resistant pathogens. Consideration of issues beyond in vitro susceptibility, such as antibiotic physicochemistry, tissue penetration, and pharmacokinetic/pharmacodynamic-driven dosing, is mandatory for the optimization of antibiotic use.

Melatonin inhibits microglial activation, reduces pro-inflammatory cytokine levels, and rescues hippocampal neurons of adult rats with acute Klebsiella pneumoniae meningitis

Acute bacterial meningitis caused by Klebsiella pneumoniae (K. pneumoniae) is a major health threat with a high mortality rate and severe neuro-cognitive sequelae. The intense pro-inflammatory cytokine released from calcium-mediated microglial activation plays an important role in eliciting neuronal damage in the hippocampal region. Considering melatonin possesses anti-inflammatory and immuno-modulatory properties, the present study determined whether melatonin can effectively decrease inflammatory responses and prevent hippocampal damage in animals subjected to K. pneumoniae. Adult rats inoculated with K. pneumoniae received a melatonin injection immediately thereafter at doses of 5, 25, 50, or 100 mg/kg. Following 24 h of survival, all experimental animals were processed for time-of-flight secondary ion mass spectrometry (for detecting glial calcium intensity), isolectin-B4 histochemistry (reliable marker for microglial activation), pro-inflammatory cytokine measurement as well as cytochrome oxidase and in situ dUTP end-labeling (representing neuronal bio-energetic status and apoptotic changes, respectively). Results indicate that in K. pneumoniae-infected rats, numerous calcium-enriched microglia, enhanced pro-inflammatory cytokine, and various apoptotic neurons with low bio-energetic activity were detected in hippocampus. Following melatonin administration, however, all parameters including glial calcium intensity, microglial activation, pro-inflammatory cytokine levels, and number of apoptotic neurons were successfully decreased with maximal change observed at a melatonin dose of 100 mg/kg. Enzymatic data corresponded well with above findings in which all surviving neurons displayed high bio-energetic activity. As effectively reducing glia-mediated inflammatory response is neuro-protective to hippocampal neurons, the present study supports the clinical use of melatonin as a potential therapeutic agent to counteract K. pneumoniae meningitis-induced neuro-cognitive damage.

[Presumptive bacterial meningitis in adults: initial antimicrobial therapy]

CSF sterilization should be obtained very rapidly to reduce both mortality and morbidity due to bacterial meningitis. Thus, antibiotic treatment should be adapted to the suspected bacterium and administered as early as possible at high dosage with - if necessary - a loading dose and continuous perfusion. The rates of abnormal susceptibility to penicillin of Streptococcus pneumoniae, Neisseria meningitis and Haemophilus influenzae are 37%, 30% and 12% respectively. Thus, ceftriaxone or cefotaxim must be used as empirical treatment. Listeria monocytogenes remains fully susceptible to aminopenicillin, so, the combination aminopenicillin and aminoglycoside is the first-line treatment. Antibiotic resistance, allergy or contra-indications, are in fact rare but in these cases, antibiotic combinations are often needed. The latter are more or less complex and clinically validated; they include molecules such as vancomycine, fosfomycin, fluoroquinolone or linezolid.

Virulent clones of Klebsiella pneumoniae: identification and evolutionary scenario based on genomic and phenotypic characterization

