ENT Microbiology Flashcards
What generally is responsible for causing inflammation of the throat and pharynx?
Infectious causes (2/3rd viral)
(non-infectious causes are rare)
If sore throat and lethargy persist into the second week, and if the patient is 15-25 years old, what should be suspected?
Infectious mononucleosis (glandular fever)
Which pathogen causes infectious mononucleosis?
Epstein barr virus
What is the most common cause of a bacterial sore throat?
Streptococcus pyogenes
What causes the beta haemolysis associated with S. pyogenes?
LMW toxin diffusing out of the colonies
What is “quinsy”?
Peri-tonsillar abscess
When will quinsy normally occur?
Usually a complication of tonsillitis
Streptococci most frequently cause unilateral infection in the palatine tonsils
What is Lemierre’s syndrome?
An infection, most commonly by F. necrophorum, of the posterior compartment of the lateral pharyngeal space as a complication of a bacterial sore throat infection in young, otherwise healthy adults
It involves a triad of symptoms:
- Pharyngotonsillar or odontogenic infection
- Lateral pharyngeal space invasion leading to internal jugular vein thrombosis
- Metastatic disease (sepsis or lung involvement)
(it is also known as human necrobacillosis and postanginal sepsis)
Which condition may result as a complication of an inadequately treated Streptococcus throat infection?
Rheumatic fever
What are the key symptoms of Rheumatic fever?
- Fever
- Arthritis
- Pancarditis
Which condition involving the kidneys can become a late complication of a streptococcus throat infection?
Glomerulonephritis
(presents with haematuria, albuminuria and oedema)
What is the treatment for a bacterial sore throat caused by S. pyogenes?
Penicillin
Which pathogen causes diptheria?
Corynebacterium diphtheriae
How does diptheria affect the posterior pharynx?
Causes severe sore throat
Grey/white membrane across pharynx
What is the treatment for diptheria?
Antitoxin and supportive penicillin/erythromycin
(it is vaccine preventable and rare in the UK)
How does candida present in the throat and mouth?
White patches in red/raw mucous membranes
What causes thrush?
Candida albicans (endogenous)
How can thrush be treated?
Nystatin
What is acute otitis media?
URTI involving middle ear
This happens as the infection passes via the Eustachian tube
How doe acute otitis media typically present?
- Infants/children
- Ear ache
- Discharge (if ear drum ruptures)
(hearing loss, fever and lethargy are also common)
Which bacteria are most commonly found to infect the middle ear?
- Streptococcus pneumoniae
- Haemophilus influenzae
- Streptococcus pyogenes
- Moraxella catarrhalis
How can middle ear infections be diagnosed?
Only by discharge swabs
How are infections of the middle ear treated?
Most resolve spontaneously
1st line - Amoxicillin
2nd line - Erythromycin
What is acute sinusitis?
Mild discomfort over the frontal or maxillary sinuses due to congestion often seen in patients with URTI
What does severe pain and tenderness with purulent nasal discharge indicate in a patient with acute sinusitis?
Secondary bacterial infection
Which bacteria commonly affect the sinuses in acute sinusitis
- Streptococcus pneumoniae
- Haemophilus influenzae
- Streptococcus pyogenes
- Moraxella catarrhalis
How long does acute sinusitis usually last?
2.5 weeks
When should antibiotics be used for acute sinusitis?
Severe or deteriorating cases lasting longer than 10 days
What is the definition of chronic sinusitis?
Sinusitis lasting longer than 4 weeks
(Acute is < 4 weeks)
What is the treatment for acute sinusitis?
1st line - Penicillin
2nd line - Doxycyline (clarithromycin in children)
Why must doxycyline be avoided in children?
It is toxic to growing teeth and bones
What is the term given to inflammation of the outer ear canal?
Otitis externa
Why may hearing be impacted in otitis externa?
Discharge and increased amounts of ear wax may be associated
In the early stages otitis externa will be red and _______
In the early stages otitis externa will be red and itchy
What is malignant otitis?
