Pneumonia

Pneumonia is an infection of the lung parenchyma. It is important to know where the infection was acquired, risk factors for more severe infections, and local resistance patterns to guide management of pneumonia.

Classification

 * Community acquired: pneumonia acquired outside the hospital or long term care facility. Most common type of pneumonia. Have to be >14 days outside hospital or LTC.
 * Hospital acquired pneumonia (nosocomial): pneumonia occuring >48 hours after admission to hospital
 * Healthcare associated pneumonia: occurs in non-hospitalized patient with extensive healthcare contact e.g. Iv therapy, wound care, IV chemotherapy within 30 days, residence in LTC/nursing home, hospitilization for 2+ days within 90 days, hemodialysis within past 30 days (treat similarly to hospital acquired pneumonia**)

Common Organisms

 * Community acquired: Streptococcus pneumonia,  h.influenza,  mycoplasma pneumoniae, chlamydia pneumonia, multiple viruses
 * Comorbidity: ETOH, elderly,smoking, respiratory disease (asthma, COPD, lung Ca), immunosuppression, asplenia, hospitalization in last 3 months, chronic heart/lung, liver/renal disease, diabetes mellitus
 * Hospital acquired pneumonia: as above +, klebsiella, e.coli, pseudomonas, staph aureus, group A strep, actinobacter
 * Other: HIV (pneumocystis jiroveci, mycobacterium avium complex), poor dentition (anaerobes), exposure to birds (chlamydia psittaci), travel history (mycobacterium tuberculosis -TB exposure), living/work environment (legionella pneumonia - hot tubs, humidifiers, air conditioning), coxiella burneii (exposure to infected farm animals), bronchiectasis (increases risk of pseudomonas)
 * Risk factors for MRSA: IVDU, homeless, incarceration, health care workers, recent hospitalizations

Clinical

 * History: Cough (+/- productive), fever/chills, SOB, pleuritic chest pain, +/- hemoptysis
 * Physical: febrile, vitals, cough, increase WOB, localized crackles, bronchial breath sounds, dullness to percussion, decreased air entry, increased tactile fremitus, egophony, pulse oximetry
 * IMPORTANT: in patients presenting with atypical features especially elderly patients always keep pneumonia on differential e.g. delirium, GI symptoms, abdominal pain, functional decline
 * No combination of signs and symptoms have been validated to rule in or rule out pneumonia

Investigations

 * CXR PA and lateral
 * Consider: CBC, lytes, Cr, ABG, blood cultures, +/- sputum cultures
 * False negatives can occur -  consider in patients with immunodeficiency, HIV, dehydration, neutropenia, PCP infection, first 24hours of infection

Severity Scoring System

 * C- confusion
 * U - Uremia (may not have available)
 * R - Respiratory rate > 30 breaths/minute
 * B - Blood pressure sBP < 90 or dBP < 60
 * 65 - age >65
 * If score >/= 3 (admit urgently), 2 (same day assessment required), 0-1 (treatment at home may be okay)
 * It is important to take into account physician judgement in addition to scoring system. Identify those at high risk for complicated course and would benefit from hospitalization, even though clinically they may apear stable.
 * If score is >3, unable to take oral medications, compliance may be an issue, pulse oximetry < 90% --> admit
 * It is important to reassess and re-evaluate freuently to assess severity of disease and monitor for decompensation: ICU admission, hospital admission or frequent f/u in community

Prevention

 * See vaccination section
 * Pneumococcal vaccine, influenza vaccine
 * Stop smoking
 * Hand hygiene practices

Management - ADULT

 * ABCs, decision to admit, constant reassessment
 * Hydration, analgesics, antipyretics, oxygen PRN, antibiotics
 * It is important to know local resistance patterns and patient's antibiotic history before prescribing Abx
 * Fluroquinolones should be reserved for treatment failures, comorbidities with reent abx use, allergies, or history of highly resistant respiratory pathogens
 * CAP: Duration of therapy: minimum of 5 days, should be 48-72 hours afebrile and clinically stable before discontinuing antibiotics. Typically duration of abx varies from 7-14 days.
 * Ensure to treat other comorbidities at the same time as pneumonia e.g. COPDAE with steroids
 * Watch out for drug interactions with antibiotics - review medications prior to prescribing
 * ​e.g. penicillins, macrolides, fluroquinolones - increase anticoagulation effect of warfarin
 * e.g. macrolides and fluroquinolones can prolong QTc
 * e.g. sulfas and ACEI can cause hypoerkalemia

CAP without comorbidity (mild/moderate)

 * Genearl approach: all CAP should at minimum have coverage for atypicals
 * First line:
 * Azithromycin 500mg PO daily x 1 day then 250mg PO daily x 4 days
 * Clarithromycin 500mg PO BID
 * Amoxicillin 1 gram TID (can be considered in patients over >50 years of age where mycoplasma infection less likely
 * Second line:
 * Doxycycline 100mg PO BID on first day then 100mg PO daily

Outpatient with comorbidity/modifying factors (mild/moderate)

 * Comorbidity: ETOH, elderly,smoking, respiratory disease (asthma, COPD, lung Ca), immunosuppression, asplenia, hospitalization in last 3 months, chronic heart/lung, liver/renal disease, diabetes mellitus
 * Combination treatment:


 * ​Beta lactam agents:


 * ​Amoxicllin 1 gram PO TID
 * Amox/Clav 500 mg PO TID or 875 mg PO BID
 * Cefuroxime (ceftin) 500mg PO BID
 * Cefprozil 500mg PO BID
 * Coverage for atypicals


