Polymerase Chain Reaction Detection of Culture-Negative Klebsiella pneumoniae Endophthalmitis: A Case Report

For cases of culture-negative endophthalmitis, 16S ribosomal deoxyribonucleic acid (16S RNA) real-time polymerase chain reaction (RT-PCR) may offer greater diagnostic yield than traditional microbial cultures. Our case presents an unusual clinical course, which supports the use of 16S RNA RT-PCR, even after negative microbial cultures, to secure a pathogenic diagnosis.

A 49-year-old male with human immunodeficiency virus (HIV) infection presented with fever and cough, accompanied by acute bilateral vision reduction, photophobia, and eye pain. Clinically, his examination showed severe panuveitis in both eyes. Investigations showed elevated white blood cells, C-reactive protein, cluster of differentiation 4 count of 180/μL, HIV viral load of <40 copies/mL, and unexpectedly, aqueous and blood cultures were negative. An autoimmune workup was also negative. Given this, intravitreal antibiotics were administered alongside systemic antibiotics. Subsequent chest computed tomography showed pulmonary cavitations and liver lesions, and despite negative culture results, a 16S rRNA RT-PCR of the aqueous humor detected Klebsiella pneumoniae genetic material. The patient completed 6 weeks of ceftriaxone and multiple bilateral vitrectomies for recurrent retinal detachments, likely due to retinal necrosis.

Clinicians may consider alternative etiologies after a negative microbial culture. This teaching case supports the use of 16S RT-PCR to more rigorously rule out infectious causes of panuveitis, especially in immunocompromised patients, to avoid premature consideration of other differential diagnoses.