Chronic Infections

Question 0

What are the typical bacteria and viruses found in COPD?

Answer 0

BACTERIA:

• Streptococcus pneumoniae
• Haemophilus influenzae
• Moraxella cattarhalis
• Pseudomonas aeruginosa
• Escherichia coli

VIRUSES:

• RSV
• rhinovirus
• (para)influenza
• human metapneumovirus
• coronavirus
• adenovirus
• influenza A virus

Question 1

What is the pattern of lung colonisation in cystic fibrosis patients?

Answer 1

1-2yrs: Haemophilus influenzae

2-3yrs: Staphylococcus aureus, Pseudomonas aeruginosa (hallmark of CF), Burkholderia cepacia

Teens-20’s: atypical Mycobacterium (i.e. not TB), Candida albicans, Aspergillus fumigatus

note: Pseudomonas aeruginosa: biofilm formation, releases toxins, mucoid phenotype (resistant to innate & adaptive immune system), antibiotic resistant

Question 2

Why are diabetics prone to infection?

Answer 2

• neuropathy —> neurogenic bladder (defective bladder emptying) & unnoticed skin wounds
• micro/macrovascular disease —> poor tissue perfusion (poor healing & invasion of necrotic tissue by microbes)
• hyperglycaemia & acidaemia (impaired antibody production & impaired function of neutrophils & lymphocytes)

Question 3

What is malignant/necrotising otitis externa?

Answer 3

Pseudomonas aeruginosa supercolonisation (e.g. due to antibiotic treatment) of external auditory canal which spreads to adjacent soft tissue, cartilage, and bone

—> severe ear pain & otorrhoea (pus leakage)

Question 4

What is rhinocerebral mucormycosis?

Answer 4

Mould infection of nose and paranasal sinuses (e.g. Aspergillus) which spreads to adjacent tissues by invading blood vessels

—> soft tissue necrosis & bone erosion

Question 5

What are the typical bacteria which when found in the urine indicate neurogenic bladder?

Answer 5

Coliforms

Pseudomonas aeruginosa

Question 6

What are some examples of soft tissue infections?

Answer 6

Cellulitis - Staphylococcus aureus, Group A beta-haemolytic Streptococus

Folliculitis - Staphylococcus aureus

Diabetic foot ulcers/necrotising fasciitis - Staphylococcus aureus, beta- haemolytic Streptococci, Enterobacteriaceae, various anaerobes

Question 7

Why are respiratory tract infections (possibly) more common in Down’s syndrome?

Answer 7

True immunodeficiency?

Heart defects cause more serious presentation?

Cross-infection in institutionalisation (reduced to normal levels now due to community care)?

Altered structure of mouth/airways?

Altered mucus secretions?