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PNEUMONIA
Dr. A.Torossian, M.D., Ph. D.
Department of Respiratory Diseases
Definition
Pneumonia is an infection of the
lungs caused by bacteria, viruses,
fungi and other microorganisms.
Classifications(based on various criteria)
Anatomic or radiologic distribution
The pathogen responsible – aetiologicalclassification
The setting or mechanism of acquisition
Community-acquired pneumonia (CAP)
Pneumonia that develops in the outpatient
setting or within 48 hours of admission to
a hospital
Hospital-acquired pneumonia(HAP)
Pneumonia that develops at least 48
hours after admission to a hospital and is
characterized by increased risk of
exposure to multidrug-resistant (MDR)
organisms, as well as gram-negative
organisms
Nursing home patients with pneumonia are less likely to
present with classic signs and symptoms of the typical
pneumonia presentation, such as fever, chills, chest
pain, and productive cough, but instead often have
delirium and altered mental status
VAP may occur in as many as 10-20% of patients who
are on ventilators for more than 48 hours.
Health care-associated pneumonia
(residents of nursing home or other long-term facility)
Ventilator-associated pneumonia
Aspiration Pneumonia
Caused by the aspiration of oropharyngeal secretions into the lung
Patients with increased risk of aspiration and development of aspiration pneumonia:
Decreased ability to clear oropharyngeal secretions - poor cough or gag reflex, impaired swallowing mechanism (eg. stroke patients), etc.
Unconsciousness - seizures, coma, anesthesia
Presence of other comorbidities - anatomic abnormalities, gastroesophageal reflux
Intubation/extubation
others
Because the episode of aspiration is usually not witnessed, the diagnosis is inferred when a patient at risk of aspiration develops evidence of a radiographic infiltrate in characteristic anatomic pulmonary locations
The classic findings are in the right lower lobe
The most common bacterial pathogens
Streptococcus pneumoniae
Haemophilus influenzae
Moraxella catarrhalis
These 3 pathogens account for approximately 85% of CAP cases
Typical Community- acquired
Pneumonia
Some clues about the pathogen
Underlying chronic obstructive pulmonary
disease (COPD): H influenzae or M
catarrhalis
Recent influenza infection: Staphylococcus
aureus
Alcoholic patient presenting with “currant
jelly” sputum : Klebsiella pneumoniae
Atypical Community- acquired Pneumonia
Atypical organisms are generally
associated with a milder form of
pneumonia, the so-called "walking
pneumonia."
A feature that makes these organisms
atypical is the inability to detect them on
Gram stain or to cultivate them in
standard bacteriologic media.
Atypical pathogens
Mycoplasma pneumoniae:
Mycoplasmas are the smallest known free-living organisms in existence; they lack cell walls (and therefore are not apparent after Gram stain) but have protective 3-layered cell membranes.
Chlamydophila species (Chlamydophila pneumoniae, Chlamydophila psittaci):
Psittacosis, also known as “parrot disease” or “parrot fever”, is caused by C psittaci and is associated with the handling of various types of birds.
Atypical pathogens
Legionella species:
Legionella species are gram-negative bacteria found in freshwater; they are known to grow in complex water distribution systems; Legionella species are the causative agent of Legionnaires disease.
Coxiella burnetii:
C burnetii is the causative agent of Q Fever. It is spread from animals to humans; person-to-person transmission is unusual. Animal reservoirs typically include cats, sheep, and cattle.
