RxCe - Treatment of Community-Acquired Pneumonia in A Materials

TREATMENT OF COMMUNITY-ACQUIRED PNEUMONIA IN ADULTS: A TEAM-BASED APPROACH

Faculty:

L. Austin Fredrickson, MD, FACP

L. Austin Fredrickson is an Associate Professor of Internal Medicine at Northeast Ohio Medical University, where he serves as core faculty and teaches diagnostics, therapeutics, clinical skills, and health humanities. He is board-certified in general internal medicine and practices rural primary care. 

Liz Fredrickson, PharmD, BCPS

Liz Fredrickson, PharmD, BCPS, is an Associate Professor of Pharmacy Practice and Pharmaceutical Sciences at the Northeast Ohio Medical University (NEOMED) College of Pharmacy, where she is course director of the Parenteral Products and Basic Pharmaceutics Lab courses.

Pamela Sardo, PharmD, BS

Pamela Sardo, PharmD, BS, is a freelance medical writer and licensed pharmacist. She is the founder and principal at Sardo Solutions in Texas. Pam received her BS from the University of Connecticut and her PharmD from the University of Rhode Island. Pam’s career spans many years in retail, clinics, hospitals, long-term care, Veterans Affairs, and managed health care responsibilities across a broad range of therapeutic classes and disease states.

Abstract

Community-acquired pneumonia is a lung infection acquired outside the hospital. The American Thoracic Society and the Infectious Diseases Society of America published guidelines for community-acquired pneumonia that outline criteria for severe pneumonia. The Pneumonia Severity Index is also used to help determine whether a patient needs hospitalization. Various antibiotics may be used to treat community-acquired pneumonia. The guidelines emphasize the importance of clinical judgment and experience in patient care, including the management of immunocompetent adults. This continuing education activity reviews current evidence and guideline-based recommendations for CAP, emphasizing an interprofessional approach that integrates timely diagnosis, appropriate empiric therapy, and coordinated follow-up to enhance patient outcomes and antibiotic stewardship across care settings.

Accreditation Statements

In support of improving patient care, RxCe.com LLC is jointly accredited by the Accreditation Council^TM for Continuing Medical Education (ACCME^®), the Accreditation Council for Pharmacy Education (ACPE^®), and the American Nurses Credentialing Center (ANCC^®), to provide continuing education for the healthcare team.

Joint Universal Activity Number: The Joint Accreditation Universal Activity Numbers assigned to this activity are as follows:

Pharmacists: JA4008424-0000-26-100-H01-P

Pharmacy Technicians: JA4008424-0000-26-100-H01-T

Credits: 2 contact hour(s) (0.2 CEU(s)) of continuing education credit.

Credit Types:

Pharmacy - 2 Credits

Type of Activity: Application

Media: Computer-Based Training (i.e., online courses)

Estimated time to complete activity: 2 contact hour(s) (0.2 CEU(s)), including Activity Pre-Test, Post-Test, and Activity Evaluation.

Release Date: June 22, 2026 Expiration Date: November 3, 2028

Target Audience: This educational activity is for Pharmacists and Pharmacy Technicians

How to Earn Credit: From June 22, 2026, through November 3, 2028, participants must:

Read the “learning objectives” and “author and planning team disclosures;”

Take the “Educational Activity Pre-Test;”

Study the section entitled “Educational Activity;” and

Complete the Educational Activity Post-Test and Activity Evaluation. The Educational Activity Post-Test will be graded automatically. Following successful completion of the Educational Activity Post-Test with a score of 70% or higher, a statement of participation will be made available immediately. (No partial credit will be given.)

CE Credits: Credits for this course will be uploaded to CPE Monitor^® for pharmacists and pharmacy technicians.

Statement of Need

Community-acquired pneumonia is a lung infection acquired outside the hospital. The American Thoracic Society/Infectious Diseases Society of America guidelines emphasize the importance of clinical judgment and experience in patient care. A review of the current evidence and guidelines for CAP is needed to support timely diagnosis, appropriate empiric therapy, and coordinated follow-up.

