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<h5 class="section-title" id="d3281404e185">Background</h5>
<p id="P1">While the emergence of chronic and mucoid
<i>Pseudomonas aeruginosa</i> (
<i>Pa</i>) infection are both associated with poorer outcomes among CF patients, their
relationship
is poorly understood. We examined the longitudinal relationship of incident, chronic
and mucoid
<i>Pa</i> in a contemporary, young CF cohort in the current era of
<i>Pa</i> eradication therapy.
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<h5 class="section-title" id="d3281404e202">Methods</h5>
<p id="P2">This retrospective cohort was comprised of patients in the U.S. CF Foundation
Patient
Registry born 2006–2015, diagnosed before age 2, and with at least 3 respiratory cultures
annually. Incidence and age-specific prevalence of
<i>Pa</i> infection stages (initial and chronic [≥ 3
<i>Pa</i>+ cultures in prior year]) and of mucoid
<i>Pa</i> were summarized. Transition times and the interaction between
<i>Pa</i> stage and acquisition of mucoid
<i>Pa</i> were examined via Cox models.
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<h5 class="section-title" id="d3281404e222">Results</h5>
<p id="P3">Among the 5,592 CF patients in the cohort followed to a mean age of 5.5
years, 64%
(n=3,580) acquired
<i>Pa</i>. Of those, 13% (n=455) developed chronic
<i>Pa</i> and 17% (n=594) cultured mucoid
<i>Pa</i>. Among those with mucoid
<i>Pa</i>, 36% (211/594) had it on their first recorded
<i>Pa</i>+ culture, while mucoid
<i>Pa</i> emerged at or after entering the chronic stage in 12% (73/594). Mucoidy
was associated
with significantly increased risk of transition to chronic
<i>Pa</i> infection (HR=2.59, 95% CI 2.11, 3.19).
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<h5 class="section-title" id="d3281404e249">Conclusions</h5>
<p id="P4">Two-thirds of early-diagnosed young children with CF acquired
<i>Pa</i> during a median 5.6 years of follow up, among whom 13% developed chronic
<i>Pa</i> and 17% acquired mucoid
<i>Pa</i>. Contrary to our hypothesis, 87% of young children who developed mucoid
<i>Pa</i> did so before becoming chronically infected.
</p>
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