BP: Mycobacterium, Bacteriophage + Microbiome

Mycobacterium

Acid-fast, slow-growing intracellular bacteria with mycolic acid-rich cell walls

What disease does Mycobacterium tuberculosis cause?

Tuberculosis

What disease does Mycobacterium leprae cause?

Leprosy

What host cell first takes up MTB in the lung?

Alveolar macrophage

What key intracellular survival strategy does MTB use?

It blocks phagosome-lysosome fusion

What secretion system is important in MTB virulence?

ESX-1

What is a granuloma?

A structured immune cell cluster surrounding infected macrophages during TB

What are two important MTB surface lipids mentioned in lecture?

PDIM and PGL

What did the Schmalstig paper show using Mycobacterium abscessus?

Phages could enter mammalian cells and reduce intracellular mycobacterial burden

Bacteriophage

Virus that infects bacteria

What are the two major phage life cycle options?

Lytic and lysogenic

Which type of phage is preferred for phage therapy?

Strictly lytic phages

Why does host range matter for phages?

Because phages bind specific receptors, so they only infect certain bacteria

What bacterial defense system stores a memory of past phage infection?

CRISPR-Cas

What is one advantage of phage therapy over antibiotics?

It is more specific and causes less collateral damage to the microbiota

What is one disadvantage of phage therapy?

Its host range can be very narrow

What is arbitrium?

A phage communication system that helps regulate lysis versus lysogeny

What did Aframian 2022 show about prophages and arbitrium?

Lysogens continue to signal and use arbitrium to repress induction when lysogens are abundant

Microbiome

The community of microorganisms and their environment that helps maintain health and affects infection susceptibility

What is colonization resistance?

The ability of the microbiota and host to prevent invading microbes from establishing infection

Name two major ways the microbiota protects against pathogens.

Competition for niches/resources and stimulation of host defenses

What are SCFAs?

Short-chain fatty acids produced by microbial fermentation

Name the three major SCFAs.

Acetate, propionate, and butyrate

How can propionate affect Salmonella?

It can inhibit growth by disrupting intracellular pH homeostasis

How can the microbiota affect mucosal barrier function?

By influencing mucin production, tight junctions, AMPs, and IgA

What common disruption can weaken colonization resistance?

Antibiotics

What happens to the vaginal microbiome during pregnancy according to lecture?

Lactobacillus increases

What did Xerri 2022 show about Bacteroides thetaiotaomicron and Shigella?

Its outer membrane vesicles repressed Shigella virulence and invasion