Mycoplasmas and Spirochetes Flashcards
`TALK ABOUT Genus – Mycoplasma
is a genus of bacteria that lack a cell wall around their cell
membranes.
Mycoplasma species are the smallest bacterial cells yet discovered, can survive without oxygen, and come in various shapes.
It is a human pathogen that causes the disease mycoplasma pneumonia
M. pneumonia are the only bacterial cells that possess cholesterol in their
cell membrane.
what is the main features of Mycoplasma pneumoniae ?
The main feature is the absence of a cell wall and mycoplasmas stain poorly with Gram stain, and antibiotics that inhibit cell wall (peptidoglycan) synthesis (e.g., penicillins and cephalosporins) are ineffective
It is the only bacterial membrane that contains cholesterol
what are Pathogenesis & Epidemiology Mycoplasma pneumonia
is a pathogen only for humans cause by Human-to-human transmission
contains specific - P1 adherence protein: promotes adherence to the respiratory- bronchial epithelium
It does produce hydrogen peroxide, which contributes to the damage to the
respiratory tract cells.
autoantibodies are produced against red cells
(cold agglutinins) and brain, lung, and liver cells.
Antibody in a patient’s serum will agglutinate human red
blood cells at 4°C, but not at 37°C. ( cold )
what are the high risk factors for Mycoplasma pneumoniae
Age, primarily young adults
• Those living in close quarters:
• Military recruits
• Prisoners
what are the bacteria that cause atypical pneumonia and what does it means
Atypical pneumonia is also caused by Legionella pneumophila [Legionnaires’ disease], Chlamydia pneumoniae, Chlamydia psittaci [psittacosis],
• The term “atypical” means that a causative bacterium cannot be isolated on
routine media in the diagnostic laboratory
laboratory diagnosis of mycoplasma pneumonia
• Diagnosis is usually not made by culturing sputum samples
they are positive for cold agglutinins. but its not specific
laboratory diagnosis of mycoplasma pneumonia
• Diagnosis is usually not made by culturing sputum samples
they are positive for cold agglutinins. but its not specific
Treatment and prevention of mycoplasma pneumonia
erythromycin, doxycycline
Penicillins and cephalosporins are inactive because the organism has no cell wall.
There is no vaccine
WHAT ARE THE TYPES OF SPIROCHETES ?
Genus - Treponema ( which causes syphilis and the nonvenereal treponematoses )
Genus - Borrelia , which causes Lyme disease and relapsing fever
Genus - Leptospira which causes leptospirosis
TALK ABOUT SPIROCHETES
• Spirochetes are thin-walled, flexible, gram-negative spiral rods.They are motile
TALK ABOUT Treponema pallidum
Treponema is a genus of spiral-shaped bacteria.
It cause syphilis
grows very slowly they do not grow on a bacterial media
• The antigens of T. pallidum induce specific antibodies, which can be detected
by immunofluorescence or hemagglutination tests They also induce nonspecific antibodies (reagin), which can be detected by
the flocculation of lipids (cardiolipin) extracted from normal mammalian
tissues (e.g., beef heart).
Transmission & Epidemiology for Treponema pallidum
transmitted from spirochete-containing lesions of skin or mucous membranes
infects only a human organism. There is no animal reservoir
Pathogenesis & Clinical Findings Treponema pallidum
• The organism often infects the endothelium of small blood vessels, causing
endarteritis. This occurs during all stages of syphilis
Treponema pallidum also causes congenital syphilis
In congenital syphilis, no antibody is formed against T. pallidum
because the fetus is tolerant to the organism
what are the three stages of syphilis
• 1st stage - Is primary syphilis, the spirochetes multiply at the site of
inoculation and a local, nontender ulcer (chancre) usually forms
2nd stage - One to 3 months later, the lesions of secondary syphilis may occur. Moist lesions on the genitals are called condylomata lata.
