Duration of stool colonization in healthy medical students with extended-spectrum-β-lactamase-producing Escherichia coli.

Objective To investigate the faecal colonization of Extended-Spectrum-β-Lactamase-producing Escherichia coli( E. coli) among healthy students in Fujian Medical University. Methods A total of 92 Fujian Medical University students were randomly recruited during september 2011. Each subject self-collected one fecal sample. Undiluted stool samples were cultured on chromID ESBLs plates to screen ESBLs E. coli. PCR and DNA sequencing were used to detect common β-Lactamase genes( SHV,TEM,CTX-M-1 groups,CTX-M-2 groups and CTX-M-9 groups) and randomly select five isolates of each genotype to sequence. Phylogenetic analysis of E. coli isolates was used multiplex PCR. Rsults 76( 82. 61%) ESBL-positive E. coli were isolated from faecal samples. 76. 32%( 58 /76),59. 21%( 45 /76),35. 53%( 27 /76),1. 32%( 1 /76) of the isolates were belong to CTX-M-9 groups,TEM,CTX-M-1 groups and SHV,respectively. Five strains of each group( CTX-M-1,CTX-M-9,TEM,and SHV) were randomly selected to sequence,and results revealed that they were all CTX-M-15,CTX-M-14,TEM-1 and SHV-12,respectively. Results of phylogenetic analysis revealed that the large majority,i. e 53. 95%( 41 /76),of the E. coli strains belonged to group A,38. 16%( 29 /76) and 5. 26%( 4 /76) were of group D and group B2,respectively; and 2. 63%( 2 /76) were of group B1. Condusion The stool colonization of ESBL-positive E. coli remained at a surprisingly high level in Fujian Medical University students. CTX-M-9 groups( CTX-M-14) is the most dominant genotype in ESBLs E. coli.