Rickettsiae and Chlamydia Quiz
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Questions and Answers

Which characteristic is NOT typical of Rickettsiae?

  • Transmission via arthropod vectors
  • Cultivable in basic artificial media (correct)
  • Obligate intracellular existence
  • Gram-negative coccobacilli morphology

    • What is the primary target site for Rickettsiae within the human body?

  • Neurons of the central nervous system
  • Endothelial cells lining blood vessels (correct)
  • Epithelial cells of the skin
  • Lymphatic node macrophages

    • What facilitates Rickettsiae's adhesion to endothelial cells during the infectious process?

  • Species-specific peptidoglycan
  • Alkali-stable antigens
  • Outer membrane proteins like OmpA and OmpB (correct)
  • Group-specific lipopolysaccharide (LPS)

    • How do spotted fever Rickettsiae spread from one cell to another?

    <p>Actin polymerization (B)</p> Signup and view all the answers

    Which of the following is the most accurate description of the fate of Rickettsiae once they are released from host cells?

    <p>They are unstable and die quickly (D)</p> Signup and view all the answers

    In the context of Rickettsial infection, what is the role of the outer membrane proteins (OMPs)?

    <p>Facilitating adhesion to endothelial cells (D)</p> Signup and view all the answers

    What component of the Rickettsiae cell wall is group-specific and alkali-stable?

    <p>Lipopolysaccharide (LPS) (B)</p> Signup and view all the answers

    After phagocytosis by the host cell, where do rickettsiae reside?

    <p>Inside a vacuole (D)</p> Signup and view all the answers

    What occurs approximately 12 hours post-infection during the Chlamydia lifecycle?

    <p>Elementary bodies enlarge and contain a diffuse nucleoid. (D)</p> Signup and view all the answers

    At what stage of chlamydial infection does binary fission occur?

    <p>Reticulate body (D)</p> Signup and view all the answers

    When do reticulate bodies typically reorganize to form elementary bodies in the Chlamydia lifecycle?

    <p>Between 18-24 hours of infection (A)</p> Signup and view all the answers

    Which laboratory method is a non-specific test used for rickettsial antibody detection?

    <p>Weil-Felix test (D)</p> Signup and view all the answers

    Which of the following best describes the composition of a mature inclusion body in a Chlamydia infection?

    <p>100-500 elementary bodies (D)</p> Signup and view all the answers

    What is the primary mechanism by which doxycycline treats rickettsial infections?

    <p>Inhibiting protein synthesis (C)</p> Signup and view all the answers

    Based on current taxonomic classification, which genus does C. trachomatis belong to?

    <p>Chlamydiaceae (D)</p> Signup and view all the answers

    What characterizes persistent Chlamydia infection?

    <p>Development arrested at the reticulate body stage (B)</p> Signup and view all the answers

    Which characteristic initially led scientists to believe Chlamydiae were viruses rather than bacteria?

    <p>Obligately intracellular nature (C)</p> Signup and view all the answers

    Which type of antigen determines the different serovars of Chlamydia?

    <p>Serovar-specific antigens (B)</p> Signup and view all the answers

    Which serovars of C. trachomatis are associated with trachoma?

    <p>A, B, Ba, and C (D)</p> Signup and view all the answers

    What bacterial feature is exhibited by Chlamydiae that supports their classification as bacteria rather than viruses?

    <p>The presence of 70S ribosomes (D)</p> Signup and view all the answers

    Which of the following best describes the function of the elementary body (EB) in the Chlamydiae life cycle?

    <p>Metabolically inactive, infective form (A)</p> Signup and view all the answers

    Follicular conjunctivitis and Herbert's pits are characteristic of acute infection caused by which C. trachomatis serovars?

    <p>A, B, and C (A)</p> Signup and view all the answers

    During the Chlamydiae life cycle, what cellular structure does the elementary body reside within?

    <p>Phagosome (D)</p> Signup and view all the answers

    Which of the following cell types do Chlamydiae exhibit a specific tropism for?

    <p>Squamous epithelial cells of the respiratory tract (B)</p> Signup and view all the answers

    Which of the following is the most common cause of postgonococcal urethritis (PGU)?

    <p>Chlamydia trachomatis (C)</p> Signup and view all the answers

    Chlamydophila psittaci is typically transmitted to humans through which of the following routes?

