Pneumonia in hospitalized patients

Diagnostic Strategy

Dr. Mahen Kothalawala MBBS, Dip in Micro, MD, MPH(NZ), Consultant Clinical Microbiologist

Teaching Hospital KandyOffsite consultant for TH Kegalle, DGH Matale, BH Nawalapitiya and Sirimawo Bandaranayake Specialized Hospital for

Children

1. Introduction

CAP HCAP HAP VAP

In the first 48 hrs of hospital

admission

In CAP with recent contact

with health care system

Pneumonia developing

after 48 to 72 hrs after

admission

Pneumonia developing after 48 of intubation

1. Early onset2. Late onset

Pneumonia in Hospitalized patients

2.HAP/VAP Burden

Ventilator-associated pneumonia (VAP) burden

• Common in Critical Care Unit

• Estimated 8 to 20% of ICU patients

• Occur up to 27% of mechanically ventilated patients

• Pts intubated > 24hrs are 6 to 21 times more likely to develop VAP than those intubated <24hrs

Mortality

• Mortality rates– range from 20 to 50%

• Some studies >70% (when caused by Multi resistant organisms)– Attributable mortality → difficult to quantify – due

to confounders – But, VAP ↑mortality of the underlying disease by

about 30%

Morbidity of VAP

• Prolongs ICU stay,

• Prolongs mechanical ventilation, and

• ↑↑ costs of hospitalization

3. Hospital-Acquired and ICU Pneumonia - Diagnosis

HAP/VAP• “There is no doubt that the diagnosis and

management of VAP remains one of the most controversial and challenging topics in management of critically ill patients.”

(Chan C, Chest 2005;127:425 )

• The diagnosis of hospital-acquired pneumonia is complex.

Diagnostic Testing for HAP/VAP

• Diagnostic tests are ordered for two purposes:

• To define – whether a patient has pneumonia– etiologic pathogen when pneumonia is present.

Diagnosis of HAP/VAP • A. Clinical Strategy

– A radiographic infiltrate, plus the presence of at least one of the three clinical data

– Clinical pulmonary infection score (CPIS)

• B. Microbiological Strategy– Non-invasive Methods

• Blood Cultures: • Sputum Samples and Tracheal Aspirates:

– Invasive Sampling Methods • Protected Specimen Brush (PSB): • Bronchoalveolar Lavage (BAL):

• C. Usage of other inflammatory markers to support Δof HAP/VAP– CRP– Procalcitonin– sTREM 1

A. Clinical Strategy

(A1) A radiographic evidence of infiltrate, plus the presence of at least one of the three clinical data

• new onset of fever, • purulent sputum, • leukocytosis

(A2) Clinical pulmonary infection score (CPIS)

A single clinical finding VS multiple features

• Presence of radiographic infiltrate with • one clinical feature

– fever, – leucocytosis, or – change of secretions – increase in volume

or purulent • have high sensitivity but low specificity

(especially for VAP).• Combination may improve specificity

Comparison clinical criteria with PM findings

• Presence of chest infiltrates, plus two of three clinical criteria resulted – 69% sensitivity– 75% specificity

• Using three clinical variables → sensitivity declined

• One variable → decline in specificity.

A2. Clinical pulmonary infection score (CPIS)

• A Tool with 6 easily obtained variables– body temperature, – white blood cell count, – quantity and purulence of tracheal secretions,– chest radiograph, – oxygenation, and, – bacterial growth in lower respiratory tracheal

secretions

Score Day 0 Day 3 Score

Temperature, ºC³38.5º - 38.9º = 1 point ³39.0º - 36.0º = 2 points

Temperature, ºC38.5º - 38.9º = 1 point 39.0º - 36.0º = 2 points

Blood leucocytes, mm-3 <4.000 or >11.000 = 1 point 50% band forms = add 1 point

Blood leucocytes, mm-3 <4.000 or >11.000=1 point 50% band forms = add 1 point

Tracheal secretions Presence of non-purulent tracheal

secretions = 1 pointPresence of purulent tracheal secretions

= 2 points

Tracheal secretions Presence of non-purulent tracheal

secretions = 1 pointPresence of purulent tracheal

secretions = 2 points

Oxygenation: PaO2/FIO2

>240 or ARDS = 0 point< 240 and no ARDS = 2 points

Oxygenation: PaO2/FIO2

>240 or ARDS = 0 point< 240 and no ARDS = 2 points

Pulmonary radiography No infiltrate = 0 pointDiffuse or patchy infiltrate = 1 pointLocalized infiltrate= 2 points

Pulmonary radiography No infiltrate = 0 pointDiffuse or patchy infiltrate = 1 pointLocalized infiltrate= 2 points

