Session 11: Chronic Diseases and Infections

Question 1

Brief examples of how chronic ilnesses can make one more susceptible to infections.

Answer 1

Can cause change in the structure or function of affected tissues/organs. Changing the interaction between patient and micro-organism.

Changes can be caused by the altered presence of micro-organisms and the consequences of treatment like with antibiotics and steroids.

Question 2

Brief summary of cystic fibrosis.

Answer 2

Autosomal recessive disease with a defect in CFTR gene of exocrine glands. The CFTR gene is supposed to code for cAMP regulated chloride channels but in cystic fibrosis it doesn’t. This leads to reduced Cl- secretion and to more water reabsorbed. Making secretions thicker.

Question 3

Complications of cystic fibrosis.

Answer 3

Colonisation and infection of various organisms in the lungs leading to respiratory infections.

Pancreatitis

Diabetes

Malabsorption (pancreas related)

Thick secretions in intestines cause bowel obstructions in newborns.

Liver cirrhosis

Sinus infections and infertility.

Question 4

Why do patients with CF get infections?

Answer 4

Compromised innate immune system.

The mucus becomes dehydrated and thicker leading to reduced ciliary action and airway remodelling making you much more susceptible to resp. infections.

Question 5

What infections are patients with CF susceptible to?

(Microorganisms)

Answer 5

Haemophilus influenzae

Staphylococcus aureus

Pseudonomas aeruginosa

Burkholderia cepacia

Atypical Mycobacteria

Candida albicans

Aspergillus fumigatus

Question 6

Description of Pseudonomas aeruginosa.

Answer 6

Aerobic, gram-negative bacilli with flagella.

Common in immunocompromised individuals as an opportunistic infection. Due to a break in first line defences of the body to cause infection (innate).

Question 7

Where can Pseudomonas aeruginosa be found?

Answer 7

Soil, coastal areas, plant+animal tissue

Can be found in healthy individuals as well.

Question 8

Mechanism of action + virulence factors of Pseudomonas aeruginosa.

Answer 8

Causes biofilms because the cycle of inflammation in CF damages the local epithelium. This makes a perfect setting for the microorganism.

Hard to eradicate as it is often resistant to antibiotics with multiple virulence factors.

Question 9

Identification of Pseudomonas aeruginosa.

Answer 9

Sputum culture

Question 10

Prevention of resp. infections in CF.

Answer 10

Encourage mucus clearance like chest physiotherapy, nebulisers and bronchodilators.

Steroids to reduce inflammation (can be counterproductive)

Prophylactic antibiotics to prevent colonisation.

Avoid mixing with other CF patients

Good hand hygiene

Maintain good nutrition.

Question 11

Treatment of pseudomonas aeruginosa.

Answer 11

As they tend to rapidly develop resistance you often need to use a combination of antibiotics.

Ciprofloxacin

Tazocin

Gentamycin

Ceftazidime

Question 12

Why do patients with diabetes get infections?

Answer 12

Hyperglycaemia giving more nutrients to bacteria.

Humoral immunity

Neutrophil and lymphocyte functions impairment.

Poor tissue perfusion

Diminished sensation due to diabetic neuropathy leading to unnoticed skin ulcers and cuts (innate breach)

Question 13

Infections of susceptibility in patients with diabetes.

Answer 13

Cellulitis

UTIs

Malignant otitis externa

Resp. infections

Question 14

Why is cellulitis common in diabetes?

(Causative organisms)

Answer 14

Hyperglycaemia

Impaired sensation (more ulcers leading to invasion of skin organisms)

Reduced perfusion (atherosclerosis)

Staph. aureus
Group A beta-haemolytic streptococcus
Polymicrobial

Question 15

Diabetic foot ulcer presents in A&E.

Investigations:

Answer 15

Swab site for culture

Blood markers like FBC and CRP

Foot x-rays to check for osteomyelitis

Renal function by checking U&Es

Check glycaemic control by BM and HbA1c

Question 16

Treatment of diabetic-related cellulitis.

Answer 16

Treat infection

Good glycaemic control

Reduce other cardiovascular risk factors

Make them check their feet regularly

Good foot care

Question 17

Why are diabetics more susceptible to UTIs?

Answer 17

Diabetic neuropathy leads urine retention -> stasis of urine leading to a breeding ground for bacteria.

Glycosuria leads to increased bacterial infections.

Question 18

Causative organisms of UTIs in patients with diabetes.

Answer 18

Enterobacteriaceae like E. coli

Pseuodomonas aeruginosa

Question 19

Investigation of UTI in diabetic patient.

Answer 19

Urinalysis like nitris and leucocytes along with glycosuria.

If it is considered more severe or ascending infection (more common in men) do a sepsis screen and FBC, CRP and U&Es.

Question 20

Management of UTIs in diabetes.

Answer 20

Treat infections (Trimethoprim or nitrofurantoin)

Good glycaemic control

Question 21

Brief summary of malignant otitis externa.

(What is it, spread, symptoms)

(Causative organism)

Answer 21

External ear infection starting in external auditory canal.

Spread to adjacent soft tissue, cartilage and bone.

Severe ear pain and otorrhea (ear discharge)

Pseudomonas aeruginosa

Question 22

Why do diabetics get resp. infections?

Answer 22

Hyperglycaemia impairing neutrophil function.

Altered perfusion causing further inflammatory processes.

Question 23

Causative organisms of resp. infections in diabetics.

Answer 23

Streptococcus pneumoniae

H. influenzae

Mycoplasma pneuomoniae/Chlamydia pneuomoniae

Staphylococcus aureus

In the case of influenza vaccines are offered to DM patients.

Question 24

Brief summary of COPD.

Answer 24

Chronic obstructive pulmonary disease.

Chronic inflammatory response to inhaled irritants, primarily mediated by neutrophils and macrophages associated with smoking.

Question 25

Why do patients with COPD get infections?

Answer 25

Local overreactivity leading to inflammation and damage to airways.

There is a breakdown of lung tissue (emphysema) and small airways disease (obstructive bronchitis). This leads to airway remodelling and damage to the cilia.

There is an increased mucus production and damage to mucociliary escalator.

Question 26

What infections are patients with COPD more susceptible to?

Answer 26

Pneumonia

H. influenzae

Pseudomonas aeruginosa

(More rare):

Streptococcus pneumoniae

Moraxella catarrhalis

E. coli