Microbiology Flashcards
Herpes Simplex Virus: Structure
Enveloped double stranded DNA alpha herpes virus
Herpes Simplex Virus: Two type
HSV-1
HSV-2
Herpes Simplex Virus: HSV-1 associated with what?
Orofacial disease
Herpes Simplex Virus: HSV-2 associated with what?
Genital disease
Herpes Simplex Virus: HSV-1 - Acquired when?
In childhood
Herpes Simplex Virus: HSV-1 - Causes what?
Oral lesions
Herpes Simplex Virus: HSV-1 - Transmission
Infected oral secretions during close contact
Oral-genital or Genital-Genital
Contamination of skin abrasions with infected oral secretions
Herpes Simplex Virus: HSV-1 - Can cause what oral disease?
Primary Gingivostomatitis
Herpes Simplex Virus: Primary Gingivostomatitis - Most common in what population group?
Pre-school children
Herpes Simplex Virus: Primary Gingivostomatitis - Impacts what regions? (3)
Lips
Buccal mucosa
Hard palate
Herpes Simplex Virus: Primary Gingivostomatitis - Presentation
Vesicles and Ulcers present
Herpes Simplex Virus: Primary Gingivostomatitis - Clinical Presentation of Primary Infection
2-12 days for clinical illness - multiple painful oral lesions with local lymphadenopathy
Herpes Simplex Virus: Primary Gingivostomatitis - Systemic Clinical Presentation
Fever
Malaise
Headache
Herpes Simplex Virus: Primary Gingivostomatitis - Length of presentation without therapy
12 days
Herpes Simplex Virus: Primary Gingivostomatitis - Management
Aciclovir
Herpes Simplex Virus: Inactive form remains where?
Sensory nerve cells
Herpes Simplex Virus: Can reactivate to do what?
Reinfect mucosal surfaces
Herpes Simplex Virus: Viral replication occurs where?
Epidermis
Dermis
Herpes Simplex Virus: Can infect what structures?
Sensory and autonomic nerve endings - CN V - Mandibular, Maxillary and Ophthalmic Branches and the Meningeal branch and the Trigeminal ganglion
Herpes Simplex Virus: Virus travels from nerve endings to where?
Sensory ganglia - establishes a latent reservoir that cannot be eliminated by the immune system
Herpes Simplex Virus: Virus persists in a latent state where?
Trigeminal ganglia to reactivate intermittently
Herpes Simplex Virus: Virus attaches to epithelial cells through what?
HSV-1 surface glycoproteins and cellular HSV receptors e.g. Nectin-1
Herpes Simplex Virus: How is it transported into sensory ganglia?
Retrograde transport
Herpes Simplex Virus: HSV-1 establishes life-long latent infection where?
Trigeminal or sacral ganglia
Herpes Simplex Virus: Latency is characterised by what?
Restricted transcriptional profile with the latency-associated transcripts
Herpes Simplex Virus: Transported to epithelial cells from ganglia how?
Anterograde Axonal Transport
Herpes Simplex Virus: Cold Sores - Pathophysiology
Reactivation of HSV-1 from nerves causes active infection
Herpes Simplex Virus: Cold Sores - Management
Aciclovir
Herpes Simplex Virus: Cold Sores - Aciclovir does not prevent what?
Latency
Herpes Simplex Virus: Precipitating factors for HSV-1 (4)
Immunodeficiency
Stress
Exposure to sunlight
Fever
Herpes Simplex Virus: Cold Sores - Oral herpetic lesions are often caused by what?
HSV-1
Herpes Simplex Virus: Cold Sores - What would suggest HSV is not the causative organism?
Recurrent intra-oral lesions
Herpes Simplex Virus: Cold Sores - What precedes the appearance of painful lesions?
Prodomal symptoms 24 hours before - Pain, Burning, Tingling and Pruritus 6-53 hours before the appearance of the first vesicles
Herpes Simplex Virus: Cold Sores - Recurrences typically present where?
Vermillon border
Herpetic Whitlow: Often misdiagnosed as what?
Bacterial infection
Herpetic Whitlow: Occupational hazard of what?
Dentistry and anaesthetics
Herpetic Whitlow
HSV infection of the finger due to innoculation of the virus through a break in the skin
Herpetic Whitlow: Time period if left untreated
2-3 weeks
Herpes Simplex Virus: Herpes Simplex Encephalitis - Clinical Presentation (5)
Rapid onset of:
- Fever
- Headache
- Seizures
- Focal neurological signs
- Impaired consciousness
Herpes Simplex Virus: Diagnosis - Procedure used
Swab of lesion in the viral transport medium and detection via PCR
Herpes Simplex Virus: Diagnosis - What is the diagnostic cell?
