Upper Respiratory Tract Infections

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Upper Respiratory Tract Infections
Clinical correlations 4 Med Micro 2008

• Divya Ahuja, M.D.
• November 2008

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Burden of URI

• Significant morbidity and direct health care
  costs
• Direct costs of 17 billion annually
• Occasionally leads to fatal illness
• Excessive use of antibiotics a major issue

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The Common Cold

• Children average 8 per year, adults 3
• Parainfluenza isolated in 1955
• Rhinoviruses 30 to 35 coronaviruses about 10,
  miscellaneous known viruses about 20, presumed
  undiscovered viruses up to 35, group A
  streptococci 5 to 10
• Seasonal variation
• Rhinovirus early fall
• Coronavirus- winter
• Day cares are culture media
• Sinusitis often present by CT scan
  rhinosinusitis might be a better term

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• Common symptoms are sore throat, runny nose,
  nasal congestion, sneezing,
• Sometimes accompanied by conjunctivitis,
  myalgias, fatigue

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The common cold
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Transmission of rhinoviruses

• Direct contact is the most efficient means of
  transmission 40 to 90 recovery from hands.
• Infectious droplet nuclei
• Brief exposure (e.g., handshake) transmits in
  less than 10 of instances
• Kissing does not seem to be a common mode of
  transmission.

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Clinical characteristics

• Incubation period 12-72 hours
• Nasal obstruction, drainage, sneezing, scratchy
  throat
• Median duration 1 week but 25 can last 2 weeks
• Pharyngeal erhema is commoner with adenovirus

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Diagnosis and treatment

• Main challenge is to distinguish between
  uncomplicated cold and streptococcal pharyngitis
  or bacterial sinusitis
• Good examination
• Marked exudate suggests
• Streptococcal infection
• Adenovirus
• Diphtheria
• Rapid antigen tests for group A streptococcus
• Rapid techniques for influenza, RSV,
  parainfluenza
• Treat with NSAIDs and whatever else your
  grandmother advises

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Acute bacterial sinusitis

• Viral infection--gt obstruction of ducts and
  compromise of mucocilary blanket--gt acute
  infection from virulent organisms (most often S.
  pneumoniae and H. influenzae)--gt opportunistic
  pathogens
• Nose blowing generates high intranasal pressures
  that deposit bacteria into the sinus cavity
• Complicates 0.5 of common URI
• More common in adults than in children

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Paranasal sinuses
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Waters view (left) Coronal CT
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Acute sinusitis complications

• Maxillary usually uncomplicated
• Ethmoid cavernous sinus thrombosis (40
  mortality)
• Frontal osteomyelitis of frontal bone cavernous
  sinus thrombosis epidural, subdural, or
  intracerebral abscess orbital extension

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Acute sinusitis complications (2)

• Sphenoid Rare, but usually misdiagnosed, with
  grave consequences extension to internal carotid
  artery, cavernous sinuses, pituitary, optic
  nerves common misdiagnoses include ophthalmic
  migraine, aseptic meningitis, trigeminal
  neuralgia, cavernous sinus thrombosis

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Case

• BR 59 year old white female
• Diplopia and left temporal headache
• Thought to have temporal arteritis
• Started on Prednisone 100mg once daily
• Noted to have 6th nerve palsy
• MRI 9/03 normal

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Case

• Persistent headaches
• CT 10/03 normal, ESR 12 (on steroids)
• Repeat MRI 3/04 showed (2.3/1.5cm) mass in the
  left orbital apex involving the sinus
• Developed left Ptosis, left fixed dilated pupil
  and left 2nd to 6th nerve palsies
• CT head showed 1.5/2 cm hypo dense mass in the
  left basal ganglia

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Chronic sinusitis

• Bacterial Cultures show a variety of
  opportunistic pathogens including anaerobes but
  problem is mainly anatomic, not microbiologic
• Fungal suspect especially when a single sinus is
  involved syndromes associated with nasal
  polyposis can have high morbidity

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Spectrum of fungal sinusitis

• Simple colonization
• Sinus mycetoma (fungus ball)
• Allergic fungal sinusitis
• Acute (fulminant) invasive sinusitis (notably,
  rhinocerebral mucormycosis)
• Chronic invasive fungal sinusitis

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Otitis externa

• Acute, localized often S. aureus or S. pyogenes
• Acute diffuse (swimmers ear) gram-negative
  rods, especially Ps. aeruginosa
• Chronic mainly with chronic otitis media
• Malignant life-threatening infection in
  diabetics Pseudomonas aeruginosa

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Malignant otitis externa

• Diabetes mellitus
• Pseudomonas aeruginosa
• Osteomyelitis of the temporal bone
• Involvement of vital structures at base of brain

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Acute otitis media

• S. pneumoniae and H. influenzae the leading
  causes in all age groups
• Moraxella catarrhalis ? emerging role
• Some case may be viral (RSV, influenza,
  enteroviruses)
• Mycoplasma pneumoniae inflammation of the
  tympanic membrane (bullous myringitis)

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Acute otitis media

• Critical role of eustachian tube as conduit
  between nasopharynx, middle ear, and mastoid air
  cells
• Children have shorter, wider eustachian tubes
  than adults

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Diagnosis and treatment

• Presence of fluid in the middle ear AND
• Ear pain, drainage, hearing loss
• The fluid may take weeks to resolve
• Amoxicillin remains the drug of choice
• Beta-lactamase producing strains of H. influenza
  will need amoxicillin/clavulanic acid or
  cephalosporins

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Chronic otitis media and mastoiditis

• Prolonged middle ear effusions in patients with
  previous episodes of acute otitis media. Often
  skin flora or anaerobic organisms
• Mastoiditis Less common nowadays. formerly
  severe complications. Often anaerobic.

