مصري فيت

السلام عليكم ورحمة الله وبركاته نامل ان تكون في اتم صحه وعافيه
مصري فيت

منتدي لعلوم الطب البيطري وما يشملها


    بعض اختصارات الميكروبيولوجي-2

    شاطر

    admin
    Admin

    المساهمات : 2529
    تاريخ التسجيل : 22/03/2010
    العمر : 56
    الموقع : O.KATTAB@YAHOO.COM

    بعض اختصارات الميكروبيولوجي-2

    مُساهمة من طرف admin في الإثنين أغسطس 29, 2011 11:18 pm


    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Bacteroides melaninogenicus.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Haemophilus influenzae

    Diseases

    Sinusitis, otitis media, and pneumonia are common.
    Epiglottitis is uncommon, but H. influenzae is the most important cause.
    H. influenzae used to be a leading cause of meningitis, but the vaccine
    has greatly reduced the number of cases.

    Characteristics

    Small gram-negative (coccobacillary) rods. Requires factors
    X (hemin) and V (NAD) for growth. Of the six capsular polysaccharide types, type
    b causes 95% of invasive disease. Type b capsule is polyribitol phosphate.

    Habitat and Transmission

    Habitat is the upper respiratory tract. Transmission is via
    respiratory droplets.

    Pathogenesis

    Polysaccharide capsule is the most important determinant of
    virulence. Unencapsulated ("untypeable") strains cause mucosal infections but
    not invasive infections. IgA protease is produced. Most cases of meningitis
    occur in children younger than 2 years of age, because maternal antibody has
    waned and the immune response of the child to capsular polysaccharides can be
    inadequate. No exotoxins identified.

    Laboratory Diagnosis

    Gram-stained smear plus culture on chocolate agar. Growth
    requires both factors X and V. Determine serotype by using antiserum in various
    tests, e.g., latex agglutination. Capsular antigen can be detected in serum or
    cerebrospinal fluid. Serologic test for antibodies in patient's serum not
    useful.

    Treatment

    Ceftriaxone is the treatment of choice for meningitis.
    Approximately 25% of strains produce [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]-lactamase.

    Prevention

    Vaccine containing the type b capsular polysaccharide
    conjugated to diphtheria toxoid or other protein is given between 2 and 18
    months of age. Rifampin can prevent meningitis in close
    contacts.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Bordetella pertussis

    Disease

    Whooping cough (pertussis).

    Characteristics

    Small gram-negative rods.

    Habitat and Transmission

    Habitat is the human respiratory tract. Transmission is via
    respiratory droplets.

    Pathogenesis

    Pertussis toxin stimulates adenylate cyclase by adding
    ADP-ribose onto the inhibitory G protein. Toxin has two components: subunit A,
    which has the ADP-ribosylating activity, and subunit B, which binds the toxin to
    cell surface receptors. Pertussis toxin causes lymphocytosis in the blood by
    inhibiting chemokine receptors. Inhibition of these receptors prevents
    lymphocytes from entering tissue, resulting in large numbers being retained in
    the blood. Inhibition of chemokine receptors occurs because pertussis toxin
    ADP-ribosylates the inhibitory G protein which prevents signal transduction
    within the cell. In addition, extracellular adenylate cyclase is produced, which
    can inhibit killing by phagocytes. Tracheal cytotoxin damages ciliated
    epithelium of respiratory tract.

    Laboratory Diagnosis

    Gram-stained smear plus culture on Bordet-Gengou agar.
    Identified by biochemical reactions and slide agglutination with known antisera.
    PCR tests, if available, are both sensitive and specific. Serologic tests for
    antibody in patient's serum not useful.

    Treatment

    Erythromycin.

    Prevention

    The acellular vaccine containing pertussis toxoid and four
    other purified proteins is recommended rather than the killed vaccine, which
    contains whole organisms. Usually given to children in combination with
    diphtheria and tetanus toxoids (DTaP).
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Legionella pneumophila

    Disease

    Legionnaires' disease ("atypical" pneumonia).

    Characteristics

    Gram-negative rods, but stain poorly with standard Gram
    stain. Require increased iron and cysteine for growth in culture.

    Habitat and Transmission

    Habitat is environmental water sources. Transmission is via
    aerosol from the water source. Person-to-person transmission does not
    occur.

