Community-Acquired Pneumonia

Etiology

Common pathogens that cause CAP to vary based on the severity of CAP (i.e., requiring treatment as an outpatient or as an inpatient outside or inside the ICU) (see Table 2):

Table 2: Microbial causes of community-acquired pneumonia

Outpatient	Non-intensive care unit (ICU) Inpatient	ICU
Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus pneumonia1 Mycoplasma Mycoplasma Mycoplasma is a species of pleomorphic bacteria that lack a cell wall, which makes them difficult to target with conventional antibiotics and causes them to not gram stain well. Mycoplasma bacteria commonly target the respiratory and urogenital epithelium. Mycoplasma pneumoniae (M. pneumoniae), the causative agent of atypical or "walking" pneumonia. Mycoplasma pneumonia2 Chlamydia Chlamydia Chlamydiae are obligate intracellular gram-negative bacteria. They lack a peptidoglycan layer and are best visualized using Giemsa stain. The family of Chlamydiaceae comprises 3 pathogens that can infect humans: Chlamydia trachomatis, Chlamydia psittaci, and Chlamydia pneumoniae. Chlamydia pneumonia2 Haemophilus Haemophilus Haemophilus is a genus of Gram-negative coccobacilli, all of whose strains require at least 1 of 2 factors for growth (factor V [NAD] and factor X [heme]); therefore, it is most often isolated on chocolate agar, which can supply both factors. The pathogenic species are H. influenzae and H. ducreyi. Haemophilus pneumonia Respiratory viruses2,3	S. pneumonia M. pneumonia2 C. pneumonia2 H. pneumonia Respiratory viruses2,3 Legionella Legionella Legionella is a facultative intracellular, gram-negative bacilli. Legionella does not grow on common culture media because it requires certain supplementation (cysteine and iron). Legionella pneumophila (L. pneumophila) accounts for the majority of human infections. Legionella/Legionellosis spp.2	S. pneumonia Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus Gram-negative bacilli H. pneumonia Respiratory viruses2,3 Legionella Legionella Legionella is a facultative intracellular, gram-negative bacilli. Legionella does not grow on common culture media because it requires certain supplementation (cysteine and iron). Legionella pneumophila (L. pneumophila) accounts for the majority of human infections. Legionella/Legionellosis spp.2
Newly identified pathogens
Metapneumovirus Severe acute respiratory syndrome coronavirus Coronavirus Coronaviruses are a group of related viruses that contain positive-sense, single-stranded RNA. Coronavirus derives its name from "κορώνη korṓnē" in Greek, which translates as "crown," after the small club-shaped proteins visible as a ring around the viral envelope in electron micrographs. Coronavirus (SARS-CoV): 2003 SARS epidemic Middle East respiratory syndrome coronavirus Coronavirus Coronaviruses are a group of related viruses that contain positive-sense, single-stranded RNA. Coronavirus derives its name from "κορώνη korṓnē" in Greek, which translates as "crown," after the small club-shaped proteins visible as a ring around the viral envelope in electron micrographs. Coronavirus (MERS-CoV): 2012 MERS outbreak Community-acquired methicillin-resistant S. aureus (CA-MRSA) SARS-CoV-2: 2019-2020 COVID-19 pandemic

An anaerobic etiology is suggested only when a history of aspiration is present days to weeks before the diagnosis of pneumonia.

• Major risk factor for aspiration pneumonia: unprotected airway (e.g., alcohol/drug overdose or seizure) + significant gingivitis
• Common complications of aspiration pneumonia: abscess formation and empyema

Epidemiology

• 80% of CAP cases are treated as outpatients.
• Most common cause of death from infection in patients > 65 years
• Almost 1 out of 5 CAP inpatients are rehospitalized within 1 month.
• CAP mortality rate is highest at age extremes.

Risk factors

General

• Age > 65 years and < 2 years
• Immunosuppression
• Chronic conditions (especially cardiopulmonary diseases, asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma)
• Reduced gag reflex
• Smoking
• Institutionalization (e.g., hospital, nursing home)
• Living in crowded conditions
• Alcoholism
• Asthma
• Immunosuppression
• Institutionalization (e.g., nursing homes)
• Age ≥ 70 years (e.g., reduced gag/cough reflex)

