ONPG (\u03b2-Galactosidase)<\/a><\/td> | Negative (-)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<\/span>Burkholderia pseudomallei<\/em> Associated Diseases<\/strong><\/span><\/h2>\n\n\n\n\n- Burkholderia pseudomallei<\/em> is a causative agent of a deadly human disease \u2018melioidosis<\/strong>\u2019. This disease is mainly seen in humans and animals like pigs, goats, and sheep. This disease is transmitted by direct transmission of bacterium from soil or water to humans via skin cuts or wounds, ingestion, or inhalation route. Person-to-person or animal-to-person transmission is not reported yet. The death rate of melioidosis is very high \u2013 about 20 to 40% even with treatment. It is estimated that about 165,000 are infected with this disease per year and 89,000 of them can\u2019t survive through it. (Limmathurotsakul D, Golding N, Dance DA, et al.\u00a0, 2016)<\/em><\/li>\n\n\n\n
- Most of the cases are reported in patients with diabetes, excessive alcohol use, chronic lung infections (cystic fibrosis and COPD), chronic renal diseases, hypertension, and immunocompromised conditions. Diabetes is the major risk factor for this disease because nearly 40% of melioidosis cases are reported in diabetic patients. <\/li>\n\n\n\n
- Diverse clinical presentations are seen in melioidosis ranging from mild fever and skin rashes to severe conditions like pneumonia, bacteremia, abscesses in internal organs like the liver, spleen, kidney, and prostate, septic shock, osteomyelitis, septic arthritis, even CNS infection in rare cases. <\/li>\n\n\n\n
- The clinical manifestations of melioidosis resemble those of tuberculosis so in many regions where melioidosis is not common, this disease is frequently misdiagnosed as tuberculosis. Also, cases of melioidosis misdiagnosed as aspergilloma based on cavitary lesions in chest X-rays and CT scans are also reported. <\/li>\n<\/ul>\n\n\n\n
<\/span>Virulence Factors of Burkholderia pseudomallei<\/em><\/strong><\/strong><\/span><\/h2>\n\n\n\nB. pseudomallei<\/em> exhibit numerous virulence factors, that help in disease pathogenesis, viz. <\/p>\n\n\n\n\n- Capsule and Pili<\/strong>: When the bacteria initially reach the host body, the capsule and pili aid in the initial epithelial or mucosal adhesion. <\/li>\n\n\n\n
- Fimbriae:<\/strong> Type I fimbriae are present on the outer surface of the bacteria and these help in attachment with D-mannosylated sugars of surface glycoproteins of the host\u2019s intestinal epithelium and macrophages. <\/li>\n\n\n\n
- Autotransporters:<\/strong> These are outer membrane-anchored proteins that function as adhesins and help in bacterial adherence and invasion of human lung cells. <\/li>\n\n\n\n
- Lipopolysaccharide (LPS):<\/strong> LPS, especially the O<\/em>-antigen polysaccharide chain (O<\/em>-PS) component of LPS, suppresses the host\u2019s immune response in an early stage of infection.<\/li>\n\n\n\n
- Oxidative stress-protecting factors<\/strong> like sigma factors, RpoS, and RpoE, catalase-peroxidase I enzyme, superoxide dismutase, putative ferritin DPS-family DNA binding protein, etc. are synthesized to protect against reactive oxygen species (ROS). <\/li>\n\n\n\n
- Type III Secretion Systems (T3SS):<\/strong> These T3SS help bacteria escape endocytic vesicles and phagosomes and enter the host\u2019s cytoplasm. <\/li>\n\n\n\n
- Type VI Secretion Systems (T6SS):<\/strong> T6SS are important virulence factors that help in bacterial survival, cytotoxicity, multinucleated giant cell (MNGC) formation, etc. <\/li>\n\n\n\n
- Bacterial phospholipases:<\/strong> These help in survival inside host cells, help in plaque formation, and induce cytotoxicity. <\/li>\n\n\n\n
- Toxins:<\/strong><\/strong> B. pseudomallei<\/em> are capable of secreting a toxin called Burkholderia<\/em> Lethal Factor 1 (BLF1). <\/li>\n\n\n\n
- Burkholderia<\/em><\/strong> Intracellular Motility A (BimA) Protein<\/strong>: BimA protein helps in polymerization of host cell actin. This polymerization forms actin tails which are used by B. pseudomallei<\/em> to propel themselves inside the host\u2019s cytoplasm towards the host cell membrane. <\/li>\n\n\n\n
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