後疫情時代南台灣某區域教學醫院OXA-181產酶Citrobacter koseri之流行病學分析

Epidemiological Analysis of OXA-181–Producing Citrobacter koseri in a Regional Teaching Hospital in Southern Taiwan in the Post-Pandemic Era

本研究回溯性分析台灣南部某區域教學醫院2018至2024年間所共計分離之52株blaOXA-181陽性carbapenem-resistant Citrobacter koseri（CRCK）臨床菌株，探討其流行趨勢、抗藥性特徵與院內分布情形（原86株CRCK，其中84株（97.7%）帶有blaOXA-181基因；經排除重複分離菌株後，最終納入52株進行後續分析）。自2023年COVID-19後期起，該菌株檢出數量明顯上升（至2022年的三株到2023年的19株），主要來自痰液（n = 34，65.4%）與尿液檢體（n = 15，28.8%），且多數個案為長期照護機構轉介病人（n = 39，75.0%）。菌株分布亦多見於3A病房（n = 17且88.2%為院內感染；多集中於2024年的5月及8月）及5A病房（n = 9且77.8%為院內感染）的特定病區域，呈現時間與空間之聚集與擴散趨勢。藥物敏感性分析顯示菌株對多數常用抗生素皆具抗藥性，僅對flomoxef保有敏感性，tigecycline則表現出明顯異質性（31株為susceptible；21株為non-susceptible）。分析該菌株具高度抗藥性，長期移生（colonization），與傳播潛力。抗藥性菌株之篩選可能與COVID-19疫情解封之感控措施相關，並可能透過照護流程於院內擴散，建議未來除落實感染控制措施外，亦應導入人工智慧輔助之即時監測與預警系統，以強化群聚事件偵測與防疫介入效能。

This retrospective study analyzed 52 clinical isolates of blaOXA-181–producing carbapenem-resistant Citrobacter koseri (CRCK) collected at a regional teaching hospital in southern Taiwan between 2018 and 2024, with the aim of characterizing temporal trends, antimicrobial resistance profiles, and in-hospital distribution patterns. Among the 86 initially identified CRCK isolates, 84 (97.7%) were positive for blaOXA-181. After excluding duplicate isolates, 52 non-duplicate isolates were included in further analyses. Since the late phase of the COVID-19 pandemic in 2023, the number of detected isolates increased markedly, from 3 isolates in 2022 to 19 isolates in 2023. Most isolates were recovered from sputum (n = 34, 65.4%) and urine specimens (n = 15, 28.8%), and the majority of cases involved patients referred from long-term care facilities (n = 39, 75.0%). Isolates were disproportionately clustered in specific wards, particularly Ward 3A (n = 17, 88.2% classified as hospital-acquired infections; largely concentrated in May and August 2024) and Ward 5A (n = 9, 77.8% hospital-acquired), suggesting spatiotemporal clustering with subsequent dissemination. Antimicrobial susceptibility testing showed resistance to the most commonly used agents; susceptibility was preserved only to flomoxef, whereas tigecycline exhibited pronounced heterogeneity (31 susceptible vs. 21 non- susceptible isolates). Collectively, these findings indicate that OXA-181–producing CRCK has a high level of multidrug resistance, with substantial potential for persistent colonization and transmission. The observed emergence may be associated with changes in infection prevention and control practices following COVID-19 reopening, with possible in-hospital spread through care-related workflows. In addition to strengthening conventional infection control measures, we suggest implementing AI-assisted real-time surveillance and early-warning systems to enhance cluster detection and improve the timeliness and effectiveness of outbreak interventions.