GLOBAL WATER PATHOGEN PROJECT PART THREE. SPECIFIC EXCRETED PATHOGENS: ENVIRONMENTAL AND EPIDEMIOLOGY ASPECTS PATHOGENIC MEMBERS OF ESCHERICHIA COLI & SHIGELLA SPP. SHIGELLOSIS Cristina Garcia-Aljaro University of Barcelona Barcelona, Spain Maggy Momba Tshwane University of Technology South Africa Pretoria, South Africa Maite Muniesa University of Barcelona Barcelona, Spain Copyright: This publication is available in Open Access under the Attribution-ShareAlike 3.0 IGO (CC-BY-SA 3.0 IGO) license (http://creativecommons.org/licenses/by-sa/3.0/igo). By using the content of this publication, the users accept to be bound by the terms of use of the UNESCO Open Access Repository (http://www.unesco.org/openaccess/terms-use-ccbysa-en). Disclaimer: The designations employed and the presentation of material throughout this publication do not imply the expression of any opinion whatsoever on the part of UNESCO concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The ideas and opinions expressed in this publication are those of the authors; they are not necessarily those of UNESCO and do not commit the Organization. Citation: Garcia-Aljaro, C., Momba, M. and Muniesa, M. 2017. Pathogenic members of Escherichia coli & Shigella spp. Shigellosis. In: J.B. Rose and B. Jiménez-Cisneros, (eds) Global Water Pathogens Project. http://www.waterpathogens.org (A. Pruden, N. Ashbolt and J. Miller (eds) Part 3 Bacteria) http://www.waterpathogens.org/book/ecoli Michigan State University, E. Lansing, MI, UNESCO. Acknowledgements: K.R.L. Young, Project Design editor; Website Design (http://www.agroknow.com) Published: January 15, 2015, 10:31 am, Updated: October 30, 2017, 12:18 pm Pathogenic members of Escherichia coli & Shigella spp. Shigellosis Summary surprising long-term survival in these substrates. E. coli’s role as an indicator organism of fecal pollution Shigella spp. and pathogenic Escherichia coli are Gram- is described in another chapter, but as such it is always negative, facultative anaerobe bacteria belonging to the present in relatively high amounts whenever feces is genus Shigella, within the familyEnterobacteriaceae . present. E. coli is therefore considered a useful surrogate Shigella spp. cause a spectrum of diseases including of pathogenic E. coli and Shigella, however, as most bacilliary dysentery (shigellosis), a disease characterized by pathogenic E. coli are lactase-negative, they are not the destruction of the colonic mucosa that is induced upon detected in standard water quality media used to bacterial invasion. Although Shigella are divided into four enumerate E. coli. Hence, molecular methods targeting species (S. dysenteriae, S. flexneri, S. boydii, S. sonnei) its virulence factors are used to distinguish pathogenic separation from pathogenic E. coli is based on historical variants from commensal, non-pathogenic ubiquitous E. coli precedence. Clinically and diagnostically, Shigella spp. are strains. The problem is that the mosaic genetic structure of similar to enteroinvasive E. coli (EIEC), sharing many of the these strains, containing most virulence genes encoded in same virulence factors andbiochemical characteristics. mobile genetic elements that might be present or not, can Shigella dysenteriae is considered the most virulent, and make it hard to resolve commensal E. coli. Moreover, the can produce the potent cytotoxin Shigatoxin, closely related detection of the mobile genetic elements free in water to Stx1 in pathogenic E. coli. bodies, as happens with Stx phages, add a further level of complexity in identifying infectious, pathogenic E. coli. Pathogenic E. coli consist of a group of serotypes linked with severe human intestinal and extra-intestinal illnesses. It is generally assumed, although with limited actual They combine a set of virulence factors used to separate data, that fate and transport of fecal indicatorE. coli is them into six groups (enteropathogenic: EPEC,indicative of the intracellular, Shigella spp. and pathogenic enterotoxigenic: ETEC, enteroaggregative: EAggEC, E. coli’s environmental behavior. Most data have been enteroinvasive: EIEC, enterohaemorrhagic: EHEC and collected on Shigella spp. and EHEC, and unless otherwise diffusely adherent: DAEC). One of their most dangerous noted in this Chapter, commensalE. coli results can group is EHEC due to their virulence factors that produce probably be extrapolated to provide rates of inactivation of Shiga toxins (Stx), which can result in hemolytic uremic the pathogenic members. syndrome. The majority of the genes coding for virulence factors in E. coli are encoded in mobile genetic elements, and the difference between non-pathogenic and pathogenic Shigella and pathogenic strains is largely a result of the incorporation or loss of these elements. Escherichia coli Shigella spp. have humans as the most common 1.0 Epidemiology of the Disease and reservoir although infections have also been observed in Pathogen(s) other primates. Many pathogenicE. coli are zoonotic pathogens, while others have humans as the only known 1.1 Global Burden of Disease reservoir. Both groups are geographically ubiquitous and infections are reported wherever humans reside. 