Microbiology of ENT Infections Flashcards
What are some viral causes of oral ulceration?
Herpes simples virus, primary gingivostomatitis due to HSV1, cold sore, herpangina, hand/foot and moth disease, primary syphilis
What types of herpes simplex virus are usually associated with oral ulceration?
Types 1 and 2 = type 1 acquired in childhood and most commonly associated with oral ulceration
How does herpes simplex infection spread?
Through saliva contact
What age group is most at risk of developing primary gingivostomatitis due to HSV1?
Pre-school children (usually primary infection)
What do children with primary gingivostomatitis due to HSV1 present with?
Systemic upset, fever, local lymphadenopathy, vesicles of 1-2mm, ulcers
Where do the lesions from primary gingivostomatitis occur?
Lips, buccal mucosa, hard palate = may spread beyond mouth
How is primary gingivostomatitis due to HSV1 treated?
Aciclovir = may take up to 3 weeks to recover
What occurs in viral latency?
After primary infection inactive form of virus hides in sensory nerve cells = can reactivate to re-infect mucosal surfaces
What causes cold sores?
Reactivation of latent virus from nerves causes active infection (due to various stimuli)
Are all reactivations of cold sores symptomatic?
No = may be silent reactivation
How are cold sores treated?
Aciclovir or suppression = acyclovir doesn’t prevent latency
What is the natural history of cold sores?
Multiple cycles of latency and active infection are possible, decreasing frequency over time, only 50% of infected people get clinical recurrences
What virus is normally responsible for cold sores?
Oral herpetic lesions usually HSV1
Recurrent intra-oral lesions rarely HSV
How is HSV confirmed in the lab?
Swab of lesion in virus transport medium = detection of viral DNA by PCR
Where do lesions occur in herpangina?
Vesicles/ulcers on soft palate
What age group normally suffers form herpangina?
Pre-school children
What causes herpangina?
Coxsackie viruses = usually enterovirus
How are herpangina and hand, foot and mouth disease diagnosed?
Clinically or by PCR test of swab in viral transport medium
What causes hand, foot and mouth disease?
Coxsackie viruses = usually enterovirus
Family outbreaks common (child usually first infected)
What is the primary lesion of syphilis called?
Chancre = usually at site of entry of bacterium
How does primary syphilis present?
Painless indurated ulcer at site of entry = most common site is genitals, but may be oral lesion
What bacteria causes primary syphilis?
Treponema pallidum
What happens if syphilis is left untreated?
Can progress to secondary and tertiary syphilis
What are aphthous ulcers?
Non viral, self limiting but recurrent painful ulcers of mouth =round/ovoid, have inflammatory halo
What are some features of aphthous ulcers?
Confined to mouth and no systemic disease, each ulcer lasts about 3 weeks, begin in childhood and tend to ablate in 30s
What are some systemic diseases that cause oral ulcers?
Bechet’s disease, coeliac, IBD, Reiter’s disease, drug reactions, skin disease
How does Bechet’s disease present?
Recurrent oral ulcers, uveitis and genital ulcers
May involve visceral organs (i.e heart, lungs, MSK etc)
What additional symptoms has a patient with oral ulceration due to coeliac or IBD have?
Diarrhoea and weight loss
What normally accompanies the oral ulcers of Reiter’s disease?
Arthritis
What are some skin diseases that may cause oral ulceration?
Lichen planus, pemphigus, bullous pemphigoid
What age groups are mostly affected by acute throat infections?
Children aged 5-10 and young people aged 15-25
Inflammation of what structures usually causes pain at the back of the throat?
Acute pharyngitis = inflammation of part of throat behind soft palate
Tonsillitis = inflammation of tonsils
What age group is commonly affected by infectious mononucleosis?
Young people aged 15-25
What are some rarer causes of an acute sore throat that should always be considered?
HIV (especially seroconversion), gonococcal pharyngitis, diphtheria
What are some non-infectious causes of an acute sore throat?
Largely uncommon = GORD, irritation from smoking, alcohol or hay fever
Are throat swabs routinely done to investigate sore throats in primary care?
No
In what situation would a patient with a sore throat be admitted to hospital as an emergency?
