Review Question - QID 221240

This patient with sickle cell disease who presents with high fever, confusion, irritability, and meningismus most likely has bacterial meningitis. In patients with sickle cell disease, the most common pathogen causing meningitis is Streptococcus pneumoniae.

Children with sickle cell disease are at increased risk of infection with encapsulated organisms such as Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae type b, and Salmonella species due to functional asplenia from recurrent splenic infarctions. Of all these encapsulated organisms, S. pneumoniae is the most common cause of meningitis and sepsis in children with sickle cell disease. The pneumococcal polysaccharide vaccine PPSV23 helps prevent infection with S. pneumoniae in children with sickle cell disease and is administered in 2 doses, at 2 years of age and 3-5 years of age, respectively. Treatment of patients with suspected S. pneumoniae meningitis in healthy adults consists of empiric therapy with ceftriaxone, vancomycin, and dexamethasone until cerebrospinal fluid cultures return.

Pelkonen et al. reviewed the data regarding pediatric bacterial meningitis infections in Angola. They discuss how patients with sickle cell disease had a higher mortality rate and longer hospital stays than pediatric bacterial meningitis patients without sickle cell disease. They recommend increased public health efforts for early diagnosis of sickle cell disease.

Figure/Illustration A is a peripheral blood smear demonstrating sickled red blood cells (red circles). These cells are pathognomonic for sickle cell disease.

Incorrect Answers:
Answer 1: Neisseria meningitidis is also an encapsulated organism with a high propensity for infection in patients with sickle cell disease; however, it is not the most common cause of meningitis in patients with sickle cell disease. This patient lacks other common findings of this infection, such as myalgias or a petechial rash.

Answer 2: Non-typeable Haemophilus influenzae is an unencapsulated strain of Haemophilus which causes otitis media, conjunctivitis, and bronchitis. It is often confused with H. influenzae type b, which is an encapsulated organism that can cause meningitis and sepsis in patients with sickle cell disease.

Answer 3: Salmonella paratyphi is a common cause of osteomyelitis in patients with sickle cell disease, which would present with fever, malaise, and localized bone tenderness and swelling.

Answer 4: Staphylococcus aureus is an unencapsulated organism that can cause meningitis; however, it is not the most common cause of meningitis in patients with sickle cell disease.

Bullet Summary:
The most common cause of meningitis in patients with sickle cell disease is Streptococcus pneumoniae.