矯正單位和醫院間抗甲氧苯青黴素金黃色葡萄球菌在皮膚與軟組織感染之分子流行病學比較分析

Comparison of Molecular Epidemiology, Mupirocin and Chlorhexidine Resistance of Methicillin- Resistant Staphylococcus aureus Associated Skin and Soft Tissue Infections Between Custodial Facilities and A Community Hospital in Taiwan

研究目的:抗甲氧苯青黴素金黃色葡萄球菌(methicillin-resistant Staphylococcus aureus, MRSA)是臨床感染症最常見的病菌之一。為了瞭解彰化矯正單位與醫院菌株的流行病學資料,本研究分析來自彰化矯正單位與彰濱秀傳醫院從皮膚與軟組織感 染(skin and soft tissue infections, SSTIs)所分離 MRSA 菌株,透過多種分子鑑定分析、綜合探討 MRSA 在醫院與矯正單位菌株分佈特性與差異。

檢體來源與方法:本研究檢體來源均是由皮膚軟組織感染所分離的 MRSA 菌株,包括 彰濱秀傳醫院所凍存的 134 個菌株以及來自矯正單位的 219 個 MRSA 菌株 , 總共 353 株。除了針對臨床 12 種抗生素抗藥性分析外,也運用分子技術進行葡萄 球菌卡莢基因型分析(Staphylococcal cassette chromosome mec, SCCmec)、多位點序列分型法(Multi-Locus Sequence Typing, MLST)、mupA 及 qacA/B 抗藥基因 分析,綜合探討皮膚分離之 MRSA 感染菌株在不同區域間之分子流行病學。

實驗結果：在這353 株MRSA 菌株中，SCCmec 基因分型分佈比例為SCCmec IV （58.4%），SCCmec VT（31.7%），以及SCCmec V（7.4%）。MLST 序列分型（ST）型別為ST59（36.4%），ST8（35.2%），ST45（17.9%）。MRSA 在矯正 單位的分離率（78.2%）較醫院高（17.3%），有顯著的差異（p<0.001）。矯正單位的MRSA 菌株主要是攜帶SCCmec IV（65.3%）；ST 型別分佈主要以ST8 為主（38.4%）。研究發現ST45 的分佈在矯正單位（23.2%）與醫院（9.7%）間有顯 著差異（p=0.019）。所有MRSA 菌株攜帶mupA 抗藥基因的比率為91.5%，其中矯正單位有高達95.4% 的攜帶率。此外，在所有MRSA 菌株攜帶qacA/B 抗藥 基因的比率為25.8%，醫院的攜帶率為55.2% 與矯正單位間（7.8%）有顯著的差異（p<0.001）。

結論：此次研究結果在皮膚軟組織感染的MRSA 型別主要是ST59、ST8 及ST45，但 矯正單位與醫院間感染的MRSA 型別分佈有明顯不同。在矯正單位與醫院間從皮膚所分離的菌株攜帶mupA 的抗藥基因都大於80% 以上，反之qacA/B 抗藥基 因多存在於醫院菌株，矯正單位則攜帶率為（7.8%）。為避免MRSA 的群聚感染與去移生治療失敗，在用藥上必須考慮mupA 基因高攜帶率的部分。目前臨床 治療MRSA 有著高度的抗藥性，而文獻指出Doxycycline 口服藥物對此菌株治療的敏感性較佳，可作為治療的首選藥物之一。

 

Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) is a common and major pathogen responsible for skin and soft tissue infections (SSTIs). This study was aimed to delineate the molecular genotype distribution and antibiotic resistance genes amongst MRSA isolates from three corrections agencies in Changhua (including one prison, one jail and one rehabilitation unit) and Chang Bing Show-Chwan Memorial Hospital.

Methods: A total of 353 clinical MRSA isolates derived from custodial facilities and Chang Bing Show-Chwan Memorial Hospital in Changhua throughout the 2017 calendar year were investigated by using molecular genotyping, multi-locus sequence typing (MLST) and PCR detection for mupirocin and chlorhexidine resistance genes.

Results: Of 353 MRSA isolates, the top three leading SCCmec types in order were SCCmec IV (58.3%), SCCmec VT (28.3%), and SCCmec V (7.3%). For sequence type, ST59 was the leading type and accounted for 36.4%, followed by ST8 (35.2%) and ST45 (17.9%). With respect to MRSA derived from custodial facilities, MRSA was responsible for 78.2% of SSTI, which is significantly higher than the rate in the hospital (p <0.001). MRSA from custody predominantly carried SCCmec type IV (65.3%) and had a distribution pattern of a distinct sequence type: ST8 was the leading sequence type (38.4%), and of note, the rate of ST45 was significantly higher in comparison to the hospital (23.2% vs 9.7%, p=0.019.). For mupirocin and chlorhexidine resistance, most MRSA carried high resistant mupA genes (91.4%) but the overall qacA/B gene carriage rate was only 25.8%. By contrast, MRSA from custody had a lower rate of qacA/B gene carriage (7.8% vs 55.2%, p<0.001).

Conclusions: ST59, ST8 and ST45 MRSA are the leading circulating MRSA strains in Taiwan but the molecular distribution varied distinctly between the custodial facilities and hospital. Mupirocin resistance rate is quite high regardless of the origin of MRSA. Chlorhexidine resistance is relatively low, especially seen in MRSA from custodial facilities, and could potentially be used for custodial environmental decolonization.