Urinary Tract Pathogens

M.7R, W.2, L.1

List three lower UT infections

• Kidney - Pyelonephritis

• Bladder - Cystitis

• Urethra - Urethritis

List the main UTI pathogens (7)

• E.coli

• Klebsiella

• Enterococcus

• Proteus

• Pseudomonas

• Staphylococcus

• Corynebacterium

Which UTI pathogens come from the gut?

• E.coli

• Klebsiella

• Enterococcus

Explain why sex anatomical differences impact UTI risk.

• Female - shorter distances between anus and urethra makes infection from gut commensals easier

• Male - longer urethra makes bladder harder to reach for pathogens

What is a gram-negative bacteria

Single-celled microorganisms that have:

• double membrane: inner cell membrane and outer lipid membrane

• thin peptidoglycan layer (sits between the two membranes)

• endotoxins: outer membrane contains lipopolysaccharides (toxic molecules that trigger severe immune response)

Describe Uropathogenic E.coli (UPEC) (pos or neg, and characteristics)

Main UTI cause

• gram-negative

• have UT-specific fimbriae

• express cytotoxic factors

  • (hemolysin - breaks down RBCs)

• iron uptake systems (to help grow)

• no urease activity

• intracellular infections

What are fimbriae and list their function

• hair-like structures

• used to stick to surfaces like the epithelium in the UT

What does UPEC gain from being cytotoxic?

• The environment is not rich in nutrients, since UPEC can’t digest urea

• cytotoxic factors break cells open of the epithelium in order to get nutrients out

Describe Klebsiella spp. (pos or neg, shape, characteristics, motile?, resistant?)

• Gram-negative

• rod-shaped

• fimbriae

• non-motile

• capsule (mainly in UT)

• intrinsically resistant to B-lactam antibiotics

Describe Enterococcus spp. (pos or neg, shape, motile?, characteristics, associated to?)

• Gram-positive

• round-shaped (splits in middle)

• non-motile

• strong biofilm formers

• often associated to catheters

  • CAUTI (catheter associated UTI)

What is a gram-positive bacteria?

Microorganism that has:

• thick peptidoglycan cell wall layer

• No outer membrane

• Techoic acids (in cell wall; helps transport nutrients)

Describe Proteus spp. (pos or neg, pattern on petri dish, shape, characteristics)

• Gram-negative

• concentric rings on petri dish

• rod-shaped

• flagella

• have signal-receptor system

  • used to recognize themselves

What happens when the signal-receptor system doesn’t work?

they start killing each other (because they don’t recognize themselves)

Describe the key behavior pattern of Proteus cells

short cells → differentiation and cell division → lag → Swarmer cells → migration → halt motility and consolidation through cell division → short cells

Describe the most important characteristic of Proteus spp.

• Proteus releases urease

  • urease breaks urea in the urine into CO2 & ammonia

    • ammonia reacts with H2O →

      raises pH to create alkaline environment

      • ions solidify into crystals: struvite & apatite

List the main factors of Proteus UTI

• Swarming (ascending infections)

• Fimbriae

• Toxins (hemolysin)

• Urease

Describe Pseudomonas spp. (pos or neg, shape, motility, petri dish appearance, resistance)

• gram-negative

• rod-shaped

• motile

• makes pigment to scavenge iron (green petri dish)

• intrinsically resistant to several antibiotics

Describe Staphylococcus spp. (pos or neg, shape, motility, produce what?)

• Gram-positive

• round-shaped

• non-motile

• strong biofilm formers

• produce urease (stones formation)

• produce coagulase (clots formation)

Describe Corynebacterium spp. (pos or neg, shape, motility, produce what, growth rate)

• Gram-positive

• rod-shaped

• non motile

• urease producers (can lead to stones)

• biofilm forming

• fastidious, slow growers

  • makes them multi-drug resistant

List diagnostics for a UTI

• quick: urine strip test

• laboratory diagnostics (chromogenic agar)