    <p>Inhalation of aerosols from avian nasal discharges (C)</p> Signup and view all the answers

    Which Chlamydia trachomatis serovars are associated with lymphogranuloma venereum (LGV)?

    <p>L1, L2, L3 (B)</p> Signup and view all the answers

    What is the most common clinical manifestation of Chlamydophila psittaci infection?

    <p>Respiratory manifestation (C)</p> Signup and view all the answers

    Which of the following diseases is strongly associated with Chlamydophila pneumoniae?

    <p>Atherosclerosis (B)</p> Signup and view all the answers

    Adult inclusion conjunctivitis caused by C. trachomatis serovars D-K can occur following?

    <p>Swimming in contaminated water (A)</p> Signup and view all the answers

    Which of the following statements regarding mycoplasmas is correct?

    <p>They can replicate on artificial culture media. (C)</p> Signup and view all the answers

    Which of the following methods is considered the 'gold standard' for Chlamydia detection in the past?

    <p>Culture (egg yolk sac &amp; cell lines) (C)</p> Signup and view all the answers

    Which characteristic distinguishes mycoplasmas from viruses?

    <p>Capacity to replicate on cell-free culture media. (A)</p> Signup and view all the answers

    What structural feature is notably absent in mycoplasmas compared to most other bacteria?

    <p>A rigid cell wall (D)</p> Signup and view all the answers

    Why are mycoplasmas generally resistant to certain antibiotics?

    <p>They lack the cellular target that the antibiotic acts upon. (B)</p> Signup and view all the answers

    Which staining method is preferred for visualizing mycoplasmas, given their poor Gram-staining characteristics?

    <p>Giem sa stain (C)</p> Signup and view all the answers

    Which of the following is a recognized mode of reproduction for mycoplasmas?

    <p>Binary Fission (A)</p> Signup and view all the answers

    Which activity is associated with Mycoplasma pneumoniae that directly contributes to damage of the host's respiratory tissue?

    <p>Production of hydrogen peroxide (B)</p> Signup and view all the answers

    What factor is least likely to facilitate the transmission of Mycoplasma pneumoniae?

    <p>Contaminated food (C)</p> Signup and view all the answers

    What is the typical incubation period for Mycoplasma pneumoniae infections?

    <p>2-4 weeks (A)</p> Signup and view all the answers

    Which laboratory method involves the use of solid medium to identify Mycoplasma colonies?

    <p>Culturing on PPLO agar (D)</p> Signup and view all the answers

    Which of the following is a common extrapulmonary manifestation of Mycoplasma infection?

    <p>Septic arthritis (D)</p> Signup and view all the answers

    What is the primary method for treating Mycoplasma infections?

    <p>Macrolides (C)</p> Signup and view all the answers

    Which of the following symptoms is NOT typically associated with Mycoplasma pneumonia?

    <p>Skin rashes (C)</p> Signup and view all the answers

    Which antibody detection method is considered non-specific for diagnosing Mycoplasma infections?

    <p>Cold agglutination test (B)</p> Signup and view all the answers

    Flashcards

    Rickettsiae

    Small, non-motile, obligate intracellular gram-negative coccobacilli.

    Obligate Intracellular Organisms

    Organisms that can only grow inside host cells.

    Transmission Vectors

    Rickettsiae are transmitted via arthropods like ticks and lice.

    Typhus group

    A group of Rickettsiae associated with typhus fever.

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    Outer Membrane Proteins (OMP)

    Specific proteins on the surface of Rickettsiae aiding adhesion.

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    Endothelial Cells

    Cells lining blood vessels that Rickettsiae target.

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    Cell-to-Cell Spread

    How spotted fever rickettsiae move between host cells.

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    Release and Instability

    Rickettsiae die quickly once released from the host cell.

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    Serology

    A laboratory test for antibody detection in serum.

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    Weil Felix test

    A non-specific test detecting Rickettsial antibodies.

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    Doxycycline

    The drug of choice for treating most rickettsial illnesses.

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    Chlamydiae

    Obligate intracellular bacteria causing various diseases in humans.

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    Characteristics of Chlamydiae

    Chlamydiae have DNA/RNA, are filterable, and multiply by binary fission.

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    Life Cycle of Chlamydiae

    Has two forms: elementary body (EB) and reticulate body (RB).

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    Intracellular survival

    Elementary bodies reside in phagosomes to complete growth cycle.

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    Taxonomy of Chlamydiaceae

    Recent genetic classification changes affecting medical species like C.trachomatis.

