Dr. Adel Hamada
Lecturer of Chest Diseases
Faculty of Medicine Zagazig University
Pneumonia is defined as inflammation and consolidation of lung tissue due
to an infectious agent.
Definition of community acquired
CAP may be defined as pneumonia occurring in patients who
have not been hospitalized or living in a nursing home during
the 2 weeks prior to the onset of symptoms.
This pneumonia develops in the outpatient setting or within
48 hours of admission to a hospital
Respiratory Infections are responsible for
more office visits than chronic diseases
IMS America NDTI (National Disease Therapeutics Index). 2001.
Respiratory infections Hypertension Gastrointestinal diabetes Depression
Top 20 Indications for Antibiotics
TOP 20 INDICATIONS
FOR ANTIBIOTICS 1998-2001
Petersen et al J Antimicrob Chemother 2007;60 (Suppl 1);i43-i47
RISK FACTORS OF CAP
Increased age favors infection with S. pneumoniae, group B streptococci, Moraxella
catarrhalis, H. influenzae, gram-negative bacilli, and Chlamydophila pneumoniae.
Aspiration pneumonia risk increases with age as well as risk for pneumonia due to
Reduce bacterial clearance from the airways.
S. pneumoniae infections tend to be more severe in alcoholic patients.
Also, infections caused by gram-negative bacilli and L. pneumophila occur
more frequently in heavy drinkers.
Airway colonization is common in patients with chronic obstructive pulmonary
disease (COPD) specially H. influenzae and M. catarrhalis become more prevalent.
Very pronounced decrease in forced expiratory volume in 1 second (FEV1), along with
bronchiectasis, predisposes affected patients to infection with Pseudomonas
Conditions leading to altered level of consciousness, poor dental hygiene, history of
head and neck surgery affecting swallowing mechanisms, and upper gastrointestinal
tract disease all are predisposing factors for development of aspiration pneumonia.
Organisms such as S. pneumoniae, S. aureus, group B streptococci, and H.
influenzae frequently cause superinfections after viral illnesses such as influenza
and RSV infection.
Occupations associated with exposure to dusts, fumes, and various chemicals increase
the risk of acquiring CAP in general, with S. pneumoniae being the most likely pathogen.
Exposure to contaminated water supply and cooling towers of air-conditioning units
increases the chance of acquiring Legionnaire’s disease.
Contact with animals may lead to pneumonia due to Yersinia pestis (plague, for which
rodents constitute a natural reservoir), Francisella tularensis (tularemia, with rabbits,
voles, and muskrats as carriers), C. burnetii (Q fever, transmitted by sheep, dogs, and
cats), Rhodococcus (present in horses) or Chlamydophila psittaci (psittacosis,
transmitted by birds).
In certain settings, bioterrorism must be considered as well. Potential agents utilized
for such purposes include those organisms causing anthrax, tularemia, and plague.
Both the frequency and the severity of pneumonia increase in institutionalized
colonization by gram-negative bacilli or S. aureus plays a major role here.
Smoking alters mucociliary transport, humoral and cellular defenses, and
epithelial cell function and increases adhesion of S. pneumoniae and H. influenzae
to the oropharyngeal epithelium.
Also, smoking predisposes to infection by influenza viruses, L. pneumophila, and
Approach to the Patient with Suspected Pulmonary
Microbiology of CAP
Bartlett JG. Management of Respiratory Tract Infections 1st Ed Williams & Wilkins, 1997:1-117
0 5 10 15 20 25 30
CAUSATIVE PATHOGENS IN CAP
5755 ADULTS ADMITTED TO HOSPITAL
Most Common Etiologic Agents of Community-Acquired Pneumonia
ICU HOSPITAL COMMUNITY
42 Individual studies in Europe
HOW CAN THE CAUSATIVE
PATHOGEN BE IDENTIFIED?
Minimally Invasive Tests:
Throat Swab Examination and Other Modalities
predominantly intracellular pathogens such as viruses (including
influenza viruses), Mycoplasma, and Chlamydophila, by direct
immunofluorescence (Chlamydophila, viruses) or cell culture.
Increasingly, polymerase chain reaction (PCR) techniques are best
for noncommensal organisms.
The main problem is that organisms identified in sputum may not be
representative of what is happening in the lung.
