ANTIMICROBIAL CLINICAL
PRACTICE GUIDELINES
Community-Acquired
Pneumonia Pathway for Adults
Purpose
To
provide a framework for the initial evaluation and management of the immunocompetent,
adult patient with bacterial causes of CAP based on recent literature and
guidelines. Delays in the initiation of appropriate antibiotic therapy
can increase mortality, and therapy should not be postponed for the purpose of
performing diagnostic studies in patients who are clinically unstable. Antibiotics should be administered within 4
hours of presentation.
Definitions:
Community-Acquired
Pneumonia (CAP) is
defined as pneumonia that occurs within 48 hours of hospital admission or in a
patient presenting with pneumonia who does not have any of the characteristics
of healthcare associated pneumonia (hospitalized in an acute care hospital for
two or more days within 90 days of the infection; resided in a nursing home or
long-term care facility; received recent intravenous antibiotic therapy,
chemotherapy, or wound care within the past 30 days of the current infection;
or attended a hospital or hemodialysis clinic).
Severe
CAP can be defined by nine criteria: (1) need for mechanical ventilation,
(2) increase in the size of infiltrates by > 50% within 48h, (3) septic
shock or the need for pressors for > 4 h, (4) acute renal failure, (5)
respiratory rate ≥ 30 breaths/min, (6) PaO2/FiO2 < 250, (7) bilateral
pneumonia or multilobar pneumonia, (8) systolic blood pressure ≤ 90 mm
Hg, and (9) diastolic blood pressure ≤ 60 mm Hg. The need for ICU admission can be defined by
using a rule requiring the presence of two of the factors numbered 1-4 and one
of the factors numbered 5-9.
Diagnosis and Management:
All patients thought to have
pneumonia should have a chest X-ray. All
admitted patients should have an assessment of gas exchange (oximetry or
arterial blood gas), complete blood cell count and differential, complete
metabolic panel, two sets of pre-treatment blood cultures, and one
pre-treatment sputum culture if possible.
Therapy should not be delayed if a sputum culture cannot be
obtained. HIV serology, with consent,
should be considered, especially for patients aged 15-54 years. For patients with severe CAP, a Legionella culture and DFA (direct
fluorescent antibody) test should be ordered.
Empiric antibiotics should be initiated while awaiting culture and
susceptibility results.
The decision to admit a
patient should be based on clinical judgment with consideration of age,
co-morbid conditions, and factors that may compromise the safety of home
care. Additionally, a PORT Severity
Index may be calculated to assist in patient disposition decisions. If a PORT score is used, home care is recommended
for risk classes I, II, and III (see attachment A). The recommended discharge criteria are that, during the 24 h
prior to discharge, the patient should have no more than one of the following
characteristics: temperature > 37.8°C, pulse > 100 bpm, respiratory
rate > 24 breaths/min, systolic blood pressure < 90 mm Hg, and blood
oxygen saturation <90%.
Antibiotic Selection:
The
key decision in initial empiric therapy is whether the patient has risk factors
for healthcare associated pneumonia, in which case the Antibiotic Protocol for Adult NOSOCOMIAL Pneumonia Empiric Therapy must
be used. Additional factors that must be
considered are the treatment site for the patient (inpatient/outpatient,
general ward/ICU), the presence of modifying factors, and the presence of risk
factors for pseudomonas.
It
is not necessary to start all CAP patients on intravenous therapy if they can
tolerate oral therapy. However, if the
patient is being admitted to the ICU, it is typically recommended that the
patient receive at least 24 hours of intravenous therapy. Doxycycline, moxifloxacin, ciprofloxacin, and
azithromycin all have excellent oral bioavailability.
See Antibiotic
Protocol for Community-Acquired Pneumonia Empiric Therapy.
Continuation of Therapy:
Broad-spectrum
empiric antibiotic therapy must be accompanied by a commitment to choose
pathogen-specific therapy once the culture and susceptibility results are
known, which is usually within 48 – 72 hours.
Clinical improvement usually becomes apparent after the first 48–72
hours of therapy, and therefore, the selected antimicrobial regimen should not
be changed during this time unless progressive deterioration is noted or
initial microbiologic studies so dictate.
The
nonresponding patient should be evaluated for noninfectious mimics of
pneumonia, unsuspected or drug-resistant organisms, extrapulmonary sites of
infection, and complications of pneumonia and its therapy. Diagnostic testing
should be directed to whichever of these causes is likely.
Algorithm:
