Community acquired pneumonia

Pneumonia - D
efinition
Pneumonia is an abnormal inflammatory condition of
the lung. It is often
characterized as including inflammation of the parenchyma of the lung (that is,
the alveoli) and abnor-
mal alveolar filling with fluid
(consolidation and exudation)

Community Acquired
Pn
eu
monia
Definition:
Acute infection of the pulmonary parenchyma that is associated with at least some symptoms of acute infection, accompanied by the presence of an acute infiltrate on a chest radiograph, or auscultatory findings consistent with pneumonia, in a patient not hospitalized or residing in a long term care facility for > 14 days before onset of symptoms.

Community-Acquired
Pneum
onia ( CAP )
■
Community-acquired
■
pneumonia refers to pneumonia acquired outside of hospitals or extended-care facilities.
Community-acquired pneumonia (CAP) is one of the most common infectious diseases diagnosed by clinicians.

Why Community Acquired Pneumonia
is a Important disease

changes in
CAP causes major
the Functional phy
siology of
the Respiratory tract

Who Develops Community
Acquire
d Pneumonia
Community-acquired pneumonia develops in people with limited or no contact with medical institutions or settings.
CAP occurs throughout the world and is a leading cause of illness and death

Risk Factors for pneumonia
age
alcoholism
smoking
asthma
Immuno suppression
institutionalization
COPD
dementia
Community Acquired
Pneumonia

Community acquired pneumonia Emerging Health Problem
Causes of CAP - Bacteria, viruses, fungi, and parasites. CAP can
be diagnosed by symptoms and physical
examination alone, though x-rays, examination of the sputum, and other tests are often used. Individuals with CAP sometimes require hospitalization
and treatment in a hospital.

Several Microbes can cause
CAP
■
The most commonly
identified pathogens are Streptococcus pneumoniae, Haemophilus influenzae, and atypical organisms (i.e., Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionella sp).

Typical x Atypical etiological
agents
Typical pneumonia usually is caused by
bacteria such as Streptococcus pneumoniae.
Atypical pneumonia usually is caused by
the influenza virus, mycoplasma, Chlamydia, Legionella, adenovirus, or other unidentified microorganism.
The patient's age is the main differentiating factor between typical and atypical pneumonia; young adults are more prone to atypical causes, and very young and older persons are more predisposed to typical causes.

X ray chest gives the leading
clues
in
Diagnosis

Pathophysiology
CAP is usually acquired via inhalation or aspiration of pulmonary pathogenic organisms into a lung segment or lobe. Less commonly, CAP results from secondary bacteraemia from a distant source, such as Escherichia coli urinary tract infection and/or bacteraemia. CAP due to aspiration of Oropharyngeal contents is the only form of CAP involving multiple pathogens.

Etiological agents in Community-Acquired
Pneumonia in Children
From Bi
rth to 3 weeks
Group B streptococci, Listeria Monocytogenes, gram-negative bacilli, cytomegalovirus

From 3 weeks to 3 months
Streptococcus pneumoniae, viruses (RSV, Parainfluenza viruses, metapneumovirus), Bordetella pertussis, Staphylococcus aureus, Chlamydia trachomatis (trans natal exposure)

From 4 months to 4 years
S. pneumoniae,
viruses
(RSV, Parainfluenza viruses, influenza viruses, adenovirus, rhinovirus, metapneumovirus),
Mycoplasma pneumoniae (in older children), group A streptococci

5 years to 15 years
S. pneumoniae,
M. pneumoniae, and
Chlamydia pneumoniae

COMMUNITY-ACQUIRED
PNEUMONIA IN ADULTS

Outpatients—with no
modifying factors present
■
Streptococcus
■
■
■
■
pneumoniae,
Mycoplasma pneumoniae, Chlamydia pneumoniae, Haemophilus influenzae,
respiratory viruses, miscellaneous
(Legionella sp, Mycobacterium tuberculosis, endemic fungi

Outpatients—modifying
factors present
■
S. pneumoniae, including drug
resistant forms; M. pneumoniae;
C. pneumoniae; mixed infection (bacteria + atypical pathogen or virus); H. influenzae; enteric gram-negative organisms; respiratory viruses; miscellaneous
(Moraxella catarrhal is,
Legionella sp, anaerobes [aspiration], M. tuberculosis, endemic fungi)

CAP in Inpatients not admitted
in ICU
S. pneumoniae, H. influenzae; C.Pneumonia;
C. pneumoniae; mixed
infection (bacteria +
atypical pathogen or virus); respiratory viruses; Legionella sp, miscellaneous (M. tuberculosis.