Learning Objectives: Upon completion of this educational activity, participants should be able to:

Recall the diagnostic criteria for community-acquired pneumonia (CAP)

Recognize risk factors and prevention techniques for community-acquired pneumonia

Identify options for treating CAP in outpatient settings

Compare and contrast options for treating CAP within inpatient settings

Disclosures

The following individuals were involved in planning, developing, and/or authoring this activity: L. Austin Fredrickson, MD, FACP; Liz Fredrickson, PharmD, BCPS; and Pamela Sardo, PharmD, BS. None of the individuals involved in developing this activity has a conflict of interest or financial relationships related to the subject matter. There are no financial relationships or commercial or financial support relevant to this activity to report or disclose by RxCe.com or any of the individuals involved in the development of this activity. © RxCe.com LLC 2026: All rights reserved. No reproduction of all or part of any content herein is allowed without the prior, written permission of RxCe.com LLC.

Educational Activity Pre-Test

According to the American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA), _____________________ is a major criterion for severe CAP.

Confusion/disorientation

Thrombocytopenia

Septic shock requiring vasopressors

Multilobar infiltrates

Which of the following is standard therapy for a non-severe inpatient with CAP and no risk factors for MRSA or Pseudomonas?

Ampicillin-sulbactam + azithromycin

Amoxicillin monotherapy

Vancomycin + cefepime

Azithromycin monotherapy

Which of the following regimens would be most appropriate for an outpatient with COPD and diabetes?

Azithromycin monotherapy

Doxycycline monotherapy

Amoxicillin-clavulanate plus azithromycin

Linezolid monotherapy

Educational Activity

Treatment of Community-Acquired Pneumonia in Adults: A Team-Based Approach

Introduction

Background of Community-Acquired Pneumonia

Pneumonia is an infection of one or both lungs that causes alveoli to fill with fluid or pus.¹ Community-acquired pneumonia (CAP) is pneumonia that is acquired outside of the hospital setting.² It is a leading cause of infectious morbidity and mortality across all age groups and presents a persistent challenge for healthcare systems worldwide.³ Prompt recognition, accurate risk stratification, and evidence-based management are critical to improving patient outcomes.²

In 2019, the American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA) released updated clinical practice guidelines that redefined diagnostic and therapeutic strategies for CAP.⁴ Building on this framework, the 2023 ATS/IDSA clinical pathway has refined criteria for empiric coverage of MRSA and Pseudomonas, encouraging stewardship through shorter treatment durations and early de-escalation, and offering clear algorithms to guide site-of-care decisions.² These recommendations challenge clinicians to balance efficacy with antimicrobial conservation.²

Epidemiology and Etiology

Community-acquired pneumonia is associated with high morbidity and mortality, especially in the over-65 age group.³ It is often diagnosed without the use of a chest radiograph, sputum Gram stain, and culture in the outpatient setting.⁴ Confirmation of diagnosis is ideal when available, such as in inpatient settings, due to the inaccuracy of clinical signs and symptoms alone for diagnosis.³ Data collected by the CDC show that more than 47,000 individuals died from pneumonia in the United States in 2020.⁵

Risk factors for developing pneumonia include adults over 65, children younger than 5 years, individuals with ongoing medical conditions, and individuals who smoke cigarettes.^6-8 Risk factors for CAP are listed in Table 1 below. Staying current with vaccinations is key to help prevent infection.⁵ Additionally, care teams should counsel patients to avoid individuals who are sick and stay away from others while sick to help decrease the spread of respiratory infections.⁵ The spread of respiratory infections can also be decreased by regular hand washing, cleaning and disinfecting commonly touched surfaces, and coughing and sneezing into a tissue or elbow. Limiting contact with cigarette smoke and taking care of medical conditions such as asthma, diabetes, or heart disease helps to prevent respiratory infections.⁵

Bacterial pathogens that typically cause CAP include Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Staphylococcus aureus, Legionella species, Chlamydia pneumoniae, and Moraxella catarrhalis.⁴ Viral pathogens may also play a role or coexist in patients with CAP.⁴ Empiric treatment should target bacterial infection or coinfection. To date, tests that are accurate or fast enough to determine whether CAP is due solely to a virus are lacking.⁴ Methicillin-resistant S. aureus (MRSA) and Pseudomonas aeruginosa are two multidrug-resistant pathogens with specific treatment recommendations.⁴ The categorization of healthcare-associated pneumonia (HCAP) has been eliminated from the ATS/IDSA guidelines, emphasizing local epidemiology and risk factors to help determine the need to treat multidrug-resistant pathogens.⁴

