Patients with Carbapenem-Resistant Bloodstream Infections Less Likely to Survive Hospitalization

New research presented by investigators at ID Week 2018 found that patients with carbapenem-resistant bloodstream infections had a reduced likelihood of surviving hospitalization or being discharged home, underscoring the need for stronger prevention and treatment strategies.

Bloodstream infections (BSIs) caused by gram-negative bacteria are known to cause significant morbidity and mortality. With increasing incidence of antibiotic-resistant bacteria among the culprits causing these infections, they pose a significant therapeutic challenge for health care providers.

In order to glean a better understanding of the incidence of carbapenem-resistance among patients with BSIs in hospitals across the United States, a team of investigators assessed the characteristics and outcomes of adult patients 18 years of age or older who had a positive blood cultures for gram-negative pathogens and susceptibility tests for the 11 most prevalent gram-negative pathogens.

The investigators used the Premier Research Healthcare Database, which collects patient-level data from upwards of 700 US hospitals on an annual basis. Microbiology test results such as specimen site, pathogen, and drug susceptibility were provided by a subset of 181 hospitals.

For the retrospective cohort analysis, the investigators compared patients who had carbapenem-resistant BSIs with patients who had carbapenem-susceptible BSIs. The primary outcome of the study was mortality, while secondary outcomes included post-index culture, hospital and intensive care unit (ICU) lengths of stay, and the likelihood of being discharged home.

The investigators found that of about 53,811 patient samples, 46,381 of the patients had a gram-negative BSI; the rate of carbapenem resistance in these samples was 3.5% (n = 1602). Patients with carbapenem-resistant infections were younger (mean/standard deviation (SD) 60.4/17.1 vs 67.4/16.4 years, P<.0001), had increased likelihood of being male (52.8% vs 45.9%, P<.0001), black (22.7% vs 17.7% P<.0001), and have Medicaid (18.1% vs 10.9%, P<.0001) compared with patients who had carbapenem-susceptible BSIs.

In those patients with carbapenem-resistant BSIs the mean/SD Charlson Comorbidity Index was higher than those with carbapenem susceptible BSIs (2.9/2.5 vs 2.3/2.5, P<.0001).

Patients with carbapenem-resistant BSIs were also found to have higher mortality (20.6% vs 9.7%, P<.01) and longer length of stays in the hospital (9 [6, 15] vs 7 [5, 10] days, P<.0001) and in the ICU (5 [2, 11] vs 3 [2, 6] days, P<.0001) compared with those who had carbapenem-susceptible BSIs; this population was also not as likely to be discharged home as those with carbapenem susceptible BSIs (32.7% vs 53.8%, P<.001).

“Patients with carbapenem-resistant BSIs have lower likelihood of surviving hospitalization or being discharged home, and longer post-index culture hospital and ICU [length of stay], compared with those with carbapenem-susceptible BSIs,” study authors concluded.

Their findings underscore the need for improved prevention and treatment strategies developed specifically for fighting gram-negative carbapenem resistance.