Bacteriology exam prep: Intracellular Bacteria: Chlamydiaceae, Coxiella, Rickettsiales, Anaplasma, Ehrlichia, Lawsonia intracellularis
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Questions and Answers

What is the initial form of Chlamydia that attaches and enters the host cell?

  • Aberrant body
  • Inclusion membrane protein
  • Elementary body (correct)
  • Reticulate body

    • What state do reticulate bodies enter under stress-inducing conditions?

  • Aberrant body (correct)
  • Elementary body
  • Trophozoite
  • Larval state

    • Which species of Chlamydia is associated with economically significant infections in sheep and goats?

  • Chlamydia abortus (correct)
  • Chlamydia suis
  • Chlamydia pecorum
  • Chlamydia psittaci

    • How long does it take for reticulate bodies to differentiate back into elementary bodies?

    <p>20-44 hours</p> Signup and view all the answers

    Which effector protein is involved in the prevention of lysosomal fusion with the inclusion vacuole?

    <p>Inclusion membrane proteins</p> Signup and view all the answers

    What is the primary cause of tissue damage in chlamydial infections?

    <p>Host inflammatory response</p> Signup and view all the answers

    How often do reticulate bodies replicate by binary fission?

    <p>Every 2 to 3 hours</p> Signup and view all the answers

    Which pathogen transmission route is most associated with Chlamydia abortus in sheep and goats?

    <p>Oronasal route</p> Signup and view all the answers

    What major impact does the nuclear membrane targeting effector protein have on the host cell?

    <p>It interferes with lamins at the host cell nuclear membrane</p> Signup and view all the answers

    What mechanism allows Chlamydia to survive for long periods under unfavorable growth conditions?

    <p>Chlamydial persistence</p> Signup and view all the answers

    Which of the following is a characteristic of Chlamydia spp.?

    <p>They are obligate intracellular bacteria.</p> Signup and view all the answers

    Which staining method is commonly used for Chlamydia spp.?

    <p>Giemsa staining</p> Signup and view all the answers

    Which two Chlamydia species are specifically noted as human pathogens?

    <p>Chlamydia trachomatis and Chlamydia pneumoniae</p> Signup and view all the answers

    What is the primary transmission route for Chlamydia spp.?

    <p>Fecal-oral route</p> Signup and view all the answers

    Which Chlamydia species causes disease that is difficult to distinguish from Mycoplasma infections based on clinical symptoms alone?

    <p>All mentioned species</p> Signup and view all the answers

    Which habitat do Chlamydia spp. primarily infect in their hosts?

    <p>Epithelial cells and mucous membranes</p> Signup and view all the answers

    How many characterized species of the genus Chlamydia are recognized?

    <p>15</p> Signup and view all the answers

    Chlamydia spp. displays a preference for which part of their host?

    <p>Gastrointestinal tract</p> Signup and view all the answers

    What type of envelope do Chlamydia spp. have?

    <p>Composed of proteins and lipopolysaccharides</p> Signup and view all the answers

    Which secretion method is not mentioned for Chlamydia shedding in symptomatic or asymptomatic animals?

    <p>Shed in saliva and sweat</p> Signup and view all the answers

    What is a significant zoonotic concern because of its low infectious dose and aerosol transmission in ruminants?

    <p>C. burnetii</p> Signup and view all the answers

    What is the minimum infectious dose of inhaled C. burnetii bacteria to humans?

    <p>1-10 bacteria</p> Signup and view all the answers

    In which phase of its developmental lifecycle does C. burnetii undergo exponential replication?

    <p>Four days after infection</p> Signup and view all the answers

    Which morphological form of C. burnetii is metabolically dormant and spore-like?

    <p>SCV</p> Signup and view all the answers

    In what kind of environment does C. burnetii survive and require for initiating intracellular replication?

    <p>Acidic environment</p> Signup and view all the answers

    Which family under the order Rickettsiales includes the genera Ehrlichia and Anaplasma?

    <p>Anaplasmataceae</p> Signup and view all the answers

    How are the majority of organisms in the order Rickettsiales transmitted?

    <p>By arthropod vectors</p> Signup and view all the answers

    Which Rickettsiales genus is transmitted through ingestion of infected trematodes?

    <p>Neorickettsia</p> Signup and view all the answers

    What common symptom is exhibited by around 50% of people infected with C. burnetii?

