Pneumonia Flashcards
Most common organisms
causing pneumonia
- Streptococcus pneumoniae (~ 65%)
- Haemophilus influenzae (~ 10%)
- Mycoplasma pneumoniae, Legionella sp. and Chlamydia pneumoniae (~ 20%)
- Mycobacterium tuberculosis
- Viruses
other organism that cause pneumonia
- Staphylococcus aureus
- Gram negative bacilli – Burkholderia pseudomallei (meloidosis), Klebsiella pneumoniae
- Anaerobic bacteria – Peptococcus, Peptostreptococcus a. Cause aspiration pneumonia
Risk factor for
CAP
A. Host factors
- Increasing age
- Male sex
B. Modifiable risk factors
- Smoking
- Malnutrition
- Low vitamin D level
C. Underlying lung disease
- COPD, asthma
- Preceding viral respiratory infection
D. Chronic medical conditions
- Stroke
- Diabetes
- Renal disease
- Dysphagia
E. Immune suppression 1. TNFα inhibitors
2. HIV infection
F. Medications
- PPI’s
- Inhaled steroids
G. Socioeconomic factors
- Low-income household
- Crowded living conditions
Clinical presentation CAP
A. Usual presentation 1. Fever
2. Cough – productive 3. Shortness of breath 4. Tachypnea
Non-specific
- N/V/HA
- myalgia
B. Clinical signs and symptoms cannot reliably be used to predict the microbial etiology of community-acquired pneumonia.
C. Physical examination findings - Lungs
- Decreased breath sounds
- Inspiratory crackles 3. Dullness on percussion
D. Elderly and patients with co-existing illnesses may not present with usual signs and symptoms
- May present with poor feeding, drowsiness, no fever
Diagnosis of CAP
A. Clinical presentation
B. Chest X-ray
1. Changes that may indicate pneumonia – consolidation, infiltrate 2. Assess pre-existing lung disease
3. Baseline assessment – monitor response to therapy
C. White blood cell count
1. Aid in the diagnosis of infection, in general
D. Other
1. Electrolytes
2. Renal function
3. C-reactive protein (CRP) – Not specific for infection
4. Procalcitonin
- Released in response to bacterial toxins and inflammatory mediators - Aids in differential diagnosis of viral vs. bacterial infection
- Non-ICU patients
> 0.25mcg/L or ICU patients > 0.5mcg/L → can aid in decision to start antibiotic therapy
E. Microbiologic
- Aid selection of antibiotic therapy
a. Use drug active against organism
b. Narrow down spectrum of drug
c. Use lower cost drug - Identify unusual pathogens
- Gram stain sputum
a. Sputum vs. saliva
i. < 10 epithelial cells
ii. > 25 neutrophils
b. Technique and operator dependent - Sputum culture
a. Takes at least 48 – 72 hours to get results
Diagnosis
- Blood culture
a. Bacteremia in ~ 11% of patients
b. Infection can spread from blood to lungs, or lungs to blood
c. Associated with higher mortality
d. Selected hospitalized patients
i. severe pneumonia
ii. immunocompromised - Urine culture
Diagnosis
- Blood culture
a. Bacteremia in ~ 11% of patients
b. Infection can spread from blood to lungs, or lungs to blood
c. Associated with higher mortality
d. Selected hospitalized patients
i. severe pneumonia
ii. immunocompromised - Urine culture
Diagnosis
- Urine antigen tests (hard to grow on culture)
a. Legionella, Strep. pneumoniae
b. Only indicates that there has been exposure to the organism and an immunologic response - Polymerase chain reaction (PCR) assays (blood)
a. Selected organisms - Legionella, Mycoplasma, Strep. pneumoniae, Chlamydia and Viruses
b. Higher sensitivity and specificity compared to urine antigen tests
Diagnosis
- Urine antigen tests
(hard to grow on culture)
a. Legionella, Strep. pneumoniae
b. Only indicates that there has been exposure to the organism and an immunologic response - Polymerase chain reaction (PCR) assays (blood)
a. Selected organisms - Legionella, Mycoplasma, Strep. pneumoniae, Chlamydia and Viruses
b. Higher sensitivity and specificity compared to urine antigen tests
F. Guidelines on CAP are conflicting for recommendations on extent and importance of diagnostic work-up
1. Performing diagnostic tests should never delay the start of antibiotic therapy
F. Guidelines on CAP are conflicting for recommendations on extent and importance of diagnostic work-up
1. Performing diagnostic tests should never delay the start of antibiotic therapy
Risk stratification for CAP (IN OR OUT PT tx )
1) pneumonia seerity index (PSI)
- Need lots of data
- Complicated
(Lvl 1-3 = low
lvl 4 = moderate
lvl 5 = high)
2) CURB-65 severity score.
