Physician Rush University Medical Center, United States
Background: The adult CF microbiome is typically dominated by Pseudomonas aeruginosa (PA). The introduction of highly effective modulator therapy (HEMT) has been associated with decreased sputum production and data is emerging regarding the impact on the adult CF microbiome. We hypothesized that HEMT would have a beneficial impact on both the ecology and the susceptibility pattern of the airway microorganisms in adult patients with CF.
Methods: Adult (≥ 18 years old) patients seen at the RUMC CF center who received HEMT for at least 4 months were included. Sputum cultures were collected as part of routine CF care, the last culture prior to starting HEMT was considered baseline. Subsequent sputum cultures were obtained during in-person visits, as per guidelines. For the current project, only cultures positive for PA and mucoid PA were included. Antibiotic susceptibility results were noted for each positive PA culture. Simple descriptive data were used to report changes observed in antibiotic susceptibility before and after HEMT therapy.
Results: 14 adult patients with CF had PA growing in their sputum prior to starting HEMT; 21% were no longer positive after initiation of HEMT and sputum grew normal respiratory microbiota. Among the patients who continued to have a positive PA sputum or throat culture, all isolates remained susceptible to meropenem and piperacillin/tazobactam, 71% remained susceptible to ceftazidime and cefepime, and 21% remained susceptible to levofloxacin. Additionally, 50% demonstrated an improvement in antibiotic susceptibility, the most common change was changing from resistant to sensitive to amikacin. Others demonstrated a change from resistant to sensitive for ceftazidime; resistant to intermediate for gentamicin, levofloxacin, and tobramycin; and intermediate to sensitive for cefepime. 22% remained resistant to amikacin and 14% remained resistant to gentamicin and levofloxacin. Finally, 29% had a decreased antibiotic susceptibility; the most common finding was changing from sensitive to resistant for gentamicin, tobramycin, and cefepime.
Conclusions: The majority of PA colonized adult patients with CF treated with HEMT had a decrease in the colonization rate of PA and an improvement in the antibiotic susceptibility to common antibiotic therapy. Larger studies are needed to confirm this potential positive impact on the microbiome of the adult CF patient receiving HEMT.
