Microbiology Flashcards
(35 cards)
Some common causes of a sore throat?
Common cold
Influenza
Streptococcal infection
In a person aged 15-25 with sore throat persisting >2 weeks, what should you suspect?
Infective mononucleosis
Why do the majority of sore throats not need antibiotics?
Over 2/3 of sore throats are viral
What is the most common cause of bacterial sore throat?
Treatment?
Streptococcus pyogenes
aka Group A streptococcus
aka Group A beta haemolytic strep
Penicillin
How does Strep pyogenes show on gram stain + haemolysis?
What do you need to keep in mind with this organism?
Gram positive cocci in chains
Complete - beta haemolysis
Extra contact precautions need to be taken into account
Give two late complications of streptococcal sore throat
Rheumatic fever - 3 weeks after sore throat - Fever, arthritis pancarditis Glomerulonephritis - 1-3 weeks after sore throat - Haematuria, albuminuria, oedema
Severe sore throat with a grey white membrane across the pharynx = ?
Which organism and what does it produce?
Diphtheria
Corynebacterium diphtheriae
Produces a potent endotoxin which is cardiotoxic and neurotoxic
What type of vaccine is that for diphtheria?
Toxoid
What is the treatment for diphtheria?
Antitoxin
Penicillin/erythromycin
White patches on red, raw mucous membranes in throat/mouth = ?
Organism?
Cause?
Treatment?
Candida/thrush
Candida albicans
Cause - endogenous
Nystatin
What is acute otitis media? How does it present? What should you remember about the microbiology? Diagnosis? Treatment?
An upper respiratory infection involving the middle ear by extension of infection up the eustachian tube.
Ear ache
Usually viral with secondary bacterial infection
Swab of pus if eardrum perforates – otherwise samples can’t be obtained
80% resolve in 4 days without antibiotics
First line – amoxicillin
Second line – erythromycin
What is acute sinusitis?
What might indicate secondary infection?
Treatment?
Mild discomfort over frontal or maxillary sinuses due to congestion often seen in patients with upper respiratory viral infections.
However, severe pain and tenderness with purulent nasal discharge indicates secondary bacterial infection.
Av. length illness 2.5 weeks. Reserve antibiotics for severe/deteriorating cases of >10 days duration.
1ST LINE penicillin V
2ND LINE doxycycline – NOT IN CHILDREN!!!
What is otitis externa?
Inflammation of the outer ear canal
- Redness and swelling of the skin of the ear canal
- It may be itchy (especially in the early stages)
- Can become sore and painful
- There may be a discharge, or increased amounts of ear wax
- If the canal becomes blocked by swelling or secretions, hearing can be affected
What is it?
Otitis externa
Management of otitis externa?
Management
- Topical aural toilet
- Swab to microbiology and prescription of antimicrobial reserved for unresponsive or severe cases
Treat depending on culture results
- Topical clotrimazole (trade name canesten) for Aspergillus niger,
- Gentamicin 0.3% drops
What is malignant otitis?
Most common causative organism?
Malignant otitis externa is an extension of otitis externa into the bone surrounding the ear canal (i.e. the mastoid and temporal bones). Malignant otitis, without treatment, is a fatal condition. Osteomyelitis will progressively involve the skull and meninges.
Pseudomonas aeruginosa
What are some symptoms and signs of malignant otitis?
Symptoms: Pain and headache, more severe than clinical signs would suggest.
Signs: Granulation tissue at bone–cartilage junction of ear canal; exposed bone in the ear canal. Facial nerve palsy (drooping face on the side of the lesion).
Name two risk factors for malignant otitis
Diabetes
Radiotherapy to head and neck
- Fever
- Enlarged lymph nodes
- Sore throat, pharyngitis, tonsillitis
- Malaise, lethargy
Diagnosis?
Infective mononucleosis
What is the classic triad of infective mononucleosis?
Fever
Pharyngitis
Lymphadenopathy
What are some other symptoms and signs of infective mononucleosis?
Jaundice/hepatitis Rash Haematology - Leucocytosis (lymphocytosis), presence of atypical lymphocytes in blood film Splenomegaly Palatal petechiae
What are some possible complications of infected mononucleosis?
- Anaemia, thrombocytopenia
- Splenic rupture
- Upper airway obstruction
Increased risk of lymphoma, especially in immunosuppressed
Organism responsible for infective mononucleosis?
What are the two phases of primary infection?
Epstein-Barr virus
- Primary infection in early childhood rarely results in infectious mononucleosis
- Primary infection in those >10 years often causes infectious mononucleosis
Treatment for infective mononucleosis?
Bed rest Paracetamol Avoid sport Antivirals not clinically effective Corticosteroids may have a role in some complicated cases