Based on
- Confusion ( =<8
score)
- Urea >7mmol/L
- Respiratory rates >= 30/min
- BP (SBP<90mmhg; DBP<= 60mmhg)
- Age >= 65yo
Group 1
= 0/1 score
= LOW mortality
= outpatient
Group 2 = 2 score = intermediate mortality = Consider hospital supervised tx ( a: Short stay inpatient b: Hospital supervised outpatient)
Group 3
= >=3 score
= High mortality
= managed in hospital as severe pneumonia
= Asess for ICU admission especially if CURB-65 score = 4or5
3) social issue
a. Caregiver support at home
b. Likelihood of compliance with outpatient therapy and follow-up
B. Other factors to consider in choosing initial empiric antibiotic therapy
1. Adverse reactions or allergies to antibiotics 2. Co-existing illnesses
B. Other factors to consider in choosing initial empiric antibiotic therapy
1. Adverse reactions or allergies to antibiotics 2. Co-existing illnesses
Target organism outpatient PSI = I or II OR CURB-65 = 0 - 1
strep. pneumonia
Atypical organisms
Empiric therapy for CAP outpatient PSI = I or II OR CURB-65 = 0 - 1
Erythromycin
500mg PO QDS
OR 800mg BD (EES)
OR Clarithromycin 500mg PO BD OR Azithromycin 500mg PO OM OR Doxycycline 100mg PO BD
OR in sever case
Macrolide/Doxycycline
PLUS amoxicillin/clavulanate 625mg po TDS OR Ampicillin/sulbactam 750 po BD OR Cefuroxime 250-500mg po BD
Inpatient (Non-ICU) PSI = III or IV
OR
CURB-65 = 2
Target organism
Strep. pneumoniae Haemophilus influenzae Atypical organisms
Inpatient (Non-ICU) PSI = III or IV
OR
CURB-65 = 2
empiric tx
Amo/clavu IV/PO
1.2g IV q8hr
OR
Ampi/sulbactam IV/PO
1.5g IV q6hr
OR ceftriaxone 1g IV q12h OR 2g IV q24hr
PLUS Clarithromycin PO 500mg BD OR Azithromycin PO 500mg OM
OR in penicillin allergy
levofloxacin
750mg IV/PO q24hr
Inpatient (Severe pneumonia, ICU)
PSI = V
OR
CURB-65 ≥ 3
Target organism
Strep. pneumoniae Atypical organisms
Burkholderia pseudomallei
Klebsiella pneumoniae
Inpatient (Severe pneumonia, ICU)
PSI = V
OR
CURB-65 ≥ 3
empiric tx
Penicillin 4MU IV q6h
OR
amo/clavu 1.2g IV q6h
PLUS Azithromycin 500mg IV q24h PLUS Ceftazidime 2g IV q8h
OR Levofloxacin 750mg IV q24hr PLUS Ceftazidime 2g IV q8h
Respiratory fluoroquinolones, anti-pneumococcal fluoroquinolones
Not recommended as first-line treatment (local practice)
- Concerns about development of resistance with overuse
- Concerns about inappropriate use for other respiratory infections
- Use has been associated with delays in diagnosis and treatment of pulmonary TB
CAP Need for empiric coverage of atypical organisms
Legionella sp., Mycoplasma pneumoniae, Chlamydophila pneumoniae
β-lactam plus macrolide or fluoroquinolone monotherapy had better outcomes compared to β-lactam alone
CAP Early initiation of antibiotics for hospitalized patients
Early initiation of antibiotics for hospitalized patients
i. Early initiation (within 8 hours) results in better outcomes
ii. Start therapy in emergency department rather than wait until patient is on ward
duration of therapy for CAP
Traditionally = 7 – 14 days
ii. Rationale for shorter courses of therapy
- Decrease development of resistance
- Reduce costs
