eMedicine Specialties > Infectious Diseases > Bacterial Infections

Pseudomonas aeruginosa Infections: Differential Diagnoses & Workup

Author: Samer Qarah, MD, Pulmonary Critical Care Consultant, Department of Internal Medicine, Division of Pulmonary and Critical Care, The Brooklyn Hospital Center and Cornell University
Coauthor(s): Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital; Pratibha Dua, MD, MBBS, Staff Physician, Department of Internal Medicine, The Brooklyn Hospital Center; Klaus-Dieter Lessnau, MD, FCCP, Clinical Assistant Professor of Medicine, New York University School of Medicine; Medical Director, Pulmonary Physiology Laboratory, Director of Research in Pulmonary Medicine, Department of Medicine, Section of Pulmonary Medicine, Lenox Hill Hospital; Tarun Madappa, MD, MPH, Pulmonary Fellow, Section of Pulmonary Medicine, Lenox Hill Hospital
Contributor Information and Disclosures

Updated: Mar 17, 2008

Differential Diagnoses

Acute Respiratory Distress Syndrome
Pneumonia, Viral
Pneumococcal Infections
Sepsis, Bacterial
Pneumocystis Carinii Pneumonia
Septic Shock
Pneumonia, Aspiration
Stenotrophomonas Maltophilia
Pneumonia, Bacterial
Pneumonia, Community-Acquired
Pneumonia, Fungal

Other Problems to Be Considered

AIDS
Malignant otitis media
Infectious complications of diabetes
Jacuzzi (hot tub) itch

Workup

Laboratory Studies

  • A CBC count may reveal leukocytosis with a left shift and bandemia. In patients with hematologic malignancy or status postchemotherapy, leukopenia with neutropenia is expected. Leukopenia is a poor prognostic indicator.
  • Blood cultures  
    • Obtain at least 2 sets of blood cultures (2 aerobic, 2 anaerobic bottles) from different sites.
    • Positive results on blood culture in the absence of extracardiac sites of infection may indicate pseudomonal endocarditis. However, bacteremia may complicate intravenous catheter infections, urinary tract instrumentation, trauma, and surgery in the absence of endocarditis.
  • In UTI, urinalysis is helpful in determining a diagnosis.
  • In pneumonia, sputum and respiratory secretions should be cultured. However, the isolation of Pseudomonas from sputum and tracheal secretions might indicate airway colonization. The poor sensitivity and specificity of sputum in determining the bacterial cause of pneumonia in patients who are mechanically ventilated has led to greater use of quantitative cultures obtained from protected bronchoalveolar lavage and protected specimen brushings. Blood gas analysis to evaluate for hypoxia or hypercarbia should also be performed in patients with pneumonia.
  • Obtain wound and burn cultures and cultures from other body fluids and secretions according to the clinical scenario. To aid in diagnosis, obtaining burn wound biopsies with quantitative bacterial cultures is recommended. A bacterial count of greater than 105 organisms per gram of tissue is diagnostic of a burn wound infection.
  • Obtain Gram stain and culture of cerebrospinal fluid if meningitis is suspected.

Imaging Studies

  • Chest radiography  
    • Abnormalities observed in pseudomonal pneumonia depend on the pathogenesis of the infections. In primary pseudomonal pneumonia, in which aspiration of infected secretions results in  pneumonia, the chest radiograph often reveals bilateral bronchopneumonia consisting of nodular infiltrates with or without pleural effusion. Lobar pneumonia is uncommon.
    • Early pulmonary vascular congestion is found in patients with bacteremic pseudomonal pneumonia and rapidly progresses to pulmonary edema and necrotizing bronchopneumonia. Within 48-72 hours, the radiograph demonstrates a mixture of alveolar and interstitial infiltrates, and cavitation may be present.
  • Triple-phase bone scan may be useful in patients with suspected skeletal infection, although many would preferentially rely on MRI.
  • BrainCT scan or MRI allows for evaluation of patients suspected of having a pseudomonal brain abscess.
  • Renal ultrasonography is useful in evaluating patients suspected of having a perinephric abscess complicating UTI.
  • Echocardiography should be considered in patients with positive blood culture findings in whom endocarditis is suspected. Normal transthoracic echocardiography findings do not rule out endocarditis in patients in whom clinical suspicion is high. Transesophageal echocardiography should then be considered.

Other Tests

  • Gram stain of respiratory secretions and cerebrospinal fluid
  • Fluorescein staining and slit-lamp examination of the cornea for keratitis

Procedures

  • Procedures indicated for pseudomonal infections depend on the clinical picture and the site of infection.
  • Flexible fiberoptic bronchoscopy with bronchoalveolar lavage or bronchial brushing may be useful in pneumonia. Pleural effusions may require thoracocentesis.
  • Lumbar puncture with cell count and cultures is indicated in suspected pseudomonal meningitis.

Histologic Findings

Pseudomonas infection causes necrotizing inflammation. Histologically, gram-negative rods are observed in the walls of blood vessels, causing coagulation necrosis, along with thrombosis and hemorrhage.