Specific

• Pneumococcal pneumonia: dementia, seizure disorders, heart failure, cerebrovascular disease, alcoholism, smoking, COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD), HIV
• Legionella Legionella Legionella is a facultative intracellular, gram-negative bacilli. Legionella does not grow on common culture media because it requires certain supplementation (cysteine and iron). Legionella pneumophila (L. pneumophila) accounts for the majority of human infections. Legionella/Legionellosis infection: immunosuppression, diabetes, malignancy, HIV, smoking, male sex, and a recent hotel stay or ship cruise
• P. aeruginosa: structural lung diseases such as severe COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD), bronchiectasis Bronchiectasis Bronchiectasis is a chronic disease of the airways that results from permanent bronchial distortion. This results from a continuous cycle of inflammation, bronchial damage and dilation, impaired clearance of secretions, and recurrent infections. Bronchiectasis, or cystic fibrosis Cystic fibrosis Cystic fibrosis is an autosomal recessive disorder caused by mutations in the gene CFTR. The mutations lead to dysfunction of chloride channels, which results in hyperviscous mucus and the accumulation of secretions. Common presentations include chronic respiratory infections, failure to thrive, and pancreatic insufficiency. Cystic Fibrosis
• H. influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza: smoking, COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD)
• S. aureus: influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza infection
• Gram-negative bacilli (e.g., Klebsiella Klebsiella Klebsiella are encapsulated gram-negative, lactose-fermenting bacilli. They form pink colonies on MacConkey agar due to lactose fermentation. The main virulence factor is a polysaccharide capsule. Klebsiella pneumoniae is the most important pathogenic species. Klebsiella pneumonia): increased risk of aspiration such as alcohol abuse

Clinical manifestations

• Cough:
  • Productive (mucoid, purulent, or blood-tinged sputum)
  • Nonproductive (mostly with atypical pneumonias)
  • Gross hemoptysis suggests CA-MRSA
• Dyspnea (mild to severe)
• Pleuritic chest pain Chest Pain Chest pain is one of the most common and challenging complaints that may present in an inpatient and outpatient setting. The differential diagnosis of chest pain is large and includes cardiac, gastrointestinal, pulmonary, musculoskeletal, and psychiatric etiologies. Chest Pain
• Physical examination:
  • Increased respiratory rate and use of accessory muscles
  • Increased tactile fremitus and dull percussion: consolidation
  • Decreased tactile fremitus and flat percussion: pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion
  • Auscultation: crackles, bronchial sounds in the periphery, pleural friction rub
• Nonspecific symptoms: fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, palpitations, chills, night sweats, fatigue, nausea, vomiting, headache, myalgia, arthralgia
• Pneumonia in the elderly may present with confusion.
• Severe cases may present with signs of septic shock Septic shock Organ dysfunction resulting from a dysregulated systemic host response to infection separates sepsis from uncomplicated infection. Patients commonly present with fever, tachycardia, tachypnea, hypotension, and/or altered mentation. Septic shock is diagnosed during treatment when vasopressors are necessary to control hypotension. Sepsis and Septic Shock and multiorgan failure.
• Cardiovascular complications including myocardial infarction Myocardial infarction MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction and arrhythmias.

Clinical diagnosis

• Most outpatients: symptoms and signs + chest X-ray (images 1–3)
• Some patients may require lung CT to evaluate for suspected tumors, foreign bodies, cavitary lesions, etc.

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Etiologic diagnosis

• Sputum and blood cultures are recommended only in severe pneumonia or likely infection with MRSA or  Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa.
•  Polymerase chain reaction (PCR) of nasopharyngeal swabs:
  • During influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza season, testing for influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza is recommended.
  • Testing may be indicated for a specific virus during outbreaks based on local or regional health-care policies and availability of tests. For example, testing priorities for SARS-CoV-2 during the pandemic include:
    • Hospitalized patients
    • Symptomatic healthcare workers/first responders
    • Symptomatic patients who are in long-term care facilities, are ≥ 65 years old, or have comorbidities
    • Asymptomatic critical infrastructure workers, healthcare workers, or first responders
    • Symptomatic individuals who do not meet the above categories
    • Mildly symptomatic individuals in communities with high hospitalization rates for COVID-19
  • Can also detect bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview including  Legionella Legionella Legionella is a facultative intracellular, gram-negative bacilli. Legionella does not grow on common culture media because it requires certain supplementation (cysteine and iron). Legionella pneumophila (L. pneumophila) accounts for the majority of human infections. Legionella/Legionellosis species, M. pneumoniae, C. pneumoniae, and mycobacterium Mycobacterium Mycobacterium is a genus of the family Mycobacteriaceae in the phylum Actinobacteria. Mycobacteria comprise more than 150 species of facultative intracellular bacilli that are mostly obligate aerobes. Mycobacteria are responsible for multiple human infections including serious diseases, such as tuberculosis (M. tuberculosis), leprosy (M. leprae), and M. avium complex infections. Mycobacterium
• Urinary antigen test may detect Legionalla pneumophila or pneumococcus

