Week 3 : Patho of Hospital Acquired Infections (Dr. Smith)

Question 1

Pathogen [Typical & Opportunistic] : Definition

Answer 1

Pathogen: causative organism
• Typical—organism that is the most common cause for a given infection
• Opportunistic—organisms that are typically only seen in patients who are
immunocompromised

Question 2

Virulence: definition

Answer 2

a measure of pathogenicity

Question 3

Resistance: definition

Answer 3

a measure of tolerance to available antibiotics

Question 4

How does antibiotic resistance spread?

Answer 4

• Resistance from human use of antibiotics

- Resistance from agricultural use of antibiotics

Question 5

What is the biggest risk for hospital - acquired urinary tract infections

Answer 5

catheters

Question 6

Big risk for hospital acquired pneumonia

Answer 6

Occurs in 10-20% of patients who are on a ventilator >48h

• Problematic because typically is a drug- resistant bacterial infection

Question 7

Hospital acquired gram negative infections:

-Virulence factors

Answer 7

• Virulence factors:
  (a) Adherence
  (b) toxin production

Question 8

Non-specific host defenses: GN infections

Answer 8

Physical Defenses
• Skin and mucous membranes 
•Desquamation: epithelial cell turnover
• Acidity
• Skin conditions not ideal

Innate Immunity
• Physical Elimination
• Cellular Elimination: 
By complement—anti-microbial proteins
‒By phagocytic immune cells—macrophages, neutrophils 
• Cytokines
• Fever
• Iron sequestration in the liver

Question 9

Which is the most numerous white blood cell at site of infection?

Answer 9

Neutrophils

Question 10

Specific host defenses: key cells, key proteins

Answer 10

Key cells:
• Macrophages
• B-lymphocytes
• T-lymphocytes

Key proteins: Immunoglobulin (IgG, IgM)

Question 11

What do plasma b cells do?

Answer 11

produce circulating antibodies

Question 12

Most common pathogens for UTI:

(a) in general
(b) Catheter- associated Urinary Tract infections

Answer 12

(a) in general:
E.coli

(b) Catheter- associated Urinary Tract infections:
E.coli, Pseudomonas aeuginosa

Question 13

Cystitis: Host Preparation

Answer 13

• Secretion of antimicrobial peptides

- Spontaneous shedding of superficial cell layer

Question 14

Cystitis: Host Response

Answer 14

Neutrophils
• First immune cells to be recruited to bladder

Adaptive Immune Response
• Typically limited for UTIs
• Meaning no “learned” immunity for the most part

Question 15

Cystitis: Cellular/ Molecular Pathogenesis

Answer 15

Colonization

• Presence of microorganism with growth/replication, but without interaction with organism

Question 16

E.coli: Virulence factors

Answer 16

-Siderophores
• Molecules secreted by bacteria to find iron and return it to the bacteria

-Type 1 Pili/Flagella
• Aid in bacterial mobility

-Alpha-hemolysin
• Forms pores in cells to promote bacterial internalization

Cytotoxic Necrotizing Factor 1 (CNF1)
• Promote bacterial internalization into cells

Question 17

Extended Spectrum β-lactamase (ESBL); What is it?

Answer 17

• Confer resistance to cephalosporins

* Reduce possible treatment options available

Question 18

Hospital-acquired Pneumonia: Most common pathogens

Answer 18

1. Staphylococcus aureus

2. Pseudomonas aeruginosa

Question 19

Ventilator - associated Pneumonia: most common pathogens

Answer 19

1. S. auereus

2. P. aeruginosa

Question 20

Problem with co-infection of bacterias

Answer 20

Harder to treat

Question 21

Which bacteria have the highest resistance rates in ventilator associated pneumonia?

Answer 21

Acinetobacter baumannii &
Pseudomonas aeruginosa
exhibit the HIGHEST rates of antibiotic resistance