clinical correlations #4 med micro 2008 upper respiratory tract infections

8/14/2019 Clinical Correlations #4 Med Micro 2008 Upper Respiratory Tract Infections

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Upper Respiratory Tract InfectionsUpper Respiratory Tract Infections

Divya Ahuja, M.D.

November 2008

Clinical correlations #4

Med Micro 2008


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Burden of URIBurden of URI

Significant morbidity anddirect health care costs

Direct costs of $ 17

billion annually

Occasionally leads tofatal illness

Excessive use of

antibiotics a major issue


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The Common ColdThe Common Cold

s Children average 8 per year, adults 3s Parainfluenza isolated in 1955s Rhinoviruses 30 to 35%; coronaviruses about 10%,

miscellaneous known viruses about 20%, presumedundiscovered viruses up to 35%, group A streptococci 5% to

10%s Seasonal variation

Rhinovirus early fall Coronavirus- winter

s Day cares are culture medias Sinusitis often present by CT scan; rhinosinusitis might be a

better term


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s Common symptoms are sore throat, runny nose,

nasal congestion, sneezing,

s Sometimes accompanied by conjunctivitis,

myalgias, fatigue


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The common coldThe common cold


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Transmission of rhinovirusesTransmission of rhinoviruses

s

Direct contact is the most efficient means oftransmission: 40% to 90% recovery from

hands.

s Infectious droplet nuclei

s Brief exposure (e.g., handshake) transmits in

less than 10% of instances

s Kissing does not seem to be a common mode

of transmission.


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Clinical characteristicsClinical characteristics

s Incubation period 12-72 hours

sNasal obstruction, drainage, sneezing,

scratchy throat

s Median duration 1 week but 25% can last 2weeks

s Pharyngeal erhema is commoner with

adenovirus


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Diagnosis and treatmentDiagnosis and treatment

s Main challenge is to distinguish between uncomplicatedcold and streptococcal pharyngitis or bacterial sinusitis Good examination

s Marked exudate suggests Streptococcal infection

Adenovirus Diphtheria

s Rapid antigen tests for group A streptococcuss Rapid techniques for influenza, RSV, parainfluenzas Treat with NSAIDs and whatever else your grandmother

advises


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Acute bacterial sinusitisAcute bacterial sinusitis

s Viral infection--> obstruction of ducts and compromiseof mucocilary blanket--> acute infection from virulentorganisms (most often S. pneumoniae andH.influenzae)--> opportunistic pathogens

s Nose blowing generates high intranasal pressures that

deposit bacteria into the sinus cavitys Complicates 0.5% of common URI

s More common in adults than in children


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Paranasal sinusesParanasal sinuses


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Waters view (left); Coronal CTWaters view (left); Coronal CT


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Acute sinusitis: complicationsAcute sinusitis: complications

sMaxillary: usually uncomplicated

sEthmoid: cavernous sinus thrombosis(40% mortality)

s Frontal: osteomyelitis of frontal bone;cavernous sinus thrombosis; epidural,subdural, or intracerebral abscess;

orbital extension


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Acute sinusitis: complications (2)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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CaseCase

s BR 59 year old white female

s Diplopia and left temporal headache

s Thought to have temporal arteritis

s

Started on Prednisone 100mg once dailys Noted to have 6th nerve palsy

s MRI 9/03 normal


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CaseCase

s Persistent headaches

s CT 10/03 normal, ESR 12 (on steroids)

s Repeat MRI 3/04 showed (2.3/1.5cm) mass in the left

orbital apex involving the sinus

s Developed left Ptosis, left fixed dilated pupil and left

2nd to 6th nerve palsies

s CT head showed 1.5/2 cm hypo dense mass in the left

basal ganglia


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Chronic sinusitisChronic 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 sinusitisSpectrum of fungal sinusitis

Simple colonization

Sinus mycetoma (fungus

ball)

Allergic fungal sinusitis

Acute (fulminant) invasive

sinusitis (notably,

rhinocerebral mucormycosis)

Chronic invasive fungalsinusitis


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Otitis externaOtitis externa