- Decrease adverse reactions
ii. New agents with long serum and tissue half-lives may be able to give shorter course (3 – 5 days)
iii. IDSA/ATS guidelines (2007)
- Treat for minimum of 5 days
- Should be afebrile for 48-72 hours and clinically stable before discontinuation of therapy
iv. Levofloxacin dosing - Recent guidelines specify 750mg once daily x 5 days
e. Adjunctive corticosteroid therapy CAP
i. Rationale - Inflammatory response in lungs
ii. Only studied in patients who were hospitalized due to CAP
iii. Outcomes
- May decrease need for mechanical ventilation, length of stay and time to clinical stability
- Some evidence to show decreased mortality
Monitoring response to therapy CAP
- Goals of therapy
a. Cure of infection
b. Eradication of organism - Time course of response
a. Should start to see improvement in signs and symptoms in 48 – 72 hours
b. Elderly and patients with co-existing illnesses may be slower to respond
c. Should not change antibiotics within first 72 hours
- Unless patient is deteriorating or culture results available
Monitoring parameters CAP
a. Efficacy i. Chest X-ray
- Changes are slow to resolve
– 4-6 weeks or longer - Repeat if patient deteriorates
WBC count temperature CRP Cough SOB HR
Toxicity
conversation from IV to oral
1) benefits
- discharged
- cheaper
2) Criteria for switching a. Vital signs stable for 24 hours (Afebrile)
b. Able to take oral diet and oral medications
c. Others
- WBC count decreasing
- Improvement in signs and symptoms
3) Can be discharged the same day as convert to oral
Patients who do not respond to initial therapy CAP
- Incorrect diagnosis (e.g., heart failure, pulmonary embolus)
- Correct diagnosis a. Drug-related issues
i. Compliance
ii. Drug interactions
iii. Wrong dose
iv. Wrong drug
b. Pathogen-related issues
i. Unusual pathogen
ii. Resistant organism
HAP definition
- Development of a pneumonia at least 48 hours after hospital admission
- Not incubating (present) at the time of admission
HAP Prolongs hospital stay 7 – 9 days
HAP Prolongs hospital stay 7 – 9 days
Risk Factors for HAP
A. Patient-related factors 1. Age > 70 years
- Coma or impaired consciousness
- Prolonged hospitalization
- Malnutrition
- Cigarette smoking
- Co-existing illnesses
a. COPD
b. Diabetes mellitus
c. Renal failure
i. Associated with impaired lung function and defenses
B. Infection control-related factors
- Transmission of bacteria from hands of healthcare workers to patients
- Use of contaminated respiratory care equipment
C. Intervention-related factors
- Drugs
a. Sedatives, narcotic analgesics
b. Antibiotics
c. Steroids and immunosuppressive agents - Nasogastric tubes
- Intubation/mechanical ventilation (ventilator-associated pneumonia)
HAP GRAM +ve
- Streptococcus pneumoniae
- Methicillin-sensitive Staphylococcus aureus (MSSA)
- Methicillin-resistant Staph aureus (MRSA)
HAP GRAM -ve
- Escherichia coli
- Haemophilus influenzae
- Proteus species
- Serratia marcescens 5. Enterobacter species 6. Klebsiella pneumoniae (including MDR and ESBL-producing)
- Acinetobacter species (including MDR and ESBL-producing)
