Infections of the Sensory System Flashcards
Identify the main sites of sensory infections.
- Eyes
- Oral cavity
- “Upper” respiratory tract
- Ears
- Sinuses
Identify the main ocular defense mechanisms.
- Eyelids
- Lacrimal system
- Conjunctiva
- Cornea
- Blood-ocular barrier
Identify examples of sensory system infections.
- Bacterial Conjunctivitis
- Adenovirus Infections
- VZV Infections
- Shingles
- HSV Infections
- Onchocerciasis
- Trachomatis
- AIDS (ocular manifestations)
Identify the main kinds of different bacterial conjunctivitis.
Common condition
Neonatal
HAI
Identify the main pathogens responsible for common bacterial conjuctivitis.
– Haemophilus influenzae
– Streptococcus pneumoniae – Moraxella spp.
Identify the main pathogens responsible for neonatal bacterial conjuctivitis.
– Neisseria gonorrhoeae
– Chlamydia trachomatis
– Escherichia coli
Identify the main pathogens responsible for hospital acquired bacterial conjuctivitis.
-Pseudomonas aeruginosa
Identify the main clinical features of bacterial conjunctivitis.
– Hyperaemic red conjunctivae
– Mucopurulent discharge
Identify the main investigations for bacterial conjunctivitis.
1) Samples: – Conjunctival swabs – Corneal scrapings 2) Lab diagnosis – Culture and NAAT
Describe treatment for bacterial conjunctivitis.
• Treatment with local antibiotics:
– Fusidic acid
– Tetracycline
– Chloramphenicol
ADENOVIRUS INFECTIONS
- Clinical features
- Treatment
- Serotypes
ADENOVIRUS INFECTIONS
- Clinical features: purulent + enlargement of ispilateral periauricular lymph node + may have corneal involvement (incl. punctate keratitis, subepithelial inflammatory infiltration)
- Treatment: Symptomatic treatment + avoid topical steroids
- Serotypes: 3, 4, 7, 8, and 10
VZV INFECTIONS
-Clinical features
VZV INFECTIONS (SHINGLES) -Clinical features: Ophtalmic dermatome of 5th cranial nerve Skin lesions Anterior uveitis Ocular perforation Retinal involvement Very painful (post-herpetic neuralgia)
Describe treatment of shingles.
- Antiviral treatment – aciclovir
- Severe inflammation – topical steroids
- Prevent primary infection – live attenuated vaccine
What proportion of shingles constitutes a chronic disease ?
25%
What is the most common infectious cause of blindness in the developed world ?
HSV infections
Identify the main clinical (ocular) features of HSV infections.
– Ulcerative blepharitis – Follicular conjunctivitis – Regional lymphadenopathy – Corneal involvement – not unusual (possible corneal oedema) – Opacity – Dendritic ulcer (marker of infection) – Keratitis – Opacity
Describe the timeline of HSV infections.
Relapses may occur ~4 years
Describe treatment for HSC infections.
- Antiviral treatment – aciclovir
- Avoid steroids
- Repeated scarring – corneal grafting
ONCHOCERCIASIS
- Disease caused
- Causative pathogen
- Transmission
- Clinical features
- Treatment
- Where in the world ?
ONCHOCERCIASIS
- Disease caused: River blindness
- Causative pathogen: Onchocerca volvulus
- Transmission: Blackfly
- Clinical features: Lesions may lead to blindness
- Treatment: Invermectin and doxycyline
- Where in the world ? West Africa, S America, C America
TRACHOMATIS
- Causative pathogen
- Other names
- Clinical features
- Treatment
- Where in the world ?
TRACHOMATIS
-Causative pathogen: Chlamydia trachomatis
-Other names: Chronic keratoconjunctivitis
-Treatment: Oral macrolides (azithromycin) + surgery for inturned eyelids
-Where in the world ? Largely confined to the tropics
-Clinical features:
Symptoms occur 3-10d post-infection:
Lacrimation
Mucopurulent discharge
Conjuntival involvement
Follicular hypertrophy
Identify preventive measures to eradicate trachomatis.
Surgery- inturned eyelids
Antibiotics (azithromycin)
Facial cleanliness to prevent disease transmission
Environmental change (to increase access to water and sanitation)
Identify ocular manifestations of AIDS.