Acute, localized: often S. aureus or

S. pyogenes Acute diffuse (swimmers ear):

gram-negative rods, especiallyPs.aeruginosa

Chronic: mainly with chronic otitismedia

Malignant: life-threateninginfection in diabetics;Pseudomonas

aeruginosa


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Malignant otitis externaMalignant otitis externa

Diabetes mellitus

Pseudomonas

aeruginosa

Osteomyelitis ofthe temporal bone

Involvement of

vital structures atbase of brain


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Acute otitis mediaAcute otitis media

s S. pneumoniae andH. influenzae theleading causes in all age groups

s Moraxella catarrhalis: ? emerging role

s

Some case may be viral (RSV, influenza,enteroviruses)

s Mycoplasma pneumoniae: inflammation ofthe tympanic membrane (bullous

myringitis)


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Acute otitis mediaAcute otitis media

Critical role ofeustachian tube asconduit betweennasopharynx, middle

ear, and mastoid aircells

Children have shorter,wider eustachian tubes

than adults


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Diagnosis and treatmentDiagnosis and treatment

s Presence of fluid in the middle ear AND

s Ear pain, drainage, hearing loss

s The fluid may take weeks to resolve

s Amoxicillin remains the drug of choice

s Beta-lactamase producing strains of H.

influenza will need amoxicillin/clavulanic

acid or cephalosporins


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Chronic otitis media and mastoiditisChronic otitis media and mastoiditis

s Prolonged middle ear effusions in

patients with previous episodes of

acute otitis media. Often skin flora or

anaerobic organismssMastoiditis: Less common nowadays.

formerly severe complications. Often

anaerobic.


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Acute pharyngitisAcute pharyngitis

s Most cases are viral

s Most important bacterial cause is

Streptococcus pyogenes (15-20%)

s Presents with sore or scratchy throats In severe bacterial cases there may be

odynophagia, fever, headache


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Acute pharyngitis: physical examAcute pharyngitis: physical exam

sViral: edema and hyperemia of tonsilsand pharyngeal mucosa

s Streptococcal: exudate and hemorrhage

involving tonsils and pharyngeal wallssEpstein-Barr virus (infectious mono):

may also cause exudate, withnasopharyngeal lymphoid hyperplasia


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Pharyngoconjuntival feverPharyngoconjuntival fever

sAdenoviral pharyngitis

s Pharyngeal erythema and exudate may

mimic streptococcal pharyngitis

sConjunctivitis (follicular) present in

1/3 to 1/2 of cases; commonly

unilateral but bilateral in 1/4 of cases


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Vesicular lesionsVesicular lesions

s 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

s Herpes simplex virus


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Vincents angina and QuinsyVincents angina and Quinsy

s Vincents angina: anaerobic pharyngitis(exudate; foul odor to breath)

s Ludwigs angina- cellulitis of dental origin

s Quinsy: peritonsillitis/peritonsillar abscess.Medial displacement of the tonsil; often

spread of infection to carotid sheath

sDiphtheria


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Diphtheria

sfibrous pseudomembrane with necrotic epithelium and leukocytes

Di h h iDi hth i


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DiphtheriaDiphtheria

s

Classic diphtheria (Corynebacteriumdiphtheriae): slow onset, then marked toxicity

sArcanobacteriumhemolyticum (formerly

Cornyebacteriumhemolyticum): exudative

pharyngitis in adolescents and young adultswith diffuse, sometimes pruritic maculopapular

rash on trunk and extremities

Mi ll f h itiMi ll f h iti


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Miscellaneous causes of pharyngitisMiscellaneous causes of pharyngitis

s Primary HIV infectionsGonococcal infection

sDiphtheria

s Yersiniaentercolitica (can havefulminant course)

sMycoplasmapneumoniae

sChlamydiapneumoniae


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TreatmentTreatment

s Symptomatics Penicillin for Strep throat

s Macrolides for pen allergic patients

s Add an antianaerobic agent for Vincentsand Ludwigs angina


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Acute laryngotracheobronchitis (croupAcute laryngotracheobronchitis (croup)

s

Children, most often in 2nd years Parainfluenza virus type 1 most often in U.S.A. but other

agents are Mycoplasma pneumoniae, H. influenza

s Involvement of larynx and trachea: stridor, hoarseness,

coughs Subglottic involvement: high-pitched vibratory sounds

s Can lead to respiratory failure (2% get hospitalized)


