关键词: 沙门菌, 16S rRNA基因测序, 基质辅助激光解析电离飞行时间质谱, 耐药, blaCTX-M

Abstract: Objective To investigate the rapid identification and the antimicrobial resistance characteristics of Salmonella recovered from children. Methods Selected 75 strains Salmonella which were isolated from children. Via standard biochemical and serological tests for all strains were identified. 16S rRNA sequencing method was used to identify. Matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) method was used to identify. The results of the above two methods with traditional culture methods were compared and analyzed. Kerby-Bauer disk diffusion method for commonly used antibiotic sensitivity test was used. Polymerase chain reaction (PCR) method was used to analyze extended-sptectrum beta-lactam resistant gene. Results Seventy-five Salmonella, Salmonella Typhimurium and Salmonella enteritidis were the predominant serotypes, respectively 32 and 26. The results of 16S rRNA gene sequencing analysis compared with the traditional culture method revealed the coincidence rate was 100%. Via the MALDI-TOF-MS method, the genus coincidence rate was 100%. The identification rate above 99.9% was 17, above 90% was 32, above 80% was 26. All the results were credible. But its coincidence rate of serotypes is not high. 75 Salmonella, the highest rate of drug resistance was Ampicillin (69.3%, 52/75), followed by ampicillin/sulbactam (44%, 33/75) and nalidixic acid (42.7%, 32/75). 75 Salmonella were detected 19 strains of extended-sptectrum beta-lactam antimicrobial resistance, accounting for 25.3%. Among 19 strains had 15 carrying blaCTX-M gene (8 were blaCTX-M-14, 2 were blaCTX-M-9, 1 was blaCTX-M-34, 2 were blaCTX-M-3, 2 were blaCTX-M-15), 8 strains carried blaTEM-1 gene, 4 strains carried blaOXA-1 gene.Conclusion 16S rRNA gene sequencing method is as the gold standard for identification of bacteria, known for its fast and accurate, a supplement traditional methods of identification method. MALDI-TOF-MS method can quickly identify Salmonella, but only directional prompts serotypes in the research mode, and therefore it needs to be identified by other assistive technologies. Salmonella causes diarrhea in children resistant to multiple antibiotics, third generation cephalosporins resistance is mainly caused by CTX-M type.

Key words: Salmonella, 16S rRNA gene sequencing analysis, matrix assisted laser desorption ionization time of flight mass spectrometry, antimicrobial resistant, blaCTX-M