microimm bacteria cram

Yersinis pestis

gram negative rod bac that caused plague. major virulence factors:

• LPS: allows survival in vector + no O antigen, decreased detection from immune systemGram-negative

• Plasminogen activator: allows tissue invasion

• type 3 secretion: prevents phagocytosis

Intracellular, hides in macrophages and infects other ones → bacteremia

Transmission: rats to fleas to humans, then aerosols

Klebsiella pneumoniaie

gram negative bac that causes pneumonia. major virulence factors:

• LPS

• Resistance to beta lactamase, carbapanemase

• biofilm
  

coloniizes in respiratory tract → bacteremia

Transmission:

aerosols

Clostridioides difficile

gram positive bac that causes pseudomembrane colitis. major virulence factors:

• Toxins A&B

• Endospores that resist stress

Found in gut biome, disruption causes it to release exotoxins and damage intestinal epithelial cells.

Transmission: nosocomial

Reservoir: GI tract

Mycobacteria tuberculosis

acid fast bacteria that causes TB. major virulence factors:

• thick mycolic acid layer

• type 7 secretion system

• resistance to oxidative stress

active TB cells are eaten by macrophages but survive. they infect other macrophages and mount an inflammatory response

Transmission: aerosols if active TB

Mycobacteria leprae

gram positive acid fast bacteria that causes leprosy. virulence factors include:

• mycolic acid layer

bacteria infect macrophages and they are reprogrammed to damage nerve cells (schwann cells)

Transmission: prolonged close contact and aerosols

Mycobacterium bovis

acid fast bac that causes a form of TB. major virulence factors:

• mycolic acid rich cell wall

• type 7 secretion system

• immune evasion

Entry via oral route (from ingesting unpasteurized dairy). Bacteria are taken up by macrophages and phagocytes where they survive and replicate slowly. If immunity is strong, the bacteria will be contained in granulomas, if its weak bacteria will spread to the bloodstream. Also they’ll activate T-cells and t-cell mediated immunity will occur → inflammatory response.

reservoir: cows

Neisseria meningitidis

gram negative bac that causes bacterial meningitis. virulence factors:

• antigenic variation (various serotypes)

• Capsule → allows protection from complement system

• LPS → septic shock

colonizes in nasopharyngeal cavity and spreads to blood and replicates. Crosses over BBB, recruits WBC and mounts a strong inflammatory response

transmission: Aerosols

Streptococcus pneumoniaie

gram positive bacteria that causes bacterial meningitis, pneumonia, etc. major virulence factors:

• capsule

• >90 serotypes

same pathogenic mech as N.meningitidis

transmission: during labour

Haemophilus influenzae Type B

gram negative bac that causes meningitis. major virulence factors:

• capsule

same pathogenic mechanism as N. meningiditis

transmission: during birth

Listeria monocytogenes

gram positive bac that causes meningitis. major virulence factors:

• no capsule

• actA expression, allows motility

colonize in intestinal epithelial cells and moves around and infects other cells using actin. infects bloodstream then meninges

transmission: food borne, during birth

Borrelia burgdorferi

gram negative bac that causes lyme disease. major virulence factors:

• Antigenic variation

• Axial filaments

• Lipoproteins → adhesins

bacteria move from salivary glands of nymphs and colonize in the skin first (bullseye rash) and then bloodstream (bacteremia)

reservoir: mice

transmission: vector transmission

Treponema pallidum

gram negative spirochete that causes syphilis. Major virulence factors:

• NO LPS

• Endoflagella

• Antigenic variation (TprK)

• Cytolysin

Colonizes in micro abrasions then replicates in bloodstream → inflammation

transmission: vertical or sexual transmission

Chlamydia trachomatis

gram negative bac that causes chlamydia. Major virulence factors:

• elementary body: infectious

• Reticulate body: replicates

• Type 3 secretion

• Heatshock protein: triggers inflammation

transmission: vertical or sexual

Neisseria gonorrhoeae

gram negative bac that causes gonorrhea. major virulence factors:

• type 4 pili

• LOS → inflammation

• Opacity protein → invasion

colonizes in urogenital epithelial cells and LOS-mediated inflammation occurs

Streptococcus pyogenes

gram positive spherical bac that causes strep throat, impetigo, scarlet fever (non invasive) and meningitis, necrotizing fasciitis, toxic shock syndrome (invasive). Major virulence factors:

• Capsule: non immunogenic

• M protein: prevents complement + phagocytosis

• Exotoxins: Superantigens → inflammation

colonization in the throat or skin and then evades phagocytosis using M protein and capsule. Superantigens will induce strong inflammation response, and then widespread dissemination happens by destroying host machinery.