Bacterial Meningitis beyond the Newborn Period
Sabah Mohsin Al-Maamuri MD
FICPS
Meningitis is an inflammation of the meninges. mellitus, Cushing syndrome, and coma secondary to
Because death can occur in more than 5% of cases drug overdose. Genetic factors also may play a role.
and morbidity may occur in 30% of survivors, it is still
Other bacteria, such as group B streptococcus,
a feared childhood infection.
Listeria monocytogenes, Salmonella, and
Epidemiology: Fusobacterium necrophorum, can cause meningitis in
"normal" children. Skin flora should be suspected in
Common causes of bacterial meningitis in children
children with a dermoid sinus, meningomyelocele, or
older than 1 month of age are Neisseria
hydrocephalus and a cerebrospinal fluid (CSF) shunt.
meningitidis, Streptococcus pneumoniae and, until
Cystic fibrosis or burn patients may develop
recently, Hemophilus influenzae type b (Hib). While
Staphylococcus aureus or Pseudomonas aeruginosa
in those < 1 mo, group B streptococcus (GBS)
meningitis after colonization. In a humidified
followed by Listeria monocytogenes are the most
atmosphere, P. aeruginosa or Serratia marcescens
common. Most cases occur in children between 1
infection may occur. Children with sickle cell disease,
month and 5 years of age, with the highest risk being
and congenital asplenia are especially susceptible to
in infants aged 6 to 12 months.
Salmonella infection, in addition to H. influenzae and
The incidence of meningococcal meningitis in the S. pneumoniae. Children who have
developed countries in those aged 1 to 23 months is reticuloendothelial malignancies, are undergoing
4.5 per 100,000. It is a Gram-negative diplococcus. chemotherapy, or have indwelling catheters may
Meningococcal disease is more common in males. develop meningitis from organisms of low virulence,
The disease generally is acquired from carriers who such as Streptococcus mitis. In immunocompromised
can harbor the organism for months. The incidence of children, Bacteroides fragilis is a frequent anaerobic
disease peaks in winter. The incubation period is from cause of meningitis. Congenital or acquired anatomic
1 to 10 days. Host factors, such as terminal defects, such as a cribiform plate fracture, should be
complement deficiency, complement-depleting investigated in cases of recurrent meningitis.
diseases, or properdin deficiency, increase
Meningitis with two bacterial types in a CSF culture
susceptibility to disease.
may occur in 1% of cases. Meningitis with a bacteria
S. pneumoniae is a gram-positive diplococcus with and a virus or fungus occurs rarely. The clinical
tens serotypes. Sepsis and meningitis occur most course usually is that of bacterial meningitis.
frequently with specific serotypes (4, 6B, 9V, 14, 18C,
Pathogenesis:
19F, and 23F).
Initially, upper respiratory tract infection occurs.
Hib is a gram-negative coccobacillus. Historically, it
Bacteremia follows, with opsonization and
was the leading cause of bacterial meningitis in many
phagocytosis inhibited by bacterial capsules.
developed countries. In countries where Hib
Meningeal seeding occurs. Invasion from a
vaccination is not yet widespread, the disease
contiguous infection (e.g., mastoiditis) also can occur.
continues to be a common occurrence, with a peak
incidence occurring in late autumn or early winter. Organisms initially are found in the lateral and dorsal
Host factors are important because meningitis occurs longitudinal (sagittal) sinuses. Central nervous system
with increased frequency in children with diabetes (CNS) blood flows may be reduced by 25% to 50%.
Page 1 of 11
, Dural inflammation slows the flow from the transport across the inflamed choroid plexus.
subarachnoid space to the sinuses, thereby Increased glucose use results in the excess
permitting spread of infection. A meningeal exudate production of lactate production and the depletion of
occurs over the brain. The spinal cord may be the high-energy compounds adenosine triphosphate
encased in pus. Purulent material may develop in the and phosphocreatine.
ventricles and the ventricular wall and around the
Increased CSF protein is caused partly by the flow of
veins and venous sinuses.
albumin-rich fluid into the subdural space secondary
Cerebral cortex damage produces the neurologic to inflammation and increased vascular permeability.
sequelae of meningitis.
Clinical manifestations and complications:
Nerve inflammation leads to meningeal symptoms
Meningitis can develop slowly over the course of
and signs. Early pressure on peripheral nerves may
several days, or it can be fulminant, with onset
lead to motor or sensory deficits.
occurring within hours. The clinical presentation
Cerebral edema results from vasogenic, interstitial, depends on the age of presentation:
and cytotoxic processes. Vasogenic edema results
In infants: fever or hypothermia, lethargy, respiratory
from increased permeability of the blood brain barrier.
distress, jaundice, vomiting, diarrhea, poor feeding,
Interstitial edema occurs with decreased CSF
restlessness, irritability, decreased muscle tone, full
resorption as proteins, leukocytes, and debris
fontanelle, seizures.
interfere with the function of the arachnoid villi.