    Pathogenesis

    Aside from endotoxin, no toxins, enzymes, or virulence
    factors are known. Predisposing factors include being older than 55 years of
    age, smoking, and having a high alcohol intake. Immunosuppressed patients, e.g.,
    renal transplant recipients, are highly susceptible. The organism replicates
    intracellularly, therefore cell-mediated immunity is an important host defense.
    Smoking damages alveolar macrophages, which explains why it predisposes to
    pneumonia.

    Laboratory Diagnosis

    Microscopy with silver impregnation stain or fluorescent
    antibody. Culture on charcoal yeast extract agar containing increased amounts of
    iron and cysteine. Urinary antigen provides rapid diagnosis. Diagnosis can be
    made serologically by detecting rise in antibody titer in patient's serum.

    Treatment

    Azithromycin or erythromycin. Rifampin can be added in
    severe cases.

    Prevention

    No vaccine or prophylactic drug is
    available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Brucella Species (e.g., B. abortus, B. suis, B.
    melitensis
    )

    Disease

    Brucellosis (undulant fever).

    Characteristics

    Small gram-negative rods.

    Habitat and Transmission

    Reservoir is domestic livestock. Transmission is via
    unpasteurized milk and cheese or direct contact with the infected animal.

    Pathogenesis

    Organisms localize in reticuloendothelial cells, especially
    the liver and spleen. Able to survive and replicate intracellularly. No
    exotoxins. Predisposing factors include consuming unpasteurized dairy products
    and working in an abattoir.

    Laboratory Diagnosis

    Gram-stained smear plus culture on blood agar plate.
    Identified by biochemical reactions and by agglutination with known antiserum.
    Diagnosis may be made serologically by detecting antibodies in patient's
    serum.

    Treatment

    Tetracycline plus rifampin.

    Prevention

    Pasteurize milk; vaccinate cattle. No human vaccine is
    available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Francisella tularensis

    Disease

    Tularemia.

    Characteristics

    Small gram-negative rods.

    Habitat and Transmission

    Reservoir is many species of wild animals, especially
    rabbits, deer, and rodents. Transmission is by ticks (e.g., Dermacentor),
    aerosols, contact, and ingestion.

    Pathogenesis

    Organisms localize in reticuloendothelial cells. No
    exotoxins.

    Laboratory Diagnosis

    Culture is rarely done, because special media are required
    and there is a high risk of infection of laboratory personnel. Diagnosis is
    usually made by serologic tests that detect antibodies in patient's serum.

    Treatment

    Streptomycin.

    Prevention

    Live, attenuated vaccine for persons in high-risk
    occupations. Protect against tick bites.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Pasteurella multocida

    Disease

    Wound infection, e.g., cellulitis.

    Characteristics

    Small gram-negative rods.

    Habitat and Transmission

    Reservoir is the mouth of many animals, especially cats and
    dogs. Transmission is by animal bites.

    Pathogenesis

    Spreads rapidly in skin and subcutaneous tissue. No
    exotoxins.

    Laboratory Diagnosis

    Gram-stained smear and culture.

    Treatment

    Penicillin G.

    Prevention

    Ampicillin should be given to individuals with cat bites.
    There is no vaccine.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Yersinia pestis

    Disease

    Bubonic and pneumonic plague.

    Characteristics

    Small gram-negative rods with bipolar ("safety pin")
    staining. One of the most virulent organisms, i.e., very low
    ID50.

    Habitat and Transmission

    Reservoir is wild rodents, e.g., rats, prairie dogs, and
    squirrels. Transmission is by flea bite.

    Pathogenesis

    Virulence factors include endotoxin, an exotoxin, two
    antigens (V and W), and an envelope (capsular) antigen that protects against
    phagocytosis. V and W proteins allow organism to grow within cells. Bubo is a
    swollen inflamed lymph node, usually located in the region of the flea
    bite.

    Laboratory Diagnosis

    Gram-stained smear. Other stains, e.g., Wayson's, show
    typical "safety-pin" appearance more clearly. Cultures are hazardous and should
    be done only in specially equipped laboratories. Organism is identified by
    immunofluorescence. Diagnosis can be made by serologic tests that detect
    antibody in patient's serum.

