Denise - Pseudomonas Flashcards by Aífe Hayden

What are the reservoirs for Pseudomonas

Free-living bacterium
Found in the environment (soil, water, sewage, moist surfaces, hot tubs)
Found on plants and animals

How well did you know this?

Not at all

Perfectly

When can pseudomonas cause problems
(3)

Plant pathogens
Food spoilage organisms
Bioremediation - present in water

How well did you know this?

Not at all

Perfectly

How would pseudomonas be transmissed
(4)

Direct contact with water - ingestion or bathing

Inhalation of aerosols

Medical Devices rinsed with contaminated water

Indirect contact from contaminated surfaces via the hands of health care workers

How well did you know this?

Not at all

Perfectly

How common is pseudomonas in the lab?
(4)

15% of clinical bacterial isolates in the lab

Very common hospital acquired infection

Often multi drug resistance

An ESKAPE Pathogen

How well did you know this?

Not at all

Perfectly

What percentage of HCAI are pseudomonas species?

4% of HCAI

How well did you know this?

Not at all

Perfectly

Comment on P. aeruginosa and immunocompromised patients
(4)

Pseudomonas increasingly recognised as an opportunistic pathogen

Pseudomonas is common in present in moist environments in hospitals especially in respiratory therapy equipment, Dialysis tubing catheters

It is pathogenic when introduced into areas devoid of normal defences or the immunocompromised

Dysfunctional Immune System

How well did you know this?

Not at all

Perfectly

Who is at risk of P. aeruginosa infections due to dysfunctional immune system?
(6)

Neonates
Cystic fibrosis
AIDA
Neutropenia
Complement Deficiency
Hypogammaglobulinemia

How well did you know this?

Not at all

Perfectly

Who is at risk of Pseudomonas infections due to disruption of physical barriers?
(5)

Burn injuries

Intravenous IV lines

Urinary catheters

Dialysis catheters

Endotracheal tubes

How well did you know this?

Not at all

Perfectly

Pseudomonas infects what areas of the body

Respiratory tract
Ear
GI tract
Urinary tract
Eye
Bones and joints

How well did you know this?

Not at all

Perfectly

What infections does Pseudomonas cause in the respiratory tract?

Pneumonia
Cystic fibrosis

How well did you know this?

Not at all

Perfectly

What infections does Pseudomonas cause in the ear

Otitis externa
Otitis media

How well did you know this?

Not at all

Perfectly

What infections does Pseudomonas cause in the eye

Bacterial keratitis

How well did you know this?

Not at all

Perfectly

What infections does Pseudomonas cause in the Bones and joints

Osteomyelitis

How well did you know this?

Not at all

Perfectly

What infections does Pseudomonas cause in the GIT?

Diarrhoea, enteritis, enterocolitis

How well did you know this?

Not at all

Perfectly

What are the five types of systemic infections that Pseudomonas can cause

Blood stream infections
Secondary pneumonia, bone and joint infections
Endocarditis
CNS
Skin and soft Tissue infections

How well did you know this?

Not at all

Perfectly

Comment on the invasiveness of Pseudomonas
(2)

Invasive P.aeruginosa infections are on the increase

MDR strains have fluctuated between 4-9% since 2014

How well did you know this?

Not at all

Perfectly

What is the first step in P. aeruginosa infection

Colonisation

How well did you know this?

Not at all

Perfectly

Comment on the colonisation of P. aeruginosa

Break in first line defence
Cell associated virulence factors

How well did you know this?

Not at all

Perfectly

Comment on the P. aeruginosa in an acute infection
(4)

Virulence factors increased

Protease toxins

Invasion

Tissue damage

How well did you know this?

Not at all

Perfectly

Comment on P. aeruginosa in chronic infections
(3)

Persistent pulmonary infection in Cystic Fibrosis

Formation of biofilm

Virulence factors lower

How well did you know this?

Not at all

Perfectly

List the cell associated factors that promote colonisation in P. aeruginosa infections
(2)

Pili
Capsule

How well did you know this?

Not at all

Perfectly

What virulence factors cause systemic infections in P. aeruginosa?
(2)

Exotoxin A
Endotoxin

How well did you know this?

Not at all

Perfectly

What extracellular factors degrade tissue and promote invasion?
(4)

Proteases
Elastases
Phospholipase C
Exotoxin A

How well did you know this?

Not at all

Perfectly

Comment on the LPS of P. aeruginosa

There is some structural variability of LPS
It differs between mucoid to nonmucoid transition

How well did you know this?

Not at all

Perfectly

What are the two secreted components of P. aeruginosa?

