The emergence of Klebsiella pneumoniae endogenous endophthalmitis in the USA: basic and clinical advances

Endogenous endophthalmitis (EE) is a rare but devastating infection that occurs secondary to seeding of the intraocular cavity from an extraocular focus. Recent reports suggest the increasing prevalence and incidence of Klebsiella pneumoniae as a causative organism in Asian countries. Analysis of the largest cohorts published to date suggests that K. pneumoniae endogenous endophthalmitis (KPEE) is 10 to 15 times more prevalent than other causes of EE. The incidence of KPEE among patients with systemic Klebsiella infection appears to be > 100-fold more common than other causes of EE. The exact reason for these observations is not clear, but a number of studies now suggest that Klebsiella serotypes K1 and K2 have virulence factors that enhance their survival in diabetic patients and increase their pathogenicity. Here, we report two cases of KPEE in the USA. We also review the recent clinical and basic science literature on the prevalence, incidence, and pathophysiology of this emerging and devastating infection.