July 14, 2018
2 min read

Among ESBL-producing organisms, K. pneumoniae may be deadlier than E. coli

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Jason Burnham
Jason P. Burnham

In a retrospective evaluation of patients at a St. Louis hospital, extended-spectrum beta-lactamase-producing — or ESBL-producing — Klebsiella pneumoniae was associated with a marginally increased risk for 30-day mortality compared with ESBL-producing Escherichia coli, according to findings published in Infection Control & Hospital Epidemiology.

“Not all Enterobacteriaceae are created equal when it comes to prognosis. We have a tendency to lump gram-negative infections together as a group and this research reinforces that that is an artificial construct,” Jason P. Burnham, MD, instructor of medicine in the division of infectious diseases at Washington University School of Medicine in St. Louis, told Infectious Disease News. “A patient with an ESBL K. pneumoniae infection may be more likely to die than if they had an ESBL E coli infection. Further research is needed, but it is possible that these findings may have implications for who gets put on isolation precautions in the hospital.”

Recently, Burnham and colleagues published study findings regarding the mortality, readmission, recurrences and benefits of infectious disease consultations for patients with multidrug resistant EBSL-producing Enterobacteriaceae. In 2017, WHO’s list of priority pathogens ranked carbapenem-resistant and ESBL Enterobacteriaceae among the pathogens with the highest need for research and development of new antibiotic treatment.

In April 2018, results from the INCREMENT study found that patients with ESBL-producing K. pneumoniae had a higher risk for 30-day mortality than patients with ESBL-producing E. coli. Scheuerman and colleagues emphasized that ESBL-producing Enterobacteriaceae are not all part of the same homogenous group. Therefore, Burnham and colleagues conducted a retrospective evaluation of their previous study’s population to determine the association between mortality and the ESBL-producing infections.

The study was conducted at Barnes-Jewish Hospital in St. Louis between Jan. 1, 2006, and Oct. 1, 2015. Burnham and colleagues included any patients with positive sterile site and bronchial wash/bronchioloalveolar lavage cultures for both ESBL-producing Enterobacteriaceae infections. The primary endpoint of the retrospective evaluation was 30-day all-cause mortality.

Of the 605 eligible patients, 543 had ESBL-producing E. coli and 62 had ESBL-producing K. pneumoniae. Within 30 days, 17.7% (n = 96) of patients with ESBL-producing E. coli and 25.8% (n = 16) of patients with ESBL-producing K. pneumoniae died. Kaplan-Meier analysis did not show a significant difference in mortality between patients infected with ESBL-producing K. pneumoniae and E. coli organisms (P = 0.12). In the final Cox proportional hazards model, mortality was marginally associated with ESBL-producing K. pneumoniae infections (HR = 1.69; 95% CI, 097-2.92), the researchers observed.


Burnham and colleagues found a marginally increased risk of 30-mortality associated with K. pneumoniae. They emphasized that, although a post-hoc analysis determined the study underpowered, the data are important to include with the other literature about ESBL-producing K. pneumoniae and E. coli. Additionally, they noted that infectious disease consultation was associated with reduced mortality for drug-resistant Enterobacteriaceae infections.

“The next steps will require inputs from various lines of research. Data from additional centers should be used to verify the association between ESBL K. pneumoniae and increased mortality,” Burnham said. “Simultaneously, people will need to continue their work on figuring out which patients to put on contact precautions for various drug-resistant infections.” – by Marley Ghizzone


WHO. WHO publishes list of bacteria for which new antibiotics are urgently needed. http://www.who.int/news-room/detail/27-02-2017-who-publishes-list-of-bacteria-for-which-new-antibiotics-are-urgently-needed. Accessed July 9, 2018.

Disclosures: Burnham reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.

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