C69-03 A Cat-astrophic Infection: Multifocal Pneumonia From Bartonella Henselae After Renal Transplantation

Abstract Introduction Cat scratch disease, caused by the gram-negative bacterium Bartonella henselae, most commonly presents in children and older adults as a self-limiting cutaneous infection with regional lymphadenopathy after kitten exposure. However, immunocompromised patients may have atypical or disseminated disease delaying diagnosis and treatment. We describe a case of multifocal pneumonia caused by Bartonella henselae in a renal transplant recipient. Case Presentation A 40-year-old male with diabetes and end-stage renal disease, status post deceased-donor kidney transplant, presented to the emergency department with 3 days of progressive malaise, nausea, and vomiting. Initial management targeted acute kidney injury and metabolic acidosis (presumed starvation or euglycemic diabetic ketoacidosis). He subsequently developed fever, leukocytosis, and hypoxic respiratory failure, prompting initiation of vancomycin and cefepime. Declining respiratory function led to ICU transfer for non-invasive ventilation. CT chest revealed scattered bilateral nodular and patchy ground-glass opacities, basilar consolidations, bilateral pleural effusions, and pulmonary edema. Antibiotics were escalated to meropenem, azithromycin, and micafungin along with trimethoprim-sulfamethoxazole for empiric Pneumocystis jiroveci coverage. Blood, sputum, and urine cultures remained negative. Bronchoscopy was deferred due to high oxygen requirements. Serum microbial cell-free DNA (mcf-DNA) testing returned positive for B. henselae later confirmed by serologic testing (B. henselae IgM 1:320, IgG 1:512), respectively) with a negative PCR. Additional history revealed exposure to six household cats, though the patient denied any recent scratches or bites. Antibiotics were optimized to doxycycline and gentamicin. Further workup showed ill-defined hyperintense splenic lesions on abdominal MRI concerning for disseminated disease, while transesophageal echocardiogram and ophthalmologic exam were negative for endocarditis or ocular involvement. The patient’s clinical status improved and he was discharged on combination therapy with doxycycline and azithromycin with continued improvement at follow-up. Discussion Lung involvement in B. henselae is rarely reported. While serology and PCR can confirm infection, timely diagnosis may be limited by test availability and sensitivity. This case underscores the importance of maintaining a broad index of suspicion for infectious etiologies in immunocompromised patients and highlights the diagnostic value of mcf-DNA in patients with fever and sepsis of unknown origin, enabling early recognition and targeted therapy for atypical infections with atypical presentations. This abstract is funded by: None