Noninfectious differential diagnoses

• Pulmonary edema Pulmonary edema Pulmonary edema is a condition caused by excess fluid within the lung parenchyma and alveoli as a consequence of a disease process. Based on etiology, pulmonary edema is classified as cardiogenic or noncardiogenic. Patients may present with progressive dyspnea, orthopnea, cough, or respiratory failure. Pulmonary Edema: Bilateral infiltration with central predominance and abnormal ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Normal Electrocardiogram (ECG) is suggestive.
• Pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism: rarely presents with productive cough or infiltrations visible on chest X-ray
• Lung carcinoma: A history of smoking, constitutional symptoms (e.g., significant weight loss), or chronic cough may be suggestive.
• Radiation
• Hypersensitivity pneumonitis Hypersensitivity Pneumonitis Hypersensitivity pneumonitis (HP), previously called extrinsic allergic alveolitis, is an immunologically induced inflammatory disease affecting the alveoli, bronchioles, and lung parenchyma. It is caused by repeated inhalation of an inciting agent in a susceptible host that triggers first a type III (complement-mediated) hypersensitivity reaction in the acute phase and then a type IV (delayed) reaction in the subacute and chronic phases. Hypersensitivity Pneumonitis: diagnostic criteria including a compatible exposure history
• Connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue disease involving the lung: Most often, a prior diagnosis or symptoms of underlying disease is already present.

Infectious differential diagnoses

• Acute bronchitis Acute Bronchitis Acute bronchitis is an infection of the mucous membrane of the bronchi without evidence of pneumonia. Due to its pathogenesis, acute bronchitis is frequently accompanied by an upper respiratory tract infection. Cases in which the trachea is also involved are referred to as tracheobronchitis. Acute Bronchitis
• Exacerbation of COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD)
• Tuberculosis
• Lung abscess

Risk assessment

In addition to clinical judgment, a validated prediction tool is recommended to determine the need for hospitalization:

• Preferred tool: Pneumonia Severity Index (PSI) (based on a combination of patient demographics, comorbidities, physical examination findings, and laboratory and imaging studies including arterial pH, blood urea nitrogen, serum sodium and glucose, hematocrit, partial pressure of oxygen, and pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion)
  • Risk class 1 or 2 is sent home on oral antibiotics.
  • Risk class 3 may be sent home on oral antibiotics or admitted for short-term monitoring and antibiotic therapy based on home environment and follow-up.
  • Risk class 4 or 5 is hospitalized.
• Alternative tool: CURB-65 (1 point for each of the following: confusion, blood urea nitrogen ≥ 20 mg/dL, respirations ≥ 30/min, systolic blood pressure < 90 mm Hg or diastolic blood pressure < 60 mm Hg, age ≥ 65 years):
  • 0–1 (mortality rate < 1%–3%): Patient should be sent home on oral antibiotics.
  • 2 (mortality rate 7%): Patient may be sent home on oral antibiotics or admitted for short-term monitoring and antibiotic therapy based on home environment and follow-up.
  • 3–5 (mortality rate 14%–28%): Hospitalize the patient.

Severe CAP or CAP requiring ICU admission is defined by CAP plus at least 1 of the following:

• Septic shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock requiring vasopressors
• Respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure requiring mechanical ventilation
• 3 or more of the following: respirations ≥ 30/min, PaO₂/FiO₂ ≤ 250, multilobar pneumonia, confusion, blood urea nitrogen ≥ 20 mg/dL, WBC < 4,000 cells/µL, platelet < 100,000/µL, hypothermia Hypothermia Hypothermia can be defined as a drop in the core body temperature below 35°C (95°F) and is classified into mild, moderate, severe, and profound forms based on the degree of temperature decrease. Hypothermia, hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension requiring aggressive fluid management)

