Download Pneumonia H2012

Pneumonia
H2012 -Chapter 257
Infection of the pulmonary parenchyma
Proliferation of microbial pathogens at
the alveolar level and the host's
response to those pathogens
Most common :aspiration from the
oropharynx
Many inhaled as contaminated droplets
Rarely, hematogenous spread (tricuspid
endocarditis)
Contiguous extension from an infected
pleural or mediastinal space.
Mechanical factors
Hairs and turbinates of the nares
Branching architecture of the
tracheobronchial tree(where mucociliary
clearance and local antibacterial factors
either clear or kill)
Gag reflex and Cough
Normal flora of the oropharynx,
components are remarkably constant
Macrophages are extremely efficient at
clearing and killing pathogens.
Local proteins (e.g., surfactant proteins A
and D) have intrinsic opsonizing properties
or antibacterial or antiviral activity
Once engulfed by the macrophage, the
pathogens—even if they are not killed—are
eliminated via either the mucociliary
elevator or the lymphatics and no longer
represent an infectious challenge
The host inflammatory
response, rather than the
proliferation of microorganisms,
triggers the clinical syndrome of
pneumonia
Community-Acquired Pneumonia
Bacteria, Fungi, Viruses, Protozoa
Newly :
Hantaviruses, Metapneumoviruses,
Coronavirus responsible for severe
acute respiratory syndrome (SARS),
and community-acquired strains of
methicillin-resistant Staphylococcus
aureus (MRSA)
Most Common
Streptococcus Pneumoniae
Typical
Streptococcus Pneumoniae
Haemophilus Influenzae
S. Aureus
Klebsiella Pneumoniae
Pseudomonas Aeruginosa
Atypical
(in outpatients)
Mycoplasma pneumoniae
Chlamydia pneumoniae
(in inpatients)
Legionella spp
Influenza viruses
Adenoviruses
Respiratory Syncytial Viruses
Atypical organisms
Cannot be cultured on standard
media, nor can they be seen on
Gram's stain.
Intrinsically resistant to all β-lactam
agents and must be treated with a
Macrolide, Fluoroquinolone,
Tetracycline
Virus may be responsible for up to
18% of cases of CAP that require
admission to the hospital
10–15% of CAP
Polymicrobial
often Typical + Atypical
‫الهی ! ما را آن ده که ما را آن به !‬
Microbial Causes of Community-Acquired
Pneumonia, by Site of Care
Outpatients
Non-ICU
ICU
S. pneumoniae S. pneumoniae S. pneumoniae
M. pneumoniae M. pneumoniae
S. aureus
H. influenzae
C. Pneumoniae
Legionella
C. pneumoniae
H. influenzae
Gram-negative
Respiratory v.a
Legionella
H. influenzae
Respiratory virusesa
listed in descending order of frequency
aInfluenza
A and B viruses, adenoviruses, respiratory
syncytial viruses, parainfluenza viruses
Anaerobes
Only when an episode of aspiration
days to weeks before presentation pneumonia
Alcohol
Drug Overdose
Seizure
Gingivitis
often complicated by abscess formation and
significant empyemas or parapneumonic
effusions.
S. aureus
Complicate influenza infection
MRSA reported as the primary etiologic
agent of CAP
still relatively uncommon, necrotizing
pneumonia
MRSA from hospital to the community
Genetically distinct strains of MRSA in the
community
Despite a careful history , physical
examination and routine radiographic, the
causative pathogen in a case of CAP is
difficult to predict
In more than One-Half of cases, a specific
etiology is never determined
Epidemiologic and risk factors may suggest
the involvement of certain pathogens
Epidemiologic Factors Suggesting
Possible Causes of CommunityAcquired Pneumonia
Alcoholism
Streptococcus pneumoniae
Oral anaerobes
Klebsiella pneumoniae
Acinetobacter spp
Mycobacterium tuberculosis
COPD and/or smoking
Haemophilus influenzae
Pseudomonas
aeruginosa
Legionella spp.
