Kozakai Moe, Matsumoto Mami, Matsumoto Chieko, Uchida Shigeharu, Nagai Tadashi, Satake Masahiro, Tadokoro Kenji
Central Blood Institute, Blood Service Headquarters, Japanese Red Cross Society and Kanto-Koshinetsu Block Blood Center, Japanese Red Cross Society, Tokyo, Japan..
Central Blood Institute, Blood Service Headquarters, Japanese Red Cross Society and Kanto-Koshinetsu Block Blood Center, Japanese Red Cross Society, Tokyo, Japan.
Transfusion. 2016 Oct;56(10):2602-2606. doi: 10.1111/trf.13752. Epub 2016 Aug 4.
Bacterial contamination of platelet concentrates (PCs) remains a serious problem in transfusion. We have been conducting sterility tests on all PCs rejected by blood centers or hospitals due to abnormal appearances. We recently experienced a case in which discrepant results were obtained between the methods used to identify a bacterial species isolated from a PC, requiring further analyses.
Bacteria were isolated from a PC using the BacT/ALERT system and plate culture. The species was identified using biochemical tests and molecular analysis. Phylogenetic trees were constructed using sequences of the 16S ribosomal RNA (rRNA) and superoxide dismutase (sodA) genes from the bacterial isolate and related species. In addition, the isolate was cultured at temperatures of 10°C and below to determine its growth activity at low temperatures.
Biochemical tests determined that the isolate was Streptococcus alactolyticus, whereas molecular analysis determined that it was Lactococcus garvieae. These two species belonged to different clusters on the phylogenetic tree. Similar to L. garvieae, the isolate could grow at 10°C.
We conclude that the isolate was L. garvieae according to molecular identification and its growth characteristic at 10°C. Molecular analysis enabled the identification of this species, which was difficult to classify by biochemical tests. Blood facilities need to be prepared with multiple techniques, including genetic analysis techniques, for identifying contaminating bacterial species. L. garvieae can grow at 10°C and can contaminate both red blood cell concentrates and PCs; thus, this species should be listed as a cryophilic bacterium that could threaten blood safety.
血小板浓缩物（PCs）的细菌污染仍然是输血领域的一个严重问题。我们一直在对因外观异常而被血站或医院拒收的所有PCs进行无菌检测。最近我们遇到了一个案例，从一份PCs中分离出的细菌物种，其鉴定方法之间得到了不一致的结果，需要进一步分析。
使用BacT/ALERT系统和平板培养从一份PCs中分离细菌。通过生化试验和分子分析鉴定该物种。使用细菌分离株及相关物种的16S核糖体RNA（rRNA）和超氧化物歧化酶（sodA）基因序列构建系统发育树。此外，将分离株在10°C及以下温度培养，以确定其在低温下的生长活性。
生化试验确定分离株为非解乳糖链球菌，而分子分析确定其为格氏乳球菌。这两个物种在系统发育树上属于不同的簇。与格氏乳球菌相似，该分离株能在10°C生长。
根据分子鉴定及其在10°C的生长特性，我们得出该分离株为格氏乳球菌的结论。分子分析能够鉴定出这种通过生化试验难以分类的物种。血液机构需要准备多种技术，包括基因分析技术，用于鉴定污染的细菌物种。格氏乳球菌能在10°C生长，可污染红细胞浓缩物和PCs；因此，该物种应被列为可能威胁血液安全的嗜冷菌。
