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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