Infections of the Sensory System Flashcards
Give a general overview of the defensive mechanisms within the body?
Non specific defences (innate immunity);
First line of defence - Skin
- Mucous membranes
- Secretions of skin and membranes
Second line of defence;
- Phagocytic leukocytes
- Antimicrobial proteins
- Inflammatory response
- Fever
Specific Defences;
Third line of defence;
- Lymphocytes
- Antibiotics
- Memory cells
What are the ocular defence mechanisms?
Innate defence;
- Eyelids
- Tears + Mucin
- Ocular Epithelium
- Ocular Bacterial Flora
- Antibacterial Factors (enzymes)
- Macrophages and NK cells
Adaptive Defence;
- Eye-associated lymphoid tissue
- Langerhan’s cells (in tear ducts)
- Immunoglobulins
- T-lymphocytes
- B-lymphocytes
What is an important first line in defence for the orbit?
Bony orbit - protects globe and accessory organs, floors maxillary and ethmoid sinus
What has high pressure caused in this CT scan?
Left “blow-out” fracture to the orbital floor with contents herniating into maxillary sinus
High pressure - can be caused by sinusitis and blowing nose hard, usually from trauma, eye ball falls into axillary sinus, falls into sinus, allows infection to come up into orbit
What are the 1st-3rd line defence mechanisms in the tear film & cornea?
Innate;
Physical barrier (1st line)
Chemicals and cells (2nd line) ( Lacrimal)
3rd line (adaptive) - Ocular lymphoid tissue working with lacrimal gland to recirculate lymphocytes around the eye!
What is Lysozyme and its function?
Lysozyme is an enzyme that cleaves peptidoglycans;
- Tears
- Salvia
- Mucous
- Macrohages
- Neutrophils
Peptidoglycans are found in bacteria - cleaves this
Peptidogylcans are good against gram positive hard against gram negative (needs support to break outer membrane then get into peptidoglycan)
What is Lactoferrin?
Lactoferrin bings iron - starves bacteria and fungi and blocks viral lipoprotein bonds - anti-viral
- Tears
- Saliva
- Mucous
- Neutrophils
Lysozyme and lactoferrin work together to help to defeat gram negative bacteria. Lactoferrin alters the permeability of the lipopolysaccharide layer giving lysozyme access to the peptidoglycan layer which will go on to break down the peptidoglycan layer and kill the bacteria.
What can you find in the ocular biome?
- Staphylococcus
- Streptococcus
- Propionibacterium
- Corynebacterium
These inhibit growth of pathogenic organisms as they are in competition for the same resources
What are the most common eye infections?
Common eye infections;
- Conjunctivitis (adult & neonate)
- Keratitis (Viral, bacterial)
- Onchocerciasis (parasitic infection)
- Orbital Cellulitis (pre and post-septal)
What are some more rare eye infections ?
Rare eye infections;
- Retinochoroiditis (HIV/AIDS/Toxoplasma)
- Endophthalmitis (post-op and endogenous)
What are the 4 types of conjunctivitis ?
- Common viral conjunctivas
- Adenovirus related conjunctivitis
- Common Bacterial conjunctivitis
- Neonatal conjunctivitis
What are the features of Common Viral Conjunctivitis ?
Common Viral Conjunctivitis
Similar pathogens to a ‘cold’;
- Coronavirus
- Rhinovirus
- Respiratory Syncytial virus
- Parainfluenza
Symptoms;
- Sticky eyes
- Watery
- Pink (conjunctival erythema)
- Discomfort / itchy eyes (Viral itchier more gritty)
- Self limiting (we don’t need to do much for 1 week)
- Rarely cause any serious damage
Usually follow having on of these or after someone in house has one
Bathe eyes, use cold compress, use paracetamol for pain, sterile or boiling water once cooled down
Usually starts in 1 eye then spreads to other as people itch
What are the features of Adenovirus Conjunctivitis ?
- Bilateral, very sticky, red, painful
- Enlargement of ipsilateral periacular lymph node
- Sore throat and cough - miserable
- May have corneal involvement - Punctate keratitis
- Symptomatic treatment
- Punctate keratitis can last a long time
Visual blurring due to punched out bits of cornea
6-8 weeks to go away
What are the features of bacterial conjunctivitis?
Much like viral but;
- Discharge more yellow and thick
- Will not typically go away unless given antibiotics
Cause;
- Haemophilius influenzae
- Streptococcus pneumoniae
- Moraxella
Treatment;
- Chloramphenicol
- Fusidic Acid
What are the features of bacterial conjunctivitis?
