Clinical and microbiological features of bacteraemia with Aerococcus urinae

Abstract

Aerococcus urinae is a Gram-positive bacterium that can cause invasive infection, including infectious endocarditis (IE), mainly in older men. A. urinae is often misclassified in routine diagnostic laboratories. Through searches in the laboratory databases we identify 16 isolates of A. urinae causing bacteraemia during a 6-year period in southern Sweden, indicating that bacteraemia with A. urinae occurs in at least three cases per million inhabitants per year. The identity of isolates was confirmed by sequencing of the 16S rRNA genes and antibiotic susceptibility testing identified two ciprofloxacin-resistant isolates. A. urinae was the only significant pathogen isolated in all cases. Fifteen of the 16 patients were male, 15/16 were more than 70 years old, and 12/16 had underlying urological conditions. Though a urinary tract focus was suspected in the majority of cases, the bacterium was rarely found in urinary samples. Nine patients fulfilled the criteria for severe sepsis and an additional four fulfilled the criteria for sepsis. Only one fatality was recorded. Patients were treated mainly with beta-lactam antibiotics but fluoroquinolones and clindamycin were also used. Three cases of IE were diagnosed and these were complicated by spondylodiscitis in one case and by septic embolization to the brain in one case. An increased awareness of A. urinae is crucial to establishing its role as an important pathogen in older men with urinary tract disease.

Clinical and microbiological features of infective endocarditis caused by aerococci

“…The patients were predominantly male (12/16) and the median age was 79 years. Two patients have been previously reported [7,10]. Fourteen patients fulfilled the revised Dukes criteria for definite IE [22] whereas two patients had possible IE.…”

“…Severe sepsis was defined as described in [7]. Data from the SRIE on IE caused by enterococci, alpha-haemolytic streptococci, and …”

“…Aerococcus urinae is the most common aerococcal species isolated in IE [6,7,8] whereas Aerococcus sanguinicola is more rarely encountered [9,10]. Aerococcus viridans was the first aerococcal species to be identified but is a rare cause of human infections [2,11].…”

“…Patients with A. urinae IE are typically older males with underlying urinary tract diseases [2,6,7,8,17]. Of four described cases of IE with A. sanguinicola, one fatality was reported [9,10].…”

“…We have previously performed population-based studies which showed that only three of sixteen patients with A. urinae bacteremia and two of eleven patients with A. sanguinicola bacteremia had IE. All five patients with IE described in these studies survived their infection despite significant underlying diseases [7,10]. The optimal treatment of aerococcal IE has not been determined, but two studies have suggested 4 that penicillin and aminoglycosides have synergistic effect on aerococci in vitro [17,21] and therefore combination therapy has been used in most cases.…”