Klebsiella pneumoniae is found in the environment and as a harmless commensal, but is also a frequent nosocomial pathogen (causing urinary, respiratory and blood infections) and the agent of specific human infections including Friedländer's pneumonia, rhinoscleroma and the emerging disease pyogenic liver abscess (PLA). The identification and precise definition of virulent clones, i.e. groups of strains with a single ancestor that are associated with particular infections, is critical to understand the evolution of pathogenicity from commensalism and for a better control of infections. We analyzed 235 K. pneumoniae isolates of diverse environmental and clinical origins by multilocus sequence typing, virulence gene content, biochemical and capsular profiling and virulence to mice. Phylogenetic analysis of housekeeping genes clearly defined clones that differ sharply by their clinical source and biological features. First, two clones comprising isolates of capsular type K1, clone CC23^K1 and clone CC82^K1, were strongly associated with PLA and respiratory infection, respectively. Second, only one of the two major disclosed K2 clones was highly virulent to mice. Third, strains associated with the human infections ozena and rhinoscleroma each corresponded to one monomorphic clone. Therefore, K. pneumoniae subsp. ozaenae and K. pneumoniae subsp. rhinoscleromatis should be regarded as virulent clones derived from K. pneumoniae. The lack of strict association of virulent capsular types with clones was explained by horizontal transfer of the cps operon, responsible for the synthesis of the capsular polysaccharide. Finally, the reduction of metabolic versatility observed in clones Rhinoscleromatis, Ozaenae and CC82^K1 indicates an evolutionary process of specialization to a pathogenic lifestyle. In contrast, clone CC23^K1 remains metabolically versatile, suggesting recent acquisition of invasive potential. In conclusion, our results reveal the existence of important virulent clones associated with specific infections and provide an evolutionary framework for research into the links between clones, virulence and other genomic features in K. pneumoniae.

Changing epidemiology of adult bacterial meningitis in southern taiwan: a hospital-based study

BACKGROUND

Many factors may influence the epidemiologic trend of adult bacterial meningitis (ABM). The objective of this study was to analyze recent epidemiologic trends of ABM in order to provide a better therapeutic strategy.

MATERIALS AND METHODS

The clinical features, laboratory data, and therapeutic outcomes of 181 ABM cases collected in the last 6.5 years (July 1999-December 2005) were analyzed. The results were compared with those of our previous study (202 cases, January 1986-June 1999).

RESULTS

The 181 cases consisted of 130 men (age range: 18-82 years) and 51 women (age range: 18-78 years). Monomicrobial infection and mixed infection were found in 165 cases and 16 cases, respectively. A preceding postneurosurgical state was noted in 56.9% (103/181) of cases. Despite a decrease in incidence, Klebsiella pneumoniae (25.5%, 42/165) was still the most common pathogen. A marked increase of Acinetobacter meningitis (11.5%, 19/165) was noted, which replaced Pseudomonas meningitis as the second most common Gram-negative pathogen in ABM. A marked increase in staphylococcal infection, accounting for 23% (38/165) of all cases, was also noted, of which 76% (29/38) were methicillin-resistant strains. The therapeutic result showed a mortality rate of 30.3% (55/181). Significant prognostic factors included septic shock and age at infection.

CONCLUSIONS

This study revealed a change in the epidemiologic trend of ABM, with an increase in the number of patients with a postneurosurgical state and a rising incidence of Acinetobacter and staphylococcal infections. Clinicians should pay greater attention to these changes, which may affect their management of ABM.

Clinical features and predictive factors of intraventricular rupture in patients who have bacterial brain abscesses

BACKGROUND

Intraventricular rupture of brain abscesses (IVRBA) remains a catastrophic and fatal complication of bacterial brain abscess (BBA). However, no information has been reported about the risk factors that are predictive of intraventricular rupture.

METHODS

This study was undertaken to determine the potential risk factors that are predictive of intraventricular ruptures in patients with BBA but without intraventricular rupture when arriving at the hospital. A comparison is also made between patients who already have IVRBA at the time of admission (initial IVRBA) and those who have the episode during hospitalisation (subsequent IVRBA).

RESULTS

62 patients, including 45 who had initial IVRBA and 17 who had subsequent IVRBA, were examined. Stepwise logistic regression analysis showed that the adjusted risk of intraventricular rupture during hospitalisation for patients with multiloculated brain abscesses had an odds ratio (OR) of 4.2 (95% confidence interval (CI) 1.24 to 14.3; p = 0.02) compared with those without multiloculated brain abscesses (referent); a reduction of 1 mm in the distance between the ventricle and brain abscesses would increase the rupture rate by 10% (p = 0.006, OR 0.9, 95% CI 0.83 to 0.97).

