Differential Diagnosis for a 7-year-old girl with sickle cell disease
Single most likely diagnosis
- Streptococcus pneumoniae: This is the most likely cause due to the patient's symptoms of fever, sleepiness, and decreased appetite, combined with a history of sickle cell disease. Patients with sickle cell disease are at increased risk of infections with encapsulated organisms like Streptococcus pneumoniae due to splenic dysfunction.
Other Likely diagnoses
- Escherichia coli: Although less common than Streptococcus pneumoniae in this context, E. coli can cause severe infections, including sepsis, especially in patients with compromised immune systems or those with urinary tract infections.
- Salmonella enteritidis: Salmonella infections are more common in patients with sickle cell disease and can present with a variety of symptoms, including fever and gastrointestinal symptoms, although the latter are not prominently featured in this case.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Staphylococcus aureus: While less likely than Streptococcus pneumoniae, Staphylococcus aureus can cause severe sepsis and has a high mortality rate if not promptly treated. The presence of petechiae could suggest a bacterial infection, although it's more commonly associated with meningococcal infections.
- Meningococcal infection: Although not listed among the choices, meningococcal infection (e.g., Neisseria meningitidis) is a critical "do not miss" diagnosis due to its rapid progression and high mortality rate. The presence of petechiae and fever should always prompt consideration of this diagnosis, despite the absence of nuchal rigidity.
Rare diagnoses
- Pseudomonas aeruginosa: This bacterium can cause infections in immunocompromised patients but is less commonly associated with the presentation described, especially without clear signs of respiratory or urinary tract infection.