Establishment and evaluation of a reference strain of Stenotrophomonas maltophilia

Objective To systematically evaluate the Chinese clinical strain 11066 and establish a reference strain of Stenotrophomonas maltophilia in China.

Methods According to the Technical Requirements for Evaluation of National Standard Strains of Pathogenic Microorganisms(WS/T 812－2022), the morphology, motility, culture conditions, biochemical reactions, drug sensitivity, mass spectrometry of the Chinese S. maltophila isolate 11066 were tested, as well as 16S rRNA sequencing, multilocus sequence typing analysis, and whole genome sequencing. The strain was expand cultured and libraries of main seed and working strain were established.

Results Strain 11066 is a Gram negative bacterium, with 1–4 extreme flagella visible under electron microscopy. It grows well on blood plates and other nutrient agar under conditions of 15–37 ℃, pH 5–10, and 0–5% salt concentration. It was motivation positive, has positive results in nitrate reduction test, hydrolysis heptyl and gelatin test and can utilize glucose, mannose, N-acetylglucosamine, maltose, citric acid, and malic acid as carbon sources. It was resistance to 18 commonly used antibiotics against Gram negative bacteria such as amikacin and cefoxitin. The biological characteristics of the strains in the main seed and working libraries were stable, and the information on passage was complete. The strain has been deposited to the National Pathogen Resource Center with preservation number.

Conclusion The Chinese clinical S. maltophilia isolate 11066 has clear source information and typical biological and genetic characteristics of S. maltophilia. It has been evaluated according to national standard strain evaluation standards and stored in recognized source/preservation centers. It can be used as a standard/reference strain for quality control in clinical testing and basic scientific research.