Hospital-acquired pneumonia
Gram-negative bacteria
Pseudomonas aeruginosa
Klebsiella pneumoniae
Haemophilus influenzae
Escherichia coli
Acinetobacter baumannii and others
Staphylococcus aureus
Viruses, fungi, anaerobic bacteria and combinations of these
Anaerobic organisms
Pneumonia due to anaerobes typically results from aspiration of oropharyngeal contents. These infections tend to be polymicrobial and may consist of the following anaerobic species: Peptostreptococcus, Bacteroides, Fusobacterium, and Prevotella
They are often combined with aerobic species
Viruses
Common causes of viral pneumonia are:
Influenza virus A and B (subtypes of Influenza A - swine influenza - A(H1N1) virus, avian influenza - A (H5N1) virus)
Rhinovirus
Respiratory syncytial virus (RSV)
Human parainfluenza viruses (in children)
Adenoviruses (in military recruits)
Severe acute respiratory syndrome virus (SARS coronavirus)
others
Viruses that primarily cause other diseases, but sometimes cause pneumonia include:
Herpes simplex virus (HSV), mainly in newborns
Varicella-zoster virus (VZV)
Cytomegalovirus (CMV), mainly in people with immune system problems
Fungal pneumonia
Endemic fungal pathogens (eg, Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis, Paracoccidioides brasiliensis) cause infection in both healthy and immunocompromised hosts in defined geographic locations of the Americas and around the world
Opportunistic fungal organisms (eg, Candidaspecies, Aspergillus species, Mucor species, Cryptococcus neoformans) tend to cause pneumonia in patients with congenital or acquired defects in their host defenses
Parasitic pneumonia
The most common parasites involved:
Toxoplasma gondii (in HIV-infected/AIDS
patients)
Ascaris lumbricoides
Schistosoma species
others
Ethiology of CAP (European region)
cause percentage (%)
Typical pathogens 40-60
Streptococcus pneumoniae 15-25
Haemophillus inflienzae 2-10
Moraxella catarrhalis 0-5
Atypical pathogens 10-30
Mycoplasma pneumoniae 1-10
Chlamydophila pneumoniae 5-15
Legionella pneumophila 0-15
Others 5-25
Viral agents 2-15
Pneumocystis carinii 0-10
Unknown pathogen 30-60
CAP is usually acquired via inhalation
Less commonly, CAP results from
secondary bacteremia from a distant
source, such as Escherichia coli urinary
tract infection
CAP may be due to aspiration of
oropharyngeal contents in patients with
certain risks
Anamnesis
Determining the presence of pneumonia
Assessing disease severity at the time of
presentation
Identifying the causative agent
AnamnesisSymptoms - Pulmonary
Cough - the presence of cough, particularly cough productive of sputum, is the most consistent presenting symptom
Sputum - the character of the sputum may suggest a particular pathogen, for example:
Rust-colored sputum - S. pneumoniae
“Currant jelly” sputum – K. pneumoniae
Foul-smelling or bad-tasting sputum - anaerobic infections
Chest pain, dyspnea, hemoptysis
AnamnesisSymptoms – Non-pulmonary
Nonspecific - fever, rigors or shaking chills,
malaise
Other nonspecific symptoms - myalgia,
arthralgia, headache - often seen in cases with
atypical pneumonia
Sometimes nausea, vomiting, diarrhea, and
altered sensorium, others
Additional host factors
Comorbid conditions
Possibility of immunosuppression
Social history
Family history
Medication history
Allergy history
Anamnesis
Anamnesis
Potential exposures
Exposure to contaminated air-conditioning or
water systems - Legionella species
Exposure to overcrowded institutions (eg. jails,
homeless shelters) – S pneumoniae,
Mycoplasma pneumoniae
Exposure to various types of animals - cats,
sheep, goats (C burnetii) or birds (C psittaci), etc.
Anamnesis
Aspiration risks
Alcoholism
Altered mental status
Anatomic abnormalities, congenital or acquired
Dysphagia
GERD (gastro-esophageal reflux disease)
Seizure disorder, unconsciousness
Anesthesia
others
Risk Factors for severe disease
Age over 65 years
Recent antibiotics
Immune compromised host (e.g. HIV Infection)
Chronic respiratory illness (COPD, Asthma)
Diabetes mellitus
Chronic liver and kidney disease
Cancer
Physicalexamination
Hyperthermia (fever, typically >38°C) or hypothermia (<36°C)
Tachypnea (>18 respirations/min)
Use of accessory respiratory muscles
Tachycardia (>100 bpm) or bradycardia (<60 bpm)
Central cyanosis
Altered mental status
Physicalexamination
Adventitious breath sounds, such as
rales/crackles, rhonchi or wheezes
Decreased intensity of breath sounds,
bronchial breath sound
Bronchophony, whispering pectoriloquy
Dullness to percussion
HOW TO DIFFERENTIATE BETWEEN PNEUMONIA AND OTHER RESPIRATORY TRACT INFECTIONS?