Table 1

Risk Factors for CAP^6-8

Older age (≥65 years)

Children > 5 years

Smoking (impaired mucociliary clearance

Chronic obstructive pulmonary disease (COPD)

Asthma

Poor oral health

Poor nutritional status

Functional impairment

Environmental exposures (metals, dust, fumes)

Immunosuppressive therapy

Clinical Manifestations and Diagnosis

Clinical Features

Cough, sputum production, and shortness of breath are the most common presenting symptoms among patients who are hospitalized with CAP.⁹ Other potential signs and symptoms include fever, abnormal white blood cell counts, tachypnea, and hypoxemia.⁹

No single feature has sufficient sensitivity or specificity to confirm the diagnosis.¹⁰ One systematic review found that normal vital signs substantially reduce the likelihood of CAP, whereas more specific signs, such as egophony or percussion dullness, strongly increase diagnostic certainty.¹⁰

Diagnosis

The diagnosis of CAP requires a combination of clinical findings and radiographic evidence.¹⁰ A reliable diagnosis occurs when at least two compatible signs or symptoms, including fever or hypothermia, leukocytosis or leukopenia, or new or worsening cough and dyspnea, are present along with a radiographic abnormality (airspace opacity or infiltrate).¹¹ It is important that these findings are explained by pneumonia rather than an alternative diagnosis.¹¹

To date, CAP remains frequently overdiagnosed. Estimates suggest that 10–30% of patients treated for pneumonia do not actually meet clinical and radiologic diagnostic standards.¹² Common mimics include exacerbations of COPD or asthma, acute bronchitis, pulmonary embolism, aspiration syndromes, and even previously undiagnosed malignancies. When clinical and radiologic findings are discordant, additional imaging or further diagnostic evaluation may be warranted.

Radiographic Evidence

A patient’s history and examination findings can be limited, so radiographic imaging is recommended in all patients in whom CAP is suspected.¹³ Radiographic imaging is reviewed in Table 2. Standard chest radiography remains the first-line test. Computed tomography (CT) of the chest is more sensitive and may detect infiltrates that are not visible on plain films.¹³ In one large study, less than half of CT-confirmed opacities were visible on chest radiographs.¹⁴ Computed tomography may also help the care team exclude alternative diagnoses such as pulmonary embolism, malignancy, or aspiration pneumonitis.

Table 2

Radiographic and Imaging Findings in CAP¹³

Imaging Modality	Typical Findings / Notes
Chest radiograph	New alveolar opacities (most common); may also show pleural effusion, cavitary changes, or mass-like lesions
Chest CT	Higher sensitivity than radiograph; detects opacities missed on plain films; useful for ruling out alternative diagnoses (e.g., pulmonary embolism, malignancy, aspiration)
Lung ultrasound	Can approach CT in diagnostic accuracy when performed by trained clinicians; utility is limited by operator dependence

Diagnostic Testing

The Pneumonia Severity Index (PSI) is the preferred clinical prognostic tool to determine the need for hospitalization in adults with CAP, but it should be used in conjunction with clinical judgment, as it may underestimate severity in some cases.¹⁵ The PSI helps to predict the 30-day mortality rate in hospitalized patients with CAP and divides patients into 5 risk classes.¹⁵ Risk classes 1 and 2 can be considered for outpatient treatment, and classes 3-5 qualify for inpatient treatment.¹⁵ The PSI considers sex, age, nursing home status, comorbidities (neoplasm, liver disease, congestive heart failure, cerebrovascular disease, and renal disease), physical examination findings, and laboratory and radiographic findings.¹⁶ Physical examination findings include altered mental status, respiratory rate, systolic blood pressure, temperature, and pulse.^15,16 Laboratory and radiographic findings include arterial pH, blood urea nitrogen, sodium, glucose, hematocrit, partial pressure of arterial oxygen, and pleural effusion.^15,16 The PSI indicates which setting the patient should be treated in, not the level of care needed. Clinicians are encouraged to use the PSI over the CURB-65.⁴ The CURB-65 may give a false-positive hospital admission rate and is based on confusion, urea level, respiration rate, blood pressure, and age 65 or over.⁴

