- 期刊
食品工廠檢測仙人掌桿菌及金黃色葡萄球菌之能力評估
Competency Assessment on Bacillus cereus and Staphylococcus aureus Enumerations of Food Manufactories in Taiwan
摘要
仙人掌桿菌(Bacillus cereus)和金黃色葡萄球菌(Staphylococcus aureus)是常見的食品中毒菌，本文針對國內食品工廠的品管實驗室，以能力試驗(proficiency test, PTest)評估其對這兩種病原菌典型菌落判定計數的檢測程序合適性。以選擇性培養基，進行仙人掌桿菌BA與BB兩個樣品及金黃色葡萄球菌SA、SB與SC三個樣品的檢測。仙人掌桿菌的檢測結果，其實驗室內的檢測結果差異(|Zwi|)在1.76以下，由於BA與BB兩樣品實為相同的樣品，顯示實驗室的重複性檢測結果為合適。但由各廠商間的檢測結果差異(Zbi)，發現廠商編號M11的檢測結果偏離標準，其Zbi為－5.99，由尤頓圖得知，該廠商的檢測程序出現系統性的誤差。對金黃色葡萄球菌檢測PTest結果，發現廠商編號M17的廠商間檢測結果差異(Zbi)偏離標準，其Zbi為－3.69，尤頓圖亦顯示該廠商的檢測結果出現系統性的誤差。經檢測程序分析，發現兩家廠商均於培養24小時後即判讀典型菌落計數菌數，但典型菌落特徵需培養48小時才可完全顯現，因而造成低估菌數的現象。由能力試驗評估顯示95%參與試驗的實驗室的自主檢測能力良好，但是對於仙人掌桿菌和金黃色葡萄球菌各有一家工廠因培養計數時間未達48小時，造成低估菌數的現象，經能力試驗分析後，已更正其檢測的程序。
並列摘要
Food Industry Research and Development Institute (Accepted for publication: September 24, 2010) Bacillus cereus (B. cereus) and Staphylococcus aureus (S. aureus) are both common food poisoning bacteria; hence this research looks into the procedures of how domestic food manufactories enumerate the typical colony counts of these two pathogenic bacteria. The proficiency test (PTest) was used to collect data on the accuracy of the manufactories' detection procedures with the selective culture media. The food manufacturers which participated in the research were asked to perform tests on two B. cereus samples, BA and BB, and three S. aureus samples, SA, SB and SC. For both BA and BB, laboratory results via the PTest showed a within lab Z score (|Zwi|) of less than 1.76. Since BA and BB actually were the same samples, it indicated the appropriateness of the laboratory's recurrent test results. However, the manufacturers' between lab Z score (Zbi) showed manufacturer No. M11 exhibiting a deviation from the standard, with a -5.99 Zbi value. According to the Youden Plot, systematic errors occurred in that particular manufacturer’s testing results. For Staphylococcus aureus, the testing results showed that results from manufacturer No. M17 exhibited a -3.69 Zbi value. The Youden Plot also illustrated systematic errors occurred during the testing process for manufacturer No. M17. After thorough analysis, it was concluded that incubation time was the reason why the two manufacturers exhibited an underestimate result. Both conducted the discriminative readings on the typical bacterial colonies for counting bacterial populations after 24 hours incubation. However, the typical bacterial colony characteristics would not be fully exhibited until being cultured for 48 hours. The competency assessment indicated that 95% of the food manufacturers participating in the research exhibited an outstanding voluntary testing competency. As for the two manufacturers which underestimated the bacterial population by not extending the culture and counting time, their testing procedures were corrected after discussion.