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Pulmonary infections (Pneumonia)

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Pulmonary infections (Pneumonia) Pneumonia can be very broadly defined as any infection in the lung Acute Pneumonias S. pneumoniae (pneumococcus) is the most common ... – PowerPoint PPT presentation

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Title: Pulmonary infections (Pneumonia)


1
Pulmonary infections (Pneumonia)
  • Pneumonia can be very broadly defined as any
    infection in the lung

2
Pulmonary infections
  • Respiratory tract infections are more frequent
    than infections of any other organ and account
    for the largest number of workdays lost in the
    general population, why?
  • The epithelium of the lung is exposed to liters
    of contaminated air
  • Nasopharyngeal flora are aspirated during sleep
  • Underlying lung diseases render the lung
    parenchyma vulnerable to virulent organism.

3
Pulmonary infections
  • Upper respiratory tract infection are common,
    caused mainly by viruses (common cold,
    pharyngitis)
  • Infection of the lung by virus, mycoplasma,
    bacteria and fungi account for enormous amount of
    morbidity and mortality.

4
Pathogenesis of pneumonia
  • Each day, the respiratory tract is exposed to
    more
  • than 10,000 liters of air containing hazardous
    dust,
  • Chemicals and microorganisms.
  • Particle gt 10 mm deposited in nose.
  • Particle 3-10 mm impacted in trachea and bronchi.
  • Particle 1-3 mm (bacteria) deposited in terminal
    airways and alveoli.
  • Smaller particles lt 1 mm may remain suspended in
    air.
  • Normal lung is free from bacteria.

5
Pathogenesis of pneumonia
  • Pneumonia can result whenever
  • defense mechanisms are impaired
  • the resistance of the host in general is lowered.

6
Pulmonary host defenses
  • Upper airways
  • Nasopharynx
  • Oropharynx

Nasal hair, turbinates, mucociliary apparatus,
IgA secretion
Saliva, sloughing of epithelium, local complement
production, interference from resident flora

7
Pulmonary host defenses
  • Upper airways
  • Conducting airways (trachea and bronchi)

Cough, epiglottic reflexes, sharp angled branches
of the airways, mucociliary apparatus,
Immunoglobulin (IgM, IgG, and IgA) secretion
8
Pulmonary host defenses
  • Upper airways
  • Conducting airways (trachea and bronchi)
  • Lower respiratory tract

Alveolar lining fluid ( surfactant,
immunoglobulin, complement and fibronectin),
Cytokines (IL-1, TNF), alveolar macrophages,
polymorphonuclear leukocyte, cell mediated
immunity
9
Pathogenesis of pneumonia
  • Impaired defense mechanisms
  • Loss or suppression of the cough reflex,
  • as a result of coma, anesthesia, neuromuscular
    disorders, drugs, or chest pain.
  • Injury to the mucociliary apparatus,
  • by either impairment of ciliary function or
    destruction of ciliated epithelium e.g. cigarette
    smoke, inhalation of hot or corrosive gases,
    viral diseases, or genetic disturbances
  • Interference with the phagocytic or bactericidal
    action of alveolar macrophages
  • by alcohol, tobacco smoke, anoxia, or oxygen
    intoxication
  • Pulmonary congestion and edema
  • Accumulation of secretions
  • e.g. cystic fibrosis and bronchial
    obstruction
  • Defect in innate immunity
  • Include neutrophil, complement, humoral and cell
    mediated immune defects

10
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11
Pathogenesis of pneumonia
  • Defects in innate immunity (including neutrophil
    and complement defects) and humoral
    immunodeficiency lead to an increased incidence
    of infections with pyogenic bacteria.
  • Cell-mediated immune defects lead to increased
    infections with intracellular microbes such as
    mycobacteria ,herpesviruses and Pneumocystis
    jiroveci.
  • Several exogenous aspects of lifestyle interfere
    with host immune defense mechanisms and
    facilitate infections.
  • Examples
  • cigarette smoke compromises mucociliary clearance
    and pulmonary macrophage activity
  • alcohol not only impairs cough and epiglottic
    reflexes, thereby increasing the risk of
    aspiration, but also interferes with neutrophil
    mobilization and chemotaxis.

