Multi-drug resistant (MDR) infections are a public health threat and cause significant morbidity and mortality among hospitalized patients. There are typically limited antibiotic treatment options for MDR infections making their management more difficult. Our study assessed for markers of disease severity and treatment outcomes of patients with daptomycin non-susceptible VRE (DNSVRE) compared to those with daptomycin susceptible VRE (DSVRE) bacteremia.
This was a retrospective 2:1 age, sex, and clinical syndrome-matched cohort study of patients with DNSVRE and DSVRE bacteremia over a four year period at the Yale-New Haven Health System (January 2010 - December 2013). Non-susceptibility of VRE to daptomycin was defined as isolates with a MIC > 4µg/ml per CLSI guidelines. Patient outcomes including SIRS presentation, requirement for ICU stay, pressors and ventilator support, as well as mortality up to 30 days post-discharge were captured. Fischer’s exact and Pearson’s chi-squared tests as appropriate were used to assess for differences in categorical variables.
There were 10 cases of DNSVRE and 19 matched cases of DSVRE bacteremia with a median age of 60 years and they comprised 70% and 74% male patients respectively. Majority (70%) of cases had gastrointestinal infections as a source of bacteremia. More DNSVRE cases had underlying malignancies (90% vs 53%, p=0.046). More patients with DNSVRE bacteremia met SIRS criteria, required ICU stay, and renal replacement, but those differences were not statistically significant. Mortality up to 30 days post-discharge was higher but not statistically significant for DNSVRE cases (70% vs 47%, p=0.163). We observed a “MIC creep” phenomenon where the majority of patients with DNSVRE isolates (60%) had isolates that were initially susceptible to daptomycin but became more resistant following antibiotic exposure.
The severity of infection and mortality of patients with DNSVRE bacteremia were worse but not statistically different from that observed among their counterparts with DSVRE. Patients with DSVRE infections who do not respond to treatment should be assessed for changes in daptomycin susceptibility.
O. Ogbuagu, None
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