Pneumonia
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Pneumonia Pneumonia is defined as an acute respiratory illness associated with recently developed radiological pulmonary shadowing which may be segmental, lobar or multilobar
Predisposing factors Cigarette
smoking Upper respiratory tract infection Alcohol Corticosteroid therapy Old age Recent influenza infection Pre-existing lung disease
Pneumonias are typically classified as: Community-acquired Hospital-acquired
(nosocomial) Anaerobic pneumonias and lung abscess can occur in both settings
Community-acquired pneumonia Definition & Pathogenesis Community-acquired pneumonia begins outside of the hospital or is diagnosed within 48 hours after admission to the hospital in a patient who has not resided in a long-term care facility for 14 days or more before the onset of symptoms
Pulmonary defense mechanisms (cough reflex, mucociliary clearance system, immune responses) normally prevent the development of lower respiratory tract infections following aspiration of oropharyngeal secretions containing bacteria or inhalation of infected aerosols
Community-acquired pneumonia occurs when there is a defect in one or more of the normal host defense mechanisms or when a very large infectious inoculum or a highly virulent pathogen overwhelms the host
Normal Lung
Lobar Pneumonia Alveolar air spaces are full of PMNs as well of exsanguinated RBCs
Causative agents There is failure to identify the cause of communityacquired pneumonia in 40–60% of cases
Bacterial pathogens The most common pathogen identified in most cases of community-acquired pneumonia is S pneumoniae Other bacteria are H influenzae, Mycoplasma pneumoniae, Chlamydia pneumoniae, S aureus, Neisseria meningitidis, M catarrhalis, Klebsiella pneumoniae, other gram-negative rods, and Legionella species
Streptococcus pneumoniae
Viral
causes:
Influenza virus, respiratory syncytial virus, adenovirus, and parainfluenza virus.
Other causes: Chlamydia psittaci (psittacosis), Coxiella burnetii (Q fever), Francisella tularensis (tularemia), endemic fungi (Blastomyces, Coccidioides, Histoplasma), and sin nombre virus (hantavirus pulmonary syndrome).
Clinical Findings Symptoms
Acute or subacute onset of fever Cough with or without sputum production Dyspnea Rigors, sweats, chills Chest discomfort, pleurisy Hemoptysis Fatigue Myalgias Anorexia Headache Abdominal pain
Signs Fever or hypothermia Tachypnea Tachycardia Mild arterial oxygen desaturation Patients will appear acutely ill Chest examination is often remarkable for altered breath sounds and rales (crackles or crepitations ) Dullness to percussion may be present if a parapneumonic pleural effusion is present
Streptococcus pneumoniae : In winters, young to middle aged, rapid onset, high fever, pleuritic chest pain, rusty sputum
Mycoplasma pneumoniae and Chlamydia pneumoniae : Common in young adults not in elderly
Haemophilus influenzae : Common in elderly, rarely young
Viral pneumonias: In younger children
Legionella species: Foreign travel
Klebsiella pneumoniae: Alcohol abuse, diabetes mellitus; nosocomial
Investigation Laboratory Findings
Sputum Gram stain should be attempted in all patients with community-acquired pneumonia and that sputum culture should be obtained for all patients who require hospitalization
Sputum should be obtained before antibiotics are initiated except in a case of suspected antibiotic failure
The specimen is obtained by deep cough and should be grossly purulent
Additional testing is generally recommended for patients who require hospitalization
Pre antibiotic blood cultures (at least two sets with needle sticks at separate sites) Arterial blood gases Complete blood count with differential Chemistry panel (including serum glucose, electrolytes, urea nitrogen, creatinine, bilirubin, and liver enzymes)
Assess the severity of the disease and guide evaluation and therapy. HIV serology should be obtained from all hospitalized patients.
Imaging Chest radiography
Radiographic findings can range from patchy airspace infiltrates to lobar consolidation with air bronchograms to diffuse alveolar or interstitial infiltrates
Additional findings can include pleural effusions and cavitation
No pattern of radiographic abnormalities is pathognomonic of a specific cause of pneumonia
Clearing of pulmonary infiltrates in patients with community-acquired pneumonia can take 6 weeks or longer and is usually fastest in young patients, nonsmokers, and those with only single lobe involvement.