Much like viral but;
- Discharge more yellow and thick
- Will not typically go away unless given antibiotics
Cause;
- Haemophilius influenzae
- Streptococcus pneumoniae
- Moraxella
Treatment;
- Chloramphenicol
- Fusidic Acid
What are the features of bacterial conjunctivitis?
Much like viral but;
- Discharge more yellow and thick
- Will not typically go away unless given antibiotics
Cause;
- Haemophilius influenzae
- Streptococcus pneumoniae
- Moraxella
Treatment;
- Chloramphenicol
- Fusidic Acid
What are the features of bacterial conjunctivitis?
Much like viral but;
- Discharge more yellow and thick
- Will not typically go away unless given antibiotics
Cause;
- Haemophilius influenzae
- Streptococcus pneumoniae
- Moraxella
Treatment;
- Chloramphenicol
- Fusidic Acid (eye drops)
How can HIV/AIDS manifest ocularly?
Toxoplasmosis and Cytomegalovirus retinalis
Retinocortical lesions
Parasite most common for living in cat faeces
More detrimental to those with weakened immune system
Can cause spontaneous miscarriage so pregnant people should avoid cleaning up cat litter
What are the features of cytomegalovirus retinalis?
Occurs during late HIV disease
Treatment – antiviral Gancicilovir
What are the features of Otitis Media?
- Most common in infants and small children, 50% viral in origin – mainly RSV
- But also S.pneumoniae and H.influenzae
- Pulling at ears, red ears, fever, crying, poor feeding, restlessness
- May result in hearing difficulties and delayed learning development
What are the features of Mastoiditis?
- A severe complication of Otitis media
- Spread of infection from middle ear to mastoid aircells via mastoid antrum
- Symptoms include; ongoing or recent AOM, redness, tenderness and pain behind the ear, pushed forward pinna, fever, fatigue
- Treatment – if child or unwell referral to ENT in -patient for IV antibiotics and investigation including imaging / blood tests
What are the features of Sinusitis?
Typically maxillary, facial ethmoidal infection
- Pathogen invasion of the air spaces with the URT
- Mucosal swelling prevents muco-cillary clearance of infection
- Exacerbated by local accumulation of inflammatory bacterial products
- Typically follows a common cold so symptoms getting worse and not better around 5 days or continuing for more than 10 days
- Symptoms: nasal blockage or discharge with facial pain/pressure +/- loss of smell
- Treatment – typically self-limiting 2-3 weeks, little evidence for antibiotics
What are the features of tonsillitis ?
Inflammation of the tonsils - typically palatine. Can be viral or bacterial. Therefore - may or may not need antibiotics
Symptoms: Dysphagia, odynophagia, cervical lymphadenopathy, fever
90% of cases will resolve in 7 days without treatment
If have more than 7 times in 1 year, 5 times each year can get tonsillectomy but NHS try to not do
How is Fever PAIN scored?
A score of 0-1 is associated with 13-18% isolation of streptococcus (close to background carriage rates)
- No antibiotics recommended
A score of 2 is associated with 30 - 35% isolation of streptococcus
- Delayed antibiotic may be appropriate
A score of 3 is associated with 39-48% isolation of streptococcus
- Delayed antibiotic may be appropriate
A score of 4 or more is associated with 62-65% isolation of streptococcus
- Consider antibiotics if symptoms,ptoms severe or a short delayed prescribing strategy may be appropriate (48 hours)
What are the features of a Quinsy - “Peritonsillar abscess”?
Collection of pus between the tonsillar capsule and superior constrictor muscle
Complication of untreated bacterial pharyngitis / tonsillitis
Symptoms: fever, pain, trismus, general malaise
Signs: Hot-potato voice, unilateral swelling, deviation of uvula
Management: Same day hospital admission to ENT
- Needle aspiration / drainage, IV antibiotics (penicillin based) and IV steroids, analgesia and IV fluids until oral route available
Complications; Retropharyngeal or deep neck space infection in fascial planes of neck
What are the features of Glandular Fever?
Glandular Fever: Epstein-Barr Virus (EBV)
Swollen tonsils and uvula, petechiae on soft palate, white exudate
Replicated in B lymphocytes
Clinical features;
- Fever
- Headache
- Malaise
- Sore throat
- Anorexia
- Palatal petechiae
- Cervical lymphadenopathy
- Splenomegaly
- Mild hepatitis
Diagnosis: EBV Serology, FBC and LFTs
EBV IgM - Acute 4-6 weeks
EBV IgG - Lifelong (indicative of past infection)