A patient should be suspected of having pneumonia when the following signs and symptoms are present:
an acute cough and one of the following:
new focal chest signs,
dyspnoea,
tachypnoea,
fever > 4 days.
If pneumonia is suspected, a chest X-ray should be performed to confirm the diagnosis.
Imaging methods
Chest X-ray
Radiology is generally helpful in detecting suspected pneumonia and identifying the presence of complications
only occasionally can imaging suggest specific pathogens
Computed tomographyCT scanning may identify pulmonary infections earlier than plain radiography. In most cases, it can be helpful in the analysis of more complex lung findings and evaluation of other intrathoracic structures.
Ultrasonography
Ultrasonography is useful in evaluating suspected parapneumonic effusions, especially if septations are present within the fluid collection
Laboratory tests
The amount of laboratory and microbiological work-up should be determined by the severity of pneumonia
C-reactive protein
In patients with a suspected pneumonia a test for serum-level of C-reactive protein (CRP) can be done. A level of CRP <20 mg/L at presentation, with symptoms for >24 h, makes the presence of pneumonia highly unlikely; a level of >100 mg/L makes pneumonia likely
Complete Blood Count
Sputum Gram stain
Sputum Culture
Urine antigen testing for pneumococcus
and Legionella pneumophila
Immunological tests – IgM
antibody, complement fixation test
PCR
In more severe cases:
Blood culture, prior to antibiotic therapy
Endotracheal aspirate for culture in intubated patients
Culture and study of pleural fluid if effusion is present
Arterial blood gas (if serious dyspnea is present)
Procedures
Bronchoscopy with or without
bronchoalveolar lavage (BAL)
Thoracocentesis: in patients with a
parapneumonic pleural effusion
Treatment – Where? And how?
initial assessment of severity
need for hospitalization
level of care (outpatient, medical ward
care, or medical ICU care)
mild moderate severe
Out-patient hospital ICU
Gr.1 Gr. 2 Gr. 3 Gr. 4 Gr. 5
Ramirez, Dis Manage Heart Outcomes 2003; 11 (1) 33-43
Place of treatment
Severity
Various systems to assess the severity of
disease and risk of death exist and are in
wide use, including the PSI/PORT (ie,
Pneumonia Severity Index/Patient
Outcomes Research Team score), CURB-
65 and others
CURB-65
CURB-65
One point is given for the presence of each of the following:
Confusion of new onset - Altered mental status
Uremia - BUN greater than 7 mmol/l
Respiratory rate - Greater than or equal to 30 breaths per minute
Blood pressure - Systolic less than 90 mm Hg or diastolic less than 60 mm Hg
Age older than 65 years
Patients are stratified for risk of death as follows:
0 or 1: low risk (less than 3% mortality
risk)
2: intermediate risk (3-15% mortality risk)
3 to 5: high risk (more than 15% mortality
risk)
BTS guidelines
Thorax 2009;64(Suppl
III):iii1–iii55.