A: Normal Chest X-ray PA view B: Lobar Pneumonia
The chest x-ray below shows extensive consolidation affecting more than one lobe in the right lung
Viral Pneumoni a
The chest x-ray below is Haemophilus influenzae showing a typical bronchopneum onic pattern of heterogeneous localized consolidation
Special Examinations Sputum
induction is reserved for patients who cannot provide expectorated sputum samples or who may have P jiroveci or Mycobacterium tuberculosis pneumonia
Transtracheal
aspiration, fiberoptic bronchoscopy, and transthoracic needle aspiration techniques to obtain samples of lower respiratory secretions or tissues are reserved for selected patients
Thoracentesis
with pleural fluid analysis (Gram stain and cultures; glucose, LDH, and total protein levels; TLC with differential) should be performed on most patients with pleural effusions to assist in diagnosis of the etiologic agent and assess for empyema or complicated parapneumonic process
Serologic
assays, polymerase chain reaction tests, specialized culture tests, and other new diagnostic tests for organisms such as Legionella, M pneumoniae, and C pneumoniae are performed when these diagnoses are suspected
Treatment General
Measure:
Rest Smoking
cessation Oxygenation Fluid balance Antibiotic therapy Nutritional support
Oxygen Pateints
with tachypnea, hypoxemia, hypotension and acidosis require oxygen therapy Aim: PaO2 > 60mmHg Some patients require assisted ventilation
Fluid Balance Oral
fluid intake is encouraged I/V Fluid therapy needed in severely ill patients, elderly and in patients with vomiting.
Antibiotic therapy
Antimicrobial therapy should be initiated promptly after the diagnosis of pneumonia is established and appropriate specimens are obtained, especially in patients who require hospitalization
Choice of Antibiotic is guided by clinical context, severity assessment, local knowledge of antibiotic resistance pattern
Uncomplicated Community Acquired Pneumonia
Amoxicillin 500 mg 8 hourly orally
If patient is allergic to penicillin
Clarithromycin 500 mg 12-hourly orally or Erythromycin 500 mg 6-hourly orally
If staphylococcus is cultured or suspected
Flucloxacillin 1-2 g 6-hourly i.v. plus Clarithromycin 500mg 12-houly i.v.
If mycoplasma or Legionella is suspected
Clarithromycin 500 mg 12-hourly orally or i.v. or Erythromycin 500 mg 6-hourly orally or i.v. plus Rifampicin 600 mg 12 hourly i.v. in severe cases
Severe Community Acquired Pneumonia
Clarithromycin 500 mg 12-hourly i.v. or Erythromycin 500 mg 6-hourly i.v. plus
Co-amoxiclav 1.2 g 8-hourly i.v. or Ceftriaxone 1-2 g daily i.v. or Cefuroxime 1.5 g 8-hourly i.v. or Amoxicillin 1 g 6-hourly i.v. plus flucloxacillin 2 g 6-hourly i.v.
Treatment of pleuritic pain
Allows
patient to breath normally and cough efficiently Adequate analgesia Extreme caution with opioids
Physiotherapy Formal
physiotherapy not required Assisted cough needed
Complications
Para-pneumonic effusion Empyema Retention of sputum causing lobar collapse Development of thromboembolic disease Pneumothorax Suppurative pneumonia/lung abscess ARDS, Renal failure, End organ failure Ectopic abscess Hepatitis, pericarditis, myocarditis, meningoencephalitis Pyrexia due to drug hyper-sensitivity.
Prevention
Polyvalent pneumococcal vaccine Indications : Age 65 years or any chronic illness that increases the risk of communityacquired pneumonia Immunocompromised patients and those at highest risk of fatal pneumococcal infections
The influenza vaccine Administered annually to persons at risk for complications of influenza infection (age 65 years, residents of long-term care facilities, patients with pulmonary or cardiovascular disorders, patients recently hospitalized with chronic metabolic disorders) as well as health care workers and others who are able to transmit influenza to high-risk patients
Hospital-Acquired Pneumonia
Hospital-acquired pneumonia is defined as pneumonia developing more than 48 hours after admission to the hospital
Pathogenesis
Colonization of the pharynx with bacteria is the most important step in the pathogenesis of nosocomial pneumonia
Pharyngeal colonization is promoted by : Instrumentation of the upper airway with nasogastric and endotracheal tubes Treatment with broad-spectrum antibiotics that promote the emergence of drug-resistant organisms Malnutrition Advanced age Altered consciousness Swallowing disorders Underlying pulmonary and systemic diseases
1. 2. 3. 4. 5. 6. 7.
