Pathogenesis Archives | Microbe Notes

Virulence factors, Pathogenesis and Clinical manifestations of Legionella pneumophila

May 12, 2020January 15, 2018 by Sagar Aryal

Virulence factors of Legionella pneumophila Heat shock protein 60: enhances invasion and cytokine expression in macrophages. Outer membrane protein: binding with and delivery of packaged materials into the eukaryotic cells. inhibit the fusion of phagosomes with lysosomes. Macrophage infectivity potentiator (Mip) protein promotes adherence and phagocytosis. Genes encoding for the type II secretion systems required for intracellular growth is required for full …

Pathogenesis and Clinical Manifestations of Coxiella burnetii

February 4, 2021December 1, 2017 by Sagar Aryal

Pathogenesis of Coxiella burnetii Human infection usually follows inhalation of aerosols containing C. burnetii. It is estimated that only between 1 and 10 bacteria are necessary to cause infection. C. burnetii has also been known to enter the body via other mucous membranes, abrasions, and the gastrointestinal tract through consumption of milk from infected animals. C. burnetii exists in two antigenic forms …

Pathogenesis and Clinical Manifestations of Chlamydia trachomatis

February 4, 2021November 21, 2017 by Sagar Aryal

Pathogenesis of Chlamydia trachomatis Chlamydia are acquired by direct contact with mucous membranes or abraded skin, that is, by sexual contact or by direct inoculation into the eye in the case of trachoma or neonatal conjunctivitis. Two forms of the organism are needed for infection and disease to occur: the infectious, extracellular form called an elementary body (EB) and the …

Pathogenesis and Clinical Manifestations of Leptospira interrogans

February 4, 2021November 15, 2017 by Sagar Aryal

Pathogenesis of Leptospira interrogans Leptospires usually enter the body through the mucous membranes of the upper respiratory tract or the conjunctivae, or through abraded skin, following exposure to contaminated water, infected urine or animal tissues. Ingestion is considered to be less important. The severity of the leptospirosis depends on (a) host immunity, (b) virulence of infecting strain, and (c) the …

Pathogenesis and Clinical Manifestations of Borrelia burgdorferi

February 4, 2021November 9, 2017 by Sagar Aryal

Pathogenesis of Lyme disease caused by Borrelia burgdorferi Lyme disease is caused by the spirochete B. burgdorferi, which is transmitted by the bite of a small tick of the genus Ixodes. Humans are “accidental” hosts for B. burgdorferi because spirochetes from infected people are not transmitted to other hosts. While in the midgut of the Ixodes tick between feeding periods, the spirochetes …

Virulence factors, Pathogenesis and Clinical manifestations of Streptococcus pneumoniae

February 4, 2021November 3, 2017 by Sagar Aryal

Virulence factors of Streptococcus pneumoniae Polysaccharide capsule The capsule is antiphagocytic, inhibiting complement deposition and phagocytosis. 2. Cell wall associated polymers and proteins Teichoic acid – binds to epithelial cells and activates alternative complement pathway Protein adhesion – binds to epithelial cells Peptidogylcan – activates alternative complement pathway Phosphorylcholine – mediates invasion of host cell F protein – mediates attachment …

Pathogenesis and Clinical manifestations of Francisella tularensis

February 4, 2021November 1, 2017 by Sagar Aryal

Pathogenesis of Francisella tularensis Francisella tularensis is carried by many species of wild rodents, rabbits, beavers. Humans become infected by handling the carcasses or skin of infected animals, by inhaling infective aerosols or ingesting contaminated water, through insect vectors and by being bitten by carnivores that have themselves eaten infected animals. Humans are infected by fewer than 50 organisms by …

Pathogenesis and Clinical manifestations of Corynebacterium diphtheriae

February 4, 2021October 28, 2017 by Sagar Aryal

Pathogenesis of Corynebacterium diphtheriae In nature, C diphtheriae occurs in the respiratory tract, in wounds, or on the skin of infected persons or normal carriers. It is spread by droplets or by contact to susceptible individuals; the bacilli then grow on mucous membranes or in skin abrasions, and those that are toxigenic start producing toxin. Diphtheria toxin is the major …

Virulence factors, Pathogenesis and Clinical manifestations of Listeria monocytogenes

February 4, 2021October 26, 2017 by Sagar Aryal

Virulence factors of Listeria monocytogenes 1. Adhesion proteins (Ami, Fbp A, flagellin) Mediate bacterial binding to host cell that contribute to virulence. 2. Listeriolysin O A hemolytic and cytotoxic toxin that allows for survival within phagocytes. 3. Internalin Cell surface protein that induces phagocytosis. 4. Act A Induces actin polymerization on the surface of host cells, producing cellular extensions and facilitating …

Pathogenesis and Clinical manifestations of Treponema pallidum

February 4, 2021October 23, 2017 by Sagar Aryal

Pathogenesis of Treponema pallidum The two major routes of transmission of Treponema pallidum are sexual and transplacental. Sexual exposure to a person who has an active syphilitic chancre carries a high probability of acquiring syphilis. The organisms enter a susceptible host by penetration of intact mucous membranes or the minute abrasions in the skin surface that occur during sexual intercourse. …