doi:10.1136/thx.2009
Treatment of mild CAP
Amoxicillin or tetracycline should be used as
the antibiotic of first choice
Macrolide such as azithromycin,
clarithromycin, or roxithromycin is a good
alternative in countries with low
pneumococcal macrolide resistance
Treatment with levofloxacin or moxifloxacin
may also be considered
Duration of medication
Usually 8 - 10 days
Atypical pathogens - min 14 days (usually 2-3 weeks)
Clinical improvement is expected during the first 2-3 days
The patients should be instructed to contact the physician if there is no improvement
Treatment options for hospitalized patients with community-acquired pneumonia (no need for intensive care treatment)
(in alphabetical order)
Aminopenicillin ± macrolide
Aminopenicillin/beta-lactamase inhibitor ±macrolide
Non-antipseudomonal cephalosporin
Cefotaxime or ceftriaxone ± macrolide
Levofloxacin
Moxifloxacin
Penicillin G ± macrolide
Start empiric antibiotic treatment within 4
hours of hospitalization
– Decreases mortality
– Decreases length of stay
Offer antibiotic therapy as soon as possible
after diagnosis, and certainly within 4 hours
Choose antibiotic therapy in accordance with
local hospital policy (which should take into
account knowledge of local microbial
pathogens) and clinical circumstances for
patients with hospital-acquired pneumonia
Treatment of HAP
Piperacillin-tazobactam
Cefepime
Ceftazidime
Levofloxacin
Ciprofloxacin
Imipenem
Meropenem
Aztreonam
Amikacin
Gentamicin
Tobramycin
Vancomycin
Linezolid
Treatment options for patients
with HAP
Additional supportive care measures:
Analgesia and antipyretics
Intravenous fluids (and, conversely, diuretics) if indicated
Oxygen supplementation
Respiratory therapy, including treatment with bronchodilators, mucolytics/antitussives
Chest physiotherapy, early mobilization
Low molecular heparin in patients with acute respiratory failure
Steroids have no place in the treatment of pneumonia unless septic shock is present!
Suctioning and bronchial hygiene
Mechanical ventilation
Clinical response to antibiotic therapy should be
evaluated within 48 - 72 h of initiation. With
appropriate antibiotic therapy, improvement in
the clinical manifestations of pneumonia should
be observed in 48-72 h
Because of the time required for antibiotics to
act, antibiotics should not be changed within the
first 72 hours unless marked clinical
deterioration occurs
WHEN SHOULD IV BE USED AND WHEN SHOULD THE SWITCH
TO ORAL OCCUR?
In mild pneumonia, treatment can be applied orally from the beginning
In patients with moderate pneumonia, sequential treatment should be considered – i.v. during the first days, then switching to oral
The optimal time to switch to oral treatment is unknown - it seems reasonable to target this decision according to the resolution of the most prominent clinical features at admission
The timing of radiologic resolution of
pneumonia varies with patient age and
the presence or absence of an underlying
lung disease. The chest radiograph
usually clears within 4 weeks in patients
younger than 50 years without underlying
pulmonary disease.
If patients do not improve within 72 hours, anorganism that is not susceptible to the initialempiric antibiotic regimen should be considered.Lack of response may also be secondary to acomplication such as empyema or abscessformation
Consider broadening the differential diagnosis toinclude noninfectious etiologies such asmalignancies, congestive heart failure, etc., orother pathogens - M.tuberculosis
Further Outpatient Care
When treated in an outpatient setting, arranging
adequate follow-up evaluations for the patient is
mandatory. Patients also should be instructed to
return if their condition deteriorates
Patients should have a follow-up chest
radiograph to ensure resolution of consolidation.
Complications
Necrotizing pneumonia/Pulmonary abscess
Fibrosis/organization of lung parenchyma
Bronchiectasis
Empyema
Respiratory failure
Acute respiratory distress syndrome
Differential diagnosis
Pulmonary Thromboembolsm
Heart failure
Tuberculosis
Lung cancer
Metastatic lung
Fibrosis
Collagenosis
Others
Prognosis
Generally, the prognosis is good in otherwise healthy patients with uncomplicated pneumonia
Advanced age, aggressive organisms (eg, Klebsiella, Legionella, resistant S.pneumoniae), comorbidity, respiratory failure, neutropenia, and features of sepsis, alone or in combination, increase morbidity and mortality
Guidelines for the management of adult lower respiratory tract infections –
M. Woodhead, F. Blasi, S. Ewig, J. Garau, G. Huchon, M. Ieven, A. Ortqvist, T. Schaberg, A. Torres, G. van der Heijden, R. Read and T. J. M. Verheij, Joint Taskforce of the European Respiratory Society and European Society for Clinical Microbiology and Infectious Diseases, 2011
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