12
Pathogenesis of pneumonia
  • General factors that affect resistance
  • chronic diseases
  • immunologic deficiency
  • treatment with immunosuppressive agents
  • leukopenia
  • unusually virulent infections.

13
Pathogenesis of pneumonia
  • One type of pneumonia sometimes predisposes to
    another, especially in debilitated patients.
  • Portal of entry for most pneumonias is the
    respiratory tract, hematogenous spread from one
    organ to other organs can occur.
  • Many patients with chronic diseases acquire
    terminal pneumonias while hospitalized
    (nosocomial infection).

14
Pathogenesis of pneumonia
  • Pneumonia can be acute or chronic
  • The histologic spectrum may vary from
    fibrinopurulent alveolar exudate to mononuclear
    interstitial infiltrates to granulomatous
    inflammation

15
Bacterial pneumonia
  • Bacterial invasion of lung parenchyma evoke
    exudation of fibrinpurulent fluid in the alveoli
    and solidification.
  • Classification may be made according to causative
    agent or gross anatomic distribution of the
    disease.

16
Anatomic distribution of pneumonia
  • Bronchopneumonia
  • -Represent an extension from preexisting
  • bronchitis or bronchiolitis.
  • -Extremely common tends to occur in two
  • extremes of life.
  • Lobar pneumonia
  • - Acute bacterial infection of a large
  • portion of a lobe or entire lobe.
  • -Classic lobar pneumonia is now infrequent.

17
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18
Lobar pneumonia - 90-95 are caused by
pneumococci (type 1,3,7 2) - Rare
agents K. pneumoniae staphylococci -
streptococci H. influenzae - Pseudomonas and
Proteus
  • Bronchopneumonia
  • most common agents are
  • Streptococcus pneumonea,
  • Haemophilus Influenza,
  • Pseudomonas Aeroginosa
  • coliform bacteria.

19
  • Overlap of the two patterns often occur.
  • Identification of clinical pattern is more
    important.

20
The pneumonia syndromes
  • Community-Acquired Acute Pneumonia
  • Community-Acquired Atypical Pneumonia
  • Nosocomial Pneumonia
  • Aspiration Pneumonia
  • Chronic Pneumonia
  • Pneumonia in the Immunocompromised Host

21
The pneumonia syndromes
  • Community-Acquired Acute Pneumonia
  • Community-Acquired Atypical Pneumonia
  • Nosocomial Pneumonia
  • Aspiration Pneumonia
  • Chronic Pneumonia
  • Pneumonia in the Immunocompromised Host

22
Etiology of pneumonia Community-Acquired Acute
Pneumonia
  • Bacterial
  • Can follows viral URT infection
  • Sudden onset of high fever, chills, pleuritic
    chest pain and productive cough, may be with
    hemoptysis
  • Streptococcus pneumoniae is the most common cause
    of Community-Acquired Acute Pneumonia
  • Frequently affected pt. are those with
  • Underlying chronic disease e.g. DM, COPD, and
    congestive heart failure
  • Congenital or acquired immune deficiency
  • Decreased or absent splenic function
  • Other causative organisms are
  • Haemophilus influenzae, Moraxella catarrhalis,
    Staphylococcus aureus, Legionella pneumophila,
    Enterobacteriaceae (Klebsiella pneumoniae) and
    Pseudomonas spp.

23
Staphylococcus aureus
  • S. aureus is an important cause of secondary
    bacterial pneumonia in children and healthy
    adults after viral respiratory illnesses (e.g.,
    measles in children and influenza in both
    children and adults).
  • Staphylococcal pneumonia is associated with a
    high incidence of complications, such as lung
    abscess and empyema.
  • Staphylococcal pneumonia occurring in association
    with right-sided staphylococcal endocarditis is a
    serious complication of intravenous drug abuse.
  • It is also an important cause of nosocomial
    pneumonia

24
Haemophilus influenzaeBoth
  • encapsulated and unencapsulated forms are
    important causes of community-acquired
    pneumonias.
  • The former can cause a particularly
    life-threatening form of pneumonia in children,
    often following a respiratory viral infection.
  • Adults at risk for developing infections include
    those with chronic pulmonary diseases such as
    chronic bronchitis, cystic fibrosis, and
    bronchiectasis
  • H. influenzae is the most common bacterial cause
    of acute exacerbation of COPD.

