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
