NEW ORLEANS – Investigators discovered significant differences in risk factors when comparing 603 people hospitalized with carbapenem-resistant Gram-negative sepsis with either Enterobacteriaceae-caused or non-Enterobacteriaceae–caused infection.
“We know some of the virulence factors and the resistance mechanisms can differ between those two groups. We really wanted to see if that would influence outcomes,” said Nicholas S. Britt, PharmD, a PGY2 infectious disease resident at Barnes-Jewish Hospital in St. Louis. Mortality rates, however, did not differ significantly.
©CDC/ Melissa Brower
“Patients who had Enterobacteriaceae infections were more likely to have urinary tract infections, to be older patients, and to have higher APACHE (Acute Physiologic Assessment and Chronic Health Evaluation) II scores,” Dr. Britt said at the annual meeting of the American Society for Microbiology. These differences all were statistically significant, compared with those of the CRNE group (P less than .05).
In contrast, the non-Enterobacteriaceae patients tended to have more respiratory infections and more frequent central venous catheter use. This group also was more likely to have a history of carbapenem use and more frequent antimicrobial exposures overall and to present after solid organ transplantation. “The cystic fibrosis patients were more likely to get non-Enterobacteriaceae infections as well,” Dr. Britt added. These differences also were statistically significant (all P less than .05).
“I think the biggest takeaway from this study, honestly, is the number of patients infected with CRE, versus CRNE,” Dr. Britt said. “We know CRE are a serious public health threat, one of the biggest threats out there, but, if you look at the burden on carbapenem-resistant disease, it’s primarily the non-Enterobacteriaceae.”
In fact, more than three-quarters of the patient studied (78%) had CRNE infections, and Pseudomonas was a major driver, he added. “Carbapenem resistance in this group of patients is something we should be focusing on – not only the CRE – because we’re seeing more of the non-CRE clinically.”
Patient age, presence of bloodstream infection, and use of mechanical ventilation, vasopressors, and immunosuppression was associated with hospital mortality in the study. After adjusting for potential confounders, however, CRNE infection was not associated with increased hospital mortality, compared with CRE cases (adjusted odds ratio, 0.97; P = .917).
“Our mortality rate was 16%, which is comparable to [that of] other studies,” Dr. Britt said. “There doesn’t seem to be any difference in this outcome between the two groups.” Mortality was 16.4% in the CRE cohort, versus 16.5% in the CRNE cohort (P = 0.965).