Microbiology Flashcards
Who is most likely to get an acute throat infection?
children aged 5–10 years
young adults aged 15–25 years
If sore throat and lethargy persist into the second week, especially if the person is 15-25years of age what should be suspected?
Glandular fever (infectious mononucleosis)
When would a sore throat be referred?
- Persistent sore throat, with neck mass (cancer)
- Sore throat lasts for 3 to 4 weeks
- pain on swallowing/dysphagia for >3 weeks
- Red or white patches/ulceration/swelling of the oral/pharyngeal mucosa persists for >3 weeks
- Stridor / respiratory difficulty is an emergency
What is the most common bacterial cause of acute follicular tonsillitis?
Streptococcus pyogenes
Group A Beta Haemolytic Strep)
What is bacterial tonsillitis treated with?
Penicillin
A patient with strep. pyogenes tonsillitis should be isolated until they have been on antibiotics for 48 hrs. TRUE/FALSE?
TRUE
Droplet precautions should also be taken as patient can spread infection by coughing
What are the late complications of strep. throat?
- Rheumatic fever (3 weeks after)
- Glomerulonephritis (1-3 weeks after)
How does diptheria present in the throat?
severe sore throat with a grey white pseudomembrane across the posterior pharynx
Why is the diptheria exotoxin particularly dangerous during infection?
cardiotoxic and neurotoxic
What complications can the diptheria pseudomembrane cause?
Can obstruct the airway
What is the diptheria vaccine made of?
cell-free purified toxin extracted from a strain of C. diphtheriae
=> a toxoid vaccine
What is the treatment for diptheria?
antitoxin and supportive and penicillin / erythromycin
antibiotics dont make much difference on their own - the anti-toxin is important in treatment
What microbe is known to cause oral thrush?
Candida albicans
How does oral thrush appear in the mouth
white patches on red, raw mucous membranes in throat/ mouth
How is oral thrush treated?
nystatin or fluconazole
What is otitis media?
upper respiratory infection involving the middle ear by extension of infection up the Eustachian tube
Who usually gets otitis media?
infants and children
Present with earache
What bacteria usually infect the middle ear?
Streptococcus pneumoniae
Haemophilus influenzae
Streptococcus pyogenes
Moraxella
Are middle ear infections usually bacterial or viral?
Viral but often with secondary bacterial infection
Can the middle ear be swabbed for culture?
Swab of pus taken if eardrum perforates to release it – otherwise samples can’t be obtained
What treatment is most commonly used for infections of the middle ear?
80% resolve in 4 days without antibiotics.
1st line – amoxicillin
2nd line – erythromycin
What is the most common presenting feature in acute sinusitis?
Mild discomfort over frontal or maxillary sinuses due to congestion
Severe pain and tenderness with purulent nasal discharge in acute sinusitis indicates what?
Secondary bacterial infection
What cases of sinusitis should antibiotics be reserved 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
How does otitis externa usually present?
- Red/swollen ear canal skin
- May be itchy
- Can become sore and painful
- May be discharge, or increased ear wax
- Canal becomes blocked = hearing affected
What is Malignant otitis externa?
extension of otitis externa into the bone surrounding the ear canal (i.e. the mastoid and temporal bones
Why can Malignant otitis externa be fatal?
Osteomyelitis can erode into skull and meninges
What signs can indicate malignant otitis externa?
- 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)
What bacteria usually cause malignant otitis externa?
Staph aureus
Pseudomonas aeruginosa
What can predispose to malignant otitis externa?
diabetes and radiotherapy to head and neck
What fungal infections can cause otitis externa?
Aspergillus niger (black spores visible) Candida albicans
What are the main symptoms in glandular fever?
Fever
Enlarged lymph nodes
Sore throat, pharyngitis, tonsillitis
Malaise, lethargy
What rarer signs can be seen in glandular fever?
Jaundice/hepatitis Rash Leucocytosis (lymphocytosis) Presence of atypical lymphocytes in blood film Splenomegaly Palatal petechiae
What complications can arise from glandular fever?
- Anaemia, thrombocytopenia
- Splenic rupture (warn pt if they do contact sport)
- Upper airway obstruction
- Increased risk of lymphoma, especially in immunosuppressed
What virus causes infectious mononucleosis (glandular fever)?
Epstein-Barr virus (one of herpes family)
Primary infection in early childhood rarely results in infectious mononucleosis. TRUE/FALSE?
TRUE
but infection >10 often results in getting the infection
What is the treatment for infectious mononucleosis?
Bed rest Paracetamol Avoid sport Antivirals not clinically effective Corticosteroids may have a role in some complicated cases
What lab investigations can assist in the diagnosis of glandular fever?
Epstein-Barr virus IgM
Heterophile antibody
Blood count and film
Liver function tests
What other viruses cause illness similar to that of infectious mononucleosis?
Cytomegalovirus
Toxoplasmosis
Primary HIV infection
seroconversion illness
What is the CENTOR criteria for distribution of antibiotics in tonsillitis?
(1 point for each => need 3/4 for antibiotics)
- Tonsillar exudate
- Tender anterior cervical lymph nodes
- Fever of >38
- Absence of cough
What is the FEVER PAIN criteria for antibiotics in tonsillitis?
Fever in last 24hrs? Purulence? Attend rapidly? (within 3 days) Very inflamed tonsils No cough/cold
How should patients on DMARDs with a suspected throat infection be managed?
FBC
withhold DMARD whilst waiting on blood results
When is Herpes simplex Type 1 usually acquired?
Childhood
What symptoms usually present in a Primary gingivostomatitis due to HSV1 infection?
Ulcerating lesion
Local lymphadenopathy
Fever
How long does it take to recover from a Primary gingivostomatitis (HSV1) infection?
3 weeks
How is Primary gingivostomatitis in HSV1 treated?
Aciclovir
Where does the herpes simplex virus usually lie latent?
Trigeminal ganglion
Everyone who gets a primary HSV1 infection wll get recurrence. TRUE/FALSE?
FALSE
but factors such as immunosuppression can increase risk of recurrence
HSV2 is more likely to recur than HSV1. TRUE/FALSE
TRUE
and more related to genital infection
What is the potentially dangerous complication of the herpes simplex virus?
HSV encephalitis - temporal lobe necrosis
What is herpangina?
Vesicles/ulcers on soft palate
What virus causes herpangina?
Coxsackie
What other condition is caused by coxsackie virus?
Hand, foot and mouth
Why do GPs commonly not do viral swabs for hand, foot and mouth?
Nothing else similar presents in the same age range
usually children - can cause family outbreaks
What are aphthous ulcers?
Non viral
Recurring painful ulcers of the mouth
Round or ovoid shape
Have inflammatory halos
What systemic disease can cause recurrent ulcers?
Behçet's disease Coeliac or IBD Reiter’s disease Drug reactions Skin diseases
WHat is a Chancre and what condition is it seen in?
- Painless ulcer at site of entry of bacterium Treponema pallidum (usually genitals or oral)
- Syphilis infection