Preface

I am greatly thankful to IntechOpen for inviting me to serve as editor of this book on *Pseudomonas aeruginosa - Biofilm Formation, Infections and Treatments*.

This book covers a wide array of subjects relevant to bacterial biofilms specifically focusing on *P. aeruginosa* and associated infections. The principal objective of this book is to provide readers with a clear and comprehensive overview of biofilm formation and its detrimental impacts. In addition, this book also examines topics related to biosynthesis virulence factors by *P. aeruginosa* to facilitate biofilm formation, antibiotic resistance mechanisms, and infections. Biofilms and associated infections have a huge impact on human health, livestock, agriculture, and the world's economy overall. Thus, it is of paramount importance for scientists, medical professionals, healthcare workers, and the public to gain knowledge on this recurring issue and do every bit to sustain biofilms and their damaging impacts.

*P. aeruginosa* is an opportunistic Gram-negative bacterium that easily thrives and survives in various biotic and abiotic environments. Colonization and establishment of this bacterium species as biofilms, especially in hospitals and other communal environments, leads to contamination of water and food and is the leading cause of healthcare-associated or nosocomial infections. *P. aeruginosa* is also the most common pathogen in patients with cystic fibrosis, urinary tract infection, and wounds. Its antibiotic resistance is a major cause of mortality and morbidity. Understanding the mechanisms by which *P. aeruginosa* establishes as biofilms, evades antibiotics and antiseptics, and triggers life-threatening infections in humans is very important. Research on *P. aeruginosa* has been in the limelight for many decades as evidenced by the hundreds of journals, conferences, and projects in this field. Published research papers, conferences, and opinions from expert scientists, clinicians, and healthcare workers in recent years have undoubtedly enhanced the scientific basis for *P. aeruginosa*-associated infections and treatments.

To this end, I would also like to express my gratitude to all the scientists and researchers from different research institutes and universities who put immense effort into writing their chapters for this book.

> **Theerthankar Das** Department of Infectious Diseases and Immunology, School of Medical Sciences, The University of Sydney, Sydney, Australia

**1**

as heartburn, acid-reflux [4, 5].

**Chapter 1**

Pathogens

*Theerthankar Das*

**1. Introduction**

Introductory Chapter:

by Opportunistic Bacterial

Understanding Infections Caused

Infectious diseases caused by virus, bacteria and fungi represent a major apprehension globally in terms of detrimental public health and economy. Some of the infectious agents such as virus (e.g., Coronavirus, influenza, Ebola, chickenpox), bacteria (e.g., tuberculosis, cholera, whooping cough) are highly contagious and are responsible for communicable diseases. Communicable diseases spread from person to person through close contact including touching and kissing, also via coughing and sneezing, contamination of food and water. Many bacteria are also opportunistic pathogens and are commonly cause mild–moderate infections including sore throat, acne, tooth decay, urinary tract infections, cellulitis/skin infection, sexually transmitted infection, bacterial vaginosis, peptic/stomach ulcer, keratitis/eye infection, to severe/life-threatening infections such as pneumoniae, septicaemia/sepsis, meningitides in humans, animals, and birds. Most opportunistic bacteria exist as a commensal flora within the host body (gastrointestinal tract, skin, mucosal, oral, and nasal cavity, urogenital tract) and commonly found in abiotic surfaces (water, food, soil) in the environment [1, 2]. Under normal conditions i.e., in healthy people these bacterial pathogens do not cause infections. Infections caused by opportunistic bacteria are primarily triggered by either invasion of host commensal bacteria or bacteria from environmental sources gets into host bodily tissue [1, 2]. However, these opportunistic bacteria primarily target and cause fatal infections in immunocompromised people including acquired immunodeficiency syndrome (AIDS/HIV positive) patients, cancer patients (treated with immunosuppressive drugs, corticosteroids), hospital admitted patients for surgery, patients with underlying diseases such as cystic fibrosis, diabetes [2]. Most common examples of opportunistic bacteria found in mammals, birds and environment are *Pseudomonas aeruginosa*, *Staphylococcus aureus*, *Staphylococcus epidermidis*, *Escherichia coli, Klebsiella pneumoniae, Neisseria meningitides,* 

*Acinetobacter baumannii, Helicobacter pylori*, *Streptococcus pneumoniae*, *Streptococcus pyogenes*, *Streptococcus mutans*, *Clostridioides difficile, Legionella pneumophila, Propionibacterium acnes*, etc. On the other hand, mammalian and bird's body also host different species of good bacterial species (probiotics) which are essential for general wellbeing [3]. Lactobacillus and Bifidobacteria species are the common example of probiotics bacteria that are present in the mammalian digestive tract, they aid in maintaining daily healthy lifestyle includes food digestion, balancing pH of the body, alleviate symptoms of Gastroesophageal reflux diseases (GERD) such