Cytotoxic edema results from host and bacterial toxic In children: fever, chills, photophobia, anorexia,
factors, which increase intracellular water and sodium confusion, altered consciousness, coma, cranial
and loss of intracellular potassium. nerve palsies, upper respiratory symptoms, petechial
or purpuric rash, myalgia, arthralgia, nuchal rigidity,
Increased ICP often exceeds 300 mm H2O.
headache, nausea, vomiting, malaise, restlessness,
Hypoxemia and ischemia from decreased perfusion
lethargy, ataxia, hyperesthesia, back pain, seizures,
may result. Papilledema is a rare occurrence because
kernig sign, brudzinski sign.
of the brief duration of increased pressure.
Hydrocephalus rarely occurs beyond the neonatal Fever and meningeal inflammation symptoms occur
period. Communicating hydrocephalus may result in 85% of patients. Nuchal rigidity may appear late,
from adhesive arachnoid thickening about the basal especially in a young child. Seizures occur in 30% of
cisterns. Obstructive hydrocephalus may result from cases at some time before or during the course of
fibrosis and reactive gliosis obliterating the aqueduct illness. Infants may have a bulging fontanelle, but
of Sylvius or the foramina of Magendie and Luschka. such appears late and in only approximately 30% of
In some cases, meningitis is associated with the infants (13% of children without meningitis).
syndrome of inappropriate antidiuretic hormone Papilledema is a rare development; if present, a
release (SIADH), causing water retention and a search for other processes (e.g., brain abscess,
relative sodium loss by the kidney. SIADH increases venous sinus occlusion, subdural empyema) should
the risk of developing electrolyte abnormalities, be performed.
increased ICP, and seizures. Dehydration also can
Transient or permanent cranial nerve damage may
occur from increased insensible losses and
cause deafness, vestibular disturbance, ataxia, and
decreased intake.
extraocular or facial nerve paralysis. Optic-nerve
Hypoglycorrhachia and acidosis result in part from arachnoiditis may lead to optic atrophy and blindness.
increased glucose use and decreased glucose Focal neurologic deficits may exist on admission in
Page 2 of 11
Sabah Mohsin Al-Maamuri MD
FICPS
Meningitis is an inflammation of the meninges. mellitus, Cushing syndrome, and coma secondary to
Because death can occur in more than 5% of cases drug overdose. Genetic factors also may play a role.
and morbidity may occur in 30% of survivors, it is still
Other bacteria, such as group B streptococcus,
a feared childhood infection.
Listeria monocytogenes, Salmonella, and
Epidemiology: Fusobacterium necrophorum, can cause meningitis in
"normal" children. Skin flora should be suspected in
Common causes of bacterial meningitis in children
children with a dermoid sinus, meningomyelocele, or
older than 1 month of age are Neisseria
hydrocephalus and a cerebrospinal fluid (CSF) shunt.
meningitidis, Streptococcus pneumoniae and, until
Cystic fibrosis or burn patients may develop
recently, Hemophilus influenzae type b (Hib). While
Staphylococcus aureus or Pseudomonas aeruginosa
in those < 1 mo, group B streptococcus (GBS)
meningitis after colonization. In a humidified
followed by Listeria monocytogenes are the most
atmosphere, P. aeruginosa or Serratia marcescens
common. Most cases occur in children between 1
infection may occur. Children with sickle cell disease,
month and 5 years of age, with the highest risk being
and congenital asplenia are especially susceptible to
in infants aged 6 to 12 months.
Salmonella infection, in addition to H. influenzae and
The incidence of meningococcal meningitis in the S. pneumoniae. Children who have
developed countries in those aged 1 to 23 months is reticuloendothelial malignancies, are undergoing
4.5 per 100,000. It is a Gram-negative diplococcus. chemotherapy, or have indwelling catheters may
Meningococcal disease is more common in males. develop meningitis from organisms of low virulence,
The disease generally is acquired from carriers who such as Streptococcus mitis. In immunocompromised
can harbor the organism for months. The incidence of children, Bacteroides fragilis is a frequent anaerobic
disease peaks in winter. The incubation period is from cause of meningitis. Congenital or acquired anatomic
1 to 10 days. Host factors, such as terminal defects, such as a cribiform plate fracture, should be
complement deficiency, complement-depleting investigated in cases of recurrent meningitis.
diseases, or properdin deficiency, increase
Meningitis with two bacterial types in a CSF culture
susceptibility to disease.
may occur in 1% of cases. Meningitis with a bacteria
S. pneumoniae is a gram-positive diplococcus with and a virus or fungus occurs rarely. The clinical
tens serotypes. Sepsis and meningitis occur most course usually is that of bacterial meningitis.
frequently with specific serotypes (4, 6B, 9V, 14, 18C,
Pathogenesis:
19F, and 23F).