Aspiration of infected pharyngeal or gastric secretions delivers bacteria directly to the lower airway
Impaired cellular and mechanical defense mechanisms in the lungs of hospitalized patients raise the risk of infection after aspiration has occurred
Tracheal intubation increases the risk of lower respiratory infection by mechanical obstruction of the trachea, impairment of mucociliary clearance, trauma to the mucociliary escalator system, and interference with coughing
Tight adherence of bacteria to the tracheal epithelium and the biofilm that lines the endotracheal tube makes clearance of these organisms from the lower airway difficult
Causative agents
The most common organisms responsible for nosocomial pneumonia are P aeruginosa, S aureus, Enterobacter, K pneumoniae, and Escherichia coli
Proteus, Serratia marcescens, H influenzae, and streptococci account for most of the remaining cases
Infection by P aeruginosa and Acinetobacter tend to cause pneumonia in the most debilitated patients, those with previous antibiotic therapy, and those requiring mechanical ventilation
Anaerobic organisms (bacteroides, anaerobic streptococci, fusobacterium) may also cause pneumonia in the hospitalized patient
Staphylococcal Pneumonia Posteroanterior chest radiograph demonstrating right upper lobe consolidation. Staphylococcus aureus was isolated from blood cultures.
The chest radiograph shows a right upper lobe pulmonary consolidation with central cavitation
Klebsiella species are associated with hospital-acquired pneumonias
Clinical Findings Symptoms and Signs
The signs and symptoms associated with nosocomial pneumonia are non-specific
Fever, leukocytosis, purulent sputum, and a new or progressive pulmonary infiltrate on chest radiograph are present in most patients
Other findings associated with nosocomial pneumonia include those for communityacquired pneumonia
Investigations The minimum evaluation for suspected nosocomial pneumonia includes:
Blood cultures from two different sites
Arterial blood gas or pulse oximetry determination
Blood counts and clinical chemistry tests can help define the severity of illness and identify complications
Thoracentesis for pleural fluid analysis (stains, cultures; glucose, LDH, and total protein levels; leukocyte count with differential; pH determination) should be performed in patients with pleural effusions
Gram stains and cultures of sputum are neither sensitive nor specific in the diagnosis of nosocomial pneumonia can be used to help identify antibiotic sensitivity patterns of bacteria and as a guide to therapy
If nosocomial pneumonia from Legionella pneumophila is suspected, direct fluorescent antibody staining can be performed
Sputum stains and cultures for mycobacteria and certain fungi may be diagnostic.
