Risk factors for acquiring ampicillin-resistant enterococci and clinical outcomes at a Canadian tertiary-care hospital

Abstract

The number of ampicillin-resistant enterococci (ARE) was noted to be increased at our teaching hospital. To determine the risk factors for acquiring this organism and to compare clinical outcomes, over a 5-month period 38 patients infected or colonized with ARE were compared with 76 patients infected or colonized with ampicillin-susceptible enterococci (ASE). Risk factors included nosocomial acquisition, duration of hospitalization, admission to a medical service, prior antimicrobial therapy, and combination therapy for at least 7 days. The mortality rate of patients infected or colonized with ARE was higher than that of patients infected or colonized with ASE (34 versus 14%; P = 0.03), but most deaths did not appear to be related to enterococcal infection. Over a 2-year period, 16 patients with ARE bacteremia were also compared with 23 patients with ASE bacteremia. The risk factors associated with ARE bacteremia also included nosocomial acquisition, duration of hospitalization, and prior antimicrobial therapy. The mortality of patients with ARE bacteremia was also higher than that of patients with ASE bacteremia (81 versus 30%o; P = 0.003), with most deaths being due to the underlying disease or a complication of it. Typing ofARE isolates by pulsed-field gel electrophoresis showed that two genotypes predominated in our institution. A prolonged hospital stay, exposure to multiple antimicrobial agents, and perhaps nosocomial transmission are important factors in acquiring ARE. The presence of ARE may also be a marker for poor outcome.

Enterococcal Bacteremia in a Tertiary Care Centre in Winnipeg

“…E faecalis was the dominant species isolated in 85% of episodes, a finding consistent with other reports (20,28). However, several studies also report a predominance of E faecium (27,29) or a shift to E faecium with increasing resistance (30,31). Infections were usually hospital acquired after prolonged hospitalization, as other studies have consistently reported (20,21,29,30,32,33).…”

“…However, several studies also report a predominance of E faecium (27,29) or a shift to E faecium with increasing resistance (30,31). Infections were usually hospital acquired after prolonged hospitalization, as other studies have consistently reported (20,21,29,30,32,33). The characteristics of infected patients, including old age, multiple underlying comorbidities, almost 90% with instrumentation and recent or current antimicrobial therapy, are also consistent with these previous reports.…”

Enterococcal bacteraemia: predictive and prognostic risk factors for ampicillin resistance

“…strains [13]. Several studies have reported an association between the incidence of ampicillin-resistant enterococci and the prior administration of penicillins, cephalosporins, β-lactams, imipenem and fluoroquinolones [13,18,[29][30][31][32]. The prognostic factors for 30-day mortality in patients with both E. faecalis and E. faecium bacteraemia were increased PBS and bacteraemia from an unknown source.…”

In Vitro Activities of 15 Antimicrobial Agents against Clinical Isolates of South African Enterococci

“…Without exception, kanamycin MICs for all kanamycin-resistant isolates were Ն1,024 g/ml, indicating high-level amikacin resistance probably attributable to the liberal use of amikacin in local teaching hospitals (20). The high incidence of ampicillin-resistant E. faecium isolates (35 of 47) might in turn be linked to the frequent prescription of expanded-spectrum cephalosporins for hospitalized patients (12). These results contribute to existing evidence that older antimicrobial agents are progressively losing their efficacy against the enterococci.…”