CONCLUSION

This study shows that if the abscess is deep seated, multiloculated and close to the ventricle wall, a reduction of 1 mm in the distance between the ventricle and brain abscesses will increase the rupture rate by 10%. Despite aggressive medical and surgical management shown in this series, many patients continue to progress poorly.

Fatal Klebsiella pneumoniae meningitis and emphysematous brain abscess after endoscopic variceal ligation in a patient with liver cirrhosis and diabetes mellitus

Procedure-related bacterial infections may complicate esophageal variceal ligation in cirrhosis patients. Here, we report a 58-year-old man with underlying diabetes and liver cirrhosis who developed Klebsiella pneumoniae meningitis and brain abscess with gas formation in brain parenchyma and ventricles after this procedure. Despite administration of appropriate antimicrobial therapy, he became comatose on the 3rd day of acute illness and died on the 4th day of hospitalization. This case highlights the indication for antimicrobial prophylaxis in cirrhotic patients with gastrointestinal bleeding, and the need for early and heightened awareness of central nervous system infections in cirrhotic patients with hepatic encephalopathy.

La méningite post-traumatique : incidence, microbiologie et pronostic

BACKGROUND AND PURPOSE

The aim of our study was to search for the incidence, the responsible organisms and the favoring causes of death of post-traumatic meningitis (PTM).

METHODS

This retrospective study was conducted over a seven-year period (January 1st, 1996 - December 31, 2002) in the ICU and the neurosurgery department of the Habib-Bourguiba University Hospital, Sfax, Tunisia.

RESULTS

Over the study period, 38 patients presented PTM (0.96% of patients hospitalized for head injury), 92% of them had received antibiotic prophylaxis on admission. Mean time between head injury and the diagnosis of PTM was 9+/- 8 days (range: 2-34 days). The most common isolated organisms were multidrug resistant A. baumanii, and K. pneumoniae and reduced susceptibility S. pneumoniae. Factors predictive of prognosis in the 14 days following the diagnosis of meningitis were Glasgow coma score (GCS) on the day of diagnosis of PTM, absence of nuchal rigidity, CSF protein, CSF/blood glucose ratio, and S. pneumoniae as the causal agent of PTM.

CONCLUSIONS

Antibioprophylaxis in patients with head trauma must be avoided to prevent the emergence of multidrug resistant bacteria when PTM occurs. GCS on the day of diagnosis of PTM, CSF protein concentration, CSF/blood glucose ratio, and S. pneumoniae as the causal agent of PTM are predictive factors of mortality of patients with PTM.

Klebsiella meningitis mimicking clinical deterioration from hemorrhage of a complex posterior fossa arteriovenous malformation

We report a case of a 33-year-old male with a history of complex posterior fossa arteriovenous malformation (AVM) with partial resection done in China; at follow-up in our unit, he presented with a 1-day history of acute deterioration of consciousness level after minor head injury. The clinical and radiologic features were compatible with spontaneous hemorrhage from the AVM, and the patient died 1 day after admission. However, postmortem examination revealed the direct cause of death was due to Klebsiella meningitis. The clinical catch is highlighted, and the importance of early and prompt detection of this condition is emphasized.

Adult Streptococcus pneumoniae meningitis in Southern Taiwan: epidemiologic trends and prognostic factors

The clinical features of 22 adult patients with Streptococcus pneumoniae meningitis, retrospectively collected over a 16-year period, were reviewed. Otopharyngeal infection, haematogenous spread and cranial neurosurgery continue to be the predominant routes of infection. Most patients acquired the infection in the community, and predisposing underlying conditions are common. The proportion of S. pneumoniae meningitis compared to all microorganisms causing meningitis in adults declined dramatically from 17% in the first 8 study years to 4% in the last 8 study years. However, all penicillin-resistant S. pneumoniae strains were found in the second half of the study period, accounting for 25% of these episodes. The overall mortality rates for the first and second halves of the study period were 43% and 63%, respectively. Third-generation cephalosporins were the antibiotics of choice for the treatment of S. pneumoniae meningitis in this study, however, the emergence of resistant strains may create a therapeutic challenge in the future. To avoid treatment failure, early diagnosis, careful monitoring of the clinical course and the choice of appropriate antibiotics according to the in vitro antimicrobial susceptibilities, are necessary.

