Infections of the Sensory System Flashcards
non specific ocular defences
eyelids tears ocular epithelium normal ocular bacterial flora mucin antibacterial factors macrophages and natural killer cells
specific ocular defences
eye-associated lymphoid tissue
langerhans cells - senitels (snitches)
t-lymphocytes
b-lymphocytes
where is the lacrimal gland
under the eyebrow
where are lysosomes found - they CLEAVE PETIDOGLYCANS this results in cell death
tears, saliva, mucous, they are also found int he granules of macrophages and neutrophils
lactoferrin
this binds to iron and starves the bacteria and fungi, it also breaks down RNA and DNA so has antiviral effects
- tears
- saliva
- mucous
- neutrophils
lysozyme and lactoferrin combined
they help to defeat gram negative bacteria
- lactoferrin alters the permeability of the lipopolysaccharide layer giving lysozyme access to the peptidoglycan layer
- thus is can cleave the petidoglycans and kill the cell
what are some natural bugs in the ocular biome
- staphylococcus
- streptococcus
- propionibacterium
- corynebacterium
what is the role of these naturally occurring bugs in the ocular biome
- they competitively inhibit growth of pathogenic organisms
this is why the prescription of antibiotics is so careful as it can effect your natural biome and harm your host defence
name three common eye infections
conjunctivitis - adult and neonatal
Keratitis - viral and bacterial
Orbital Cellulitis - pre and post-septal
name two rarer eye infections
- Endophthalmitis – Post-op and endogenous
* Retinochoroiditis – HIV/AIDS
Conjunctivitis
- Viral common
- Viral – adenovirus (rarer)
- Bacterial common
- Bacterial – trachoma
- Neonatal
sticky watery pink and inflamed eyes, this is usually self limiting and rarely causes any serious damage
adenovirus caused infections
- Bilateral,verysticky,red,painful
- Enlargement of ipsilateral periauricular lymph node
- Sore throat and cough - miserable
- May have corneal involvement - Punctate keratitis
- Symptomatic treatment – try to avoid topical steroids
- Keratitis can last a long time
Bacterial Conjunctivitis
- Discharge more yellow and thick
- Will not typically go away unless given Abx
Cause
• Haemophilus influenzae
• Streptococcus pneumoniae
• Moraxella
Treatment
• Chloramphenicol
• Fusidic Acid
keratitis
can be bacterial or viral:
bacterial = often in rich countries CL related
viral = HSV and HZO
Trachoma - main infectious cause of work wide blindness
conguncitis
inflammation
scarring
trichiasis (eyelashes grow wrong way) / entropion (eyelid sits incorrectly)
keratitis
can be bacterial or viral:
bacterial = often in rich countries CL related
viral = HSV (often in run down patients) and HZO
Trachoma - main infectious cause of work wide blindness
conguncitis
inflammation
scarring
trichiasis (eyelashes grow wrong way) / entropion (eyelid sits incorrectly)
what is the most frequent and the most pathogenic ocular pathogen which can cause corneal perforation in just 72 hours.
Pseudomonas aeruginosa
HSV Keratitis
• Often in ‘run down’ patients
• History of ‘cold sore’ on lips/nose in the past or recently
• Always unilateral – always same eye
• Painful, red, watery, photophobic
• Dendritic ulcer, can become geographic, new vessels, loss of sensation, scarring -
often recurrent
• Topical and oral aciclovir – often on oral low dose for months and years
what causes trachoma
chlamydia trachomatis
how do you treat river blindness
ivermectin treatment
what is a carrier of toxoplasma and what foes is cause
cats
oral pyrimethamine, sulfadiazine and corticosteroids
Endophthalmitis 1 in a 1000 risk
this is rare, but serious
develops after:
- intra-ocular operation e.g. cataract surgery
- trauma with inoculation of foreign body
- complication of systemic infection
treatment
- intraocular and systemic antibiotics +/- vitrectomy this is a surgical alternative
Otitis Media
most common in small children and infants mainly caused by RSV
- fever
- diarrhoea
- vomiting
- headache
- earache
may result in hearing difficulties and delayed learning development
Sinusitis
- Pathogen invasion of the air spaces associated with the URT
- Middle ear
- Outer ear
- Sinuses
- Blockage of the eustachian tube or sinuses
- Mucosal swelling prevents muco-ciliary clearance of infection
- Exacerbated by local accumulation of inflammatory bacterial products
treatment of sinusitis
ampicillin, amoxycillin oral cephalosporins (especially to deal with β-lactamase- producing organisms)
what is the main cause of the common cold
rhinoviruses and its SEASONAL
Acute Pharyngitis & Tonsillitis
virus causes mostly caused by the EBV and CMV
bacterial causes
• Streptococcus pyogenes
Cytomegalovirus (CMV)
- Transmission in body secretions and organ transplants
- Usually asymptomatic or mild in healthy adults
- Virus can reactivate and cause disease when cell- mediated immunity is compromised
- Treatment with ganciclovir, foscarnet, cidofovir
Epstein-Barr Virus (EBV): Glandular Fever
• Replicates in B lymphocytes
- swollen tonsils and uvula
- petechiae on the soft palate
- white exudate
DO NOT TREAT WITH ANTIBIOTCS
- Clinical features:
- Fever
- Headache
- Malaise
- Sore throat
- Anorexia
- Palatal petechiae
complications of glandular fever
- Burkitt’s lymphoma
- Nasopharyngeal carcinoma
- Guillain-Barré syndrome
Tonsillitis
- Caused by Streptococcus pyogenes
- Clinical features:
- Fever
- Pain in throat
- Enlargement of tonsils
- Tonsillar lymphadenopathy
- Susceptible to treatment with penicillin
- Increasing resistance to erythromycin and tetracycline
tonsillitis complications
- Scarlet Fever
- Caused by erythrogenic toxin from S. pyogenes
- Peritonsillar abscess (“quinsy”)
- Otitis media / sinusitis
- Rheumatic heart disease
- Glomerulonephritis
Parotitis also known as mumps
- Caused by the mumps virus
- Clinical features:
- Fever
- Malaise
- Headache
- Anorexia
- Trismus
- Severe pain and swelling of parotid gland(s)
- Primary sites of replication: URT & eye
mumps treatment, prevention and complications
treatment:
- mouth care
- nutritional
- analgesia
prevention:
- acute immunisation
- MMR
complications:
- CNS involvement
- Epididymo-orchitis
Acute Epiglottitis
Diagnosis:
• Do not examine throat or take throat swabs as this will
precipitate complete obstruction of airway.
• Blood cultures to isolate H. influenzae
• Treatment:
• Life-threatening emergency
• Requires urgent endotracheal intubation
• Intravenous antibiotics (ceftriaxone or chloramphenicol)
Diphtheria
- Transmission through aerosol
- Clinical features:
- Sore throat
- Fever
- Formation of pseudomembrane
- Lymphadenopathy
- Oedema of anterior cervical tissue (bull- neck)
diphtheria management
- Treatment:
- Prompt anti-toxin therapy administered intramuscularly • Concurrent antibiotics (penicillin or erythromycin)
- Strict isolation
- Prevention:
- Childhood immunisation with toxoid vaccine
- Booster doses given if travelling to endemic areas if >10 years have elapsed since primary vaccination
Laryngitis & Tracheitis
- Infections may spread down from the URT
- Usually viral in origin
- Parainfluenza virus
- Respiratory Syncytial virus • Influenza vurus
- Adenovirus
- In adults: hoarseness; retrosternal pain
- In children: dry cough; inspiratory stridor (croup)
