中台灣區域教學醫院之肺炎黴漿菌樣本的基因型探討

肺炎黴漿菌 (Mycoplasma pneumoniae) 是兒童及成人社區型肺炎的重要致病菌之一。巨環類抗生素（Macrolide）一直是治療兒童肺炎黴漿菌感染的首選用藥。對臨床分離株進行分子分型，有助於了解肺炎黴漿菌感染的流行病學，因此本研究乃針對中台灣臨床黴漿菌分離株探討其分子特徵與疾病症狀嚴重程度的相關性。本研究收集中部某區域教學醫院因呼吸道感染住院兒童（<14歲）喉頭檢體，共收集76個Ig M(+)的檢體，有29個肺炎黴漿菌培養陽性且Repmp1 PCR檢測陽性的分離株，針對此29臨床分離株利用P1基因型與Multiple-Locus Variable number tandem repeat Analysis (MLVA) 進行分子分型，並分析抗藥性與CARDS毒素的表現量。分離株的P1基因型主要為Type 1(28個；96.6%)，Type 2只有1個（3.4%）。而MLVA位點Mpn 13~16，其重複次數呈現4-5-7-2以及4-5-7-3二種基因型，比率約各佔一半，以Mpn 1位點再進一步分析，重複次數包括1、3、4、6，以重複3次與4次為主，其比率分別為55.2%及34.5%。巨環類抗生素抗藥性有5個(17.2%)，且只發生在4-5-7-2型，來自社區感染的黴漿菌，其巨環類抗生素抗藥性並無顯著增加。CARDS毒素表現量與Mpn 1基因型似乎較有相關性，高表現量只出現在少數型別，而流行率高的3、4型別CARDS毒素表現量都較低。臨床症狀的嚴重性似乎與分子型別無明顯相關性，然發燒時間較久的病例主要為4-5-7-3型。

Mycoplasma pneumoniae is one of the important pathogens of community pneumonia in children and adults. Macrolide antibiotics are the first choice for the treatment of Mycoplasma pneumoniae infections in children. Molecular typing of clinical isolates is helpful to understand the epidemiology of Mycoplasma pneumoniae infection. This study is to explore the molecular characteristics of clinical mycoplasma isolates from Taiwan. This study collected throat specimens of children (<14 years old) hospitalized due to respiratory tract infections. A total of 76 samples of IgM(+) were collected, of which 29 samples were positive for M. pneumoniae culture and Repmp1 PCR detection. We used P1 typing and Multiple-Locus Variable number tandem repeat Analysis (MLVA) for genotyping of 29 isolates. The macrolide susceptibility and CARDS toxin expression had also been detected. The P1 genotype of isolates is mainly type 1 (28/29; 96.6%) and only one isolate is type 2 (1/29; 3.4%). MLVA type of Mpn13~16 showed two genotypes, 4-5-7-2 and 4-5-7-3, and almost in equal proportions. The VNTR type of Mpn1 locus included 1, 3, 4, and 6, of which type 3 and 4 were predominant (55.2% and 34.5% respectively). There are 5 isolates showed macrolide resistance (17.2%), and all are MLVA type 4-5-7-2. The macrolide resistance incidence of M. pneumonia infection acquired from community did not increase significantly. The expression level of CARDS toxin seems to be correlated with Mpn 1 genotype, high toxin expression were only found in low prevalence types, while the high prevalence types (type 3 and 4) have low toxin expression. The severity of clinical symptoms has no obvious correlation with molecular type, but the cases with longer fever are mainly type 4-5-7-3.