OPTO435 Microbiology II Gamal El-Hiti

Chlamydia trachomatis and Mycobacterium tuberculosis Lecture Six

Outcomes Learning Outcomes To provide the basic knowledge about Chlamydia trachomatis Treatment and prevention of diseases caused by Chlamydia trachomatis To provide the basic knowledge about Treponema pallidum Treatment and prevention of diseases caused by Treponema pallidum To acquire the basic knowledge about Mycobacterium tuberculosis 11/03/2018 OPT435 L06 – W08

Chlamydiae  The family Chlamydiaceae consists of small obligate parasitic bacteria that depend on the host cell for energy in the forms of ATP and NAD+.  The family has three important human pathogens.  Chlamydia pneumoniae, Chlamydia psittaci and Chlamydia trachomatis. 11/03/2018 OPT435 L06 – W08

Chlamydiae  Chlamydiae are small, round-to-ovoid organisms that vary in size during the different stages of their replicative cycle.  The chlamydial cell envelope consists of two lipid bilayers resembling a Gram-negative envelope.  The Chlamydial DNA genome is small. 11/03/2018 OPT435 L06 – W08

Chlamydiae  Chlamydiae have ribosomes and can synthesize their own proteins.  Therefore, they are sensitive to antibiotics that inhibit protein biosynthesis process.  Physiology of Chlamydiae  Chlamydiae are energy parasites that require the living cells for growth.  They are unable to synthesize their own ATP or regenerate NAD+ by oxidation.  Chlamydiae produce CO2 from glucose and carry out bacterial metabolic activities. 11/03/2018 OPT435 L06 – W08

Chlamydiae  Pathogenesis of Chlamydiae  Chlamydiae have a unique life cycle, with morphologically distinct infectious and reproductive forms. 11/03/2018 OPT435 L06 – W08

Chlamydiae 11/03/2018 OPT435 L06 – W08

Chlamydiae  Clinical significance of Chlamydiae  Chlamydiae are not stained using the Gram stain protocol.  It can be visualized under light microscopy by stains that preserve the host cell.  Direct immunofluorescence is also a common as a useful procedure.  In C. trachomatis, a matrix of glycogen-like material accumulates in the inclusions, which can be shown by staining with iodine.  Other species do not produce this reaction. 11/03/2018 OPT435 L06 – W08

Chlamydiae  Nongonococcal urethritis (NGU)  Annually, more than 4 million urogenital Chlamydia trachomatis infections occur in the US in young and sexually active individuals.  In men, the urethra is the initial site of infection.  Women may present with cervicitis and/or urethritis.  Infections are often asymptomatic, although communicable. 11/03/2018 OPT435 L06 – W08

Chlamydiae 11/03/2018 OPT435 L06 – W08

Chlamydiae  Chlamydial nongonococcal urethritis is similar to infections caused by Neisseria gonorrhoeae, although the incubation time is longer (2 to 3 weeks).  Two infections often occur simultaneously. 11/03/2018 OPT435 L06 – W08

Chlamydiae  Neonatal conjunctivitis  Over 50% of the infants born to women infected with Chlamydia trachomatis, serotypes D–K will contract symptomatic infection on passage through the birth canal.  The most common presentation is the inclusion conjunctivitis of the newborn.  This acute, purulent conjunctivitis usually heals after the appropriate antimicrobial therapy, without permanent damage to the eye. 11/03/2018 OPT435 L06 – W08

Chlamydiae  If C. trachomatis infections untreated, the infection can lead to permanent scarring of the cornea or conjunctiva. 11/03/2018 OPT435 L06 – W08

Chlamydiae  Treatment and prevention  Chlamydiae are sensitive to a number of broad-spectrum antibacterial drugs.  Resistant strains have not been reported in the clinical setting.  Azithromycin and tetracycline are currently the drugs of choice.  Erythromycin should be used in young children and pregnant women due to the effects of tetracyclines on the teeth and bones. 11/03/2018 OPT435 L06 – W08

Treponema pallidum  Syphilis is primarily a sexually transmitted infection caused by Treponema pallidum (spirochete).  Starts with a small lesion.  Several progressive stages of the disease can span a period of 30 years or more.  Often ends in syphilitic dementia or cardiovascular damage.  The causative organism of syphilis is extremely fastidious and fragile. 11/03/2018 OPT435 L06 – W08

