Lecture 13 - E. coli

How does E. coli cause UTIs?

Usually in the hospital thru urinary catheters or abnormalities, fecal incontinence

How is Lactobacilli a commensal organism in our microbiome?

It inhibits UPEC colonization by creating an acidic environment but can be compromised thru BC or spermicide

How does UPEC bind?

It uses Type 1 and P pili (PAP)

How does Type 1 Pili work

It binds mannose residues on host glycoproteins

How does P pili work?

It binds to globobiose attached to kidney cells

What happens after attachment?

The bacteria can invade bladder “Facet” cells coated in uroplakin proteins

What are the layers of the urothelium and uroplakin plague

Basal, intermediate, and apical layers

What is the basal cell layer?

Attached to a basement layer

What is the apical layer

Large hexagonal cells also known as umbrella cells. The surfaces create a unique asymmetric unit membrane

What is the sequence of UPEC invasion?

It is cyclical in nature and the acute infection can continue

Early stage of UPEC invasion

Average bacteria size is 3um and doubles in size every 30mins

Middle stage of UPEC infection

The bacteria decrease in size to 1um and start doubling every 45 mins

Late stage of UPEC infection

Bacteria return to rod shaped 3um and the filamentous bacteria can escape and invade other cells to continue the cycle

Flagella of UPEC

Provides motility and can change from peritrichous to polar

LPS Toxin of UPEC

Contributes to inflammation

Alpha Hemolysin of UPEC

Member of the RTX pore forming family

CNF-1 of UPEC

Cytotoxic necrotizing factor that kills epithelial cells

Which O antigens are present in the LPS

O1, O4, O6, and O18

UPEC Pathogenicity Islands

Four different main types and have different %G+C content

Which strain of disseminated E. coli causes neonatal meningitis?

E. coli K1

S fimbriae of disseminated E. coli

Binds to cellular fibronectin

OmpA porin of disseminated E. coli

Facilitates invasion of endothelial cells

CNF-1 of disseminated E. coli

Can activate Rho GTPases and deregulate cell function

What is NDM-1?

New Delhi metallo-beta-lactamase

What does NDM-1 do?

An enzyme that can make bacteria resistant to most beta-lactam antibiotics

What is the significance of NDM-1 on carbapenem?

Carbapenem is a beta-lactam used when bacteria are resistant to other antibiotics but NDM-1 can cleave carbapenem

What can NDM-1 cause in healthcare professionals?

Pneumonia and UTIs

What are some risk factors associated with aspiration pneumonia with E. coli

Alcoholism, tube feedings