嗜碳性imipenem-resistant Proteus mirabilis實驗室表現型之研究

Laboratory Characterization of A Capnophilic Imipenem-resistant Proteus mirabilis Isolate

在2014年，在南台灣的某區域醫院，分離出一株嗜碳性imipenem-resistant Proteus mirabilis，因為菌株少見，因此我們研究這菌株的實驗室表現。經四種細菌鑑定方法含傳統生化八管試驗鑑定、Phoenix自動化偵測儀、API 20E套組鑑定及基質輔助雷射脫附電離──飛行時間式質譜儀，皆鑑定為P. mirabilis。此菌經血液培養基培養，無法生長於一般溫箱，只能在有CO_2濃度的環境中生長，並於5%及7.5% CO_2濃度生長最好。此菌對大部分的抗生素（包括第三代cephalosporin 、piperacillin-tazobactam及imipenem）都不具敏感性，只對ertapenem、meropenem及doripenem具敏感性。在此，我們提出二個建議，第一，如果細菌只能生長於有CO_2濃度的培養箱，而在一般溫箱無法生長，需注意此菌株是否為嗜碳性細菌。第二，若傳統生化鑑定方法或自動化儀器可鑑定出腸桿菌科細菌，但卻無法得到抗生素敏感性試驗的結果，需注意此菌株是否為嗜碳性腸桿菌科細菌。

A capnophilic imipenem-resistant Proteus mirabilis strain was isolated in 2014 at a regional hospital in southern Taiwan. This isolate was subsequently identified as a rare P. mirabilis strain by all four bacterial identification methods, including traditional biochemistry identification, Phoenix automachine, API 20E, and matrix-assisted laser desorption ionization-time of flight mass spectrometry. The isolate failed to grow on sheep blood agar incubated in the ambient air, but could grow well in the 5% and 7.5% CO_2 environment. The isolate was nonsusceptible to most antibiotics tested, including third-generation cephalosporins, piperacillin-tazobactam, and imipenem, and only susceptible to ertapenem, meropenem, and doripenem. Herein, we bring up two suggestions. First, if organisms can grow in the CO_2 incubator, but fail to grow in the ambient air environment, capnophilic organisms should be highly suspected. Second, while the isolate was identified as Enterobacteriaceae using traditional biochmistry identification method or automation systems, but failed in antimicrobial susceptibility tests, capnophilic Enterobactericeae should be highly suspected.