Preface

The title of the book "The Universe of *Escherichia coli*" aims to present and emphasize the huge diversity of this bacterial species and our efforts to prevent the infections caused by *E. coli*. *E. coli* is on one hand a well-known commensal species, as it is part of the gut microbiota of humans and other warm blooded organisms. Probiotic strains of *E. coli* do exist and they are successfully used for improving host's health. Also many "workhorse" *E. coli* strain exist that are employed in laboratory and biotechnology settings. But on the other hand, *E. coli* is on the list of biological agents – it is grouped in the human pathogen hazard group 2 and some *E. coli* strains (enterohemorrhagic strains) even in the hazard group 3. Furthermore, *E. coli* belongs to the bacterial pathogens with the broadest disease spectrum, as it can cause intestinal and also extraintestinal infections at many anatomical sites. And *E. coli* is also known to be an important animal pathogen. Therefore many efforts are undertaken to prevent *E. coli* infections, among them food safety, vaccines, but also new alternative antimicrobial agents are searched for.

Hence the book has two sections, one dealing with the versatility of *E. coli* and the second dealing with our efforts to prevent *E. coli* infections. For both sections chapters were selected to represent the main topics.

Laboratory *E. coli* strains are categorized as non-pathogenic strains that can be safely used. So *E. coli* is a well-known and much used laboratory "workhorse", used as a model organism in many basic research areas. But *E. coli* is used also in biotechnology, where it is due to its rapid growth and easy handling, a much appreciated host organism, so many recombinant proteins are made by *E. coli* (see Chapter 1). Pathogenic *E. coli* strains are very diverse and associated with many types of infections in humans and animals. Among them a very prominent group are the enteropathogenic *E. coli*, which have been associated with outbreaks of diarrhoea (see Chapter 2). The versatility of *E. coli* is presented also by a large number of different mobile genetic elements such as transposons, plasmids, and insertion sequences that contribute to the plasticity of *E. coli* genome (see Chapter 3).

As *E. coli* is a well-known pathogen that becomes more and more resistant to antibiotics, we are already faced with difficulties in treatment of some *E. coli* infections, namely infections caused by the extended-spectrum beta-lactamases producing and carbapenem resistant *E. coli*. In this light, preventing *E. coli* infections by different means gains on importance. As humans can be infected by ingestion and/or not proper handling of with pathogenic *E. coli* contaminated food, special care has to be devoted to food safety and hence there is a chapter in the book dealing with this topic (see Chapter 4). As vaccines are a mean of possible protection against pathogenic *E. coli* that is not depending on the antimicrobial resistance pattern, a special chapter in the book is dealing with human and veterinary vaccines against pathogenic *E. coli* (see Chapter 7). WHO has put *Enterobacteriaceae* and among them *E. coli* on the list of bacteria for which new antimicrobial agents are urgently needed and grouped them into the Priority 1: CRITICAL group. So, in the last chapter the possibilities of photodynamic inactivation of *E. coli* with cationic porphyrin sensitizers are presented (see Chapter 8).

To conclude, I do hope that these selected chapters, even though small in number, do represent the extent of *E. coli* universe and my sincere thanks go to all the authors from many countries, which contributed these chapters. I also want to express my thanks to InTech, who gave the opportunity of publishing this book and to all the staff at InTech who helped in the process of making this book seeing the light.

> **Prof. dr. Marjanca Starčič Erjavec** Department of Biology, Biotechnical Faculty, University of Ljubljana, Slovenia

> > **1**

Section 1

Introduction

Section 1 Introduction

**3**

**Figure 1.**

*1932 to December 31, 2018 [1].*

**Chapter 1**

**1. Introduction**

Introductory Chapter: The

There are not so many organisms that are so well studied and researched as the bacterium *Escherichia coli* (*E. coli*). Since its discovery in 1885, it was used in research, and by end of 2018, there are now already 368,071 publications in PubMed about *E. coli* [1]. **Figure 1**, presenting data about number of publications found in PubMed for the search term "*Escherichia coli*" in the time frame from 1932 to 2018, clearly demonstrates the high and still growing research interest in this microbe.

The bacterium *E. coli* was discovered by the German-Austrian pediatrician Dr. Theodor Escherich (1857–1911) in 1885 [2]. He conducted examinations of neonate's meconium and feces of breast-fed infants with the aim to gain insight into the development of intestinal "flora." In preparations of meconium and stool samples under the microscope, he observed "slender short rods" of the size of 1–5 μm in length and 0.3–0.4 μm in width, which he named *Bacterium coli commune* (**Figure 2**). Further, he cultured these bacteria on agar and blood serum plates, where these bacteria grew as white, non-liquefying colonies. He also showed that these bacteria slowly cause milk to be clotted, as a result of acid formation, and

*Number of publications in PubMed for the search term "Escherichia coli" in the time frame from January 01,* 

Versatile *Escherichia coli*

*Marjanca Starčič Erjavec*

**2. The discovery of** *Escherichia coli*
