A 16-year-old adolescent male resident at the local police department’s boot camp was in his normal state of health until this morning, when he developed a headache and a fever of 105.8°F (41°C). Over the next 2 hours, he developed a stiff neck and began vomiting. He was brought to the emergency department (ED) when he developed altered mental status. No one else in the facility is ill. In the ED, his heart rate is 135 bpm, blood pressure 120/70 mm Hg, respiratory rate 25 breaths/min, and temperature 104°F (40°C). He is combative, unaware of his surroundings, and does not follow instructions. Kernig and Brudzinski signs are present.
What is the most likely diagnosis?
How would you confirm the diagnosis?
What treatment is indicated?
What are possible complications?
ANSWERS TO CASE 34: Bacterial Meningitis
Summary: A 16-year-old adolescent boy has fever, headache, stiff neck, and altered mental status. He is tachycardic but normotensive.
• Most likely diagnosis: Bacterial meningitis
• Confirm diagnosis: Lumbar puncture (LP)
• Treatment: Intravenous antibiotics
• Complications: Deafness, cranial nerve palsies, and, rarely, hemiparesis or global brain injury.
1. Describe the typical presentation of bacterial meningitis.
2. Describe how a patient’s age affects the presentation and outcome of bacterial meningitis.
3. List typical pathogens and appropriate treatment strategies by age group.
This teen has the typical triad of meningitis symptoms: fever, headache, and a stiff neck; his altered mental status is another often-seen finding. Other causes of mental status changes include viral meningoencephalitis, trauma, intentional or accidental ingestion, and hypoglycemia. Of these alternatives, only viral meningoencephalitis would likely explain the fever and stiff neck.
BRUDZINSKI SIGN: A physical finding consistent with meningitis; while the patient is supine, the neck is passively flexed resulting in involuntary knee and hip flexion.
ENCEPHALITIS: Brain parenchyma inflammation causing brain dysfunction.
KERNIG SIGN: A physical finding consistent with meningitis; while the patient is supine, the legs are flexed at the hip and knee at 90° angle resulting in pain with leg extension.
MENINGITIS: Leptomeningeal inflammations, typically infectious, but may also be caused by foreign substances.
The microbiology and clinical presentation of meningitis vary based on the patient’s age. The incidence of neonatal meningitis is between 0.2 and 0.5 cases per 1000 live births, most commonly due to Escherichia coli and group B Streptococcus (Streptococcus agalactiae). Listeria monocytogenesand other organisms (Citrobacter sp, Staphylococcus sp, group D streptococci, and Candida sp) are less common. Infants at increased risk for meningitis include low-birth-weight and preterm infants, and those born to mothers with chorioamnionitis, after a prolonged rupture of the amniotic membranes, or by traumatic delivery. Most neonatal bacterial meningitis occurs by hematogenous spread. Clinical symptoms in infants are nonspecific and not the typical triad of headache, fever, and stiff neck; instead, infants may have thermal instability (often hypothermia), poor feeding, emesis, seizures, irritability, and apnea. Infants may have a bulging fontanelle, and they demonstrate generalized hyper- or hypotonicity.
Bacterial meningitis in older children is usually caused by Streptococcus pneumoniae or Neisseria meningitidis; vaccination has essentially eliminated Haemophilus influenzae type B. Other rarer causes in this age group include Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Salmonella sp, and Listeria monocytogenes.
The incidence of pneumococcal meningitis is 1 to 6 cases per 100,000 children per year, more commonly occurring in the winter. It is an encapsulated pathogen; children with a poorly functioning or absent spleen are at higher risk. Children with sickle cell diseasehave an infection incidence 300 times greater than in unaffected children. Other risk factors include sinusitis, otitis media, pneumonia, and head trauma with subsequent cerebrospinal fluid (CSF) leak.