    <p>No clinical signs or mild self-limiting infection</p> Signup and view all the answers

    Which pathogen primarily replicates within a phagosome of a macrophage after gaining access through inhalation or tick bite?

    <p>C. burnetii</p> Signup and view all the answers

    Which avian species has the highest prevalence of Chlamydia psittaci infection?

    <p>Psittacine birds</p> Signup and view all the answers

    What is a common route of transmission for Chlamydia psittaci between birds?

    <p>Inhalation of the respiratory exudate</p> Signup and view all the answers

    Which symptom is NOT commonly associated with Chlamydia felis infection in cats?

    <p>Paralysis</p> Signup and view all the answers

    How can humans become infected with Chlamydia psittaci?

    <p>Inhalation of aerosolized bacteria</p> Signup and view all the answers

    What kind of disease presentation is least likely to be caused by Chlamydia psittaci in birds?

    <p>Paralysis</p> Signup and view all the answers

    In which bodily secretion is Chlamydia felis most commonly found in cats?

    <p>Ocular and oronasal secretions</p> Signup and view all the answers

    Which condition is NOT associated with Chlamydia psittaci infection in birds?

    <p>Diabetes</p> Signup and view all the answers

    Which statement best describes Chlamydia felis infection in cats?

    <p>It leads to acute to chronic unilateral or bilateral conjunctivitis.</p> Signup and view all the answers

    Which birds are most likely to shed Chlamydia psittaci persistently?

    <p>Asymptomatic carriers</p> Signup and view all the answers

    Which disease is caused by Coxiella burnetii?

    <p>Q fever</p> Signup and view all the answers

    What is the primary target of intracellular infection in R.rickettsii infection?

    <p>Endothelium</p> Signup and view all the answers

    What is the main clinical manifestation of R.rickettsii infection in dogs?

    <p>Fever and depression</p> Signup and view all the answers

    What is the mechanism by which Lawsonia intracellularis infects epithelial cells?

    <p>Prevents immature cell differentiation</p> Signup and view all the answers

    What is the source of infection for susceptible pigs?

    <p>Feces from infected pigs</p> Signup and view all the answers

    What is the outcome of proliferative enteropathy in pigs?

    <p>Acute hemorrhagic diarrhea</p> Signup and view all the answers

    What is the characteristic of the acute form of porcine proliferative enteropathy?

    <p>Thickened and turgid intestines with a corrugated serosal surface</p> Signup and view all the answers

    What is the outcome of mucosal destruction in proliferative enteropathy?

    <p>Rapid death of animals</p> Signup and view all the answers

    What is the role of intestinal microbiota in Lawsonia intracellularis infection?

    <p>Modifies the ability of L.intracellularis to colonize the intestinal tract</p> Signup and view all the answers

    What is the outcome of R.rickettsii infection in the lungs?

    <p>Interstitial pneumonia</p> Signup and view all the answers

    What is the result of endothelial injury in R.rickettsii infection?

    <p>All of the above</p> Signup and view all the answers

    In animals infected with Anaplasma marginale, what is the primary location of the pathogen within erythrocytes?

    <p>marginal inclusion bodies</p> Signup and view all the answers

    What is the primary vertebrate reservoir of Anaplasma phagocytophilum?

    <p>white-footed mouse</p> Signup and view all the answers

    What is the characteristic of Anaplasma phagocytophilum infections in all hosts?

    <p>thrombocytopenia</p> Signup and view all the answers

    In which stage of infection are morulae detected in the cytoplasm of granulocytes?

    <p>early clinical phase</p> Signup and view all the answers

    What is the primary tick vector for Anaplasma platys infections?

    <p>Rhipicephalus sanguineus</p> Signup and view all the answers

    What is the characteristic of Anaplasma platys infections in dogs?

    <p>cyclic thrombocytopenia</p> Signup and view all the answers

    What is the primary transmission route for Ehrlichia species?

    <p>tick transmission</p> Signup and view all the answers

    What is the common clinical sign exhibited by dogs infected with Anaplasma platys?

    <p>all of the above</p> Signup and view all the answers

    What is the age group of cattle most likely to result in mortalities up to 30-50% due to Anaplasma marginale infections?

    <p>3 years or more</p> Signup and view all the answers

    What is the characteristic of Anaplasma phagocytophilum infections in ruminants?

