Community-Acquired Pneumonia (CAP)

Introduction Pneumonia is the 6th leading cause

of death in the U.S. 90% of the deaths occur in persons

over 65 years of age. The etiology is 50% idiopathic Only 20% with specific organism in

clinical practice

Introduction According to the National Institutes of

Health: “at any given time, the noses and throats of up to 70% of healthy people contain pneumococcus” (the most common cause of bacterial pneumonia).

The paradigm for any type of pneumonia is the balance between the patient's host defenses, the virulence of the potential pathogen, and the size of the exposure to the pathogen.

Definition

Pneumonia defined as inflammation of the lung parenchyma; pneumonia is characterized by consolidation of the affected part and a filling of the alveolar air spaces with exudate, inflammatory cells, and fibrin.

Classification and categorization of bacterial pneumonia Anatomic/radiographic patterns of

pneumonia Lobar pneumonia Bronchopneumonia Interstitial pneumonia Setting of infection Community-acquired pneumonia CAP Health care–associated pneumonia HCAP Nursing home–associated pneumonia NHAP Hospital-acquired pneumonia HAP Ventilator-associated pneumonia VAP Aspiration pneumonia

Pneumonia types The 2005 ATS/IDSA guidelines distinguish the following

types of pneumonia :

Community-acquired pneumonia (CAP) is defined as an acute infection of the pulmonary parenchyma in a patient who has acquired the infection in the community.

Hospital-acquired (or nosocomial) pneumonia (HAP) is pneumonia that occurs 48 hours or more after admission and did not appear to be incubating at the time of admission.

Ventilator-associated pneumonia (VAP) is a type of HAP that develops more than 48 to 72 hours after endotracheal intubation.

Pneumonia types Healthcare-associated pneumonia (HCAP) is defined as

pneumonia that occurs in a non-hospitalized patient with extensive healthcare contact, as defined by one or more of the following:

      - Intravenous therapy, wound care, or intravenous chemotherapy within the prior 30 days

      - Residence in a nursing home or other long-term care facility

      - Hospitalization in an acute care hospital for two or more days within the prior 90 days

      - Attendance at a hospital or hemodialysis clinic within the prior 30 days

Bacterial pathogens of pneumonia

Atypical organisms: Mycoplasma pneumonia, Chlamydophila species (Chlamydophila psittaci, Chlamydophila pneumoniae) Legionella species,Coxiella burnetii , Bordetella

pertussis Gram-positive bacteria: S pneumoniae , S

aureus ,Enterococcus (Enterococcus faecalis, Enterococcus faecium) Actinomyces israelii ,Nocardia asteroides

Gram-negative bacteria: Pseudomonas aeruginosa Klebsiella pneumoniae Haemophilus influenzae Escherichia coli Moraxella catarrhalis, Acinetobacter baumannii, Francisella tularensis ,Bacillus anthracis ,Yersinia pestis

Anaerobic organisms: Klebsiella, Peptostreptococcus, Bacteroides, Fusobacterium, and Prevotella

The most common etiologies of community-acquired pneumonia (CAP), listed in descending order of

frequency are as follows :

Outpatient S pneumoniae M pneumoniae H influenzae C pneumoniae Respiratory viruses

Inpatient, non-ICU

S pneumoniae M pneumoniae C pneumoniae H influenzae Legionella species Aspiration Respiratory viruses

Inpatient, ICU S pneumoniae S aureus Legionella species Gram-negative bacilli

Frequency

Histopathology Lobar pneumonia: Four stages of

inflammatory response are classically described, as follows:

Congestion Red hepatization Gray hepatization Resolution

Mortality/Morbidity

The average length of hospital stay for a patient diagnosed with pneumonia was 5 days

Pneumonia and influenza together were the sixth-eighth leading cause of death in the United States

History / Symptoms

Chest pain, dyspnea, hemoptysis (when clearly delineated from hematemesis), decreased exercise tolerance, and abdominal pain from pleuritis are also highly indicative of a pulmonary process

Rust-colored sputum - Frequently associated with infection by S pneumoniae

Currant-jelly sputum - Frequently associated with infection by Klebsiella species

Foul-smelling or bad-tasting sputum - Often produced by anaerobic infections

History / Symptoms

Nonspecific symptoms such as rigors or shaking chills, and malaise are common.

