Community Acquired Pneumonia (CAP) and

Hospital Acquired Pneumonia (HAP) Treatment

Guidelines in Adults

Definition: Pneumonia is an infection that inflames the air sacs in one or both

lungs. The air sacs may fill with fluid or pus (purulent material), causing cough

with phlegm or pus, fever, chills, and difficulty breathing. A variety of

organisms, including bacteria, viruses and fungi, can cause pneumonia. Anyone

can get this lung infection. But infants younger than age 2 and people over age

65 are at higher risk. That’s because their immune systems might not be strong

enough to fight it.

Pneumonia Classifications and Risk Factors:

There are four types of pneumonia:

1. Community acquired pneumonia.

2. Hospital acquired pneumonia.

3. Ventilator associated pneumonia.

4. Aspiration pneumonia.

ETIOLOGY

Community-Acquired Pneumonia: 1) Viral (most commonly): with human rhinovirus and influenza A are the most

common.

2) Bacterial: S. pneumoniae accounting for up to 35%, other H. influenzae,

atypical pathogens M. pneumoniae, Legionella species, and C. pneumoniae.

3) Other but less common: S. aureus; in children and adults and is often seen in

patients with cystic fibrosis and those recovering from a viral respiratory

infection such as influenza. Gram-negative bacteria, including E. coli and K.

pneumoniae, those identified most frequently among patients with chronic

illness, especially alcoholism and diabetes mellitus.

Viral pathogens predominate in CAP among pediatric patients with a

prevalence of up to 80% in those less than 2 years of age.

Other common viruses in children include parainfluenza, adenovirus, and

bocavirus. Group B Streptococcus, although rare in adults, is the most

common cause of bacterial pneumonia among neonates.

Some risk factors for MRSA pneumonia include patients with preceding

influenza infection, necrotizing/cavitary radiographic findings, and

structural lung disease. Risk factors for P. aeruginosa include severe

COPD leading to repeated antibiotic exposures and structural lung

disease.

Hospital acquired pneumonia: Hospital-acquired pneumonia (HAP)

occurs most commonly in critically ill patients and is usually caused by

bacteria.

Most commonly by gram-negative aerobic bacilli or S. aureus and is

much more likely to be caused by an MDR. P. aeruginosa and

Acinetobacter spp. K. pneumoniae and E. coli are also common S.

aureus is also common with approximately half of these isolates

methicillin-resistant.

Patient more likely to have MDR organisms:

1. Structural lung disease.

2. IV antibiotic use within the previous 90 days preceding HAP

development.

Special Populations:

Pneumonia in the HIV-

Infected Patient: Patients may

be afflicted with pneumonia

multiple times, particularly in the

advanced stages of the HIV and

AIDS, and a given episode may be

caused by more than one species.

Some practitioners initially treat

the HIV-infected patient with

pneumonia empirically; however,

given the wide array of possible

pathogens, more frequently a

specific microbiologic diagnosis is

aggressively pursued early in the

patient’s course through sputum

induction or bronchoalveolar

lavage to allow a rational choice

of an antimicrobial regimen.

Pneumonia in the Neutropenic Host: Neutropenia in the cancer patient is a common complication of aggressive

chemotherapy, but occasionally results from the cancer itself. The risk of

infection for the cytopenic patient is increased significantly when the absolute

neutrophil count falls to less than 500 cells/mm3 and the neutropenia persists

for more than 7 days.

The organisms: staphylococci and streptococci, P. aeruginosa, Candida,

Aspergillus.

CLINICAL PRESENTATION AND DIAGNOSIS:

The common signs, symptoms, physical exam findings, and diagnostic features of

patients with pneumonia are listed in the following table. They are both

constitutional (fever, chills, malaise) and respiratory (cough, increased sputum

production, dyspnea). These signs and symptoms coupled with physical exam

findings suggestive of a pulmonary infiltrate, with or without abnormal white

blood cell (WBC) count or oxygen saturation, can form the basis of a presumed

clinical diagnosis of pneumonia. As for the diagnosis of pneumonia is preferably

further strengthened by radiographic evidence such as pulmonary infiltrate(s) on

chest x-ray or other chest imaging. Clinical practice guidelines recommend a

chest radiograph for all adult patients with suspected pneumonia but only in

select pediatric patients with severe CAP (e.g. inpatient, signs of

hypoxia/respiratory distress)

Pneumonia caused by the atypical pathogens, such as M. pneumoniae and C.

pneumoniae, often has a more gradual onset and overall lower severity compared

with other bacterial causes. The exception to this is Legionella pneumophila, which

is an atypical pathogen that often causes severe illness making it a common

pathogen in patients with CAP who require ICU admission.

Patients with atypical pneumonia also commonly have extrapulmonary,

constitutional symptoms. Atypical pneumonias often demonstrate patchy infiltrates

on chest x-ray that are more extensive that clinical symptoms suggest, hence the

term “walking pneumonia”.

Staphylococcal pneumonias often demonstrate cavitary or necrotizing lesions on

imaging.

Blood cultures and non-invasive sputum cultures (i.e expectorated sputum, sputum

induction, or nasotracheal suctioning) are recommended for all adult patients with

suspected HAP or VAP. Emphasis is placed on determining an etiology in HAP

and VAP due to the high prevalence of MDR organisms and associated risk of

ineffective empiric therapy. This allows adjustment of initial empiric therapy into

optimal, pathogen-specific therapy.