S. Pneumoniae
Moraxella catarrhalis
Risk factors for CAP
Alcoholism
Asthma
Immunosuppression
Institutionalization
≥70 years
Risk factors for pneumococcal
pneumonia
Dementia
Seizure disorders
Heart failure
Cerebrovascular disease
Alcoholism
Tobacco smoking
COPD
CA-MRSA Pneumonia
Skin colonization
Infection with CA-MRSA
P. aeruginosa
Bronchiectasis
Cystic fibrosis
Severe COPD
Legionella
Diabetes
Hematologicmalignancy
Cancer
Severe renal disease
HIV infection
Smoking Male
Recent Hotel stay or Ship cruise
Clinical Manifestations
Indolent to Fulminant
Mild to Fatal
Frequently Febrile with Tachycardia
Chills
Sweats
Cough
Nonproductive or Productive
Mucoid, Purulent, Blood-tinged
If the pleura is involved, : Pleuritic
Chest Pain
20% : Gastrointestinal symptoms
Nausea, Vomiting, Diarrhea
Other symptoms may include
Fatigue, Headache, Myalgias,
Arthralgias
Auscultation
Crackles
Bronchial breath sounds
Pleural friction rub
Diagnosis
1:Is this pneumonia?
Clinical and Radiographic methods
2:what is the likely etiology?
aid of Laboratory techniques
Clinical Diagnosis
Acute bronchitis
Acute exacerbations of chronic
bronchitis
Heart failure
Pulmonary embolism
Radiation pneumonitis.
Physical Examination
Sensitivity and Specificity
58% and 67%
Chest radiography is often necessary to
differentiate CAP from other conditions
Cavitation or Multilobar
Occasionally, CXR suggest an etiologic diagnosis.
Pneumatoceles :S. aureus
Upper-lobe cavitating :Tuberculosis
CT is rarely necessary
suspected postobstructive
pneumonia caused by a Tumor or
Foreign body
Outpatients
Clinical and Radiologic
usually all that is done before
treatment for CAP
since most laboratory results are not available soon
enough to influence initial management significantly
Rapid Diagnostic Tests
Influenza virus infection can
prompt specific anti-influenza drug
treatment and secondary prevention
Etiologic Diagnosis
Exposure to birds
Chlamydia psittaci
Exposure to rabbits
Francisella tularensis
Local influenza activity
Influenza virus
S. pneumoniae
S. aureus
Travel to southwestern United
States
Hantavirus
Coccidioides spp.
Dementia, stroke, decreased level
of consciousness
Oral anaerobes
Gram-negative enteric bacteria
Severity
Cavitation
Multilobar
Etiologic Diagnosis
Pneumatoceles : S. Aureus
Upper-lobe cavitating : Tuberculosis
CT
Rarely necessary
Postobstructive pneumonia
Tumor or Foreign body
Etiologic Diagnosis
Except for the 2% of CAP patients
who are admitted to the ICU
no data exist to show that treatment
directed at a specific pathogen is
statistically superior to empirical
therapy
Mycobacterium tuberculosis and influenza
Gram's stain
main purpose of the sputum Gram's stain is to ensure
that a sample is suitable for culture
S. pneumoniae, S. aureus, Gram-negative bacteria
Adequate for Culture
>25 Neutrophils
<10 Squamous epithelial cells
per low-power field
Bacteremic Pneumococcal
Pneumonia
positive cultures from sputum
samples is 50%.
Blood Cultures
Only ~5–14% of cultures of
blood from patients hospitalized
with CAP are positive, and the
most frequently isolated
pathogen is S. pneumoniae
Blood cultures are no longer
considered for all hospitalized CAP
patients.