Radiographic Imaging
Radiographic findings are nonspecific and can range from patchy airspace infiltrates to lobar consolidation with air bronchograms to diffuse alveolar or interstitial infiltrates Additional findings can include pleural effusions and cavitation
Special Examinations Patients with ventilator-associated pneumonias may require lower respiratory tract secretions for analysis by endotracheal aspiration using a sterile suction catheter and fiberoptic bronchoscopy with bronchoalveolar lavage
Treatment Treatment
of nosocomial pneumonia, like treatment of community-acquired pneumonia, is usually empiric
Therapy
should be started as soon as pneumonia is suspected because of the high mortality rate
Initial
regimens must be broad in spectrum and tailored to the specific clinical setting
Adequate grame-negative coverage is usually obtained with:
A third generation cephalosporin (e.g. cefotaxime) plus an aminoglycoside ( e.g. gentamicin) or Meropenem or A monocyclic β-lactam ( e.g. aztreonam) plus flucloxacillin Aspiration pneumonis is teated by coamoxiclav 1.2 g 8-hourly plus metronidazole 500mg 8-hourly
Adequate oxygen therapy Fluid support Physiotherapy
Predisposing factors Cigarette
smoking Upper respiratory tract infection Alcohol Corticosteroid therapy Old age Recent influenza infection Pre-existing lung disease
Pneumonias are typically classified as: Community-acquired Hospital-acquired
(nosocomial) Anaerobic pneumonias and lung abscess can occur in both settings
Community-acquired pneumonia Definition & Pathogenesis Community-acquired pneumonia begins outside of the hospital or is diagnosed within 48 hours after admission to the hospital in a patient who has not resided in a long-term care facility for 14 days or more before the onset of symptoms
Pulmonary defense mechanisms (cough reflex, mucociliary clearance system, immune responses) normally prevent the development of lower respiratory tract infections following aspiration of oropharyngeal secretions containing bacteria or inhalation of infected aerosols
Community-acquired pneumonia occurs when there is a defect in one or more of the normal host defense mechanisms or when a very large infectious inoculum or a highly virulent pathogen overwhelms the host
Normal Lung
Lobar Pneumonia Alveolar air spaces are full of PMNs as well of exsanguinated RBCs
Causative agents There is failure to identify the cause of communityacquired pneumonia in 40–60% of cases
Bacterial pathogens The most common pathogen identified in most cases of community-acquired pneumonia is S pneumoniae Other bacteria are H influenzae, Mycoplasma pneumoniae, Chlamydia pneumoniae, S aureus, Neisseria meningitidis, M catarrhalis, Klebsiella pneumoniae, other gram-negative rods, and Legionella species
Streptococcus pneumoniae
Viral
causes:
Influenza virus, respiratory syncytial virus, adenovirus, and parainfluenza virus.
Other causes: Chlamydia psittaci (psittacosis), Coxiella burnetii (Q fever), Francisella tularensis (tularemia), endemic fungi (Blastomyces, Coccidioides, Histoplasma), and sin nombre virus (hantavirus pulmonary syndrome).
Clinical Findings Symptoms
Acute or subacute onset of fever Cough with or without sputum production Dyspnea Rigors, sweats, chills Chest discomfort, pleurisy Hemoptysis Fatigue Myalgias Anorexia Headache Abdominal pain
Signs Fever or hypothermia Tachypnea Tachycardia Mild arterial oxygen desaturation Patients will appear acutely ill Chest examination is often remarkable for altered breath sounds and rales (crackles or crepitations ) Dullness to percussion may be present if a parapneumonic pleural effusion is present
Streptococcus pneumoniae : In winters, young to middle aged, rapid onset, high fever, pleuritic chest pain, rusty sputum
Mycoplasma pneumoniae and Chlamydia pneumoniae : Common in young adults not in elderly
Haemophilus influenzae : Common in elderly, rarely young
Viral pneumonias: In younger children
Legionella species: Foreign travel
Klebsiella pneumoniae: Alcohol abuse, diabetes mellitus; nosocomial
Investigation Laboratory Findings
Sputum Gram stain should be attempted in all patients with community-acquired pneumonia and that sputum culture should be obtained for all patients who require hospitalization
Sputum should be obtained before antibiotics are initiated except in a case of suspected antibiotic failure
The specimen is obtained by deep cough and should be grossly purulent
Additional testing is generally recommended for patients who require hospitalization
Pre antibiotic blood cultures (at least two sets with needle sticks at separate sites) Arterial blood gases Complete blood count with differential Chemistry panel (including serum glucose, electrolytes, urea nitrogen, creatinine, bilirubin, and liver enzymes)
Assess the severity of the disease and guide evaluation and therapy. HIV serology should be obtained from all hospitalized patients.
Imaging Chest radiography
Radiographic findings can range from patchy airspace infiltrates to lobar consolidation with air bronchograms to diffuse alveolar or interstitial infiltrates
Additional findings can include pleural effusions and cavitation
No pattern of radiographic abnormalities is pathognomonic of a specific cause of pneumonia
Clearing of pulmonary infiltrates in patients with community-acquired pneumonia can take 6 weeks or longer and is usually fastest in young patients, nonsmokers, and those with only single lobe involvement.
