IC16 LRTI Flashcards
What are the possible LRTIs?
bronchitis
pneumonia
What is acute bronchitis?
acute cough that lasts for <3 weeks due to inflammation of the trachea & bronchi
Which pathogen is more likely to cause acute bronchitis?
virus > bacteria
How does acute bronchitis typically come about?
typically preceded by a viral URTI
How do we treat acute bronchitis?
no need treatment as it is self-limiting
When do we use antibiotics for acute bronchitis?
when the patient develops a bacterial superinfection as a complication of the acute bronchitis
How do we counsel a patient with acute bronchitis?
- the cough may last for 3 weeks
- abx is not needed as it will not help you recover from your cough faster
- see a Dr if you develop fever, SOB, chest pain, cough increases in extent/frequency, or significant cough persists >3 weeks
What is pneumonia?
infection of the alveoli due to proliferation of microbial pathogens at the alveolar level
What are the possible pathogens that can cause pneumonia?
bacteria, fungi, virus
Which pathogen is most likely to cause pneumonia?
bacteria
Describe the pathogenesis of pneumonia (how it comes about)
- bacteria enters the lower respiratory tract via 3 mechanisms
- bacteria proliferates in lower respiratory tract and alveoli
- pneumonia
Describe the various pathways that bacteria can enter our lower respiratory tract to cause pneumonia
- aspiration of oropharyngeal secretions (breathe in bacteria from your own oropharyngeal section)
- inhalation of aerosols (inhale droplets that contain the bacteria)
- hematogenous spreading (bacteremia from another distant infection site)
What are the risk factors for pneumonia?
- smoking (suppress neutrophil function + impair MCC + damage lung epithelium)
- chronic lung conditions (eg. asthma, COPD) (destroy lung tissue + creates niduses for bacteria to multiply)
- immune suppression (eg. HIV, sepsis, GC, chemotherapy)
What should we look out for when pneumonia is suspected?
- systemic symptoms
- localised symptoms
- physical exam
- CXR
- lab findings
- urinary antigen tests
What are the systemic symptoms that pneumonia presents with?
- fever
- chills
- malaise
- altered mental status in elderly
- tachycardia
- hypotension
What are the localised symptoms that pneumonia presents with?
- cough*
- chest pain
- SOB
- tachypnea (RR >22)
- hypoxia
- increased sputum production
What does the type of cough that presents with pneumonia tell us?
wet cough - due to Strep pneumoniae
dry cough - due to H influenzae
What results from the physical exam support the diagnosis of pneumonia?
- diminished breath sounds over affected area
- crackles when breathing in
What are the radiographic findings that support the diagnosis of pneumonia?
evidence of NEW infiltrates/dense consolidation in CXR
What are the general lab findings that support the diagnosis of pneumonia?
signs of systemic infection (high WBC, cRP, procalcitonin)
What is urinary antigen test for?
detect presence of strep pneumoniae/legionella pneumophilia
What do the results of the urinary antigen test tell us?
positive for strep pneumoniae/legionella pneumophilia = EXPOSURE to the bacteria
bacteria can be causing pneumonia now OR is from previous infection
When is urinary antigen test recommended for pneumonia?
- severe CAP
- hospitalized patients
What kind of cultures do we need to obtain for pneumonia?
- blood culture
- respiratory culture & gram-stain
(obtain pre-treatment)
What kind of samples should we use for respiratory culture?
lower respiratory tract sample eg. bronchoalveolar lavage (BAL)
What kind of samples should we NOT use for respiratory culture and why?
sputum culture; highly contaminated + low yield
When is pre-treatment blood and respiratory cultures indicated?
- severe CAP
- risk factors for drug resistant pathogens (MRSA & PA)
What are the types of pneumonia?
community acquired (CAP)
hospital acquired (HAP)
ventilator associated (VAP)
What are some non-pharmacological strategies to reduce the risk of contracting CAP?
- smoking cessation
- immunization (influenza, pneumococcal)
What are the possible bacteria causing CAP?
- Strep pneumoniae
- H influenzae
- Atypicals (Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophilia)
- Staph aureus
- G(-) bacilli, esp Burkholderia pseudomallei (tropical country)
- MRSA & PA based on risk factors
What are the other pathogens to consider for pneumonia?
- influenza during circulating season (april-june, dec-feb)
- COVID-19 if presents w covid symptoms
What are the tools used for risk stratification of CAP?
