Session 11 Flashcards
(31 cards)
How can chronic diseases predispose patients to specific and characteristic infections?
◦ Can cause a change in the structure or function of affected tissues/organs ◦ May have the potential for changing the interaction between the patient and micro-organisms
◦ Changes can be caused by the altered presence of micro-organisms
and the consequences of treatment
e.g. with antibiotics and steroids
What is cystic fibrosis?
Autosomal recessive condition.
Defect in cystic fibrosis transmembrane
conductance regulator (CFTR) gene in exocrine glands
◦ Codes for cAMP regulated chloride channel
Reduced secretion of Cl-
◦ More water reabsorbed
What are the complications of Cystic Fibrosis?
Complications include:
◦ Lungs - colonisation and infection with various organisms
◦ Pancreas - inflammation of the pancreas (pancreatitis), Diabetes, malabsorption
◦ Intestines - thick secretions can cause bowel obstruction in newborns (“meconium ileus”)
◦ Damage to liver - cirrhosis
◦ Sinus infections
◦ Infertility
Why do patients with cystic fibrosis get infections?
Compromised innate immune system:
Mucus becomes dehydrated and thick
Can impair clearance of organisms from the body
◦ Reduced ciliary action
◦ Airway remodelling - Body tries to fix damage but as a result less functional.
What infections are patients with Cystic Fibrosis susceptible to?
H influenzae
Staph aureus
Pseudomonas aeruginosa, Burkholderia cepacia
Atypical Mycobacteria, Candida albicans, Aspergillus fumigatus
Describe the basic properties of Pseudomonas aeruginosa?
Gram negative bacilli
◦ Flagella
◦ Aerobic Typically affects immunocompromised individuals
◦ Opportunistic infection
◦ Must be a break in first line defences of the body to cause infection
◦ Common cause of hospital acquired infections
Where can Pseudomonas aeruginosa be found?
Can be found in the environment
◦ Soil, coastal areas, plant/animal tissue
◦ Can also be found in healthy individuals
How does Pseudomonas aeruginosa cause damage?
Causes biofilms
◦ Cycle of inflammation in CF damages local epithelium
◦ Therefore perfect setting for pseudomonas to cause biofilms
Very hard to eradicate
◦ Often resistant to antibiotics
◦ Multiple virulence factors
How do we identify Pseudomonas aeruginosa?
Sputum culture useful to identify organism and specific sensitivities
What steps can be taken to prevent respiratory infections developing in cystic fibrosis patients?
Encourage mucus clearance
◦ Chest physiotherapy
◦ Nebulisers
◦ Bronchodilators
Sometimes steroids are used to reduce inflammation
Prevent colonisation using prophylactic antibiotic
Avoid mixing with other cystic fibrosis patients
Good hand hygiene
Maintain good nutrition
How do we treat Pseudomonas aeruginosa
infection?
Pseudomonas tends to rapidly develop resistance Often need a combination of multiple antibiotics Examples: ◦ Ciprofloxacin ◦ Tazocin ◦ Gentamycin (or other aminoglycoside) ◦ Ceftazidime (cephalosporin)
Why do patients with diabetes get infections?
Hyperglycaemia and academia impair:
◦ Humoral immunity:
◦ Neutrophil and lymphocyte functions Diabetic microvascular and macrovascular disease result in poor tissue perfusion and increased risk of infection
Diabetic neuropathy causes diminished sensation
◦ unnoticed skin ulcers or cuts; breach of innate immunity
What infections are patients with diabetes susceptible to?
Cellulitis
Urinary Tract Infections (UTIs)
Malignant otitis externa
Respiratory infections
Why is Cellulitis common in patients with diabetes mellitus?
Soft tissue infections are commonly found in diabetic patients due to:
◦ Hyperglycaemia
◦ Impaired sensation
◦ Reduced perfusion (atherosclerosis)
What are the causative organisms of cellulitis and other skin conditions with diabetes mellitus?
Causative organisms include:
◦ Staph aureus (folliculitis, cellulitis)
◦ Group A β-haemolytic Streptococcus (cellulitis)
◦ Polymicrobial (Diabetic foot ulcers)
What investigation would do you do if someone walks in with a diabetic foot ulcer?
Investigations: Identify the infection
◦ Swab the site for culture What is the severity of the infection?
◦ Blood markers (FBC, CRP)
◦ Foot X-ray (? osteomyelitis)
◦ Renal function (U&Es) What is their glycaemic control like?
◦ BM/ HbA1c
How do you treat diabetic-related cellulitis?
- Treat the infection
- Good glycaemic control 2. Reduce other cardiovascular risk factors
- Check feet regularly
- Good foot care
Why can UTIs also be common in diabetic patients?
◦ Diabetic neuropathy leads to defects in bladder emptying
◦ Reduced emptying = stasis
◦ Glycosuria (glucose in urine) - Increased bacterial infections
What are the common causative organisms for UTI’s in diabetic patients?
Causative organisms include:
◦ Enterobacteriaceae (e.g. E coli)
◦ Pseudomonas aeruginosa
What investigations would you do for a diabetic patient with a UTI?
Investigations: Urinalysis ◦ Nitrites & leucocytes ◦ Glycosuria If considering more severe or ascending infection… ◦ Sepsis screen ◦ FBC, CRP, U&Es
How would you manage UTI’s in diabetic patients?
Treat Infection
Good glycaemic control
What is Malignant otitis externa?
External ear infection
Starts in the external auditory canal
Spreads to adjacent soft tissue, cartilage, and bone
Causative organism is Pseudomonas Aeruginosa.
How do patients with Malignant otitis externa present clinically?
Patients typically present with severe ear pain and otorrhoea (drainage of liquid from the ear)
What is the causative organism for Malignant otitis externa?
Pseudomonas aeruginosa