Other nonspecific symptoms that may be seen with pneumonia include myalgias, headache, nausea, vomiting, diarrhea, and altered sensorium

Potential exposures - Travel, pets, occupation, environment

History of various exposures can be helpful in determining possible etiologies and the likelihood of bacterial pneumonia, as follows:

Exposure to contaminated air-conditioning or water systems -Legionella species

Exposure to overcrowded institutions (eg, jails, homeless shelters) -S pneumoniae, Mycobacteria, Mycoplasma, Chlamydophila

Exposure to various types of animals Cats, cattle, sheep, goats -C burnetii, B

anthracis (cattle hide) Turkeys, chickens, ducks, or other birds -C

psittaci Rabbits, rodents -F tularensis, Y pestis

Aspiration risks Patients at increased risk of aspiration

with:

Alcoholism Altered mental status Anatomic abnormalities, congenital or

acquired Dysphagia GERD Seizure disorder

Physical examination

Approximately 80 % are febrile - frequently absent in older patients

A respiratory rate above 24 breaths/minute is noted in 45 to 70 % of patients

Most sensitive sign in elderly patients Tachycardia is common

Pneumonia Approach The following 3 aspects of disease are important in the

management of pneumonia, in which diagnostic testing can play a pivotal role:

Determining the presence of pneumonia Assessing disease severity at the time of

presentation Identifying the causative agent Differentiation between community-acquired

pneumonia (CAP), health care–associated pneumonia (HCAP), hospital-acquired pneumonia (HAP), and other pulmonary pathology

Diagnosis Outpatients  Testing for a microbial diagnosis is

usually not performed in outpatients. This is appropriate since empiric treatment is almost

always successful. In one study of over 700 ambulatory patients treated for

CAP, empiric antibiotics (a macrolide or fluoroquinolone in >95 percent) were almost universally effective; only 1 percent required hospitalization due to failure of the outpatient regimen

The 2007 IDSA/ATS consensus guidelines suggest that routine tests to identify an etiology for CAP are optional for patients who do not require hospitalization

An exception is in clinical or epidemiologic settings suggesting a critical microbe is the etiologic agent, in which tests for a microbial diagnosis are important

Diagnosis Critical microbes — Some microbes are

critical to detect because they represent important epidemiologic challenges and/or serious conditions that require treatment different from standard empiric regimens. These organisms include:

Legionella species Influenza A and B Avian influenza Community-associated methicillin-resistant

Staphylococcus aureus MRSA

Diagnosis

The incidence of S. aureus in the HCAP and HAP groups were comparable (47 %) and significantly higher than in the CAP group (26 %).

The rate of MRSA infection was also higher in HCAP and HAP patients compared to CAP (27 and 23 versus 9 % for CAP).

MDR pathogens Host risk factors for infection with MDR

pathogens include : Receipt of antibiotics within the preceding

90 days Current hospitalization of ≥5 days High frequency of antibiotic resistance in

the community or in the specific hospital unit

Immunosuppressive disease and/or therapy Presence of risk factors for HCAP

Laboratory studies Diagnostic testing in patients with suspected pneumonia is driven

mostly by the possibility that the results would significantly alter empiric therapy and management decisions and whether the test is likely to have a high yield.

The following initial tests are indicated with suspected pneumonia:

Blood culture, prior to antibiotic therapy Sputum Gram stain and culture, prior to antibiotic therapy (if a

good-quality, contaminant-sparse specimen containing <10 squamous epithelial cells per low-power field can be obtained)

Sputum, serum, and/or urinary antigen test for Streptococcus pneumoniae

Sputum and/or urinary antigen test for Legionella pneumophila Endotracheal aspirate for culture in intubated patients Culture and study of pleural fluid if effusion present Immune serologies for Mycoplasma pneumoniae, Chlamydophila

pneumoniae, L pneumophila, and Coxiella burnetii - Results usually not available until several weeks after infection

Severity of Pneumonia Various systems to assess the severity of

disease and risk of death exist and are in wide use, including :

PSI/PORT (ie, Pneumonia Severity Index/Patient Outcomes Research Team score)

CURB-65 system (ie, confusion, urea of 7 mmol/L, respiratory rate of 30 breaths/min, and low systolic [90 mm Hg] or diastolic [60 mm Hg] blood pressure)

Imaging Studies

Lobar pneumonias S pneumoniae: homogenous parenchymal lobar opacities with air

bronchograms; round opacity stimulating a pulmonary mass, called round pneumonia.

K pneumoniae: lobar expansion with bulging of interlobular fissures as well as cavitations.

L pneumophila: Radiologic resolution tends to lag far behind clinical improvement (8 wk to clear).

Bronchopneumonias S aureus: Lobar enlargement with bulging of interlobular fissures can be

seen in severe cases; abscesses, cavitations (with air-fluid levels), and pneumatoceles are commonly seen; 30-50% of patients develop pleural effusions, half of which are empyemas.

P aeruginosa: usually all lobes are involved, with a predilection for the lower lobes; necrosis and cavitation occur frequently; pulmonary vasculitis can produce areas of pulmonary infarction that radiographically resembles invasive aspergillosis

H influenzae: Pleural effusion is present in approximately half of infected individuals.