- Pneumonia Severity Index (PSI)
- CURB-65
- IDSA/ATS Criteria for Severe CAP
PSI:
1. How many variables does it involve?
2. How many classes of CAP does it use?
3. How/where do we treat patients of the different classes?
- 20 variables
- 5 classes (Class I-V)
- class I-II: outpatient
class III: short hospitalization/observation
class IV-V: inpatient
CURB-65:
1. How many variables does it involve?
2. What are the variables?
3. How many risk classes of CAP does it use?
4. How/where do we treat patients of the different classes?
- 5 variables
[C] Confusion
[U] urea > 7 mmol/L
[R] RR > 30
[B] BP (SBP <90 or DBP ≤60)
[65] Age ≥65 - 3 risk classes
- score 0-1: outpatient
score 2: inpatient
score 3-5: inpatient, consider ICU
(general ward –> high dependency ward –> ICU)
IDSA/ATS Criteria for Severe CAP:
What are the classifications of criteria it uses?
major & minor criteria
What are the major criteria?
- ventilation
- septic shock requiring vasoactive meds
What are the minor criteria? (8)
- RR ≥30
- PaO2/FiO2 ≤250
- multilobar infiltrates
- confusion/disorientation
- uremia (urea >7)
- leukopenia (WBC <4)
- hypothermia (core temp <36)
- hypotension requiring aggressive fluid resuscitation
What is the criteria for severe CAP according to IDSA/ATS Criteria?
at least 1 major criterion
OR
at least 3 minor criteria
What is the sequence/flow of thoughts when deciding how to treat CAP?
- consider severity of CAP & thus site of care
- what are the potential pathogens causing that severity of CAP
- what are the abx to use for empiric therapy
What are the different severities of CAP?
outpatient, no comorbs
outpatient, w comorbs
inpatient, non-severe
inpatient, severe
What are the likely bacteria causing pneumonia under the “outpatient, no comorbs” category?
Strep pneumoniae
What are the first line abx to use for empiric treatment of “outpatient, no comorbs” category of CAP?
Penicillin
- Amoxicillin 1g q8h (highest dose)
What are the alternative abx to use for empiric treatment of “outpatient, no comorbs” category of CAP in the event of severe penicillin allergy?
Respi fluoroquinolones (levo, moxi)
What are the likely bacteria causing pneumonia under the “outpatient, w comorbs” category?
- Strep pneumoniae
- H influenzae
- Atypicals
What are the first line abx to use for empiric treatment of “outpatient, w comorbs” category of CAP?
PO beta lactams + atypical coverage
BL:
- Amox/clav
- Cefuroxime
Atypical coverage:
- Macrolides (clarithro, azithro)
- Doxycycline
Why can’t amoxicillin be used for “outpatient, w comorbs” pneumonia? Why must amox-clav be used?
amoxicillin is specific for strep pneumoniae
however, H influenzae has reported resistance against amoxicillin via production of beta lactamases
therefore, for “outpatient w comorbs” category whereby H influenzae is a possible bacteria, have to use amox-clav instead to cover the possibility of H influenzae
How do we choose which atypical cover to use?
based on contraindication
QTC prolongation = avoid macrolides
esophagitis/photosensitivity = avoid tetracyclines
Which macrolide is preferred and why?
azithro > clarithro
1. OD frequency
2. less 3A4 DDI
What are the alternative abx to use for empiric treatment of “outpatient, w comorbs” category of CAP in the event of severe penicillin allergy?
Respi fluoroquinolones (levo, moxi)
What is the route of administration of antibiotics for outpatient treatment?
Oral
What are the likely bacteria causing pneumonia under the “inpatient, non-severe” category?
- Strep pneumoniae
- H Influenzae
- Atypicals
- MRSA & PA based on risk factors
What are the risk factors for MRSA for “inpatient, non-severe” pneumonia?
- Respiratory isolation of MRSA in the last 1 year
- Hospitalization/parenteral abx use in the past 90 days + positive MRSA PCR screening
What are the risk factors for PA for “inpatient, non-severe” pneumonia?
Respiratory isolation of PA in the last 1 year
What are the MRSA agents that can be used in the treatment of pneumonia?
- IV Vanco
- IV Linezolid
Why is daptomycin not used for MRSA in pneumonia?
Daptomycin is inactivated by lung surfactant
What do you do in the case of PA risk factors?
MODIFY regimen to include PA coverage (not adding extra as one of the options provided should already have PA coverage)
What are the anti-pseudomonal agents that can be used in the treatment of pneumonia?
- Pip-tazo
- Ceftazidime
- Cefepime
- Meropenem
- Levofloxacin
What are the first line abx to use for empiric treatment of “inpatient, non-severe” category of CAP?