    Treatment

    Streptomycin either alone or in combination with
    tetracycline. Strict quarantine for 72 hours.

    Prevention

    Control rodent population and avoid contact with dead
    rodents. Killed vaccine is available for persons in high-risk occupations. Close
    contacts should be given tetracycline.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Mycobacterium tuberculosis

    Diseases

    Tuberculosis.

    Characteristics

    Aerobic, acid-fast rods. High lipid content of cell wall,
    which prevents dyes used in Gram stain from staining organism. Lipids include
    mycolic acids and wax D. Grows very slowly, which requires that drugs be present
    for long periods (months). Produces catalase, which is required to activate
    isoniazid to the active drug.

    Habitat and Transmission

    Habitat is the human lungs. Transmission is via respiratory
    droplets produced by coughing.

    Pathogenesis

    Granulomas and caseation mediated by cellular immunity,
    i.e., macrophages and CD4-positive T cells (delayed hypersensitivity). Cord
    factor (trehalose mycolate) correlates with virulence. No exotoxins or
    endotoxin. Immunosuppression increases risk of reactivation and
    dissemination.

    Laboratory Diagnosis

    Acid-fast rods seen with Ziehl-Neelsen (or Kinyoun) stain.
    Slow-growing (3–6 weeks) colony on Löwenstein-Jensen medium. Organisms produce
    niacin and are catalase-positive. Serologic tests for antibody in patient's
    serum not useful.

    Skin Test

    PPD skin test is positive if induration measuring 10 mm or
    more appears 48 hours after inoculation. Induration is caused by a delayed
    hypersensitivity response. Positive skin test indicates that the person has been
    infected but not necessarily that the person has the disease tuberculosis.

    Treatment

    Long-term therapy (6–9 months) with three drugs, isoniazid,
    rifampin, and pyrazinamide. A fourth drug, ethambutol, is used in severe cases
    (e.g., meningitis), in immunocompromised patients (e.g., those with AIDS), and
    where the chance of isoniazid-resistant organisms is high, as in Southeast
    Asians. Most patients become noninfectious within 2 weeks of adequate therapy.
    Treatment of latent (asymptomatic) infections consists of isoniazid taken for
    6–9 months. Multidrug-resistant (MDR) strains have emerged and require other
    drug combinations.

    Prevention

    BCG vaccine containing live, attenuated Mycobacterium
    bovis
    organisms may prevent or limit extent of disease but does not prevent
    infection with M. tuberculosis. Vaccine used rarely in the United States
    but widely used in parts of Europe and Asia.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Atypical Mycobacteria

    These mycobacteria are called atypical because they differ
    from M. tuberculosis in various ways. The most important difference is
    that the atypicals are found in the environment, whereas M. tuberculosis
    is found only in humans. The atypicals are also called "Mycobacteria other than
    M. tuberculosis," or MOTTS.

    The atypicals are subdivided into slow growers and rapid
    growers based on whether they form colonies in more than or less than 7 days.
    (Pigment production by the slow growers need not concern us here.)

    The following are important slow growers:



    1. Mycobacterium avium-intracellulare complex (MAC) causes
      tuberculosis-like disease, especially in immunocompromised patients, such as
      those with AIDS. It is highly antibiotic-resistant.

    2. Mycobacterium kansasii also causes tuberculosis-like
      disease but is less antibiotic-resistant than MAC.

    3. Mycobacterium marinum causes "swimming pool granuloma or
      fish tank granuloma," which is a skin lesion at the site of an abrasion acquired
      in a swimming pool or an aquarium.

    4. Mycobacterium scrofulaceum causes scrofula, which
      manifests as swollen, nontender cervical lymph nodes (cervical
      adenitis).

    The important rapid grower is Mycobacterium
    fortuitum-chelonei
    complex, which causes infections of prosthetic joints and
    indwelling catheters. It also causes skin and soft tissue infections at the site
    of puncture wounds. The organisms are usually resistant to most antituberculosis
    drugs.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Mycobacterium leprae

    Disease

    Leprosy.

    Characteristics

    Aerobic, acid-fast rods. Cannot be cultured in vitro.
    Optimal growth at less than body temperature, so lesions are on cooler parts of
    the body, such as skin, nose, and superficial nerves.