    <p>vascular changes in the testes and ovaries</p> Signup and view all the answers

    What is the initial form of Ehrlichiae that attaches to the host cell?

    <p>DC ehrlichia</p> Signup and view all the answers

    In the acute phase of E. canis infection in dogs, which laboratory abnormality is typically detected?

    <p>Thrombocytopenia</p> Signup and view all the answers

    Which of the following accurately describes a method by which DC ehrlichiae are released from the host cell?

    <p>Host cell lysis</p> Signup and view all the answers

    Which phase of E. canis infection is characterized by severe pancytopenia and poor prognosis?

    <p>Chronic phase</p> Signup and view all the answers

    What biologically active ingredient in arthropod saliva helps transmit rickettsiae?

    <p>Hemostatic inhibitors</p> Signup and view all the answers

    Which rickettsial species is known to be highly pathogenic for certain inbred breeds of dogs?

    <p>R. rickettsii</p> Signup and view all the answers

    What is a distinguishing feature of the DC form of Ehrlichia?

    <p>Coccoid shape</p> Signup and view all the answers

    What pathology is common in the chronic phase of E. canis infection in dogs?

    <p>Bone marrow hypoplasia</p> Signup and view all the answers

    How do spotted fever group rickettsiae move within host cells?

    <p>Actin-based mobility</p> Signup and view all the answers

    What characterizes the subclinical phase of E. canis infection?

    <p>Absence of clinical signs but detectable laboratory anomalies</p> Signup and view all the answers

    Which Anaplasma species is primarily associated with infections in canine hosts?

    <p>Anaplasma platys</p> Signup and view all the answers

    What cell type is primarily targeted by Anaplasma phagocytophilum?

    <p>Granulocytes</p> Signup and view all the answers

    Which tick genus is responsible for transmitting Anaplasma marginale in North America?

    <p>Dermacentor</p> Signup and view all the answers

    What is a major clinical consequence of bovine anaplasmosis caused by Anaplasma marginale?

    <p>Erythrocyte reduction</p> Signup and view all the answers

    Which mode of transmission contributes significantly to the spread of Anaplasma marginale?

    <p>Biting flies</p> Signup and view all the answers

    What process does Anaplasma marginale use to enter erythrocytes?

    <p>Endocytosis</p> Signup and view all the answers

    What type of disease is caused by Anaplasma ovis?

    <p>Ovine anaplasmosis</p> Signup and view all the answers

    In which type of cells does Anaplasma marginale replicate?

    <p>Phagosome</p> Signup and view all the answers

    What is the primary manifestation of severe anemia caused by Anaplasma marginale infection?

    <p>Myocardial hypoxia</p> Signup and view all the answers

    Which species acts as the reservoir host for Anaplasma marginale?

    <p>Cattle</p> Signup and view all the answers

    Study Notes

    Chlamydia

    • Chlamydiaceae are globally recognized as important veterinary and human pathogens, infecting a wide range of hosts, including humans.
    • They are obligate, intracellular pathogenic bacteria that survive and multiply only inside a host cell.
    • They are Gram-negative, but lack the typical peptidoglycan layer found in most bacterial cell walls.
    • The cell envelope is composed of proteins and lipopolysaccharides.
    • Chlamydia spp. cannot be cultivated with standard laboratory methods and require special stains like Giemsa or other polychromatic stains.

    Genus Chlamydia

    • There are 15 characterized species of Chlamydia.
    • Almost all members are globally recognized as major veterinary pathogens, with several spilling over to humans.
    • Five major pathogens are: Chlamydia psittaci, Chlamydia abortus, Chlamydia pecorum, Chlamydia trachomatis (human pathogen), and Chlamydia pneumoniae (human pathogen).

    Infections and Transmission

    • Chlamydia infections are intracellular and do not have a free-living or environmental reservoir.
    • They cannot survive outside of the host cell for extended periods.
    • Infections occur in target tissue and cause diseases similar to Mycoplasma species.
    • Natural habitat is the gastrointestinal tract, with continuous fecal shedding.
    • Transmission occurs through the fecal-oral route, inhalation of droplets, and interpersonal contact.