Extension of otitis externa into the bone surrounding the ear canal
Why is malignant otitis a fatal condition without treatment?
The mastoid and temporal bones are affected by osteomyelitis which will also begin to involve the meninges
What are the symptoms and signs for malignant otitis?
- Pain and headache (worse than signs would suggest)
- Granulation tissue at bone/cartilage junction of ear canal
- Facial nerve palsy
Which pathogen usually causes malignant otitis?
Pseudomonas aeruginosa
What are the key risk factors for malignant otitis?
Diabetes
Radiotherapy to the head/neck
What are the common causes for otitis externa?
Bacterial:
- S. aureus
- Pseudomonas aeruginosa
Fungal:
- Aspergillus niger
- Candida albicans
What should be avoided when affected by otitis externa?
Swimming
(there ear is constantly wet damp with regular swimming increases likelyhood of bacterial growth)
How should fungal otitis externa be treated?
Topical clotrimazole
How is otitis externa treated if the cause is bacterial?
Gentamicin (0.3%) drops
What is the classic triad of symptoms seen in most patients with infectious mononucleosis?
- Fever
- Pharyngitis
- Lymphadenopathy
Where are the lymph nodes often most prominent in infectious mononucleosis?
Neck (cervical)
Why are ampicillin and amoxicillin not recommended to treat infectious mononucleosis?
Cause diffuse rash in many patients
Which LFT is most raised in infectious mononucleosis?
ALT
Which organs are most commonly affected by infectious mononucleosis?
- Respiratory tract
- Skin (rash (25%))
- Liver (jaundice/hepatitis in few patients)
- Spleen (splenomegaly (50%))
- Palate (palatal petechiae)
- Blood (leucocytosis, presence of atypical lymphocytes in blood film)
Atypical lymphocytes can occur with any viral infection, what makes this sign different in infectious mononucleosis?
It occurs in around 15% of lymphocytes
How long does infectious mononucleiosis normally last?
2-4 weeks
Why should sport be avoided for 6 weeks in infectious mononucleiosis?
Splenomegaly many occur with the condition and sport may induce a rupture
What are the main complications associated with infectious mononucleiosis?
- Anaemia
- Thrombocytopenia
- Splenic rupture
- Upper airway obstruction
- Increased risk of lymphoma
What is different about Epstein barr infection in those in early childhood versus those over 10 years old?
Primary infection in early childdhood is unlikely to cause infectious mononucleiosis, whereas after 10 years it is likely
What are the two phases for EBV acquisition?
1-6 years
14-early 20s
Why may EBV induce autoimmunity?
The virus replicates in B cells which leads to abnormal antibody production
What is the treatment for infectious mononucleiosis?
Bed rest
No sport
Paracetamol
Corticosteroids in severe cases
Which pathogens can cause similar infection to infectious mononucleiosis?
- Cytomegalovirus
- Toxoplasmosis
- Primary HIV infection
How can infectious mononucleiosis be differentiated from primary HIV infection?
Risks in history
Presence of diarrhoea (in HIV)
Which type of virus commonly causes oral lesions?
Herpes simplex type 1
How can primary gingivostomatitis be treated?
Aciclovir
Why is HSV1 likely to reactivate?
Inactive virus can remain latent in trigeminal ganglia
What is herpetic whitlow?
Llesion (whitlow) on a finger or thumb caused by the herpes simplex virus
Which pathogen causes herpangina?
Coxsackie viruses
Which pathogen causes hand, foot and mouth disease?
Coxsackie viruses
Which systemic diseases may cause recurrent apthous ulcers?
Behcet’s disease
Gluten sensitive enteropathy or IBD
Reiter’s syndrome
Drugs reactions
Skin diseases (lichen planus, pemphigus or pemphigoid)
Which pathogen cause syphilis?
Treponema pallidum
How does primary syphilis present?
Chancre (painless ulcer) at site of entry