Neisseria meningitidis colonizes the upper respiratory tract in approximately 15% of normal individuals; carriage rates up to 30% are seen during invasive disease outbreaks. Disease appears to be caused by “new” infection rather than long-term carriage. In the United States, most disease is caused by serotypes B and C. Family members and day care workers in close contact with children having meningitis are at 100- to 1000-fold increased risk for contracting disease. A plethora of other bacterial, viral, fungal, and mycobacterial agents can cause meningitis.
The classic symptoms of meningitis seen in older children and adultsmay be accompanied by mental status changes, nausea, vomiting, lethargy, restlessness, ataxia, back pain, Kernig and Brudzinski signs, and cranial nerve palsies. Approximately one-quarter to one-third of patients have a seizure during the illness course. Patients with N meningitidis can have a petechial or purpuric rash (purpura fulminans), which is associated with septicemia. Patients with septicemia due to N meningitidis often are gravely ill and may or may not have associated meningitis.
The test of choice for suspected meningitis is an LP, which usually can be performed safely in children with few complications. Contraindicationsinclude a skin infection over the planned puncture site,evidence of or clinical concern for increased intracranial pressure, and a critically ill patient who may not tolerate the procedure. Cerebrospinal fluid analysis includes Gram stain and culture, white and red blood cell counts, and protein and glucose analysis. Bacterial antigen screens can be performed in patients already receiving antibiotics before the LP; these antigens may persist for several days, even when the culture is negative. Typical bacterial meningitis findings include an elevated opening pressure, several hundred to thousands of white blood cells with polymorphonuclear cell predominance, and elevated protein and decreased glucose levels.
Treatment strategies vary by patient age, likely pathogens, and local resistance patterns. A CSF Gram stain can guide the decision-making process. In the neonatal period, ampicillin often is combined with a third-generation cephalosporin or an aminoglycoside to cover infections caused by group B Streptococcus, L monocytogenes, and E coli. Neonates in an intensive care unit may be exposed to nosocomial infections; prevalent pathogens in that nursery must be considered.
In some locales, more than half of the pneumococcal isolates are intermediately or highly penicillin resistant; 5% to 10% of the organisms are cephalosporin resistant. Thus, in suspected pneumococcal meningitis, a third-generation cephalosporin combined with vancomycin is often recommended. Most N meningitidis strains are susceptible to penicillin or cephalosporins.
Acute meningitis complicationsmay include seizures, cranial nerve palsies, cerebral infarction, cerebral or cerebellar herniation, venous sinus thrombosis, subdural effusions, syndrome of inappropriate (secretion) of antidiuretic hormone (SIADH) with hyponatremia, and central diabetes insipidus. The most common long-term sequela is hearing loss (up to 30% of patients with pneumococcus); patients with bacterial meningitis usually have a hearing evaluation at the conclusion of antibiotic treatment. Mental retardation, neuropsychiatric and learning problems, epilepsy, behavioral problems, vision loss, and hydrocephalus are less commonly seen.
34.1 A 13-year-old boy has a 1-day history of fever and lethargy, and was unable to be awoken this morning. In the emergency department his respiratory rate is 7 breaths/min, heart rate 55 bpm, temperature 105.8°F (41°C), and blood pressure (BP) 60/40 mm Hg. He has altered mental status, a stiff neck, and a purpuric rash over his trunk. Which of the following is the most appropriate next step in the management of this patient?
A. Computed tomography of the head
B. Intravenous antibiotics
D. Lumbar puncture
E. Serum chemistries
34.2 An 8-year-old girl has persistent fever and headaches. Her parents report that for the 2 weeks prior she has complained of frontal headache that was significant enough to keep her away from school. She has had intermittent temperature elevations to 101°F (38.3°C), and she started vomiting a nonbloody, nonbilious fluid a few days ago. She has had frequent otitis media and sinusitis episodes, but her last episode of otitis media occurred approximately 5 weeks ago. On examination, you find a lethargic girl in no respiratory distress. She has a temperature of 100°F (37.7°C), heart rate 109 bpm, and blood pressure (BP) 100/60 mm Hg. She has nuchal rigidity and frontal sinus tenderness. Which of the following is the most appropriate next step in the management of this patient?
