Gram-negative bacillary meningitis

Spontaneous gram-negative bacillary meningitis in adult patients: characteristics and outcome

BACKGROUND

Spontaneous meningitis caused by gram-negative bacilli in adult patients is uncommon and poorly characterized. Our objective is to describe and compare the characteristics and the outcome of adult patients with spontaneous gram-negative bacilli meningitis (GNBM) and spontaneous meningitis due to other pathogens.

METHODS

Prospective single hospital-based observational cohort study conducted between 1982 and 2006 in a university tertiary hospital in Barcelona (Spain). The Main Outcome Measure: In-hospital mortality.

RESULTS

Gram-negative bacilli meningitis was diagnosed in 40 (7%) of 544 episodes of spontaneous acute bacterial meningitis. The most common pathogens were Escherichia coli and Pseudomonas species. On admission, characteristics associated with spontaneous gram-negative bacilli meningitis by multivariate modeling were advanced age, history of cancer, nosocomial acquisition of infection, urinary tract infection as distant focus of infection, absence of rash, hypotension, and a high cerebrospinal fluid white-cell count. Nine (23%) episodes were acquired in the hospital and they were most commonly caused by Pseudomonas. The in-hospital mortality rate was 53%. The mortality rate was higher among patients with Gram-negative bacillary meningitis than among those with other bacterial meningitis and their risk of death was twenty times higher than among patients infected with Neisseria meningitidis (odds ratio 20.47; 95% confidence interval 4.03-103.93; p<0.001).

CONCLUSIONS

Gram-negative bacilli cause 9% of spontaneous bacterial meningitis of known etiology in adults. Characteristics associated with GNBM include advanced age, history of cancer, nosocomial acquisition, and urinary tract infection as distant focus of infection. The mortality rate is higher among patients with gram-negative bacillary meningitis than among those with other bacterial meningitides.

Gram-negative Bacillary Meningitis after Cranial Surgery or Trauma in Adults

In order to assess the clinical features, aetiology, treatment and outcome of post-neurosurgical and post-traumatic Gram-negative bacillary meningitis (GNBM) we performed a retrospective review of all adult patients admitted to the Department of Neurosurgery who had Gram-negative bacilli cultured from cerebrospinal fluid (CSF) following a neurosurgical procedure or traumatic head/spinal injury. During the 12 y of the review 33 patients had CSF isolates of Gram-negative bacilli that were thought to be significant. The median patient age was 47 y (range 22-77 y) and 21 (64%) were male. Klebsiella pneumoniae, Enterobacter cloacae and Escherichia coli were the most common isolates. Minimal inhibitory concentrations (MIC) measured for half the patients' isolates resulted in 5 regimen changes, including 2 patients with E. cloacae meningitis in whom cephalosporin susceptibility decreased during cephalosporin treatment. Our recommended initial treatment was intravenous ceftriaxone and amikacin, subsequently tailored by susceptibility results; approximately half the patients remained on the antibiotics they started and half were changed to an alternate regimen, most often a carbapenem. Five patients (15%) died, 1 dying after cure of his GNBM. There were no failures in those who received more than 12 d of appropriate treatment: treatment for at least 14 d after the last positive CSF culture guaranteed cure. Initial ceftriaxone and amikacin subsequently changing to susceptibility driven alternatives, often a carbapenem, resulted in cure of 85% of our patients with GNBM.

Adults with spontaneous aerobic Gram-negative bacillary meningitis admitted to the intensive care unit

The characteristics of spontaneous aerobic Gram-negative bacillary meningitis (AGNBM) were determined in 40 adults requiring admission to an intensive care unit (ICU) during a 16-year period in ten French ICUs. Eight infections were hospital-acquired and most patients had predisposing factors, mainly chronic alcoholism and an immunocompromised status. Three immunosuppressed patients had disseminated strongyloidiasis. Gram's stain, cerebrospinal fluid and blood cultures were positive for 85%, 98% and 80% of cases, respectively. Escherichia coli (57%) and Klebsiella pneumoniae (17%) were the most frequent pathogens. In-ICU mortality was 38%. Spontaneous AGNBM is a rare complication of bacteraemia in adults. The severity of predisposing underlying diseases might explain the poor prognosis despite appropriate antimicrobial therapy.

Spontaneous Escherichia coli meningitis in an adult

Spontaneous meningitis due to gram-negative bacilli (excluding Hemophilus influenzae) is an infrequent infection in adult patients. It usually occurs in patients with underlying immunosuppressive conditions. Most of the cases are due to Escherichia coli and represent a complication of bacteraemia. The infection has a high mortality rate which may be as high as 90%, especially if associated with septicaemia. We report the case of a 53-y-old man with spontaneous, community-acquired Escherichia coli meningitis who was admitted with an unusual presentation. Blood and urine cultures were negative.

