Abstract: Objective: To investigate the microbial community composition and structure of the processing workshop of infant formula in Fujian province in 2024, to reveal the microbial diversity present in the workshop as well as the changes in the distribution of microorganisms among different functional zones, and to unveil the drug resistance of the isolates. Methods: A stratified random sampling strategy was employed to collect surface microbiota, airborne planktonic bacteria and sedimentary microbes from the selected manufactures by aseptic swabbing, six-stage Andersen air sampling, and plate exposure methods, respectively. The purified isolates were analyzed by 16S rDNA gene sequencing and multi-sequence alignment and phylogenetic tree construction were carried out using the MEGA software. To ensure taxonomic accuracy, the VITEK? 2 Compact fully automatic microbial identification system was utilized for physiological and biochemical characterization, and phenotypic validation was performed by referring to the latest Bergey’s manual of systematic bacteriology. A dual verification framework integrating molecular and traditional phenotypic identification was thereby established. Antimicrobial susceptibility testing was performed using standardized protocols, and based on the data obtained, a heatmap was generated. Results: A total of 355 isolates were obtained, belonging to 19 genera. Out of these, 61.1% were Gram-positive bacteria, and 38.9% were Gram-negative bacteria, Staphylococcus, Bacillus, and Pseudomonas being the major ones, accounting for 72.95% of the total collected strains. Among them, Staphylococcus has the highest distribution rate, accounting for 33.80% of all isolated strains The phylogenetic analysis and spatial distribution pattern of Staphylococcus revealed personnel movement and material handling to be the principal contamination vectors. Antimicrobial susceptibility testing demonstrated that coagulase-negative staphylococci (CoNS) showed 100% susceptibility to teicoplanin, vancomycin and linezolid and 20%–90% susceptibility to penicillin G (benzylpenicillin), erythromycin, methicillin and clindamycin. Some of the environmental isolates showed multi-drug resistance. Conclusion: Staphylococcal species were the dominant microbial population in the infant formula production environment, with workshop operators being their largest vector. The identification of antimicrobial-resistant isolates underscores the need for enhanced personnel sanitation and air purification to reduce the risk of microbial contamination.

Key words: infant formula; production workshop; microorganisms; 16S rDNA gene sequencing technology; community analysis; drug resistance

摘要： 目的：了解2024年福建省婴幼儿配方乳粉车间微生物种类及群落结构，以揭示车间中存在的微生物多样性以及微生物在不同功能间的分布变化和耐药性。方法：按照分层随机抽样方法，对选定企业分别通过无菌拭子擦拭法、六级安德森空气采样器法、平板暴露法对生产车间表面微生物、浮游菌及沉降菌进行采集。分离纯化环境微生物后，首先采用16S rDNA基因测序技术构建系统发育树，通过MEGA软件进行多序列比对和进化分析。为确保鉴定结果的准确性，同步应用VITEK? 2 Compact全自动微生物鉴定系统进行生理生化特征分析，并参照最新版《伯杰氏系统细菌学手册》进行表型特征验证，建立分子生物学与传统表型鉴定相结合的双重验证体系；同时，应用药敏分析系统对采集所得微生物进行药敏试验，基于药敏数据构建热图进行可视化分析。结果：共采集环境微生物355 株，分属为19 个种属，其中革兰氏阳性菌占61.1%，革兰氏阴性菌占38.9%；其主要构成为葡萄球菌属（Staphylococcus）、芽孢杆菌属（Bacillus）、假单胞菌属（Pseudomonas），占总采集菌株的72.95%，其中葡萄球菌属的区域采集分布率最高，占所有分离菌株的33.8%；对主要葡萄球菌属构建进化树及不同区域的数量统计表明，人员和物料的流动依然作为首要污染载体。药敏试验表明，凝固酶阴性葡萄球菌（coagulase-negative staphylococci，CoNS）对替考拉宁、万古霉素、利奈唑胺抗生素的敏感率为100%，对青霉素G（苄青霉素）、红霉素、甲氧西林、克林霉素抗菌药的敏感率占所测试CoNS的20%～90%不等，且所采集的环境菌群已有部分出现多重耐药的特点。结论：婴幼儿配方乳粉车间微生物主要以葡萄球菌为主，人体是微生物的最大载体，环境微生物呈现出不同程度的耐药特性，建议通过加强人员消毒和净化流程等有效措施，以降低产品微生物污染风险。

关键词: 婴幼儿配方乳粉；生产车间；微生物；16S rDNA基因测序技术；群落分析；耐药性