Methods: Case report and literature review. Informed consent was obtained from the patient (forms available for review).
Results: A 60-year-old man with uncontrolled diabetes mellitus presented with two weeks of right knee swelling and pain after twisting his knee. One week prior to admission, the patient received an intra-articular injection of triamcinolone for presumed osteoarthritis. Post-procedure, symptoms persisted. Two days prior to admission, he developed fevers prompting his presentation to the emergency room.
In the ER, the patient was febrile, tachycardic, and hypertensive. Exam revealed a prominent effusion with overlying warmth and erythema. Labs showed a leukocytosis (12.3 WBC/nL) with an elevated ESR (52) and CRP (141). An arthrocentesis revealed serosanguinous fluid with a cell count of 33,000 WBCs (/mm3) and 89% PMNs. Initial gram stain was negative. He was started on intravenous vancomycin and ceftriaxone, however remained febrile with an unchanged exam. An arthroscopic knee washout was performed with improvement in clinical exam and inflammatory markers. On hospital day #5, initial culture from the ED started to grow gram negative bacilli. On hospital day #14, cultures speciated to Neisseria elongata with β-lactamase activity. The patient was eventually discharged on doxycycline and ciprofloxacin for a 4-week course.
Conclusion: N. elongata is an oxidase positive, catalase negative organism normally found in the pharynx. Generally non-pathogenic, it has been associated with cases of septic arthritis and endocarditis. Only two case reports have linked N. elongata to septic arthritis; one case occurring after an intra-articular injection. Both cases involved the sternoclavicular joint and neither reported β-lactamase activity. Our case represents the first reported patient to have developed knee septic arthritis from β-lactam resistant N. elongata. Unusual pathogens should be considered in patients with a clinical picture of septic arthritis and fastidious culture growth.
H. Park, None
J. Chun, None
S. J. Yoo, None
M. S. L. Lee, None
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