LRTI Flashcards
Lower respiratory tract
Starts at the trachea–>bronchi–>bronchioles–>alveoli
Alveoli–>site of gas exchange where pneumonia occurs
Nasopharynx
Nasal hair–>net captures pathogens
IgA secretion–>binds to pathogens
Fibronectin–>binds to pathogens
Oropharynx
Saliva–>form that can remove bacteria or transfer
Slough epithelial cells–>gets rid of attached bacteria to collect in saliva
Trachea/bronchi
Cough
Mucociliary apparatus (cilia)
Epiglottic reflux
Alveoli
Alveolar lining fluid–>reduce binding to pathogens
Macrophages + PMN–>innate immunity
Cell-mediated immunity–>T and B cells
Pathogen-mediated
Surface adhesions–>grab the cell
Pili–>grab the cell
Exotoxins–>fight immune cells
Enzymes–>fight immune cells
Host interventions
Smoking–>decreased mucociliary apparatus
Alcohol
Altered consciousness
Endotracheal tubes
Host-disease States
Immunosuppression
Diabetes
Asplenia–>decreased immune system
Elderly–>decreased immune system
What is community-acquired pneumonia?
Pneumonia that developed outside of the hospital or within 48 hours of hospital admission
Most common infection-related hospitalization and mortality in the US
Pathogenesis of CAP
Aspiration–>most common with bacterial
- occurs during healthy individuals and sleep
- organisms are usually cleared if host defenses functioning properly
Aerosolization–>most common with bacterial
- direct inhalation of pathogen in droplet nuclei form
Bloodborne
Streptococcus pneumoniae (gram +)
Prevalence: asplenia, immunocompromised, chemo
Resistance: penicillin, macrolide
- Age < 6 or > 65
- Prior antibiotics
- Recent hospitalization
- Close quarters
- Co-morbid conditions
Haemophilus influenzae
gram (-)
Legionella pneumophila–> atypical
Spread: aerosolization
Risk: older males, chronic bronchitis, smokers, immunocompromised
Chlamydia pneumoniae
atypical
Mycoplasma pneumoniae–> atypical
Spread: person-to-person contact
2-3 week incubation period followed by slow onset of symptoms
- persistant, non-productive cough–> “walking pneumonia”
Staphylococcus aureus
Prevalence: very low
Risk factors for MRSA
- 2-14 days post influenza
- Previous MRSA infection
- Previous hospitalization
- Previous IV antibiotic
Predictive values: 95-99% negative, 56.8% positive
Classic presentation
Sudden onset
Fever, chills, pleuritic chest pain, SOB, productive cough
Gradual onset with mycoplasma and chlamydia
Elderly presentation
May be absent
Decreased functional status, weakness, mental status changes
Vitals
Febrile: < 38 C
Tachycardia: HR > 90
Hypotensive: SBP < 90
Tachypnea: RR > 20
Labs
WBC–>leukocytosis
SCr (elevated), BUN (elevated), LFTs
Low pulse oximetry
Nasopharyngeal PCR swab–> MRSA, viral
Urinary antigen tests–> strep pneumo, legionella
Major criteria for severe CAP
Need 1
Septic shock requiring vasopressors
Respiratory failure required mechanical ventilation
Minor criteria for severe CAP
Need 3
RR > 30
BUN > 20
WBC < 4,000
Plt < 100,000
T < 36 C
SBP < 90
Multilobe infiltrates
Confusion/disorientation
Diagnosis
Chest radiography: Recommended for all patients for CAP
- Dense lobar consolidation/infiltrates = bacterial origin
- Patchy, diffuse, interstitial infiltrates = atypical or viral
Sputum: Color, amount, consistency, odor
Procalcitonin: Biomarker specifically for bacterial
- Dictates duration, not antibiotics
Blood culture–>only used in severe
Respiratory culture–>only used in severe
- Negative in 40-50% in patients with CAP
