Lower Respiratory Tract Infections (LRTI)

Pathogens, signs, symptoms, treatment, clinical parameters for monitoring of Acute Bronchitis, AECB, CAP, HCAP, and Bronchiolitis

  • Acute bronchitis = inflammation of the tracheobronchial tree
    • Cough < 2-3 weeks in duration
    • Usually caused by virus
    • Trxt:  apap/ibu + cough suppressant at night to help w/ sleep + antibiotic if signs of fever, HR> 100, RR > 24 or symptoms lasting longer than 2 weeks
    • Bacterial pathogens of complicated acute bronchitis & AECB:   H. Influenzae, S. Pneumoniae, M. Catarrhalis
      • Antibiotic choices:  macrolide, doxycycline, augmentin, 2nd/3rd generation cephalosporin, fluoroquinalone
  • Bronchiolitis = viral infection of newborns
    • Usually occurs seasonally & is self-limiting but it puts the pt at an increased risk of developing asthma later in life
    • Pathogens:  rhinovirus, parainfluenza virus, RSV
    • Clinical manifestations (often confused w/ acute asthma):  URTI symptoms, tachypnea, wheezing, respiratory distress
    • Diagnosis:  nasal secretions w/ positive viral agents, negative CXR, absence of leukocytosis, H&P
    • Treatment:  antivirals, isolation, oxygen, beta agonists, hospitalization if severe, younger than 6 months old or other underlying conditions
      • Ribavirin:
        • expensive (admin’d via a small particle generator), inhibits both DNA & RNA replication
        • Indications:  PaO2 < 65 or rising PCO2, < 6 weeks old, significant comorbities
      • Palivzumab:
        • Expensive & short shelf life after reconstitution
        • Admin 15mg/kg IM monthly from Nov-April

Lab data useful for diagnosis and monitoring of pneumonia.

  • 2nd most common cause of death next to infectious diseases
  • Lab findings:  increased WBC count with left shift, decreased oxygen saturation, rising PCO2
    • Diagnosis:  radiographic evidence, gram stain or positive blood culture (sputum w/ < 10 epithelial cells/lpf & many PMNs)
    • Need to correctly assess the likelihood of infection  (use the CURB score for CAP–higher the number the higher the risk of infection; CURB-65 doesn’t involve BUN)
  • CURB-65 score (helps to determine the severity of community acquired pneumonia (CAP
    • The higher the CURB score, the higher the risk of infection
    • The modified CURB-65 (CRB-65) score eliminates BUN from consideration
Clinical Factor

Points

Confusion

1

BUN > 19

1

RR ≥ 30

1

Systolic BP < 90 or diastolic BP ≤ 60

1

Age ≥ 65

1

Total Points

?

CURB-65 Score

Percent Mortality

Recommendation

0

0.6

Low risk; may be treated at home

1

2.7

 

2

6.8

Short inpatient hospitalization or closely supervised as an outpatient

3

14

Severe pneumonia; hospitalize and consider ICU admission

4 or 5

27.8

 

  • The modified CURB-65 score classifies severe CAP as a score 3-4
  • Signs/symptoms:
    • Typical symptoms:  cough w/ sputum production, fever/chills, SOB, pleuritic chest pain
    • Atypical symptoms:  HA, dryness, low grade or no fever
    • Physical findings:  rhales, crackles, dullness to percussion, tachypnea, tachycardia, distant breath sounds
      • If a person has any of the following they are considered to have severe pneumonia:
        • respiratory rate > 30/minute
        • respiratory failure by ABG’s
        • mechanical ventilation
        • multilobular involvement  (bilateral pneumonia)
        • Increased radiograph opacity by 50% within 48 hours of admission
        • > 4 hours of vasopressors needed
        • Urine output < 20 ml/min pr < 80 mls over 4 hrs or ARF requiring dialysis
Classification

Etiology

Associated Risk Factors

Community Acquired

Streptococcus pneumon.

Mycoplasma pneumon.

Haemophilus influenzae

Legionella pneumophilia

Klebsiella pneumon.

Splenectomy, DM, URI, young adult, close prox.

Pediatric, elderly

ETOH , diabetic, seizure, Alzheimers

Hospital Acquired/HCAP

Klebsiella pneumon.

Pseudomonas aerugen.

E. Coli

Staph. aureus

Staph. aureus (MRSA)

Mechanical vent., comatose, acid suppressive therapy, NH

Trxt of pneumonia:  antibiotics, hydrate, oxygenate, analgesics/antipyretics

  • In healthy pts:
    • Azithromycin 500mg PO QD x 7-10 days    or     Clarithromycin 500mg PO BID x 10-14 days    or     Doxycycline 100mg PO BID x 10-14 days
      • Alternative trxt:  2nd gen cephalosporin (ex. Cefuroxime) +/- macrolide    or    quinalone
  • In pts w/ cardiopulmonary disease  (COPD/asthma + pneumonia):
    • Cefpodoxime/cefuroxime/augmentin/ceftriaxone + azithromycin/clarithromycin/doxycycline
    • Alternative trxt:  fluoroquinalones (Levofloxacin, ciprofloxacin)
  • Inpatient trxt (not severe disease):  IV azithromycin/doxycycline + IV beta lactam   or  a respiratory fluroquinalone (moxifloxacin, gemifloxacin, levofloxacin)
  • Inpatient w/o risk factors for Pseudomonas & severe disease:  cefotaxime/ceftriaxone + IV azithromycin/a fluoroquinolone
  • Inpatient w/ risk factors for pseudomonas & severe infection:  cefipime/imipenem/monopenem/piperacillin-tazobactam  +  (cipro or aminoglycoside-azithromycin/levaquin) + vanco if MRSA is suspected  (HCAP)
  • Doxycycline, ofloxacin, cipro, levofloxacin, metronidazole, clindamycin all have relatively the same bioavailability IV & PO
    • Generally though, consider switching from IV to PO when:
      • GI tract is functioning well, WBC decrease, there’s an improvement in cough & dyspnea, pts temp < 100 F on at least 2 occasions 8 hrs apart
  • People at risk for drug resistance:  alcoholics, ppl over 65, ppl on immunosuppressive therapy, multiple medical co-morbidities, daycare for kids, ppl on beta-lactam therapy w/in the last 3 months
  • Risk factors for various gram negative bacteria:  nursing homes, recent antibiotic therapy, multiple medical comorbidities, cardiopulmonary disease
    • Very old are more likely to get infected by gram negative & anaerobic pathogens
    • Very young (< 1 mo) are more likely to get infected by Listeria mono or Chlamydia
    • Ppl in their late teens-middle age:  mycoplasma pneumoniae
    • AIDS – Pneumocystis jiroveci (formerly carinii)
    • Alcoholism – Gram negative bacilli &     anerobes
    • COPD – H. influenzae
    • Cystic fibrosis – Pseudomonas aerugenosa
    • Sickle cell anemia – Streptococcus pneum.
    • Viral influenza – Staphylococcus aureus

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