To understand the epidemiological characteristics and antimicrobial resistance of Esche-richia coli in free-range Tibetan pig populations,fecal samples from these pigs were collected be-tween 2021 and 2023 for pathogen isolation and identification.The isolated strains underwent anal-ysis of pathogenicity categories,phylogenetic grouping,and antimicrobial susceptibility profiles,a-long with resistance gene detection and mouse pathogenicity testing.The results showed that 123 strains of E.coli were isolated from 132 fecal samples.Enteropathogenicity tests revealed that 42.28％were EAEC(52/123),7.32％were EPEC(9/123),and 3.25％were STEC/EHEC(4/123).Phylogenetic analysis indicated that 78.86％(97/123)belonged to group A,while 11.38％(14/123)belonged to group B1.Antimicrobial susceptibility tests for 22 drugs showed the highest resistance rate to amoxicillin at 98.37％(121/123),followed by sulfamethoxazole at 73.98％(91/123).Resistance rates for ampicillin,tetracycline,erythromycin,and trimethoprim ranged from 48.78％to 51.22％.Furthermore,78.86％(97/123)of the isolates were resistant to three or more antibiotics.The detection of 52 drug-resistance genes in 10 categories showed that 15 drug-resist-ance genes were detected,and the detection rate was 28.85％(15/52).Among individual resistance genes,tetA had the highest detection rate at 63.41％(78/123),followed by tetB and qnrS with de-tection rates of 48.78％(60/123)and 38.21％(47/123),respectively.This study demonstrates that EAEC is the predominant strain of E.coli in free-range Tibetan pigs,with groups A and B1 being the major phylogenetic groups.The isolates exhibited a high degree of multidrug-resistant pheno-types,and the detection rates of resistance genes were also high.E.coli carrying virulence genes cause different degrees of pathological changes in the mouse ileum.The research results have sig-nificant public health implications and provide theoretical basis for the prevention,treatment,and clinical medication of E.coli disease in Tibetan pigs.

To understand the epidemiological characteristics and antimicrobial resistance of Esche-richia coli in free-range Tibetan pig populations,fecal samples from these pigs were collected be-tween 2021 and 2023 for pathogen isolation and identification.The isolated strains underwent anal-ysis of pathogenicity categories,phylogenetic grouping,and antimicrobial susceptibility profiles,a-long with resistance gene detection and mouse pathogenicity testing.The results showed that 123 strains of E.coli were isolated from 132 fecal samples.Enteropathogenicity tests revealed that 42.28％were EAEC(52/123),7.32％were EPEC(9/123),and 3.25％were STEC/EHEC(4/123).Phylogenetic analysis indicated that 78.86％(97/123)belonged to group A,while 11.38％(14/123)belonged to group B1.Antimicrobial susceptibility tests for 22 drugs showed the highest resistance rate to amoxicillin at 98.37％(121/123),followed by sulfamethoxazole at 73.98％(91/123).Resistance rates for ampicillin,tetracycline,erythromycin,and trimethoprim ranged from 48.78％to 51.22％.Furthermore,78.86％(97/123)of the isolates were resistant to three or more antibiotics.The detection of 52 drug-resistance genes in 10 categories showed that 15 drug-resist-ance genes were detected,and the detection rate was 28.85％(15/52).Among individual resistance genes,tetA had the highest detection rate at 63.41％(78/123),followed by tetB and qnrS with de-tection rates of 48.78％(60/123)and 38.21％(47/123),respectively.This study demonstrates that EAEC is the predominant strain of E.coli in free-range Tibetan pigs,with groups A and B1 being the major phylogenetic groups.The isolates exhibited a high degree of multidrug-resistant pheno-types,and the detection rates of resistance genes were also high.E.coli carrying virulence genes cause different degrees of pathological changes in the mouse ileum.The research results have sig-nificant public health implications and provide theoretical basis for the prevention,treatment,and clinical medication of E.coli disease in Tibetan pigs.

OBJECTIVETo compare the determination methods of fiber number concentration between China and WHO.

METHODSIndividual fiber samplings were conducted at a RCF manufacturing enterprise for 40 types of work. Flow rate was set as 2 L/min and lasted 2 to 4 hours. We used acetone-triacetin to prepare samples. The rules of two methods were used to count fibers for each sample respectively. The differences between the results of two methods were compared using the sign-rank test, and the correlation between the two methods' counting results were evaluated by the Spearsman rank correlation analysis.

RESULTSThe results of WHO counting rule were higher than those of Chinese counting rule for the same sample. The ratios of WHO method to Chinese method ranged from 1.88 to 3.70. Paired sign-rank test found the statistically significant differences of the results between the two methods (P<0.01). The rank correlation coefficient of the results by two rules counting ranged between 0.621 to 0.975, suggested positive correlation (P<0.01). The possible reasons of the difference between the two methods included the difference between the shapes of asbestos fiber and man-made mineral fiber, and counting rules of two methods.

CONCLUSIONThe results of WHO counting method is higher than those of Chinese counting method. High correlations between the results of the two methods were observed.

Asbestos ; analysis ; Chemistry Techniques, Analytical ; methods ; China ; Humans ; Mineral Fibers ; analysis ; Specimen Handling ; World Health Organization