Colonization factors of Escherichia coli O157:H7 in pigs

Escherichia coli O157:H7 causes severe hemorrhagic colitis in people. The main source of infection by E. coli O157:H7 is improperly cooked, or handled, contaminated food. E. coli O157:H7 has two well-described virulence factors: intimin and Shiga toxins. Research presented in this document utilized strains of E. coli O157:H7 that were mutated in genes that encoded a quorum sensing molecule, long polar fimbriae, and intimin. Gnotobiotic and conventionally reared pigs were infected to demonstrate whether the mutated strains were impaired in their ability to colonize or create disease when compared to the parent strain of E. coli O157:H7.;Mutation of the luxS gene, the product of which was a quorum sensing communicative molecule Al-2, was the first mutant of E. coli O157:H7 presented. AI-2 positively influences the bacterium to transcribe and translate genes that are necessary for bacterial attachment to enterocytes. Natural host hormones, epinephrine and norepinephrine, can override the luxS mutation given to the bacteria. The mutation in luxS had minimal effect on the colonization capability for E. coli O157:H7 possibly due to the provision of hormones from the intestinal tract of the pigs.;The second set of E. coli O157:H7 mutants had genes disrupted that were homologous to long polar fimbriae genes in Salmonella. The fimbriae may contribute to the initial adherence of E. coli O157:H7 to the enterocytes. The results of the long polar fimbriae studies indicated the lpf genes are not critical for virulence; however, they may aid E. coli O157: H7 in the colonization of gnotobiotic and conventionally reared pigs.;The third E. coli O157:H7 mutant was an intimin mutant. Several studies have shown that E. coli O157:H7 can be recovered from the tonsils from infected conventional pigs. In some instances, the recovery from tonsils exceeded that from the feces or any intestinal organ. It was concluded that intimin is not required for colonization of conventional pigs by E. coli O157:H7; nor does it preferentially colonize a particular area of the alimentary tract, but can remain at low levels throughout the tract.;These three studies may contribute to the idea that redundancy of adherence mechanisms may allow E. coli O157:H7 a competitive advantage in the colonization process

Colonization and Transmission of Escherichia Coli O157:H7 in Swine

Escherichia coli O157:H7 and other serogroups of Shiga toxin-producing E.coli (STEC) have emerged over the last several decades as a significant cause of food-borne illness in the United States. Approximately 5-10% of people clinically infected by these bacteria develop a systemic disease, hemolytic uremic syndrome, which has a fatality rate of approximately 5%. The Centers for Disease Control estimates that STEC cause some 110,000 illnesses and 90 deaths annually in the United States (Mead et al. 1999). In addition, the economic consequences of recalling large lots of food for public health reasons are significant. Cattle are considered to be the primary reservoir for STEC. Depending on the season, the methods used for bacterial culture and the age of the animals, the prevalence of E. coli O157:H7 in U.S. cattle ranges from 2-28% (Hancock et al. 1994; Elder et al. 2000). E.coli O157:H7 has also been recovered from other ruminants such as sheep (Kudva et al. 1996) and deer (Keene et al. 1997; Sargeant et al. 1999)

Salmonella typhimurium fecal shedding following Salmonella choleraesuis-thyphimurium vaccination via drinking water and subsequent challenge

Salmonella typhimurium (ST) is a primary cause of enteritis and subclinical production losses in growing or finishing swine. Due to the zoonotic potential, intervention programs for ST have been established attempting to reduce carcass contamination. The objective of this study was to evaluate Salmonella fecal shedding of pigs vaccinated with a commercial, avirulent live culture (ALC) Salmonella Choleraesuis-Typhimurium vaccine when challenged with virulent ST

Long Polar Fimbriae Contribute to Colonization by \u3ci\u3eEscherichia coli\u3c/i\u3e O157:H7 In Vivo

The contribution of long polar fimbriae to intestinal colonization by Escherichia coli O157:H7 was evaluated in sheep, conventional pigs, and gnotobiotic piglets. E. coli O157:H7 strains with lpfA1 and lpfA2 mutated were recovered in significantly lower numbers and caused fewer attachment and effacement lesions than the parent strain

Emergence of a Tetracycline-Resistant Campylobacter jejuni Clone Associated with Outbreaks of Ovine Abortion in the United States

