Volume 3 • Issue 4 • 1000156 Clin Microbial ISSN: 2327-5073 CMO, an open access journal Research Article Open Access Moghaddam et al., Clin Microbial 2014, 3:4 http://dx.doi.org/10.4172/2327-5073.1000156 Review Article Open Access Clinical Microbiology: Open Access Quorum Sensing in Bacteria and a Glance on Pseudomonas aeruginosa Mehrdad Moosazadeh Moghaddam 1,2 *, Samaneh Khodi 1 and Ali Mirhosseini 1 1 Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran 2 National Institute of Genetic engineering and Biotechnology, Tehran, Iran Keywords: Quorum sensing; Pseudomonas aeruginosa; Autoinducer; Cell-to-Cell signaling Introduction Pseudomonas aeruginosa is an opportunistic pathogen that primarily infects patients with immune deiciency such as neutropenia. Generally, the pathogenesis of Pseudomonas is complex and multifactorial, since the bacterium is both invasive and toxigenic, can cause a range of infections in humans (Table 1) [1-3]. Pseudomonas clearance is oten challenging due to immunodeiciency in patients with infection, multidrug resistancy and sometimes β-lactamase production and the inactivation of third-generation cephalosporin [4,5]. P. aeruginosa produces a variety of cellular structures and products involved in the ability to cause disease through enforcing the adhesion, protecting the phagocytosis, modifying the immune response or destroying the host tissue. Generally, the efective factors involved in the development of infection by this bacterium can be divided into two categories: Extracellular virulence factors and structural virulence factors. Extracellular factors include pigments that are active in Fe absorption, prevent the growth of other bacterial species and degrade factors including protease, hemolysins and toxins (Figure 1) [6,7]. Major structural factors in this bacterium are pili, lagellum and LPS. In addition to these factors, P. aeruginosa has also other capabilities that enhance bacteria pathogenesis, including a broad- spectrum Beta-Lactamase (ESBLs) of class A-B and D that is one of *Corresponding author: Mehrdad Moosazadeh Moghaddam, Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran, P.O. Box 19395-5487, Tel: +982182482549; E-mail: mm.genetics@gmail.com Received April 25, 2014; Accepted June 13, 2014; Published June 20, 2014 Citation: Moghaddam MM, Khodi S, Mirhosseini A (2014) Quorum Sensing in Bacteria and a Glance on Pseudomonas aeruginosa. Clin Microbial 3: 156. doi:10.4172/2327-5073.1000156 Copyright: © 2014 Moghaddam MM, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Quorum sensing is a key behaviour-coordination mechanism employed by many bacteria to regulate gene expression in accordance with population density through the use of signal molecules, known as autoinducers. The quorum sensing is used by Bacteria populations to communicate and coordinate their group interactions, which is typically applied by pathogens in infection processes. Generally, the quorum sensing pathways in bacteria are composed of several main parts, including bacteria populations, signal molecules, protein activators and target genes. In this system, the bacteria secrete the signal molecules into the environment and the concentration increases gradually as the bacteria population grows. In a certain concentration threshold, the molecules become detectable to the bacteria populations, and then activate target genes that regulate various behaviours, such as virulence factors. In Pseudomonas aeruginosa, the expression of many virulence factors appears to be controlled by quorum sensing. So, according to the role of this mechanism in the regulation and production of many virulence factors, the function of quorum sensing is required for Pseudomonas aeruginosa to cause disease and infection. In this article, we discussed the quorum sensing mechanism in Gram negative and positive bacteria with a closer look at the Pseudomonas aeruginosa. the major causes of high bacterial resistance to most commonly used antibiotics; an exopolysaccharid known as bioilm matrix and secreted Figure 1: Virulence factors in Pseudomonas aeruginosa. Infection Related Risk Factors Pneumonia Old age, Chronic obstructive pulmonary disease, Cystic ibrosis, Mechanical ventilation Bacteremia Immunocompromised Urinary tract Use of urinary catheter Soft tissue Burns, Open wounds, Postsurgery Diaberic foot Diabetes, Impaired microvascular circulation Keratitis Extended contact lens wear, Contaminated contact lens solution Otitis externa Tissue injury, Water blockage in ear canal Otitis media folliculitis Improperly cleaned hot tubs Table 1: Common infections causing by Pseudomonas aeruginosa [3].