Bordetella Pertussis free essay sample

In 1906 two Belgian bacteriologists, Jules Bordet and Octave Gengou first discovered Bordetella pertussis, what is known today as the whooping cough, by isolating it in pure culture. They distinguished the whopping cough agent from the respiratory tract of children (Jules Bordet). B. pertussis is a very small, prokaryotic, coccoid bacterium, which does not make endospores. It is a gram negative bacterium which means the cell structure contains an outer membrane, an inner membrane, and a thin peptidoglycan layer. It metabolizes through aerobic respiration, is nonmotile and an encapsulated microorganism. It appears either in pairs or singly, cannot survive in the environment and only reside in human hosts, where it usually appears in the trachea and the bronchi. B. pertussis produces several virulence factors. These include pertussis toxin, which is secreted in the cell and extracellular fluid, and filamentous hemagglutinin, which is a â€Å"fimbrial-like structure on the bacterial surface† (Todar). B. pertussis is nutritionally fastidious meaning it has complex growing requirements, and is difficult to grow without specialized media. We will write a custom essay sample on Bordetella Pertussis or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page It requires special growth factors and may not grow on routine media, although it has been found that the organism grows better on a media that has a slightly acidic pH. Growth of this organism is restrained by its own waste as well as heavy metals, peroxides, sulfides, and fatty acids. To neutralize any inhibitory substances and absorb toxic metabolites this organism is often grown on media with rich concentrations of blood, or charcoal. (Pertussis. ). Two different solid cultures that are used in growing B. pertussis are Bordet-Gengou agar (BGA) and Regan-Lowe agar (RLA). Bordet- Gengou agar contains potato starch and is peptone free, also an inhibitory substance. It also contains glycerol as a stabilizer, and an antibiotic, such as penicillin, to restrain gram positive organisms from growing, although the antibiotic may slightly restrain B. pertussis itself. Another method of growing B. pertussis is on Regan-Lowe agar. This agar is a charcoal based solid with defibrinated horse blood. (Ahmad). The charcoal helps absorb waste products and toxins. This charcoal agar has become more popular in laboratories because, â€Å"of the ease of its preparation and its superiority in growing B. ertussis by absorbing the toxic metabolites of the organism† (Ahmad 1071). B. pertussis grows quite slowly and it best grows when it is incubated at 35 ° to 37 ° C in a humid or moist environment for about 3 to 6 days. It grows as a mercury colored droplets with domed colonies. B. pertussis is a worldwide occurrence that causes a highly contagious acute infectio us disease called â€Å"whooping cough† which resides in the upper air pathways such as the bronchi and trachea, and appears on epithelial cilia of respiratory tract. A â€Å"whoop† is a â€Å"high-pitched noise heard when breathing in after a coughing spasm† (CDC). The first outbreaks were described in the 16th century but it was not until 1906 that it was discovered. it is a much more milder disease in adults than it is in infants, in which it can be very severe and frequent, and it was not until the 1930’s that immunization was discovered. B. pertussis is contracted through aerosol droplets from person to person, which are either sneezed or coughed in the air by the infected person. The bacteria then â€Å"attaches to the cilia of the respiratory epithelial cells, produce toxins that paralyze the cilia, and cause inflammation of the respiratory tract, which interferes with the clearing of pulmonary secretions† (Pertussis). After seven to ten days of the incubation period of the bacteria the first stage of the infection appears. This stage lasts anywhere from one to two weeks and is called the catarrhal phase. In this phase the infected person experiences cold like symptoms such as runny nose, fever, mild cough, and sneezing. After about another week or so the cough slowly becomes more severe and the second phase of the disease presumes: the paroxysmal phase. Only during this phase can the diagnosis of whooping cough actually be claimed. The cough appears at various intervals where one may become cyanotic, turn blue, and may result in vomiting due to mucus buildup on the tracheobronchial tree. If the cough is long enough an infant may go into hypoxia, which is a state where there is a reduced amount of oxygen, and further lead to seizure. In result other symptoms include dehydration, weight loss, and potentially anorexia. The last phase is called the convalescent phase meaning gradual recovery phase. The cough becomes less severe and disappears within a few weeks. (Pertussis ). â€Å"In 2004 through 2008 a total of 111 deaths from pertussis were reported to the CDC†. ( Pertussis). Pertussis toxin is an exotoxin that is produced during the infection and is the major cause of the abnormal cough. It causes T cell lymphocytosis, increased IgE synthesis, hyperglycemia, increased endotoxin sensitivity, and impairs NK cell killing. This results in the accumulation of large amounts of cAMP which leads to increased mucus secretion and interferes with many cellular functions† (Ghaffer). Other virulence factors include filamentous hemagglutinin, pertactin, and fimbriae. These are adhesions that allow the bacterium to attach to the glycolipids on the membrane of ciliated epithelial cells of the respiratory cells. (CD C). Precautions to take in order to prevent pertussis are getting vaccinated, as early as 6 weeks old, with the diphtheria-tetanus-pertussis vaccine, good hygiene, and covering the mouth when sneezing or coughing. Antibiotics are used to treat the disease. In 2010, 27,550 cases of whooping cough in the United States have been reported to the CDC. Worldwide there are up to 50 million cases and over 300,000 deaths that have been reported. Whooping cough may not sound like a severe disease but if people go untreated and unvaccinated, especially people in less developed countries, it could become fatal, especially to infants and younger children, whose immune systems are not as strong. Therefore, it is important that as many people are aware of this disease and do not go unvaccinated or untreated.