LECTURE Flashcards
are a group of gram-negative bacteria which possess characteristics that make them peculiar when compared to other members of the Kingdom Eubacteria.
spirochetes
Possession of a specialized locomotory apparatus, the endoflagellum or axial filaments which facilitate a movement likened to a boring cork screw
spirochetes
Reproduction by transverse binary fission
spirochetes
is a member of the phylum Spirochaetes
spirochetes (or spirochaetes)
All of its human pathogens are classified in the order (?)
Spirochaetales
three (3) genera of spirochetes:
Treponema, Borrelia, and Leptospira.
Long, slender, helically coiled, spiral, or corkscrewshaped gram-negative bacilli
spirochetes (or spirochaetes)
Has an outer sheath of glycosaminoglycan coating.
spirochetes (or spirochaetes)
Motile via the (?) which are flagella-like organelles in the periplasmic space encased by the outer membrane, begin at each end of the organism and spirally wrap around it, extending to and overlapping at the midpoint; attached to the cell wall by insertion disks located at the end of cells.
axial filaments (endoflagella)
Slender with numerous tight coils; 0.1-0.18 um iwide x 6-20 um long; has 8-20 evenly spaced coils.
Treponema
Thicker with fewer and looser coils; 0.3 µm wide x 3.0 µm long has 3-10 loose, irregular coils.
Borrelia
2 Family Spirochaetaceae
Treponema
Borrelia
Axial filaments of Treponema
6-10
Axial filaments of Borrelia
30-40
Insertion Disk/s of Treponema
1
Insertion Disk/s of Borrelia
2
Family Leptospiraceae
Leptospira
Slender, tightly coiled; ends bent to form question mark-like hooks; 0.1–0.2 µm wide x 5-15 µm long
Leptospira
Axial filaments of Leptospira
2
Insertion Disks of Leptospira
3-5
are found in the oral cavity, intestinal tract, and perigenital regions of humans and animals.
Treponema species
The pathogens are strict parasites with complex growth requirements that necessitate growing them in live cells.
Treponema species
Two species of the genus Treponema are responsible for disease in humans
T. pallidum and T. carateum.
Treponema pallidum is divided into three subspecies :
pallidum, pertenue, endemicum
Treponema pallidum subspecies pallidum: HABITAT
Humans are the only natural host of T. pallidum subspecies pallidum
Transmission occurs by the following routes:
i.Direct contact with active lesions, commonly through sexual contact
ii.Vertical transmission across the placenta may result when a woman with latent infection becomes pregnant, or when a pregnant woman becomes infected.
iii.Other routes of transmission includes:
‣Nonsexual contact with an active lesion
‣Transfusion of fresh blood products (< 48 hours of storage) from an infected person,
‣Accidental needle stick, or when infectious specimens are handled in the laboratory
Treponema pallidum subspecies pallidum: TRANSMISSION
Treponema pallidum subspecies pallidum is estimated that (?) are required for infection.
<60 treponemes
4 Diseases of Treponema pallidum
Venereal Syphilis, The Great Pox, French disease, Italian disease
is known as “the great imitator” because the varied and complex clinical manifestations of this illness can mimic many other diseases.
Syphilis
Once inoculated, the (?) penetrates an intact mucous membrane or gains access to tissue through abraded skin. It multiplies at the inoculation site, and then enters the lymphatic and circulatory system and spreads throughout the body.
treponeme
The slow generation time of this bacterium (?) as well as the delayed immune response of the host accounts for the slow, but progressive nature of the disease.
(30 hours)
The usual incubation period varies from
2 to 10 months averaging to 3 months.
The course of syphilis can be divided into predictable stages:
(1) Primary stage
(2) Secondary stage
(3) Tertiary stage (also, Late Syphilis)
This period usually occurs at an average of 3 weeks after exposure to the organism and is marked by the appearance of the primary syphilitic lesion referred to as chancre.
Primary stage of syphilis
The chancre which contains live treponemes, is a painless, non-suppurative lesion that is ulcerated with raised, firm edges and a smooth, hard base (“hard chancre”). It develops at site of inoculation
Primary stage of syphilis
commonly, the internal and external genitalia, the lips, oral cavity, nipples, fingers and the perianal region. It typically occurs singly but multiple chancres have been seen in some patients. Lymph nodes near the affected area are usually enlarged. Since it is painless, the chancre usually go unnoticed in some cases.
Primary stage of syphilis
The chancre spontaneously heal without scarring in approximately 2 to 8 weeks. However, healing is deceptive since the bacteria have already started disseminating to other organs by way of local lymph nodes and the bloodstream.
Primary stage of syphilis
This period usually occurs at an average of 3 weeks after exposure to the organism and is marked by the appearance of the primary syphilitic lesion referred to as (?)
chancre
Begins about 3 weeks to 6 months (average of 6 weeks) after the chancre heals.
Secondary stage of syphilis
This stage is characterized by widespread dissemination of spirochetes in the host’s body, mucocutaneous as well as organ involvement, and specific symptoms that include fever, sore throat, generalized lymphadenopathy, headache, lesions of the mucous membranes, and development of a red or brown rash that breaks out on all skin surfaces including the trunk, arms, and even palms and soles.
Secondary stage of syphilis
The spread of spirochetes into the organs result to major complications that develop in the bones, hair follicles, joints, liver, eyes, brain, and kidneys.
Secondary stage of syphilis
This stage usually last for 2 to 8 weeks and in some, can relapse.
Secondary stage of syphilis
After this stage, approximately 1/3 of untreated patients exhibit biological cure, with negative serological tests. Another third remain latent for life but have reactive sera. The remaining third ultimately develop tertiary or late syphilis.
Secondary stage of syphilis
The lesions may enlarge and coalesce to produce pale plaques referred to as
condyloma lata
During this period, the bacteria are no longer present, and clinical manifestations of the disease are absent but anti-treponeme antibodies can be readily detected.
Latent Syphilis
After resolution of secondary syphilis, (?)% of infected persons enter a period of latency which highly varies and can last for 20 years of longer.
30%
The period of latency is divided into:
(1) Early Latent Syphilis
(2) Late Latent Syphilis
occurs within 1 year of infection and characterized by occasional relapses
Early Latent Syphilis
occurs greater than 1 year of infection, relapses are uncommon.
Late Latent Syphilis
Only a fraction of patients progress into this period several years up to decades following initial infection.
(3) Tertiary stage (also, Late Syphilis)
Infected persons rarely progress to this period because of widespread use of antibiotics to treat infections.
3) Tertiary stage (also, Late Syphilis)
During this period, the combined action of the infection and the body’s response to it produce severe pathologic complications.
(3) Tertiary stage (also, Late Syphilis)
marked by development of granulomatous lesions (called gummas) in the skin, bones, and the liver which can occasionally lead to death.
Benign tertiary syphilis
development of granulomatous lesions in the skin
gummas
may involve any part of the nervous system but typically affects the blood vessels in the brain, cranial nerves, and dorsal roots of the spinal cord. The reactions can be diverse and include severe headaches, convulsions, behavioral changes, atrophy of the optic nerve which leads to blindness. Atrophy of the spinal cord leads to muscle wasting and loss of coordination.
Neurosyphilis
results from damage to small arteries in the aortic wall, cardiovascular lesions, aneurysms, and aortic valve insufficiency.
Cardiovascular syphilis