Neutropenia secondary to pneumonia,
Asplenia, or Complement deficiencies;
Chronic liver disease; or Severe CAP—
should have blood cultured
Antigen Tests
Legionella antigens in urine
Only serogroup 1
Most community-acquired
Sensitivity and Specificity
high as 90% and 99%
Antigen Tests
Pneumococcal Urine Antigen
Sensitive and Specific
80% and >90%
False-positive results can be obtained with
samples from pneumococcus-colonized
Children
Both tests can detect antigen even after the
initiation of appropriate antibiotic therapy
Rapid test for Influenza virus and
direct fluorescent antibody tests for
influenza
Respiratory Syncytial Virus; the latter
tests are only poorly sensitive
PCR
DNA or RNA
L. Pneumophila
Mycobacteria
M. Pneumoniae
C. Pneumoniae
PCR is generally limited to research studies
Pneumococcal Pneumonia
increased bacterial load documented
by PCR is associated with an increased
risk of septic shock, need for
mechanical ventilation, and death.
Such a test could conceivably help
identify patients suitable for ICU
admission.
Serology
A fourfold rise in specific IgM between
acute- and convalescent-phase serum is
generally considered diagnostic
Coxiella burnetii
Recently, however, they have fallen out
of favor because of the time required to
obtain a final result for the convalescentphase sample.
Treatment: CAP
Certain patients clearly can be
managed at Home, and others
clearly require treatment in the
Hospital
S. Pneumoniae
Risk factors for penicillin-resistant
:Recent antimicrobial therapy, Age of <2
or >65 years, Attendance at day-care
centers, recent Hospitalization, and HIV
Resistant to Three or more antimicrobial classes
with different mechanisms considered MDR
Penicillin ,Macrolides, Tetracyclines, Trimethoprimsulfamethoxazole
Initial Antibiotic Management
Macrolide + Cephalosporin
or
a Fluoroquinolone alone
Outpatients
Previously healthy and no antibiotics in past 3 months
A macrolide [Clarithromycin (500 mg PO bid) or Azithromycin (500 mg PO
once, then 250 mg qd)] or
Doxycycline (100 mg PO bid)
Comorbidities or antibiotics in past 3 months: select an alternative from a
different class
A respiratory fluoroquinolone [Moxifloxacin (400 mg PO qd), Gemifloxacin
(320 mg PO qd), Levofloxacin (750 mg PO qd)] or
A -lactam [preferred: high-dose Amoxicillin (1 g tid) or Amoxicillin/clavulanate
(2 g bid); alternatives: Ceftriaxone (1–2 g IV qd), Cefpodoxime (200 mg PO
bid), Cefuroxime (500 mg PO bid)] plus a Macrolidea
In regions with a high rate of "high-level" pneumococcal macrolide resistance,b
consider alternatives listed above for patients with comorbidities.
Inpatients, Non-ICU
A respiratory fluoroquinolone [Moxifloxacin (400 mg PO or IV
qd), Gemifloxacin (320 mg PO qd), Levofloxacin (750 mg PO or
IV qd)]
A -lactamc [Cefotaxime (1–2 g IV q8h), Ceftriaxone (1–2 g IV
qd), Ampicillin (1–2 g IV q4–6h), Ertapenem (1 g IV qd in
selected patients)] plus a macrolided [oral Clarithromycin or
Azithromycin (as listed above for previously healthy patients) or
IV azithromycin (1 g once, then 500 mg qd)]
Inpatients, ICU
A -lactame [cefotaxime (1–2 g IV q8h), ceftriaxone (2 g IV qd), ampicillinsulbactam (2 g IV q8h)] plus
Azithromycin or a fluoroquinolone (as listed above for inpatients, non-ICU)
Special Concerns
If Pseudomonas is a consideration
An antipneumococcal, antipseudomonal -lactam [piperacillin/tazobactam (4.5 g IV
q6h), cefepime (1–2 g IV q12h), imipenem (500 mg IV q6h), meropenem (1 g IV
q8h)] plus either ciprofloxacin (400 mg IV q12h) or levofloxacin (750 mg IV qd)
The above -lactams plus an aminoglycoside [amikacin (15 mg/kg qd) or tobramycin
(1.7 mg/kg qd) and azithromycin]
The above -lactamsfplus an aminoglycoside plus an antipneumococcal
fluoroquinolone
If CA-MRSA is a consideration
Add linezolid (600 mg IV q12h) or vancomycin (1 g IV q12h).