Strep pneumoniae, H influenzae, Atypicals: Beta lactams + atypical coverage
BL:
- Amox/clav
- Cefuroxime
- Ceftriaxone
Atypical coverage:
- Macrolides
- Doxycycline
What are the alternative abx to use for empiric treatment of “inpatient, non-severe” category of CAP in the event of severe penicillin allergy?
Respi fluoroquinolones (levo, moxi)
What is the route of administration for inpatient treatment of non-severe CAP?
start w oral if patient doing well
otherwise, initiate IV and step down to oral when patient improves
What are the likely bacteria causing pneumonia under the “inpatient, severe” category?
- Strep pneumoniae
- H Influenzae
- Atypicals
- Staph aureus
- G(-) bacilli, eg. Klebsiella pneumoniae, esp Burkholderia pseudomallei
- MRSA & PA based on risk factors
What are the first line abx to use for empiric treatment of “inpatient, severe” category of CAP?
Beta lactams + atypical coverage + Burkholderia coverage
BL:
- Amox/clav
- Pen G
Atypical coverage:
- Macrolides ONLY
Burkholderia coverage:
- Ceftazidime
- Meropenem (not usually used as v broad spectrum)
What are the alternative abx to use for empiric treatment of “inpatient, severe” category of CAP?
Respi fluoroquinolone + Ceftazidime
What is the route of administration of antibiotics for the inpatient treatment of severe CAP?
parenteral
What are the antibiotics in the regimen for “inpatient, severe” CAP that can cover for PA?
- Ceftazidime
- Levofloxacin
What do the following antibiotics cover with respect to CAP?
1. Amoxicillin
2. Amox/clav
3. Pen G
4. Cefuroxime
5. Ceftriaxone
6. Ceftazidime
7. Macrolides
8. Doxycycline
amox: Strep pneumoniae
amox/clav: Strep pneumoniae + H Influenzae + anerobes
Pen G: Strep pneumoniae
Cefuroxime: Strep pneumoniae + H Influenzae
Ceftriaxone: Strep pneumoniae + H Influenzae
Ceftazidime: Burkholderia, H Influenzae, PA
Macrolides: Atypicals, H influenzae
Doxycycline: Atypicals, H Influenzae
When will we need to include strong anaerobic coverage for CAP?
if the following are detected:
- lung abscess
- empyema (accumulation of pus in pleural space)
What antibiotics should be added for anaerobic coverage if standard regimen for CAP has no anaerobic coverage?
- Metronidazole (PO/IV)
- Clindamycin (PO/IV)
*though amox/clav has anaerobic coverage, it is not specific for it. hence, cannot specifically add amox/clav just for anaerobic coverage. UNLESS amox/clav is already part of regimen, then no need to add metronidazole or clindamycin anymore
What are the treatment options for CAP if influenza is suspected?
Oseltamivir
Recap: When can we initiate oseltamivir for influenza?
within 2 days, up to 5 days for high risk patients
When do we give patients oseltamivir?
positive influenza PCR
How many days does the patient need to be on oseltamivir?
5 days
In what scenario should antibiotics for the empiric treatment of CAP be stopped?
when there is no evidence of bacterial pathogen (ie. pneumonia most likely viral)
- negative cultures
- low procalcitonin levels (<0.25 mcg)
- early clinical stability
If antibiotics for CAP should be stopped as CAP is not bacterial (-ve culture, low procalcitonin, early clinical stability), when exactly should it be stopped?
at the 2nd/3rd day
What are the medications that should NOT be used as first line/routinely used for CAP?
- respi fluoroquinolones
- corticosteroid
When do we de-escalate antibiotics for CAP?
- hemodynamically stable (stable vitals)
- improving clinically
- able to ingest oral meds (for IV-PO conversion)
How do we de-escalate antibiotics for CAP when culture results are positive for suspected pathogens?
based on AST
How do we de-escalate antibiotics for CAP in the event of no positive cultures?
- stop MRSA, PA and Burkholderia coverage in 48h if pathogen is NOT isolated + patient is improving (ie. these resistant bacteria unlikely to be present)
- IV-PO conversion within same ABX or same CLASS
- continue coverage against Strep pneumoniae, H influenzae, atypicals
How long will most patients take to achieve clinical stability?
2-3 days
What is the minimum duration of active antibiotics for CAP provided patient achieved clinical stability?
5 days
What is the minimum duration of active antibiotics for CAP for patients with suspected MRSA/PA provided patient achieved clinical stability?