- “Cotton wool spots” (“caused by damage to nerve fibers and are a result of accumulations of axoplasmic material within the nerve fiber layer”)
- Infarction of retinal nerve fibre layer
- CMV infection late in course of HIV disease (can eat the retina, and cause eue symptoms such as loss of vision)
Describe treatment of AIDS against its ocular manifestations.
- Antiviral treatment – IV ganciclovir
* Maintain therapy to prevent relapse
How does endophthalmitis.
• Develops after: – Ocular operation – Trauma – Inoculation of foreign body – Complication of systemic infection
Which class of pathogens cause endophthalmitis ?
Bacterial causes
How is endophthalmitis treated ?
Treated by systemic antibiotics and early vitrectomy
Identify conditions arising from poor mouth hygiene.
– Oral Candiasis (thrush)
– Caries
– Gingivititis
True or false: glycoproteins from biofilms are amazing at covering our teeth!
True
Describe normal microbiota of the RT.
• COMMON (>50% normal people)
- Bacteroides spp.
- Candida albicans
- Oral Streptococci
- Haemophilus influenzae
• OCCASIONAL (<10% normal people)
- Streptococcus pyogenes
- Streptococcus pneumoniae
- Neisseria meningitidis
• LATENT STATE IN TISSUES
- Herpes simplex virus type I (HSV)
- Epstein-Barr virus (EBV)
- Cytomegalovirus (CMV)
Identify examples of RT infections.
Rhinitis (sinusitis...) Pharyngitis Laryngitis Tracheitis Bronchitis Pnuemonia
Identify the main host defences of the RT.
- Saliva
- Mucus
- Cilia (muco-ciliary escalator/elevator)
- Nasal secretions
- Antimicrobial peptides
Identify the main infections of the RT, affecting the sensory system.
- Common Cold
- Acute Pharyngitis and Tonsillitis
- Cytomegalovirus (CMV)
- Epstein-Barr Virus (EBV): Glandular Fever
- Streptococcus pyogenes
- Parotitis
- Acute Epiglottitis
- Diphtheria
- Laryngitis and Tracheitis
- Otitis and Sinusitis
COMMON COLD
- Transmission
- Causative pathogens
- Pattern of infection
- Clinical features
- Prevention
COMMON COLD
-Transmission: aerosol, virus-contaminated hands
-Causative pathogens: Rhinoviruses, Coronaviruses
-Pattern of infection: Seasonal: early autumn and mid / late spring (but generally mild and self-limiting)
-Clinical features:
• tiredness
• slight pyrexia
• malaise
• sore nose and pharynx
• profuse, watery nasal discharge becoming mucopurulent
• sneezing in early stages
• secondary bacterial infection occurs in minority
-Prevention: No vaccine
Identify another term for common cold.
Acute coryza
Identify causative agents of acute pharyngitis and tonsillitis.
– Viruses
• Epstein-Barr virus (EBV)
• Cytomegalovirus (CMV)
– Bacteria
• Streptococcus pyogenes (tonsilitis is mainly this)
CMV (in acute pharyngitis and tonsilitis).
- Transmission
- Symptoms
- Treatment
CMV (in acute pharyngitis and tonsilitis).
- Transmission: Transmission in body secretions and organ transplants
- Symptoms: usually asymptomatic or mild in healthy adults
- Treatment: ganciclovir, foscarnet, cidofovir
What condition is the Epstein-Barr virus mainly responsible for ?
Infectious mononucleosis (Glandular fever)
What is the main histological effect of the EBV ?
Replicates B lymphocytes
Identify the clinical features of EBV.
– Fever – Headache – Malaise – Sore throat – Anorexia – Palatal petechiae – Cervical lymphadenopathy – Splenomegaly – Mild hepatitis - Swollen tonsils and uvula - Petechiae on the soft palate - White exudate
Describe treatment for glandular fever.
– Not to be treated with antibiotics (ampicillin and amoxycillin)!
– Contact sports or heavy lifting should be avoided durind the first month of illness and until any splenomegaly has resolved
Identify possible complications of glandular fever.
– Burkitt’s lymphoma
– Nasopharyngeal carcinoma – Guillain-Barré syndrome
Identify the main clinical features of Tonsilitis.
– Fever
– Pain in throat
– Enlargement of tonsils
– Tonsillar lymphadenopathy
Describe treatment of Tonsilitis.