    Life Cycle

    • The life cycle is biphasic, alternating between the elementary body (infectious form) and the reticulate body (replicating form).
    • The cycle begins with attachment and entry of the elementary body into the host cell.
    • Inside the cell, the elementary body differentiates into a reticulate body, which replicates by binary fission.
    • The reticulate body then differentiates back into an elementary body, which is released to infect neighboring cells.

    Virulence Factors and Pathogenesis

    • The most important virulence factor is the Type III Secretion System (T3SS).
    • T3SS allows for effector protein translocation into host cells, manipulating the inclusion vacuole.
    • Effector proteins target the host cell's nuclear membrane, impacting apoptosis and promoting host cell survival.
    • Chlamydia exits the host cell by lysis or the extrusion of the inclusion vacuole, causing tissue damage.

    Pathogenic Species and Caused Diseases

    • Chlamydia abortus causes enzootic abortion in ewes, an economically important disease in sheep.
    • Infections can remain latent and asymptomatic until pregnancy, when the organism invades the placenta and causes abortion.
    • The disease can result in "storms of abortion" when new introductions or primiparous ewes enter the flock.
    • C. abortus infections also occur in cattle, pigs, deer, horses, and other animals, and present a zoonotic risk to humans, particularly pregnant women.

    Chlamydia psittaci

    • Avian chlamydial infections and disease are primarily caused by C. psittaci, but other avian species also have pathogenic potential.
    • C. psittaci is globally disseminated with a broad avian host range, infecting over 500 avian species, with highest prevalence in pigeons and psittacine birds.
    • In avian hosts, C. psittaci infections may vary from subclinical with persistent organism shedding to severe acute disease.
    • Disease presentations in affected birds include wasting, lethargy, air sacculitis, hepatitis, pericarditis, conjunctivitis, and respiratory symptoms.

    Chlamydia felis

    • C. felis is an important pathogen causing acute to chronic unilateral or bilateral conjunctivitis, rhinitis, and respiratory disease in cats.
    • Bacterial transmission between cats typically occurs by direct contact of infectious materials, particularly ocular and oronasal secretions.
    • C. felis primarily infects the conjunctival epithelium and causes acute to chronic or recurrent mucoid/mucopurulent to follicular conjunctivitis and rhinitis.

    Coxiella burnetii

    • C. burnetii is a gram-negative obligate intracellular pathogenic bacterium, which causes coxiellosis or Q fever.
    • In animals, C. burnetii is a significant cause of abortion and reduced reproductive capacity, which is also an important zoonotic concern.
    • C. burnetii causes a zoonotic human infection termed Q fever, with a worldwide distribution and found in a wide array of domesticated and wild animals.
    • Transmission occurs through ticks, inhalation of contaminated aerosols, and aerosol transmission.
    • C. burnetii has a biphasic developmental lifecycle involving two morphological forms: the replicative large-cell variant (LCV) and the metabolically dormant, spore-like small cell variant (SCV).
    • SCV are internalized and converted to LCV in about two days, with exponential replication of LCVs occurring around four days post-infection.
    • C. burnetii survives a degradative lysosomal environment and requires it to initiate intracellular replication.

    Rickettsiales

    • The order Rickettsiales is composed of two families: Anaplasmataceae (Anaplasma, Ehrlichia, Neorickettsia) and Rickettsiaceae (Rickettsia).
    • Rickettsiales are gram-negative, obligately intracellular bacteria transmitted by arthropod vectors.
    • They cause many important life-threatening infections in livestock and companion animals and emerging zoonoses in humans.

    Anaplasma

    • Anaplasma species cause severe diseases in animals, which can also be potentially fatal.
    • They trigger immune activation leading to hypersensitivity reactions and impair host defense mechanisms.
    • Anaplasma species mostly infect blood cells, erythrocytes, neutrophils, or platelets, and severely impair host defense mechanisms.
    • They replicate by binary fission within the phagosome of an infected eukaryotic cell, requiring host nutrient support.
    • All known pathogenic Anaplasma species are transmitted by ixodidae hard ticks.
    • Anaplasma species have surface-expressed proteins that function as adhesion molecules.
    • Once inside a cell, anaplasmas alter post-translation protein modifications and gene expression to support their growth and replication.

