Community acquired pneumonia

A/Prof Peter Wark

Department of Respiratory and Sleep Medicine John Hunter Hospital

• Ms AN, 37 year old

• Previously well

• 3 day history– Sore throat– Dry cough

• Today– Left sided sharp chest pain– Felt hot and unwell, rigors

Differential diagnosis

• Pneumonia

• Bronchitis

• Asthma

• Pulmonary embolus

Epidemiology

• In US pneumonia– 6th leading cause of death– Leading cause of death from an infectious disease

• Mortality– 1-5%– Up to 40%

Identifying a pathogen

Identifying a pathogen

• In clinical practice an organism is found in only 50%• No single test is available that can identify all organisms• History, clinical findings and X-ray changes are not

diagnostic of a particular organism• ? Mixed infection, especially viral and bacterial

CAP, no history of significant chronic disease

• 20-60%, Strep Pneumoniae

• 3-37%, Mycoplasma Pneumoniae and Chlamydia Pneumoniae

• 10% cases

– Viral (exceptions influenza, adenovirus)– Staph Aureus (MSSA and MRSA)– Gram neg organisms– Legionella pneumophilia (3-10%)

CAP and co-morbid diseases• Risk is increased

– Nursing home resident– Cardiorespiratory disease (COPD, CCF)– Immunosuppression– Alcoholism– Recent antibiotic use– Age > 65 years

• Cause– more gram negative organisms or resistant pathogens– Viral (CMV, VSZ, respiratory viruses– PCP– Fungal

Severe CAP

• 20-50%, Strep Pneumoniae

• 10-30% E.Coli, K Pneumoniae, Enterobacter

• 3-10% Legionella pneumophilia (adm ICU)

• Staph Aureus – MSSA– MRSA

• Viral

• Pseudomonas Aerugniosa ?

Viral pneumonia

• PCR improves detection

• Some series, accounts for up to 24%

• Not predicted by CXR or CRP

• Pathogens– Influenza– SARS– RSV– Rhinovirus (co-pathogen 35% severe CAP)– Adenovirus

How to identify the pathogen?

Sputum

• Sensitivity 10-54%

• “good sample” and cultured quickly

• Gram stain positive (esp Pneumococcus)

• Culture best with heavy growth and correlation with gram stain

• Special culture medium for Legionella, sensitivity 10-80% (better with BAL), specificity 80%

• High false positive, especially Staph Aureus & GNB

Blood cultures

• Sensitivity 7-16%, specificity 90% (depends on organism)

• Strep Pneumoniae, – accounts for 2/3 positive blood cultures– Pneumococcal bacteraemia, 1%, mortality 19% vs 4%

hospitalised with pneumococcal pneumonia

Urinary antigens

• Detection of Strep Pneumoniae & Legionella

• Advantages– Easily available– Valid after antibiotics initiated

• Pneumococcus– Sensitivity 82%, specificity 97% (bacteraemic)

• Legionella– Sensitivity 70-80%, specificity 97%– Only L. Pneumophilia

Severity scoring

• CURB-65– Confusion (1 point)– Urea >7mmols (1)– Respiratory rate >30 (1)– BP, systolic <90 or diastolic < 60 (1)– Age >65yrs

Score Implication

0-1 Risk death <3%, OP

2-33-5

Risk death 9% hospitaliseMortality 15-40% consider ICU

PSI in adultsSexM (0 points)F (-10 points)Demographic factorsAge (1 point for each year)Nursing home resident (10 points)

Comorbid illnessesNeoplastic disease (30 points)Liver disease (20 points)Congestive heart failure (10 points)Cerebrovascular disease (10 points)Renal disease (10 points)

Physical examination findingsAltered mental status (20 points)Respiratory rate >= 30/minute (20 points)Systolic blood pressure < 90 mmHg (20 points)Temperature < 35 degrees C or >= 40 degrees C (15 points)Pulse >= 125/minute (10 points)

PSI in adults

Laboratory and radiographic findingsArterial pH < 7.35 (30 points)Blood urea nitrogen >= 30 mg/dL (11 mmol/L) (20 points)Sodium < 130 mEq/L (20 points)Glucose 14 mmol/L) (10 points)Hematocrit < 30 percent (10 points)Partial pressure of arterial oxygen < 60 mmHg or oxygen saturation < 90% (10 points)Pleural effusion (10 points)