25
Pseudomonas aeruginosa
  • it is associated with infections in cystic
    fibrosis,
  • P. aeruginosa is most commonly seen in nosocomial
  • Pseudomonas pneumonia is also common in persons
    who are neutropenic, usually secondary to
    chemotherapy in victims of extensive burns and
    in those requiring mechanical ventilation.
  • P. aeruginosa has a propensity to invade blood
    vessels at the site of infection with consequent
    extrapulmonary spread

26
Morphology of pneumonia Community-Acquired Acute
Pneumonia
  • Lobar or bronchopneumonia may occur.
  • The lower lobes or the right middle lobe are most
    frequently involved.
  • Widespread fibrinosuppurative consolidation.

27
Community-Acquired Acute Pneumonia Stages of
pneumonia
  1. Congestion lobes are heavy, red and boggy
    histologically, vascular congestion can be seen
    with proteinaceous fluid, scattered neutrophils
    and many bacteria in the alveoli.
  2. Red hepatization alveolar spaces are packed
    with neutrophils, red cells, and fibrin, pleura
    fibrinous or fibrinopurulent exudate.
  3. Gray hepatization lung is dry, gray and firm
    and the fibrinous exudate persists within the
    alveoli.
  4. Resolution exudates within the alveoli are
    enzymatically digested.

28
Community-Acquired Acute Pneumonia Morphology of
pneumonia
Congestion vascular congestion can be seen with
proteinaceous fluid, scattered neutrophils and
many bacteria in the alveoli. Red hepatization
alveolar spaces are packed with neutrophils, red
cells, and fibrin, pleura fibrinous or
fibrinopurulent exudate
29
Community-Acquired Acute Pneumonia Stages of
pneumonia
Gray hepatization fibrinous exudate persists
within the alveoli.
30
Community-Acquired Acute Pneumonia Stages of
pneumonia
Resolution exudates within the alveoli are
enzymatically digested.
31
Clinical features
  • Abrupt onset of high fever, shaking chills, and
    cough productive of mucopurulent sputum
    occasional patients may have hemoptysis.
  • When fibrinosuppurative pleuritis is present, it
    is accompanied by pleuritic pain and pleural
    friction rub

32
Complications of pneumonia
  • Tissue destruction (abscess).
  • Empyema.
  • Organization of alveolar exudate solid
    fibrinous tissue.
  • Bacteremic dissemination may lead to meningitis,
    arthritis or infective endocarditis.

33
Community-Acquired Acute Pneumonia Dx Rx
  • Examination of Gram-stained sputum smear is
    helpful in diagnosis
  • Blood culture is more specific (only ve in 20
    to 30 of pt.)
  • Pneumococcal pneumonia respond to penicillin Rx

34
  • Acute Pneumonias
  • S. pneumoniae (pneumococcus) is the most common
    cause of community-acquired acute pneumonia
  • Other common causes of acute pneumonias in the
    community include
  • H. influenzae and Moraxella catarrhalis (both
    associated with acute exacerbations of COPD)
  • S. aureus (usually secondary to viral
    respiratory infections),
  • K. pneumoniae (observed in chronic alcoholics),
  • P. aeruginosa (seen in individuals with cystic
    fibrosis, in burn patients and in neutropenics),
  • L. pneumophila, seen particularly in individuals
    who have undergone organ

35
The pneumonia syndromes
  • Community-Acquired Acute Pneumonia
  • Community-Acquired Atypical Pneumonia
  • Nosocomial Pneumonia
  • Aspiration Pneumonia
  • Chronic Pneumonia
  • Pneumonia in the Immunocompromised Host

36
Community-Acquired Atypical Pneumonia Primary
atypical pneumonia
  • Pt. Usually present with flulike symptoms with
    pharyngitis evolved into laryngitis,
    trachiobronchitis and pneumonia with little
    sputum and no lung consolidation
  • Mycoplasma pneumoniae, Chlamydia spp. (C.
    pneumoniae, C. psittaci, C. trachomatis)
  • Coxiella burnetti (Q fever)
  • Viruses respiratory syncytial virus,
    parainfluenza virus (children) influenza A and B
    (adults) adenovirus and SARS virus
  • Mycoplasma pneumoniae is associated with
    production of IgM antibody ( this react with red
    cells having I antigen leading to
    hemagglutination of cooled blood)

37
Community-Acquired Atypical Pneumonia Primary
atypical pneumonia
  • Circumstances that favor extension to lower
    respiratory tract
  • malnutrition
  • Alcoholism
  • underlying debilitating disease.