Sore throat with stridor or respiratory distress = attempts to examine throat should be avoided
What is the natural history of most sore throats?
Self limiting regardless of cause = resolves in 3 days in 40%
What are some complications associated with an acute sore throat?
Otitis media (most common), peri-tonsillar abscess (quinsy), para-pharyngeal abscess, mastoiditis
How are sore throats managed?
Self-care advice, antibiotics if needed, identify those who are immunosuppressed or who need admission
When would a sore throat be suspected as being a sign of throat cancer?
If sore throat persistent, especially if there is a neck mass
When should patients with a sore throat be admitted to hospital or referred to a specialist?
Suspected throat cancer
Sore/painful throat for 3-4 weeks = pain on swallowing/dysphagia for >3 weeks
Red/red on white patches or ulceration/swelling of oral/pharyngeal mucosa for >3 weeks
What are some self-care treatments for patients with sore throats?
Analgesia = paracetamol, ibuprofen
Medicated lozenges, avoid hot drinks, adequate fluid intake, mouthwashes/sprays (less evidence)
What is responsible for 2/3 of sore throats?
Viral infection = don’t need antibiotics
What is the most common cause of a bacterial throat infection?
Strep pyogenes (group A strep)
What does strep pyogenes infection of the throat cause?
Acute follicular tonsillitis = treated with penicillin
What are some late complications of strep pyogenes infection of the throat?
Rheumatic fever and glomerulonephritis
When does rheumatic fever present after a strep pyogenes infection of the throat?
3 weeks post sore throat = fever, arthritis, pancarditis
When does glomerulonephritis present after a strep pyogenes throat infection?
1-3 weeks post sore throat = haematuria, albuminuria, oedema
How is the CENTOR criteria for assessing the risk of strep pyogenes infection of the throat scored?
I point for each, out of 4, developed for adults but used widely = 0,1 or 2 has 3-17% risk, 3 or 4 has 32-56% risk
What are the categories in the CENTOR criteria for assessing the risk of strep pyogenes infection of the throat?
Tonsillar exudate, tender anterior cervical lymph nodes, history or fever >38, absence of cough
What age group is most at risk of strep pyogenes throat infections?
Children aged 5-15 years old (less likely outside this age range)
How is the fever PAIN criteria scored for assessing the risk of strep pyogenes infection of the throat?
One point for each, not validated for use in children <3 = 0 or 1 has 13-18% risk, 2 or 3 has 34-40% risk, 4 or 5 has 62-65% risk
What makes up the fever PAIN criteria for assessing the risk of strep pyogenes infection of the throat?
Fever (lasts 24hrs), purulence, attend rapidly (within 3 days), inflamed tonsils, no cough/coryza
What must be done before prescribing a DMARD?
Take full blood count
What should be done if a patient on a DMARD has a low white cell count or is deteriorating?
Seek specialist advice, stop DMARD, provide symptomatic relief, consider antibiotics
What are some causes of neutropenia?
Carbimazole, chemotherapy, leukaemia, asplenia, aplastic anaemia, HIV with low CD4
What should be done in patients with neutropenia?
Get urgent full blood count and withhold drug suspected of causing it
When should phenoxymethlypenicllin be considered to treat strep pyogenes throat infections?
If fever PAIN score 4 or 5
If CENTOR criteria score 3 or 4
What is the causative organism of diphtheria?
Corynebacterium diphtheriae = produces potent exotoxin which is cardio/neuro-toxic
What does diphtheria present with?
Sore throat with grey/white membrane across pharynx
Is there a vaccine for diphtheria?
Yes = cell-free purified toxin from Corynebacterium diphtheriae (toxoid vaccine)
Is diphtheria common?
No = rare in UK (but higher incidence in Russia)
How is diphtheria treated?
Antitoxin and supportive measures, penicillin/erythromycin
What is the other name for infectious mononucleosis?
Glandular fever
How does infectious mononucleosis present?
Fever, enlarged lymph nodes, sore throat, pharyngitis, tonsillitis, malaise, lethargy
What is the prognosis of infectious mononucleosis?
Protracted but self-limiting disease
What are some rarer signs and symptoms that can occur due to infectious mononucleosis?