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    Peribronchial pneumonia

    A type of pneumonia characterized by wheeze, dry cough, and thickened bronchial markings.

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    Extrapulmonary manifestations

    Rare complications from Mycoplasma infection, including conditions like Guillain-Barre syndrome.

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    Antigen detection methods

    Techniques used to identify specific antigens, such as Direct IF and ELISA.

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    Molecular methods

    Techniques that detect Mycoplasma DNA, such as 16SrRNA and Pladhesin gene detection.

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    Macrolides

    The preferred treatment for Mycoplasma infections, like azithromycin.

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    Reticulate Bodies

    Enlarged elementary bodies containing diffuse nucleoid formed by 12 hours of infection.

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    Binary Fission

    Process by which reticulate bodies start dividing within 18 hours of infection.

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    Inclusion Body

    Vacuoles that expand to form inclusion bodies, detectable by histologic stains.

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    Elementary Bodies

    Small forms of Chlamydia released from host cells, formed by 18-24 hours post-infection.

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    Persistent Infection

    When development halts at the reticulate body stage, leading to a latent infection.

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    Chlamydia Trachomatis

    A human pathogen causing ocular, urogenital, and neonatal infections.

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    Trachoma

    Chronic keratoconjunctivitis caused by C. trachomatis serovars A, B, C, primarily affecting children.

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    Nongonococcal Urethritis (NGU)

    The most common infection caused by C. trachomatis, responsible for 30-50% cases.

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    Mycoplasma Characteristics

    Bacteria that are filterable, pleomorphic, and lack a rigid cell wall.

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    Mycoplasma pneumoniae

    Causative agent of primary atypical pneumonia in humans.

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    Pathogenesis Steps

    Attachment to respiratory mucosa followed by tissue injury via toxins.

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    Infection Transmission

    Mycoplasma pneumoniae spreads through respiratory droplets.

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    Clinical Manifestations

    Includes upper respiratory infections and atypical pneumonia.

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    Epidemiology

    Infections are endemic with periodic epidemics every 4-7 years.

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    Giemsa Stain

    Used to stain Mycoplasma which are poorly gram-negative.

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    Host Response

    Mycoplasma membrane antigens trigger an immune response.

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    Postgonococcal Urethritis (PGU)

    Urethritis in men caused by C.trachomatis, occurring 2-3 weeks after gonorrhea recovery.

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    Chlamydia Epididymitis

    Epididymitis in males mostly caused by C.trachomatis.

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    Inclusion Conjunctivitis

    Ocular infection caused by C.trachomatis in adults and newborns.

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    Lymphogranuloma Venereum (LGV)

    Infection by C.trachomatis serovars L1, L2, and L3.

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    Psittacosis

    Infection caused by C.psittaci, often from infected birds.

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    Chlamydophila pneumoniae

    Human pathogen causing atypical pneumonia and associated with atherosclerosis.

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    Chlamydial Diagnosis Techniques

    Laboratory methods include microscopy, antigen detection, culture, and NAAT.

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    Study Notes

    Rickettsiae

    • Rickettsiae are a group of small, non-motile, gram-negative coccobacilli.
    • They are obligate intracellular organisms.
    • They are not cultivable in artificial media but can grow in cell lines or by animal and egg inoculation.
    • Transmission is via arthropods such as ticks, mites, fleas, or lice.
    • Rickettsia species are categorized into two groups based on clinical manifestations: Typhus group and Spotted fever group.
    • Cell walls are similar to gram-negative bacteria, comprising peptidoglycan, lipopolysaccharide, and an outer membrane with few outer membrane proteins.
    • Species-specific outer membrane proteins (OMP) and group-specific alkali-stable lipopolysaccharide (LPS) antigen are present.
    • Pathogenesis involves transmission by arthropods, spread through lymphatics, multiplication in lymph nodes, and dissemination via bloodstream.
    • Target site is endothelial cells.
    • Phagocytosis is mediated by OmpA and OmpB, leading to phagocytosis.
    • Multiplication is slow, by binary fission within host cells.
    • Spotted fever rickettsiae spread cell-to-cell via actin polymerization.
    • Other rickettsiae accumulate until host cell lysis.
    • Reason for obligate intracellular survival isn't understood.
    • Endothelial cell injury occurs via lipid peroxidation.
    • Bacteria released from host cells are unstable and quickly die.