38

Community-Acquired Atypical Pneumonia Primary
atypical pneumonia
  • Acute febrile respiratory disease characterized
  • by patchy inflammatory infiltration by lymphocyte
    and plasma cells
  • largely confined to the alveolar septa and
    pulmonary
  • interstitium- (Interstitial pneumonitis).

39
Community-Acquired Atypical Pneumonia Primary
atypical pneumonia
  • Gross
  • Pneumonic involvement may be patchy, or involve
    whole lobes bilaterally or unilaterally.
  • Affected areas are red-blue congested.
  • Micro
  • Predominant interstitial inflammatory reaction.
  • Alveolar septa are widened and edematous with
    mononuclear inflammatory infiltrate (and
    neutrophils in acute cases only).
  • Intra-alveolar proteinaceous material with pink
    hyaline membrane lining the alveolar walls
    (diffuse alveolar damage).

40
Community-Acquired Atypical Pneumonia Primary
atypical pneumonia
  • Clinical course
  • Extremely variable course.
  • URTI? life-threatening infection.
  • Commonly
  • - bronchopneumonia.
  • - mycoplasma lobar pneumonia.
  • Identification of the organism is difficult.
  • Treatment antibiotic.
  • Prognosis in uncomplicated pt. is good

41
Severe Acute Respiratory Syndrome (SARS)
  • first appeared in November of 2002 in China
  • Between fall of 2002 and spring of 2003, there
    were more than 8,000 cases of SARS, including 774
    deaths
  • SARS begins with a dry cough, malaise, myalgias,
    fever and chills
  • A third of patients improve and resolve the
    infection, but the rest progress to severe
    respiratory disease with shortness of breath,
    tachypnea, and pleurisy and nearly 10 of
    patients die from the illness
  • Caused by coronaviruses, however the SARS virus
    differs from previously known coronaviruses in
    that it infects the lower respiratory tract and
    spreads throughout the body.

42
Summary
  • Atypical pneumonias are characterized by
    respiratory distress out of proportion to the
    clinical and radiologic signs, and inflammation
    that is predominantly confined to alveolar septa,
    with generally clear alveoli.
  • The most common causes of atypical pneumonias
    include those caused by M. pneumoniae, viruses,
    including influenza types A and B, C. pneumoniae,
    and C. burnetti (Q fever).

43
The pneumonia syndromes
  • Community-Acquired Acute Pneumonia
  • Community-Acquired Atypical Pneumonia
  • Nosocomial Pneumonia
  • Aspiration Pneumonia
  • Chronic Pneumonia
  • Pneumonia in the Immunocompromised Host

44
Nosocomial pneumonia
  • Nosocomial Pneumonia
  • Hospital acquired Pneumonia
  • Common in pt. with sever underlying conditions
    e.g. immunosuppression, prolonged antibiotic
    therapy, intravascular catheter and pt. with
    mechanical ventlator
  • Organism include
  • Gram-negative rods belonging to
    Enterobacteriaceae (Serratia marcescens,
    Escherichia coli, Klebsiella spp.), Pseudomonas
    spp. and Staphylococcus aureus (usually
    penicillin-resistant)

45
The pneumonia syndromes
  • Community-Acquired Acute Pneumonia
  • Community-Acquired Atypical Pneumonia
  • Nosocomial Pneumonia
  • Aspiration Pneumonia
  • Chronic Pneumonia
  • Pneumonia in the Immunocompromised Host

46
Aspiration pneumonia
  • Aspiration Pneumonia
  • Occur in debilitated patients or those who
    aspirated gastric contents
  • Chemical injury due gastric acid and bacterial
    infection including
  • Anaerobic oral flora (Bacteroides, Prevotella,
    Fusobacterium, Peptostreptococcus), admixed with
    aerobic bacteria (Streptococcus pneumoniae,
    Staphylococcus aureus, Haemophilas influenzae,
    and Pseudomonas aeruginosa)
  • A necrotizing pneumonia with fulminant clinical
    course, common complication (abscess) and
    frequent cause of death.