• These lesions are rich in spirochetes and are highly infectious, but they also heal spontaneously. Patchy alopecia also occurs
(RPR) and (FTA-ABS)
tests are usually positive
3rd stage - In the remaining one-third of people, the disease progresses to
the tertiary stage. Tertiary syphilis may show granulomas (gummas)
• Immunity to syphilis is incomplete. Antibodies to the organism are
produced but do not stop the progression of the disease
Laboratory Diagnosis OF • Treponema pallidum
Microscopy - Spirochetes are demonstrated in the lesions of primary or secondary syphilis, such as chancres or condylomata lata,
Nonspecific Serologic Tests
Specific Serologic Tests
treatment and prevention of Treponema pallidum
Penicillin G is effective in the treatment of all stages of syphilis.
Prevention depends on early diagnosis and adequate treatment, safe
sex, administration of antibiotic after suspected exposure
there is no vaccine
TALK ABOUT . Nonvenereal Treponematoses
These are infections caused by spirochetes that are virtually
indistinguishable from those caused by T. pallidum.
• They are endemic in populations and are transmitted by direct
contact.
• All these infections result in positive (nontreponemal and
treponemal) results on serologic tests for syphilis.
• No growth on bacteriologic media.
• All can be cured by penicillin
TALK ABOUT BORRELIA
Borrelia is motile, Gram-negative, with pointed ends. Commensal in mouth and genitals.
IT is a genus of bacteria of the spirochete phylum. It causes
Lyme disease, also called Lyme borreliosis, a zoonotic, vector-borne
disease transmitted primarily by ticks and by lice, depending on the
species of bacteria.
- They are transmitted by arthropods.
- They cause two major diseases, Lyme disease and relapsing fever
TALK ABOUT BORRELIA burgdorferi
Borrelia burgdorferi causes Lyme disease, Lyme disease is the most common tick-borne disease
Borrelia burgdorferi is a flexible, motile spirochete that can be
visualized by dark-field microscopy and by Giemsa and silver stains
Transmission & Epidemiology of Borrelia burgdorferi
is transmitted by tick bite , The main reservoir of the organism are of small mammals, Large mammals, especially deer, are an obligatory host in the tick’s life cycle but are not an important reservoir of the organism
• The nymphal stage of the tick transmits the disease more often than the adult and larval stages do
The tick must feed for 24 to 48 hours to
transmit an infectious dose. This means that
inspecting the skin after being exposed can
prevent the disease
Pathogenesis of Borrelia burgdorferi
• The organism must adapt to two markedly different hosts, the tick and the
mammal (either mice or humans). It does so by changing its outer surface
protein (OSP). These OSPs vary antigenically within humans.
• Multiple episodes of Lyme disease are due to reinfection, rather than relapse
caused by rea ctivation of the organism. There is no evidence for a latent stage
of B. burgdorferi
Clinical Findings of Borrelia burgdorferi
In stage 1 (early localized stage), the most common finding is erythema chronicum
migrans
In stage 2 (early disseminated stage), which occurs weeks to months later,
cardiac and neurologic involvement predominates
- A latent phase lasting weeks to months typically ensues.
- In stage 3 (late disseminated stage), arthritis, usually of the large joints (e.g., knees)
Treatment & Prevention of Borrelia burgdorferi
doxycycline or amoxicillin. Amoxicillin should be used in pregnant women and
young children, as doxycycline is contraindicated
Prevention involves wearing protective clothing and using insect repellents. Examining the skin carefully for ticks is also very important, because the tick must
feed for 24 to 48 hours to transmit an infective dose
talk about Borrelia recurrentis & Borrelia hermsii
• Borrelia recurrentis, Borrelia hermsii, and several other borreliae cause relapsing fever
Borrelia recurrentis is transmitted from person to person by the human body louse
During infection, the arthropod bite introduces spirochetes, which then multiply
in many tissues, producing fever, chills, headaches, and multiple-organ dysfunction. Each attack is terminated as antibodies arise
