Session 11: Chronic Diseases and Infections Flashcards
Brief examples of how chronic ilnesses can make one more susceptible to infections.
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.
Brief summary of cystic fibrosis.
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.
Complications of cystic fibrosis.
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.
Why do patients with CF get infections?
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.
What infections are patients with CF susceptible to?
(Microorganisms)
Haemophilus influenzae
Staphylococcus aureus
Pseudonomas aeruginosa
Burkholderia cepacia
Atypical Mycobacteria
Candida albicans
Aspergillus fumigatus
Description of Pseudonomas aeruginosa.
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).
Where can Pseudomonas aeruginosa be found?
Soil, coastal areas, plant+animal tissue
Can be found in healthy individuals as well.
Mechanism of action + virulence factors of Pseudomonas aeruginosa.
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.
Identification of Pseudomonas aeruginosa.
Sputum culture
Prevention of resp. infections in CF.
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.
Treatment of pseudomonas aeruginosa.
As they tend to rapidly develop resistance you often need to use a combination of antibiotics.
Ciprofloxacin
Tazocin
Gentamycin
Ceftazidime
Why do patients with diabetes get infections?
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)
Infections of susceptibility in patients with diabetes.
Cellulitis
UTIs
Malignant otitis externa
Resp. infections
Why is cellulitis common in diabetes?
(Causative organisms)
Hyperglycaemia
Impaired sensation (more ulcers leading to invasion of skin organisms)
Reduced perfusion (atherosclerosis)
Staph. aureus
Group A beta-haemolytic streptococcus
Polymicrobial
Diabetic foot ulcer presents in A&E.
Investigations:
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
Treatment of diabetic-related cellulitis.
Treat infection
Good glycaemic control
Reduce other cardiovascular risk factors
Make them check their feet regularly
Good foot care
Why are diabetics more susceptible to UTIs?
Diabetic neuropathy leads urine retention -> stasis of urine leading to a breeding ground for bacteria.
Glycosuria leads to increased bacterial infections.
Causative organisms of UTIs in patients with diabetes.
Enterobacteriaceae like E. coli
Pseuodomonas aeruginosa
Investigation of UTI in diabetic patient.
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.
Management of UTIs in diabetes.
Treat infections (Trimethoprim or nitrofurantoin)
Good glycaemic control
Brief summary of malignant otitis externa.
(What is it, spread, symptoms)
(Causative organism)
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
Why do diabetics get resp. infections?
Hyperglycaemia impairing neutrophil function.
Altered perfusion causing further inflammatory processes.
Causative organisms of resp. infections in diabetics.
Streptococcus pneumoniae
H. influenzae
Mycoplasma pneuomoniae/Chlamydia pneuomoniae
Staphylococcus aureus
In the case of influenza vaccines are offered to DM patients.
Brief summary of COPD.
Chronic obstructive pulmonary disease.
Chronic inflammatory response to inhaled irritants, primarily mediated by neutrophils and macrophages associated with smoking.
Why do patients with COPD get infections?
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.
What infections are patients with COPD more susceptible to?
Pneumonia
H. influenzae
Pseudomonas aeruginosa
(More rare):
Streptococcus pneumoniae
Moraxella catarrhalis
E. coli