- Susceptible to treatment with penicillin
* Increasing resistance to erythromycin and tetracycline
Identify possible complications to Strep Pyogenes infections.
Scarlet Fever – Caused by erythrogenic toxin from S. pyogenes • Peritonsillar abscess (“quinsy”) • Otitis media / sinusitis • Rheumatic heart disease • Glomerulonephritis
Which pathogen is responsible for Parotitis ?
Mumps virus
Identify the main clinical features of Mumps.
– Fever – Malaise – Headache – Anorexia – Trismus – Severe pain and swelling of parotid gland(s)
What are the primary sites of replications of the mumps virus in Parotitis ?
• Primary sites of replication: URT and eye
Describe treatment, and prevention for parotitis.
TREATMENT
– Mouth care
– Nutritional
– Analgesia
PREVENTION
– Active immunisation
– Measles-Mumps-Rubella (MMR) vaccine
Identify possible complications from parotitis.
– CNS involvement
– Epididymo-orchitis (~30% infected after puberty)
Identify the main causative pathogen of Acute epiglottitis.
Haemophilus influenzae (normal microbiota of nasopharynx)
Describe clinical features of acute epiglottitis.
– High fever
– Massive oedema of the epiglottis
– Severe airflow obstruction resulting in breathing difficulties
– Bacteraemia
Describe treatment and prevention of acute epiglottitis.
TREATMENT
– Life-threatening emergency
– Requires urgent endotracheal intubation
– Intravenous antibiotics (ceftriaxone or chloramphenicol)
PREVENTION
Hib vaccine
Describe diagnosis of acute epiglottitis.
– Do not examine throat or take throat swabs as this will precipitate complete obstruction of airway.
– Blood cultures to isolate H. influenzae
Identify the causative pathogen for Diphtheria.
Corynebacterium diphtheriae
Which parts of the body are colonised in diphteria ?
Colonises pharynx, larynx and nose (rarely skin and genital tract)
DIPHTERIA
- Transmission
- Clinical features
- Diagnosis
- Treatment
- Prevention
DIPHTERIA
• Transmission through aerosol
• Clinical features:
– Sore throat
– Fever
– Formation of pseudomembrane
– Lymphadenopathy
– Oedema of anterior cervical tissue (bull-neck)
• Diagnosis:
– Made on clinical grounds as therapy is usually urgently required
• 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 AND TRACHEITIS
- Causative pathogens
- Clinical features
LARYNGITIS AND TRACHEITIS
• Infections may spread down from the URT
• Causative pathogens: Usually viral in origin
– Parainfluenza virus
– Respiratory Syncytial virus – Influenza vurus
– Adenovirus
• Clinical features:
- In adults: hoarseness; retrosternal pain
- In children: dry cough; inspiratory stridor (croup)
Describe pathophysiology of otitis and 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
Identify the main causative agents for otitis and sinusitis.
• Main causative agents: – Respiratory syncytial virus (RSV) – Mumps virus – Streptococcus pneumoniae – Haemophilus influenzae – Bacteroides fragilis
OTITIS MEDIA
- Epidemiology
- Main pathogen
- Clinical features
- Complications
OTITIS MEDIA
-Epidemiology: most common in infants and small children
-Main pathogen: mainly Respiratory Syncytial Virus (RSV), but also S. pneumoniae and H. influenzae
-Clinical features:
Fever
Diarrhoea and vomiting
Bulging ear drum and dilated vessels
Fluid in middle ear (“glue ear”)
-Complications: May lead to chronic suppurative otitis media + May result in hearing difficulties and delayed learning development
OTITIS EXTERNA
- Main pathogens
- Treatment
OTITIS EXTERNA
- Main pathogens: Staph aureus, Candida albicans, Pseudomonas aeruginosa
- Treatment: antibiotic ear drops containing polymyxin
Does the middle ear have a similar microbiota to the skin ? the external ear ?
In contrast to the middle ear, the external ear has a similar microbiota to the skin
ACUTE SINUSITIS
- Clinical features
- Treatment
ACUTE SINUSITIS • Clinical features: – Facial pain – Localised tenderness • Treatment: – Ampicillin, amoxycillin, oral cephalosporins (especially to deal with β-lactamase-producing organisms)
