Respiratory Tract Infections 3 Flashcards
Mumps is caused by which viral family
Paramyxoviridae family
Mumps: Biology & Epidemiology
• Paramyxoviridae family • Enveloped ss(-)RNA virion • 2 glycoproteins • HN – mediates hemagglutination and neuraminidase activity • F – fusion to the host cell • One serotype, endemic worldwide
Mumps transmission
Aerosol transmission
- Infections are often asymptomatic/subclinical
- Outbreaks are associated with crowded conditions (colleges, community gatherings, etc…)
- Rising number of cases in recent years
Mumps Pathogenesis
Mumps Parotitis clinical presentation
- Low grade fever, malaise, myalgia, headache and anorexia
- Parotitis may be unilateral or bilateral
- Swelling of the parotid and tenderness
- Earache
- difficulty eating, swallowing, talking
Mumps complications
- Orchitis – most common complication after parotitis • Sterility is rare but subfertility may occur
- Oophoritis
- Meningoencephalitis• Usually self-limited
- Rare: Loss of hearing, Pancreatitis & Thyroiditis
- Most patients experience complete recovery with no long term effects
Prevention of mumps
MMR/MMRV Vaccine
• Vaccine is ~88% protective with 2 doses
How does bacterial pharyngitis present
• Acute onset
• Sore throat, fever
• Nausea, vomiting and headache often present
• Erythematous posterior pharynx and palatine
tonsils
• Tender cervical lymphadenopathy
• While or yellow exudate in tonsillar crypts
How does viral pharyngitis present
- Gradual onset
- Low-grade fever
- Less erythema and swelling of the pharynx
- Discrete ulcerative lesions
- Tonsils generally not involved
- conjunctivitis, coryza, cough may be present
Bacterial causes of pharyngitis
Strep pyogenes
Fusobacterium necrophorum
Strep dysgalactiae
Viral causes of pharyngitis
Rhinovirus
Coronavirus
Adenovirus
S. pyogenes: Biology
Most common cause of pharyngitis
• Gram positive cocci (in chains; discoid colonies)
• β-hemolytic
• Lancefield Group A
• Important for Rapid Strep test
• PYR positive
• detection of pyrolidonyl arylamidase (hydrolysis of L-pyrrolidonyl-β-naphthylamide)
• Bacitratin sensitive
*GABHS - Group A β-hemolytic streptococcus
Clinical Presentation: Pharyngitis
- Develops ~2-4 days after exposure
- Abrupt onset of fever, sore throat, malaise, headache, dysphagia
- Erythematous posterior pharynx and palatine tonsils
- Tender cervical lymphadenopathy
- Palatal petechiae
- Tonsils may have white or yellow exudate
Clinical Presentation: Scarlet Fever
- Fever, headache, sore throat, nausea, vomiting and malaise
- Diffuse, sandpaper-like rash develops, initially on trunk and groin then spreads to face
- Accentuation of the rash in flexor creases (i.e., under the arm, in the groin), termed “Pastia’s lines
Which infection presents with strawberry tongue
Scarlet fever!
- Initially a thick, white coat and swollen papillae seen on tongue (white strawberry tongue)
- White coating desquamates leading to red strawberry tongue appearance
Explain the polymicrobial infection seen in Chronic Tonsillitis & Peritonsillar Abscess
Polymicrobial Infection • Group A Strep (GABHS) 1st colonizer • Staph aureus (MRSA) 2nd colonizer • Gram-Negative Anaerobic Rods (GNAR) 3rd colonizer • Bacteroides is representative species
Endogenous flora Staph aureus establish biofilm and anaerobes GNAR establish abscess in necrotic tissue.
How to manage Chronic Tonsillitis & Peritonsillar Abscess
Management involves broad-spectrum antibiotics, drainage and potentially surgery.
Clinical Presentation: Peritonsillar Abscess
- Fever
- Dysphagia
- Severe throat pain , drooling to avoid swallowing saliva
- “Hot potato”/muffled voice
- Trismus
What complication can pharyngitis lead to
Acute rheumatic fever
• Multisystem disease resulting from an autoimmune reaction to untreated or unresolved infection with GABHS. Typically develops ~3 weeks after infection
Which disease is this
Acute rheumatic fever
What type of sensitivity is seen in rheumatic fever
Type II Hypersensitivity reaction
Explain the molecular mimicry seen in acute rheumatic fever
• Immune response targeted at streptococcal
antigens also recognizes human tissues
• Cross-reactive antibodies bind to endothelial cells of heart valve
• Leads to recruitment/activation of lymphocytes and lysis of endothelial cells
Clinical Presentation: Acute Rheumatic Fever
- Fever (usually low-grade)
- Polyarthralgia
- Carditis
- Murmur, irregular heart beat, CHF
- Polyarthritis
- Erythema marginatum
- Subcutaneous nodules
- Sydenham’s chorea
How to diagnose acute rheumatic fever
Evidence of preceding GABHS infection • Positive throat culture • Rapid antigen test • Recent scarlet fever • Elevated or rising ASO titer, antiDNAse B, or other streptococcal antibody titer
Jones Criteria