Multinucleated giant cell - epithelial cell containing numerous nuclei with nuclear moulding and viral inclusions (causes a glass appearance)
Herpes Simplex Virus: Diagnosis - Tzanck Smear
Smear material from the base of a vesicle onto a slide and stain it with Wright’s stain - positive smear demonstrates multi-nucleate cells
Limited utility due to poor sensitivity and specificity
Herpangina
Benign clinical syndrome characterised by fever and painful papulo-vesiculo-ulcerative oral enanthem
Herpangina: Causative organism
Coxsackie viruses - most commonly A serotypes
Herpangina: Clinical Presentation
Abrupt fever with hyperaemia and yellow/grey-white papulovesicular papules that undergo vesiculation in 24 hours
Herpangina: Diagnostic test
Clinical or PCR test of the swab in viral transport medium
Hand, Foot and Mouth Disease
Clinical syndrome characterised by oral enanthem and macular/maculopapular/vesicular rash of the hands and feet
Hand, Foot and Mouth Disease: Causative organism
Coxsackie Virus - A serotypes common
Hand, Foot and Mouth Disease: Diagnosis
Clinical or by PCR test of the swab in a viral transport medium
Primary Syphilis: Causative Organism
Treponema pallidum
Primary Syphilis: Clinical presentation
Painless indurated ulcer on the genitals, mouth or pharynx
Apthous Ulcers
Recurring painful ulcers of the mouth that are round or ovoid and have inflammatory halos
Apthous Ulcers: Confined to what area?
Mouth
Apthous Ulcers: Duration
Each ulcer lasts 3 weeks
Apthous Ulcers: Most common cause of mouth ulcers
Recurrent apthous stomatitis - canker sores
Apthous Ulcers: Risk Factors (5)
Genetic predisposition
Trauma
Stress
Smoking cessation
Hormonal imbalance
Apthous Ulcers: Ulcers of Systemic Disease - Behcets Disease (3)
Recurrent oral ulcers
Genital ulcers
Uveitis
Sore throat clinical presentation
Pain at the back of the throat
Acute pharyngitis
Inflammation of the oropharynx behind the soft palate
Tonsillitis
Inflammation of the tonsils
If a sore throat and lethargy persist for 2 weeks what should be suspected?
Mononucleosis
Sore Throat: Centor Score
Gives one point for:
- Tonsillar exudate
- Tender anterior cervical lymph nodes
- History of fever
- Absence of cough
Bacterial Sore Throat: Most common cause
Streptococcus pyogenes
Bacterial Sore Throat: Management
Penicillin
Bacterial Sore Throat: Streptococcus Pyogenes - Late Complications (2)
Rheumatic Fever - 3 weeks post-sore throat
with fever, arthritis and pancarditis
Glomerulonephritis - 1-3 weeks post-sore throat with haemturia, albuminuria and oedema
Bacterial Sore Throat: Group A Beta Haemolytic Streptococcus - How is this assessed?
CENTOR Score
Bacterial Sore Throat: Group A Beta Haemolytic Streptococcus - Management for FeverPAIN 0/1OR Centor 0/1/2
Do not offer an antibiotic
Bacterial Sore Throat: Group A Beta Haemolytic Streptococcus - Management for FeverPAIN 2/3
Consider no antibiotic or an antibiotic backup prescription - use if no improvement within 3-5 days
Bacterial Sore Throat: Group A Beta Haemolytic Streptococcus - Management for FeverPAIN 4/5 OR Centor Score of 3/4
Immediate antibiotic required
DMARD
Disease-Modifying Anti-Rheumatic Drugs
DMARDs and Sore Throat: Management
FBC
Withhold the DMARD whilst awaiting the result
DMARDs and Sore Throat: Management if person has leucopenia or deteriorates
Provide symptomatic relief and antibiotics
Tonsillitis: Management - Unable to swallow
Benzylpenicillin IV
Tonsillitis: Management - Unable to swallow with a penicillin allergy
Clarithromycin IV
Tonsillitis: Management - Able to swallow
Penicillin for 5 days
Tonsillitis: Management - Able to swallow with a penicillin allergy
Clarithromycin
Diphtheria
Infectious disease caused by gram positive bacillus Corynebacterium diphtheriae
Diphtheria: Hallmark
Tough pharyngeal membrane
Diphtheria: Respiratory types is typically called by what?
