Streptococcus pyogenes is a microorganism from the kingdom of bacteria that is considered to be a unique and extremely complex opportunistic pathogen. The bacterium is especially unique because it has the ability to cause several diseases, ranging from mild to severe outcomes. Streptococcus pyogenes is named so because strepto means chains, coccus is used to describe a spherical shape, and pyogenes is used to describe a pus-forming organism. “S. pyogenes is considered one of the most frequent pathogens in humans and can be found on the skin or in the respiratory tract of 5-15% of the population, without causing disease” (Todar, 2002). Although the bacteria is often carried non-symptomatically by many people, it has potential to cause life-threatening invasive diseases in cases where it reaches the deep tissue, such as streptococcal toxic shock syndrome and type II necrotizing fasciitis, also known as the flesh-eating disease. Invasive streptococci infections also include joint or bone infections, destructive wound infections, myositis, meningitis, and endocarditis (Todar, 2002). Noninvasive forms include pharyngitis (strept throat), scarlet fever, cellulitis and impetigo (superficial skin infection also known as pyoderma). Since the noninvasive forms are common, predictable, and fairly easy to treat, this paper will discuss the rare invasive and often, fatal forms disease caused by S. pyogenes, specifically necrotizing fasciitis.
Causal Agent
S. pyogenes is a gram-positive, non-motile, non-sporeforming coccus that exist in chains or pairs of cells (Todar, 2002) and are negative for oxidase and catalase (Khan, 2013). Individual cells are round-to-ovoid n shape, and 0.6-1.0 micrometer in diameter. S. pyones is an aerotolerant anaer...
... middle of paper ...
...erica, 12(2), 181-186.
Sharkawy A, Low DE, Saginur R, et al. Severe group A streptococcal soft tissue infections in Ontario: 1992-1996. CID 2002;34:454-60.
Steer AC, Lamagni T, Curtis N, Carapetis JR. (2012) Invasive group a streptococcal disease: epidemiology, pathogenesis and management. Drugs. 2012;72(9):1213-27. http://dx.doi.org/10.2165/11634180-000000000-00000. PMid:22686614.
Todar, Ken. 2002. "Streptococcus pyogenes"
Tortora G, Funke B, Case C. 2007. Microbiology: An Introduction, 9th Edition. Pearson Education, Inc.
Trent, J. Kirsner, R. (2002). Necrotizing Fasciitis-Wounds. http://www.medscape.com/viewarticle/444061_4
Wong CH, Chang HC, Pasupathy S, Khin LW, Tan JL, Low CO. Necrotising fasciitis; clinical presentation, microbiology, and determinants of mortality. J Bone Joint Am 2003; 85 – A:1454
The Gram positive bacteria has been nicknamed Posi. The Gram positive species’ morphology includes having an opaque opacity with a smooth margin. The moisture content of the Gram positive species is shiny and the pigmentation is gold. The Gram positive species grows at an optimal temperature of 37°C. The shape of the Gram positive species is a cocci, with an arrangement of grapelike clusters. The Gram positive species’ size ranges from .5-1.5 µm. Oxygen requirement of the Gram positive species is facultative, and has complete lysis of red blood cells. All results are summarized in Table
The purpose of this study is to identify an unknown bacterium from a mixed culture, by conducting different biochemical tests. Bacteria are an integral part of our ecosystem. They can be found anywhere and identifying them becomes crucial to understanding their characteristics and their effects on other living things, especially humans. Biochemical testing helps us identify the microorganism present with great accuracy. The tests used in this experiment are rudimentary but are fundamental starting points for tests used in medical labs and helps students attain a better understanding of how tests are conducted in a real lab setting. The first step in this process is to use gram-staining technique to narrow down the unknown bacteria into one of the two big domains; gram-negative and gram-positive. Once the gram type is identified, biochemical tests are conducted to narrow down the specific bacterial species. These biochemical tests are process of elimination that relies on the bacteria’s ability to breakdown certain kinds of food sources, their respiratory abilities and other biochemical conditions found in nature.
