respiratory tract infections in the emergency department
TRANSCRIPT
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Respiratory Tract Infections In the Emergency Department
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Lecture Objectives
Review presentation and diagnosis of respiratory tract infections seen in the emergency department (E.D.)
Discuss and compare different antibiotic treatment regimens for respiratory tract infections
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Respiratory Tract Infections
> 200 million cases per year in U.S.A.10 % of office visits to primary care M.D.'sRx uses 1/2 of outpt. & 1/3 of inpt. antibioticsDirect Rx costs $15 billion per year Indirect Rx costs $9 billion per year
Upper tract infections:–Rhinitis, pharyngitis, sinusitis, otitis, epiglottitis, croup
Lower tract infections:–Tracheitis, bronchitis (acute & chronic), pneumonia
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Lower Respiratory Tract Infections
Incidence–2.5 to 3 million cases per year in U.S.–25 % require hospitalization–? 50,000 deaths per year in U.S.–Account for 28 % of E.D. patients with respiratory symptoms
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Acute Bronchial Infections
Most common etiologic agents:–Hemophilus influenzae (24 %) –H. parainfluenzae (17 %) –Streptococcus pneumoniae (20 %)–Branhamella catarrhalis (11 %)–Neisseria species
Note the top 4 account for 74 %
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Acute Bronchial Infections
Less common etiologic agents:–Klebsiella –Pseudomonas–Staphylococcus aureus–Serratia marcescens–Other streptococci–? % role for mycoplasma & chlamydia
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General Etiologies of Non-Viral Community- Acquired
Pneumonias
Strep. pneumoniae 60 to 75 %Legionella sp. 5 to 15 %Mycoplasma pneumoniae 5 to 18 %Hemophilus influenzae 2 to 5 %Chlamydia pneumoniae 2 to 5 %Staph. aureus 1 to 5 %Branhamella catarrhalis 1 to 5 %
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Risk Factors for Additional Pathogens
(besides Strep. pneumoniae)
COPDAlcoholismDiabetesInstitutionalized"Active cancer"Bronchiectasis
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Conditions Predisposing to Anerobic Lung Infections
Aspiration–Esophageal dysfunction–Suppressed consciousness
ƒ EtOH, drug OD, CVA, Seizure, AnesthesiaGingival infectionsUnderlying lung conditions
–Bronchiectasis, pulmonary infarction, neoplasms, other obstructive lesions
Subphrenic abscessPenetrating chest traumaThoracotomy
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Classical aspiration pneumonia infiltrate (apical posterior segment of the right upper lobe)
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Infiltrates six hours after aspiration
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Causes of Pneumonia Associated with Hilar Adenopathy
AnthraxBlastomycosisCoccidiomycosisHistoplasmosisMycoplasmaPertussisEchovirus
PlaguePsittacosisTularemiaTuberculosisSporotrichosisRubeolaVaricella
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Histoplasmosis with 2 to 5 mm nodules
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Varicella pneumonia in a 24 year old female renal transplant patient
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Bilateral upper lobe cavitary tuber-culosis
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Miliary tuberculosis
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Exudative right upper lobe infiltrate from tuber-culosis
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Tuberculous pneumonia in the left upper lobe with consolidation and cavitation
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Implanted Lucite plastic balls to collapse the upper lobes (old treatment for tuberculosis prior to antibiotics)
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Viruses Causing Pneumonia
Most common:–Influenza–Adenovirus–RSV–CMV–Varicella-Zoster–Measles
Less common:–Parainfluenza–Rhinovirus–Coxsackie–Echovirus–Herpes simplex–Rubella
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Pneumocystis carinii pneumonia
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Pneumocystis carinii pneumonia
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Pneumocystis pneumonia 4 days after a normal chest film
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Sputum silver stain of Pneumocystis carinii
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Pulmonary Kaposi’s sarcoma in an A.I.D.S. patient
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Differential diagnosis of focal infiltrates in immuno-compromised patients
AG
L
S
S
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Malignancy
AP
C
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D
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Differential diagnosis of diffuse interstitial infiltrates in immuno-compromised patients
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Clinical Features of Pneumonia in the Elderly
Main symptoms may be malaise, weakness, stupor, "failure to thrive"
Cough may not be present Fever may not be presentTachypnea/tachycardia may be only signsLeucocytosis may not be presentX-ray findings may be obscured by CHF, COPD, old
TuberculosisResolution often prolongedSepsis and death more frequent
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Indications for Pulse Oximetry when Pneumonia Suspected
Just about everybody !
