Objective To analyze the serotypes distribution characteristics of salmonella infection in infants below 2 years old in Dongguan.Methods Feces samples collected in children below 2 years old with diarrhea,caused by salmonella infection,were cultured for salmonella isolates,which were then identified for serotypes.The distribution characteristics of different serotypes of salmonella were analyzed.Results A total of 369 strains of salmonella were isolated,including 36 serotypes.The most common three serotypes were Salmonella typhimurium(S.ty),Salmonella stanley(S.st) and Salmonella enteritidis(S.en),which accounted for 68.7%.In all infants with diarrhea,there were 253 boys and 143 girls,and the male:female ratio was 1.77∶1.The average age of infants was (9.3±2.3) months.In male and female infants,the most serotype was S.ty,accounting for 62.3% and 53.3%,but the least serotypes in male and female infants were S.st(16.8%) and S.en(19.0%) respectively.S.ty was the most common serotype in different age groups.The least serotypes in low-age group(0-5.99 months) and middle-age group(6-11.99 months)were S.st(18.4%) and S.en(14.4%) respectively.In high-age group(12-24 months),the proportion of S.st and S.en were both 21.8%.The diversity of salmonella serotypes in male infants was higher than female infants,and with the increasing of age,the diversity was more obvious.Conclusion There could be unique serotype distribution characteristics of salmonella infection in infants with diarrhea,and the diversity of salmonella serotypes should be paid more attention.

Objective:To identify and characterize one Spiroplasma strain (designated as DGKH1) isolated from the blood of a patient with sepsis. Methods:The traditional bacterial culture, staining, morphological observation, physiological and biochemical identification, 16S rRNA gene sequencing, phylogenetic analysis, genome sequencing, and the genome-related index analysis were performed to accurately determine the taxonomic status of the strain DGKH1. Antibiotic susceptibility testing was performed using a specific kit for culturing and testing Ureaplasma urealyticum/ Metamycoplasma hominis. Results:The strain DGKH1 could weakly grow on Columbia blood agar, chocolate agar, and Haemophilus chocolate 2 agar. However, it did not grow in liquid culture medium containing tetracycline (4 μg/ml), doxycycline (1 μg/ml), minocycline (1 μg/ml), josamycin (2 μg/ml), roxithromycin (1 μg/ml), clarithromycin (1 μg/ml), or telithromycin (1 μg/ml). DGKH1 resembling Metamycoplasma hominis formed "fried egg-like colonies" on Mycoplasma solid culture medium. DGKH1 could not be stained by Gram staining. When observed under transmission electron microscopy (TEM) using phosphate buffer as the matrix, the bacteria were spiral-shaped. Results of 16S rRNA gene sequence alignment showed that DGKH1 was highly similar (99.85%) to Spiroplasma eriocheiris CCTCC M 207170 T. However, the urea decomposition test was positive, which was different from all of the known Spiroplasma species. The phylogenetic analysis based on whole genome showed that DGKH1 was clustered in a small branch along with Spiroplasma eriocheiris CCTCC M 207170 T. However, the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains were 94.14% and 56.00%, respectively, both below the threshold for prokaryotic species identification. Conclusions:DGKH1 represented a potential new species of genus Spiroplasma, closely related to Spiroplasma eriocheiris. Some microbiological characteristics of DGKH1 were similar to Mycoplasmas. However, the natural host and epidemiological data of DGKH1 need to be further studied.