Pseudomonas aeruginosa (P. aeruginosa) is a gram-negative, rod-shaped aerobic bacterium. It is a primary cause of hospital-acquired infections. P. aeruginosa is primarily a nosocomial pathogen. It also acts as an opportunistic pathogen, which can only infect a host that is immunocompromised, due to an underlying disease or medication. Although, P. aeruginosa can cause damage to virtually any tissue in the body, it almost never affects the tissues of healthy individuals. It is a problematic pathogen in hospitals; infecting individuals with cancer, burn wound, catheters and cystic fibrosis. P. aeruginosa is most recognized for its resistance to a wide range of antibiotics. In its planktonic form, P. aeruginosa has been found to have many virulence factors. However, P. aeruginosa within biofilms have been found to have a resistance to antibiotics 1,000 times greater than that of its planktonic counterparts [4]. Infections that are caused by bacterial biofilms are very persistent and very difficult to treat.
Streptococcus pyogenes, also known as Group A streptococcus (GAS), is a β-hemolytic, Gram-positive bacterium that most commonly causes respiratory disease, including pharyngitis or tonsillitis, as well as skin infections such as impetigo and cellulitis. The organism is transmitted via respiratory droplets or by contact with fomites, and commonly infects young children. In addition to the common clinical presentations associated with S. pyogenes, some individuals develop the postinfectious sequelae of rheumatic fever and glomerulonephritis. Due to the severity of these medical consequences, prophylactic antibiotic use is often recommended for any patients with otherwise mild S. pyogenes infections (21).
Plantar fasciitis is caused from muscles and ligaments that alter the calcaneous (the big bone on hill of foot) (Daniels and Morrell 2012). The alteration of these muscles and ligaments will inflict pain and discomfort on the patient, and if not treated will cause failure of ligaments, bones, and muscles. The patient was tested with a simple squat technique that showed his heels were coming off the ground (Daniels and M...
mutans was problematic due to its difference with Bergey’s Manual result for the catalase test. However, after comparing it with a peers results, it seems very possible that the strain we are working with varies from the strain used in Bergey’s. Bacteria possess the ability to develop varying phenotypes within the same species due to frequent mutation and horizontal gene transfer. Therefore, it is possible that the results obtained in our lab may vary from those provided in Bergey’s Manual. Arriving to the conclusion that the Gram negative bacteria was Klebsiella pneumoniae was much more direct. Using Bergey’s Flowchart for identification, the bacteria shared the test results and had a similar shape and
This pathogen, Streptococcus pneumoniae, is a gram-positive coccus that is long shaped and usually seen in groups of pairs (Todar, 2008-2012). This pathogen ranges from o.5-1.25 micrometers, which is pretty small in size (Todar, 2008-2012). It “lacks catalase and ferments glucose into lactic acid” (Todar, 2008-2012). To grow this bacterium in the lab the best way to do it would be to grow it on a blood agar at 37 degrees Celsius and produces a green zone arou...
Being a gram-negative bacterium, L. pneumophila has lipopolysaccharides (LPS) that act as endotoxin within a human host. The presence of a flagella is thought to mediate adherence to human lung cells, thereby causing infection, since flagella-less strains do not cause disease. Once attached to human cells, the organism is engulfed by a macrophage where is utilizes the internal environment to multiply.
(Nemours, 1995-2011) The two main bacteria precipitating Impetigo are staphylococcus aureus, the most common cause, and streptococcus pyogenes. If left untreated, streptococcus pyogenes can also cause post-streptococcal glumerulonephritis, or a disease that causes inflammation of the kidney to occur following a strep throat infection. Although this is rare, standard precautions must still be taken to prevent these repercussions. Staphylococcus aureus and streptococcus pyogenes are the main causes of impetigo, but they are not the only.
Pathophysiology of infection, inflammation response, and sepsis leading to septic shock (the cascade) is a major area of interest in the literature. Under normal circumstances, when a pathogen enters a human host and tissue damage occurs, the host initiates an inflammatory response to repair the tissue. The main types of pathogens include viruses, bacteria, and parasites (Porth & Matfin, 2009; Raghavan & Marik, 2006). Cellulitis is an example of an acute infection, which affects the skin and or subcutaneous tissue often in lower limbs. Cellulitis is caused by streptococcus pyogenes and staphylococcus aureus (multi-resistant bacteria) and is transmitted by direct contact, entering the body via broken skin such as ulcers and or following trauma. The presentation of cellulitis often includes pain (localised), erythema, fever and swelling. Infections such as cellulitis have a propensity to become systemic through distribution in the blood and lymph (Hadzovic-Cengic et al., 2012). The inflammation response to an infection involves the release of both pro and anti-inflammatory mediators. When excessive pro-inflammatory mediators such as cytokines are released they cause inflammation in a systemic manner that can cause sepsis or systemic inflammatory response syndrome (being the non-specific response to non-infectious cause) (Sagy, Al-Qaqaa, & Kim, 2013). Pro-inflammatory mediators also activate the complement system, which results in increased inflammation and upregulation of specific receptors that lead to cellular injury and apoptosis seen in severe sepsis and organ dysfunction (Ward, 2008). Organ dysfunction can occur in one or more organs such as the lungs, liver, kidneys and or heart and often results from a lack of...
