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Nelsons > Chapter 400: Community Acquired Pneumonia > Flashcards

Chapter 400: Community Acquired Pneumonia Flashcards

1
Q

Definition of pneumonia

A

inflammation of the lung parenchyma

leading cause of death globally in children < 5 years of age.

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2
Q

Causes of pneumonia

A

1 - infectious
2 - non infectious :
1 - aspiration ( of food or gastric acid or foreign bodies, hydrocarbons and lipoid substance)
2 - hypersensitivity reaction
3 - drug or radiation induced pneumonitis

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3
Q

most common bacterial pathology in children 3 weeks to 4 years of age.

A

Streptococcus pneumoniae ( pneumococcus)

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4
Q

most common bacterial pathology in children 5 years and older

A

Mycoplasma pneumoniae and Chlamydophila pneumoniae

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5
Q

Major cause of hospitalization and death from pneumonia in children in developing countries

A

Streptococcus pneumoniae
H. Influenzae
Staphylococcus aureus

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6
Q

causes of pneumonia in children with HIV infection

A 
Mycobacterium tuberculosis
atypical mycobcteria
salmonella
Escherichia coli
pneumocystis jiroveci
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7
Q

Frequent pathogens in neonates <3 weeks

in order of frequency

A 
Group B streptococcus
Escherichia coli
Other gram negative bacilli
Streptococcus pneumoniae
Hemophilus influenzae ( type b, nontypeable)
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8
Q

Frequent pathogens in infants: 3 weeks to 3 months

in order of frequency

A

Respiratory syncytial virus
Other respiratory viruses ( rhinoviruses, parainfluenza viruses, influenza viruses, adenovirus)
Streptococcus pneumoniae
Hemophilus influenzae
If patient is afebrile consider Chlamydia trachomatis

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9
Q

Frequent pathogens in children: 4 months to 4 years

in order of frequency

A 
Respiratory syncytial virus
Other respiratory viruses ( rhinoviruses, parainfluenza viruses, influenza viruses, adenovirus)
Streptococcus pneumoniae
Hemophilus influenzae
Mycoplasma pneumoniae
Group A streptococcus
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10
Q

Frequent pathogens in children: more than 5 years

in order of frequency

A 
Mycoplasma pneumoniae
Streptococcus pneumoniae
Chlamydophila pneumoniae
Hemophilus influenzae
Influenza virus, adenovirus, other respiratory viruses
Legionella pneumophila
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11
Q

Bacterial causes of pneumonia

A

COMMON BACTERIAS:
Streptococcus pneumoniae : Consolidation, empyema
Group B streptococci : Neonates
Group A streptococci: Empyema
Mycoplasma pneumoniae: Adolescent, summer - fall epidemics
Chlamydophila pneumoniae: Adolescents
Chlamydia trachomatis: infants
Mixed anaerobes : Aspiration pneumonia
Gram negative enterics : Nosocomial pneumonia

UNCOMMON:
Hemophilus influenza type b : unimmunized
Staphylococcus aureus: Pneumatoceles, empyema, infants
Morxella cattarrhalis
Neisseria meningitidis
Francisella tularensis: Animal, tick, fly contact: bioterrorism
Norcardia species: immunosuppressed persons
Chlamydophila psittaci* : Bird contact( especially parkeets)
Yersinia pestis: plague; rat contact; bioterrorism
Legionella species; Exposure to contaminted water, nosocomial
Coxiella burnetii** ; Q fever; animal ( goat, sheep, cattle) exposure

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12
Q

Viral causes of pneumonia

A

COMMON:
Respiraoty syncytial virus: bronchiolitis
Parainfluenza type 1-3 : croup
Influenza A and B : High fever; winter months
Adenovirus: can be severe; often occurs between January and April
Human metapneumovirus: Similar to respiratory syncytial virus

UNCOMMON:
Rhinovirus: Rhinorrhea
Enterovirus: Neonates
Herpes simplex : Neonates
Cytomegalovirus: infants, immunosuppressed persons
Measles: Rash, coryza, conjunctivitis
Varicella: Adolescents or unimmunized
Hantavirus : Southwestern united states, rodents
Coronavirus ( Severe acute respiratory syndrome (SARS), Middle East respirtory syndrome (MERS) ; Asia, Arabian peninsula

