Intracellular Escherichia coli in urinary malakoplakia: a reservoir of infection and its therapeutic implications.

Urinary malakoplakia may pursue an aggressive clinical course with persistent infection, despite seemingly appropriate antibiotic therapy. The authors studied seven adult females with urinary malakoplakia. Specific immunocytochemical staining demonstrated intracellular Escherichia coli in malakoplakia tissue in four patients. In two of the four patients, the bacteria were present despite antibiotic-induced sterile urines at time of biopsy. Cessation of therapy consistently lead to recurrent bacteriuria in these patients. In one such patient, the intracellular bacilli were confirmed as E. coli by culture of crushed malakoplakia tissue and electron microscopic study; the organisms were a routine E. coli strain susceptible to multiple previously administered antibiotics. Only sequential treatment with bethanechol chloride and trimethoprim-sulfamethoxazole, however, eliminated the infection; all three drugs are thought to be capable of enhancing intracellular killing of bacteria. Conventional antibiotic therapy failed to halt progression of disease in other malakoplakia patients. The data indicate that intracellular bacteria may serve as a reservoir of persistent/recurrent infection in urinary malakoplakia. Optimal therapy should include therapeutic agents that may control intracellular organisms.