Exam 3- Lower Respiratory Tract infections (pneumonia) Flashcards
Where does the split occur that divides upper respiratory tract infections from lower respiratory tract infections?
The split occurs at the neck
Anything above the neck is an URTI
Anything below the neck is a LRTI
Where does pneumonia typically occur?
The alveoli of the lungs
What are the 4 mechanisms of host defense against respiratory tract infections?
Nasopharynx
Trachea/Bronchi
Oropharynx
Alveoli/Terminal Airways
What are examples of nasopharynx host defense mechanisms?
These are defenses associated with the nose and areas around the nose
*Nasal hair
-Anatomy of upper airways
-IgA secretion
-Mucociliary Apparatus
-Fibronectin
What are examples of trachea/bronchi host defense mechanisms?
These are defenses of the trachea and bronchi found in the lungs, they are used to DECREASE BACTERIAL LOAD
*Cough
*Epiglottic reflex (epiglottic closes to prevent aspiration of particles down the trachea)
-Anatomy of conducting airways
-Mucociliary apparatus
-Immunoglobulin
What are examples of oropharynx host defense mechanisms?
These are associated with the mouth
*Saliva
*Slough epithelial cells (shedding, helps get rid of attached bacteria to be removed by the saliva)
-Complement production
What are examples of alveoli/terminal airway host defense mechanisms?
Found in the lung, these are sites associated with gas exchange. Most defenses are immune-mediated
-Alveolar lining fluid
-Cytokines
-Macrophages +PMNs
-Cell-mediated immunity (B and T cells)
What are the 4 reasons why host defense mechanisms against a pathogen may not work?
-*Pathogen-mediated
(mutations increase ability to infect)
-Host Interventions
(smoking, alcohol)
-Defenses gone wrong
(alveolar amcrophages)
Host disease states
(immunosuppression, etc)
What host interventions may reduce innate defense mechanisms against pathogens and how do they do this?
Smoking- decreases mucociliary apparatus (cilia), increases mucus
Alcohol- decreases epiglottic reflux, increasing likelihood of aspiration
Altered level of consciousness
Endotracheal tubes
What host disease states may decrease innate defense mechanisms against pathogens?
*Immunosuppression
-Diabetes
-Asplenia
-Elderly
What is the definition of “Community-Acquired Pneumonia”?
Pneumonia that developed outside of the hospital OR within 48 hours of hospital admission
What is the most common cause of infection-related hospitalization and mortality?
Community Acquired Pneumonia
What are the 3 mechanisms of pathogenesis of Community-Acquired Pneumonia?
Aspiration
-most common
-common during sleep or in disorders that impair consciousness and depress gag reflex resulting in increased inoculum
Aerosolization
-Direct inhalation of pathogen (virus)
-Droplet nuclei= particles containing pathogen
Bloodborne
-Translocate to pulmonary site
-Uncommon
I-Clicker: Which microorganism class is the most common pathogenic organism for CAP?
A. Fungus
B. Bacteria
C. Virus
D. Protozoa
C. Virus
True or False: Viruses normally resolve by themselves and do not require antibiotics
True
-although viruses are the most common cause of CAP, we are going to be focusing on the bacterial causes
What are the common bacterial pathogens of CAP?
Streptococcus pneumonia (G+)
Haemophilus influenzae (G-)
*Atypical Pathogens:
-Mycoplasma pneumoniae
-Legionella pneumophila
-Chlamydia pneumoniae
Staph aureus (in more serious infections)
What are the atypical pathogens that are common in CAP?
Mycoplasma pneumonia
Legionella pneumophila
Chlamydia pneumoniae
What 3 drug classes cover atypical pathogens?
Fluoroquinolones (“flox”)
Macrolides (“Eryth, Clarith, Azith”)
Tetracyclines (“Tetra, Doxy, Mino”)
What are the typical characteristics of Streptococcus pneumoniae?
Increased prevalence + severity in patients with medical condition risk factors (asplenia, diabetes, immunocompromised, etc)
Resistance to penicillins + macrolides is concerning. Risks include:
-Old (>65) or young (<6)
-Prior abx use
-Co-morbid conditions
-Day care
-Recent hospitalization
-Close quarter living
What are the typical characteristics of Mycoplasma pneumoniae?
Atypical bacteria (not identified on gram stain)
Spread by person-to-person contact (higher risk in close-quarter living)
2-3 week incubation with slow symptom onset
Imaging is more pronounced with patchy, interstitial infiltrates
What are the typical characteristics of Legionella pneumophila?