Initially, upper respiratory tract infection occurs.
Hib is a gram-negative coccobacillus. Historically, it
Bacteremia follows, with opsonization and
was the leading cause of bacterial meningitis in many
phagocytosis inhibited by bacterial capsules.
developed countries. In countries where Hib
Meningeal seeding occurs. Invasion from a
vaccination is not yet widespread, the disease
contiguous infection (e.g., mastoiditis) also can occur.
continues to be a common occurrence, with a peak
incidence occurring in late autumn or early winter. Organisms initially are found in the lateral and dorsal
Host factors are important because meningitis occurs longitudinal (sagittal) sinuses. Central nervous system
with increased frequency in children with diabetes (CNS) blood flows may be reduced by 25% to 50%.
Page 1 of 11
, Dural inflammation slows the flow from the transport across the inflamed choroid plexus.
subarachnoid space to the sinuses, thereby Increased glucose use results in the excess
permitting spread of infection. A meningeal exudate production of lactate production and the depletion of
occurs over the brain. The spinal cord may be the high-energy compounds adenosine triphosphate
encased in pus. Purulent material may develop in the and phosphocreatine.
ventricles and the ventricular wall and around the
Increased CSF protein is caused partly by the flow of
veins and venous sinuses.
albumin-rich fluid into the subdural space secondary
Cerebral cortex damage produces the neurologic to inflammation and increased vascular permeability.
sequelae of meningitis.
Clinical manifestations and complications:
Nerve inflammation leads to meningeal symptoms
Meningitis can develop slowly over the course of
and signs. Early pressure on peripheral nerves may
several days, or it can be fulminant, with onset
lead to motor or sensory deficits.
occurring within hours. The clinical presentation
Cerebral edema results from vasogenic, interstitial, depends on the age of presentation:
and cytotoxic processes. Vasogenic edema results
In infants: fever or hypothermia, lethargy, respiratory
from increased permeability of the blood brain barrier.
distress, jaundice, vomiting, diarrhea, poor feeding,
Interstitial edema occurs with decreased CSF
restlessness, irritability, decreased muscle tone, full
resorption as proteins, leukocytes, and debris
fontanelle, seizures.
interfere with the function of the arachnoid villi.
Cytotoxic edema results from host and bacterial toxic In children: fever, chills, photophobia, anorexia,
factors, which increase intracellular water and sodium confusion, altered consciousness, coma, cranial
and loss of intracellular potassium. nerve palsies, upper respiratory symptoms, petechial
or purpuric rash, myalgia, arthralgia, nuchal rigidity,
Increased ICP often exceeds 300 mm H2O.
headache, nausea, vomiting, malaise, restlessness,
Hypoxemia and ischemia from decreased perfusion
lethargy, ataxia, hyperesthesia, back pain, seizures,
may result. Papilledema is a rare occurrence because
kernig sign, brudzinski sign.
of the brief duration of increased pressure.
Hydrocephalus rarely occurs beyond the neonatal Fever and meningeal inflammation symptoms occur
period. Communicating hydrocephalus may result in 85% of patients. Nuchal rigidity may appear late,
from adhesive arachnoid thickening about the basal especially in a young child. Seizures occur in 30% of
cisterns. Obstructive hydrocephalus may result from cases at some time before or during the course of
fibrosis and reactive gliosis obliterating the aqueduct illness. Infants may have a bulging fontanelle, but
of Sylvius or the foramina of Magendie and Luschka. such appears late and in only approximately 30% of
In some cases, meningitis is associated with the infants (13% of children without meningitis).
syndrome of inappropriate antidiuretic hormone Papilledema is a rare development; if present, a
release (SIADH), causing water retention and a search for other processes (e.g., brain abscess,
relative sodium loss by the kidney. SIADH increases venous sinus occlusion, subdural empyema) should
the risk of developing electrolyte abnormalities, be performed.
increased ICP, and seizures. Dehydration also can
Transient or permanent cranial nerve damage may
occur from increased insensible losses and
cause deafness, vestibular disturbance, ataxia, and
decreased intake.
extraocular or facial nerve paralysis. Optic-nerve
Hypoglycorrhachia and acidosis result in part from arachnoiditis may lead to optic atrophy and blindness.
increased glucose use and decreased glucose Focal neurologic deficits may exist on admission in
Page 2 of 11
