When a Urinary Tract Infection Does Not Explain Bacteremia. A Case Report of Sepsis, Klebsiella pneumoniae, and Missed Infective Endocarditis
- Faraz Afzal
- 3 days ago
- 3 min read
Introduction
Fever and bacteremia in older patients with an indwelling urinary catheter are frequently interpreted as urosepsis. In most cases this assumption is correct, but it may also lead to diagnostic anchoring. This case report illustrates how a rare but life-threatening cause of bacteremia was only uncovered after the clinical course failed to follow the expected trajectory.
Patient Presentation and Admission
A man in his seventies was admitted with fever, acute confusion, and mild respiratory distress. His had a known valvular heart disease with previously documented mild to moderate aortic regurgitation.
He had an indwelling urinary catheter following acute urinary retention due to benign prostatic hyperplasia and had experienced several urinary tract infections. One week prior to admission, he developed upper respiratory symptoms and was started on phenoxymethylpenicillin by his general practitioner.
On admission, he was febrile with a temperature of 38.7 °C, mildly tachypneic, and hypoxia. He was slightly disoriented. Blood pressure was stable. Cardiac auscultation revealed a systolic murmur, described as previously known. Laboratory tests showed C-reactive protein 63 mg/L, normal leukocyte count, hyponatremia with sodium 128 mmol/L, and mild anemia.
Early Clinical Course and Initial Interpretation
Blood cultures obtained on admission grew Klebsiella pneumoniae in all four bottles within the first 24 hours. Given the presence of a permanent urinary catheter and previous urological disease, the bacteremia was interpreted as secondary to urosepsis, despite negative urine cultures. Antibiotic therapy was escalated to gentamicin and later switched to trimethoprim-sulfamethoxazole.
Computed tomography of the abdomen and pelvis did not reveal a clear infectious focus. Despite appropriate antimicrobial therapy, the patient remained febrile and inflammatory markers showed minimal improvement. A short trial without antibiotics was attempted to assess spontaneous resolution, without clinical benefit.
Clinical Warning Signs
The patient developed worsening confusion. Computed tomography of the head revealed lesions in the left temporal lobe initially interpreted as possible tumor. Subsequent magnetic resonance imaging demonstrated multiple lesions with diffusion restriction and contrast enhancement, consistent with septic emboli.
On repeat clinical examination, a systolic murmur over the aortic area was again noted. In the context of persistent bacteremia, lack of clinical response, and neurological findings, echocardiography was finally performed.
Diagnostic Breakthrough
Transthoracic and transesophageal echocardiography revealed severe pathology. There was infective endocarditis involving the native aortic valve with vegetations, valve destruction, and perforation. Severe aortic regurgitation was present, along with a large aortic root abscess with rupture into the aorta. The left ventricle was markedly dilated and volume overloaded, with mildly reduced systolic function.
Cardiac computed tomography confirmed the findings, including a pseudoaneurysm at the level of the annulus.
The final diagnosis was Klebsiella-associated native aortic valve endocarditis complicated by aortic root abscess and septic cerebral embolization.
Hyponatremia in Sepsis
The patient had developed progressive hyponatremia over several months prior to admission. Hyponatremia is a common complication of sepsis, regardless of the causative microorganism. The underlying mechanisms include increased secretion of antidiuretic hormone, stress response, and iatrogenic factors such as fluid therapy. Several studies have shown that hyponatremia in sepsis is associated with increased risk of complications and mortality and should not be considered a benign laboratory finding.
Discussion
Gram-negative bacilli are an uncommon cause of infective endocarditis, accounting for approximately five percent of cases. When endocarditis caused by Gram-negative organisms occurs, it is often associated with an aggressive course, extensive valve destruction, abscess formation, and embolic complications.
This case highlights several important diagnostic pitfalls. Anchoring on a seemingly plausible infectious focus, in this case the urinary tract, delayed evaluation of the heart. A previously documented murmur was not reassessed in light of new clinical findings. The relatively modest elevation of C-reactive protein may also have contributed to an underestimation of disease severity.
Learning Points
Persistent bacteremia without a clear source should always prompt evaluation for infective endocarditis, regardless of the causative organism.
Gram-negative bacteria do not exclude endocarditis.
Lack of clinical response to appropriate antibiotics is a critical warning sign.
Hyponatremia is common in sepsis and carries prognostic significance.
When the clinical picture does not fit, the working diagnosis must be reconsidered.
Conclusion
This case underscores the importance of clinical vigilance and the willingness to reassess initial assumptions. Infective endocarditis may present atypically, and delayed diagnosis can have severe consequences. Endocarditis should be evaluated early in cases of unexplained bacteremia.
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