The 2007 IDSA/ATS CAP guidelines outline criteria for severe pneumonia requiring ICU admission. All patients requiring treatment with vasopressors for hypotension and mechanical ventilation for respiratory failure need ICU-level care.¹⁷ Criteria for defining Severe CAP are as follows:^4,17

Either one major criterion or three or more minor criteria

Minor Criteria: Respiratory rate ≥30 breaths/min, arterial oxygen partial pressure (PaO2)/fractional inspired oxygen (Fi02) ratio ≤ 250, multilobar infiltrates, confusion/disorientation, uremia, leukopenia due to infection alone, thrombocytopenia, hypothermia, or hypotension requiring aggressive fluid resuscitation

Major Criteria: Septic shock with the need for vasopressors or respiratory failure requiring mechanical ventilation.

Sputum gram stains and cultures, as well as pretreatment blood cultures, should be obtained in patients who are in the hospital setting and are classified as at least one of the following:^4,17

Severe CAP (especially if intubated)

Being empirically treated for MRSA or P. aeruginosa

Previously infected with MRSA or P. aeruginosa

Hospitalized and received IV antibiotics in the last 90 days.

Mechanism of Action for Empiric Antibiotic Choices

The selection of appropriate empiric antibiotic therapy is a cornerstone of effective treatment for CAP, aiming to address the most common pathogens while minimizing the risk of complications, such as antimicrobial resistance. The choice of antibiotics should be informed by their mechanisms of action, and understanding the pharmacodynamics and spectrum of activity of key antibiotics, such as beta-lactams, macrolides, and fluoroquinolones, is essential for clinicians to tailor treatment based on the severity of the infection, local resistance patterns, and the patient's individual risk factors.⁴ This section describes the mechanisms of action behind these empiric agents, providing insights into their effectiveness and how they work synergistically in combination therapies to optimize patient outcomes.

Beta Lactams

Beta-lactam antibiotics, such as penicillins and cephalosporins, disrupt the final stage of bacterial cell wall synthesis and inhibit peptidoglycan synthesis, a fundamental component of the cell wall that causes cell lysis.¹⁸ The addition of a beta-lactamase inhibitor, such as clavulanic acid, sulbactam, or tazobactam, helps to protect the penicillin from enzymatic deactivation.¹⁸

Penicillins used for CAP include amoxicillin, amoxicillin-clavulanic acid, ampicillin-sulbactam, and piperacillin-tazobactam.⁴ Penicillins may require renal dose adjustment.¹⁸ Allergic or hypersensitivity reactions are the most common adverse reactions in patients taking penicillin.¹⁸ Gastrointestinal adverse reactions such as nausea, vomiting, diarrhea, and abdominal pain may occur, especially when administered orally.¹⁸

Under the ATS/IDSA guidelines, cephalosporins used to treat CAP include cefuroxime, cefpodoxime, cefotaxime, ceftriaxone, ceftaroline, ceftazidime, and cefepime.^19-21 These medications may require dose adjustments due to renal impairment.⁴ Patients should be monitored for superinfection, including candidiasis, C. difficile-associated diarrhea, or pseudomembranous colitis.^19-21 Dermatologic reactions have been reported in approximately 1 to 3% of cephalosporin treatment courses.²²

Doxycycline

Doxycycline is a tetracycline antibiotic that is generally bacteriostatic.²³ It binds to the 30S ribosomal subunit of bacteria and blocks the binding of transfer RNA to the messenger RNA, thereby inhibiting bacterial protein synthesis.²³ Doxycycline may be used in patients with poor renal function due to its limited renal clearance.²³ Common adverse reactions to doxycycline include diarrhea, nausea, vomiting, and dyspepsia.²³ These common gastrointestinal side effects may be reduced by administering with food.²³ Microbial overgrowth and superinfection may also occur in patients taking doxycycline.²³ Care teams should counsel patients about the increased risk of photosensitivity.²³

Macrolide

Macrolides, such as azithromycin and clarithromycin, inhibit bacterial growth by suppressing protein synthesis.^24,25 Macrolides exhibit reversible binding to the 50S ribosomal subunits, which induces the dissociation of transfer RNA from the ribosome during the elongation phase.^24,25 Renal dosing adjustments may be needed for macrolide antibiotics. Gastrointestinal intolerance is one of the primary adverse effects seen with this class of medications.^24,25 They may also cause QT prolongation.²⁶ Microbial overgrowth and superinfection should also be monitored in patients taking macrolides.^24,25 Macrolides should not be used if the local resistance rate is greater than 25%.⁴