    Habitat and Transmission

    Humans are the reservoir. Also found in armadillos, but
    it's uncertain whether they are a source of infections for humans. Most
    important mode of transmission is probably nasal secretions of patients with the
    lepromatous form. Patients with the lepromatous form are more likely to transmit
    than those with the tuberculoid form because they have much higher numbers of
    organisms than those with tuberculoid leprosy. Prolonged exposure is usually
    necessary.

    Pathogenesis

    Lesions usually occur in the cooler parts of the body,
    e.g., skin and peripheral nerves. In tuberculoid leprosy, destructive lesions
    are due to the cell-mediated response to the organism. Damage to fingers is due
    to burns and other trauma, because nerve damage causes loss of sensation. In
    lepromatous leprosy, the cell-mediated response to M. leprae is lost and
    large numbers of organisms appear in the lesions and blood. No toxins or
    virulence factors are known.

    Laboratory Diagnosis

    Acid-fast rods are abundant in lepromatous leprosy, but few
    are found in the tuberculoid form. Cultures and serologic tests not done.
    Lepromin skin test is positive in the tuberculoid but not in the lepromatous
    form.

    Treatment

    Dapsone plus rifampin for the tuberculoid form. Clofazamine
    is added to that regimen for the lepromatous form or if the organism is
    resistant to dapsone. Treatment is for at least 2 years.

    Prevention

    Dapsone for close family contacts. No vaccine is
    available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Actinomyces israelii

    Disease

    Actinomycosis (abscesses with draining sinus tracts).

    Characteristics

    Anaerobic, gram-positive filamentous, branching rods.

    Habitat and Transmission

    Habitat is human mouth, especially anaerobic crevices
    around the teeth. Transmission into tissues occurs during dental disease or
    trauma. Organism also aspirated into lungs, causing thoracic actinomycosis.
    Retained intrauterine device (IUD) predisposes to pelvic actinomycosis.

    Pathogenesis

    No toxins or virulence factors known. Organism forms sinus
    tracts that open onto skin and contain "sulfur granules," which are mats of
    intertwined filaments of bacteria.

    Laboratory Diagnosis

    Gram-stained smear plus anaerobic culture on blood agar
    plate. "Sulfur granules" visible in the pus. No serologic tests.

    Treatment

    Penicillin G and surgical drainage.

    Prevention

    No vaccine or drug is
    available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Nocardia asteroides

    Disease

    Nocardiosis (especially lung and brain abscesses).

    Characteristics

    Aerobic, gram-positive filamentous, branching rods. Weakly
    acid-fast.

    Habitat and Transmission

    Habitat is the soil. Transmission is via airborne
    particles, which are inhaled into the lungs.

    Pathogenesis

    No toxins or virulence factors known. Immunosuppression and
    cancer predispose to infection.

    Laboratory Diagnosis

    Gram-stained smear and modified Ziehl-Neelsen stain.
    Aerobic culture on blood agar plate. No serologic tests.

    Treatment

    Sulfonamides.

    Prevention

    No vaccine or drug is
    available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Mycoplasma pneumoniae

    Disease

    "Atypical" pneumonia.

    Characteristics

    Smallest free-living organisms. Not seen on Gram-stained
    smear because they have no cell wall, so dyes are not retained. The only
    bacteria with cholesterol in cell membrane. Can be cultured in vitro.

    Habitat and Transmission

    Habitat is the human respiratory tract. Transmission is via
    respiratory droplets.

    Pathogenesis

    No exotoxins produced. No endotoxin because there is no
    cell wall. Produces hydrogen peroxide, which may damage the respiratory
    tract.

    Laboratory Diagnosis

    Gram stain not useful. Can be cultured on special
    bacteriologic media but takes at least 10 days to grow, which is too long to be
    clinically useful. Positive cold-agglutinin test is presumptive evidence.
    Complement fixation test for antibodies to Mycoplasma pneumoniae is more
    specific.

    Treatment

    Erythromycin or tetracycline.

    Prevention

    No vaccine or drug is
    available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Treponema pallidum

    Disease

    Syphilis.

    Characteristics

    Spirochetes. Not seen on Gram-stained smear because
    organism is too thin. Not cultured in vitro.

    Habitat and Transmission

    Habitat is the human genital tract. Transmission is by
    sexual contact and from mother to fetus across the placenta.