Imaging Studies

Aspiration pneumonias: Gravity-dependent portions of the

lungs (affected by patient positioning)

The right lung is affected twice as often as the left lung

Chest X-ray

Procedures

Bronchoscopy with or without bronchoalveolar lavage (BAL): Lung tissue can be visually evaluated and bronchial washing specimens Nonbronchoscopic bronchoalveolar lavage, mini-BAL: BAL can be performed without the use of a bronchoscope.

Transtracheal aspiration for culture Thoracentesis: Essential procedure in patients with a

parapneumonic pleural effusion.

MORTALITY

The mortality rate ranged from: 5.1 % for combined ambulatory and

hospitalized patients 13 % in hospitalized patients 36 % in patients admitted to the ICU.

PREDICTORS OF MORTALITY

Risk factors at presentation  British Thoracic Society BTS found a 21-fold

increase in mortality in patients who had two or more of the following findings :

Blood urea nitrogen greater than 20 mg/dL (7 mmol/L)

Diastolic blood pressure less than 60 mmHg Respiratory rate above 30 per minute The presence of all three variables predicted a

nine-fold greater risk for death with 70 % sensitivity and 84 % specificity

PREDICTORS OF MORTALITY

CURB-65 score These findings plus confusion

(based upon a specific mental test or new disorientation to person, place, or time) and age greater than 65 years

Prediction rule for prognosis to determine whether a patient should be admitted to the hospital

Pneumonia Severity Index

Pneumonia Severity Index

Pneumonia Severity Index

Classes I and II - Outpatient management Class III - Admission to an observation unit or for

short hospital stay Classes IV and V - Treatment in inpatient setting

Class I is 0-50 points - 0.1% mortality Class II is 51-70 points - 0.6% mortality Class III is 71-90 points - 0.9% mortality Class IV is 91-130 points - 9.3% mortality Class V is greater than 130 points - 27% mortality

Severe CAP

Additional criteria that can help determine the need for ICU admission are the presence of 3 minor criteria that compose the definition of severe CAP.

Minor criteria are as follows: Respiratory rate greater than or equal to 30 breaths per minute Ratio of PaO2 to fraction of inspired oxygen (ie, PaO2/FiO 2 ) of

less than or equal to 250 Need for noninvasive ventilation (bilevel positive airway

pressure [BiPAP] or continuous positive airway pressure [CPAP]) Multilobar infiltrates Confusion/disorientation Uremia (BUN greater than or equal to 20 mg/dL) Leukopenia (WBC count <4000 cells/µL) Thrombocytopenia (platelet count <100,000/µL) Hypothermia (core temperature <36°C) Hypotension requiring aggressive fluid resuscitation

Medication

The goals of pharmacotherapy for bacteria pneumonia are to eradicate the infection, reduce morbidity, and prevent complications.

Treatment- CAP

The regimens chosen by the IDSA/ATS guidelines mainly rely on macrolides (with or without a beta-lactam) or newer fluoroquinolones for outpatient therapy

The guidelines promote the use of macrolides to provide coverage for both S. pneumoniae and atypical pathogens (particularly, M. pneumoniae and C. pneumoniae), which account for the majority of cases of CAP in ambulatory patients

Treatment- CAP

In studies from different regions of the world, atypical pathogens account for 20 to 30 % of cases of CAP

Recent use of macrolide antibiotics is considered a risk factor for resistant S pneumoniae

Monotherapy with a macrolide is not recommended for persons who received a macrolide antibiotic in the preceding three months.

Treatment Recommend one of the following oral

regimens for HIGH RISK patients: A respiratory fluoroquinolone Combination therapy with a beta-lactam effective

against S. pneumoniae PLUS either a macrolide or Doxycycline

Comorbidities or recent antibiotic use:  The presence of significant comorbidities (ie, chronic

obstructive pulmonary disease [COPD], liver or renal disease, cancer, diabetes, chronic heart disease, alcoholism, asplenia, or immunosuppression).

Use of antibiotics within the prior three months, increases the risk of infection with more resistant pathogens.