0-50 Points: Class I 0.1% Mortality

51-70 Points: Class II 0.6% Mortality

71-90 Points: Class III 0.9% Mortality

91-130 Points: Class IV 9.3% Mortality

131-395 Points: Class V 27.0% Mortality

PSI and assessment

Assessment; co-morbidities

• Age >65yrs

• Chronic disease– COPD– CCF– Diabetes– Liver disease– Chronic renal failure

– Neoplasia• Alcoholism

• Immunosuppression

Assessment examination

• Altered mental state

• Tachypnoea (RR>30)

• Hypotension (systolic <90mmHg)

• Temperature <350C or > 40oC

• Tachycardia (125bpm)

Assessment, investigations

• Electrolytes– Na <130mmol– Glucose >14mmol

• Renal impairment (Urea >11mmol/L)

• Gas exchange and acid base– pH <7.35

– PaO2 <60mmHg

• CXR– Extent consolidation– Presence of an effusion

Ms AN

Clinical Investigations

• Age 39 years

• No co-morbidities

• Altered mental state

• BP 100/50

• Temp, 39.5

• RR, 32bpm

• HR 125

• pH 7.38

• pO2 68mmHg

• Na 135mmols

• HCT 32%

• Urea 8mmols

• BGL 8mmols

• No effusionScore 104Class 4 mortality 9.3%

Management

Empirical antibiotics • Moderate

– Penicillin 1.2g 4hrly IV +– Doxycycline or clarithromycin or azithromycin orally– If gram negative, add gentamicin for 2-3 doses (7mg/kg/d)

• Severe– Penicillin 1.2g IV 6hrly +– Gentamicin IV 2-3 doses +– Azithromycin 500mg IV

• Alternate– Ceftriaxone 1g/d or – Tazocin 4.5gm QID– Moxifloxacin 400mg IV/PO daily

Outcomes with empirical antibiotics (Asadi et al Resp Med 2012

• 2973 patients mild pneumonia

• Those who received guideline based treatment, less likely to die, 6% v 1% (OR 0.23, 0.09 to 0.59)

• Those who received macrolides (as opposed to fluroquinolones) were less likely to die.

Watching the clinical response

The usual response

• 24-72 hrs, see stability

• Day 3, – improvements in symptoms– Defervescence by day 4 (most rapid Strep

Pneumoniae)– Fall in WCC & CRP or 50% reduction PCT

• CXR– Slow to resolve (60% some abnormality at 4 weeks)

Responders 48 to 72hrs

• Switch to PO therapy– Improvement in cough and dyspnoea– Afebrile– WCC & CRP improving

• Discharge

• No need to repeat CXR now, but 4-6 weeks post discharge

Procalcitonin in CAP

• PCT >0.25 mcg/L and decision to use antibiotics reduces unnecessary antibiotic use in 2 RCTs– Improves diagnosis in those with heart failure– Cost effective in ICU

• Higher PCT predicts the presence of bacteraemia

• Increase in PCT in first 72hrs was associated with reduced survival

• Fall in PCT by 50% indicates an ability to switch to PO antibiotics

PCT and CURB-65

Progress

24-72hrsclinical response

Early clinical response

Switch to oral & discharge

Lack of clinical response

Deteriorating

RevaluateHost

Pathogen Complications

Failure to respond

Lack of response or deterioration

• Host factors– Elderly– Immunosuppressed– Bacteraemia– Chronic illness– Diabetes– Alcoholism– Second nosocomial

pneumonia

• Misdiagnosis– Pulmonary embolus– CCF– Pulmonary haemorrhage– Pulmonary vasculitis– BOOP– Acute interstitial

pneumonitis– Eosinophilic pneumonia– Hypersensitivity

pneumonitis• Local factors

– Effusion/empyema– Abscess

Called to Ms AN

• Agitated and very breathless

• P 140, BP 90/50, RR 38, T 390C

• ABGs (FiO2 0.5)

– pH 7.32

– PaO2 55mmHg

– PaCO2 30mmHg

– HCO3 16mmols

Called to see Ms AN

• Agitated and very breathless

• P 140, BP 90/50, RR 38, T 390C

• ABGs (FiO2 0.5)

– pH 7.32

– PaO2 55mmHg

– PaCO2 30mmHg

– HCO3 16mmols

The cause?

• Progression of pneumonia

• ARDS

• Bacteraemia

• Shock

Empyema

• Suspect– Persistent fever– Pleuritic chest pain– Organisms (pneumococcous, Strep Milleri, Staph Aureus)

• Clinical examination

• Image again

Empyema

Lung abscess/necrotising pneumonia

Conclusions

1. Clinical assessment– Diagnosis with CXR– Risk factors for poor outcomes– Severity assessment

2. Follow guidelines for empirical antibiotics

3. Assess response

4. Reassess if response is not typical