Non-bacterial pathogens causing
CAP
■
Non bacterial pathogens in the differential include many viruses (influenza, adenovirus, rhinovirus, etc.) and fungi
(Aspergillusspp., Cand ida spp., Coccidioides immitis, etc.)

Value of chest x-ray in
Diag
nosis of CAP
A chest x-ray is recommended to make the diagnosis of pneumonia
An imperfect gold standard
No studies specifically demonstrate improved patient outcomes through use of chest x- ray in adults

Microbiological Diagnosis

Common Laboratory Tests
■
Common laboratory tests
for pneumonia have included leukocyte count, sputum Gram stain, two sets of blood cultures, and urine antigens.
However, the validity of these tests has recently
been questioned after low positive culture rates were found (e.g., culture isolates of S. pneumoniae were present in only 40 to 50 percent of cases).

Microbiological diagnosis is
co
nfirmatory
■
Is not possible to distinguish the
causative organisms of pneumonia other than by microbiology as no pathogen leads to a clinical, laboratory or radiological pattern sufficiently characteristic to be the basis of a confident diagnosis, but clinical symptoms and epidemiological features may provide clues to the aetiology as some differences in presentation do occur.

Bacteriological Investigations
o
n sputum
Expectorated sputum collected ( poorly collected) without proper instructions may not yield optimal results

Sputum gram staining and
culture
A good quality sputum sample with a predominant pus cells with proportionately less epithelial cells and bacterial pathogens can be observed in approximately 15%of the cases studied

Newer methods – Diagnosis of
Community associated Pneumonias
Antigen detestation in sputum urine by
Fluorescent methods
Immunoelectrophoresis
Latex agglutination tests
ELISA

Diagnosis in cases of Atypical
P
neumonias
By serological methods using acute and convalescent sera
Raise of significant titer or rising titer of antibodies give clues to diagnosis.

Other markers suggestive of
CAP
C - reactive protein trends have been correlated to clinical progress in CAP, and administration of its activated form (drotrecogin alpha) appears to reduce mortality in severe sepsis.

Pencillin still continues to be
preferr
ed antibiotic
■
With a bloodstream or
lung infection, you can get a much higher concentration of antibiotic to the site of the infection. Because of that, you can use a standard agent, such as penicillin, even when there is some resistance,“
Dr. Whitney.

Antimicrobial therapy –
Empiri
ca approach
Antimicrobial therapy is the mainstay of management for community-acquired pneumonia (CAP). Accordingly, the choices of treatment are influenced by the likely aetiologies, local resistance patterns of the pathogens, as well as patient factors. As the leading cause of acute CAP, the susceptibility patterns of Streptococcus pneumoniae have greatly influenced antimicrobial agents and dosage recommended for empirical treatment of this condition.

MRSA – a concern in treating
Community acquired Pneumonias
The worldwide emergence of community-acquired Methicillin-
resistant Staphylococcus aureus has also led to discussion of this pathogen in recent revisions of the international CAP guidelines.

Vaccination in children
Vaccination is important in both children and adults. Vaccinations against Haemophilus influenzae and Streptococcus pneumoniae in the first year of life have greatly reduced their role in CAP in children

Community Acquired Pneumonia and
Vaccination for Pneumococcal infect ion
✔
The pneumococcal vaccine
(the ‘pneumonia shot’) protects against 23 types of pneumococcal bacteria.
✔
Research proves the vaccine is not 100% effective in preventing pneumonia, but found that if you are vaccinated you are less likely to die from pneumonia.

Preventing Inf
uenzae
According to the U.S.
■
Centers for Disease Control and Prevention (CDC), anyone who wants to reduce their risk of getting the flu should have a flu vaccine.
Older children and adults require only a single shot each year. However, children under age 9 may need two doses

General Health Measures
Smoking cessation is important not only for treatment of any underlying lung disease, but also because cigarette
smoke interferes with many of the body's natural defences against CAP.

Future goals on reducing child
deaths – by Hand washing
■
Handwashing with
soap is among the most effective and inexpensive ways to prevent diarrheal diseases and pneumonia, which together are responsible for the majority of child deaths. a significant contribution to meeting the Millennium Development Goal of reducing deaths among children under the age of five by two-thirds.