Differential Diagnosis

The patient presents with fevers, malaise, and chills, which are non-specific symptoms that can be associated with a wide range of conditions. Given her history and physical examination findings, the following differential diagnoses can be considered:

• Single Most Likely Diagnosis

  • Infective Endocarditis: The presence of a soft diastolic murmur at the lower left sternal border, fever, and recent dental procedure (a potential source of bacteremia) make infective endocarditis a strong consideration. The patient's diabetes mellitus may also contribute to an increased risk of infection.

• Other Likely Diagnoses

  • Bacteremia or Sepsis: Given the patient's symptoms of fever, malaise, and chills, along with tachycardia, bacteremia or sepsis from an unknown source should be considered. The recent dental procedure could be a potential source of infection.
  • Dental or Oral Infection: Although the patient reports no oral pain or swelling, a dental infection could still be present, especially given the recent dental procedure. However, the lack of specific oral symptoms makes this less likely.
  • Urinary Tract Infection (UTI): Despite the patient denying dysuria, a UTI could still be a cause of her symptoms, especially in a diabetic patient who may have altered sensation or presentation.

• Do Not Miss Diagnoses

  • Endocarditis (already mentioned but critical to emphasize due to its severity and the need for prompt diagnosis and treatment)
  • Sepsis: Early recognition and treatment of sepsis are crucial to prevent high morbidity and mortality.
  • Meningitis: Although the patient does not have specific symptoms like headache or stiff neck, meningitis can present subtly, especially in older adults or those with underlying conditions, and is a diagnosis that must not be missed due to its potential for severe consequences.

• Rare Diagnoses

  • Brucellosis: This zoonotic infection can cause fever, malaise, and other non-specific symptoms. It's less likely without a clear exposure history but should be considered in the appropriate context.
  • Osteomyelitis: Although the patient does not have localized pain or swelling, osteomyelitis could be a rare cause of her systemic symptoms, particularly if there was a recent infection or procedure that could have led to hematogenous spread of infection.
  • Neutropenic Fever: If the patient had been on any medications that could cause neutropenia (not mentioned, as metformin is not typically associated with this side effect), this could be a consideration, especially with fever and malaise. However, without additional risk factors, this is less likely.