中部某區域醫院住院病人Methicillin抗藥性金黃色葡萄球菌鼻腔帶菌之現況調查

Nasal Methicillin-resistant Staphylococcus aureus Carriage among Hospitalized Patients in a Regional Hospital: One Time Point Prevalence, Molecular Characteristics, and Risk Factors

Methicillin抗藥性金黃色葡萄球菌（Methicillin-resistant Staphylococcus aureus，MRSA）近十年來不只在醫院間醫療照護相關MRSA（Healthcare associated MRSA，HA-MRSA）感染漸趨嚴重，社區型MRSA（Communityassociated MRSA，CA-MRSA）感染率亦增加，研究發現HA-MRSA及CAMRSA之分子生物學特徵不甚相同，但皆可能引起皮膚、傷口、肺炎、菌血症及心包膜炎等感染。本研究時間為2012年5月18日至22日，針對全院住院病患共502人，以無菌鼻腔拭子取得檢體進行細菌培養，結果發現鼻腔帶菌之金黃色葡萄球菌比率為12.15％，其中MRSA比率為6.17％，再以PFGE型態表現進行鑑定型別共5型，分別為Type A（19.35％）;Type C（35.48％）;Type D（19.35％）;Type F（9.68％）;Type BM（16.13％）。大多數MRSA屬於sequence type（ST）59及ST 239，ST 59為CA-MRSA菌株；ST 239為HA-MRSA菌株。以chi-square檢定並以logistic regression model 進行多變項分析，結果顯示年齡0～18歲MRSA鼻腔帶菌比率最高，佔11.8％，顯著性地高於30歲以上的族群，顯示MRSA帶菌比率與年齡有相關。針對潛在疾病及相關影響因素進行危險因子分析（包括抗生素、侵入性管路、是否曾感染MRSA、慢性疾病、住院史……等），結果顯示在MRSA帶菌比率和危險因子之間並無統計相關（p=0.964）。31株MRSA中，有4株為台灣常見的HA-MRSA菌株，分別是1株PFGE A／ST 239／SCCmec IIIA及3株PFGE F／ST 5／SCCmec II；有17株為台灣常見的CA-MRSA菌株，分別是11株PFGE C／ST 59／SCCmec IV及6株PFGE D／ST 59／SCCmec IV or VT等分型；其餘3株ST 508與7株為ST 45同屬基因群45（clonal complex 45），為台灣地區近幾年新出現的菌株，值得我們進一步觀察及研究。 Methicillin-resistant Staphylococcus aureus (MRSA) is the primary pathogen that caused infections over the last decade. The infections were increasingly serious not only in healthcare-associated (HA-MRSA) but also in communityassociated MRSA (CA-MRSA). Both HA-MRSA and CA-MRSA were likely to cause infections, such as in the skin, wounds, pneumonia, bacteremia, and endocarditis. Studies have revealed that their molecular biological characteristics were substantially different. A cross-sectional study conducted during May 18- 22, 2012, collected 502 samples with nasal swab among hospitalized patients in a regional hospital. The carriage rate of S. aureus and MRSA was 12.15% and 6.17%, respectively. The five MRSA isolates showed different molecular profiles in pulsedfield gel electrophoresis: type A, 19.35%; type C, 35.48%; type D, 19.35%; type F, 9.68%; and type BM, 16.13%. Most of the MRSA isolates were sequence type (ST) 59 and ST 239. ST 59 is part of CA-MRSA and ST 239 is part of HA-MRSA. Statistical analysis was performed using the chi-square test and multivariate logistic regression. The results showed that the highest rate of MRSA nasal colonization developed at age 0-18 years old (11.8%), which showed the correlation between MRSA carriage rate and age. No significant differences were observed between MRSA carriage rate and risk factors such as antibiotic usage, catheter intubation, previous clinical MRSA isolates, chronic diseases, and previous hospitalization (p = 0.964). In addition, four of the 31 MRSAs were the common HA-MRSA in Taiwan, which included PFGE A/ST 239/SCCmec IIIA and PFGE F/ST 5/SCCmec II. The last ST 508 and ST 45 were newly emerging isolates in the recent years in Taiwan, which belong to the same gene group. The conclusion should be confirmed with further observation and research.