Infections of the sensory System Flashcards
What are / name the basic ocular defense mechanisms
- Eyelids
- Lacrimal system
- Conjunctiva
- Cornea
- Blood-ocular barrier
What are the common bacteria responsible for bacterial conjunctivitis?
- Haemophilus influenzae
- Streptococcus pneumoniae
- Moraxella spp
What are some of the bacteria which can cause conjunctivitis in a neonate?
- Neisseria gonorrhoeae
- Escherichia coli
- Staphylococcus aureus
- Haemophilus influenza
- Chlamydia trachomatis
Also herpes simplex
Name a hospital aquired infection which can cause bacterial conjunctivitis?
Pseudomonas aeruginosa
WHat are the clinical features of bacterial conjunctivitis?
- Hyperaemic red conjunctivae
- Mucopurulent discharge
How can samples be taken for conjunctivitis?
- Conjunctival swabs
- Corneal scrapings
Lab diagnosis can be made through a culture or NAAT
What local antibiotics can be used to treat bacterial conjunctivitis?
- Fusidic acid
- Tetracycline
- Chloromphenicol (most common)
What clinical features of conjunctivitis can differentiate bacterial from viral conjunctivitis?
- Thick discharge = bacterial
- More watery = viral
What serotypes of adenovirus can cause conjunctivitis?
3, 4, 7, 8 and 10
What are some clinical features of conjunctivitis caused by adenovirus?
- Purulent
- Enlargement of ipsilateral periauricular lymph node
- May have corneal involvement (punctate keratitis, subepithelial inflammatory infiltration)
How should an adenovirus infection (conjunctivitis) be treated?
- Symptommatic treatment
- Pain relief
- Avoid use of topical steroids - may reduce immune response
What are the clinical features of a Varicella Zoster Virus infection of the eye (shingles)?
- Affects opthalmic dermatome of 5th cranial nerve
- Very painful (post-hepetic neuralgia)
- Skin lesions
- Anterior uveitis
- Ocular perforation
- Retinal involvement
What is VZV treated with?
Antivirals - aciclovir
- Possibly topical steroids in severe inflammation
Shingles is a chronic disease in what percentage of people?
25%
How is shingles prevented?
Through a live attenuated vaccine
What is the most common infectious cause of blindness in the developed world?
Herpes simplex Virus
What are the clinical features of HSV infection?
- Dendritic shaped ulcer on surface of the eye
- Unilateral almost always
- Ulcerative blepharitis
- Follicular conjunctivitis
- Regional lymphadenopathy
- Corneal involvement
What can HSV cause in the eye permenantly?
Corneal scarring
What is HSV treated with?
Aciclovir, avoid use of steroids
What parasite causes onchocerciasis (river blindness)?
Onchocera volvulus (transmitted via blackfly)
How is onchocera volulus (river blindness) treated?
- Ivermectin and doxycycline
- Mass treatment of whole populations, insecticides for blackfly
How can chlamydia trachomatis cause blindness?
- Chronic inflammation and scarring within eyelid causing it to turn in on eyeball
- Eyelashes then rub against eyeball causing corneal scarring
- Secondary infection can follow
What is used to treat chlamydia trachomatis?
Oral macrolides
- Azithromycin
What symptoms occur in chlamydia trachomatis?
- 3-10 days post infection
- Lacrimation
- Mucoprulent discharge
- Conjunctival involvement
- Folicular hypertrophy
What is the SAFE camapign?
Aims to eradicate trachomatis
- S: Surgery for inturned eyeballs
- A: Antibiotics
- F: Facial cleanliness
- E: Environmental change - increase access to water and sanitation
What clinical sign is seen in AIDS in the eyes?
- “Cotton wool spos”
- Infraction of retinal nerve fibre layer
What infection is responsible for the “cotton wool spots”?
Cytomegalovirus (as a result from AIDS)
What is CMV in the eye treated with?
IV ganciclovir
- Maintain therapy to prevent relapse
What is endopthalmitis?
Infection within eyeball itself
What does endopthalmitis develop after?
- Occular operation
- Trauma
- Inoculation of foreign body
- Complication of systemic infection
What is endopthalmitis treated with?
Bacterial causes treated by systemic antibiotics and early vitrectomy
What is dental caries?
- Tooth decay
- Damage to a tooth that can happen when decay-causing bacteria in your mouth make acids that attack the tooth’s surface
What are the host defences of the respiratory tract?
- Saliva
- Mucus
- Cilia (muco-ciliary escalator/elevator)
- Nasal secretions
- Antimicrobial peptides
What are the common causative agents of the common cold?
