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Epiglottis is the piece of cartilage at the back of the tongue. It has a very important function, that is, to close the wind pipe when swallowing. It prevents foods from entering the air way. It prevents cough and choke after swallowing. The swelling of epiglottis is known as epiglottitis, a bacterial infection. Bacteria causing this are Haemophilus influenzae (H. influenzae). Sometimes it is also caused by many other bacteria and viruses. Epiglottitis begins with high fevere and is a medical emergency which seeks immediate medical help. This may cause respiratory obstruction and may be fatal many times.
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Epiglottities also known as supraglottitis is the inflammation of epiglottis (a small flabby cartilage lid that covers the wind pipe) . When epiglottis swells, blockage of windpipe occurs and air cannot enter or exit the wind pipe. It is mainly caused by Haemophilus influenzae (is a gram negative bacterium) which is an aggressive microbe causing many serious diseases in children below five years . It is a life threatening condition that causes suffocation and death. This bacterial disease is contagious. Sometimes the disease can be caused by hot things that may injure the epiglottis which is also known as thermal Epiglottitis . This may be result from eating solid foods, drinking hot liquid, or using illicit drugs. Various symptoms of Epiglottitis are sore throat, difficulty swallowing, impaired breathing, upper respiratory infections, a muffled voice, hoarseness, fever, blue skin (cyanosis), chills and first heart beat .A high pitch whistling sound, called inspiratory stridor follows the characteristics coughing. This is very rare infections but life threatening. (Reference)
This microbe is very much virulent, because it related to the capsule formations by the bacteria. Usually type B serotype and its capsule polysaccharide, containing ribose, ribitol and phosphate. The capsule material is antiphagocytic. The bacterium can invade the blood or cerebrospinal fluid and do not attract the phagocytes. The polyribosyl ribitol phosphate (PRP) capsule is the most important virulent factor because it renders type B H. influenza resistant to phagocytosis by polymorphonuclear leukocytes in the absence of specific anticapsular antibody, and it renders type B H.influenzae resistance to phagocytosis by polymorphonuclear leukocytes in the absence of specific anticapsular antibodies. H. influenza type B was entirely responsible for the host resistance to the infection. The outer capsule of bacteria constitutes of many proteins and reveals several individual membrane proteins that may be associated with immunity. The use of polyribosyl ribitol phosphate (PRP) vaccine and, more recently, protein conjugated prp, has reduced vastly the frequency of the infection. The PRP vaccine contains of the type B capsular polysaccharide. It elicits a strong primary antibody response, like most bacterial polysaccharide. H.influenzae type B Hib conjugate vaccine, coupled the polysaccharide to protein, induce memory type antibody responses. Bacterial capsules are long polysaccharide chains consisting of smaller repeating units. This repeating unit varies among bacterial species, usually distinct among different serotypes of the same species. Capsular polysaccharide biosynthesis takes place in the cytoplasm; the resulting polysaccharide is then transported across the cytoplasmic membrane into the periplasm from where they across the outer membrane to the bacterial surface. Capsules are substituted with phospholipids at the reducing end of the polysaccharide chains. According to the prevailing model, lipidation of capsular polysaccharide is required for transport across the inner membrane and possibly for anchoring to the outer membrane . The genes responsible for the biosynthesis and surface expression of the type b capsule are located in the cap b locus, which contains three functionally distinct regions, similar to capsulation loci in other bacteria. Most isolates contain a partial tandem duplication of the cap b locus, with the two copies separated by a 1.2-kb bridge segment and flanked by IS1016 elements. The three functionally different regions of caps b locus are referring as the region 1 to 3. Region1 contains genes designated bexA, bexB, bexC, and bexD and encodes an ABC transporter system involved in the export. Region 2 contains genes currently designated orf1 to orf4 and encodes enzymes involved in biosynthesis of ribose-ribitol-5-phosphate disaccharide subunits. Region 3 contains genes referred to as hcsA and hcsB, which share significant homology with genes in a number of other encapsulated pathogens .
Hib disease is spread through the air whenever an infected person sneezes or coughs. The virulent pathogen is also present there in the nose and airways in a patient who appears well. It contends with the ciliated epithelial cell defense of the respiratory tract. Adhered to this ciliated mucosa surface in first step in the pathway of transmission and establishment on a host. Haemophilus influenza produces ciliostatic substances which prevent the cilia from brushing the bacteria. These substances are produced only when the bacteria are established. During the pathogenic state the bacteria remains susceptible to serum protein that are antibiotics and compliments. Some bacteria have serum resistance by modification of their lipopolysacchride (LPS) O-antigen side chain, thus rendering them â€˜invisibleâ€™ to the host immune defense. It can avoid the non-specific blood based defense of transferring; it limits the amount of bacteria-required iron in the blood. The bacterium can steal back iron from transferrin. Most of the strains belonging to Hi target carcinoembryonic (CEA) antigen, members of the immunoglobulin (Ig) super family. The CEA gene family comprises surface expressed (CEA) and secreted (progeny containing glycoprotein) subfamily . The membrane associated subfamily is CEACAM1. All the protein contains an N-terminal domain of 108 amino acid residue . Targeting of the CEACAM subgroup provides the organism with a wide tissue range for colonization and a means of host cell manipulation. Thus, divergent signaling mechanisms operate after ligation of bacteria with these receptors.