基质辅助激光解吸电离飞行时间质谱在鉴定儿童血流感染少见苍白杆菌的应用及耐药情况分析

Application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to identification of rare Ochrobactrum in children with bloodstream infection and analysis of the drug-resistance

目的快速鉴定和分析儿童血流感染少见苍白杆菌及其耐药情况分析。方法收集某儿童医院儿童血流感染的临床标本中分离的苍白杆菌26株,运用基质辅助激光解吸电离飞行时间质谱(matrix-assisted laser desorption/ionization time-of-flight mass spectrometry,MALDI-TOF MS)技术,对其进行检测,并结合测序结果分析确定菌株;根据药敏实验结果,用PCR法分析其耐药情况。结果26株实验菌株最后通过MALDI-TOF MS和16S rRNA基因测序技术,有25株被鉴定为解糖精假苍白杆菌,药敏结果显示它们对哌啦西林/他唑巴坦、喹诺酮类、氨基糖苷类和复方新诺明的耐药率为0.0%。而对氨曲南耐药率为100.0%,其他β-内酰胺类抗菌药物有不同的耐药率。AmpC和AmpR耐药基因检测均为阴性。结论MALDI-TOF MS能够快速鉴定临床少见苍白杆菌,儿童血流感染的解糖精假苍白杆菌不产头孢菌素酶,结合药敏分析结果及儿童用药特点,建议使用哌啦西林/他唑巴坦。

Objective To rapidly identify and analyze rare Ochrobactrum and its drug-resistance situation in children with bloodstream infection.Methods We collected 26 strains of Ochrobactrum isolated from clinical specimens from children with bloodstream infection in a children’s hospital.Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS)was used to detected the strains,and then they were identified based on biochemical phenotype and gene sequencing analysis.According to the results of drug susceptibility test,the drug-resistance genes were analyzed by PCR method.Results Among the 26 strains detected by MALDI-TOF MS and 16 S rRNA gene sequencing,25 strains were identified as Pseudochrobactrum saccharolyticum.Drug sensitivity results showed that their resistance rates to piperacillin/tazobactam,quinolones,aminoglycosides and cotrimoxazole were 0,but their resistance rate to amtriaxone was 100%.The otherβ-lactam antibacterial drugs had different drug-resistance rates.AmpC and AmpR gene tests were negative.Conclusion MALDI-TOF MS can rapidly identify clinical rare Ochrobactrum.The strains of Pseudochrobactrum saccharolyticum isolated from children with bloodstream infection do not contain AmpC or AmpR resistance genes.It is recommended to use piperacillin/tazobactam based on the results of drug sensitivity analysis combined with the characteristics of medication in children.