外科加護病房多重抗藥性鮑氏不動桿菌群聚移生及感染之調查與處理

Investigation and Management of a Cluster of Colonizations/Infections Associated with Multidrug-resistant Acinetobacter baumannii at a Surgical Intensive Care Unit

某醫學中心一個12床的外科加護病房，於2007年9月11日至10月9日之間發生多重抗藥性鮑氏不動桿菌 （multidrug-resistant Acinetobacterbaumannii; MDRAB） 造成的移生／感染群聚現象。本小組人員經由例行性院內感染監測發現此情形，立即與病房感控專責醫師及單位主管聯絡，進行現場觀察，加強洗手與落實接觸隔離措施及成組照護，並立即以 5,000 ppm 漂白水加強環境消毒，並連續執行共4週。經由個案分析及流行病學調查發現，共有6位病患分別自痰液、中心靜脈導管、血流等部位檢體培養出 MDRAB，全部個案過去皆使用過廣效性抗生素，尤其是第三代頭芽孢子素，並接受呼吸器等侵入性治療。為了釐清可能的傳播途徑及找出可能感染源，便進行環境採樣培養共109件檢體，以及人員手部培養共12件檢體。結果顯示，清潔區、病人區、以及現場工作人員手上，均可檢出 A. baumannii （分別為0件、3件、及5件）或 MDRAB （分別為1件、8件、及1件） ，且其中14株與移生病人的 MDRAB 菌株之基因型相同。為釐清當時其他7位仍住在該單位內之非 MDRAB 帶菌現象，遂分別進行痰液、尿液及糞便篩檢。3件痰液培養 MDRAB 均為陰性；經由感染管制措施的再加強，並持續監督其落實情形，此一群聚終於獲得有效控制。自以上環境監測推估，環境中 MDRAB 的污染，再藉由工作人員的手，在病人與環境問散播，可能是造成此次群聚的主要原因。（感控雜誌 2009; 19: 146-59）。

From September 11 through October 9. 2007, a cluster of colonizations/infections associated with multidrug-resistant Acinetobacter baumannii (MDRAB) was identified and investigated at a 12-bedded surgical intensive care unit (ICU) of a medical center. This event was identified by infection control personnel through routine surveillance and the ICU staffs were informed immediately. After the on-site observation, hand hygiene and contact precaution were reinforced and the colonized/infected patients were cohorted. The environment was disinfected with 5,000 ppm hypochlorite solution immediately and once a week for the next 3 weeks. Reviewing of the medical records revealed that MDRAB was discovered from the sputum, central venous catheter. and blood samples of 6 patients. All patients received broad-spectrum antimicrobial therapy and intubation for ventilatory support before this event. To elucidate the mode of transmission and source of colonization/infection, microbial surveillance of the environment and hospital staffs were undertaken. Among 109 swab cultures collected from ICU environment and hands of 12 healthcare workers, MDRAB was identified from clean area (1 isolate), patient area (n=8), and hand cultures (n=1). Isolates of A. baumannii other than MDRAB were identified from patient area (n=3) and hand cultures (n=5) The genotypes of 14 surveillance isolates were identical to that of MDRAB isolates from patients. During the investigation, vancomycin-resistant Enterococcus faecium (VRE) were also isolated from the clean area ( 4 isolates), patient area (n=12), and hand cultures (n=2). An identical genotype was found of 12 VRE isolates. To reveal the other cryptic MDRAB or VRE cases, active microbial surveillance of 7 other patients who resided at the ICU was conducted. None of the sputum specimens was found to have MDRAB, while VRE were discovered from 2 stool specimens. After infection control measures were reinforced and compliance was monitored, the cluster was under control. This study showed that contamination of the environment and the further spread through the hands of hospital staff contributed to the cross transmission of MDRAB among patients occurred. Furthermore, a concomitant VRE outbreak was not noted until the active microbial surveillance was conducted. (Infect Control J 2009; 19:146-59).