A: Normal Chest X-ray PA view B: Lobar Pneumonia
The chest x-ray below shows extensive consolidation affecting more than one lobe in the right lung
Viral Pneumoni a
The chest x-ray below is Haemophilus influenzae showing a typical bronchopneum onic pattern of heterogeneous localized consolidation
Special Examinations Sputum
induction is reserved for patients who cannot provide expectorated sputum samples or who may have P jiroveci or Mycobacterium tuberculosis pneumonia
Transtracheal
aspiration, fiberoptic bronchoscopy, and transthoracic needle aspiration techniques to obtain samples of lower respiratory secretions or tissues are reserved for selected patients
Thoracentesis
with pleural fluid analysis (Gram stain and cultures; glucose, LDH, and total protein levels; TLC with differential) should be performed on most patients with pleural effusions to assist in diagnosis of the etiologic agent and assess for empyema or complicated parapneumonic process
Serologic
assays, polymerase chain reaction tests, specialized culture tests, and other new diagnostic tests for organisms such as Legionella, M pneumoniae, and C pneumoniae are performed when these diagnoses are suspected
Treatment General
Measure:
Rest Smoking
cessation Oxygenation Fluid balance Antibiotic therapy Nutritional support
Oxygen Pateints
with tachypnea, hypoxemia, hypotension and acidosis require oxygen therapy Aim: PaO2 > 60mmHg Some patients require assisted ventilation
Fluid Balance Oral
fluid intake is encouraged I/V Fluid therapy needed in severely ill patients, elderly and in patients with vomiting.
Antibiotic therapy
Antimicrobial therapy should be initiated promptly after the diagnosis of pneumonia is established and appropriate specimens are obtained, especially in patients who require hospitalization
Choice of Antibiotic is guided by clinical context, severity assessment, local knowledge of antibiotic resistance pattern
Uncomplicated Community Acquired Pneumonia
Amoxicillin 500 mg 8 hourly orally
If patient is allergic to penicillin
Clarithromycin 500 mg 12-hourly orally or Erythromycin 500 mg 6-hourly orally
If staphylococcus is cultured or suspected
Flucloxacillin 1-2 g 6-hourly i.v. plus Clarithromycin 500mg 12-houly i.v.
If mycoplasma or Legionella is suspected
Clarithromycin 500 mg 12-hourly orally or i.v. or Erythromycin 500 mg 6-hourly orally or i.v. plus Rifampicin 600 mg 12 hourly i.v. in severe cases
Severe Community Acquired Pneumonia
Clarithromycin 500 mg 12-hourly i.v. or Erythromycin 500 mg 6-hourly i.v. plus
Co-amoxiclav 1.2 g 8-hourly i.v. or Ceftriaxone 1-2 g daily i.v. or Cefuroxime 1.5 g 8-hourly i.v. or Amoxicillin 1 g 6-hourly i.v. plus flucloxacillin 2 g 6-hourly i.v.
Treatment of pleuritic pain
Allows
patient to breath normally and cough efficiently Adequate analgesia Extreme caution with opioids
Physiotherapy Formal
physiotherapy not required Assisted cough needed
Complications
Para-pneumonic effusion Empyema Retention of sputum causing lobar collapse Development of thromboembolic disease Pneumothorax Suppurative pneumonia/lung abscess ARDS, Renal failure, End organ failure Ectopic abscess Hepatitis, pericarditis, myocarditis, meningoencephalitis Pyrexia due to drug hyper-sensitivity.
Prevention
Polyvalent pneumococcal vaccine Indications : Age 65 years or any chronic illness that increases the risk of communityacquired pneumonia Immunocompromised patients and those at highest risk of fatal pneumococcal infections
The influenza vaccine Administered annually to persons at risk for complications of influenza infection (age 65 years, residents of long-term care facilities, patients with pulmonary or cardiovascular disorders, patients recently hospitalized with chronic metabolic disorders) as well as health care workers and others who are able to transmit influenza to high-risk patients
Hospital-Acquired Pneumonia
Hospital-acquired pneumonia is defined as pneumonia developing more than 48 hours after admission to the hospital
Pathogenesis
Colonization of the pharynx with bacteria is the most important step in the pathogenesis of nosocomial pneumonia
Pharyngeal colonization is promoted by : Instrumentation of the upper airway with nasogastric and endotracheal tubes Treatment with broad-spectrum antibiotics that promote the emergence of drug-resistant organisms Malnutrition Advanced age Altered consciousness Swallowing disorders Underlying pulmonary and systemic diseases
1. 2. 3. 4. 5. 6. 7.
