Microbiology Flashcards
Sore throat, with what else, should be immediately referred to hospital and not examined?
Stridor or respiratory difficulty
Pain at the back of the mouth is most likely to be which conditions?
Tonsilitis or pharyngitis
What is acute pharyngitis?
Inflammation of the oropharynx
Most cases of tonsillitis and pharyngitis are caused by what?
Viruses
What age groups are most likely to present with tonsillitis/pharyngitis?
5-10 and 15-25
Should throat swabs be carried out routinely in primary care? Why/why not?
No- they will most likely just show commensals
If a sore throat and lethargy persists into a second week, what should be suspected? (Especially if the individual is 15-25)
Infectious mononucleosis
What are some indications for a referral in an individual with a sore throat?
Suspicion of cancer, sore throat for 3-4 weeks, dysphagia/odynophagia for > 3 weeks, stridor or respiratory difficulty
If tonsillitis/pharyngitis is bacterial, what is the most likely cause?
Group A strep (strep pyogenes)- strep throat
What 4 factors (Centor criteria) increase the likelihood of a sore throat being caused by GAS?
Tonsillar exudates, anterior cervical lymphadenopathy, no cough, fever
Strep throat is most likely in what age group?
5-15
What should always be checked in an immunocompromised person with a sore throat?
FBCs
If GAS is found to be the cause of a sore throat, what should it be treated with?
Penicillin
Patients with GAS throat infections should really be isolated until they have been on antibiotics for how long?
48 hours
What are 3 late complications of a GAS sore throat?
Rheumatic fever, glomerulonephritis, peritonsillar abscess
How will rheumatic fever present, post GAS throat infection?
3 weeks after- fever, arthritis, pancarditis
How will glomerulonephritis present, post GAS throat infection?
1-3 weeks after- haematuria, albuminuria, oedema
What organism causes diphtheria?
Corynebacterium diphtheriae
How will diphtheria present?
Severe sore throat with a grey/white membrane across the pharynx
Describe the toxin produced in diphtheria?
Potent exotoxin- cardio/neurotoxic
How should diphtheria be treated?
Vaccination, anti-toxins and supportive penicillin/erythromycin
What organism causes oral thrush? Where does this come from?
Candida albicans- this is a commensal (endogenous cause)
How will oral thrush present?
White patches on red raw mucus membranes
How should oral thrush be treated?
Nystatin
What forms the classic triad of infectious mononucleosis?
Fever, enlarged lymph nodes, pharyngitis
Apart from those in the classic triad, what are some other symptoms of infectious mononucleosis?
Malaise, lethargy, jaundice, rash, splenomegaly, abnormal haematology
What may make the rash in infectious mononucleosis worse?
Amoxicillin (do not prescribe)
What is the most classic abnormal haematology in infectious mononucleosis?
Atypical lymphocytes (large and irregular)
What is the onset of infectious mononucleosis? How long can it last? How is it treated?
Insidious over several days, can last 4 weeks, self-limiting with supportive treatment
What are the risks of infectious mononucleosis?
Anaemia, thrombocytopenia, splenic rupture, upper airway obstruction
There is an increased risk of what with infectious mononucleosis, especially in the immunocompromised?
Lymphoma
What is the cause of infectious mononucleosis?
Epstein barr virus
Epstein barr is a virus of what family? It causes a persistent infection where?
Herpes family- infection in epithelial cells, especially of the pharynx
What are the 2 phases of primary infection with EBV?
Primary infection in childhood, rarely causing glandular fever. Primary infection > 10 years, often causing glandular fever
Are antivirals effective in glandular fever?
No
For how long should sport be avoided after glandular fever? Why?
6 weeks- risk of splenic rupture
What is the main investigation for glandular fever? What other tests would you do?
EBV IgM (serology). Also blood count and film, and LFTs
The Paul Bunnel and Monospot tests can be used to diagnose what?
Infectious mononucleosis
What are the 2 extra points on the modified Centor criteria?
Aged < 15 add one point, aged > 44 subtract one point
What is the management for a sore throat with a Centor criteria of < 2?
No antibiotic or throat culture necessary
What is the management for a sore throat with a Centor criteria of 2-3?
Throat culture and treat with antibiotics if positive
What is the management for a sore throat with a Centor criteria of > 3?
Empirical antibiotics
What antibiotics should NEVER be given in infectious mononucleosis?
Ampicillin/amoxicillin
What is acute otitis media?
URTI involving the middle ear by extension of infection up the eustachian tube
Acute otitis media is primarily a disease of who?
Children and infants
How will patients with acute otitis media present?
EARACHE, discharge, hearing loss, fever and lethargy
Infections of the middle ear are often caused by what? There is often what afterwards?
Caused by a virus, followed by a secondary bacterial infection
What are the most common bacteria causing acute otitis media?