    Chlamydiae

    • Chlamydiae are obligate intracellular bacteria causing various diseases in humans.
    • These include trachoma, lymphogranuloma venereum (LGV), conjunctivitis, pneumonia, and psittacosis.
    • They also cause widespread diseases in birds and mammals.
    • Chlamydiae are bacteria, not viruses, though they have some similar properties.
    • They are obligately intracellular organisms and can't be cultured in artificial media but can in cell lines, embryonated eggs, or animals.
    • They are filterable, small enough to pass through bacterial filters.
    • Chlamydiae produce intracytoplasmic inclusions.
    • Chlamydiae have DNA and RNA, gram-negative cell wall, binary fission, 70 S prokaryotic ribosomes, synthesize nucleic acids, lipids, and proteins and are susceptible to antibiotics.
    • Chlamydiae exist in two forms: elementary bodies (EB) and reticulate bodies (RB).
    • They have specific tropism for squamous epithelial cells and macrophages in the respiratory tract.
    • The life cycle involves attachment, intracellular survival, transformation to reticulate bodies, replication, transformation back to elementary bodies, inclusion body formation, and release.
    • The inclusion body formation gradually increases in size and is detected by histologic stains.
    • Mature inclusion bodies contain approximately 100-500 elementary bodies that are ultimately released from host cells within 48 hours.
    • Pathogenic species are C. trachomatis and C. psittaci, which are categorized based on genetic characteristics.
    • C. trachomatis serovars include A, B, Ba, C (trachoma), D-K (genital infections and inclusion conjunctivitis) and L1-L3 (LGV).
    • C. psittaci is a pathogen of parrots and other psittacine birds, causing psittacosis, with transmission via inhalation of aerosols and direct contact with birds.
    • Clinical manifestations in C. psittaci include, an incubation period of 5-19 days and respiratory, septicemia, gastrointestinal, and typhoid-like syndrome.
    • Serovars A, B, Ba, and C cause trachoma in humans.

    Chlamydia trachomatis (Specific)

    • Chlamydia trachomatis is primarily a human pathogen causing ocular, urogenital, and neonatal infections.
    • 18 serovars have been identified affecting humans.
    • Serovars A, B, Ba, and C are linked to ocular disease (trachoma).
    • Serovars D-K are associated with genital diseases, including infection of newborns.
    • Serovars L1-L3 cause lymphogranuloma venereum (LGV).

    Chlamydia pneumoniae (Specific)

    • C. pneumoniae is an exclusively human pathogen.
    • It is an atypical pneumonia.
    • Atherosclerosis, bronchial asthma, and COPD can be linked to C. pneumoniae infection.

    Mycoplasma

    • Mycoplasmas are the smallest free-living microbes in the environment.
    • They self-replicate on artificial culture media.
    • They are smaller than 150-350 μm, and filterable through bacterial filters.
    • They differ from viruses by being free-living in the environment and growing in artificial cell-free culture media.
    • They lack a rigid cell wall and are highly pleomorphic (coccoid, bacillary, filamentous, or helical).
    • They are poorly Gram-negative and better stained by Giemsa stain.
    • Mycoplasmas reproduce via binary fission and budding.
    • They are non-sporing and non-flagellated.
    • They are sometimes contaminants in cell cultures.
    • Mycoplasma pathogenic species include M. pneumoniae and others causing genital tract infections (M. hominis, M. genitalium).
    • Pathogenesis of M. pneumoniae involves attachment to respiratory mucosa, host injury (hydrogen peroxide, cytotoxin, lipoprotein), and infections.

    Mycoplasma Pneumoniae (Specific)

    • M. pneumoniae is the causative agent of primary atypical pneumonia.
    • Mycoplasma possesses several cell membrane antigens which play a role in initiating a host response to infection (glycolipid and membrane-bound proteins).
    • Symptoms of infection may manifest within 2-4 weeks following exposure. Clinical presentations include upper respiratory infections, pneumonia, and extrapulmonary manifestations.
    • Diagnosis involves identification of specific antigens and antibodies for mycoplasma infection.
    • Methods of treatment are effective, focusing on antibiotic resistance (macrolides and alternative drugs).

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    Description

    Test your knowledge on the characteristics, infection processes, and lifecycle of Rickettsiae and Chlamydia. This quiz covers key concepts including cellular adhesion, lifecycle stages, and laboratory detection methods. Perfect for students studying microbiology or infectious diseases.

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