Molecular Epidemiological Investigation And Pathogenicity Research Of Uropathogenic Escherichia Coli(UPEC) In Parts Of Jiangsu Province

Urinary tract infections (UTIs) are among the most common human diseases in the world, causing significant morbidity and mortality. Most community-acquired UTIs are due to uropathogenic Escherichia coli (UPEC) infections. UPEC strains possess specialized virulence factors, enabling them to colonize and invade to the host, disrupt the host defense mechanisms, injure host tissues, and/or stimulate noxious host inflammatory response. The abilities of UPEC to grow extraintestinally may enable them to cause a variety of diseases, not just urinary tract ones.The research to UPEC is still in its infancy in China, so the related epidemiological data is quite deficiency, which has brought lots of difficulty to prevent and control single and/or mixed UTI caused by UPEC. Goal of this study is to collect UPEC isolates in parts of Jiangsu province, and have a good understanding of the UPEC molecular epidemiological situation in this region. For further study the pathogenesis and prevention measures of the UTI to settle the groundwork.This study is started from September2011to September2012, and in all183UPEC strains were isolated from the clinical cases of UTI in parts of Jiangsu. The O serotypes, phylogenetic groups and virulence factors by a series of molecular biological methods were determined. As a result, the most common O serotype was01serotype among all isolates. Meanwhile, other predominant O serotypes were015,075,012,026,06and074; in contrast, D and B2phylogenetic groups were the most common, accounting for41%of the isolates and30%, A and B1phylogenetic groups accounting for17%and12%, respectively.14virulence genes that has been associated with the ability of UPEC to survive in the urinary tract were chosen to detect. Molecular Koch’s postulates have been applied to virlulence factors expressed by UPEC. In the tested14virulence genes, TonB and DsdA possessed the highest prevalence rate,98%and97%, respectively. DegP, ompR and fimH positive rate is over90%; several virulence genes such as fliC, neuC, ireA and vat are not higher than23%in UPEC strains. In these183UPEC strains isolated, virulence genes more than ten of fourteen add to a total of56strains (30.6%). There were9strains (4.9%) harbouring less than five tested virulence genes and the rest118strains (64.5%) were moderate.According to research reported at home and abroad, the paper has analyzed the relationship of O serotype, phylogenetic group and the number of virulence genes, and selected several UPEC strains that came from common O serotype (O1,O4,O75) and popular serotype(O15, O26,O74) in parts of Jiangsu province. Based on1-day-old chickens lethal test, colonization and persistence in vivo of21-day-old SPF chickens,6-8-week-old BALB/c female mice pathogenic model, I found:1-day-old chickens lethal test results show that:the APEC strain E058, the UPEC strains strain U17inoculated chickens the mortality reached100%within24h, the tested UPEC strains S33and S100also reached100%within24h; S58, S128caused all chickens’ death until the second day and S85until the third day; Y19only caused2birds’ death within the second day and S19caused1bird’s death within the third day. While S22, S51, S73and negative control group were not result in the death of the chicken.The results of colonization and persistence in vivo of21-day-old SPF chickens show: compared with the highly pathogenic strain U17, the difference of the UPEC strain isolates S33’s pathogenicity is not significant (P>0.05); In addition to the liver and kidney, The results in other organs of S128strain showed significantly or extremely significantly difference lower than U17; the difference between S85and U17was extremely significantly yet, suggested S85strain’s pathogenic is lower than U17. Meanwhile the epidemic O serotype strains’(S73, S100, Y19in Jiangsu district) difference was also extremely significant than U17, indicating that the weak pathogenicity. According to the pathological analysis, we can see thick epicardial and lots of inflammatory cell infiltration and bacteria proliferation.In6-8weeks old BALB/c mouse infection model, compared with the highly pathogenic strain U17, combined with the count results of bacteria in the urine, bladder and kidney, initially showed that the S33strain’s pathogenicity was much stronger than U17, while UPEC isolate S73strain had weak pathogenicity or even non-pathogenicity. According to the pathological analysis, all UPEC isolates had not lead to6-8weeks old BALB/c mice systemic infection, heart, liver, spleen, lungs, did not show any pathological changes. And there were no any pathological changes in kidney and ureter, agreement with the foreign reports. However, some highly pathogenic strains (such as U17, S33, S128) can lead to capillary dilatation and congestion of the lamina propria of the bladder, loose organizational structure, showing varying degrees of inflammatory cell infiltration.In summary, the epidemic strain S33(04) possesed much stronger pathogenicity than U17. There were no obvious difference between S128strain (O1) and U17, that was to say they both had the equivalent pathogenicity, while S22who was also belong to the same01serotyoe did show weak pathogenicity. As a result, there was a certain positive correlation between the number virulence genes and pathogenicity to some extent. And Jiangsu popular074serotype strain (S100) also had a certain pathogenicity, no difference with the common serotype075strain (S85), O15,026serotypes strains were weak pathogenic or non-pathogenic.