Campylobacter infection is one of the major causes of ovine abortions worldwide. Historically, Campylobacter fetus subsp. fetus was the major cause ofCampylobacter-associated abortion in sheep; however, Campylobacter jejuni is increasingly associated with sheep abortions. We examined the species distribution, genotypes, and antimicrobial susceptibilities of abortion-associatedCampylobacter isolates obtained from multiple lambing seasons on different farms in Iowa, Idaho, South Dakota, and California. We found that C. jejuni has replacedC. fetus as the predominant Campylobacter species causing sheep abortion in the United States. Most strikingly, the vast majority (66 of 71) of the C. jejuni isolates associated with sheep abortion belong to a single genetic clone, as determined by pulsed-field gel electrophoresis, multilocus sequence typing, and cmp gene (encoding the major outer membrane protein) sequence typing. The in vitro antimicrobial susceptibilities of these isolates to the antibiotics that are routinely used in food animal production were determined using the agar dilution test. All of the 74 isolates were susceptible to tilmicosin, florfenicol, tulathromycin, and enrofloxacin, and 97% were sensitive to tylosin. However, all were resistant to tetracyclines, the only antibiotics currently approved in the United States for the treatment of Campylobacter abortion in sheep. This finding suggests that feeding tetracycline for the prevention of Campylobacter abortions is ineffective and that other antibiotics should be used for the treatment of sheep abortions in the United States. Together, these results indicate that a single tetracycline-resistant C. jejuniclone has emerged as the major cause of Campylobacter-associated sheep abortion in the United States

Mapping and enumerating houses and households to support malaria control interventions on Bioko Island.

BACKGROUND: Housing mapping and household enumeration are essential for the planning, implementation, targeting, and monitoring of malaria control interventions. In many malaria endemic countries, control efforts are hindered by incomplete or non-existent housing cartography and household enumeration. This paper describes the development of a comprehensive mapping and enumeration system to support the Bioko Island Malaria Control Project (BIMCP). RESULTS: A highly detailed database was developed to include every housing unit on Bioko Island and uniquely enumerate the associated households residing in these houses. First, the island was divided into a virtual, geo-dereferenced grid of 1 × 1 km sequentially numbered map-areas, each of which was in turn subdivided into one hundred, 100 × 100 m sequentially numbered map-sectors. Second, high-resolution satellite imagery was used to sequentially and uniquely identify all housing units within each map-sector. Third, where satellite imagery was not available, global positioning systems (GPS) were used as the basis for uniquely identifying and mapping housing units in a sequential manner. A total of 97,048 housing units were mapped by 2018, 56% of which were concentrated in just 5.2% of Bioko Island's total mapped area. Of these housing units, 70.7% were occupied, thus representing uniquely identified households. CONCLUSIONS: The housing unit mapping and household enumeration system developed for Bioko Island enabled the BIMCP to more effectively plan, implement, target, and monitor malaria control interventions. Since 2014, the BIMCP has used the unique household identifiers to monitor all household-level interventions, including indoor residual spraying, long-lasting insecticide-treated nets distribution, and annual malaria indicator surveys. The coding system used to create the unique housing unit and household identifiers is highly intuitive and allows quick location of any house within the grid without a GPS. Its flexibility has permitted the BIMCP to easily take into account the rapid and substantial changes in housing infrastructure. Importantly, by utilizing this coding system, an unprecedented quantity and diversity of detailed, geo-referenced demographic and health data have been assembled that have proved highly relevant for informing decision-making both for malaria control and potentially for the wider public health agenda on Bioko Island

