Algorithm Developed to Identify Carbapenem Resistance Outcomes in Pneumonia

Pseudomonas aeruginosa
Pseudomonas aeruginosa
A novel algorithm has been developed to analyze the epidemiology and outcomes of carbapenem resistance in patients with hospital-acquired and ventilator-associated pneumonia.

A novel algorithm has been developed to analyze the epidemiology and outcomes of carbapenem resistance (CR) in patients with hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP). A retrospective cohort study on the subject was conducted within the Premier Research Database from 2009 through 2016, and published in CHEST.

With the application of a novel algorithm, investigators sought to examine the epidemiology and outcomes of CR in gram-negative pathogens observed in HAP and VAP. They included all hospitalized adult patients with a gram-negative organism in a blood or respiratory culture who fit the criteria for HAP or VAP, according to International Classification of Diseases 9-Clinical Modification codes.

Of a total of 8969 patients with HAP/VAP, 11.8% (1059) of the isolates exhibited CR. Those individuals with CR organisms were significantly more likely to be women (41.4% vs 33.2%, respectively; P <.001) and to have a medically documented hospital admission (34.8% vs 27.4%, respectively; P <.001) compared with those who had carbapenem-susceptible (CS) organisms.

Participants with CR had a significantly higher comorbidity burden than those with CS (median Charlson Comorbidity Index, 3.0±1.4 vs 2±1.4, respectively; P <.001). Pseudomonas aeruginosa was the most common gram-negative pathogen detected overall (21.1%), which was followed by Klebsiella pneumoniae (17.3%) and Escherichia coli (14.9%). Of the CR pathogens, P aeruginosa was responsible for only 16.8% of the organisms identified, whereas a greater percentage of CR infections were caused by Stenotrophomonas maltophilia (38.7%).

Furthermore, although more than one-third of Acinetobacter baumannii were CR, this particular pathogen accounted for only 11.8% of CR infections and 2.5% of CS infections (P <.001). Overall, patients with CR were significantly more likely than those with CS to receive inappropriate empiric therapy (25.8% vs 10.0%, respectively; P <.001). CR did not affect adjusted mortality (CR, 22.9% vs CS, 21.6%) or postinfection length of hospital stay (except in survivors of VAP), but was related to excessive costs ($8921; 95% CI, $3864 to $13,977; P <.001).

The investigators concluded that their novel algorithm identified patients with pneumonia in administrative data who are at high risk for death, which is consistent with HAP and VAP. In these individuals, CR was reported in 12% of all cases and was linked to a substantial excess in hospital costs.

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Disclosures: Several authors report financial relationships with pharmaceutical companies. For a full list of disclosures, please visit the reference.


Zilberberg MD, Nathanson BH, Sulham K, Fan W, Shorr AF. A novel algorithm to analyze epidemiology and outcomes of carbapenem resistance among patients with hospital-acquired and ventilator-associated pneumonia: a retrospective cohort study [published online January 24, 2019]. CHEST. doi:10.1016/j.chest.2018.12.024