Recognizing, Managing, and Preventing Pneumococcal Meningitis: An Expert Interview With Russell W. Steele, MD

Russell W. Steele, MD

Disclosures

August 05, 2002

Introduction

The recent report by the FDA of a suspected link between cochlear implants and the development of bacterial meningitis, specifically pneumococcal meningitis, has heightened awareness of this disease. To explore the various aspects of pneumococcal meningitis, Medscape spoke with Russell W. Steele, MD, Professor and Vice-Chairman of the Department of Pediatrics, Louisiana State University Health Sciences Center, New Orleans, and Division Head, Clinical Department of Infectious Diseases, Children's Hospital, New Orleans, Louisiana.

Streptococcus pneumoniae

is the most frequent cause of meningitis in the United States, accounting for 47% of all cases, followed by

Neisseria meningitides

, the meningococcus (25%), group B streptococcus (12%),

Listeria monocytogenes

(8%), and

Haemophilus influenzae

(7%).

[1]

The pneumococcus continues to exhibit the highest mortality and morbidity rates among these more common bacterial causes of meningitis, with a 4% to 16% mortality rate in children and a substantially higher rate in adults.

[2]

Death is the result in more than half of the elderly adults (older than 70 years of age) infected with pneumococcal meningitis. Neurologic sequelae (eg, deafness, hydrocephalus, seizure disorders, and mental retardation) occur in one third to one half of survivors.



S pneumoniae is even more prevalent in cases of meningitis following cranial trauma, anatomic defects of the fronto-ethmoidal region, or surgical procedures of the head and face, accounting for 80% to 90% of isolates with these predisposing factors. A full understanding of the clinical presentation and management of pneumococcal meningitis is therefore essential for all physicians.

Medscape: How does the clinical presentation of pneumococcal meningitis differ from that of other causes of bacterial meningitis and central nervous system (CNS) infections?

Dr. Steele: The duration of symptoms prior to medical intervention is relatively brief, averaging just 1 1/2 to 2 1/2 days. Half of patients present with the classic triad of fever, mental status changes, and nuchal rigidity. All others have at least 1 of these signs. However, 1 in 14 have only fever, but two thirds of these patients develop neck stiffness early in their course. One in 6 will present in shock. Most deaths occur during the acute phase of infection, so appropriate and aggressive early management is critical to assure survival.

Medscape: What diagnostic studies need to be undertaken prior to initiation of antimicrobial therapy?

Dr. Steele: With the exception of examination of the cerebrospinal fluid (CSF), laboratory studies are rarely helpful. Patients tend to have significant leukocytosis, with an average white blood cell (WBC) count of 20,000/mm3, but this, of course, is a nonspecific finding. Moreover, a lower WBC count is a marker for poorer prognosis. The WBC count in the CSF is usually > 1000/mm3, but 1% to 2% of all cases will initially have a normal WBC count (ie, < 10 WBC/mm3). The CSF glucose is usually < 40% of a concomitant serum glucose, and the protein is elevated well above the reference range of 40-45 mg/dL. The CSF Gram stain is positive in 90% to 95% of cases, latex agglutination for pneumococcal antigen in 97%, and CSF culture in 95%. Culture-negative cases are largely attributable to pretreatment with parenteral (not oral) antibiotics. About 3% of cases will have positive blood cultures with a CSF pleocytosis but negative CSF cultures.

Medscape: What is the current recommendation for empiric antibiotic treatment?

Dr. Steele: S pneumoniae strains that are nonsusceptible to penicillin and third-generation cephalosporins (ie, ceftriaxone and cefotaxime) have been identified worldwide, with as many as 8% of pneumococci demonstrating this multiresistant pattern in some regions. Vancomycin resistance has not yet been observed. For that reason, initial combination therapy with vancomycin and either cefotaxime or ceftriaxone should be administered to all patients with suspected meningitis unless there is compelling evidence that the cause is not S pneumoniae, such as gram-negative diplococci in the CSF and a positive antigen detection assay for meningococcus. Vancomycin should not be given as initial monotherapy for cases where pneumococcal etiology is identified by Gram stain or antigen assay, because data for such routine therapy are limited.

Lumbar puncture should be repeated 24-48 hours into therapy if the patient has not clearly improved and the organism is resistant to cephalosporins. As soon as it is determined that the strain of pneumococcus causing disease is susceptible to ceftriaxone and cefotaxime, vancomycin can be discontinued.

Medscape: Is dexamethasone recommended as adjunctive therapy?

Dr. Steele: Most experts do not recommend dexamethasone, since controlled clinical trials have not clearly demonstrated benefit for reducing deafness and other neurologic sequelae. In addition, dexamethasone is an antipyretic, which can, by itself, produce clinical improvement, even when antimicrobial therapy is inadequate.[3] Such changes may jeopardize appropriate clinical assessment and result in inadequate management.

Medscape: Where should patients be managed?

Dr. Steele: It would be prudent to manage all cases of bacterial meningitis in an intensive care unit, at least during the early phase. Complications may require the expertise of critical care medicine specialists, neurologists, and infectious diseases experts, who are more likely to be available in referral-type hospitals that have these special acute care units.

Medscape: How can pneumococcal meningitis be prevented in patients undergoing surgical placement of cochlear implants?

Dr. Steele: Although no specific clinical trials have been undertaken to determine the value of interventions to prevent meningitis in patients who will receive cochlear implants, data from other studies designed to prevent pneumococcal infection offer useful guidance. The following recommendations are therefore offered for surgical candidates:

  • Administer pneumococcal polysaccharide vaccine (Pneumovax) 3-4 weeks prior to surgery.

  • Administer conjugate pneumococcal vaccine (Prevnar)[4] 2 weeks prior to surgery.

  • Culture the posterior nasopharynx for S pneumoniae and determine its susceptibility pattern 3-7 days prior to surgery.

  • Intravenously administer ceftriaxone (Rocephin) 2 g/day x 3 days beginning on the day of surgery (80 mg/kg/day for children, to a maximum of 2 g).

  • If the patient is colonized with cephalosporin-resistant pneumococci, substitute intravenous vancomycin 1 g every 12 hours for 3 days (40 mg/kg/day divided into equal doses every 6 hours for children).

  • Consider meningococcal vaccine, also given 2-4 weeks prior to surgery. However, the meningococcus is a rare cause of postoperative or posttrauma meningitis.

Medscape: How can pneumococcal meningitis be prevented in cochlear implant recipients?

Dr. Steele: Patients who have already received a cochlear implant should be given both pneumococcal vaccines -- polysaccharide and conjugate -- as soon as possible. The meningococcal vaccine can also be considered for implant recipients.

Will this change your clinical practice? Let me know at harry_goldhagen@webmd.net.

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