Chest Infections |

Clinical Implications of Group A Streptoccoccus (GAS) Infections in Adults With Cystic Fibrosis (CF) FREE TO VIEW

Kate Skolnik, MD; Ranjani Somayaji, MD; Harvey Rabin, MD; Michael Parkins, MD; Austen Nguyen
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University of Calgary, Department of Medicine, Division of Infectious Disease, Calgary, AB, Canada

Chest. 2015;148(4_MeetingAbstracts):122A. doi:10.1378/chest.2254424
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SESSION TITLE: Chest Infections Posters I

SESSION TYPE: Original Investigation Poster

PRESENTED ON: Wednesday, October 28, 2015 at 01:30 PM - 02:30 PM

PURPOSE: To determine the incidence, natural history, and clinical impact of GAS infections in adults with cystic fibrosis (CF).

METHODS: We retrospectively evaluated the Calgary Adult CF Clinic biobank (a repository of frozen bacterial isolates from all CF sputum samples submitted since 1978). Patients with at least one GAS isolate were included. We recorded patient demographic information, spirometry, co-infections, and the number and management of pulmonary exacerbations (PEx). The primary outcome was the PEx occurrence at incident culture (defined as the 2 weeks preceding and 4 weeks following collection). A PEx was defined based on Fuchs criteria. A severe PEx was one requiring intravenous antibiotics or hospitalization. Secondary outcomes included: PEx frequency in individuals before and after the first GAS isolate, change in % predicted forced expiratory volume in one second (FEV1) at the time of the GAS versus the last clinic visit, complications of GAS infection, and rate of progression to chronic infection.

RESULTS: Fifteen individuals who cultured GAS 20 times were identified. At the time of GAS isolation, 47 % (7/15) of subjects experienced a PEx and half of these (4/7) were severe. Of the GAS isolates, 45% (9/20) were associated with a PEx; just under half (4/9) were severe. Patients were more likely to have an exacerbation at the time of the index GAS isolate compared to the preceding visit, however the difference was not statistically significant (RR 6, 95% CI 0.82-43.0, p= 0.08). Most patients (9/15) had a lower PEx frequency after the first GAS isolate compared to the two preceding years. Although only 33% (5/15) had a higher PEx frequency after the index isolate, all of them experienced a greater frequency of severe PEx. Few individuals (2/13 or 15.4%) had a drop in FEV1 (10% or more) at the time of GAS isolation. Bacteremia, necrotizing pneumonia, and empyema were not observed. One subject developed prolonged GAS colonization (cultures positive for 6 months), which ultimately cleared spontaneously.

CONCLUSIONS: GAS was an uncommon lower respiratory pathogen in our adult CF population. GAS in sputum was often associated with PEx. However, this did not result in either chronic infection or an appreciable change in disease trajectory.

CLINICAL IMPLICATIONS: In our population, GAS increased the risk of PEx. Clinicians may consider antibiotic treatment for CF patients with a new GAS sputum isolate to mitigate this risk.

DISCLOSURE: The following authors have nothing to disclose: Kate Skolnik, Ranjani Somayaji, Harvey Rabin, Michael Parkins, Austen Nguyen

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