Necrotizing fasciitis is caused most commonly by Streptococcus pyogenes, group A streptococcus, which is the same bacteria that causes common strep throat 8.
Cellulitis is an infection that also involves the skin's deeper layers: the dermis and subcutaneous tissue. The main bacteria responsible for cellulitis are Streptococcus and Staphylococcus ("staph"). MRSA (methicillin-resistant Staph aureus) can also cause cellulitis. Sometimes, other bacteria (for example, Haemophilus influenzae, Pneumococcus, and Clostridium species) may cause cellulitis as well. Cellulitis is fairly common and affects people of all races and ages. Men and women appear to be equally affected. Although cellulitis can occur in people of any age, it is most common in middle-aged and elderly
After Bryant Hatch lost his leg to MRSA, which is a contagious and antibiotic- resistant staph bacteria that leads to potentially dangerous infection, his son and son in law discover some useful information. Both his sons were interested in microbiology. Brad Berges was a virologist and Jacob Hatch was a senior molecular biology student at the time in BYU. MRSA is usually picked up in the hospital by already-immunocompromised people like Bryant Hatch, who has struggled with foot problems and surgeries due to his diabetes. MRSA grows together into clusters creating a biofilm that is resistant to penetration by most known antibiotics. MRSA secretes white blood cell killing molecules, neutralizes your antibodies and trigger your immune system
Streptococcus pyogenes is thought to live benignly within one in five people, and is thusly one of the most common pathogens among humans. Due to its common
Bacterial cells, like plant cells, are surrounded by a cell wall. However, bacterial cell walls are made up of polysaccharide chains linked to amino acids, while plant cell walls are made up of cellulose, which contains no amino acids. Many bacteria secrete a slimy capsule around the outside of the cell wall. The capsule provides additional protection for the cell. Many of the bacteria that cause diseases in animals are surrounded by a capsule. The capsule prevents the white blood cells and antibodies from destroying the invading bacterium. Inside the capsule and the cell wall is the cell membrane. In aerobic bacteria, the reactions of cellular respiration take place on fingerlike infoldings of the cell membrane. Ribosomes are scattered throughout the cytoplasm, and the DNA is generally found in the center of the cell. Many bacilli and spirilla have flagella, which are used for locomotion in water. A few types of bacteria that lack flagella move by gliding on a surface. However, the mechanism of this gliding motion is unknown. Most bacteria are aerobic, they require free oxygen to carry on cellular respiration. Some bacteria, called facultatibe anaerobes can live in either the presence or absence of free oxygen. They obtain energy either by aerobic respiration when oxygen is present or by fermentation when oxygen is absent. Still other bacteria cannot live in the presence of oxygen. These are called obligate anaerobes. Such bacteria obtain energy only fermentation. Through fermentation, different groups of bacteria produce a wide variety of organic compounds. Besides ethyl alcohol and lactic acid, bacterial fermentation can produce acetic acid, acetone, butyl alcohol, glycol, butyric acid, propionic acid, and methane, the main component of natural gas. Most bacteria are heterotrophic bacteria are either saprophytes or parasites. Saprophytes feed on the remains of dead plants and animals, and ordinarily do not cause disease. They release digestive enzymes onto the organic matter. The enzymes breakdown the large food molecules into smaller molecules, which are absorbed by the bacterial cells. Parasites live on or in living organisms, and may cause disease. A few types of bacteria are Autotrophic, they can synthesize the organic nutrients they require from inorganic substances. Autotrophic bacteria are either photosynthetic or Chemosynthetic. The photosynthetic bacteria contain chlorophyll that are different from the plant chlorophyll. In bacterial photosynthesis, hydrogen is obtained by the splitting of compounds other than water.