Indicators of microbial quality *
Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse in Routledge Handbook of Water and Health, 2015
Waterborne infectious diseases are caused primarily by pathogenic bacteria, viruses, and protozoa and are associated with the presence of human or animal fecal material, since these microbes are generally transmitted via the “fecal–oral route” (Chapter 2). Of the several dozen known and suspected pathogens transmitted in water, recent evidence suggests that the relative contribution of specific microbes to the burden of disease varies widely by setting and population. Rotavirus, Cryptosporidium, enterotoxigenic Escherichia coli (ETEC), Shigella, Vibrio cholera, and Salmonella are among the most important globally (Kotloff et al. 2013). Although rapid, low-cost, simultaneous methods for detection of multiple pathogens in water is the focus of intense research, current methodological constraints limit our ability to rapidly and accurately identify all pathogens that may be present and determine whether they exist in quantities that pose risks to public health. Because some pathogens have low infectious doses, even as few as a single microbe, even small numbers of pathogens in water may contribute to increased risk of disease. Detecting them directly may therefore require concentration of large volumes of water. So, to assess water safety, we look for the common element that is associated with most of these microbes: human or animal feces, markers of which are more easily detected than specific pathogens.
Giardia outbreaks on Ship
Meera Chand, John Holton in Case Studies in Infection Control, 2018
Water aboard ships is always transported by way of water tanks and complex distribution systems and may additionally be used recreationally in swimming pools and spas. A range of pathogens can cause infections, which usually occur following ingestion of either contaminated water or ice or by contact with water through bathing or swimming. Infections also may occur through inhalation of aerosols. Of these infections, 86% of outbreaks were associated with passenger ships, and, in 57% of those cases, water or ice was confirmed as the source and was additionally suspected in 33% of cases. One-third of outbreaks were attributed to Enterotoxigenic Escherichia coli (ETEC), however other species such as Salmonella sp., Shigella sp., Cryptosporidium, norovirus, and Giardia were also documented. In 81% of outbreaks, contributing factors were identifiable and the documented outbreak associated with Giardia resulted from contaminated water loaded onto a ship and inadequate disinfection.
M cells and the follicle-associated epithelium
Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald in Principles of Mucosal Immunology, 2020
Some pathogenic bacteria such as Vibrio cholerae and enterotoxigenic Escherichia coli cause severe diarrheal disease without invasion. V. cholerae, for example, adhere to the epithelial glycocalyx using adhesive toxin-coregulated pili, form dense colonies, and then upregulate production of cholera toxin that diffuses through the glycocalyx to bind to a common glycolipid in enterocyte apical membranes. Endocytosis of the toxin initiates complex intracellular events that result in passage of the enzymatic toxin subunit into the cytoplasm, production of cyclic AMP, and apical secretion of chloride ions that drive massive loss of water into the intestinal lumen. Some vibrios, however, adhere to M cells and are rapidly endocytosed, transported into Peyer's patches, and processed by DCs (Figure 15.7). The resultant adaptive immune response leads to the secretion of IgA antibodies to V. cholera pili, lipopolysaccharide, and cholera toxin. These antibodies participate in the clearance of the adherent colonies and protection against subsequent challenge.
Enterotoxigenic Escherichia coli: intestinal pathogenesis mechanisms and colonization resistance by gut microbiota
Published in Gut Microbes, 2022
Yucheng Zhang, Peng Tan, Ying Zhao, Xi Ma
Enterotoxigenic Escherichia coli (ETEC) is the major enteric pathogen that account for the tens of millions of diarrheal disease each year.1 Children under 5 years are susceptible to ETEC, particularly in endemic areas, which was responsible for an estimated 100 million diarrhea episodes and 60,000 deaths in 2015.1,2 ETEC is also the key etiology for traveler’s diarrhea that affects travelers visiting low-income regions of the world, and approximately one-third of all traveler’s diarrhea patients seeking medical care were diagnosed with gastrointestinal disturbance.3 ETEC infection is caused by ingestion of contaminated food and water in developing countries, where lack the infrastructure to supply clean drinking water and disposal of excrement. Previous study has shown that ETEC can survive in feces for more than half a year, and generally occur in water in the form of biofilms which provides a greater potential to survive.4 (Figure 1) In low-income regions, infrastructure and sanitation associated to people’s health are difficult to dramatically improve in a short period of time, the risk of diarrhea caused by ETEC is hard to be effectively controlled.
Phosphodiesterase 5 (PDE5) restricts intracellular cGMP accumulation during enterotoxigenic Escherichia coli infection
Published in Gut Microbes, 2020
Jennifer Foulke-Abel, Huimin Yu, Laxmi Sunuwar, Ruxian Lin, James M. Fleckenstein, James B. Kaper, Mark Donowitz
The Global Enteric Multi-Center Study (GEMS) identified enterotoxigenic Escherichia coli (ETEC) infection as one of the four leading causes of acute diarrhea and associated mortalities in developing countries.1 As the leading cause of traveler’s diarrhea, ETEC is also a recognized burden on deployed U.S. military personnel.2 The host diarrheal response is initiated by the secreted peptide heat-stable enterotoxin (ST) and/or the multi-subunit protein heat-labile enterotoxin (LT) via induction of second messenger cGMP and cAMP synthesis, respectively. ETEC strain H10407, originally isolated from a patient in Bangladesh with severe cholera-like diarrhea,3 employs additional factors to facilitate host interaction, including but not limited to the secreted mucinase EatA4 and surface adhesins EtpA5,6 and CfaE.7 Strains expressing ST, alone or in combination with LT, were more highly associated with diarrhea than LT-only expressing strains,8 confirming the importance of ST in disease pathogenesis. As such, recent renewed efforts to employ ST antigens for vaccine development are under way.9,10
A bovine lactoferricin-lactoferrampin-encoding Lactobacillus reuteri CO21 regulates the intestinal mucosal immunity and enhances the protection of piglets against enterotoxigenic Escherichia coli K88 challenge
Published in Gut Microbes, 2021
Weichun Xie, Liying Song, Xueying Wang, Yigang Xu, Zengsu Liu, Dongfang Zhao, Shubo Wang, Xiaolong Fan, Zhaorui Wang, Chong Gao, Xiaona Wang, Li Wang, Xinyuan Qiao, Han Zhou, Wen Cui, Yanping Jiang, Yijing Li, Lijie Tang
Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrhea in man and animal. ETEC infections are the leading cause of travelers’ diarrhea and a major cause of diarrhea in developing nations, where it can be life-threatening among children.1,2 Gut microbes play important roles in host health and disease throughout life, particularly in infancy. The colonization of intestinal flora in infancy is a critical period for the formation of intestinal flora, which will affect the future growth and health of the body.3 The beneficial intestinal microflora not only helps in the digestion of food compounds but also reduces the potential of pathogen colonization in the guts.4 Many researchers have demonstrated that early intervention with desirable probiotics may help to establish a stable bacterial ecology and improve immunological development in the early life of human and animals.5 However, an important factor to consider is that probiotic properties are strain dependent, and it is not common to find microorganisms with multiple probiotic properties.6 Thus, using lactic acid bacteria (LAB) to produce the desired protein has become a new focus of research.7,8
Related Knowledge Centers
- Escherichia Coli
- Diarrhea
- Travelers' Diarrhea
- Pathogen
- Bacteria
- Enterotoxin
- Pilus
- Heat-Labile Enterotoxin Family
- Heat-Stable Enterotoxin
- Sanitation