Efficacy and outcomes associated with carbapenem treatment during a resistant Shigellosis cluster in Portland
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Publication Date
2025
Abstract
Abstract: Shigella has caused multiple diarrheal illness outbreaks across the Portland metro area over the past decade. These infections have become both more numerous and difficult to treat with an increasing proportion of extensively drug resistant (XDR) strains. Consequently, hospitals within our health system have utilized short courses of carbapenems for patients with severe symptoms. This project is designed to compare clinical outcomes of patients treated with carbapenems to those treated with traditional first-line antibiotics or supportive care. Additionally, we aimed to better characterize the risk factors and prevalence of XDR shigellosis within our health system. This was a multi-center retrospective cohort study across five Providence hospitals within the Portland-metro area that was approved by the Institutional Review Board. All patients aged 18 years or older and diagnosed with Shigellosis from October 2023 to August 2024 were screened for inclusion. Patients who tested positive for Clostridium difficile or had a positive gastrointestinal (GI) multiplex result with an organism other than Shigella were excluded. The two comparator groups were those treated with carbapenems versus those treated with alternative antibiotics or supportive care alone. The primary outcome was number of days until resolution of symptoms as defined by less than 3 recorded stool occurrences in one day. Patients started on antibiotics after their documented resolution of symptoms or seen only in the emergency department were not included in the final analysis. Other data points collected included patient characteristics such as age, sex, race/ethnicity, housing status, HIV status, presence of comorbid GI disease, fever status, white blood cell count (WBC), and mean arterial pressure (MAP). For data analysis, a student T-test was used to assess the primary outcome. Sixty-four patients met inclusion criteria. Twenty-nine (45%) were treated with carbapenems, while 35 (55%) were treated with non-carbapenem antibiotics or supportive care only. Mean time to resolution of symptoms was not significantly different in the carbapenem versus non-carbapenem group (42.7 vs 30.6 hours, p = 0.41). Patients treated with car-bapenems had longer lengths of hospital stay (167.5 vs 78.7 hours) compared to patients treated with non-carbapenem antibiotics. WBC, temperature, and MAP on presentation were similar between groups. Antibiotic susceptibilities were performed on 12 (19%) samples; 1/11 (9.1%) were resistant to ceftriaxone, 3/12 (25%) were resistant to ciprofloxacin. Treating shigella infections with carbapenems was associated with longer resolution of symptoms when com-pared with non-carbapenem antibiotics, despite similar infectious markers at time of presentation between the two groups. Learning objectives: Assess the effectiveness of using carbapenems as first-line therapy in treating XDR shigellosis. Describe clinical characteristics of Shigella infections within the Portland-metro area. Presentation Category: Infectious Diseases
Specialty/Research Institute
Graduate Medical Education