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Indications for Getting Arterial Blood Gases if Pneumonia
Suspected
O2 saturation < 90 % on O2Pulse oximeter unable to trackAltered mental statusPatient appears to be tiringIntubatedSubjective respiratory distress
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Pneumococcal Pneumonia
Sudden onsetSx: chills, rigors, fever, pleuritic chest
painCough may be initially absentLung consolidation occurs early25 % of patients develop bacteremia5 % overall mortality
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Left upper lobe infiltrate and CHF from Pneumococcal pneumonia
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Sputum gram stain showing Streptococcus pneumoniae
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Sputum gram stain of Streptococcus pyogenes
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Complications of Pneumococcal Pneumonia
ARDSEmpyemaPurulent pericarditisPurulent arthritisMeningitis Endocarditis
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Legionnaire's DiseaseGeneral Risk Factors
Ususally summer to early fallOccurs in all age groupsMiddle-aged males : most frequent1/2 of patients have underlying illness
–Immunosuppression (renal transplants)–Diabetes mellitus–COPD–Renal disease–Neoplasms
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Legionella outbreak at Chambersburg Hospital in Pennsylvania
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Legionnaire's DiseaseSocial and Occupational Risk Factors
SmokingEtOH useConstruction workExcavation of soil nearbyOvernight travel during incubation periodPerson to person transmission very rare ;
resp. isolation of case not needed
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Legionella Pneumonia
Incidence–0.5 to 15 % of community-acquired pneumonias–Up to 30 % of nosocomial pneumonias ( if present in water supply)
If identified in hospital water supply, should attempt to eradicate organism :–Use superheated (> 70 degrees C) water to flush distal outlets–Hyperchlorination of hospital water to 4 to 6 ppm
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Legionnaire's Disease(Legionella pneumophila)
Associated clinical findings:–Fever (continuous, not spiking; > 39.4 C in 80 %)–Malaise (100 %)–Weakness (100 %) : may be chief complaint–Anorexia (100 %)–Cough (92 %) : initially non-productive–Shaking chills (78 %) : usually begin on day 2 to 3–Bradycardia (60 %) : relative to temperature–Diarrhea (50 %) : watery, non-bloody, no abd. pain–Confusion, lethargy (33 %) : may be other CNS sx–Pleuritic chest pain (33 %)
O
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Legionnaire's Disease
Less common clinical findings:–Hemoptysis (25 %) : usually minor–Headache–Myalgias–Arthralgias
Rhinitis & pharyngitis usually absent
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Legionnaire's Disease
Lab and CXR findings:–Few to moderate polys on sputum gram stain–No bacteria on sputum gram stain–Leucocytosis–Elevated SGOT, LDH, Alk phos, bili (50 %)–Hyponatremia (50 %)–Hypophosphatemia–Proteinuria (50 %)–CXR: early patchy infiltrate, later lobar infiltrate
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Legionella pneumonia in left upper and mid lung fields
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Legionnaire's DiseaseConfirmation of Diagnosis
Culture–Charcoal yeast extract agar–Growth evident in 48 to 72 hours
Stains–Direct flourescent antibody (DFA) : best–Gimenez & Dieterla stains : not specific
Serologic–Indirect flourescent antibody (IFA)–Takes 3 to 6 weeks for IFA titer to increase–Dx by 4X increase in titer
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Mycoplasma Pneumonia
Incidence greatest in 10 to 30 year oldsIncubation period 2 to 3 weeksHeadache, malaise, low fever,
nonproductive coughErythema multiforme may occur :
confirms diagnosisBullous myringitis : diagnosticMay also have otitis or non-exudative pharyngitisElevated cold agglutinin titers in second week
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Complications of Mycoplasma Pneumonia