Second, bacteria may colonize the normally sterile airways when host
defenses are compromised .
some organisms are always pathogens (e.g., Mycobacteria, Pneumocystis,
Legionella), their identification in sputum is always helpful.
Various tests can be performed on sputum; Gram stain and
routine culture are the best known
In CAP, serologic studies may be the only method of diagnosis available for
detection of Mycoplasma, Chlamydia, Coxiella, Legionella, and viral infections
it is necessary to identify a four-fold rise in specific antibody titers to at least 1
: 128 between acute and convalescent samples. A single high titer of 1 : 256 is
presumptive evidence of infection.
Blood culture is readily available and highly specific if positive. Its drawback is
its relative insensitivity: Positive culture results are obtained in only 10% to
20% of hospitalized adult patients who have CAP.
Rarely needed in CAP and is reserved for patient admitted to ICU or non
responder to empirical antibiotic therapy.
Percutaneous Fine Needle Aspiration
Open Lung Biopsy
Pleural Fluid/Tissue Sampling
When present, pleural fluid should be sampled, because the results are highly specific.
(ELISA) testing of urine for Legionella antigen is now the most frequently
performed test, yielding the most rapid results, for the diagnosis of Legionella
Urine antigen tests for S. pneumoniae probably are more sensitive and specific
than is sputum examination.
A. polymerase chain reaction (PCR) techniques, are beginning to be used
selectively for pathogen identification.
B. Other roles of PCR analysis may be to detect multiple organisms at the
same time in a single sample (so-called multiplex PCR assay) and to identify
antibiotic resistance by detection of the specific gene defect that
determines such resistance (e.g., rifampicin resistance in tuberculosis).
Clinical Indications for Diagnostic Testing for Community-Acquired Pneumonia
(Infectious Diseases Society of America/American Thoracic Society consensus
guidelines on the management of community-acquired pneumonia in adults,
SITE OF CARE
Home ( Outpatient)
Hospital( Not in ICU)
American Thoracic Society Criteria for Admission of Patients with
Community-Acquired Pneumonia to an Intensive Care Unit ICU
admission is warranted for patients who fulfill three minor criteria
or one major criterion.
LOW VOLUME OF DISTRIBUTION
INABILITY OF DIFFUSING THROUGH MEMBRANES
INACTIVE AGAINST INTRACELLULAR PATHOGENS
RENAL ELIMINATION AS UNCHANGED DRUG
HIGH VOLUME OF DISTRIBUTION
ABILITY OF DIFFUSING THROUGH MEMBRANES
ACTIVE AGAINST INTRACELLULAR PATHOGENS
ELIMINATION AFTER LIVER METABOLIZATION
Pea F, Viale P, Furlanut M. Clin Pharmacokinet 2005, 44: 1009-1034
ATS/IDSA Recommendations for Empirical Antibiotic
Treatment of Community-Acquired Pneumonia
Empirical Coverage for Uncommon Pathogens Causing
ROUTE AND DURATION OF THERAPY; HOSPITAL DISCHARGE
Most patients with CAP severe enough to warrant hospital admission are treated with
intravenous antibiotics. Switching to oral therapy should be considered once the
1- has achieved clinical stability
2- is able to tolerate oral medication
3- and has a functioning gastrointestinal tract.
Criteria for Clinical Stability
in Management of
ATS/IDSA guideline recommendations denoting 5 days as minimal duration of therapy.
Antibiotics can be discontinued once clinical stability has been achieved and
maintained for 48 to 72 hours.
More than 7 to 10 days of total antibiotic administration is rarely required, unless
extrapulmonary infections such as endocarditis or meningitis are present, initial
therapy was not active against a subsequently identified offending pathogen, or P.
aeruginosa infection, S. aureus bacteremia, or tissue necrosis was present.
Failure to achieve clinical stability using the aforementioned criteria within the
first 3 days is suggestive of nonresponse to therapy, although in up to 25% of
patients (especially those of advanced age and with multiple comorbid conditions),
6 days or longer may be needed to meet these criteria.
common causes of non-responding/deteriorating
SPECIFIC COMPLICATIONS of PNEUMONIA
PARAPNEUMONIC EFFUSION AND EMPYEMA
Recommendations for Vaccine Prevention of Community-Acquired Pneumonia