Antimicrobial drug resistance in salmonella-infected aortic aneurysms

Background. Salmonella infection of the aorta and adjacent arteries is rare, but life-threatening. There is an increasing number of infections caused by antimicrobial drug resistant Salmonella. This study sought to assess the association between antimicrobial drug resistance and clinical outcomes of patients with Salmonella-infected aortic aneurysm. Methods. Data were collected by retrospective chart review. Between October 1995 and October 2004, 34 patients with Salmonella-infected aortic aneurysm were included. Aneurysm-related deaths were defined as hospital deaths and late deaths due to prosthetic graft infection. Analysis was performed using the χ² test, Fisher's exact test, and Mann-Whitney test. Results. Nineteen patients had a suprarenal and 15 patients had an infrarenal aortic infection. The most common responsible pathogen was group C Salmonella (47%). Ciprofloxacin- resistant Salmonella infection occurred since March 2001 and the rate increased from 0 per 15 in the years before March 2001 to 5 per 19 in the years after March 2001 (p = 0.005 by Fisher's exact test). Among the 26 patients who had combined medical and surgical therapy, 4 died in the hospital and 4 died of late prosthetic graft infection 3 to 6 months after operation, whereas 4 of the 8 who had medical therapy alone died of aneurysm rupture during hospitalization. The actuarial survival rates by the Kaplan-Meier method were 64% at 6 months, 61% at 1 year, and 56% at 5 years. The risk factors for aneurysm-related death were old age (78.5 ± 9.7 years vs 63.5 ± 11.4 years; p < 0.001) and ciprofloxacin-resistant Salmonella infection (4 of 5 vs 8 of 29; p = 0.042). Conclusions. There was an increased mortality associated with ciprofloxacin resistance in infected aortic aneurysms with Salmonella. With an increasing incidence of ciprofloxacin resistant Salmonella, third generation cephalosporin is the antibiotic of choice for Salmonella-infected aneurysm.