肺炎鏈球菌(Streptococcus pneumoniae)火山口樣菌落特徵的影響因素

Factors Affecting the Volcano-Shaped Colonial Morphology of Streptococcus pneumoniae

黃軒旻(Hsuan-Min Huang) ； 蔡偉勳(Wei-Shiun Tsai) ； 蔡文城(Wen-Cherng Tsai)

《檢驗及品保雜誌》 4卷3期 (2015/08) Pp. 108-113

https://doi.org/10.6573/JTQA.201508_4(3).02

摘要

菌落特徵為傳統微生物鑑定方法的依據之一，由於近年來matrix-assisted laser desorption ionizationtime-of-flight mass spectrometry (MALDI-TOF MS)漸漸被用於微生物的鑑定，雖然最初購買儀器成本及維護費高，但鑑定速度快、試劑成本低而廣泛地被檢驗室所接受，然而此儀器對鏈球菌的鑑定仍有其缺陷，尤其是不能區分肺炎鏈球菌（Streptococcus pneumoniae）及相近的草綠色鏈球菌(viridans group streptococci)，因此肺炎鏈球菌菌落特徵的觀察，在此菌的鑑定上更顯得重要。肺炎鏈球菌在含綿羊血的血平板(blood agarplate, BAP)生長時菌落呈型溶血(不完全溶血)，即菌落周圍呈草綠色溶血圈，尤其是衰老時，菌落會出現火山口或臍狀凹陷，此特性成為鑑別此菌的一個重要依據。為了瞭解菌落凹陷的影響因素，吾等以不同的培養基類別、培養基乾燥程度、培養環境、不同廠牌BAP及菌株進行評估，結果發現這些參數均可能影響菌落的凹陷觀察。基於上述的發現，吾等建議檢驗室採用MALDI-TOF MS 鑑定肺炎鏈球菌時，應先熟悉此菌菌落特徵的各種影響因素，然後才能根據菌落凹陷特徵，並配合其它傳統的生化試驗快速且正確地鑑定出此菌。

關鍵字

肺炎鏈球菌 ； 血平板 ； 火山口或臍狀凹陷 ； 影響因素

並列摘要

The colonial characteristic is one of the criteria used in the conventional microbial identification method. Recently, matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) has become commonly used in clinical laboratories to replace the conventional methods. Although MALDITOF MS entails high costs in terms of both instrumentation and maintenance, its short turnaround time for microbial identification and low cost for reagents have made it popular among resourcerich laboratories. However, MALDI-TOF MS is not ideal for some types of microbial identification, especially for differentiating between Streptococcus pneumoniae and the viridans group of streptococci. As such, the observation of colonial morphology in S. pneumoniae has become important. Mature colonies of S. pneumoniae grown in BAP (blood agar plate) with defibrinated sheep blood will be alphahemolytic (exhibiting incomplete hemolysis of the blood), i.e., there will be a green color around the colonies, which will exhibit a volcanoor umbilical shape as they age. This characteristic, coupled with optochin susceptibility and/or bile solubility, is used as the criteria for the conventional identification of S. pneumoniae. To understand the factors affecting the formation of a volcanoshaped colony, we used different brands and kinds of media, clinical strains and incubation conditions to investigate such formation and found that all of the above-mentioned parameters can affect the formation of volcano-shaped colonies. Based on the above findings, we recommend that laboratory personnel should be familiar with the factors affecting the formation of volcano-shaped colonies of S. pneumoniae when using MALDI-TOF MS for the routine identification of S. pneumoniae.

並列關鍵字

Streptococcus pneumonia ； blood agar plate ； factors affecting volcano-shaped colonies