Hemolytic anemiaThrombocytopeniaDICStevens Johnson SyndromeMyocarditis / pericarditisMeningoencephalitisPolyneuritis / myelitisPancreatitisGlomerulonephritisAsthma
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Chlamydia Pneumonia
Fever, cough, mucoid sputumPharyngitis commonMay have laryngitisChest pain / hemoptysis unusualDiagnosis by serology
(microimmunofluorescence)
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Branhamella (Moraxella) catarrhalis Respiratory
Infections
Gram negative diplococciProduce beta-lactamaseCommonly cause COPD exacerbationsFever & leucocytosis in 50 %CXR infiltrates in 40 %
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Staphylococcus aureus Pneumonia
1 to 5 % of all bacterial pneumonias30 % of bacterial pneumonias during
influenza outbreaksOverall mortality 20 %Postinfluenza mortality 50 %
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Sputum gram stain of Staph. aureus
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Conditions Associated with Aerogenous Staph. aureus
Pneumonia
InfluenzaNosocomialInstitutionalizedHIV infectionNeurosurgery
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Right upper lobe infiltrate which progressed to an abscess (note air-fluid level) ; can occur from Staph. or Klebsiella
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General Indications for Admission for Acute Lower Respiratory Tract
Infections
Persistent subjective respiratory distressHypoxemia (O2 sat. < 92 % on room air)Multilobar involvementHypercapnia or acidosisPersistent vomitingFailure of outpatient treatment"Toxic appearance" (altered mental status,
hemodynamic compromise)WBC count < 3000 (?)Comorbid diseases
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Comorbid States Usually Mandating Admission for Treatment of Lower
Respiratory Tract Infections
Age > 65 years (?)Immunosuppressive illness (AIDS, etc.)"Active" cancerCHF exacerbationWheezing exacerbation (COPD)IDDMPoor clearance of secretions
–Neuromuscular disease–NG tube or feeding tube
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Individual Factors NOT Necessarily Mandating Admission for Lower Resp. Tract Infections
FeverLeucocytosisWheezing on presentationPregnancyHemoptysis (if only represents blood -
streaked sputum)
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Requirements for Outpatient Treatment of Pneumonia
Mild clinical findingsNo evident systemic toxicityNo respiratory distressNo hypoxemiaNo underlying diseasesAdequate home support systemAvailability of early followup care
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General Antibiotic Choices for Pneumonia
Aspiration–Cefuroxime / Cefoxitin + aminoglycoside
Community acquired–Azithromycin / erythromycin
Gram negative rods–Same as aspiration +/- quinolone
Staphylococcal–Semisynthetic PCN* / 1st generation cephalosporin
Pneumococcal– PCN*
* May substitute azithromycin / erythromycin if PCN allergic
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Azithromycin Dosing Regimens
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Pathogen–Strep. pneumoniae–Hemophilus influ.–Staph. aureus–Gram neg. bacilli–Legionella pneu.–Agent unknown
Duration (days)–7 to 10–14–14 to 21 (42 ?)–14 to 21–14 to 21–At least 14
Treatment Durations with "Standard" Antibiotics for
Pneumonia
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Relative Contraindications to Use of Quinolones for Pneumonia
Anerobes are suspected main pathogen (aspiration)
Uncomplicated Strep. pneumo. infectionChildren or Pregnancy (? cartilage
growth interference)Suspected chlamydia or mycoplasma
infections
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Medications Causing Reduced Absorption of Quinolones
Aluminum antacidsMagnesium antacidsZinc (in multivitamins)Iron (ferrous sulfate)High dose calcium supplementsSucralfate
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Comparative Advantages of Azithromycin Over Quinolones
No effect on fetal or pediatric cartilageBetter activity against Strep. pneumo.,
Legionella, Chlamydia, & MycoplasmaLesser discontinuance rate (0.2 to 0.7 % vs.