- Pseudomonas aeruginosa (including MDR)
HAP
A. Up to 50% of cases do not identify an organism
B. Cannot wait to start antibiotics until culture results are available
1. Studies show that mortality can be reduced with early initiation of appropriate empiric therapy
HAP
A. Up to 50% of cases do not identify an organism
B. Cannot wait to start antibiotics until culture results are available
1. Studies show that mortality can be reduced with early initiation of appropriate empiric therapy
HAP categories of pt
- Not at high risk of mortality and no risk factors increasing likelihood of MRSA
- Not at high risk of mortality, but with risk factors increasing likelihood of MRSA
- High risk of mortality or receipt of IV antibiotics in prior 90 days
Initial empiric therapy for HAP
Not at high risk of mortality and no risk factors increasing likelihood of MRSA
Piperacilin/tazobactam
4.5g IV q6h
OR
Cefepime
1-2g IV q8hr
OR
Levofloxaccin
750mg IV q24hr
OR
imipenem
500mg IV q6hr
OR
meropenam
1g IV q8hr
Not at high risk of mortality, but with risk factors increasing likelihood of MRSA
Initial empiric therapy for HAP
Piperacilin/tazobactam
4.5g IV q6h
OR
Cefepime
1-2g IV q8hr
OR
Levofloxaccin
750mg IV q24hr
OR
imipenem
500mg IV q6hr
OR
meropenam
1g IV q8hr
OR
Ceftazidime
1-2g IV q8hr
OR
ciprofloxacin
400mg IV q8-12hr
OR
Aztreonam
1-2g IV q8h
PLUS
vancomycin
15-20mg/kg IV q8-12hr
(target trough = 15-20mg/L)
OR
linezolid
600mg IV q12h
Initial empiric therapy for HAP
High risk of mortality or receipt of IV antibiotics in prior 90 days
Piperacilin/tazobactam
4.5g IV q6h
OR
Cefepime
1-2g IV q8hr
OR
imipenem
500mg IV q6hr
OR
meropenam
1g IV q8hr
OR
Ceftazidime
1-2g IV q8hr
PLUS
ciprofloxacin
400mg IV q8-12hr
OR
Levofloxaccin
750mg IV q24hr
OR
Aztreonam
1-2g IV q8h
OR
Amikacin
7.5mg/kg IV q12hr
OR 15mg/kg IV q24hr
OR
Gentamicin
1-2mg/kg IV q8h or
5-7mg/kg IV q24h
PLUS
vancomycin
15-20mg/kg IV q8-12hr
(target trough = 15-20mg/L)
OR
linezolid
600mg IV q12h
Indications for empiric MRSA coverage
HAP
- Prior IV antibiotic use within 90 days
- Hospitalization in a unit where > 20% of Staph aureus isolates are methicillin-resistant
- Where the prevalence of MRSA is not known
Risk factors for mortality HAP
- Need for ventilatory support due to the pneumonia 2. Septic shock
Duration of therapy for HAP
a. Historically = 14-21 days
b. Optimal duration not clearly established from clinical trials
c. More recent recommendations for shorter duration (i.e., 5 – 7 days)
- Patient is responding to therapy
- No multidrug-resistant organism isolated
d. IDSA/ATS guidelines (2016) = 7 days
Monotherapy vs. Combination therapy
HAP
- Synergistic activity
- Prevent development of resistance
- Broader spectrum of coverage
- More expensive
- Increased risk of adverse effects
Combination therapy recommended
- High risk of mortality
- Receipt of IV antibiotics in prior 90 days
- Pseudomonas aeruginosa as causative organism
i. Patients in septic shock or at high risk for death
Monotherapy sufficient if
- Gram positive organism as cause of pneumonia
- Mild to moderate infection