1.1.1 Global distribution Both Shigella spp. and pathogenic E. coli are spread Shigella spp. and pathogenic E. coli are ubiquitous through the fecal-oral route, and transmission is typically Gram-negative rod shaped bacilli largely associated with through: ingestion of contaminated foods (washed with mammalian or avian hosts, classified in the genus Shigella, fecally contaminated water, or handled with poor hygiene), within the family Enterobacteriaceae (The et al., 2016). drinking contaminated water (or via recreational waters) or Both pathogens are transmitted through the fecal-oral by person-to-person contact. Both may contaminate waters route. Shigella spp. can induce a symptomatic infection via through feces from humans and forE. coli also from domestic animals and wild birds. These pathogens enter an exceptionally low infectious dose (<10 bacteria), as water bodies through various ways, including sewage opposed to the various diarrheagenicE. coli pathovars, overflows, sewage systems that are not working properly, which have infectious doses of at least four orders of animal manure runoff, and polluted urban storm water magnitude greater (Kothary and Babu, 2001). runoff. Wells may be more vulnerable to such contamination after flooding, particularly if the wells are 1.1.2.1 Shigella spp. shallow, have been dug or bored, or have been submerged by floodwater for long periods of time. Occurrence of E. coli Shigella is typically an inhabitant of the gastrointestinal O157 and other serotypes carryingstx 2 gene in raw tract of humans and other primatesGermani ( and municipal sewage and animal wastewater from several Sansonetti, 2003; Strockbine and Maurelli, 2005; WHO, origins has been described. In addition, since land 2008). The first report on the isolation and characterization application is a routine procedure for the disposal of both of bacteria causing bacillary dysentery, later named animal (manure) and human waste of fecal origin (direct Shigella, was published by Japanese microbiologist Kiyoshi deposition or sludge), the presence ofShigella and Shiga at the end of the 19th century (Schroeder and Hilbi, pathogenic E. coli has also been described there, and shows 2008). By means of the fecal route of transmission, Shigella 3 Pathogenic members of Escherichia coli & Shigella spp. Shigellosis can be also found in fecally contaminated material and described in the following sections. While some groups are water but shows a low survival rate without the optimal frequently associated to developing regions (ETEC, EPEC, acidic environment in the intestinal tract. Asymptomatic EIEC), other groups are predominant in developed regions carriers of Shigella can exacerbate the maintenance and and often zoonotic (EHEC). spread of this pathogen, particularly where sanitation is poor or non-existent. 1.1.2 Symptomatology Although Shigella spp. have been awarded their own genus which is divided into four speciesShigella ( 1.1.2.1 Shigella spp. dysenteriae, Shigella flexneri, Shigella boydii, Shigella sonnei), its separation from E. coli nowadays is only historic Shigella is a pathogen with a low infectious dose, (Karaolis et al., 1994; Pupo et al., 2000; The et al. 2016). capable of causing disease in otherwise healthy individuals. These bacterial pathogens are largely responsible for Infection with Shigella spp. causes a spectrum of diseases shigellosis or bacillary dysentery. ranging from a mild watery diarrhea to severe dysentery (shigellosis). The dysentery stage of disease correlates with Globally, Shigella species are not evenly distributed. S. extensive bacterial colonization of the colonic mucosa, and dysenteriae is mainly found in densely populated areas of the destruction of the colonic mucosa that is induced upon South America, Africa and Asia.S. flexneri usually bacterial invasion (Schroeder and Hilbi, 2008). Shigella predominates in areas where endemic shigellosis occurs, spp. are common etiological agents of diarrhea among while S. boydii occurs sporadically, with the exception in travelers to less developed regions of the world, and tend to India where it was first identified.S. sonnei is mostly reported from developed regions of Europe and North produce a more disabling illness than enterotoxigenicE. America