Bacterial infections can occur in almost every part of the human body, which indicates that bacteria have adapted to survive in physiologically distinct anatomical locations” Young et al (2016).
“Bacterial infections can occur in almost every part of the human body, which indicates that bacteria have adapted to survive in physiologically distinct anatomical locations. To facilitate this process, an organism must express the proper growth and virulence factors at the appropriate time, endure a potentially harsh surrounding chemical environment, and thwart a host’s immune defenses.
Several bacterial species use structures referred to as biofilms to combat these hazards. A bacterial biofilm is defined as a sessile community of organisms encased in a matrix of extrapolymeric substances and attached to a substratum, interface, or to each other. Biofilms tend to exhibit an altered phenotype with respect to growth rate and gene transcription (Donlan & Costerton, 2002). The development of biofilms can be described by a five-stage process (Sauer, Camper, Ehrlich, Costerton, & Davies, 2002; Stoodley, Sauer, Davies, & Costerton, 2002). Briefly, Stage 1 consists of planktonic cells transiently adhering to a surface. At this stage, only small amounts of extrapolymeric components are associated with the attached cells and many cells are still capable of independent movement (O’Toole & Kolter, 1998). During Stage 2, cells begin to produce larger amounts of extracellular polymer, which leads to a more stable attachment. Stages 3 and 4 involve the establishment and maturation of biofilm architecture. Cell clusters interspersed with water channels form three-dimensional structures that are widely recognized today as microcolonies, and cells within these microcolonies begin to alter their physiology. Stage 5 is associated with the dispersal of individual cells or pockets of cells from the biofilm structure. These cells are free to disseminate, recolonize, and repeat the cycle of biofilm development. In Streptococcus pyogenes, a mature biofilm is known to consist of proteins, DNA, and a polysaccharide-containing material known as glycocalyx (Doern, et al., 2009; Akiyama, Morizane, Yamasaki, Oono, & Iwatsuki, 2003; Cho & Caparon, 2005). (Figure 1) Biofilms are responsible for a large medical burden throughout the world. According to the US National Institute of Health, biofilms account for over 80% of microbial infections in the human body (Davies, 2003). An estimated 17 million new biofilm infections arise annually in the United States, which result in as many as 550,000 fatalities each year (Worthington, Richards, & Melander, 2012) and cause an ever-growing economic burden, due to chronic infections and longer hospital stays. Biofilms pose a significant health risk because they are inherently tolerant to host defenses and are up to a thousand times more resistant to conventional antibiotics (Rasmussen & Givskov, 2006). Additionally, biofilms formed within medical devices such as prosthetic heart valves, intrauterine devices, central venous catheters, and urinary catheters can be very difficult to eliminate. Their removal requires the use of aggressive antibiotic therapies, surgical debridement, and removal of the infected device (Donlan & Costerton, 2002; Stewart & Costerton, 2001). Biofilm-residing bacteria, including S. pyogenes, are able to persist on both biotic and abiotic surfaces (including soft toys, books, cribs, and other hard surfaces) for extended periods of time. This results in an increased chance of exposure from contact with surfaces that were previously disregarded as a source of transmission (Marks, Reddinger, & Hakansson, 2014a)” Young et al (2016).
Young, C., Holder, R.C., Dubois, L. and Reid, S.D. (2016) Streptococcus pyogenes Biofilm. Cited in: Ferretti, J.J., Stevens, D.L., Fischetti, V.A. (2016) Streptococcus pyogenes: Basic Biology to Clinical Manifestations . Oklahoma City (OK): University of Oklahoma Health Sciences Center.
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