Title : Citrobaacter Braakii: The 21st century mystery pathogen still keeping us guessing
Abstract:
Introduction: Citrobacter braakii is a gram-negative bacterium that is part of the Enterobacteriaceae family. While Citrobacter species are known to cause a variety of infections, including urinary tract infections, bacteremia, and meningitis, there is limited specific literature directly linking Citrobacter braakii to pericardial effusion. We report one such case of citrobacter braakii causing pericardial effusion in an immunocompromised patient. This case report aims to shed light on an unusual presentation of Citrobacter braakii, linking it to pericardial effusion, a manifestation not previously well-documented.
Case Presentation: The patient is a 73-year-old female with past medical history of ESRD, renal transplant 8 years ago on immunosuppressive therapy with tacrolimus and mycophenolate mofetil leading to subsequent CKD, and has history of multiple hospitalizations in the past for heart failure exacerbations. Prior to her most recent hospitalization, her diuretic was suspended by the cardiologist during her regular office visit as there was concern for further worsening of kidney function.
Shortly after, she presented to the hospital with worsening lower extremity edema, fatigue and weight gain of over 6 kgs in the span of 1 week. Initial physical exam findings were pertinent for JVD, bilateral lower extremity edema and an irregular heart rhythm of 105 bpm. Initial evaluation included a bedside echocardiogram which revealed a large pericardial effusion associated with moderate mitral regurgitation and moderate tricuspid regurgitation without any evidence of tamponade physiology. Labs significant for elevated creatinine 2.5 mg/dL.
Management: Due to concerns of preload dependency, there were no plans for initiating diuretic therapy. The initial attempt of pericardiocentesis was unsuccessful. Subsequent imaging with CT of the chest confirmed the presence of a large pericardial effusion with small bilateral pleural effusions and adjacent atelectasis. As she continued to worsen clinically with increasing respiratory distress, the decision was made to perform a pericardial window. She underwent the procedure under general anesthesia. 400 cc of turbid fluid was drained and the pericardial fluid was sent for culture and sensitivity. Empiric IV antibiotics with cefazolin and vancomycin were initiated during the procedure. Subsequent cultures revealed growth of Citrobacter braakii, prompting a change to meropenem due to the patient's immunocompromised status.
Complications: The patient subsequently developed septic shock characterized by hypotension and tachycardia requiring aggressive IV fluid resuscitation and vasopressor support with Nor epinephrine and was transferred to ICU. Her hospital course was further complicated by the development of sudden-onset right-sided weakness and expressive aphasia. MRI of the brain revealed extensive multifocal bilateral supratentorial and infratentorial acute to subacute infarctions, suggestive of a central embolic event. A transesophageal echocardiogram was planned to evaluate potential cardiac sources of embolism, particularly given her history of atrial fibrillation. No embolic source was identified.
Patient subsequently was weaned off pressors and fluids. A PICC line was placed for long-term administration of antibiotics. Her antibiotics were subsequently de-escalated to IV ceftriaxone with follow-up negative cultures.
Discussion: There is very limited data regarding the varied presentations of citrobacter braakii, as seen in our case, it can lead to pericardial effusion and severe sepsis warranting long term antibiotic course. The epidemiology and characteristics of citrobacter braakii has not been studied secondary to limited diagnostic identification and this necessitates further research and better diagnostic methods for prompt identification and treatment.