Respiratory Fluoroquinolones

Respiratory fluoroquinolones used to treat CAP include levofloxacin, moxifloxacin, and gemifloxacin.⁴ These medications inhibit bacterial DNA gyrase and topoisomerase IV, interrupting DNA replication, repair, and transcription.^27-29 These agents may require dose adjustments in patients with renal impairment.^27-29 Additionally, they have boxed warnings for tendinopathy, myasthenia gravis, and neurotoxicity.^27-29 Potential neurotoxic effects include central nervous system effects and peripheral neuropathy.^27-29

This class should be used cautiously in patients with epilepsy, preexisting CNS disorders, and patients who have recently had a stroke.^27-29 Caution is also warranted in patients with prolonged QT intervals and photosensitivity.^27-29 Although there is concern about adverse events associated with fluoroquinolones, the CAP guidelines note that therapy is justified for adults with CAP and comorbidities who are managed in the outpatient setting.^27-29 Benefits that outweigh the risks of fluoroquinolones in this setting include low rates of resistance in common bacterial causes of CAP, coverage of typical and atypical organisms, the convenience of monotherapy, oral bioavailability, and the relatively low rate of serious adverse effects.⁴

Vancomycin

Vancomycin exerts its effect by binding to the precursor units of bacterial cell walls, thereby inhibiting their synthesis.³⁰ This antibiotic is a bactericidal agent that exhibits concentration-independent killing. Vancomycin is a useful agent for MRSA-associated CAP.³⁰ Patients being administered vancomycin should be monitored for renal toxicity and ototoxicity.³⁰ Vancomycin that is given by rapid infusion may cause a histamine-release reaction that is characterized by flushing of the face, neck, upper body, arms, and/or back.³⁰ This vancomycin infusion reaction may result in anaphylactic reactions and may also cause pain and muscle spasms.³⁰ Patients receiving IV vancomycin may also experience general adverse reactions, such as fever and chills. Microbial overgrowth should also be monitored during vancomycin therapy.³⁰

Linezolid

Linezolid is an oxazolidinone that inhibits bacterial protein synthesis by interfering with translation.³¹ It binds to the bacterial 23S ribosomal RNA of the 50S subunit, which prevents the formation of a functional 70S initiation complex, which prevents bacteria from multiplying.³¹ Linezolid is bactericidal against many streptococcal strains and bacteriostatic against staphylococci and enterococci.³¹

Gastrointestinal adverse reactions are commonly reported (diarrhea, nausea, vomiting, dysgeusia, and abdominal pain) in patients taking linezolid. Headache is one of the most common non-gastrointestinal side effects reported.³¹ Microbial overgrowth should be monitored in patients receiving linezolid, and thrombocytopenia should be monitored in patients receiving therapy for more than 2 weeks and in those with severe renal impairment.³¹ Postmarketing reports have included peripheral and optic neuropathy.³¹ Linezolid therapy should be avoided, if possible, in patients also taking selective serotonin reuptake inhibitors. If necessary and the benefits outweigh the risks, linezolid may be used in these patients with close monitoring for signs and symptoms of serotonin syndrome.³¹ The serotonergic antidepressant should be discontinued during this time and should not be restarted until at least 24 hours have passed since the last dose of linezolid. Linezolid should not be prescribed if a patient is taking a monoamine oxidase inhibitor (MAOI) or within two weeks of MAOI therapy.³¹

Pause and Ponder

What is the most frequent side effect you have seen with antibiotics for treating CAP, and how did you counsel the patient?

Initial Treatment Regimens for Outpatients with CAP

With a solid understanding of empiric antibiotic choices, the next step in managing CAP is to select the most appropriate treatment regimen, particularly in outpatient settings. The initial treatment regimen for outpatients is guided by the severity of the illness, comorbidities, and the local prevalence of resistant pathogens.⁴ An effective treatment strategy requires an interprofessional care team approach, as collaboration between physicians, pharmacists, nurses, and other healthcare providers ensures that therapy is not only appropriate but also tailored to the individual patient. Together, the team ensures a comprehensive, patient-centered approach to CAP management, promoting timely recovery and minimizing the risk of complications.