Toxin-producing strains of C. diphtheriae
Diphtheria: Length of time
Symptoms begin 2-5 days after infection
Diphtheria: Can cause what to happen to the heart?
Myocarditis due to toxin damage
Diphtheria: Most common presentation (4)
Sore throat
Malaise
Cervical lymphadenopathy
Low grade fever
Diphtheria: Earliest pharyngeal finding
Mild erythema that can progress to gray and white exudate
Diphtheria: In untreated patients when is the infectious period?
Begins at symptom onset and lasts two weeks
Diphtheria: In treated patients what is the time frame?
Infectious period lasts less than four days
Diphtheria: Neurological Toxicity - Local Neuropathies (2)
Paralysis of the soft palate
Paralysis of the pharyngeal wall
Diphtheria: Neurological Toxicity - Cranial Neuropathies (4)
Oculomotor and Ciliary > Facial or Laryngeal paralysis
Diphtheria: Neurological Toxicity - What may present on the posterior pharynx?
Pseudomembrane - may obstruct the airway
Diphtheria: The exotoxin is toxic to what two structures?
Heart
Nervous System
Diphtheria: Management
Anti-toxin
Penicillin or Erythromycin
Diphtheria: Vaccine type
Cell-free purified toxin from C. diphtheriae (toxoid vaccine)
Infectious Mononucleosis: Clinical Presentation (6)
Fever
Enlarged lymph noes
Sore throat
Pharyngitis
Tonsillitis
Malaise and Lethargy
Infectious Mononucleosis: Haematological signs
Leucocytosis
Atypical lymphocytes on film
Infectious Mononucleosis: Causative organism
Epstein-Barr Virus
Infectious Mononucleosis: Establishes a persistent infection where?
In the epithelial cells - mainly of the pharynx
Infectious Mononucleosis: Two Phases of Primary Infection
Primary infection in early childhood rarely results in infectious mononucleosis
Primary infection in those >10 years old results in infectious mononucleosis
Infectious Mononucleosis: Why does it establish a life long infection?
Establishes latency with periodic reactivation with oral shedding of EBV
Infectious Mononucleosis: When are corticosteroids considered?
Upper Respiratory Tract Obstruction
Haemolytic Anaemia
Oral Thrush: Causative organism
Candida albicans
Oral Thrush: Clinical presentation
White patches on red and raw mucous membranes of the throat and mouth
Oral Thrush: Aetiologies (4)
Post-antibiotic therapy
Immunosuppression
Smoking
Inhaled steroids
Oral Thrush: Management options (2)
Nystatin
Fluconazole
Acute Otitis Media: Management - First line (+ if penicillin allergy)
Amoxicillin (Clarithromycin)
Recurrent Otitis Media: Definition
> 3 episodes in 6 months or >5 episodes in 12 months
Recurrent Otitis Media: Management - What is considered in paediatric cases?
Amoxicillin
Otitis Externa: Bacterial Causes (3)
Staphylococcus aureus
Proteus species
Pseudomonas aeruginosa
Otitis Externa: Fungal Causes (2)
Aspergillus niger
Candida albicans
Otitis Externa: Management - Swabs and antibiotics reserved for what?
Unresponsive or severe cases
Otitis Externa: Management - Mild cases
Acetic Acid for 7 days - increase management if no improvement after 3 days
Otitis Externa: Management - Moderate cases
Otomize or Sofradex
Otitis Externa: Management - Antibiotic options (2)
Gentamicin
Ciprofloxacin (with Dexamethasone)
Otitis Externa: Management - For fungal infection
Clotrimazole solution
Otitis Externa: Management - Oral or IV antibiotics considered when?
If there is cellulitis or disease extends out of the ear canal
Malignant Otitis
Extension of otitis externa into the bone surrounding the ear canal - the mastoid and temporal bones
Malignant Otitis: Clinical Presentation
Pain and headache
Malignant Otitis: Signs (3)
Granulation tissue at the bone-cartilage junction of the ear canal
Exposed bone in the ear canal
Facial nerve palsy
Acute Sinusitis: 1st line management in severe cases
Phenoxymethylpenicillin
Acute Sinusitis: 2nd line management in severe cases
Doxycycline
Acute Sinusitis: When can doxycycline not be used?
In children