Atypical pathogen
*Found in soil + water
Spread by aerosolization
Risk factors: older males, bronchitis, smokers, immunocompromised
Multisystem involvement is common, leads to more severe symptoms
When it is believed that a CAP patient has a Staph aureus infection, what test needs to be done?
MRSA nasal PCR
95-99% negative predictive value for MRSA in CAP
But only 56.8% positive predictive value
*Does a great job of telling you that you do NOT have MRSA
What is the common symptom presentation of CAP?
Sudden onset of:
-Fever
-Chills
-Pleuritic chest pain
-Dyspnea
-Productive cough
*Note that Mycoplasma and Chlamydia pneumoniae have a gradual onset and lower severity
What is the symptom presentation of elderly patients with CAP?
Classic symptoms may be absent
*More likely to have decreased functional status, weakness, mental status changes
What are the common vitals of someone with CAP?
Febrile
Tachycardic
Hypotensive
Tachypnea (rapid breathing)
What diagnostic tests may we run on a patient with CAP?
Chest Radiography (Chest X-ray)
*all patients
Sputum Characteristics (Gram stain)
Blood Culture (2 sets)
Respiratory cultures are controversial, only used for severe patients
The appearance of dense lobar consolidation or infiltrates on a Chest x-ray done on a patient with CAP is suspicious for what?
Bacterial origin
The appearance of patchy, diffuse, interstitial infiltrates on a Chest X-ray done on a patient with CAP is suspicious for what?
Atypical or viral pathogens
When doing a gram stain, we only evaluate samples that have what?
> 25 PMNs
<10 epithelial cells
What kind of organism is S. pneumoniae (aka what result on a Gram stain would make us suspicious of this organism)?
Gram + Diplococci (pairs/chains)
What kind of organism is H. influenzae (aka what result on a Gram stain would make us suspicious of this organism)?
Gram - Coccobacilli
(note that Haemophilus species are the only organisms that are classified as coccobacilli)
When are respiratory cultures used in CAP?
ONLY in severe patients
-note that use is controversial because false negatives are common
What are the criteria for diagnosing Severe CAP?
Major Criteria (Need 1):
-Septic shock requiring vasopressors
-Respiratory failure requiring mechanical ventilation
Minor Criteria (Need 3 or more):
-Resp Rate >/= 30bpm
-Pa/Fl </= 250 (rare)
-Multilobar infiltrates
-Confusion/disorientation
-Uremia (BUN >/= 20)
-Leukopenia (WBC < 4000)
-Thrombocytopenia (Plt < 100,000)
-Hypothermia (<36C)
-Hypotension requiring aggressive fluids
How can getting procalcitonin levels help us in CAP?
It is a biomarker typically elevated in bacterial infections
DO NOT USE to determine if antibiotics are needed
Useful to help guide duration of therapy
What are the 2 Clinical Prediction Tools that can be used in CAP?
Pneumonia Severity Index (PSI)
CURB-65
What are the 4 supportive treatment options that can be given to CAP pts?
Humidified Oxygen
Bronchodilators
Fluids
Chest Physiotherapy
What is the treatment for Empiric Therapy: Outpatient: No Comorbidities?
Pick 1:
Amoxicillin (strep pneumo)
Doxycycline (atypical)
Azithromycin (not monotherapy)
What is the treatment for Empiric Therapy: Outpatient: With Comorbidities?
Monotherapy:
Respiratory Fluoroquinolone (Levofloxacin, Moxifloxacin)
*Combo Therapy:
Beta-Lactam + Macrolide/Doxycycline
preferred beta-lactams:
-Amox/Clav
-Cefpodoxime
-Cefuroxime
What is the treatment for Empiric Therapy: Inpatient: Non-Severe CAP: No MRSA/Pseudomonas risks
Monotherapy:
Respiratory Fluoroquinolone (Levofloxacin, Moxifloxacin)
Combo Therapy:
Beta-Lactam + Macrolide
preferred beta-lactams:
-Ampicillin/Sulbactam
-Ceftriaxone
*note that doxycycline may be used if FQ or macrolide contraindicated
What is the treatment for Empiric Therapy: Inpatient: Severe CAP: No MRSA/Pseudomonas risk factors
Combination therapy only:
Respiratory FQ + Beta-lactam
or
Beta-Lactam + Macrolide*
*beta-lactams recommended:
-Ampicillin/Sulbactam
-Ceftriaxone
*note that doxycycline may be used if FQ or macrolide contraindicated
What are the Comorbidities that need to be take into consideration for CAP outpatient empiric therapy?
Chronic Heart, Lung, or Renal disease
Diabetes
Alcoholism
Malignancy
Asplenia/Immunosuppression
What are the risk factors for MRSA?