Standard regimens for individuals with no comorbidities or risk factors for MRSA or Pseudomonas aeruginosa include one of the following:⁴

Amoxicillin 1 gram three times daily

Doxycycline 100 mg twice daily

Macrolide (if local pneumococcal resistance is <25%)

Azithromycin 500 mg on the first day, then 250 mg thereafter

Clarithromycin 500 mg twice daily

Clarithromycin ER 1000 mg daily

Initial treatment for patients with comorbidities includes one of these two options.⁴

Option 1: Combination therapy with Amoxicillin/clavulanate or cephalosporin AND macrolide or doxycycline

Amoxicillin/Clavulanate options:

Amoxicillin/Clavulanate 500 mg/125 mg three times daily

Amoxicillin/Clavulanate 875 mg/125 mg or 2,000 mg/125 mg twice daily

Cephalosporin options:

Cefpodoxime 200 mg twice daily

Cefuroxime 500 mg twice daily

Macrolide options:

Azithromycin 500 mg on the first day, then 250 mg daily

Clarithromycin 500 mg twice daily

Clarithromycin ER 1000 mg daily

Doxycycline 100 mg twice daily

Option 2: Monotherapy with respiratory fluoroquinolone

Levofloxacin 750 mg daily

Moxifloxacin 400 mg daily

Gemifloxacin 320 mg daily

Comorbidities include chronic heart, lung, liver, renal disease, diabetes, alcoholism, malignancy, or asplenia.⁴ Broader-spectrum treatment is recommended in these patients to help improve outcomes and combat the risk of antibiotic resistance based on previous contact with the healthcare system or antibiotic exposure.⁴

Pneumonia Essentials: Match and Master

Pause for a Knowledge Check and Match the Term in Column A to the Definition in Column B. The answers for this Check and Match the Term are located after the course summary.

Column A	Column B
Community-Acquired Pneumonia (CAP)	A drug class that disrupts the final stage of bacterial cell wall synthesis
Pneumonia Severity Index (PSI)	B. Inhibits bacterial growth by suppressing protein synthesis
Beta-lactam antibiotics	C. Infection of the lungs acquired outside of the hospital setting
Risk factors for pneumonia	D. Tool used to determine hospitalization need and predict 30-day mortality
Macrolide antibiotics	E. Advanced age, young children, chronic illness, smoking

Treatment Regimens for Hospitalized Patients with CAP

Inpatient treatment regimens are based on the severity of the patient’s pneumonia.⁴ Table 3 provides initial treatment strategies for inpatients with CAP.

Table 3

ATS/IDSA Initial Treatment Strategies

for Inpatients with CAP⁴

	Non-severe inpatient pneumonia	Severe Inpatient Pneumonia
Standard regimen	Beta-Lactam PLUS macrolide or respiratory fluoroquinolone *Can use doxycycline 100 mg twice daily in combination with a beta-lactam if the patient has a contraindication to macrolide or fluoroquinolone	Beta-Lactam PLUS Macrolide OR Beta-lactam PLUS fluoroquinolone
Prior Respiratory Isolation of MRSA:	Add MRSA Coverage (Vancomycin 15 mg/kg every 12 hours adjusted based on renal function and levels OR linezolid 600 mg every 12 hours). Obtain a PCR to allow de-escalation or confirmation of the need for continued therapy.	Same as non-severe
Prior Respiratory Isolation of Pseudomonas aeruginosa	Add coverage for P. aeruginosa: Piperacillin-tazobactam 4.5 grams every 6 hours, cefepime 2 grams every 8 hours, ceftazidime 2 grams every 8 hours, meropenem 1 gram every 8 hours, imipenem 500 mg every 6 hours, or aztreonam 2 grams every 8 hours. Obtain cultures to assess therapy	Same as non-severe
Recent hospitalization, parenteral antibiotics, and locally validated risk factors for MRSA	Obtain cultures but withhold MRSA coverage unless cultures are positive. If rapid nasal PCR is available, withhold additional empiric therapy against MRSA and adjust therapy based on culture.	Add MRSA Coverage (Vancomycin 15 mg/kg every 12 hours adjusted based on renal function and levels OR linezolid 600 mg every 12 hours) and obtain nasal PCR and cultures to assess therapy.
Beta-lactam therapy: Ampicillin+sulbactam 1.5-3 grams every 6 hours Cefotaxime 1-2 grams every 8 hours Ceftriaxone 1-2 grams daily Ceftaroline 600 mg every 12 hours Macrolide therapy: Azithromycin 500 mg once daily Clarithromycin 500 mg twice daily Respiratory Fluoroquinolone Levofloxacin 750 mg daily Moxifloxacin 400 mg daily MRSA Coverage: Vancomycin 15 mg/kg every 12 hours, adjusted based on renal function and levels Linezolid 600 mg every 12 hours P. aeruginosa coverage: Piperacillin-tazobactam 4.5 grams every 6 hours Cefepime 2 grams every 8 hours Ceftazidime 2 grams every 8 hours Imipenem 1 gram every 8 hours Aztreonam 2 grams every 8 hours

