Chen Fei, Zhang Zhigang, Chen Jianzhong
Department of Pharmacy, Liaocheng People's Hospital, Liaocheng, China.
Medicine (Baltimore). 2018 Dec;97(50):e13658. doi: 10.1097/MD.0000000000013658.
Lactococcus lactis and Pediococcus pentosaceus are rare pathogens which rarely caused infections in humans. Several cases with L. lactis endocarditis have been reported in the literature, among them few were caused by L. lactis subsp. Lactis. Opportunistic P. pentosaceus infections were rarely reported.
A 66-year-old man presented to our hospital due to persistent fever for 15 days. A physical checking revealed a grade II holosystolic murmur at the heart apex. A chest computed tomography (CT) scan suggested bronchitis. L. lactis subsp. lactis was identified in blood cultures. Transthoracic and transesophageal echocardiography revealed the presence of a large hyperechogenic mass in the left atrium, and a large floating vegetation on the mitral valve with a severe mitral regurgitation.
Infectious endocarditis caused by L. lactis subsp. Lactis was diagnosed.
Levofloxacin (0.5 g/day) was used for 20 days; however, L. lactis subsp. lactis remained to be isolated from blood culture. Therefore, vancomycin (2 g/day) was used to replace levofloxacin. Six days after the treatment with vancomycin, the blood culture revealed no L. lactis subspecies lactis, but yielded a growth of gram-positive and non-spore forming cocci; and P. pentosaceus was identified. Antimicrobial susceptibility test revealed P. pentosaceus was sensitive to penicillin and levofloxacin. Vancomycin was discontinued, and levofloxacin (0.5 g/day) was restarted and treated for another 7 days. The patient recovered with negative blood culture results, and discharged from the hospital.
The patient recovered with negative blood culture results, and discharged from the hospital.
Our patient had a long-period of antibiotic treatment with strategy alterations. Standard interpretation criteria of Clinical and Laboratory Standards Institute (CLSI) for L. lactis should be established, and molecular tests will increase the identification rate of L. lactis infections.
乳酸乳球菌和戊糖片球菌是罕见的病原体，很少引起人类感染。文献中已报道了几例乳酸乳球菌性心内膜炎病例，其中少数由乳酸乳球菌乳酸亚种引起。机会性戊糖片球菌感染很少被报道。
一名66岁男性因持续发热15天前来我院就诊。体格检查发现心尖部有二级全收缩期杂音。胸部计算机断层扫描（CT）显示为支气管炎。血培养中鉴定出乳酸乳球菌乳酸亚种。经胸和经食管超声心动图显示左心房有一个大的高回声团块，二尖瓣上有一个大的漂浮赘生物，伴有严重的二尖瓣反流。
诊断为乳酸乳球菌乳酸亚种引起的感染性心内膜炎。
使用左氧氟沙星（0.5克/天）治疗20天；然而，血培养中仍可分离出乳酸乳球菌乳酸亚种。因此，使用万古霉素（2克/天）替代左氧氟沙星。使用万古霉素治疗6天后，血培养未发现乳酸乳球菌乳酸亚种，但培养出革兰氏阳性、无芽孢球菌；鉴定为戊糖片球菌。药敏试验显示戊糖片球菌对青霉素和左氧氟沙星敏感。停用万古霉素，重新开始使用左氧氟沙星（0.5克/天）并继续治疗7天。患者血培养结果转阴后康复出院。
患者血培养结果转阴后康复出院。
我们的患者接受了长时间的抗生素治疗并调整了治疗策略。应建立临床和实验室标准协会（CLSI）关于乳酸乳球菌的标准解读标准，分子检测将提高乳酸乳球菌感染的识别率。
