Introduction to Human Pathogenic Bacteria: Extracellular vs Intracellular Lifecycle

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What protects intracellular pathogens from humoral antibodies?

Effector proteins

Membrane-disrupting enzymes

Cellular immune response (correct)

Specialized mechanisms

Which type of pathogens can only reproduce inside host cells?

Listeria monocytogenes

Salmonella spp.

Mycobacterium leprae (correct)

Legionella pneumophila

What is the purpose of exoenzymes produced by pathogens during invasion?

To trigger an immune response

To facilitate colonization of host tissues (correct)

To destroy host cells

To neutralize lysosomal enzymes

Which bacteria exploit nutrients in the host cell during their intracellular 'lifestyle'?

Chlamydia spp. Signup and view all the answers

What is a characteristic feature of facultative intracellular pathogens?

They can reproduce both inside and outside of host cells. Signup and view all the answers

Which mechanism allows Listeria monocytogenes to spread from one host cell to another?

Replication in the host cell cytosol Signup and view all the answers

What is a characteristic feature of obligate intracellular bacteria mentioned in the text?

Requirement of viable eukaryotic host cells for growth Signup and view all the answers

What is the role of the pore-forming toxin LLO in the context of Listeria infection?

Facilitates escape from the phagosome Signup and view all the answers

Which bacterium is mentioned as an example of an obligate intracellular pathogen in the text?

Coxiella burnetii Signup and view all the answers

What is the primary action of chlamydial elementary bodies (EB) upon attachment to epithelial cells?

Prevent fusion of phagosome with host lysosome Signup and view all the answers

What is the primary function of effector proteins secreted by certain pathogens during invasion into host cells?

Trigger entry into host cell Signup and view all the answers

Which bacterial mechanism of invasion relies on surface proteins binding to receptors on host cell membranes?

Zipper mechanism Signup and view all the answers

What is the significance of avoiding the microbicidal lysosome for intracellular survival strategies of pathogens?

To subvert endosomal trafficking Signup and view all the answers

Which bacterial pathogen utilizes effector molecules to cause membrane ruffles in the process of membrane ruffling during invasion?

Salmonella Signup and view all the answers

What is a common strategy used by intracellular pathogens to enhance protection against immune recognition?

Remodeling of the vacuole Signup and view all the answers

How do Mycobacterium tuberculosis, Legionella pneumophila, and Salmonella species evade being digested by the phagocyte?

Prevent fusion of phagosome with lysosome and remain alive and dividing within the phagosome Signup and view all the answers

What is the mechanism used by Salmonella to evade the host's immune system after entering macrophages?

Prevent fusion of the phagosome with the lysosome and proliferate within the SCV Signup and view all the answers

How do L.monocytogenes and Shigella escape the phagosome and multiply within the cytoplasm?

Prevent lysis of the phagosome to maintain intracellular survival Signup and view all the answers

What is the main strategy used by intracellular pathogens like Mycobacterium tuberculosis to survive within phagocytes?

Prevent fusion of phagosome with lysosome and remain alive within it Signup and view all the answers

How does Legionella pneumophila differ in its intracellular survival strategy compared to Mycobacterium tuberculosis?

Legionella pneumophila prevents lysis of the phagosome for intracellular survival Signup and view all the answers

Which term describes the Coxiella burnetii compartment where it replicates inside alveolar macrophages?

Coxiella-containing vacuole (CCV) Signup and view all the answers

Which of the following is NOT an obligate intracellular bacteria from the Rickettsiales group mentioned in the text?

Streptococcus pyogenes Signup and view all the answers

What is the degradative pathway involving lysosomes and cytosolic content that plays a role in cellular homeostasis and innate immunity?

Autophagy Signup and view all the answers

Which bacterial pathogen uses ActA, Phospholipase C, and Autolysosome for intracellular survival and replication?

Listeria monocytogenes Signup and view all the answers

What factor explains the limited niche for bacterial replication in different cell types due to the failure of bacteria to use cytosolic substrates?

Bacterial tropism Signup and view all the answers

What is a common strategy employed by intracellular pathogens to resist being destroyed inside host cells?

Preventing phagolysosome fusion Signup and view all the answers

Which category of bacteria is likely to possess effector proteins that aid in invasion of host cells?

Obligate intracellular bacteria Signup and view all the answers

Phagosomal membrane disruption is a critical step for some pathogens to survive intracellularly. Which mechanism is commonly employed for this disruption?

Interference with actin polymerization Signup and view all the answers

Intracellular survival mechanisms often involve acquiring nutrients within host cells. What is a typical nutrient source for these bacteria?

Host cell cytoplasm Signup and view all the answers

Obligate intracellular bacteria have specialized adaptation for survival. Which of these characteristics is typically associated with this group of pathogens?

Dependence on host cells for replication Signup and view all the answers

What is the role of haemolysin C and phospholipases in the escape strategy of Rickettsia prowazekii?

Disrupting the vacuolar membrane Signup and view all the answers

What is a common feature of cytosolic pathogens during cell-to-cell spread?

Enclosed in a secondary double-membrane vacuole Signup and view all the answers

Why do cytosolic bacteria polymerize actin at the bacterial pole?

For intracellular and intercellular motility Signup and view all the answers

What is the immediate result of bacteria entering the host cell in a primary vacuole?

Secretion of bacterial escape proteins Signup and view all the answers

Which step follows bacterial internalization in a secondary vacuole during cell-to-cell spread?

Disruption of double-membrane vacuole membranes Signup and view all the answers

What is the significance of bacteria being free in the cytosol for obligate intracellular pathogens?

It signifies escape from host cell vacuoles Signup and view all the answers

How do bacteria facilitate their entry into host cells during the initial stages of infection?

Through secretion of bacterial escape proteins Signup and view all the answers