The significance of seizures and other predictive factors during the acute illness for the long-term outcome after bacterial meningitis

BACKGROUND

Seizures are important neurological complications of bacterial meningitis, but no information about its epidemiology and the outcomes of seizures after community-acquired bacterial meningitis (CABM) in an adult population have been reported.

AIMS

To determine the frequency, clinical relevance, subtypes of seizures during the acute phase of bacterial meningitis, and the long-term outcomes of seizure complicating adult CABM.

METHODS

In this 12-year retrospective study, 117 adult patients were identified with culture-proven CABM. A comparison was made between the clinical data of the patients with and without seizures during hospitalization.

RESULTS

Thirty-one patients had seizures during CABM, accounting for 27% (31/117) of the episodes. The time interval between the onset of bacterial meningitis and the seizures was 1-21 days (mean, 4 days). Furthermore, 80% (25/31) of the episodes occurred within 24 h of presentation. Ten patients who had seizures progressed to status epilepticus. At follow-up after completing treatment, 10 patients completely recovered and were seizure-free, 19 died of meningitis during the acute stage and the other two progressed to chronic epilepsy.

CONCLUSION

A log-rank test demonstrated that the long-term outcome of adult CABM with acute seizures produced worse outcomes than for those who had no seizures, though no difference was noted between focal and generalized seizures. None of our patients without seizures in the acute phase of bacterial meningitis developed late seizures during the follow-up periods. Poor outcome in this study may attribute to neurological complications such as seizure, hydrocephalus, infection itself, or a combination of complications.

Bacterial meningitis in Hong Kong: 10-years’ experience

OBJECTIVE

We studied the etiology, clinical features and outcome of patients with bacterial meningitis from an urban Chinese city over a 10-years period.

METHODS

We reviewed the files of all persons aged 15-years old or above diagnosed with community-acquired bacterial meningitis from a regional hospital. The clinical findings, relevant laboratory and imaging results as well as outcome were recorded in cases with microbiological evidence of meningitis. Neurosurgical and pediatric patients were excluded.

RESULTS

Sixty-five patients between the ages of 15 and 86 years of age (mean 52 years) were identified of whom 18 (28%) died. The four most common causes were Mycobacteria tuberculosis (46%), Streptococcus pneumoniae (11%), Streptococcus suis (9%) and Klebsiella pneumoniae (8%). Neisseria meningitidis and Haemophilus influenzae were rare pathogens. The annual incidence of community-acquired bacterial meningitis was 1.27/100,000 adults. Delay in treatment was associated with a poorer prognosis (p<0.001, OR=38.84, CI=7.33-205.80).

CONCLUSION

The causative organisms found in this region of China differ from that reported from Europe and the US; tuberculous meningitis is the most common cause of bacterial meningitis.

Adjunctive dexamethasone treatment in acute bacterial meningitis

The initiation of antibiotic treatment on suspicion of bacterial meningitis is important, but it is not enough to improve the prognosis for patients, especially those with pneumococcal meningitis. The mortality and morbidity of pneumococcal meningitis are still devastating, and results of a recent randomised trial have shown evidence in favour of dexamethasone treatment given before or with the first antibiotic dose. Adjuvant dexamethasone is unequivocally recommended in children and adults with haemophilus meningitis or pneumococcal meningitis. The benefit of adjunctive dexamethasone is likely to be greatest in patients who are otherwise healthy and present early with acute bacterial meningitis. Dexamethasone is not currently recommended for the treatment of gram-negative bacillary meningitis and neonatal meningitis. Dexamethasone, before or with the first dose of antibiotic, is likely to be one of the most significant practice changes that will benefit many adults and children with common types of acute bacterial meningitis and has been of proven value in the developed world.