3.5 %)Lesser incidence of side effects (11 % vs. 16
%)No effect on theophylline levels (which are
elevated by quinolones)
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Comparative Advantages of Azithromycin Over Doxycycline
Better activity against Strep. pneumo.Lesser incidence of GI side effectsNo sun exposure sensitivity / dermatitisNo effect on dentitionBetter compliance (less frequent dosing)
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Comparative Advantages of Azithromycin Over Clarithromycin
More reliable / extensive Hemophilus influenzae coverage
Improved compliance–5 day duration vs. 7 to 10 day–Once daily dose vs. bid dose
Less drug interactions (safer)–No prolonged QT / arrhythmia with Seldane or Hismanal–No increased theophylline levels–No increased warfarin levels / effect
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Additional Comparative Advantages of Azithromycin Over Clarithromycin
Longer elimination half life –68 hours vs. 3 to 5 hours
No adverse effects demonstrated on pregnancy outcome and fetal development in animal models (monkeys, rats, mice, rabbits show problems with clarithromycin)
Lesser discontinuance rate –0.2 to 0.7 % vs. 4 %
No metallic taste or aftertasteCost
–$36.00 vs. $56.45 (for standard regimen)
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Study on Cost Efficacy of Azithromycin
Magid DJ, Douglas J, Schwartz JS : "Doxycycline versus Azithromycin in the Treatment of Women with Chlamydia Infections : A Cost-Effectiveness Analysis". Denver General Emergency Medicine Residency and Univ. of Pennsylvania, Presented at SAEM mtg. May 1993. Results: Azithromycin cost $49 per case &
doxycycline cost $55 per case when complications considered
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Goals of Alteration of the Erythromycin Macrolide Ring in Developing New
Macrolides Like Azithromycin
Increased bioavailabilityStability in gastric acidGastrointestinal toleranceBroader antibacterial activityIncreased serum and tissue levelsLonger serum half life
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Other Macrolides Currently Under Study
RoxithromycinMidecamycinJosamycinSpiramycin
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Resolution of Common Pneumonias
Infection
Initial CXR pathology
Radiologic Clearing
Residual CXR Abnor-malities
Strep. pneu. usual 3 to 5 mo. 25 to 35 %
Legionella majority 2 to 6 mo. 10 to 25 %
Mycoplasma unusual 2 to 8 wks. rare
Chlamydia rare 1 to 3 mo. 10 to 20 %
Viral variable variable variable*
* Common with measles, varicella, adenovirus
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Noninfectious Causes of Persistent CXR Infiltrates
Obstructing cancersAdenomasPapillomasLymphomaWegener's GranulomatosisBronchocentric GranulomatosisEosinophilic pneumoniaThromboembolismForeign body aspirationLipoid pneumonia
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Efficacy of Pneumococcal Vaccine Butler et al. JAMA 1993; 270(15): 1826-
31.Condition
–Diabetes–Asplenia–CAD–CHF–COPD–Age > 65
% Efficacy–84–77–73–69–65–75
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Conditions Identified in Butler's JAMA Study for Which Pneumococcal Vaccine
NOT Efficacious
Alcoholism / cirrhosisSickle cell diseaseChronic renal failureLymphoma / leukemiaMultiple myeloma
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Dirithromicin : A Newly Released Oral Macrolide
F.D.A. approved for :–Bronchitis due to Strep. pneumo., Branhamella–Community acquired pneumoniaƒ Pneumococciƒ Mycoplasmaƒ Legionella–Skin & soft tissue infections due to Staph. aureus–Pharyngitis due to group A Strep.
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Pharmacology of Dirithromycin
Hydrolyzed to active erythromycylaminePeak serum concentration in 4 to 5 hoursHalf life 30 hours, permitting once daily dosing
Allergy cross-reactivity with erythromicinHemophilus influenzae is resistantLower serum concentrations than other macrolides
Same GI side effects rate as erythromycin
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Dosage & Cost of the Macrolides
DRUG DOSAGE COST*
Azithromycin 500 mg day 1, 250 mg q d X4
$ 36.23
Clarithromycin 250 to 500 mg bid x 7 days
$ 43.23
Dirithromycin 500 mg q day x 7 days
$ 26.25
Erythromycin(enteric generic)
250 mg qid x 7 days
$ 7.53
Ery-Tab (Abbott)
250 mg qid x 7 days
$ 6.65
ERYC (Parke-Davis)
250 mg qid x 7 days
$ 12.00
*1995