A. Computed tomography of the head
B. Intravenous promethazine for emesis
C. Lumbar puncture
D. Sinus radiographs
E. Trial of subcutaneous sumatriptan for migraine
34.3 A 2-week-old infant develops a temperature to 102°F (38.9°C). Pregnancy and delivery were uncomplicated. The irritable, fussy infant has a heart rate of 170 bpm and respiratory rate 40 breaths/min. The anterior fontanelle is full, but he has no nuchal rigidity; the rest of the examination is unremarkable. Which of the following is the most appropriate management of this infant?
A. Encourage oral fluids and office follow-up in 24 hours.
B. Order computed tomography of the head followed by an LP.
C. Perform an LP, blood culture, and urine culture, and admit to the hospital.
D. Prescribe intramuscular ceftriaxone and clinic follow-up in 1 week.
E. Prescribe oral amoxicillin and clinic follow-up in 1 week.
34.4 A 14-year-old boy complains of fever and stiff neck for 2 days. He has a sore throat and has been unable to eat for a day because of the pain. On examination, he is alert and oriented, but he has nuchal rigidity and posterior pharyngeal midline fullness. He drools to avoid the pain of swallowing. Which of the following is the best next step in the management of this patient?
A. Order computed tomography of the head.
B. Order lateral neck radiographs.
C. Perform a lumbar puncture.
D. Prescribe intramuscular antibiotics.
E. Prescribe oral antibiotics.
34.1 C. This patient in the question has meningococcemia; he is in shock, and he is about to die. The ABCs of Airway, Breathing, and Circulation should always take precedence over diagnostic studies. N meningitidiscan present as meningococcemia with purpura and shock; in some cases patients will also have meningitis. The LP should be deferred, however, until he is clinically stable. Intravenous fluids through a large-bore catheter to support his cardiovascular status and antibiotics should be administered immediately after stabilization of his airway.
34.2 A. This girl’s history of sinusitis and a prolonged headache with worsening emesis and nuchal rigidity suggest an intracranial abscess due to her sinusitis. In her case, CNS imaging (with contrast) is performed prior to an LP. Performing an LP when a mass lesion might be causing increased intracranial pressure can result in herniation of the brain and patient death. Sinus films would show sinusitis but would not reveal an intracranial abscess. Merely treating her symptoms with promethazine or sumatriptan would delay the diagnosis of her underlying problem.
34.3 C. This infant potentially has a serious bacterial infection, and an evaluation including an LP is performed. Infants do not reliably demonstrate a Kernig or Brudzinski sign; a lack of nuchal rigidity should not preclude an LP. Computed tomography scan before an LP in an infant with an open anterior fontanelle is rarely necessary, as brain herniation is exceedingly rare. A course of oral antibiotics, or a single dose of ceftriaxone, is not sufficient to treat meningitis or septicemia.
34.4 B. A retropharyngeal abscess is causing this boy’s neck stiffness; he does not have meningitis. He has a normal mental status, dysphagia, and fullness in his oropharynx. Lateral neck films are a simple way to confirm this diagnosis. Prescribing antibiotics without identifying the diagnosis would not be appropriate in this case.
The typical meningitis presentation in older children consists of fever, headache, and nuchal rigidity.
Nuchal rigidity is not a reliable finding of meningitis until 12 to 18 months of age.
Pneumococcal disease (including meningitis) is more common in patients with functional or anatomic asplenia.
Approximately one-third of meningitis patients have a seizure at some point in the disease.
Typical cerebrospinal fluid findings of bacterial meningitis include elevated protein level, reduced glucose concentration, and several hundred to thousands of white blood cells per cubic millimeter.
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