Treatment Considerations for Inpatients and Outpatients

The duration of antibiotic therapy should be guided by clinical stability.⁴ Clinical stability includes resolution of vital sign abnormalities (heart rate, respiratory rate, blood pressure, oxygen saturation, and temperature), ability to eat, and normal mentation.⁴ Antibiotic therapy should last for no less than 5 days and until the patient achieves stability. Most studies support a 5-day course of treatment in the outpatient setting; however, in some cases, a longer duration (7 to 10 days) is indicated. Patients suspected or proven to have MRSA or P. aeruginosa CAP should be treated for 7 days.⁴

Patients who have had recent exposure to one antibiotic class should receive subsequent treatment with an antibiotic from a different class to help reduce the risk of bacterial resistance to the initial treatment.⁴ The routine use of corticosteroids in adults hospitalized with CAP is not currently recommended.⁴ The CAP guidelines endorse the Surviving Sepsis Campaign recommendations to use steroids in patients with septic shock refractory to adequate fluid resuscitation and vasopressor support with CAP.³² Increases in hyperglycemia requiring therapy and possible higher secondary infection rates are side effects associated with corticosteroids.^33,34 Clinical judgment should be used, and patients presenting with comorbid diseases (COPD, asthma, autoimmune disease) may require corticosteroids.^33,34

Table 4

Summary of ATS CAP Recommendations²

Clinical Scenario	Recommendation
Outpatients without comorbidities, CAP confirmed, respiratory virus positive	Do not prescribe empiric antibiotics
Inpatients with non-severe CAP, respiratory virus positive	Prescribe empiric antibiotics
Inpatients with severe CAP, respiratory virus positive	Prescribe empiric antibiotics (due to concern for bacterial–viral co-infection)
Outpatients with CAP who reach clinical stability	Treat with <5 days of antibiotics (minimum 3 days)
Inpatients with non-severe CAP who reach clinical stability	Treat with <5 days of antibiotics (minimum 3 days)
Inpatients with severe CAP who reach clinical stability	Treat with ≥5 days of antibiotics
Inpatients with non-severe CAP	Do not administer systemic corticosteroids
Inpatients with severe CAP	Inpatients with severe CAP

Patients who test positive for influenza and have clinical and radiographic evidence of CAP should be treated for both conditions as they may occur concurrently.⁴ Patients who test positive for influenza should receive anti-influenza treatment such as oseltamivir.⁴ Anti-influenza treatment that occurs within 2 days of symptom onset or hospitalization have shown the best results; however, benefits may be seen up to 4 or 5 days after symptoms begin.^35,36 Antinfluenza agents are most effective when administered early and can reduce symptom duration and lower complication risk in patients with influenza.^37,38 Antibacterial therapy would follow the recommendations listed above.

