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).
In addition to its traditional clinical manifestations, GAS can also cause serious invasive disease such as necrotizing fasciitis, colloquially known as the flesh-eating disease. First broadly reported during the Civil War, when it was known as gangrene, necrotizing fasciitis occurs when an individual’s subcutaneous fat and superficial fascia become rapidly necrotic. Though incidence data is limited, one study estimated that, worldwide, there are approximately 660,000 cases of invasive GAS disease per year, with 97% of those cases occurring in low-income populations (4). Many microorganisms other than GAS have been linked with necrotizing fasciitis, including Staphyloccocus aureus, Escherichica coli, and Klebsiella pneumoniae, and the disease is often caused by a polymicrobial infection. However, the most well known causative agent in necrotizing fasciitis cases is usually Group A streptococci (6). Although risk factors for necrotizing fasciitis include diabetes, old age, and immunosuppression, nearly half of all infections occur i...
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...ly 24 hours postinfection, during the late exponential and early stationary phases, SpeB is dramatically upregulated as tissue invasion occurs and the bacteria disseminate (13). It is speculated that this upregulation occurs so that SpeB can cleave the GAS adhesive molecules and allow the bacteria to spread throughout the tissue during invasive infections (20). Following the dissemination of GAS in this stage, SpeB expression is once again downregulated as the bacterium invades the bloodstream. GAS selects for mutations in the CovRS regulatory system, which result in reduced expression of SpeB and a simultaneous enhancement of the production of another virulence factor, Sda1. Sda1 helps avoid host neutrophil extracellular traps, allowing the bacterium to survive in the bloodstream and produce the bacteremia and sepsis characteristic of invasive GAS infections (26).
In this lab project, the microbiology students were given 2 unknown bacteria in a mixed broth each broth being numbered. The goal of this project is to determine the species of bacteria in the broth. They had to separate and isolate the bacteria from the mixed broth and ran numerous tests to identify the unknown bacteria. The significance of identifying an unknown bacteria is in a clinical setting. Determining the exact bacteria in order to prescribe the right treatment for the patient. This project is significant for a microbiology students because it gives necessary skills to them for future careers relating to clinical and research work.
Hospital-acquired infections (HAI) are preventable and pose a threat to hospitals and patients; increasing the cost, nominally and physically, for both. Pneumonia makes up approximately 15% of all HAI and is the leading cause of nosocomial deaths. Pneumonia is most frequently caused by bacterial microorganisms reaching the lungs by way of aspiration, inhalation or the hematogenous spread of a primary infection. There are two categories of Hospital-Acquired Pneumonia (HAP); Health-Care Associated Pneumonia (HCAP) and Ventilator-associated pneumonia (VAP).
Also contributing to the virulence of the bacteria are the exotoxins including invasive adenylate cyclase, tracheal cytotoxin, and lethal toxin. Invasive adenylate cyclase reduces local phagocytic activity as well as acting as a hemolysin. Tracheal toxin affects the ciliated respiratory epithelium by inhibiting the ciliary beating. This kills the cells and causes them to be eliminated from the mucosa. Tracheal toxin also stimulates the release of IL-1, which causes fever. Lastly, lethal toxin causes inflammation and local necrosis at infection sites.
Studies have shown pertactin, a 69kDa non fimbrial outer membrane protein, facilitates attachment of the bacteria to ciliated respiratory cells. Experiments conducted on humans to test the role of pertactin have shown no significant effect except with the results from Bassinet (4). Furthermore, filamentous haemagglutinin confers infection by attaching to the host cells in the lower respiratory tract. It is about 2nm wide, and 50n...
It is not unusual for some healthy women to harbor Group B streptococcus bacteria in their rectum and vagina. These microorganisms do not usually cause disease when few in number, but when they grow in number and colonize these areas, bacterial infection can become severe.
My disease is Streptococcal pneumonia or pneumonia is caused by the pathogen Streptococcus pneumoniae. Streptococcus pneumoniae is present in human’s normal flora, which normally doesn’t cause any problems or diseases. Sometimes though when the numbers get too low it can cause diseases or upper respiratory tract problems or infections (Todar, 2008-2012). Pneumonia caused by this pathogen has four stages. The first one is where the lungs fill with fluid. The second stage causes neutrophils and red blood cells to come to the area which are attracted by the pathogen. The third stage has the neutrophils stuffed into the alveoli in the lungs causing little bacteria to be left over. The fourth stage of this disease the remaining residue in the lungs are take out by the macrophages. Aside from these steps pneumonia follows, if the disease should persist further, it can get into the blood causing a systemic reaction resulting in the whole body being affected (Ballough). Some signs and symptoms of this disease are, “fever, malaise, cough, pleuritic chest pain, purulent or blood-tinged sputum” (Henry, 2013). Streptococcal pneumonia is spread through person-to-person contact through aerosol droplets affecting the respiratory tract causing it to get into the human body (Henry, 2013).