Strep pneumoniae, haemophilus influenzae, moraxella catarrhalis, strep pyogenes
How can you test for the cause of acute otitis media?
Swab of pus if the eardrum perforates (if this hasn’t happened then you cannot test)
How soon does acute otitis media usually resolve?
Within 4 days without antibiotics
If antibiotics are required for otitis media, what are the 1st and 2nd line choices?
1st = oral amoxicillin, 2nd = oral erythromycin
What is the usual presentation of acute sinusitis?
Mild discomfort over the frontal or maxillary sinuses due to congestion
Acute sinusitis is often seen in patients with what?
URTI
What indicates a secondary bacterial infection of acute sinusitis?
Severe pain and tenderness with purulent nasal discharge
Are samples taken for acute sinusitis? What are the organisms likely to be?
No samples, organisms are the same as for otitis media
What defines acute and chronic sinusitis?
Acute = < 4 weeks, chronic = > 4 weeks
What is the average length of acute sinusitis? Antibiotics should be preserved for who?
2.5 weeks, antibiotics should be given to severe, deteriorating cases of > 10 days
What is the 1st line antibiotic for acute sinusitis?
Penicillin V
What is the second line antibiotic for acute sinusitis? Who can this not be used in?
Doxycycline, can’t be used in children
How long should treatment fro acute sinusitis last?
10 days
Otitis externa is common in who?
Swimmers
What are some symptoms of otitis externa?
Redness and swelling, pain and discharge, itch and maybe affected hearing
What is malignant otitis?
A type of otitis externa which extends into the bone surrounding the ear canal (mastoid and temporal bones)
Why is malignant otitis fatal without treatment?
Osteomyelitis will eventually involve the skull and meninges
What are some symptoms of malignant otitis?
Pain and headache, more severe than clinical signs would suggest. May be facial nerve palsy.
In malignant otitis, what may be found at the bone-cartilage junction?
Granulation tissue
What are some investigations for malignant otitis?
Inflammatory markers, radiological imaging, biopsy and culture
What organism is usually the cause of malignant otitis?
Pseudomonas aeruginosa
What are some risk factors for malignant otitis?
Diabetic, radiotherapy to the head and neck, immunocompromised
What are the main bacterial causes of otitis externa?
Staph aureus and pseudomonas aeruginosa
What are the main fungal causes of otitis externa?
Aspergillus niger and Candida albicans
What is the most common management for otitis externa?
Topical aural toilet
What is the investigation for otitis externa? What is the relevance of this?
Swabs to microbiology- preserve an antibiotic for unresponsive or severe cases
If a fungal cause of otitis externa is to be treated, what is used?
Topical clometrizole and cleaning of the ear
If a bacterial cause of otitis externa is to be treated, what is used?
Gentamicin 0.3% drops and cleaning of the ear
Which type of herpes simplex is the cause of oral lesions? What is the main infection here?
Type 1- primary gingivostomatitis
How is herpes simplex transmitted?
Saliva content
How long does primary gingivostomatitis last for? How can it be treated?
Can last for 3 weeks, treat with acyclovir
Wheres does herpes simplex establish latency?
Trigeminal ganglia
Herpetic whitlow is an occupational hazard of what?
Dentistry and anaesthetics
How is HSV confirmed?
PCR
What causes herpangina, and hand, foot and mouth disease?
Coxsackie (enterovirus)
Who does herpangina typically present in? How is it tested for?
Children- test with PCR (or just clinical diagnosis)
How is coxsackie (enterovirus) spread?
Faecal oral
Describe aphthous ulcers?
Recurrent painful ulcers at the back of the mouth that are round and have inflammatory haloes.
Are aphthous ulcers systemic?
No, confined to the mouth with no other symptoms
How long do aphthous ulcers recur for? How long does a single ulcer last?
Childhood- 3rd decade. A single ulcer will last < 3 weeks
What is Behcets disease?
Recurrent oral and genital ulcers with uveitis (can also involve visceral organs)
Where is Behcets disease most common?
Middle East and Asia
Apart from Behcets disease, what are some other causes of recurrent ulcers in association with systemic disease?
Coeliac disease, IBD, Reiter’s syndrome, drug reactions, skin disease
Why should penicillin be used over amoxicillin?
Less toxic
Why would amoxicillin be used over penicillin?
Better oral absorption, broader spectrum
Where is aspergillus normally found?
In the environment (not swimming pool water!)
What is worrying about invasive aspergillus?
Neutropenic post-chemotherapy and those with COPD
What are the 4C antibiotics?
Clindamycin, cephalosporins (cefriaxone), co-amoxiclav, ciprofloxacin
What antibiotics should be given in orbital cellulitis?
IV ceftriaxone, flucloxacillin and metronidazole
What is the biggest concern with orbital cellulitis?
Cavernous sinus thrombosis
What is myringitis?
Inflammation of the tympanic membrane