Treatment In previously healthy patients with no

exposure to antibiotics within the previous 90 days, use the following: 

Macrolide or doxycycline In patients with comorbidities such as chronic

disease of the heart, lung, liver, or kidneys; diabetes mellitus; alcoholism; malignancy; immunosuppression (drug- or disease-induced); or use of antimicrobials within the last 90 days, use the following:

Respiratory fluoroquinolone or beta-lactam plus macrolide

Inpatient Treatment Inpatient empiric antibiotic therapy

 Inpatient treatment of pneumonia, according to 2009 Joint Commission and the Centers for Medicare and Medicaid Services consensus guidelines, should be given within 6 hours of hospital admission (or in the emergency department if this is where the patient initially presented) and should consist of the following antibiotic regimens :

Non-ICU patients (choice of one option) Beta-lactam (IV or IM) plus macrolide (IV or PO) Antipneumococcal quinolone monotherapy (IV or IM)  Beta-lactam (IV or IM) plus doxycycline (IV or oral) If patient younger than 65 years with no risk factors for drug-resistant

pneumococcus - Macrolide monotherapy (IV or oral) ICU Patients (choice of one option)

Beta-lactam (IV) plus macrolide (IV) Beta-lactam (IV) plus antipneumococcal quinolone (IV) If patient has documented beta-lactam allergy - Antipneumococcal quinolone

(IV) plus aztreonam (IV)

Inpatient Treatment Patients at increased risk of infection

with Pseudomonas (acceptable for both ICU and non-ICU patients) (choice of one option)

Antipseudomonal beta-lactam (IV) plus antipseudomonal quinolone (IV; PO in non-ICU only)

Antipseudomonal beta-lactam (IV) plus aminoglycoside (IV) plus one of the following:

Macrolide (IV) Antipneumococcal quinolone (IV; PO in non-ICU only) If patient has documented beta-lactam allergy

- Aztreonam (IV) plus aminoglycoside (IV) plus antipneumococcal quinolone (IV; PO in non-ICU only)

MRSA

For suspected infection with methicillin-resistant S aureus (MRSA):

Vancomycin or linezolid may be added to the antibiotic regimen until the organism's identity and antibiotic sensitivities are known, at which point the medications can be adjusted accordingly

Aspiration pneumonia Aspiration pneumonia empiric therapy

  The causative organisms in aspiration pneumonia have

been noted to be similar to those of CAP or HCAP Patients with severe periodontal disease, putrid sputum,

or a history of alcoholism with suspected aspiration pneumonia may be at greater risk of anaerobic infection.

One of the following antibiotic regimens is suggested for such patients:

Piperacillin-tazobactam Imipenem Clindamycin or metronidazole plus a respiratory

fluoroquinolone plus ceftriaxone

Clinical response Clinical response to antibiotic therapy should

be evaluated within 48-72 hours of initiation.

With appropriate antibiotic therapy, improvement in the clinical manifestations of pneumonia should be observed in 48-72 hours.

Because of the time required for antibiotics to act, antibiotics should not be changed within the first 72 hours unless marked clinical deterioration occurs.

Clinical response

With pneumococcal pneumonia, the cough usually resolves within 8 days and crackles heard on auscultation clear within 3 weeks.

The timing of radiologic resolution of pneumococcal pneumonia varies with patient age and the presence or absence of an underlying lung disease.

The chest radiograph usually clears within 4 weeks in patients younger than 50 years without underlying pulmonary disease.

Resolution may be delayed for 12 weeks or longer in older individuals and those with underlying lung disease.

Clinical response/Failure

If patients do not improve within 72 hours, an organism that is not susceptible or is resistant to the initial empiric antibiotic regimen should be considered.

Secondary to a complication such as empyema or abscess formation.

Broadening the differential diagnosis to include noninfectious etiologies such as malignancies, inflammatory conditions, or congestive heart failure

Further Outpatient Care

Patients should have a follow-up chest radiograph in approximately 6 weeks to ensure resolution of consolidation.

Chest radiograph findings indicating nonresolution of symptoms should raise the consideration of an endobronchial obstruction as a cause of postobstructive pneumonia.

Pneumonia in Immunocompromised Pts Smokers, alcoholics, bedridden, immuno-

compromised, elderly Common still common

S. pneumo Mycoplasma

Pneumocystis Carinii Pneumonia P. jirovecii Fever, dyspnea, non-prod cough (triad 50%),

insidious onset in AIDS, acute in other immunocompromised Pts

CXR: bilateral interstitial infiltrates Steroids for hypoxia TMP-SMZ still first line

Prevention

Smoking cessation Vaccination per ACIP recommendations

Influenza Inactivated vaccine for people >50 yo, those at risk for

influenza compolications, household contacts of high-risk persons and healthcare workers

Intranasal live, attenuated vaccine: 5-49yo without chronic underlying dz

Pneumococcal Immunocompetent ≥ 65 yo, chronic illness and

immunocompromised ≤ 64 yo

Complications

Potential complications include the following:

Destruction and fibrosis/organization of lung parenchyma

Bronchiectasis Necrotizing pneumonia Empyema Pulmonary abscess Respiratory failure Acute respiratory distress syndrome ARDS Ventilator dependence Death

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