    Pathogenesis

    Organism multiplies at site of inoculation and then spreads
    widely via the bloodstream. Many features of syphilis are attributed to blood
    vessel involvement causing vasculitis. Primary (chancre) and secondary lesions
    heal spontaneously. Tertiary lesions consist of gummas (granulomas in bone,
    muscle, and skin), aortitis, or central nervous system inflammation. No toxins
    or virulence factors known.

    Laboratory Diagnosis

    Seen by dark-field microscopy or immunofluorescence.
    Serologic tests important: VDRL (or RPR) is nontreponemal (nonspecific) test
    used for screening; FTA-ABS is the most widely used specific test for
    Treponema pallidum. Antigen in VDRL is beef heart cardiolipin; antigen in
    FTA-ABS is killed T. pallidum. VDRL declines with treatment, whereas
    FTA-ABS remains positive for life.

    Treatment

    Penicillin is effective in the treatment of all stages of
    syphilis. In primary and secondary syphilis, use benzathine penicillin G (a
    depot preparation) because T. pallidum grows slowly, so drug must be
    present for a long time. There is no resistance.

    Prevention

    Benzathine penicillin given to contacts. No vaccine is
    available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Borrelia burgdorferi

    Disease

    Lyme disease.

    Characteristics

    Spirochetes. Gram stain not useful. Can be cultured in
    vitro, but not usually done.

    Habitat and Transmission

    The main reservoir is the white-footed mouse. Transmitted
    by the bite of ixodid ticks, especially in three areas in the United States:
    Northeast (e.g., Connecticut), Midwest (e.g., Wisconsin), and West Coast (e.g.,
    California). Eighty percent of cases are in the Northeastern states of
    Connecticut, New York, and New Jersey. Very small nymph stage of ixodid tick
    (deer tick) is most common vector. Tick must feed for at least 24 hours to
    deliver an infectious dose of B. burgdorferi.

    Pathogenesis

    Organism invades skin, causing a rash called erythema
    migrans. It then spreads via the bloodstream to involve primarily the heart,
    joints, and central nervous system. No toxins or virulence factors
    identified.

    Laboratory Diagnosis

    Diagnosis usually made serologically, i.e., by detecting
    IgM antibody. Confirm positive serologic test with Western blot assay.

    Treatment

    Doxycycline for early stages; penicillin G for late
    stages.

    Prevention

    Vaccine containing outer membrane protein of the organism
    was available but has been withdrawn. Avoid tick bite. Can give doxycycline or
    amoxicillin to people who are bitten by a tick in endemic
    areas.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Leptospira interrogans

    Disease

    Leptospirosis.

    Characteristics

    Spirochetes that can be seen on dark-field microscopy but
    not light microscopy. Can be cultured in vitro.

    Habitat and Transmission

    Habitat is wild and domestic animals. Transmission is via
    animal urine. In the United States, transmission is chiefly via dog, livestock,
    and rat urine.

    Pathogenesis

    Two phases: an initial bacteremic phase and a subsequent
    immunopathologic phase with meningitis. No toxins or virulence factors
    known.

    Laboratory Diagnosis

    Dark-field microscopy and culture in vitro are available
    but not usually done. Diagnosis usually made by serologic testing for antibodies
    in patient's serum.

    Treatment

    Penicillin G. There is no significant antibiotic
    resistance.

    Prevention

    Doxycycline effective for short-term exposure. Vaccination
    of domestic livestock and pets. Rat control.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Borrelia recurrentis

    Causes relapsing fever. Transmitted by human body louse.
    Organism well known for its rapid antigenic changes, which account for the
    relapsing nature of disease. Antigenic changes are due to programmed
    rearrangements of bacterial DNA encoding surface
    proteins.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Chlamydia trachomatis

    Diseases

    Nongonococcal urethritis, cervicitis, inclusion
    conjunctivitis, lymphogranuloma venereum, and trachoma. Also pneumonia in
    infants.

    Characteristics

    Obligate intracellular parasites. Not seen on Gram-stained
    smear. Exists as inactive elementary body extracellularly and as metabolically
    active, dividing reticulate body intracellularly.

    Habitat and Transmission

    Habitat is the human genital tract and eyes. Transmission
    is by sexual contact and during passage of neonate through birth canal.
    Transmission in trachoma is chiefly by hand-to-eye contact.