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13
Q

Fungal causes of pneumonia

A

Histoplasma capsulatum: bird, bat contact
Blastomyces dermatitidis
Coccidioides immitis
Cryptococcus neoformans: bird contact
Aspergillus species : Immunosuppresed persons, nodular lung infection
Mucormycosis: Immunosuppressed person
Pneumocyctis jiroveci: immunosuppresed, steroids

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14
Q

Ricketsial cause of pneumonia

A

Rickettsia rickettsiae : tick bite

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15
Q

Mycobacterial cause of pneumonia

A

Mycobacterium tuberculosis: travel to endemic region, exposure to high risk persons

Mycobacterium avium complex : Immunosuppressed persons

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16
Q

Parasitic cause of pneumonia

A

Various parasites ( eg: Ascaris, Strongyloides species) : Eosinophilic pneumonia

17
Q

Immunologic defense mechanisms of lung include

A

1 - macrophages that are present in alveoli ad bronchioles

2 - Secretory IgA and other immunoglobulins

18
Q

Pathogenesis of viral pneumonia

A

Spread of infection along airway + direct injury of respiratory epithelium –> airway obstruction from swelling + abnormal secretion and cellular debris

19
Q

Pathogenises of bacterial pneumonia

A

organism colonise in trachea and gain access to lungs
direct seeding of lung tissue after bacteremia
pathologic process depends on invading bacteria

20
Q

Pathogenesis of M. Pneumoniae

A

Attaches to respiratory epithelium, inhibits ciliary action –> cellular destruction and inflammatory response in submucosa
When infection progress, sloughed cellular debris, inflammatory cells and mucus –> airway obstruction and spread infection along bronchial tree

21
Q

Pathogenesis of S. pneumoniae

A

cause local edema –> proliferation of organisms and their spread into adjacent portions of lung, –> characteristic focal lobar involvement

22
Q

Pathogenesis of Group A streptococcus

A

cause more diffuse infection with interstitial pneumonia.
Necrosis of trachobronchial mucosa, formation of large amounts of exudate, edema and local hemorrhage with extension into alveolar septa and involvement of lymphatic vessels and increased likelihood of pleural involvement

23
Q

Pathogenesis of S. aureus

A

manifests in confluent bronchopneumonia, which is often unilateral and characterized by presence of extensive areas of hemorrhagic necrosis and irregular areas of cavitation of lung parenchyma –> pneumatoceles, empyema or at time, bronchopulmonary fistulas

24
Q

Definition of recurrent pneumonia

A

2 or more episodes of pneumonia in a single year OR
3 or more episodes ever, with radiographic clearing between occurences.

  • an underlying disorder should be considered if a child experiences recurrent pneumonia
25
Q

Differential diagnosis of recurrent pneumonia

A

HEREDIATRY DISORDERS
1 - cystic fibrosis
2 - sickle cell disease

DISORDERS OF IMMUNITY
1 - HIV/AIDS
2 - bruton agammaglobulinemia
3 - selective immunooglobulin G subclass deficiencies
4 - Common variable immunodeficiency syndrome
5 - severe combined immunodeficiency syndrome
6 - Hyperimmunoglobulin E syndrome
7 - leukocyte adhesion defect

DISORDERS OF CILIA
1 - Immotile cilia syndrome
2 - Kartagener syndrome

ANATOMIC DISORDERS
1 - Pulmonary sequestration
2 - Lobar emphysema
3 - Gastroesophgeal reflux ( GERD)
4 - Foreign body
5 - Tracheoesophageal fistula ( H type)
6 - Bronchiectasis
7 - Aspiration ( oropharyngeal incoordination)
8- Aberrant bronchus
26
Q