aDoxycycline
(100 mg PO bid) is an
alternative to the macrolide
Management of bacteremic
pneumococcal pneumonia
Controversial: nonrandomized studies suggest that
combination therapy (especially with a macrolide
and a -lactam) is associated with a lower mortality
rate than monotherapy, particularly in severely ill
patients. The exact reason is unknown, but possible
explanations include an Additive or Synergistic
antibacterial effect, Antimicrobial tolerance,
Atypical co-infection, or the Immunomodulatory
effects of the macrolides
Duration of treatment for CAP
Previously treated for 10–14 days
Fluoroquinolones and Telithromycin : 5-day
course is sufficient for otherwise uncomplicated
CAP.
Even a Single dose of Ceftriaxone has been
associated with a significant cure rate.
A longer course is required for patients with
bacteremia, metastatic infection, or infection with a
virulent pathogen such as P. aeruginosa or CAMRSA.
General Considerations
Adequate hydration, oxygen therapy for
hypoxemia, and assisted ventilation
severe CAP who remain Hypotensive
despite fluid resuscitation may have
adrenal insufficiency and may respond to
Glucocorticoid treatment
Immunomodulatory therapy in the form of drotrecogin alfa (activated) should be
considered for CAP patients with persistent septic shock and APACHE II scores of
25, particularly if the infection is caused by S. pneumoniae
Failure to Improve
Slow to respond to therapy reevaluated at about day 3
(sooner if is worsening)
Pulmonary edema, Pulmonary embolism, Lung
carcinoma, Radiation , Hypersensitivity pneumonitis,
, Connective tissue disease involving the lungs
Resistant to the drug selected, or a sequestered focus
(e.g., a lung abscess or empyema)
Also possible that CAP is the correct diagnosis but
that an unsuspected pathogen (e.g., CA-MRSA, M.
tuberculosis, or a fungus) is the cause
Complications
Respiratory failure, Shock and
Multiorgan failure, Coagulopathy
Metastatic infection, Lung abscess, and
complicated Pleural Effusion. Metastatic
infection (e.g., Brain abscess or
Endocarditis)
Pleural Effusion
should be tapped for both Diagnostic
and Therapeutic purposes.
PH of <7, a Glucose level of <2.2
mmol/L, and a LDH >1000 U/L or if
bacteria are seen or cultured, then the
fluid should be drained; a Chest Tube is
usually required.
Follow-Up
Fever and Leukocytosis usually resolve 2–4 days
Physical findings may persist longer
CXR may require 4–12 weeks to clear
Age and Underlying lung disease
particularly for elderly patients follow-up
radiograph can be done ~4–6 weeks later
relapse or recurrence :particularly in the same lung
segment, underlying neoplasm must be considered.
Prognosis
Age, Comorbidities, and site of treatment (inpatient
or outpatient)
Young well and usually recover fully after ~2
weeks
Older patients and those with comorbid conditions
can take several weeks longer to recover fully
Mortality rate for the outpatient group is <1%
For patients requiring hospitalization, the overall
mortality rate is estimated at 10%, with ~50% of
deaths directly attributable to pneumonia.
Prevention
Main preventive measure is Vaccination
Influenza and Pneumococcal
influenza outbreak, vaccinated
immediately and given
chemoprophylaxis with either
Oseltamivir or Zanamivir for 2
weeks—i.e., until vaccine-induced
antibody levels are sufficiently high
Nosocomial superinfections—
both pulmonary and
extrapulmonary—are possible
explanations for failure to
improve or worsening
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