The document provides a comprehensive overview of pneumonia, covering its definition, pathophysiology, etiology, epidemiology, clinical manifestations, diagnosis, treatment, and prevention. It emphasizes the various microbial pathogens responsible for pneumonia, risk factors, and the importance of vaccination and appropriate antibiotic treatment based on patient conditions. The treatment strategies differ significantly between community-acquired and hospital-acquired pneumonia, with special attention to high-risk patients and potential complications.

1. Melaku Yitbarek(M.D)
Internal Medicine Unit,
March 2018

2. • Definition
• Pathophysiology
• Classification
• Clinical features
• Treatment
• Complications
• Prevention

3. Pneumonia is an infection of the
pulmonary parenchyma.
Despite being the cause of significant
morbidity and mortality, pneumonia is often
misdiagnosed, mistreated, and
underestimated

4.  Pneumonia results from the proliferation of microbial
pathogens at the alveolar level and the host’s response to
those pathogens.
 Microorganisms gain access to the lower respiratory tract in
several ways, the most common is by aspiration from the
oropharynx.
 Small-volume aspiration occurs frequently during sleep
(especially in the elderly) and in patients with decreased levels
of consciousness.
 Many pathogens are inhaled as contaminated droplets.
 Rarely,pneumonia occurs via hematogenous spread (e.g.,
from tricuspid endocarditis)or by contiguous extension from an
infected pleural or Mediastinal space.

5.  Mechanical factors are critically important in host
defense.
 The hairs and turbinates of the nares capture
larger inhaled particles before they reach the lower
respiratory tract.
 The branching architecture of the tracheobronchial
tree traps microbes on the airway lining,where
mucociliary clearance and local antibacterial
factors either clear or kill the potential pathogen.
 The gag reflex and the cough mechanism offer
critical protection from aspiration.

6.  When these barriers are overcome or when microorganisms are
small enough to be inhaled to the alveolar level, resident alveolar
macrophages are extremely efficient at clearing and killing
pathogens.
 Macrophages are assisted by proteins that are produced by the
alveolar epithelial cells (e.g., surfactant proteins A and D) and that
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.
 Only when The capacity of the alveolar macrophages to ingest or kill
the Microorganisms is exceedes does clinical pneumonia become
manifest

7.  In that situation, the alveolar macrophages initiate the
inflammatory response to bolster lower respiratory tract
defenses
 The release of inflammatory mediators, such as interleukin 1
and tumor necrosis factor, results in fever.
 Chemokines,such as interleukin 8 and granulocyte colony-
stimulating factor,stimulate the release of neutrophils and their
attraction to the lung,producing both peripheral leukocytosis
and increased purulent secretions
 Inflammatory mediators released by macrophages and the
Newly recruited neutrophils create an alveolarcapillary leak

8. The capillary leak results in a radiographic
infiltrate and rales detectable on
auscultation, and hypoxemia results from
alveolar filling.
Moreover, some bacterial pathogens
appear to interfere with the hypoxemic
vasoconstriction that would normally occur
with fluid filled alveoli, and this interference
can result in severe hypoxemia.

16. Etiology:
 The extensive list of potential etiologic agents
in CAP includes bacteria, fungi, viruses, and
protozoa
 Most cases of CAP, however, are caused by
relatively few pathogens
 Although Streptococcus pneumoniae is most
common, other organisms also must be
considered in light of the patient’s risk factors
and severity of illness

17. Typical Organisms
 S.pneumoniae,
 Haemophilus influenzae,
 and (in selected patients)
S. aureus
 and gram-negative bacilli
such as
 Klebsiella pneumoniae
and Pseudomonas
aeruginosa
Atypical organisms
 Mycoplasma pneumoniae,
 Chlamydia pneumoniae,
 and Legionella species (in
inpatients) as well as
respiratory viruses
 such as influenza viruses,
adenoviruses, human
metapneumovirus,
 and respiratory syncytial
viruses

18. Epidemiology:
 More than 5 million CAP cases occur annually in the
United States;
 usually, 80% of the affected patients are treated as
outpatients and 20% as inpatients.
 The mortality rate among outpatients is usually <1%,
 whereas among hospitalized patients the rate can
range from ~12%to 40%, depending on whether
treatment is provided in or outside of the intensive care
unit (ICU).
 The incidence rates are highest at the extremes of age

19. Risk factors:
 Risk factors for CAP include alcoholism,
asthma,immunosuppression,institutionalization, and an age of
>70 years
 In the elderly, factors such as decreased cough and gag
reflexes
 Risk factors for pneumococcal pneumonia include dementia,
seizure disorders, heart failure, cerebrovascular disease,
alcoholism, tobacco smoking, chronic obstructive pulmonary
disease, and HIV infection
 P. aeruginosa is a particular problem in patients with severe
structural lung disease, such as bronchiectasis, cystic
fibrosis, or severe chronic obstructive pulmonary disease

20. Clinical Manifestations:
CAP can vary from indolent to fulminant in
presentation and from mild to fatal in
severity.
The clinical presentation may not be so
obvious in the elderly, who may initially
display new-onset or worsening confusion
and few other manifestations