Clinical manifestation of pneumonia

A
  • in viral fever is usually present but generally temp is lower than bacterial.
  • severe infection: cyanosis. lethargy
  • Bacterial pneumonia: in older children –> sudden fever, cough and chest pain. splinting on the affected side to minimize pleuritic pain.
    in infants ==>upper respiratory tract infection, diminished appetitie, abrupt onset of fever, restlessness, and repiratory distress. some infants with bacterial pneumonia may have GI disturbances : vomiting, anorexia, diarrhea and abdominal distention secondary to paralytic ileus.
  • abdominal pain is common in lower lobe pneumonia
27
Q

Diagnosis of pneumonia

A

1 - CXR ( PA and lateral view)
viral–> hyperinflation with bilateral interstitial inflitrates and peribronchial cuffing.
Pneumococcal pneumonia–> typically confluent lobar consolidation
Repeat CXR is NOT required for proof of cure in uncomplicated cases.
2 - Peripheral WBC
in viral –> WBC normal or elevated but not higher thn 20 000/mm3 with lymphocyte predominanace
in bacterial–> WBS between 15000 to 40 000 with granulocyte predominance
Large effusion, lobar consolidation and a high fever at onset also suggests bacterial origin.
Definitive viral diagnosis –> isolation of virus or detection of viral genome or antigen in respiratory tract secretions.
Definitive bacterial diagnosis –>isolation of organism from blood, pleural fluid or lung.
blood culture is positive only in 10% of pneumococcal pneumonia.
Blood culture is recommended for :
1 - those who fail to improve or have clinical detorioration
2 - those with complicated pneumonia
3 - those requiring hospitalization

28
Q

Factors suggesting need for hospitalization of children with pneumonia

A

1 - age < 6 months
2 - sickle cell anemia with acute chest syndrome
3 - multiple lobar involvement
4 - immunocompromised state
5 - toxic appearence
6 - moderate to severe respiratory distress
7 - requirement of suppplemental oxygen
8 - complicated pneumonia
9 - deydration
10 - vomitng or inability to tolerate oral fluids or medications
11 - no response to appropriate oral antibiotic therapy
12- social factors ( eg: inability of caregivers to administer medications at home or follow up properly)

29
Q

Complicated pneumonia is when there is

A

pleural effusion, empyema, abcess, bronchopleural fistula, necrotizing pneumonia, acute respiratory distress syndrome, hemolytic uremic syndrome, sepsis, extrapulmonary infections ( meningitis, arthritis, pericarditis, osteomyelitis, endocarditis)

30
Q

Treatment of pneumonia

A

1 - Mildly ill child who do not require hospitalization:
1 - Amoxicillin 80-90mg/kg/24hour ( high dose due to emergence of penicillin resistant pneumococci)
2 - Therapeutic alternatives: Cefuroxime axetil and amoxicillin/clavulanate

2 - School age children and in children with M. pneumoniae or C pneumoniae is suggested:
Macrolide such as azithromycin is the choice. In adolescents, a respiratory fluroquinolone ( levofloxain, moxifloxacin) maybe considered

3 - Emperic treatment of suspected bacterial pneumonia in hospitalized child:
1 - In areas without substantial penicillin resistance, and fully immunized to H.influenzae type b and S. pneumoniae, and not severely ill –> ampicillin or penicillin G.
2 - children who does not meet above criteria –> Ceftriaxone or cefotaxime

4 - If clinical features suggests staphylococcal pneumonia ( pneumatoceles, empyema), –> initial therapy should also include vancomycin or clindamycin.

5 - Viral pneumonia: antibiotic could be withheld, but 30% of patients with viral pneumonia especially influenza viruses, coexist with secondary bacterial infection. therefore in deteriorating patients antibiotic should be started.

6 - No specific duration is established by studies but generally should be continued until patient is afebrile for 72 hours and total duration should not be less than 10 days. ( or 5 days in azithromycin)
Shorter courses of 5- 7 days maybe effective, paticularly in OPD patients. Prolonged treatment not indicated in uncomplicated cases

7 - In developing countries, oral Zinc ( 10mg/day for < 12 months, 20mg/day for more than or equal to 12 months ) reduces mortality in children with clinically defined severe pneumonia.

31
Q

umcomplicated community acquired bacterial pneumonia shows response to therapy with improvement in clinical symtoms within how many hours?

A

48 to 96 hours of initiation of antibiotics

32
Q

what to consider if patient does not improve with appropriate antibiotic therapy?

A

1 - complication such as empyema
2 - Bacterial resistance
3 - non bacterial etiologies such as viruses or fungi and aspiration of foreign bodies or food
4 - bronchial obstruction from endobronchial lesions, foreign body or mucous plugs
5 - preexisting diseases such as immunodeficiencies, ciliary dyskinesia, cystic fibrosis, pulmonary sequestration or congenital pulmonary airway malformation, ( formerly called as cystic adenomatoid malformation)
6 - other non infectious causes ( including bronchiolitis obliterans, hypersensitivity pneumonitis, eosinophilic pneumonia, aspiration, and granulomatosis with polyangiitis, formerly known as Wegener granulomatosis)

  • Repeat CXR is first step to determine reason of delay
  • Bronchoalveolar lavage indicated in children with respiratory failure
  • High resolution CT scans may identify complications or anatomic reasons for poor response
33
Q

complications of pneumonia are usually a result of?

A

direct spread of bacterial infection within thoraci cavity ( pleural effusions, empyema, pericarditis) or bacteremia and hematologic spread

34
Q

Meningitis, suppurative arthritis and osteomyelitis are rare complications of?

A

hematologic spread of pneumococcal or H influenzae tybe b infection

35
Q

most common causes of parapneumonic effusion and empyema are?

A

S aureus
S pneumoniae
S pyogenes

  • many effusions that complicate bacterial pneumonia are sterile
  • Universal 16S ribosomal RNA gene polymerase chain reaction identify bacterial genome and can determine bacterial etiology of effusion if culture is negative
36
Q

treatment of empyema

A
  • based on stage ( exudative, fibrinopurulent, organizing)
  • USG and CT are helpful in determining the stage
  • therapy include: antibiotics and drainage with tube thoracostomy
  • other approaches include use of intrapleural fibrinolytic therapy ( urokinase, streptokinase, tissue plasminogen activator) and selected video assisted thoracoscopy to debride or lyse adhesions and drain loculated areas of pus.
37
Q

prevention of pneumonia

A

Vaccination

  • in 2000 7 valent pneumococcal conjugate vaccine ( PCV 7) was licensed in recommended
  • in 2010 13 valent pneumococcal conjugate vaccine (PCV13) was licensed in US

Expansion of influenza vaccine recommendation to include children more than 6 months.
Measles vaccine greatly reduced measles related pneumonia deaths

38
Q

Differentiation of pleural fluid: Transudates

A 
Appearence : clear
cell count ( per mm3) : <1000
cell type: Lymphocyte, monocyte
Lactase dehydrogenase: < 200U/L
pleural fluid : serum LDH ratio --> < 0.6
Protein > 3 g --> unusual
PLeural fluid: serum protein ration --><0.5
Glucose : normal
pH : normal ( 7.40 - 7.60)
Gram stain : Negative
Cholesterol : -
PLeural cholesterol : serum cholesterol ratio --> < 0.3
  • low Glucose or pH maybe seen in malignant effusion, TB, esophageal rupture, pancreatitis ( positive pleural amylase ), rheumatologic disease ( eg SLE)
39
Q

Differentiation of pleural fluid: Empyema ( exudates)

A

Appearence : cloudy or purulent
cell count ( per mm3) : often > 50000 ( cell count has limited predictive value)
cell type: polymorphonuclear leukocytes ( neutrophils)
Lactase dehydrogenase: more than two-thirds upper limit of normal for serum lactate dehydrogenase ( LDH)
pleural fluid : serum LDH ratio –> > 0.6
Protein > 3 g –> common
PLeural fluid: serum protein ration –> >0.5
Glucose : low ( < 40mg/dL)
pH : low < 7.10
Gram stain : occasionaly positive ( less than one third of cases)
Cholesterol : >55mg/dL
PLeural cholesterol : serum cholesterol ratio –> > 0.3

Nelsons (3 decks)

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