 * ​Clarithromycin/azithromycin/doxycycline (as above)
 * Fluroquinolones:
 * Levofloxacin 750 mg PO daily x 5 days
 * Moxifloxacin 400mg Po daily
 * Suspected aspiration (polymicrobial, oral anaerobes, gram negative bacilli)
 * Amoxicillin/Clavulanate 500mg PO TID or 875mg PO BID
 * Clindamycin 300-450mg PO QID

Longterm Care (mild-moderate)

 * Same as outpatient with comorbidity/modifying factors

Community acquired (severe) - admit

 * Combination treatment
 * Cefotaxime 1-2 grams q 8hours, or ceftriaxone 1-2 grams q24 hours, or amoxicillin 1 gram TID, or amox/clav 500mg TID/875mg BID
 * ++++ clarithromycin/azithromycin IV/doxycycline
 * Fluroquinolone
 * Levofloxacin 750mg PO/IV daily
 * Moxifloxacin 400mg PO/IV daily
 * Switch from IV to PO (usually within first 3 days) when hemodynamically stable, improving clinically, able to tolerate PO and normal functioning GI tract


 * Oral options: Can step cefoxamine/ceftriaxone down to cefuroxime +/- azithromycin
 * Levofloxacin 750 mg PO daily
 * Duration of therapy:
 * 5 days: if not immunocompromised and no structural lung disease
 * 7 days: if moderately immunocompromised+/- bilobar pneumonia +/- structural lung disease
 * 10 days: if slow clinical response or severely immunocompromised
 * Note azithromycin should only be given for maximum 5 days

Community acquired (severe) - ICU

 * severe pneumonia requiring ICU: hypoxemia despine O2 supp, RR>30, need for ventilator support, shock
 * Combination therapy
 * Cefotaxime IV or ceftriaxone
 * +++ clarithromycin/azithromycin OR levofloxacin/moxifloxacin
 * Alternative: fluroquinolone + clindamycin

Other considerations:

 * If MRSA is suspected --> add vancomycin or linezolid
 * If pseudomonas is suspected/cultured--> treatment is aminoglycoside + anti-pseudomonal b-lactam
 * Risk factors for pseudomonas: bronchiectasis, ETOH, frequent abx courses, recent abx use past 3 months, chronic oral steroids, recent hospital stay
 * Ciprofloxacin PO/IV + cefepime IV or ceftazidime IV or pip/tazo or imipenum/cilastatin or meropenum

Hospital acquired pneumonia (HAP)

 * IV ceftriaxone 1-2grams IV q24 hours
 * OR IV pip/tazo 3.375 grams q 6hours
 * OR levofloxacin 750mg q24 hours

Ventilator Associated

 * Early < 5 days: treat same as hospital acquired pneumonia
 * Late > 5 days: IV pip/tazo
 * OR cipro + cefazolin 2 grams q 8 hours
 * OR meropenum 500mg IV q 6 hours

Outpatient

 * 1-3 months: consult specialist. Outpatient patient not recommended
 * 3 months- 5 years (preschool)
 * RSV/other viruses --> no treatment. Most frequent cause in children < 5 years old.
 * First line:
 * amoxicillin 80mg/kg/day divided TID x 7-10 days
 * OR amox/clav 80mg/kg/day divided BID
 * B-lactam allergy: clarithrymycin 15mg/kg/day divided BID x 7-10 days
 * OR azithromycin 10mg/kg/day on first day then 5mg/kg/day x 4 days
 * 5-18 years
 * Clarithromycin (max 1 gram/day), azithromycin - dosing as above
 * Doxycycline 2-4mg/kg/day divided BID - over 8 years old. Maximum 200mg/day

Hospital

 * Consider hospitilization if < 1month of age, toxic, severe respiratory distress, requiring oxygen, dehydration, vomiting, no response to oral medications, immunocompromised, hypotension, empyema, lung abscess
 * 1-3 months: consult specialist
 * 3 months - 5 years
 * Combination therapy:
 * ampicillin IV/cefuroxime/ceftriaxone/cefotaxime
 * +/- coverage for atypical: clarithrymycin/azithromycin/erythromycin
 * no macrolides in patients < 6 months of age
 * 5-18 years: same as for age groups 3months -5 years with coverage for atypicals

Differential

 * In patients not responding to initial management it is important to reassess the diagnosis, identify other contributing causes, consider antibiotic coverage, consider atypical pathogents, and complications of pneumonia.
 * Most patients hould improve clinically within 3 days
 * DDX: lung cancer, pulonary embolism, CHF, foreign body aspiration
 * Complications: parapneumonic effusion, pneumothorax, empyema, undiagnosed underlying condition (lung cancer, cystic fibrosis)
 * Consider: repeating investigations, expanding abx coverage, specialist consultation

Follow-up

 * Ensure timely follow-up to monitor for clinical improvement/decompensation
 * Consider repeat CXR in 6 weeks if extensive/necrotizing pneumonia, smoker, ETOH, COPD, >5 % weight loss in 40 years
 * Reportable diseases to public health - may need contact tracing and prophlyaxis: legionella, TB, SARS, influenza, hantavirus pulmonary syndrome, invasive group A strep

Resources

 * Anti-infective guidelines for community acquired infections 2013
 * TOH algorithm for CAP
 * http://www.aafp.org/afp/2011/0601/p1299.html