ABSTRACT
BACKGROUND: Antibiotic
therapy is essential for the treatment of cystic fibrosis (CF) lung
infections. CF-specific airway pathophysiology and frequent
antimicrobial exposure increase the risk of resistant infections,
creating challenges to antibiotic selection. Antibiotic selection is
generally based on previous cultures or hospital-wide antibiograms
(HWA); however, most HWA exclude CF isolates. We developed a multi-year
CF antibiogram (CFA) to compare with HWA and inform antibiotic
selection.
METHODS: CF culture data were collected 2015 - 2019 at a single
pediatric CF center. All sputum and oropharyngeal swab isolates are
included in the CFA. Demographics, microorganism isolates, and
susceptibility information are presented. Susceptibilities were reported
for methicillin-susceptible Staphylococcus aureus (MSSA),
methicillin-resistant Staphylococcus aureus (MRSA),Pseudomonas aeruginosa (PA), Achromobacter species,Burkholderia species and Stenotrophomonas maltophilia.
RESULTS: Over five years, the proportion of all SA isolates
having methicillin-resistance was higher in the HWA (32%) than the CFA
(28%). The most common gram-negative CF isolate was PA. Both
gram-positive and gram-negative microorganisms were less susceptible in
the CFA versus the HWA. CF isolates from sputum were less susceptible
than oropharyngeal. MSSA and MRSA had significantly lower clindamycin
susceptibility in the CFA compared to the HWA (MSSA 71% vs 79%,
p<0.0001 and MRSA 39% vs 83%, p<0.0001). For every
antimicrobial tested, PA isolates were less susceptible in the CFA
compared to the HWA. There did not appear to be significant changes in
susceptibility of CF isolates over time.
CONCLUSIONS: These findings have clinical implications for
empiric antimicrobial selection. A CFA will allow monitoring of
resistance over time.