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Acute pharyngitis

• Most cases are viral
• Most important bacterial cause is Streptococcus
  pyogenes (15-20)
• Presents with sore or scratchy throat
• In severe bacterial cases there may be
  odynophagia, fever, headache

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Acute pharyngitis physical exam

• Viral edema and hyperemia of tonsils and
  pharyngeal mucosa
• Streptococcal exudate and hemorrhage involving
  tonsils and pharyngeal walls
• Epstein-Barr virus (infectious mono) may also
  cause exudate, with nasopharyngeal lymphoid
  hyperplasia

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Pharyngoconjuntival fever

• Adenoviral pharyngitis
• Pharyngeal erythema and exudate may mimic
  streptococcal pharyngitis
• Conjunctivitis (follicular) present in 1/3 to 1/2
  of cases commonly unilateral but bilateral in
  1/4 of cases

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Vesicular lesions

• Herpangina
• Uncommon
• Due to coxsackieviruss
• Small, 1-2 mm vesicles on the soft palate, uvula,
  and anterior tonsillar pillars which rupture to
  form small white ulcers
• Occurs mainly in children
• Herpes simplex virus

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Vincents angina and Quinsy

• Vincents angina anaerobic pharyngitis (exudate
  foul odor to breath)
• Ludwigs angina- cellulitis of dental origin
• Quinsy peritonsillitis/peritonsillar abscess.
  Medial displacement of the tonsil often spread
  of infection to carotid sheath

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• Diphtheria
• fibrous pseudomembrane with necrotic epithelium
  and leukocytes

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Diphtheria

• Classic diphtheria (Corynebacterium diphtheriae)
  slow onset, then marked toxicity
• Arcanobacterium hemolyticum (formerly
  Cornyebacterium hemolyticum) exudative
  pharyngitis in adolescents and young adults with
  diffuse, sometimes pruritic maculopapular rash on
  trunk and extremities

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Miscellaneous causes of pharyngitis

• Primary HIV infection
• Gonococcal infection
• Diphtheria
• Yersinia entercolitica (can have fulminant
  course)
• Mycoplasma pneumoniae
• Chlamydia pneumoniae

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Treatment

• Symptomatic
• Penicillin for Strep throat
• Macrolides for pen allergic patients
• Add an antianaerobic agent for Vincents and
  Ludwigs angina

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Acute laryngotracheobronchitis (croup)

• Children, most often in 2nd year
• Parainfluenza virus type 1 most often in U.S.A.
  but other agents are Mycoplasma pneumoniae, H.
  influenza
• Involvement of larynx and trachea stridor,
  hoarseness, cough
• Subglottic involvement high-pitched vibratory
  sounds
• Can lead to respiratory failure (2 get
  hospitalized)

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Croup

• Rhinorrhea, sore throat, mild cough, fever
• Parainfluenzae and influenza can be identified by
  nasopharyngeal swab
• Rapid tests are available
• Treat with vaporizers, nebulized adrenaline
• Systemic or nebulized corticosteroids in the
  severely sick

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Acute epiglottitis

• A life-threatening cellulitis of the epiglottis
  and adjacent structures
• Onset usually sudden (as opposed to gradual onset
  of croup) drooling, dysphagia, sore throat
• H. influenzae the usual pathogen both in children
  (the usual patients) and adults

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Acute suppurative parotitis

• Uncommon, but high morbidity and mortality
• Usually associated with some combination of
  dehydration, old age, malnutrition, and/or
  postoperative state
• S. aureus the usual pathogen

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Deep fascial space infections of the head and neck

• Several syndromes according to anatomic planes
• Can complicate odontogenic or oropharyngeal
  infection
• Ludwigs angina bilateral involvement of
  submandibular and sublingual spaces (brawny
  cellulitis at floor of mouth)

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Deep fascial space infections of the head and
neck (2)

• Lemierre syndrome suppurative thrombophlebitis
  of internal jugular vein (Fusobacterium
  necrophorum)
• Retropharyngeal space infection contiguous
  spread from lateral pharyngeal space or infected
  retropharyngeal lymph node complications include
  rupture into airway, septic thrombosis of
  internal jugular vein

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Severe acute respiratory distress syndrome (SARS)

• Caused by a previously unrecognized
  coronavirusgenome has now been sequenced.
• Clinical manifestations are similar to those of
  other acute respiratory illnessesnotably,
  influenza
• Cases in U.S.associated mainly with travel or as
  secondary contacts

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SARS CDC case definition (2003)

• Respiratory illness of unknown etiology AND
• Measured temperature gt 100.4 degrees F (38
  degrees C) AND
• One or more clinical findings of respiratory
  illness AND
• Travel within 10 days of onset of symptoms to an
  area with documented or suspected cases OR close
  contact with a case

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SARS Case definition (2)

• Clinical findings of respiratory illness cough,
  SOB, dyspnea, hypoxia, or radiographic findings
  of either pneumonia or ARDS
• Travel includes certain areas (mainland China,
  Hong Kong, Hanoi, Singapore) and also airports
  with documented or suspected community
  transmission

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SARS Radiographic findings

• Early a peripheral/pleural-based opacity
  (ground-glass or consolidative) may be the only
  abnormality. Look especially at retrocardiac
  area.
• Advanced widespread opacification (ground-glass
  or consolidative) tending to affect the lower
  zones and often bilateral.
• Pleural effusions, lymphadenopathy, and
  cavitation are not seen.

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Dr. Carlo Urbani (1956-2003)

• 2/28/03 Recognized SARS while examining a
  patient in Hanoi.
• Identified outbreak and raises the alarm.
• Stayed caring patients despite multiple illnesses
  in staffsent wife and three children back to
  Italy
• 3/29/03 Died of SARS

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