Treponema pallidum 11/03/2018 OPT435 L06 – W08

Treponema pallidum  Pathogenesis of Treponema pallidum  Treponema pallidum is transmitted by sexual contact or transplacental.  Treponema pallidum is so sensitive to the environment and cannot survival outside the host cells for more than few minutes.  Treponema pallidum enters the body through a break in the skin or by penetrating the mucous membranes.  Syphilis occurs in three stages as primary, secondary and tertiary stages. 11/03/2018 OPT435 L06 – W08

Treponema pallidum  Primary syphilis is a chancre.  Secondary syphilis is a rash and may be accompanied by syphilitic hepatitis.  Tertiary syphilis is a gumma of skin. 11/03/2018 OPT435 L06 – W08

Treponema pallidum  Treatment and prevention  One single treatment with penicillin is curative for primary and secondary syphilis.  No antibiotic resistance has been reported.  For patient sensitive to penicillin, tetracyclines may be effective.  There are over 10,000 new cases of syphilis in the US every year.  There is no vaccine against T. pallidum and prevention depends on safe sexual practices. 11/03/2018 OPT435 L06 – W08

Mycobacteria  Mycobacteria are slender rods with lipid-rich cell walls.  Mycobacterial cell wall is ca. 60% lipid.  Size is 3  3 m.  They are resistant to penetration by chemical dyes such as those used in the Gram stain.  Mycobacteria are strictly aerobic. 11/03/2018 OPT435 L06 – W08

Mycobacteria  The unusual cell walls made mycobacteria convey resistance to disinfectants and strong acids or alkalis.  Mycobacteria are also resistant to dry environment.  Can not resist heat or ultraviolet irradiation.  Most species grow slowly with generation times of 8 to 24 hours.  Mycobacterium tuberculosis causes tuberculosis (TB) in Human that can be spread from one person to another through air. 11/03/2018 OPT435 L06 – W08

Mycobacterium tuberculosis 11/03/2018 OPT435 L06 – W08

Mycobacterium tuberculosis 11/03/2018 OPT435 L06 – W08

Mycobacterium tuberculosis 11/03/2018 OPT435 L06 – W08

Mycobacterium tuberculosis  Epidemiology of M. tuberculosis  Patients with active pulmonary tuberculosis shed large numbers of organisms by coughing, creating aerosol droplet nuclei.  The organisms can remain viable as droplet nuclei suspended in room air for at least 30 minutes.  Transmission from one person to another occurs by inhalation of the aerosol.  A single infected person can pass the organism to numerous people. 11/03/2018 OPT435 L06 – W08

Mycobacterium tuberculosis  Pathogenicity of M. tuberculosis  Mycobacteria will multiply after inhalation.  Within 2 to 4 weeks, many bacilli are destroyed by the immune system, but some survive and are spread by the blood.  M. tuberculosis grow within host cells.  When engulfed by macrophages, bacterial sulfolipids inhibit the fusion of phagocytic vesicles with lysosomes.  M. tuberculosis remains viable within the host for decades. 11/03/2018 OPT435 L06 – W08

Mycobacterium tuberculosis 11/03/2018 OPT435 L06 – W08

Mycobacterium tuberculosis  Immunity against M. tuberculosis  M. tuberculosis stimulates both a humoral and a cell mediated immune response.  Clinical significance of M. tuberculosis  Primary tuberculosis occurs in a person who had no previous contact with the organism.  For the majority of cases (ca. 95%), the infection becomes arrested, and most people are unaware of this initial encounter.  The only evidence of tuberculosis may be a positive tuberculin test. 11/03/2018 OPT435 L06 – W08

Mycobacterium tuberculosis  A chest radiograph sometimes shows the initial pulmonary nodule.  Mycobacterium tuberculosis may be accompanied by systemic involvement such granulomatous conjunctivitis.  Tuberculin reaction  A test that is a manifestation of delayed hypersensitivity to protein antigens of Mycobacterium tuberculosis.  A positive reaction usually develops 4 to 6 weeks after initial contact with the organism. 11/03/2018 OPT435 L06 – W08

Mycobacterium tuberculosis 11/03/2018 OPT435 L06 – W08

Mycobacterium tuberculosis  Treatment and prevention  Several chemotherapeutic agents are effective against M. tuberculosis.  Isoniazid, rifampin, ethambutol, streptomycin and pyrazinamide are the principal or “first-line” drugs.  Public health measures (e.g. tuberculin tests and chest radiographs) needs to be taken to prevent illness.  A vaccine against tuberculosis has been available since early in the 20th century. 11/03/2018 OPT435 L06 – W08

Mycobacterium tuberculosis 11/03/2018 OPT435 L06 – W08

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