7 days
What does ‘clinical stability’ mean in the context of CAP?
- vital signs become normal (HR, RR, BP, O2 sat, temp)
- can eat
- regain baseline mental status
What is the minimum duration of active antibiotics for patients with CAP due to Burkholderia or other less common pathogens (eg. MTb)?
3-6 weeks
When will longer courses of antibiotic therapy be considered for CAP?
CAP complicated with other deep-seated infections (eg. meningitis, lung abscess) [2-3 wks]
How long do we have to wait before we can escalate antibiotic therapy for CAP?
3 days
When do we repeat radiographic imaging (eg. CXR)?
if patient deteriorates clinically (to see if there is new pneumonia/existing pneumonia spread)
*do NOT repeat CXR to see improvements
What is the definition of CAP, HAP, VAP?
CAP: onset in community / <48h after admission
HAP: onset ≥48h after admission
VAP: onset ≥48h after being put on ventilator
What are the risk factors for nosocomial pneumonia (HAP, VAP)?
- patient factors
- elderly
- smoking
- comorbs (COPD, cancer, immunosuppression)
- prolonged hospitalization
- impaired consciousness (coma)
- malnutrition - infection control factors
- lack of hand hygiene compliance
- contaminated respiratory care devices - healthcare factors
- prior abx use
- sedatives
- opioid analgesics
- ventilation
- supine position (lying down)
What are some non-pharmacological methods to prevent HAP/VAP?
- practice consistent hand hygiene
- judicious use of abx & meds w sedative effects
- for VAP,
- limit duration of mechanical ventilation
- minimise duration & deep levels of sedation
- elevate head of bed by 30 deg
What are the main bacteria to empirically cover for HAP/VAP?
- PA
- Staph aureus
- Enterobacterales (Klebsiella, E Coli, Enterobacter)
What are the risk factors for MRSA in the case of nosocomial pneumonia?
- prior IV abx use within 90 days
- isolation of MRSA in the last 1 year
- hospitalized (>20% of SA are MRSA, which is all hospitals in SG)
- patient at high risk for mortality (eg. need ventilatory support due to HAP & septic shock)
When do we initiate single antipseudomonal coverage for HAP/VAP?
no/low MDRO risk
When do we initiate double antipseudomonal coverage for HAP/VAP?
- risk factors for AMR (IV abx in the past 90 days, RRT before VAP onset, isolation of PA in the past 1 year)
- > 10% of PA isolates in that hospital are resistant to monotherapy agent
- high mortality risk (eg. on ventilator)
What antipseudomonal agents can we use for SINGLE anti-PA coverage and to cover Enterobacterales?
- Pip-tazo
- Cefepime
- Ceftazidime*
- Carbapenems (imi, mero)
*ceftazidime has been shown to drive ESBL production, therefore cefepime is preferred over ceftazidime
What antibiotic class should we AVOID for single antipseudomonal therapy?
amiNOglycosides
What anti-pseudomonal agents can we add on for DOUBLE anti-PA coverage?
- Fluoroquinolones (cipro, levo)
- Aminoglycosides (amikacin)
Which fluoroquinolone is preferred for double anti-PA coverage? Why?
cipro > levo
- better to reserve levo for CAP and TB
- levo has additional G(+) coverage that is not needed in this scenario as the other single anti-PA agents alr has G(+) coverage
What anti-MRSA antibiotics can we use for nosocomial pneumonia?
IV Vanco
IV/PO Linezolid
Recap: When can we de-escalate therapy for nosocomial pneumonia?
- hemodynamically stable
- improving clinically
- can eat oral meds
How do we de-escalate therapy for nosocomial pneumonia in the event of positive cultures?
- use AST
- step down to SINGLE anti-PA coverage
How do we de-escalate therapy for nosocomial pneumonia in the event of NO positive cultures?
- step down abx and maintain coverage against PA, Enterobacterales & MSSA - UNLESS patient very sick/significant risk for MDRO, then maintain MRSA coverage
- IV-PO conversion
How long will most patients with nosocomial pneumonia take to achieve clinical stability?
2-3 days
What does “clinical stability” mean in the context of nosocomial pneumonia?
- normal vital signs
- HAP - regain baseline mental status (obv not possible for VAP..)
What is the minimum duration of active antibiotics required for nosocomial pneumonia?
7 days REGARDLESS OF PATHOGEN
When will we require longer duration of therapy for nosocomial pneumonia?
if complicated with other deep-seated infections (eg. meningitis, lung abscess)