Pyocyanin Alginate slime

What does pyocyanin do? (2)

Interferes with the antioxidant defences in the lung Facilitates oxidative damage to the lung epithelium

What does alginate slime do? (2)

Matrix of biofilm formation Impairs cillary function

List the exotoxins and exoenzymes of P. aeruginosa (4)

Leukocidin Elastase Alkaline Protease Phospholipase C

What does elastase do? (3)

Destruction of elastin Cleaves IgG, IgA, Complement Degrades surfactant proteins A and D

What does alkaline protease do?

Lyses fibrin

What does phospholipase C do?

A class of membrane-associated enzymes that cleave phospholipids

What does leukocidin do? (2)

A type of cytotoxin or exotoxin A pore-forming toxin that kills or destroys white blood cells by creating holes in their membranes

Write about exotoxin A

ADP ribosylation Inactivation of elongation factor 2 Inhibits protein synthesis Regulated by environmental iron availability

What does exotoxin S do?

It impairs the function of phagocytic cells

What type of secretion system does Pseudomonas aeruginosa employ

The type III secretion system

What four effector proteins make up the type III secretion system of Pseudomonas?

ExoS ExoT ExoU ExoY

What does ExoU do?

Rapid destruction of host cell membranes Is greater in P. aeruginosa isolated in hospital ICUs and burn units

What does ExoS do

Relevant in patients with CF

Which protein effectors of the type 3 secretion system are mutually exclusive

ExoU and ExoS

What does Pseudomonas produce in chronic infections?

Bacterial biofilms

What biofilm is produced by Pseudomonas

Exopolysaccharide alginate Produced in vitro and in vivo

What is the function of biofilm (5)

Its a survival mechanism for bacteria - it's a form of protection Protects against: - host immune cells - host antibodies - disinfectant - antibodies

Describe sessile vs planktonic (2)

Sessile bacteria grow more slowly and have restricted mobility Planktonic forms in culture media and have unnatural access to nutrients, they multiply rapidly and are often highly motile

Comment on P. aeruginosa and cystic fibrosis

Infection with P. aeruginosa and development of chronic infection is directly related to the loss of lung fucntion in cystic fibrosis

Comment on biofilms in the health care setting (3)

Biofilms form on instruments and implants Equipment (catheters, prosthetic heart valves, prosthetic joints, shunts) Healthcare setting (water systems and air conditioning units)

How is Pseudomonas infections treated? (3)

There is increased resistance during therapy Pseudomonas may acquire resistance during therapy Dual therapy is recommended to avoid resistance that develops rapidly when single antimicrobials are used

Comment on the dual therapy approach to treating Pseudomonas and give two examples of treatment (3)

Two agents from different classes should be used Beta-lactams such as cephalosporin and an aminoglycoside such as tobramycin Carbapenems such as meropenem with a fluroquinolone such as ciprofloxacin

What mechanisms of antimicrobial resistance does P. aeruginosa have? (5)

Permeability barrier Biofilm formation Resistance plasmids Efflux pumps Resistant to disinfectants

Comment on the permeability barrier of the P. aeruginosa

P. aeruginosa is naturally resistant to many antibiotics due to the permeability barrier gram-negative outer membrane

What is the point of biofilm formation

This makes the cells impervious to therapeutic concentrations antibiotics

What is the main method of antimicrobial resistance in P. aeruginosa?

Porins -> pump out the antibiotic

What specimens can be put up for Pseudomonas

Urine Sputum Blood Pus

Psueomonas is usually put up on what media (5)

Blood agar Chocolate agar Moderately selective media - MacConkey media Selective agar - Cetramide agar Incubate aerobically at 37 degrees Celsius for 24-48 hours

How does Pseudomonas look on blood agar (2)

Metallic sheen Sweet odour

How does Pseudomonas look on MacConkey agar?

Non lactose Fermenter (yellow colonies)

How does Pseudomonas look on cetrimide agar?

Enhanced pigment of pseudomonas aeruginosa => bright green colour produced

How does cetrimide agar work

It enhances the production of Pseudomonas pigments such as pyocyanin and pyoverdine which show a characteristic blue-green and yellow-green colour

How can you classify Pseudomonas aeruginosa based on colonial morphology

Non-mucoid to mucoid transition

What are the results of P. aeruginosa basic characteristic tests (3)

GNBs Oxidase positive Weak catalase positive + distinctive morphology e.g. metallic sheen and mucoid colonies

How would you identify Pseudomonas in the lab (4)

Growth on selective media Growth at 42 degrees Celsius Failure to grow at 4 degrees Celsius Biochemical Identification

Can the Maldi/Vitek be used to identify Pseudomonas?

No as there are issues with the Maldi/Vitek especially for the mucoid strains