Antibacterial Therapy, De-escalation, and Duration in CAP

The optimal treatment approach to antibacterial therapy in CAP balances efficacy with stewardship principles. Clinical stability should guide treatment duration, with stability defined as normalization of vital signs (temperature, heart rate, respiratory rate, blood pressure, and oxygen saturation), restoration of normal mentation, and ability to tolerate oral intake.⁴ Antibiotic therapy should last for a minimum of five days and continue until stability is achieved. For most patients treated in the outpatient setting, a five-day course is sufficient; however, longer durations (7–10 days) may be warranted in cases of slow clinical response, complications such as empyema, or infections caused by Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa (≥7 days recommended). ⁴

Recent evidence suggests that shorter courses may be safe and effective in selected patients.³⁹ A 2021 randomized clinical trial of 310 hospitalized patients with non-severe CAP demonstrated that a three-day course of β-lactam therapy was noninferior to an eight-day course when patients achieved complete clinical stability by hospital day 3. About half of inpatients with non-severe CAP reach stability by day 3, and these patients may safely discontinue therapy after three days.³⁹ Conversely, patients who take longer to stabilize should receive at least five days of therapy. Patients with severe disease, complications, or resistant pathogens typically require longer treatment courses.^4,39

Antibacterial de-escalation is another key stewardship strategy. This includes discontinuing antibiotics when bacterial infection is excluded, narrowing from empiric broad-spectrum to targeted therapy once culture results are available, or switching from intravenous to oral therapy as soon as the patient can tolerate oral intake. A retrospective study found that patients who were switched from IV to PO medications early had fewer total days on antibiotics, a shorter length of stay, and lower hospital costs with large increases in 14-day in-hospital mortality.⁴⁰ Oral step-down options for patients without resistant organisms include amoxicillin/clavulanate, oral cephalosporins (e.g., cefpodoxime), or azithromycin regimens totaling 1,500 mg (e.g., 500 mg daily for three days or 500 mg on day 1 followed by 250 mg daily for four days).⁴ Patients recently exposed to a specific class of antibiotics should receive a different class to minimize the risk of resistance.⁴ Antibacterial therapy should also be tailored to comorbid conditions and local resistance patterns, with stewardship interventions applied wherever possible.

Summary

Community-acquired pneumonia is associated with high morbidity and mortality. Some patients can be treated in the outpatient setting, while others may require inpatient hospitalization. Patients with severe CAP require care in the ICU. Several different treatment options for CAP take into account patient allergies and intolerances, as well as potential causes of infection. Cultures should be obtained in hospitalized patients, and therapy may be adjusted based on results.

Answers to Pneumonia Essentials: Match and Master:

1-C, 2-D, 3-B, 4-E, 5-B

Column A	Column B
Community-Acquired Pneumonia (CAP)	A drug class that disrupts the final stage of bacterial cell wall synthesis
Pneumonia Severity Index (PSI)	B. Inhibits bacterial growth by suppressing protein synthesis
Beta-lactam antibiotics	C. Infection of the lungs acquired outside of the hospital setting
Risk factors for pneumonia	D. Tool used to determine hospitalization need and predict 30-day mortality
Macrolide antibiotics	E. Advanced age, young children, chronic illness, smoking

References

National Institutes of Health. National Heart, Lung, and Blood Institute. Pneumonia. What Is Pneumonia? NIH-NHLBI. Last updated on March 24, 2022. Accessed September 13, 2025. http://www.nhlbi.nih.gov/health/health-topics/topics/pnu

Infectious Diseases Society of America. CAP CLINICAL PATHWAY. Updated as of November 1, 2023. Accessed September 13, 2025. https://www.idsociety.org/globalassets/idsa/practice-guidelines/community-acquired-pneumonia-in-adults/cap-clinical-pathway-final-online.pdf

McLaughlin JM, Khan FL, Thoburn EA, Isturiz RE, Swerdlow DL. Rates of hospitalization for community-acquired pneumonia among US adults: A systematic review. Vaccine. 2020;38(4):741-751. doi:10.1016/j.vaccine.2019.10.101

Metlay JP, Waterer GW, Long AC, et al. Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019;200(7):e45-e67. doi:10.1164/rccm.201908-1581ST

Centers for Disease Control and Prevention. Pneumonia. Pneumonia. Prevention and Control. CDC. August 21, 2024. Accessed September 13, 2025. https://www.cdc.gov/pneumonia/prevention/?CDC_AAref_Val=https://www.cdc.gov/pneumonia/prevention.html

Centers for Disease Control and Prevention. Risk Factors for Pneumonia. CDC. October 17, 2023. Accessed September 13, 2025. https://www.cdc.gov/pneumonia/risk-factors/index.html

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