Outcome of Listeria monocytogenes prosthetic valve endocarditis: as bad as it looks?

In 1998 we presented 1 successfully treated case of Listeria monocytogenes prosthetic valve endocarditis and made a review of all the cases that had been published to date. We carry out an up-to-date review through Pub-Med of every case of Listeria monocytogenes prosthetic valve endocarditis; mortality rate is calculated and data from several clinical and therapeutical variables are collected; Fisher's exact test is used to identify those variables significantly associated with mortality. Four out of 23 patients died in hospital (17%); among all the variables included, only peripheral embolism (p=0.024), onset on a mechanical prosthesis (p=0.035) and having used only 1 antibiotic instead of a combination of drugs (p=0.026) were independently associated with mortality. Although the overall number of cases is too low to draw definite conclusions (n=23), mortality rate is lower than previously believed. Some variables that have traditionally been associated with a poor prognosis for endocarditides are not for the case of Listeria monocytogenes on valvular prostheses. It seems prudent to treat affected patients with a combination of ampicillin -- or vancomycin, if there is a history of beta-lactam allergy and ampicillin desensitization is not possible -- plus an aminoglycoside.