S1 Clinical Presentation & Etiology of URTIs Flashcards
What does Most common URTIs involve ? (7)
Nose (rhinitis or common cold)
Pharynx (pharyngitis, sore throat, tonsillitis)
Ear (otitis media, otitis externa)
Sinuses (sinusitis)
Epiglottis (epiglottitis)—
Why URTIs are most common site of infections in human ?
URT most common site exposed constantly to potential pathogens from environment during breathing and from hands
What is the most common causes of URTIs ?
Viruses
What are the normal bacteria ( oral flora of the mouth ) ? What is the pathogens that can be carried asymptomatic ?
NORMAL FLORA :
- Streptococcus viridins
- Diphtheroids
- Anaerobic cocci
PATHOGENS CARRIED ASYMPTOTIC:
- Streptococcus pyogens ( most )
- Streptococcus pneumonia
- Hemophlus influenza
- Cornybactrium diphtheria (least )
What are the mechanisms to protect URT from infections ? (6)
Mechanical defenses ( These includes: cough, gag and sneeze reflex )
Viscous mucous secretions which entrap particulate materials
Ciliated epithelium in the nose and sinuses
Lysozyme in saliva
Lymphoid tissue, secretory immunoglobulin IgA
Rich vasculature that can rapidly deliver phagocytic lymphocyte
When does Bacterial URTIs usually occur ?
After insult to the mechanical defenses due to :
- allergic rhinitis
- irritation
- viral infections
As they impair the ciliary function and produce mucosal edema that block the draining channels of the sinuses and middle ear
What are the etiological causes of pharyngitis?
- Viruses ( more than 70%)
2. Bacteria
What are the viruses that cause pharyngitis?
- Influenza A,B,C
- parainfluenza
- Rhinitis
- Adenovirus
- Coronavirus
- ebstain-bar virus
- HSV
- CMV
What are the bacteria that causes pharyngitis ?
- Group A streptococci ( streptococcus pyogenes ) most common type
- Group C and D
- Cornybacterium diphtheria
- N. Gnoreah
- Vincet angina
How you can differentiate between viral and bacterial pharyngitis?
- VIRAL
- Mild pharyngeal symptoms
- rhinorrhea - BACTERIAL or EBV
- High fever
- tonsillar exudates
- cervical lymphadenopathy
- absence of cough
What are the features of streptococcus pyogenes ?
- Group A streptococci
- Beta hemolytic
- Agglutinate to anti-body A
- Sensitive to bacitracin
How S.pyogens are treated ? Why ?
Start with penicillin
If allergic use erythromycin
Aim of treatment is to prevent complications ?
- Acute rheumatic fever
- Acute glomerulonephritis
What are the systems that are affected by C. Diphtheria complications ?
- Central nervous system ( polyneuritis )
2. Cardiac system ( myocarditis)
What are the Clinical feature of diphtheria ?
- Fever
- pharyngitis
- Enlarged cervical lymph nodes
- Pseudomemebrane that may cause airway obstruction
- Myocarditis with cardiac failure
- polyneuritis
What are the features of C. Diphtheria ?
- Gram positive bacilli
2. Produce exotoxins ( detected by PCR )
How you can treat C. Diphtheria?
- Isolation of suspected cases
- Antibiotics should be started before confirmation (erythromycin)
- Antitoxin
- Prophylaxis for contacts (erythromycin)
What is otitis media ? And What are the main clinical features ?
- inflammation and formation of pus and its accumulation behind ear-drum Clinical features : * fever * ear ache * irritability and refuse to eat
What are the etiological causes of otitis media ?
VIRAL ( more than 50% )
- influenza
- rhinovirus
- RSV
- enterovirus
BACTERIA ( SSS+ MM+ H)
- streptococcus pneumonia
- streptococcus pyogenes
- staphylococcus aureus
- morexella cataralis
- mycoplasma pneumonia
- hemophilus influenza
What is the management of otitis media ?
Antimicrobial agents to cover common bacterial pathogens
Amoxicillin
Amoxicillin & clavulanic acid
Cephalosporin
Symptomatic treatment:
Decongestants & antihistamines to reduce
congestion of the respiratory mucosa and relieve obstruction of the Eustachian tube
What is the cause of Chronic otitis media ?
- Caused mainly by bacterial pathogens
- Range of causative agents is wider than AOM including many Gram-negative bacteria
What is the prevention of the recurrent infections of otitis media ?
Chemoprophylaxis (once daily amoxicillin)
Immunoprophylaxis ( pneumococcal vaccine)
Surgery ( myringotomy= incision of the ear drum )
What are the main types of otitis externa ? What is their etiologies ?
- Acute
- localized ( pustules or fruncles ) due to staph. Aureus
- diffuse ( swimmer ear ) due to pseudomonas aurignosa - Chronic
- Drainage problem in patients with suppurative otitis media - Malignant
- Mainly P. aeruginosa
How sinusitis is normally caused ?
Mainly occur as a result of bacterial complications following viral infection
What are the main complications of sinusitis?
It affects CNS mainly, leading to
- meningitis
- brain abscess