    Pathogenesis

    No toxins or virulence factors known.

    Laboratory Diagnosis

    Cytoplasmic inclusions seen on Giemsa-stained or
    fluorescent-antibody-stained smear. Glycogen-filled cytoplasmic inclusions can
    be visualized with iodine. Organism grows in cell culture and embryonated eggs,
    but these are not often used. PCR-based assay and an ELISA using patient's urine
    are available.

    Treatment

    A tetracycline (such as doxycycline) or a macrolide (such
    as azithromycin).

    Prevention

    Erythromycin effective in infected mother to prevent
    neonatal disease. No vaccine is available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Chlamydia pneumoniae

    Disease

    Atypical pneumonia.

    Characteristics

    Same as C. trachomatis.

    Habitat and Transmission

    Habitat is human respiratory tract. Transmission is by
    respiratory aerosol.

    Pathogenesis

    No toxins or virulence factors known.

    Laboratory Diagnosis

    Serologic tests for antibody in patient's serum.

    Treatment

    A tetracycline, such as doxycycline.

    Prevention

    No vaccine or drug is
    available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Chlamydia psittaci

    Disease

    Psittacosis.

    Characteristics

    Same as C. trachomatis.

    Habitat and Transmission

    Habitat is birds, both psittacine and others. Transmission
    is via aerosol of dried bird feces.

    Pathogenesis

    No toxins or virulence factors known.

    Laboratory Diagnosis

    Diagnosis usually made by testing for antibodies in
    patient's serum. Cytoplasmic inclusion seen by Giemsa or fluorescent-antibody
    staining. Organism can be isolated from sputum, but this is rarely done.

    Treatment

    Tetracycline.

    Prevention

    No vaccine or drug is
    available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Rickettsia rickettsii

    Disease

    Rocky Mountain spotted fever.

    Characteristics

    Obligate intracellular parasites. Not seen well on
    Gram-stained smear. Antigens cross-react with OX strains of Proteus
    vulgaris
    (Weil-Felix reaction).

    Habitat and Transmission

    Dermacentor (dog) ticks are both the vector and the
    main reservoir. Transmission is via tick bite. Dogs and rodents can be
    reservoirs as well.

    Pathogenesis

    Organism invades endothelial lining of capillaries, causing
    vasculitis. No toxins or virulence factors identified.

    Laboratory Diagnosis

    Diagnosis made by detecting antibody in serologic tests
    such as the ELISA test. Weil-Felix test is no longer used. Stain and culture
    rarely done.

    Treatment

    Tetracycline.

    Prevention

    Protective clothing and prompt removal of ticks.
    Tetracycline effective in exposed persons. No vaccine is
    available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Rickettsia prowazekii

    Disease

    Typhus.

    Characteristics

    Same as R. rickettsii.

    Habitat and Transmission

    Humans are the reservoir, and transmission is via the bite
    of the human body louse.

    Pathogenesis

    No toxins or virulence factors known.

    Laboratory Diagnosis

    Serologic tests for antibody in patient's serum.

    Treatment

    A tetracycline, such as doxycycline.

    Prevention

    A killed vaccine is used in the military but is not
    available for civilian use.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Coxiella burnetii

    Disease

    Q fever.

    Characteristics

    Obligate intracellular parasites. Not seen well on
    Gram-stained smear.

    Habitat and Transmission

    Habitat is domestic livestock. Transmission is by
    inhalation of aerosols of urine, feces, amniotic fluid, or placental tissue. The
    only rickettsia not transmitted to humans by an arthropod.

    Pathogenesis

    No toxins or virulence factors known.

    Laboratory Diagnosis

    Diagnosis usually made by serologic tests. Weil-Felix test
    is negative. Stain and culture rarely done.

    Treatment

    Tetracycline.

    Prevention

    Killed vaccine for persons in high-risk occupations. No
    drug is available.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Note

    Only the more important of the minor bacterial pathogens
    are summarized in this section.
    </td></tr></table>
    <table border="0" cellpadding="0" cellspacing="0">

    <tr>
    <td valign="top" bgcolor="#ffffff">Bartonella henselae
    </td></tr></table>
    //

























































      الوقت/التاريخ الآن هو الخميس ديسمبر 14, 2017 6:23 am