More on Pseudomonas aeruginosa Infections

Overview: Pseudomonas aeruginosa Infections
Differential Diagnoses & Workup: Pseudomonas aeruginosa Infections
Treatment & Medication: Pseudomonas aeruginosa Infections
Follow-up: Pseudomonas aeruginosa Infections
References
Further Reading
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References

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  2. Textbook of Bacteriology. Todar's Online Textbook of Bacteriology [serial online]. Accessed 29/12/07. Available at www.textbookofbacteriology.net..

  3. Abuqaddom AI, Darwish RM, Muti H. The effects of some formulation factors used in ophthalmic preparations on thiomersal activity against Pseudomonas aeruginosa and Staphylococcus aureus. J Appl Microbiol. 2003;95(2):250-5. [Medline].

  4. Bliziotis IA, Samonis G, Vardakas KZ, Chrysanthopoulou S, Falagas ME. Effect of aminoglycoside and beta-lactam combination therapy versus beta-lactam monotherapy on the emergence of antimicrobial resistance: a meta-analysis of randomized, controlled trials. Clin Infect Dis. Jul 15 2005;41(2):149-58. [Medline].

  5. Chamot E, Boffi El Amari E, Rohner P, Van Delden C. Effectiveness of combination antimicrobial therapy for Pseudomonas aeruginosa bacteremia. Antimicrob Agents Chemother. Sep 2003;47(9):2756-64. [Medline].

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  21. [Best Evidence] Paul M, Silbiger I, Grozinsky S, Soares-Weiser K, Leibovici L. Beta lactam antibiotic monotherapy versus beta lactam-aminoglycoside antibiotic combination therapy for sepsis. Cochrane Database Syst Rev. 2006;(1):CD003344. [Medline].

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Further Reading

For additional information, see Medscape’s Pneumonia Resource Center, Sepsis Resource Center, and Cystic Fibrosis Resource Center.

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Keywords

Pseudomonas aeruginosa, P aeruginosa, Pseudomonas aeruginosa infection, P aeruginosa infection, swimmer's ear, Shanghai fever, tropical immersion foot syndrome, green nail syndrome, green foot, Pseudomonas hot-foot syndrome, nosocomial infections, nosocomial pneumonia, urinary tract infection, UTI, bacteremia, Pseudomonas aeruginosa pneumonia, Pseudomonas aeruginosa endocarditis, vertebral osteomyelitis, pseudomonal infection, pseudomonal pneumonia, pseudomonal endocarditis, cystic fibrosis, pseudomonal bacteremia, chronic otitis media, ecthyma gangrenosum, burn wound infection, neutropenia

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Contributor Information and Disclosures

Author

Samer Qarah, MD, Pulmonary Critical Care Consultant, Department of Internal Medicine, Division of Pulmonary and Critical Care, The Brooklyn Hospital Center and Cornell University
Samer Qarah, MD is a member of the following medical societies: American College of Critical Care Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital
Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Pratibha Dua, MD, MBBS, Staff Physician, Department of Internal Medicine, The Brooklyn Hospital Center
Pratibha Dua, MD, MBBS is a member of the following medical societies: American Medical Association
Disclosure: Nothing to disclose.

Klaus-Dieter Lessnau, MD, FCCP, Clinical Assistant Professor of Medicine, New York University School of Medicine; Medical Director, Pulmonary Physiology Laboratory, Director of Research in Pulmonary Medicine, Department of Medicine, Section of Pulmonary Medicine, Lenox Hill Hospital
Klaus-Dieter Lessnau, MD, FCCP is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, American Medical Association, American Society for Artificial Internal Organs, American Thoracic Society, Physicians for Social Responsibility, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

Tarun Madappa, MD, MPH, Pulmonary Fellow, Section of Pulmonary Medicine, Lenox Hill Hospital
Tarun Madappa, MD, MPH is a member of the following medical societies: American College of Chest Physicians and American Thoracic Society
Disclosure: Nothing to disclose.

Medical Editor

Thomas J Marrie, MD, Chair, Professor, Department of Medicine, Division of Infectious Diseases, University of Alberta College of Medicine
Thomas J Marrie, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American Society for Microbiology, Canadian Infectious Disease Society, and Royal College of Physicians and Surgeons of Canada
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

John L Brusch, MD, FACP, Assistant Professor of Medicine, Harvard Medical School; Consulting Staff, Department of Medicine and Infectious Disease Service, Cambridge Health Alliance
John L Brusch, MD, FACP is a member of the following medical societies: American College of Physicians and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

CME Editor

Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Chief Editor

Michael Stuart Bronze, MD, Professor, Stewart G Wolf Chair in Internal Medicine, Department of Medicine, University of Oklahoma Health Science Center
Michael Stuart Bronze, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physician Executives, American College of Physicians, American College of Physicians-American Society of Internal Medicine, American Federation for Clinical Research, American Medical Association, American Society for Microbiology, Association of Professors of Medicine, Association of Program Directors in Internal Medicine, Infectious Diseases Society of America, Oklahoma State Medical Association, and Southern Society for Clinical Investigation
Disclosure: Nothing to disclose.

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