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CroupCroup

s Rhinorrhea, sore throat, mild cough, fevers Parainfluenzae and influenza can be identified by

nasopharyngeal swab

s Rapid tests are available

s Treat with vaporizers, nebulized adrenalines Systemic or nebulized corticosteroids in the severely

sick

Acute epiglottitisAcute epiglottitis


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Acute epiglottitisAcute epiglottitis A life-threatening

cellulitis of the epiglottisand adjacent structures

Onset usually sudden (asopposed to gradual onset

of croup); drooling,dysphagia, sore throat

H. influenzae the usualpathogen both in children

(the usual patients) andadults

Acute suppurativeAcute suppurative


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Acute suppurativecute suppu at ve

parotitisparotitis

sUncommon, but highmorbidity and mortality

sUsually associated with

some combination ofdehydration, old age,malnutrition, and/orpostoperative state

s S. aureus the usualpathogen

Deep fascial space infections ofDeep fascial space infections of


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the head and neckthe head and neck

s Several syndromes according to anatomicplanes

s Can complicate odontogenic or

oropharyngeal infections Ludwigs angina: bilateral involvement of

submandibular and sublingual spaces

(brawny cellulitis at floor of mouth)



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the head and neck (2)the head and neck (2)

s Lemierre syndrome: suppurative thrombophlebitisof internal jugular vein (Fusobacterium

necrophorum)

s

Retropharyngeal space infection: contiguousspread from lateral pharyngeal space or infected

retropharyngeal lymph node; complications

include rupture into airway, septic thrombosis of

internal jugular vein

Severe acute respiratorySevere acute respiratory


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Severe acute respiratorySeve e cu e esp o y

distress syndrome (SARS)distress syndrome (SARS)

s Caused by a previously unrecognizedcoronavirusgenome has now been

sequenced.

s Clinical manifestations are similar to

those of other acute respiratory

illnessesnotably, influenza

s Cases in U.S.associated mainly

with travel or as secondary contacts

SARS CDC d fi iti (2003)SARS CDC d fi iti (2003)


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SARS: CDC case definition (2003)SARS: CDC case definition (2003)

s Respiratory illness of unknown etiology ANDs Measured temperature > 100.4 degrees F (38

degrees C) AND

s One or more clinical findings of respiratory illnessAND

s Travel within 10 days of onset of symptoms to anarea with documented or suspected cases OR close

contact with a case

SARS C d fi iti (2)SARS C d fi iti (2)


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SARS: Case definition (2)SARS: Case definition (2)

s Clinical findings of respiratory illness:cough, SOB, dyspnea, hypoxia, or

radiographic findings of either pneumonia

or ARDS

s Travel includes certain areas (mainland

China, Hong Kong, Hanoi, Singapore) and

also airports with documented or suspected

community transmission

SARS: Radiographic findingsSARS: Radiographic findings


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SARS: Radiographic findingsSARS: Radiographic findings

s Early: a peripheral/pleural-based

opacity (ground-glass orconsolidative) may be the only

abnormality. Look especially at

retrocardiac area.

s Advanced: widespread

opacification (ground-glass orconsolidative) tending to affect the

lower zones and often bilateral.

s Pleural effusions,

lymphadenopathy, and cavitation

are not seen.

D C l U b i (1956 2003)Dr Carlo Urbani (1956 2003)


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Dr. Carlo Urbani (1956-2003)Dr. Carlo Urbani (1956-2003)

s 2/28/03: RecognizedSARS while examining apatient in Hanoi.

s Identified outbreak andraises the alarm.

s Stayed caring patientsdespite multiple illnessesin staffsent wife andthree children back to Italy

s 3/29/03: Died of SARS


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clinical correlations #4 med micro 2008 upper respiratory tract infections

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