Aspiration of infected pharyngeal or gastric secretions delivers bacteria directly to the lower airway
Impaired cellular and mechanical defense mechanisms in the lungs of hospitalized patients raise the risk of infection after aspiration has occurred
Tracheal intubation increases the risk of lower respiratory infection by mechanical obstruction of the trachea, impairment of mucociliary clearance, trauma to the mucociliary escalator system, and interference with coughing
Tight adherence of bacteria to the tracheal epithelium and the biofilm that lines the endotracheal tube makes clearance of these organisms from the lower airway difficult
Causative agents
The most common organisms responsible for nosocomial pneumonia are P aeruginosa, S aureus, Enterobacter, K pneumoniae, and Escherichia coli
Proteus, Serratia marcescens, H influenzae, and streptococci account for most of the remaining cases
Infection by P aeruginosa and Acinetobacter tend to cause pneumonia in the most debilitated patients, those with previous antibiotic therapy, and those requiring mechanical ventilation
Anaerobic organisms (bacteroides, anaerobic streptococci, fusobacterium) may also cause pneumonia in the hospitalized patient
Staphylococcal Pneumonia Posteroanterior chest radiograph demonstrating right upper lobe consolidation. Staphylococcus aureus was isolated from blood cultures.
The chest radiograph shows a right upper lobe pulmonary consolidation with central cavitation
Klebsiella species are associated with hospital-acquired pneumonias
Clinical Findings Symptoms and Signs
The signs and symptoms associated with nosocomial pneumonia are non-specific
Fever, leukocytosis, purulent sputum, and a new or progressive pulmonary infiltrate on chest radiograph are present in most patients
Other findings associated with nosocomial pneumonia include those for communityacquired pneumonia
Investigations The minimum evaluation for suspected nosocomial pneumonia includes:
Blood cultures from two different sites
Arterial blood gas or pulse oximetry determination
Blood counts and clinical chemistry tests can help define the severity of illness and identify complications
Thoracentesis for pleural fluid analysis (stains, cultures; glucose, LDH, and total protein levels; leukocyte count with differential; pH determination) should be performed in patients with pleural effusions
Gram stains and cultures of sputum are neither sensitive nor specific in the diagnosis of nosocomial pneumonia can be used to help identify antibiotic sensitivity patterns of bacteria and as a guide to therapy
If nosocomial pneumonia from Legionella pneumophila is suspected, direct fluorescent antibody staining can be performed
Sputum stains and cultures for mycobacteria and certain fungi may be diagnostic.
Radiographic Imaging
Radiographic findings are nonspecific and can range from patchy airspace infiltrates to lobar consolidation with air bronchograms to diffuse alveolar or interstitial infiltrates Additional findings can include pleural effusions and cavitation
Special Examinations Patients with ventilator-associated pneumonias may require lower respiratory tract secretions for analysis by endotracheal aspiration using a sterile suction catheter and fiberoptic bronchoscopy with bronchoalveolar lavage
Treatment Treatment
of nosocomial pneumonia, like treatment of community-acquired pneumonia, is usually empiric
Therapy
should be started as soon as pneumonia is suspected because of the high mortality rate
Initial
regimens must be broad in spectrum and tailored to the specific clinical setting
Adequate grame-negative coverage is usually obtained with:
A third generation cephalosporin (e.g. cefotaxime) plus an aminoglycoside ( e.g. gentamicin) or Meropenem or A monocyclic β-lactam ( e.g. aztreonam) plus flucloxacillin Aspiration pneumonis is teated by coamoxiclav 1.2 g 8-hourly plus metronidazole 500mg 8-hourly
Adequate oxygen therapy Fluid support Physiotherapy