2-14 days post-influenza
Previous MRSA respiratory infection
Previous hospitalization and use of IV abx in last 90 days
If a CAP patient needs MRSA coverage, what should we add to their regimen?
Vancomycin
or
Linezolid
What are the risk factors for Pseudomonas?
Previous Pseudomonas respiratory infection
Previous hospitalization and use of IV abx within last 90 days
If a CAP patient needs pseudomonas coverage, what should we add to their regimen?
Piperacillin/Tazobactam
or
Cefepime
or
Meropenem
What is the preferred CAP therapy for Streptococcus pneumoniae?
Pen-susc: Penicillin G; Amoxicillin
Pen-resist: Ceftriaxone, Resp FQ
What is the preferred CAP therapy for Haemophilus influenzae?
2nd/3rd gen cephalosporin
Unasyn
Augmentin
What is the preferred CAP therapy for the atypicals: Mycoplasma pneumoniae and Chlamydia pneumoniae?
Macrolide
Doxycycline
What is the preferred CAP therapy for Legionella pneumophila?
FQ
Azithromycin
What drug class is not recommended for adults with CAP?
Corticosteroids
What is the recommended duration of CAP therapy?
Need to ensure clinical stability first
Minimum of 5 days
How is aspiration pneumonia different than other forms of pneumonia?
It is not
-there is no definition to differentiate it against pneumonia
If a patient has aspiration pneumonia, what consideration should we make with their treatment?
Anaerobic coverage is NOT NEEDED (recommended against)
*unless a lung abscess or empyema (pus development in plural space) is present
In what case would both Macrolide and Fluoroquinolone therapy for a CAP patient be contraindicated, pushing the use of Doxycycline instead?
Prolonged QTc interval (>460 ish)
What is the definition of hospital acquired pneumonia (HAP)?
Pneumonia occurring >/= 48 hours after hospital admission
What is the definition of ventilator associated pneumonia (VAP)?
Pneumonia occurring >/= 48 hours after endotracheal intubation
What are the common pathogens in HAP/VAP?
Aerobic Gram - Bacilli
-Pseudomonas
Acinetobacter baumannii
Staphylococcus aureus
*MRSA is a greater concern in this population
What testing should be conducted in HAP/VAP patients?
Respiratory Cultures*
-all patients
-note that this is different from CAP
Blood cultures
-all patients
In a respiratory culture for HAP, how many organisms need to be present for it to be considered an infection?
10,000
(>/= 10^3)
What is the risk factor for developing multi-drug resistant HAP?
Prior IV antibiotic use within 90 days
What are the risk factors for developing multi-drug resistant 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 onset
> /= 5 days of hospitalization prior to diagnosis
What is the risk factor for MRSA and Pseudomonas with HAP/VAP?
Prior IV antibiotic use within 90 days
If a HAP/VAP patient has Pseudomonas, what treatment options could they receive?
Carbapenems
Broad-spectrum beta-lactams
Fluoroquinolones
What are the risk factors for MRSA with HAP that requires Empiric MRSA Therapy?
Prior IV antibiotic use within 90 days
ICUs with > 10-20% MRSA isolates
Treatment where prevalence is unknown
What drug choices do we have for MRSA Empiric Therapy in HAP?
Vancomycin
Linezolid
What are the risk factors for Pseudomonas with HAP that requires Empiric Therapy?
Prior IV antibiotic use within 90 days
ICUs with >10% of isolates resistant
Treatment where resistance rates are unknown
What drug choices do we have for BOTH Pseudomonas Empiric Therapy AND Patients not at high risk for mortality (no ventilation/ no septic shock) in HAP?
Piperacillin-Tazobactam
Cefepime
Imipenem
Meropenem
Levofloxacin
(therapy is the same for both)
What drug choices do we have for treatment of High Risk for Mortality (ventilated or have septic shock) with MRSA Risk in HAP?
Pick 2 from Different Categories:
Piperacillin-Tazobactam
Cefepime
Imipenem
Meropenem
Levofloxacin
**Tobramycin/Amikacin
(note that this is the same as Pseudomonas and non-high risk except for addition of tobramycin/amikacin and you have to pick 2)
What are the therapy options for Empiric VAP Therapy?
*Note: choose 2 anti-pseudomonals is risk factors for resistance are present
Otherwise choose one:
-Piperacillin-Tazobactam
Cefepime
-Imipenem
-Meropenem
-Levofloxacin
-Tobramycin/Amikacin
What antibiotic should never be used in lower respiratory tract infections (pneumonia)?
Daptomycin
-it is inactivated by surfactants
What is the typical duration of HAP/VAP therapy?
7-day duration if clinically stable