Microbiological Data Pathogenic bacterial cultured in rare or

hight quantity or no growth = 0 point

Pathogenic bacterial cultured in moderate or heavy quantity = 1 point

Same pathogenic bacterial seen

on Gram stain = add 1 point

Microbiological Data Pathogenic bacterial cultured in rare

or hight quantity or no growth = 0 point

Pathogenic bacterial cultured in moderate or heavy quantity = 1 point

Same pathogenic bacterial seen on Gram stain = add 1 point

Table 1. Clinical Pulmonary Infection Score (CPIS)Total Day #0 = _________ Total Day #3 = _________

Clinical pulmonary infection score (CPIS)

• Score ranges from 0 to 12• > 6/12 would correlate well →

microbiologically confirmed HAP.• CPIS → used to select patients to treat safely

with short-course antibiotic.• Some have shown that the score may lack

sensitivity and specificity to establish → ΔHAP

Pitfalls of CPIS

• Observers variability• Microbiological results are often delayed (48hrs) /

Not available always

• Practical Approach – Usage with modifications

• Modifications of CPIS– Use of Gram Stain where results available in one day– Eliminate the culture report and take same cut off

Clinical Features without CXR findings

– fever, – leukocytosis, – purulent sputum, and– a positive culture of a sputum or tracheal aspirate

→ nosocomial tracheobronchitis

Nosocomial tracheo-bronchitis Vs HAP/VAP

• Former no mortality• Can progress rarely to HAP/VAP• Contribute for cost of antibiotics

B. Microbiological Strategy

• Aim – to identify the specific pathogen by culture– (B1) Non respiratory culture

• Blood• Pleural fluid

– (B2) Lower respiratory culture (From LRT)• Invasive Method

– BAL– PSB

• Non Invasive method– Tracheal secretions

Lower respiratory tract specimens

• Useful to confirm the diagnosis and

• Adjust antibiotic treatment if necessary

Non invasive Method Tracheal Aspirates:

• Gram stain and culture of TA- may provide relevant microbiological information,

• Interpret with caution - as they not distinguish colonization from distal infection/pneumonia.

• In intubated patients, as TA is obtained from

deep of lung has higher diagnostic value

(B2)Invasive Samples

• lower airways can be easily accessed by fibreoptic flexible bronchoscopy.

• samples → obtained under direct vision

• Possible contamination is less

Protected Specimen Brush (PSB):

• Threshold to discriminate colonization and infection is 103 cfu/mL

• PSB → high sensitivity (>70%) and specificity (80-90%) for infection.

• Prior antibiotic Rx ↓detection sensitivity

Bronchoalveolar Lavage (BAL): • Has appropriate Sensitivity and specificity to

Δ HAP

• Cutoff >104 cfu/mL

• *> 2% of bacteria embedded in PMN or mφ cells in centrifuged BAL fluid → have a high specificity for infection (approaching 100%)

• Antibiotic treatment readily ↓ intracellular

bacterial count.

Clinical Vs Microbiological Strategies

The Clinical Approach

• Overly (too) sensitive• Patients treated with antibiotics

when a non-infectious process is responsible for the clinical findings. Such as – congestive heart failure, – atelectasis, – pulmonary thrombo embolism, – pulmonary drug reactions, – pulmonary hemorrhage, or – ARDS

• Requires good quality X-rays

Microbiological Approach

• Requires Invasive procedures to achieve acceptable sensitivity and specificity

• Non invasive- Isolation false positive pathogens

• Negative results- highly significant as it coming below the respiratory tract

3.Supportive tests

(C1) CRP• Inflammatory mediator

• Released from the liver after stimulation by the cytokine IL-6

• Produced as a part of SIRS/Sepsis.

• Reliable marker for infection and sepsis.

• CRP may have prognostic value in HAP.– ↑ CRP after 4 days of treatment noticed in non-

survivors (marker of poor outcome)

(C2) Procalcitonin

• PCT increase in – invasive bacterial infections, – viral infections or – autoimmune diseases.

• Predict progression to severe sepsis and shock.

• been described as a prognostic marker in VAP

• ↑ levels in first week – worse outcome

(C3) Soluble Triggering Receptor Expressed on Myeloid Cells (sTREM-1):

• sTREM-1 is a mediator the acute inflammatory response

• ↑ sTREM-1 in sepsis and shock - useful to monitor

• ↑ sTREM-1 in BAL fluid noticed in VAP– Cut off of >5 pg/mL ( Sensitivity 98% and

Specificity 90%)• s-TREM-1 in alveolar samples is marker of

HAP, • Draw back – requires BAL.

Flow chart to diagnose VAP

Treatment – Ask the expert

• END