一种罕见的菌血症病原菌——霍氏鲍特菌的分离鉴定及临床意义分析

Identification and clinical significance of Bordetella holmesii isolated from a rare case of bacteremia in Nantong China

目的通过探讨一株罕见菌——霍氏鲍特菌(Bordetella holmesii, B.holmesii)的鉴定及耐药特征,分析其临床意义,提高对该菌的检出及临床诊疗水平。方法从细菌培养特性、生化特征以及16S rRNA基因序列分析来鉴定一株菌血症分离菌;运用Mega 7.0软件对鲍特菌属全部成员模式菌株与所分离菌16S rRNA基因序列进行同源性比对,并构建系统进化树;E-test法检测该分离菌的药物敏感性;分别添加不同浓度核黄素及其抑制剂光黄素于该菌培养基中,检测其生长活力。结果引起该免疫功能完善者菌血症的病原菌为B.holmesii,并将菌种上传中国普通微生物菌种保藏管理中心(CGMCC,菌种保藏号:CGMCC 1.13721);同时将该分离菌B.holmesii ABD2 16S rRNA基因序列上传美国国家生物技术信息中心(NCBI,序列号:KT828544.1);无根树显示B.holmesii与百日咳鲍特菌更具有亲缘性;药物敏感性试验(AST)显示哌拉西林、头孢他啶、头孢吡肟、亚胺培南、美罗培南、环丙沙星、左氧氟沙星、庆大霉素、阿米卡星、红霉素、四环素以及多黏菌素对该菌株的最小抑菌浓度(minimum inhibitory concentration,MIC)较低,而头孢唑啉、头孢呋辛酯、头孢西丁、头孢噻肟、氨曲南及复方新诺明的MIC值较高;核黄素能够促进B.holmesii的生长,光黄素则抑制该菌的生长。结论B.holmesii分离率极低,鉴定困难,因此临床、微生物学以及流行病学相关资料甚少,为一种罕见的病原菌,有待我们更深入地探讨。

Objective To analyze the identification, drug resistance and clinical significance of a rare bacterium of Bordetella holmesii(B.holmesii)to improve its detection and clinical diagnosis and treatment. Methods A strain isolated from a bacteremia case was identified by bacterial culture, biochemical tests and 16S rRNA gene sequencing. Mega 7.0 software was used to conduct a similarity analysis of 16S rRNA gene sequences between the type strains of Bordetella spp. and the isolate, and then a phylogenetic tree was constructed. Antibiotic resistance of the isolate was determined by E-test. Changes in bacterial growth were measured after adding different concentrations of riboflavin or its inhibitor lumiflavin to the culture medium. Results B. holmesii ABD2 was the pathogen causing bacteremia in the immunocompetent patient. It was deposited under the number of CGMCC 1.13721 in China General Microbiological Culture Collection Center(CGMCC), and the 16S rRNA gene sequences were deposited in National Center for Biotechnology Information(NCBI)with the accession number of KT828544.1. Unrooted tree showed that the B. holmesii strain was highly homologous with B. pertussis. Antibiotic susceptibility test showed that the minimum inhibitory concentrations(MIC)of piperacillin, ceftazidime, cefepime, imipenem, meropenem, ciprofloxacin, levofloxacin, gentamicin, amikacin, erythromycin, tetracycline and polymyxin B against the isolate were low, while the MIC values of cefazolin, cefuroxime, cefoxitin, cefotaxime, aztreonam and trimethoprim-sulfamethoxazole were high. Riboflavin accelerated the growth of B. holmesii ABD2, while its inhibitor lumiflavin had an inhibitory effect. Conclusions As B. holmesii is hard to isolate and identify, limited clinical, microbiological and epidemiological data are available. It is an under-recognized pathogen with a considerable amount of information that remains to be studied.