8. Lower Respiratory Tract Infections MT2 Flashcards
this refers to an acute infection of the pulmonary parenchyma acquired outside of the hospital
community-acquired pneumonia (CAP)
this refers to an acute infection of the pulmonary parenchyma acquired in the hospital settings and includes both hospital acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP)
nosocomial pneumonia
this type of nosocomial pneumonia refers to pneumonia acquired >48 hours after hospital admission
HAP
this type of nosocomial pneumonia refers to pneumonia acquired > 48 hours after endotracheal intubation
VAP
this is caused by “atypical” bacteria pathogens including Legionella spp., M. pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci and Coxiella burnetii
atypical pneumonia
this results from entry of gastric or oropharyngeal fluid, which may contain bacteria and/or be of low pH, or exogenous substances (e.g. ingested food particles or liquids, mineral oil, salt or fresh water) into the lower airways
aspiration pneumonia
this is the aspiration of substances (e.g. acidic gastric fluid) that causes an inflammatory reaction in the lower airways, independent of bacterial infection
chemical pneumonitis
this is an active infection caused by inoculation of large amounts of bacteria into the lungs via orogastric contents
bacterial aspiration pneumonia
this is an infection of the pleural space, usually involving anaerobes, S. aureus and/or GNB
empyema
this is part of the lungs that transfers oxygen and carbon dioxide between the air and the blood
lung parenchyma
what are some common symptoms of lower respiratory tract infections
- fever or hypothermia
- rigours
- sweats
- new cough and/or sputum production, or change in sputum color in patients with COPD
- dyspnea, tachypnea, pleuritic chest pain, tachycardia
- altered mental status (particularly in the elderly)
- nonspecific: fatigue, myalgias, abdominal pain, anorexia, headache
what are the risk factors for community-acquired pneumonia (CAP)
- > 65
- ineffective cough
- smoking
- thick mucus
- comorbities (e.g. COPD)
- lifestyle factors (crowded living conditions, living in low-income settings, environmental toxins)
- viral respiratory infections (e.g. influenza)
- impaired alveolar macrophage function (e.g immunocompromised)
what is the most common microbe identified in CAP
streptococcus pneumoniae
others: H. influenzae, S. aureus, Klebsiella, and other GNB
virus: influenza, RSV, adenovirus, parainfluenza virus, COVID-19
true or false: bacterial pneumonia can occur around the same time as a virus, or pop up later as worsening symptoms after initial improvement of the viral infection
true
when a chest Xray is performed, is lobar/alveolar consolidation more likely with bacterial or viral pneumonia
bacterial
what are some ways to prevent CAP
vaccination
- annual vaccination for seasonal influenza is indicated for all patients
- covid vaccination
- pneumococcal vaccine is indicated for anyone over 65 or with risk factors (certain comorbidities including heart, lung and liver disease, immunocompromised, impaired splenic function)
smoking cessation
how is CAP diagnosed
- mostly based on presentation and history of present illness for outpatients
- CXR infiltrates initially, but not to confirm resolution
- sputum culture should be ordered and interpreted cautiously
- blood culture for admitted pts
- PCR for viral
- bronchoscopy may be used if pt is in ICU
what technique is used to decide whether or not a patient should be admitted for CAP
CURB-65
- confusion
- urea
- respiratory rate
- blood pressure
- age
when treating a patent with CAP, what microbe should always be covered
S. pneumoniae
when treating a patient with CAP that has other comorbidities, should you tighten or broaden the spectrum of antibiotic
broaden - poor outcomes are more likely with tx failure
if a patient with CAP has no comorbidities or risk factors for MRSA or Pseudomonas, what is the standard regimen?
Amoxicillin OR doxycycline or macroline
if a patient with CAP has comorbidities, what is the standard regimen
combination of amoxi/clav or cephalosporin with macrolide or doxycycline OR monotherapy with a respiratory fluoroquinolone (e.g. levofloxacin, moxifloxacin, or gemifloxacin)
what are some criteria used to determine whether someone has severe inpatient CAP
either one major criteria (septic shock with need for vasopressors or respiratory failure requiring mechanical ventilation) or three minor criteria (increased RR, Pa02/Fl02 ratio < 250, multiliobar infiltrates, confusion/disorientation, uremia > 20mg/dl, leukopenia, thrombocytopenia, hypothermia, hypotension requiting aggressive fluid resuscitation)
what is the standard regimen for a nonsecure inpatient CAP
beta-lactam + macrolide or respiratory fluoroquinolone
what is the standard regimen for a severe inpatient CAP
beta-lactam + macrolide or beta-lactam + fluoroquinolone
what are some strong risk factors for CAP caused by MRSA
- known MRSA colonization
- prior MRSA infection
- detection of gram-positive cocci in clusters on a good-quality sputum gram stain
what are some strong risk factors for CAP caused by Pseudomonas
- known Pseudomonas colonization
- prior pseudomonas infection
- detection of gram-negative rods on a good-quality sputum gram stain
- hospitalization with receipt of IV antibiotics in the prior 3 months
are these other risk factors for CAP caused by MRSA or Pseudomonas?
