COPD Outpatients with P Aeruginosa Colonization Have Greater Risk of Mortality

Pseudomonas aeruginosa (PA) infection put outpatients with chronic obstructive pulmonary disease (COPD) at a 47% higher risk of mortality than those who didn’t have the tracheobronchial infection, a new study found.

In the study, published in Open Forum Infectious Diseases, investigators at University at Buffalo examined all-cause mortality of COPD patients from 1994 to 2014 at the Buffalo VA Medical Center.

It found that PA was isolated from the sputum of 40% of patients (73 of 181), and that mortality was significantly higher in those patients, with 77% dying compared with 68% of patients without PA. Using Cox proportional hazards models, the PA+ group was found to have a 47% higher risk of mortality than those in the PA- group.

“We feel the biggest takeaway from our study is the significantly higher risk of mortality among COPD outpatients with P aeruginosa isolation,” David M. Jacobs, PharmD, PhD, assistant professors in the School of Pharmacy and Pharmaceutical Sciences at the University at Buffalo told Contagion^®. “This is one of the first studies presenting data that support an association between tracheobronchial colonization by P aeruginosa in COPD outpatients with higher morbidity and mortality.”

The study also found higher exacerbation rates and hospitalization rates among COPD patients with PA colonization. Exacerbation rates during pre-isolation periods were 15.4 per 100 person-months among PA+ patients compared with 9.0 among PA- patients. During post-isolation rates, exacerbation rates were 15.7 vs. 7.5. Hospitalization rates were 6.25 hospitalizations per 100 person-months among PA+ patients vs. 2.44 among PA- patients.

“Our research shows an association between P aeruginosa isolation and poor clinical outcomes. For COPD outpatients, clinicians and healthcare providers may want to pay closer attention to those patients that isolate Pseudomonas,” Jacobs told Contagion^®. “This may be an opportunity to use this finding as a biomarker for closer patient follow-up.”

Previous studies among patients hospitalized with COPD exacerbations have found that P aeruginosa isolation was associated with higher mortality. This study examined the risks among patients in an outpatient setting.

The study noted that the PA+ group saw a higher rate of antibiotic and oral steroid treatments than the PA- group and higher total antibiotic exposure.

“Additional research is needed especially prospective randomized studies in order to validate our findings,” Jacobs told Contagion^®. “As research on this topic continues, early intervention for P aeruginosa isolation may be proposed in order to minimize long-term sequelae.”

The study is limited by the small size of the cohort and the fact that it was conducted as a single health center, but most other studies have had similar sizes.

The study noted that P aeruginosa is likely a driver rather than a marker of worsening disease based on its association with adverse clinical outcomes including higher rates of exacerbations and hospitalizations.

Early diagnosis and treatment of P aeruginosa is necessary to limit risks.

P aeruginosa is among the pathogens for which antimicrobial resistance is a concern. As a result, it has been a focus of drug development in recent years, including the addition of imipenem/cilastatin/relebactam and cefiderocol.

Chronic conditions including COPD have respiratory symptoms that are often mistaken for infection, according to a recent study that found that antibiotic use increased significantly in the months leading up to a diagnosis.