    Anaplasma Species

    • Anaplasma marginale and A. centrale are primary pathogens of cattle, infecting erythrocytes and causing bovine anaplasmosis.
    • A. ovis infects erythrocytes and causes ovine anaplasmosis.
    • A. phagocytophilum infects granulocytes in various vertebrates, including cattle, horses, dogs, cats, and humans, causing diseases such as equine anaplasmosis, bovine granulocytic anaplasmosis, and human granulocytic anaplasmosis.
    • A. platys infects thrombocytes and causes cyclic thrombocytopenia in canines.

    Anaplasma marginale (Bovine Anaplasmosis)

    • A. marginale is a major economically important disease of cattle in the US and worldwide, causing mortality and morbidity.
    • The pathogen is maintained in infected hosts, which also act as reservoirs of infection.
    • Diverse clinical manifestations occur, including anemia, fever, increased heartbeat, anorexia, depression, constipation, abortion, muscle weakness, myocardial hypoxia, and diarrhea.
    • In severe cases, animals may exhibit spikes of fever, lethargy, inappetence, pale mucous membranes, anemia, and jaundice, and may progress to a fatal outcome.
    • The clinical disease spectrum varies depending on the age of animals and strain of the pathogen.

    Anaplasma phagocytophilum

    • A. phagocytophilum infects a wide range of hosts, including horses, cattle, humans, dogs, and cats.
    • Infections are primarily reported in the US, Europe, and East Asia.
    • The disease is transmitted by ticks, such as Ixodes scapularis, I. pacificus, I. ricinus, and I. persulcatus, and the primary vertebrate reservoir is the white-footed mouse (Peromyscus leucopus).
    • Clinical symptoms include fever, depression, increased heart rate, decline of appetite, anemia, icterus, and ataxia, with ataxia more common in horses.

    Anaplasma platys

    • A. platys primarily infects canines, causing cyclic thrombocytopenia.
    • Infections are documented globally, and the tick vector is likely the brown dog tick (Rhipicephalus sanguineus).
    • Clinical signs include fever, anorexia, weakness, anemia, lethargy, eye discharge, spot hemorrhage on the eye, oral mucosa, and skin, respiratory distress, lymphadenomegaly, epistaxis, splenomegaly, and muzzle hyperkeratosis.

    Ehrlichia

    • Ehrlichia species are tick-transmitted, obligately intracellular bacteria, and are etiologic agents of important veterinary diseases, such as canine monocytic ehrlichiosis (CME).
    • Ehrlichia spp. are transmitted by ticks, including Amblyomma, Dermacentor, Ixodes, and Rhipicephalus spp.
    • Ehrlichia spp. infect mononuclear phagocytes in dogs, replicating in membrane-bound vacuoles forming microcolonies (morulae).
    • The clinical course of E. canis infection has been well documented, consisting of acute, subclinical, and chronic phases.

    Rickettsia

    • Rickettsia species are obligately intracellular organisms, including pathogens that are transmitted by ticks, fleas, mites, and lice.
    • Rickettsia rickettsii, R. conorii, R. typhi, R. prowazekii, and R. africae are known to infect animal reservoirs, but only R. rickettsii, R. typhi, and R. conorii have been well documented to cause clinical disease in dogs.
    • Rickettsia rickettsii is highly pathogenic for some inbred breeds of dogs and can reside in a zoonotic cycle involving dogs and the brown dog tick (Rhipicephalus sanguineus) or Amblyomma aureolatum.
    • Clinical manifestations of R. rickettsii infection in dogs include fever, depression, anorexia, lymph node enlargement, subcutaneous edema, muscle and joint pain, and petechiation of the skin and mucous membranes.

    Lawsonia intracellularis

    • Lawsonia intracellularis is the sole species in the genus Lawsonia, and is the etiologic agent of proliferative enteropathy, an infectious, intestinal hyperplastic disease.
    • L. intracellularis is a small, gram-negative, obligately intracellular, curved-shaped bacterium found in the apical cytoplasm of infected enterocytes.
    • The disease has been reported in a broad range of hosts, including pigs, non-human primates, hamsters, rabbits, rats, guinea pigs, foals, sheep, white-tailed deer, ferrets, arctic foxes, dogs, and certain birds.
    • The source of infection for these animal species has not been determined, but it may be endemic in certain species, or present in the environment.

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    Description

    This quiz covers the characteristics and features of Chlamydiaceae, a family of obligate intracellular pathogenic bacteria that infect a wide range of hosts, including humans. Learn about their unique cell envelope composition and Gram-negative properties.

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