Assistant Professor University of Michigan, United States
Background: Chronic airway infections with Pseudomonas aeruginosa are significant contributors to morbidity and mortality in people with cystic fibrosis (pwCF). The understanding of epidemiology and clinical outcomes of P. aeruginosa infection has led to recommendations for P. aeruginosa eradication for early infection, and management strategies for chronic infection. These interventions have led to reduced rates of chronic P. aeruginosa infection, and improved outcomes for pwCF. Much less is known about the clinical impact of other Pseudomonasspp. in pwCF, and it is unclear if these infections should be managed similarly to P. aeruginosa. The objective of this study was to determine the epidemiology and outcomes of Pseudomonas spp. other than P. aeruginosa in pwCF.
Methods: This was a single center, retrospective study of pwCF with one or more airway cultures positive for a Pseudomonas spp. (other than P. aeruginosa) from 2014-2021. Medical records were reviewed for demographic and clinical data, and descriptive statistics were used. Clinical outcomes over the two-year period following incident Pseudomonas spp. infection were evaluated and included microbiological culture results, changes in lung function, and number of pulmonary exacerbations.
Results: We identified 194 airway cultures positive for Pseudomonas spp. other than P. aeruginosa from 135 pwCF. Prevalence of Pseudomonas spp. at our CF center was ~4% of pwCF annually. The median age of incident infection with Pseudomonas spp. was 13.1 years (range 0.2–78.6 years). The majority (56%) of the patients were female. 41% were homozygous for F508del, and 41% were heterozygous for F508del. The majority (63%) of cultures positive for Pseudomonas spp. were from oropharyngeal swabs, 36% were from sputum samples, and 1% from bronchoalveolar lavage. P. fluorescens was the most prevalent identified species (36% of cultures), followed by P. putida (24%), P. koreensis (4%), and P. oryzihabitans (4%). 32% of cultures were Pseudomonas spp, not further identified. 18% of patients had multiple positive cultures of at least one Pseudomonas spp, with a median of 2 positive cultures (range 2–8). 29% of patients had cultures positive for more than one Pseudomonas spp.
Conclusions: In this single center, retrospective study, Pseudomonas spp. other than P. aeruginosa were low in prevalence rate in pwCF, and P. fluorescens was the species most often identified. Most positive cultures were transient, and did not lead to chronic Pseudomonas spp. infection. Ongoing work in this cohort is evaluating associations between Pseudomonas spp. and other CF pathogens including P. aeruginosa, clinical outcomes including changes in lung function and pulmonary exacerbation rate following Pseudomonas spp. infection, and the potential impact on anti-pseudomonal treatment.
Acknowledgements: This work was supported by CFF First and Second Year Clinical Fellowship [AWD: 015509]