21. Hx:
• Fever
• Cough
• Chest Pain
• Fast breathing
• nausea, vomiting, and/or
diarrhea
• fatigue, headache,
myalgias, and arthralgia
PE:
 An increased respiratory
rate and use of accessory
muscles of respiration
 increased or decreased
tactile fremitus,
 and the percussion note
can vary from dull to flat,
 Crackles, bronchial breath
sounds, and possibly a
pleural friction rub may be
heard on auscultation

22. Diagnosis:
• Clincal: Hx and PE
• Laboratory findings: sputum gram stain
and culture
• Blood culture
• Imaging: Chest x-ray

23. Treatment:
Objectives
 Treat the infection.
 Prevent complications.
Identify those that are at high risk and may require hospitalization.
Ther CURB-65 scoring systems suggested to evaluate the prognosis and
determine subsequent management:
 CURB-65
 C-Confusion=1point
 U-Uremia: BUN >30/dL=1point
 R-RR >30/min= 1point
 BP <90/60=1point
 Age>65=1point
 If score is 1point, it is ok to give outpatient treatment. If the score is greater
than 1 point, the patient needs hospitalization. The higher the score, the
higher the mortality.
Non pharmacologic
 Bed rest
 Adequate hydration

24. Treatment:
Pharmacologic
• Community acquired ambulatory patients (Mild
Pneumonia):First line
 No recent antibiotic use:
 Clarithromycin, 500mg P.O., BID for 5-7 days
OR
 Azitromycin, 500mg P.O., first day then 250mg
P.O., for 4d.
OR
 Doxycycline, 100mg P.O., BID for 7-10 days.

25. Treatment:
If recent antibiotic use within 3months:
 Clarithromycin, 500mg P.O. BID for 5-7 days
OR
 Azitromycin, 500mg P.O first day then 250mg
P.O., for 4d.
PLUS
 Amoxicillin, 1000mg P.O., TID for 5 to 7 days.
OR
 Amoxicillin- clavulanate, 625mg P.O., TID for 5-
7days

26. Treatment:
Community acquired hospitalized patients
(Severe Pneumonia)
Non-pharmacologic
 Bed rest
 Frequent monitoring of temperature, blood
pressure and pulse rate in order to detect
complications early and to monitor response to
therapy.
 Give attention to fluid and nutritional replacements.
 Administer Oxygen via nasal prongs or face mask

27. Treatment… severe CAP
Pharmacologic
 The Antibiotic choice should be aimed at the most likely
causative agent.
Empiric treatment for pneumonia due to common
organisms:
First line
 Ceftriaxone, 1g I.V. OR I.M every 12-24 hours for 7 days.
OR
 Benzyl penicillin, 2-3 million IU I.V. QID for 7-10 days.
PLUS
 Azithromycin, 500mg on day 1 followed by 250mg/day on
days 2 – 5
OR
 Clarithromycin, 500mg P.O., BID for 7-10 days

28. Complications:
As in other severe infections, common
complications of severe CAP include:
• respiratory failure,
• shock and
• multi organ failure,
• coagulopathy, and exacerbation of comorbid
illnesses.
• Three particularly noteworthy conditions are
metastatic infection, lung abscess,and
complicated pleural effusion

29. Prevention:
• The main preventive measure is
vaccination :influenza and pneumococcal
vaccines
• smokers should be strongly encouraged
to stop smoking

30.  While significantly less well studied than VAP,
HAP in nonintubated patients—both inside
and outside the ICU—is similar to VAP.
 The main differences are the higher
frequency of non-MDR pathogens and the
better underlying host immunity in non
intubated patients.
 The lower frequency of MDR pathogens
allows monotherapy in a larger proportion of
cases of HAP than of VAP

31. Treatment:
Empiric treatment for commonly suspected etiologies of HAP
First line
 Ceftazidime, 1gm I.V. TID for 10-14days
PLUS
 Vancomycin 1g I.V. BID for 10-14 days
OR (particularly in the ICU setup and in ventiltor associated pneumonia)
 Imipenem-cilastatin, 500mg IV (infused slowly over 1hour) Q6h
OR
 Meropenem, 1gm IV (infused slowly over 30min) Q8h
Alternatives
 Ceftriaxone, 1-2g I.V. OR I.M. BID for 7 days.
PLUS
 Gentamicin, 3-5mg/kg I.V. QDdaily in divided doses for 7 days.
OR
 Ciprofloxacin, 500mg P.O./I.V. BID every 12 hours for 7 days.
If methicillin-resistant (MRSA) suspected
 Vancomycin, 1 g I.V. BID should be added to the existing empric
regimen

32.  HCAP represents a transition between classic
CAP and typical HAP
 Several early studies were limited topatients
with culture-positive pneumonia.
 In these studies, the incidence of MDR
pathogens in HCAP was as high as or higher
than in HAP/VAP
 Patients in nursing homes and those who
have recent hospitalization(i.e with in 90
days) are at higher risk

33. Potential etiologic agents of VAP include
both MDR and non-MDR bacterial
pathogens
Most hospitals have problems with
P.aeruginosa and MRSA
Less commonly, fungal and viral
pathogens cause VAP, usually affecting
severely immunocompromised patients.

34. • Harrison’s Principles of Internal
Medicine,19th Edition,
• Standard Treatment Guideline for general
Hospital,2014
• Uptodate 21.6

35. Thank You…