Management

• Serum procalcitonin levels should not influence the decision to treat pneumonia with antibiotics.
• Initial antibiotic treatment for outpatients with CAP:
  • No comorbidities or risk factors for MRSA or P. aeruginosa:
    • Amoxicillin OR
    • Doxycycline OR
    • Macrolide (azithromycin, clarithromycin)
  • With comorbidities (e.g., congestive heart disease, chronic lung disease, malignancy, cerebrovascular disease, renal disease, liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver disease):
    • Amoxicillin/clavulanate (or cephalosporin) AND macrolide (or doxycycline) OR
    • Respiratory fluoroquinolone (levofloxacin, moxifloxacin, gemifloxacin)
• Initial antibiotic treatment for inpatients with CAP:
  • Nonsevere:
    • Β-lactam and macrolide OR
    • Respiratory fluoroquinolone
    • If ≥ 2 risk factors for MRSA or P. aeruginosa are present, add coverage (see below) only if culture/PCR is positive.
    • If lung abscess or empyema is suspected, add anaerobic coverage. (Note: suspected aspiration pneumonia is not an indication for anaerobic coverage.)
  • Severe:
    • Β-lactam and macrolide (preferred) OR
    • Β-lactam and respiratory fluoroquinolone
    • If ≥ 2 risk factors for MRSA or P. aeruginosa are present, add coverage
    • If lung abscess or empyema is suspected, add anaerobic coverage. (Note: suspected aspiration pneumonia is not an indication for anaerobic coverage.)
• Empiric coverage for MRSA includes vancomycin or linezolid.
• Empiric coverage for P. aeruginosa includes piperacillin-tazobactam, cefepime, ceftazidime, aztreonam Aztreonam The carbapenems and aztreonam are both members of the bactericidal beta-lactam family of antibiotics (similar to penicillins). They work by preventing bacteria from producing their cell wall, ultimately leading to bacterial cell death. Carbapenems and Aztreonam, meropenem, or imipenem.
• Outpatients and inpatients with CAP who test positive for influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza should receive anti- influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza treatment (e.g., oseltamivir) in addition to standard therapy for CAP.
• Adjunctive measures in the treatment of CAP:
  • Hydration, oxygen therapy for hypoxemia, vasopressors for shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock, and mechanical ventilation for respiratory failure
  • Corticosteroids are only used in refractory septic shock Septic shock Organ dysfunction resulting from a dysregulated systemic host response to infection separates sepsis from uncomplicated infection. Patients commonly present with fever, tachycardia, tachypnea, hypotension, and/or altered mentation. Septic shock is diagnosed during treatment when vasopressors are necessary to control hypotension. Sepsis and Septic Shock.
• Duration of antibiotic therapy in outpatients and inpatients with CAP is at least 5 days and based on improvement of vital signs, mentation, ability to eat, and the patient’s overall clinical condition.
• Follow-up chest imaging is not routinely recommended in patients with resolution of CAP within 1 week.
• If no improvement by day 3 or progressively worsening condition despite receiving antibiotics, evaluate:
  • Noninfectious differential diagnosis
  • Infections other than pneumonia
  • Nosocomial superinfection
  • Focus such as lung abscess or empyema blocking antibiotic access to pathogen
  • Resistance to or wrong dose of antibiotic(s)
  • Presence of unsuspected pathogens such as CA-MRSA, tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis, or fungus

Complications

• General:
  • Respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure
  • Shock and multiorgan failure
  • Coagulopathy
• Specific:
  • Metastatic infection (rare) such as brain abscess Brain abscess Brain abscess is a life-threatening condition that involves the collection of pus in the brain parenchyma caused by infection from bacteria, fungi, parasites, or protozoa. The most common presentation is headache, fever with chills, seizures, and neurological deficits. Brain Abscess or left side endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis
  • Lung abscess: suggests aspiration pneumonia (mixed anaerobic-aerobic infection), CA-MRSA, or P. aeruginosa
  • Complicated pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion (pus, pH < 7, glucose < 2.2 mmol/L, lactate dehydrogenase > 1,000 U/L, or positive culture for bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview): complete drainage usually with a chest tube ± delayed video-assisted thoracoscopy
  • Relapse or recurrence in same lung segment: evaluate for underlying neoplasm

Prevention

• Vaccination Vaccination Vaccination is the administration of a substance to induce the immune system to develop protection against a disease. Unlike passive immunization, which involves the administration of pre-performed antibodies, active immunization constitutes the administration of a vaccine to stimulate the body to produce its own antibodies. Vaccination:
  • Pneumococcal vaccine Vaccine A vaccine is usually an antigenic, non-virulent form of a normally virulent microorganism. Vaccinations are a form of primary prevention and are the most effective form due to their safety, efficacy, low cost, and easy access. Vaccination (e.g., PCV13) is recommended in children, the elderly, and immunocompromised patients
  • Inactive or recombinant form of influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza vaccine Vaccine A vaccine is usually an antigenic, non-virulent form of a normally virulent microorganism. Vaccinations are a form of primary prevention and are the most effective form due to their safety, efficacy, low cost, and easy access. Vaccination is recommended.
    • During outbreaks, patients without prior immunization and at risk for complications should receive the vaccine Vaccine A vaccine is usually an antigenic, non-virulent form of a normally virulent microorganism. Vaccinations are a form of primary prevention and are the most effective form due to their safety, efficacy, low cost, and easy access. Vaccination + antiviral chemoprophylaxis (oseltamivir or zanamivir) for 2 weeks until the vaccine Vaccine A vaccine is usually an antigenic, non-virulent form of a normally virulent microorganism. Vaccinations are a form of primary prevention and are the most effective form due to their safety, efficacy, low cost, and easy access. Vaccination induces sufficient protection
• Smokers should be encouraged to quit smoking.