- recent hospitalization or antibiotic use
- recent influenza-like illness
- necrotizing or cavitary pneumonia
- empyema
- immunosuppression
- risk factors for colonization (ESRD, crowded living conditions, injection drug use, contact sports participation, men who have sex with men)
MRSA
are these other risk factors for CAP caused by MRSA or Pseudomonas?
- recent hospitalization or stay in a long-term care facility
- recent antibiotic use of any kind
- frequent COPD exacerbations requiring glucocorticoid and/or antibiotic use
- other structural lung diseases (eg. bronchiectasis, cystic fibrosis)
- immunosuppression
Pseudomonas
what is the duration of therapy for CAP
5-7 days. 10 days in complicated patients
what is the most significant risk factor for HAP
intubation
what are some other risk factors for HAP
- older age
- chronic lung disease
- depressed consciousness
- aspiration
- chest or upper abdominal surgery
- agents that increase gastric pH (e.g. antacids)
- reintubation or prolonged incubation
- mechanical ventilation for acute respiratory distress syndrome
- frequent ventilator circuit changes
- total opioid exposure
- multiple trauma
- paralysis
- number of central venous catheter placements and surgeries
- use of muscle relaxants or glucocorticoids
- the presence of an intracranial monitor
- malnutrition
- chronic renal failure
- anemia
- previous hospitalization
is HAP usually mono microbial or polymicrobial
polymicrobial
what are the most common HAP bacteria
staphylococcus aureus (including MRSA)
Pseudomonas
what are some other common HAP pathogens
aerobic GNB (klebsiella, e. coli, enterobacter, acintobacter)
gram-positive cocci (streptococcus spp.)
viruses
fungi (more common in immunocompromised patients)
- IV antibiotics within the past 90 days
is a risk factor for…..
MDR pseudomonas, other gram-negative bacilli and MRSA (HAP)
- structural lung disease (e.g. brochiectasis or cystic fibrosis)\
- a respiratory specimen gram stain with numerous and pre-dominant gram-negative bacilli
- colonization with OR prior isolation of MDR pseudomonas or other gram-negative bacilli
these are risk factors for…..
MDR pseudomonas and other gram-negative bacilli (HAP)
- treatment in a unit in which >20% of staphylococcus isolates are methicillin resistant
- treatment in a unit in which the prevalence of MRSA is not known
- colonization with OR prior isolation of MRSA
these are risk factors for…
MRSA (HAP)
- treatment in an ICU in which > 10% of gram-negative isolates are resistant to an agent being considered for mono therapy
- treatment in an ICU in which local antimicrobial susceptibility rates are no known
- colonization with OR prior isolation of MDR pseudomonas or other gram-negative bacilli
these are risk factors for..
MDR pseudomonas and other gram-negative bacilli (VAP)
- IV antibiotic use within the previous 90 days
- septic shock at the time of VAP
- ARDs preceding VAP
- > 5 days of hospitlization prior to the occurrence of VAP
- acute renal replacement therapy prior to VAP onset
these are risk factors for….
MDR pathogens (VAP)
- treatment in a unit which > 10 to 20% of staphylococcus aureus isolates are methicillin resistant
- treatment in a unit which the prevalence of MRSA is unknown
- colonization with OR prior isolation of MRSA
these are risk factors for….
MRSA (VAP)
how should HAP/VAP therapy be tailored once the pathogen is identified
tailor therapy to susceptibility
how should HAP/VAP therapy be tailored if the patient is clinically improving but the pathogen is not identified
discontinue empiric treatment for MRSA or MDR GNB if not grown in high-quality sputum culture in 48-72 hrs
how should HAP/VAP therapy be tailored if the patient is not improving within 72 hours
evaluate for complications, other sites of infections and alternate diagnoses (e.g. empyema, lung abscess, untreated infections elsewhere, drug-resistant pathogens, additional cultures, expand empiric coverage)
if considering switching a HAP/VAP patient from an IV to PO antibiotic, what are some requirements the patient must meet
- hemodynamically stable
- clinically improving
- able to tolerate oral medications
if considering switching a HAP/VAP patients from an IV to PO antibiotic, what are some requirements the PO medication must meet for these patients
- must be based on the pathogens susceptibility pattern (if a pathogen was not identified, it should have similar antimicrobial coverage as the IV agent)
- have good lung penetration
what is the recommended duration of treatment for HAP/VAP
7 days appears to be effective
longer than 7 days may be warranted and should be individualized for patients with severe illness, bacteremia, immunocompromised, empyema, lung abscess, etc
