Objective: To investigate the status of antibiotic exposure in third grade primary school students in Shenzhen,so as to provide evidence for the scientific management of antibiotic use and reduction of population health risks. Methods: From 1 September to 30 October 2021, 200 third grade students from 8 primary schools in Luohu District of Shenzhen were selected by cluster random sampling as research subjects. The body composition was measured, urine samples were collected, and the contents of 35 antibiotics in the samples were detected by mass spectrometry. Relevant dietary habit information of the subjects was collected via questionnaires. The Chi square test was used to compare the detection rate of antibiotics among different genders and weight grades. The Logistic regression model was adopted to evaluate the correlation between the target antibiotic detection rate and dietary habits. Results: At least one type of antibiotic was detected in 198 of the subjects with an overall detection rate of 99.0% . Among the 35 target antibiotics, 23 were detected with detection rates ranging from 0.5%-69.5%. Quinolones had the highest detection rate of 86.5% , followed by macrolides and sulfonamides with detection rates of 77.5% and 76.5%, respectively. The detection rate of antibiotics was 98.3% in boys and 100.0% in girls with no statistically significant difference ( χ 2=1.35, P >0.05). The detection rates of quinolones, macrolides, and sulfonamides varied significantly among children with different BMI categories ( χ 2=38.18, 12.45, 9.76 , all P <0.05). The multivariate Logistic regression model analysis showed that the macrolide detection rate was affected by genders( OR =0.42) and the sulfonamide detection rate was significantly correlated with the frequency of dairy product consumption and being overweight( OR =2.01)(both P <0.05). Enrofloxacin was associated with the weekly consumption frequency of livestock meat such as pork, beef and mutton, as well as the weekly consumption frequency of poultry meat such as chicken, duck and goose ( OR = 2.81,2.17,both P <0.05). Trimethoprim was associated with the weekly frequency of drinking pure milk ( OR =5.49, P < 0.05 ). Conclusions Third grade primary school students in Shenzhen are generally exposed to low dose antibiotics. Macrolides, quinolones, and sulfonamides may be associated with the risk of obesity in primary school students.

Objective: To analyze the correlation between the levels of vitamin A, vitamin D, vitamin E with body fat mass percentage(FMP) as well as lifestyle factors among primary school students, so as to provide references for exploring the vitamin nutritional status of primary school students and its potential influencing factors. Methods: From September 1 to October 30, 2021, a cluster sampling method was used to select 750 thirdgrade students from eight primary schools in Luohu District, Shenzhen. Their body composition was measured, and blood samples were collected to detect the serum levels of vitamin A, vitamin D, and vitamin E using a mass spectrometer. Dietary and exercise habits were collected through questionnaires. Mann-Whitney U test and Kruskal-Wallis H rank sum test were used for inter group comparisons, spearman correlation was used for correlation analysis,and Logistic regression model was used to analyze the association between lifestyle and vitamin content. Results: The overall level of vitamin A in school aged children was 0.4 (0.4, 0.5) mg/L, with a deficiency rate of 0 and a marginal deficiency rate of 5.1%; the level of vitamin D was 26.0 (22.0, 30.0) ng/mL, with a deficiency rate of 0.4% and an insufficiency rate of 12.7%; the content of vitamin E was 11.8 (10.1, 13.5) mg/L, with an insufficiency rate of 0.8%. Spearman correlation analysis showed that vitamin A was positively correlated with FMP in the total population, boys, girls, and normal weight population ( r =0.18, 0.18, 0.20, 0.10), and vitamin D was positively correlated with FMP in the total population and obese population ( r =0.08,0.16)(all P <0.05). Logistic regression analysis showed that marginal deficiency of vitamin A was associated with consumption of animal, snack, and dairy/egg/bean foods ( OR =0.45, 0.55, 0.59); whether vitamin D was deficient was influenced by gender ( OR =2.65) and exercise ( OR = 1.96 ) (all P <0.05). Conclusion Vitamin A, vitamin D and vitamin E levels are associated with body fat percentage, with significant variations in vitamin status among individuals of different body types, necessitating targeted supplementation.