Supportive treatment
Humidified O2
Bronchodilators
Fluids
Chest physiotherapy
Empiric therapy–>OUTPATIENT
Healthy, no comorbidities/risk factors
Minimum of 5 total days
Amoxicillin 1 g PO q8h
Doxycycline 100 mg PO BID
Azithromycin (z-pak)–>ONLY IF MACROLIDES RESISTANCE < 25%
Empiric therapy–>OUTPATIENT
Healthy, comorbidities/risk factors
Heart, lung, renal, DM, alcoholism, malignancy, immunosuppression
Respiratory FQ (Levofloxacin or Moxifloxacin)
Beta-lactam + macrolide/doxycycline–>preferred
- Augmentin
- Cefuroxime
- Cefpodoxime
Empiric therapy–> INPATIENT
Non-severe: no MRSA/P, aeruginosa risk factors
Respiratory FQ (Levofloxacin or Moxifloxacin)
Beta-lactam + macrolide/doxycycline–>preferred
- Unasyn
- Ceftriaxone
Empiric therapy–>INPATIENT
Severe CAP: no MRSA/P. aeruginosa risk factors
Respiratory FQ + Beta-lactam
Beta-lactam + macrolide/doxycycline–>preferred
- Unasyn
- Ceftriaxone
If patient has MRSA risk factors
Above agents + vancomycin/linezolid
P. aeruginosa risk factors
Previous isolated infection, previous hospitalization in 90 days
Above agents + Zosyn/cefepime/meropenem
ONLY USE STEROIDS IF CAP + SEPTIC SHOCK
What is HAP/VAP?
HAP: pneumonia occurring > 48 hours after hospital admission
VAP: pneumonia occurring > 48 hours after endotracheal intubation
Pathogenesis of HAP/VAP
Micro-aspiration of oropharnygenal secretions that colonized with bacteria
- Gram (+) colonization–>3-5 days–>gram (-) organism
Aspiration
Direct inoculation
Hematogenous
Common pathogens of HAP/VAP
Gram (-): P. aeruginosa, enterbacteriales, acinetobacter
Gram (+): Staphylococcus aureus
Risk factors for HAP/VAP
Age
Duration of hospitalization
Endotracheal intubation
Nasogastric tube
Surgery
Previous antibiotic therapy
Severity of comorbid disease
Altered mental status
Risk factors for MDR HAP
Prior IV antibiotic use within 90 days
Risk factors for MRSA HAP/VAP
Prior IV antibiotic use within 90 days
Risk factors for P. aeruginosa MDR
Prior IV antibiotic use within 90 days
Risk factors for MDR VAP
Prior IV antibiotic use within 90 days
Septic shock at time of diagnosis
Acute respiratory distress syndrome prior to diagnosis
Acute renal replacement therapy prior to diagnosis
> 5 days hospitalization prior to diagnosis
Microbiology Testing
Respiratory cultures–>recommended for all patients
-Noninvasive> invasive
- If invasive–> BAL > 10 ^4–>diagnosis
Diagnosis for HAP/VAP
no gold standard
Timing–> 48 hours from admission
Presentation–>clinical signs + new ling infiltrates
HAP–>low risk for mortality (no septic shock or ventilation)
Goal: MSSA + P. aeruginosa
Zosyn, Cefepime, Meropenem, Imipenem, Levofloxacin
HAP–>low risk for mortality (no septic shock or ventilation) + MRSA
Zosyn, Cefepime, Meropenem, Imipenem, Levofloxacin + Vancomycin/Linezolid
HAP–>high risk for mortality (septic shock or ventilation) + MRSA
Goal: MRSA + P. aeruginosa
2 of the following (1 b-lactam + 1 non-b-lactam)
Zosyn, Cefepime, Meropenem, Imipenem, Levofloxacin, Tobramycin/Amikacin+ Vancomycin/Linezolid
VAP
Goal: MRSA + P. aeruginosa
Zosyn, Cefepime, Meropenem, Imipenem, Levofloxacin, Tobramycin/Amikacin+ Vancomycin/Linezolid
Non-beta-lactam considerations
Daptomycin–>never use for LRTI
Aminoglycosides–>recommend against monotherapy
Polymyxins–>reserved for pts with high prevalence of MDR
Tigecycline–>good for polymicrobial infections
Duration for HAP/VAP
7 days if clinically stable