Recombinant Iss as a Potential Vaccine for Avian Colibacillosis

Avian pathogenic Escherichia coli (APEC) cause colibacillosis, a disease which is responsible for significant losses in poultry. Control of colibacillosis is problematic due to the restricted availability of relevant antimicrobial agents and to the frequent failure of vaccines to protect against the diverse range of APEC serogroups causing disease in birds. Previously, we reported that the increased serum survival gene (iss) is strongly associated with APEC strains, but not with fecal commensal E. coli in birds, making iss and the outer membrane protein it encodes (Iss) candidate targets for colibacillosis control procedures. Preliminary studies in birds showed that their immunization with Iss fusion proteins protected against challenge with two of the more-commonly occurring APEC serogroups (O2 and O78). Here, the potential of an Iss-based vaccine was further examined by assessing its effectiveness against an additional and widely occurring APEC serogroup (O1) and its ability to evoke both a serum and mucosal antibody response in immunized birds. In addition, tissues of selected birds were subjected to histopathologic examination in an effort to better characterize the protective response afforded by immunization with this vaccine. Iss fusion proteins were administered intramuscularly to four groups of 2-wk-old broiler chickens. At 2 wk postimmunization, chickens were challenged with APEC strains of the O1, O2, or O78 serogroups. One week after challenge, chickens were euthanatized, necropsied, any lesions consistent with colibacillosis were scored, and tissues from these birds were taken aseptically. Sera were collected pre-immunization, postimmunization, and post-challenge, and antibody titers to Iss were determined by enzyme-linked immunosorbent assay (ELISA). Also, air sac washings were collected to determine the mucosal antibody response to Iss by ELISA. During the observation period following challenge, 3/12 nonimmunized chickens, 1/12 chickens immunized with 10 µg of GST-Iss, and 1/12 chickens immunized with 50 µg of GST-Iss died when challenged with the O78 strain. No other deaths occurred. Immunized chickens produced a serum and mucosal antibody response to Iss and had significantly lower lesion scores than nonimmunized chickens following challenge, regardless of the challenge strain. This study expands on our previous report of the value of Iss as an immunoprotective antigen and demonstrates that immunization with Iss can provide significant protection of chickens against challenge with three different E. coli strains.This article is from Avian Diseases 56, no. 1 (2012): 192–199, doi:10.1637/9861-072111-Reg.1.</p

Colonization factors of Escherichia coli O157:H7 in pigs

Escherichia coli O157:H7 causes severe hemorrhagic colitis in people. The main source of infection by E. coli O157:H7 is improperly cooked, or handled, contaminated food. E. coli O157:H7 has two well-described virulence factors: intimin and Shiga toxins. Research presented in this document utilized strains of E. coli O157:H7 that were mutated in genes that encoded a quorum sensing molecule, long polar fimbriae, and intimin. Gnotobiotic and conventionally reared pigs were infected to demonstrate whether the mutated strains were impaired in their ability to colonize or create disease when compared to the parent strain of E. coli O157:H7.;Mutation of the luxS gene, the product of which was a quorum sensing communicative molecule Al-2, was the first mutant of E. coli O157:H7 presented. AI-2 positively influences the bacterium to transcribe and translate genes that are necessary for bacterial attachment to enterocytes. Natural host hormones, epinephrine and norepinephrine, can override the luxS mutation given to the bacteria. The mutation in luxS had minimal effect on the colonization capability for E. coli O157:H7 possibly due to the provision of hormones from the intestinal tract of the pigs.;The second set of E. coli O157:H7 mutants had genes disrupted that were homologous to long polar fimbriae genes in Salmonella. The fimbriae may contribute to the initial adherence of E. coli O157:H7 to the enterocytes. The results of the long polar fimbriae studies indicated the lpf genes are not critical for virulence; however, they may aid E. coli O157: H7 in the colonization of gnotobiotic and conventionally reared pigs.;The third E. coli O157:H7 mutant was an intimin mutant. Several studies have shown that E. coli O157:H7 can be recovered from the tonsils from infected conventional pigs. In some instances, the recovery from tonsils exceeded that from the feces or any intestinal organ. It was concluded that intimin is not required for colonization of conventional pigs by E. coli O157:H7; nor does it preferentially colonize a particular area of the alimentary tract, but can remain at low levels throughout the tract.;These three studies may contribute to the idea that redundancy of adherence mechanisms may allow E. coli O157:H7 a competitive advantage in the colonization process.</p

Colonization of Gnotobiotic Piglets by a \u3ci\u3eluxS\u3c/i\u3e Mutant Strain of \u3ci\u3eEscherichia coli\u3c/i\u3e O157:H7

Gnotobiotic piglets inoculated with Escherichia coli O157:H7, its luxS mutant derivative, or nonpathogenic E. coli were evaluated for attaching and effacing lesions. Although no differences in clinical symptoms were seen between pigs inoculated with the parent and those inoculated with the luxS mutant, the luxS mutant-inoculated pigs had a lower frequency of attaching and effacing lesions in the spiral colon than parent strain-inoculated pigs