- Rhinoviruses (40%) (>100 serotypes)
- Coronaviruses (30%) (>3 serotypes)
- Coxsackie virus A
- Echovirus
- Parainfluenza virus
What are the common viral causative agents responsible for acute pharyngitis and tonsilitis?
- Epstein-Barr Virus (EBV)
- Cytomegalovirus (CMV)
- Herpes simplex virus type I
- Rhinovirus
- Coronavirus
- Adenovirus
What are the common bacterial causitive agents responsible for acute pharyngitis and tonsilitis?
- Streptococcus pyogenes
- Haemophilus influenzae
- Corynebacterium diptheriae
What cells do EBVs replicate in?
B lymphocytes
What are the clinical features of EBV?
- Swollen tonsills and uvula
- Petechiae on the soft palate
- White exudate
- Fever
- Headache
- Malaise
- Sore throat
- Anorexia
- Palatal petechiae
- Cervical lymphadenopathy
- Spelnomegaly
- Mild hepatitis
What can happen if glandular fever is treated with amoxicillin or ampicillin?
Painful rash can develop (therefore they are to be AVOIDED)
What are some of the complications of glandular fever?
- Burkitt’s lymphoma (with malaria) (B cell lymphoma)
- Nasopharyngeal carcinoma
- Guillain-Barre syndrome
What should be avoided after glandular fever?
Contact sports or heavy lifting should be avoided during forst month of illness and until any splenomegaly has resolved
What is are the clinical features of strep pyogenes tonsilitis?
- Fever
- Pain in throat
- Enlargement of tonsils
- Tonsilar lymphadenopathy
What is strep pyogenes tonsilitis treated with?
Penicillin (increasing resistance to erythromycin and tetracycline)
What is a complication of strep pyogenes infection?
- Scarlet fever (erythrogenic txin from the bacteria)
- Peritonsillar abscess (quinsy)
- Ottis media / sinusitis
- Rheumatic heart disease
- Glomerulonephritis
What is parotits caused by?
Mumps
What are the primary sites of replication of mumps?
URT and eye
What are the complications of mumps?
- CNS involvement
- Epidymo-orchitis (~30% infected after puberty)
What is Acute epiglottitis caused by?
Haemophilus influenza
What percentage of healthy people have H influenza present in nasopharynx?
75%
How can acute epiglottitis be prevented?
Hib vaccine (88% reduction in england and wales since 1992)
What are the clinical features of acute epiglottitis?
- High fever
- Massive oedema of the epiglottis
- Severe airflow obstruction resulting in breathing difficulties
- Bacteraemia
How is acute epiglottitis diagnosed?
- Blood cultures to isolate H. influenzae
- DO NOT examine throat or take throat swabs as this willl precipitaate complete obstruction of airway
How is acute epiglottitis treated?
- Life-threatening emergency
- Requires urgent endotracheal intubation
- IV Ceftriaxone or chloramphenicol
What bug causes diptheria?
Corynebacterium diptheriae
WHat are the clinical features of diptheria?
Childhood disease (usually) Oedema of anterior cervical tissue (bull-neck) - Sore throat - Fever - Formation of pseudomembrane - Lymphadenopathy
What is diptheria treated with?
- Prompt anti-toxin therapy administered IM
- Concurrent antibiotics (penicillin or erythromycin)
- Strict isolation
What are common causes of laryngitis and tracheitis?
- Parainfluenza virus
- Respiratory Syncytial virus
- Influenza
- Adenovirus
Usually viral - spread down from URT
What are the symptoms of laryngitis and tracheitis?
- Adults: hoarsness; retrosternal pain
- Children; Dry cough; inspiratory stridor (croup)
What are some of the complicaions of otitis and sinusitis?
- Blockage of eustachian tube or sinuses
- Mucosal swelling prevents muco-ciliary clearence of infection
- Exacerbated by local accumulation of inflammatory products
Wat are the main causitive agents of ottitis and sinusitis?
- Respiratory syncytial virus (RSV)
- Mumps virus
- Streptococcus pneumoniae
- Haemophilus influenzae
- Baceteroides fragilis
When is otitis media most common?
Infants and small children
What are the most common bugs responsible for otitis media?
50% viral in origin - mainly RSV
Also S. pneumoniae and H influenzae
Thick discharge linked to bacterial infection
What are the clinical features of otitis media?
- Fever
- Diarrhoea and vomitting
- Buldging ear drum and dilated vesels
- Fluid in middle ear (glue ear)
What are some complications of Otitis media?
- May lead to chronic suppurative otitis media
- May result in hearing difficulties and delayed learning development
What are common infectious agents in otitis externa?
Similar microbiota to skin
- Staphylococcus aureus
- Candida albicans
- Pseudomonas aeruginosa
What is otitis externa treated with?
Antibiotic ear drops containing polymyxin