47
The pneumonia syndromes
  • Community-Acquired Acute Pneumonia
  • Community-Acquired Atypical Pneumonia
  • Nosocomial Pneumonia
  • Aspiration Pneumonia
  • Chronic Pneumonia
  • Pneumonia in the Immunocompromised Host

48
Chronic pneumonia
  • is most often a localized lesion in an
    immunocompetent person, with or without regional
    lymph node involvement.
  • There is typically granulomatous inflammation,
  • may be due to bacteria
  • (e.g., M. tuberculosis) or
  • fungi
  • (Histoplasma capsulatum, Coccidioides immitis,
    Blastomyces )
  • In the immunocompromised, there is usually
    systemic dissemination of the causative organism,
    accompanied by widespread disease.
  • Tuberculosis is by far the most important entity
    within the spectrum of chronic pneumonias.

49
The pneumonia syndromes
  • Community-Acquired Acute Pneumonia
  • Community-Acquired Atypical Pneumonia
  • Nosocomial Pneumonia
  • Aspiration Pneumonia
  • Chronic Pneumonia
  • Pneumonia in the Immunocompromised Host

50
Pneumonia in the Immunocompromised Host
  • Cytomegalovirus
  • Pneumocystis jiroveci
  • Mycobacterium avium-intracellulare
  • Invasive aspergillosis
  • Invasive candidiasis
  • "Usual" bacterial, viral, and fungal organisms

51
Pneumocystis Pneumonia
  • P. jiroveci (formerly known as P. carinii), an
    opportunistic infectious agent long considered to
    be a protozoan, is now believed to be more
    closely related to fungi.
  • Serologic evidence indicates that virtually all
    persons are exposed to Pneumocystis during the
    first few years of life, but in most the
    infection remains latent.
  • Reactivation and clinical disease occurs almost
    exclusively in those who are immunocompromised
    (AIDS)

52
Pneumocystis Pneumonia
Microscopically, involved areas of the lung
demonstrate a characteristic intra-alveolar
foamy, pink-staining exudate with HE stains
Silver stain demonstrates cup-shaped cyst walls
within the exudate
53
Pneumocystis Pneumonia
  • Fever, dry cough, and dyspnea occur in 90 to 95
    of patients, who typically demonstrate bilateral
    perihilar and basilar infiltrates.
  • Hypoxia is frequent pulmonary function studies
    show a restrictive lung defect.
  • The most sensitive and effective methods of
    diagnosis
  • to identify the organism in bronchoalveolar
    lavage fluids or in a transbronchial biopsy
    specimen.
  • immunofluorescence antibody kits and PCR-based
    assays have also become available for use on
    clinical specimens

54
Lung abscess
  • A localized suppurative process within the
    pulmonary parenchyma
  • features tissue necrosis and marked acute
    inflammation
  • Posssile causes aerobic and anaerobic
    streptococci, Staphylococcus aureus, and many
    gram negative organisms
  • Can follow aspiration ( one abscess of Rt. lung)
  • occur as complication of pneumonia ( multiple)
  • Abscess is filled with necrotic suppurative
    debri

55
Lung abscess
Clinical Features - Prominent cough producing
copious

amount of foul- smelling purulent sputum -
Change in position evoke paroxysm of cough
- Fever malaise and clubbing of fingers
56
Chest X- ray
57
  • Chest radiograph of a patient who had
    foul-smelling and bad-tasting sputum, an almost
    diagnostic feature of anaerobic lung abscess.

58
Lung abscess
59
Lung abscess
  • Complications
  • Pleural involvement (empyema) formation
    resulting from a bronchopleural fistula
  • massive hemoptysis, spontaneous rupture into
    uninvolved lung segments
  • non-resolution of abscess cavity
  • Bacteremia could result in brain abscess and
    meningitis
  • with antibiotic therapy 75 of abscess resolve
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