Jaundice/hepatitis, rash, leucocytosis (lymphocytosis), atypical lymphocytes on blood film, splenomegaly, palatal petechiae
What are some complications associated with infectious mononucleosis?
Anaemia, thrombocytopenia, splenic rupture, upper airway obstruction, increased risk of lymphoma (especially in immunosuppressed)
What causes infectious mononucleosis?
Epstein Barr virus = establishes persistent infection in epithelial cells (notably in pharynx)
What are the two phases of primary infection of infectious mononucleosis?
Early childhood = rarely causes infectious mononucleosis
Age >10 years = often causes infectious mononucleosis
What is the therapy for infectious mononucleosis?
Bed rest, paracetamol, avoid sport, no antivirals, corticosteroids if complicated
How can infectious mononucleosis be confirmed in the lab?
EB virus IgM, heterophile antibody (Paul-Bunnell test, monospot test), blood count and film, LFTs
What are other infectious agents that may cause symptoms similar to those of infectious mononucleosis?
Cytomegalovirus, toxoplasmosis, primary HIV infection
What causes candida/thrush?
Candida albicans is causative agent
Risk factors = post antibiotics, immunosuppression, smoking, inhaled steroids
When should candida/thrush be investigated?
If recurrent
How does candida/thrush present?
White patches on red, raw mucous membranes in throat/mouth
How is candida/thrush treated?
Nystatin or fluconazole
What is acute otitis media?
Upper respiratory infection involving middle ear by extension of infection up the Eustachian tube
What age group is acute otitis media most common in?
Predominantly disease of infants and children
What does acute otitis media present with?
Ear ache
What is the most common cause of acute otitis media?
Often viral with secondary bacterial infection
What are some bacteria commonly implicated in acute otitis media?
H. influenzae, strep, pneumoniae, strep, pyogenes
When should a swab be taken to diagnose acute otitis media?
Only if the eardrum perforates (can’t gain access otherwise)
How is acute otitis media treated?
80% resolve in 4 days without antibiotics
First line is amoxicillin
Second line in erythromycin
What is malignant otitis externa?
Extension of the otitis externa into the bone surrounding the ear canal
What is the prognosis of untreated malignant otitis externa?
Fatal if untreated = osteomyelitis will progressively involve skull and meninges
What are the symptoms of malignant otitis externa?
Pain and headache, more sever than clinical signs would suggest
What occurs in malignant otitis externa?
Granulation tissue at bone-cartilage junction of ear canal, exposed bone in ear canal, facial nerve palsy (drooping of face on side of lesion)
What investigations are done for malignant otitis externa?
PV/CRP, imaging, biopsy, culture
What organism causes malignant otitis externa?
Usually pseudomonas aeruginosa
What are the risk factors of malignant otitis externa?
Diabetes, radiotherapy of head and neck
What is otitis externa?
Inflammation of the outer ear canal
How does otitis externa present?
Redness and swelling of skin of ear canal, sore and painful, discharge or increased ear wax, may be itchy in early stages
How does hearing become impaired in otitis externa?
If canal becomes blocked by swelling or secretions
What are some bacterial causes of otitis externa?
Staph. aureus, proteus spp, pseudomonas aeruginosa
What are some fungal causes of otitis externa?
Aspergillus niger, candida albicans
How is otitis externa managed?
Topical aural toilet and swab for microbiology
When are antimicrobials used to treat otitis externa?
In unresponsive or severe cases
What are some antimicrobials used to treat otitis externa?
Depends on culture result = topical clotrimazole (canestan) for aspergillus niger, gentamicin 0.3% drops
How does acute sinusitis present?
Mild discomfort over frontal/maxillary sinuses due to congestion
What group of patients normally suffer from acute sinusitis?
Seen in patients with URT viral infections
What would indicate a secondary bacterial infection in acute sinusitis?
Severe pain and tenderness with purulent discharge
What organisms cause acute sinusitis?
Similar to those that cause acute otitis media
How long does acute sinusitis usually last?
Two and a half weeks
When should antibiotics be given to treat acute sinusitis?
For severe or deteriorating cases of >10 days duration
What antibiotics are used to treat acute sinusitis?
First line = phenoxymethlypenicllin
Second line = doxycycline (not in children)