Enterobacteriaceae meningitis in adults: a review of 20 consecutive cases 1977-97

Enterobacteriaceae are not a frequent cause of meningitis in adults and are seen mainly in neurosurgical patients and on occasion in elderly and debilitated patients. Consequently, most series studied have been small and selected. In order to obtain a clearer clinical picture, we reviewed 20 consecutive cases of Enterobacteriaceae meningitis admitted to the Department of Infectious Diseases, Rigshospitalet, Copenhagen, during the years 1977-97. They comprised 1.5% of all cases of acute bacterial meningitis admitted to the department. All of the patients were either elderly and/or had 1 or more underlying diseases and predisposing factors. The clinical presentation and cerebrospinal fluid findings were not different from that of acute bacterial meningitis in general. The mortality rate was 40% and correlated with simultaneous bacteraemia. Complications were seen in a further 30% of patients and 25% survived with different sequelae. These high rates may, at least in part, be due to the advanced age and debilitated state of the patients studied. Escherichia coli was the most frequent of the Enterobacteriaceae.

Penetration of ciprofloxacin into human cerebrospinal fluid in patients with inflamed and non-inflamed meninges

The penetration of ciprofloxacin into the cerebrospinal fluid (CSF) in 25 patients with non-inflamed meninges and in 9 patients with inflamed meninges was studied. In the patients with non-inflamed meninges plasma and CSF were obtained 1-10 h after the second dose of ciprofloxacin and in the patients with inflamed meninges 1, 2, 3, 5, 7 and 9 h after the second dose. In the first group (non-inflamed meninges) data from 6 patients were obtained 4, 5 and 6 h post-dose. Mean ciprofloxacin concentrations in the CSF ranged from 0.073 mg/l to 0.106 mg/l during this observation time, while in the second group (inflamed meninges) they ranged from 0.089 to 0.260 mg/l. These results demonstrate that ciprofloxacin diffuses into the CSF at concentrations which exceed the MICs of Neisseria meningitidis and most gram-negative aerobic bacilli.

A comparison of central nervous lesions directly induced by Escherichia coli lipopolysaccharide in piglets, calves, rabbits and mice

To evaluate the role of endotoxin during Gram-negative bacterial meningitis, the nervous lesions of piglets, calves, rabbits and mice were compared by direct inoculation of Escherichia coli lipopolysaccharide into the central nervous system. Suppurative leptomeningitis was induced in piglets by small doses of lipopolysaccharide. Mice also had a mild suppurative inflammation in the leptomeninges. In contrast, calves showed suppurative pachymeningitis, but no lesions in the leptomeninges. Leptomeningeal inflammation was not induced in rabbits. Induction of the leptomeningitis by endotoxin was compared with sensitivity to intravenous or intraperitoneal endotoxin in these species.

CSF pharmacokinetics of ceftazidime in neurosurgical patients with an external ventriculostomy

In 11 neurosurgical patients (seven women, four men, aged 22-73 years) undergoing external ventriculostomy, serum and cerebrospinal fluid (CSF) pharmacokinetics of ceftazidime (CAZ) administered as a chemoprophylactic agent were evaluated. Concentrations of CAZ in CSF correlated significantly (p less than 0.05) with serum concentrations and with leucocyte counts in CSF. Peak concentrations in CSF (range 0-25.5 mg/l) exceeded the MIC90 of Staphylococcus species in two and of Pseudomonas and Enterobacter species in five of 11 patients. The MIC90 values of the other relevant bacteria causing CNS infections in these patients were surpassed in nine of 11 patients.

The many causes of meningitis

Meningitis should be suspected in a patient who presents with fever, meningism, or severe headache. A careful physical examination should be performed of perimeningeal foci, with emphasis on the sinuses, ears, throat, neck, and lungs. A history of exposure to tuberculosis, viral disease, rodents, or suspicious dairy products or farm animals may give clues to the source of the meningitis. Immunosuppression through the use of corticosteroids or chemotherapy for such conditions as Hodgkin's disease, lymphoma, leukemia, malnutrition, or acquired immunodeficiency syndrome (AIDS) should also be noted and alert the clinician to the possible presence of an unusual pathogen. Meningitis associated with leukemia or most of the non-T-cell lymphomas is likely to be from a common bacterial agent (often Listeria), unless the patient is being treated with a steroid or is receiving other chemotherapy. Patients with Hodgkin's disease or AIDS or who have been treated with a steroid are more likely to have cryptococcal or tuberculous meningitis. Neonates and the very elderly may present with only irritability or lethargy and fever, without any of the other common symptoms. In neonates up to one week of age, group B streptococcal infection should be suspected. Gram-negative organisms should be suspected in elderly patients and those who have had neurosurgery. In patients with CSF shunts, infection with coagulase-negative Staphylococcus should be assumed and these patients are treated empirically until results of cultures are received. Several noninfectious conditions may mimic infectious meningitis, as may some unusual causes of infectious meningitis (eg, syphilis and schistosomiasis), which have not been discussed in this article.

Acute neurologic infections

This article discusses acute bacterial, viral, toxin-mediated, and parasitic neurologic infections, emphasizing those infections that are potentially treatable, are rapidly fatal if untreated, or pose a significant risk of person-to-person transmission.