Confirmation of etiology is less common in CAP. As such, empiric treatment of

CAP is often continued for the entire duration of therapy without ever determining

the causative pathogen. Blood and/or sputum cultures are only routinely

recommended in patients with more severe CAP where knowledge of the causative

pathogen and whether the empiric antibiotic regimen is active and is not limited to,

patients admitted to the ICU, but those who don’t respond to the outpatient

antibiotic therapy, and those with cavitary infiltrates on chest radiograph. In

patients treated in the outpatient setting, sputum cultures are not routinely

recommended.

Treatment: Treatment Goals: Eradication of the offending organism through selection

of the appropriate antibiotic(s) and subsequent complete clinical cure is the

primary goal of therapy of pneumonia. Secondary goals include minimization

of the unintended consequences of therapy, including toxicities and selection

for secondary infections such a C. difficile or antibiotic-resistant pathogen, and

minimizing costs through outpatient and oral therapy when the patient’s

severity of illness and clinical considerations permit.

General Approach to Treatment:

CAP: Following diagnosis of CAP pneumonia, one of the first treatment decisions is

what level of medical care is necessary (i.e outpatient vs inpatient vs inpatient

ICU). This decision is ultimately made by a physician and should be based on the

patient’s severity of illness and subsequent risk of mortality.

Multiple severity scores designed to

estimate mortality risk in CAP are

available for severity assessment.

The most commonly used are the

CURB-65.

Empiric Antimicrobial Treatment:

Multiple factors can aid in identifying the potential pathogens involved,

including when and where the pneumonia was contracted, local pathogen

epidemiology and susceptibility patterns, and individual patient factors. These

individual patient factors include patient age, previous and current medication

history, underlying disease(s), major organ function, and present clinical status.

Evidence-Based Empirical Antimicrobial Therapy for

Pneumonia in Adults

Antibiotic Doses for Treatment of Bacterial Pneumonia:

Directed Antimicrobial Therapy for Common Pneumonia

Pathogens in Adult Patients: Tailoring antimicrobial therapy can also mitigate potential negative impacts of

ongoing broad-spectrum antimicrobial use, including adverse drug reactions, C.

difficile infection, and development of further MDR infection.

PATIENT MONITORING, THERAPY MODIFICATION,

AND DURATION OF THERAPY:

After therapy has been instituted, appropriate clinical parameters should be

monitored to ensure the efficacy and safety of the therapeutic regimen. For

patients with bacterial infections of the lower respiratory tract, the time to

resolution of initial presenting symptoms and the lack of appearance of new

associated symptomatology are important to determine.

For patients with pneumonia of mild to moderate clinical severity, the time to

resolution of cough, decreasing sputum production, and fever, as well as other

constitutional symptoms of malaise, nausea, vomiting, and lethargy, should be

noted.

If the patient requires supplemental oxygen therapy, the amount and need

should be assessed regularly.

Initial resolution of infection should be observed within the first 2 days of

therapy and progression to complete resolution within 5 to 7 days (usually no

more than 10 days).

The majority of hospitalized patients with CAP should be switched from IV to

oral therapy when hemodynamically stable, improving clinically as described

above, have normal gastrointestinal tract function, and be able to ingest oral

medications.

The minimum duration of therapy for CAP is 5 days although CAP is

commonly treated for 7 to 10 days.4 When discontinuing therapy, patients

should be afebrile for 48 to 72 hours and have no more than one CAP related

sign of clinical instability (i.e tachycardia, tachypnea, hypotension, hypoxia,

altered mental status).

For patients with HAP the magnitude and character of the peripheral blood

WBC count, chest radiograph, and blood gas determinations. The results of

initial and follow-up diagnostic tests, such as respiratory cultures, should also

be used alongside clinical response to streamline therapy.

Similar to patients with less severe disease, some resolution of symptoms

should be observed within 2 days of instituting antibiotic therapy. If no

resolution of symptoms is observed within 2 days of starting seemingly

appropriate antibiotic therapy or if the patient’s clinical status is deteriorating,

the appropriateness of initial antibiotic therapy should be critically reassessed.

De-escalation of antibiotic therapy to be more narrow spectrum in patients with

HAP/VAP is strongly recommended.

The recommended duration of therapy for HAP/VAP is 7 days, as the clinical

benefit of longer durations of therapy (≥10 days) is not clear based on available

clinical evidence.

Serum procalcitonin concentrations in combination with clinical response

criteria can be used in the decision to discontinue antibiotic therapy.

Prevention of Pneumonia:

Prevention of some cases of pneumonia is possible through the use of vaccines and

medications against selected infectious agents. Polyvalent polysaccharide vaccines

are available for two of the leading causes of bacterial pneumonia, S. pneumoniae

and H. influenzae type b. Children should be vaccinated against S. pneumoniae, H.

influenzae type b, pertussis, and influenza while caregivers for infants less than 6

months should also be vaccinated against influenza and pertussis. Immune

prophylaxis for RSV is only recommended for high-risk infants during RSV

season.

Reference: Pharmacotherapy and Pathophysiological Approach Dipiro 11

th Edition

Textbook.

Prepared by Pharm D Students: Yazeed Alattar , Mohammad Fakhri

Supervised by Clinical Pharmacist: Eshraq Alabweeny