With the earliest recordings coming from the Fifth Century B.C., streptococcus pyogenes, and more frequently, its symptoms have been prevalent among doctors and historians for hundreds of years. The first mentioning of streptococcus pyogenes is to be credited to Hippocrates, in which he describes the relative symptoms of the flesh-eating bacteria in its early stages. Then depicted by Billroth in 1874, patients carrying erysipelas were determined to have this certain bacterial infection. In 1883, the chain-forming bacteria were isolated by Fehleisen; and in the following year, Rosenbach applied the S. pyogenes name. Further advances in hemolytic and non-hemolytic studies were made by Lancefield in the 1930’s, in which the alpha, beta, and gamma subgroups of the hemolytic structures – detailed and defined by Schottmueller and Brown - were divided into serotypes.
Capriotti & Frizzell (2016) explain that sepsis is often seen in those who have a weak immune system. These individuals are at an increased risk of developing sepsis from microorganisms that a healthy immune system would normally fight off (Capriotti et al. 2016). The elderly, infants, and immunosuppressed patients are the most at risk for developing the condition (Capriotti et al. 2016). Sepsis can be caused by any microbe, but is most often caused by bacteria (Capriotti et al. 2016). Since sepsis has such a broad reach and can develop as a secondary infection after an initial injury or illness, Capriotti & Frizzell (2016) further explain the di...
(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.
Necrotizing Fasciitis (flesh eating bacteria ) from an essay by Katrina Tram Duong, edited by S.N. Carson M.D.
Rheumatic fever is a disease that can occur following bacterial infection with Group A Streptococcus. Predisposing infections also include strep throat tonsillitis and skin infections, such as impetigo, caused by Streptococcus pyogenes. Overall, rheumatic fever is rare in Australia; however, the rate of rheumatic fever amongst Indigenous Australians is much higher. Rheumatic fever is a serious condition that can lead to long-term complications, such as rheumatic heart disease.
Sepsis is defined as an exaggerated, overwhelming and uncontrolled systemic inflammatory response to an initially localised infection or tissue injury, which may lead to severe sepsis and septic shock if left untreated (Daniels, 2009; Robson & Daniels, 2013; Dellinger et al, 2013; Perman, Goyal & Gaieski, 2012; Vanzant & Schmelzer, 2011). Septic shock can be classified by acute circulatory failure as a result of massive vasodilation, increased capillary permeability and decreased vascular resistance in the body, causing refractory hypotension despite adequate fluid resuscitation. This leads to irreversible tissue ischaemia, end organ failure and ultimately, death (McClelland & Moxon, 2014; Sagy, Al-Qaqaa & Kim, 2013, Dellinger et al, 2013).
our everyday lives bacteria is constantly surrounding us, some of the bacterium that we encounter are beneficial to us but then there are the ones that are severely detrimental to our health. The way that they effect a persons body can differ from person to person. Many of the “microscopic foes” are very resilient and have a very fast reproduction rate. Not only do they reproduce quickly they sometimes seem to outsmart our immune system and not allow our bodies to fight the infection making it almost impossible to stop them. One thing that a lot if people rely on is the assistance of prescription drugs to get them better but even the drugs are not being effective and we can’t stop the pathogens from invading our personal places such as work, home, school, or anywhere. Even though modern medicine is advancing the pathogens could still get the get the best of us. The scary thing is we never know when the next pandemic or epidemic is going to arise. All it needs is some ordinary microbe to swap genes with a deadly germ to produce a “super pathogen” and it could happen to anyone, anywhere, as it did to Jeannie Brown who is from “our neck of the woods”.
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
One of the most popular tonsil infections is ‘tonsillitis’ which is caused by both bacterial and viral pathogens. According to Simon (81), the inflammation of tonsils by streptococci bacteria causes swellings and reddening of the tonsils. Since this infection is mostly associated with young teens and children, it has been a major cause of school absenteeism among school-aged children since the throat becomes hypersensitive to any solid materials. Quite importantly, swallowing of materials from the mouth becomes a major problem among the victims of ‘tonsillitis’ (Burton 39). Notably, tonsillitis has been revealed to reoccur in most cases, necessitating surgical operations to remove them. However, great care should be taken while removing the tonsils since in cases of poor operations; severe complications are usually experienced by the victims of the infection...