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Proteus Infections Workup

  • Author: Gus Gonzalez, MD; Chief Editor: Michael Stuart Bronze, MD  more...
 
Updated: Oct 08, 2015
 

Laboratory Studies

Proteus organisms are easily recovered through routine laboratory cultures. Most strains are lactose-negative and demonstrate characteristic swarming motility on agar plates. Any positive culture result from an otherwise sterile area should be considered an acute infection if clinical signs and symptoms are present.

After 24 hours, this inoculated MacConkey agar cul After 24 hours, this inoculated MacConkey agar culture plate cultivated colonial growth of gram-negative, rod-shaped, and facultatively anaerobic Proteus vulgaris bacteria. Courtesy of the CDC.

UTIs in symptomatic patients have traditionally been defined by recovering bacteria in large numbers (ie, >100,000 colony-forming units [CFUs]/mL) on examination. Bacterial counts of less than 100,000 CFUs/mL may indicate infection in urine samples, especially if obtained directly from the ureters or renal pelvis, whereas specimens from suprapubic catheters usually have bacterial counts greater than 100,000 CFUs/mL. However, even small numbers of organisms may be of true clinical significance in symptomatic patients (eg, women with the urethral syndrome).

Microscopic bacteriuria is best evaluated through uncentrifuged Gram staining of the urine. Microscopic bacteriuria is found in 90% of cases when bacterial counts exceed 100,000 CFUs/mL. Detection by microscopy confirms infection, but absence does not exclude infection. Pyuria is demonstrated in nearly all acute bacterial infections, but its absence calls the diagnosis into question. The leukocyte esterase dipstick test is a useful alternative to microscopic examination, but this method is less sensitive than microscopy.

Persistently alkaline urine with a positive Proteus culture finding should prompt an examination for renal calculi.

Although cultures are the most definitive way of confirming an acute Proteus infection, they are often prohibitively expensive and take time for complete identification. Cultures are most effective when patients do not respond to empiric therapy or when they have recurrent symptoms.

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Imaging Studies

Ultrasonography of the kidneys or a CT scan should be considered as part of a workup for Proteus infection of the urinary tract that does not resolve quickly with antimicrobial therapy. Calices and/or perinephric abscesses should be excluded.

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Contributor Information and Disclosures
Author

Gus Gonzalez, MD Medical Oncologist, The Center for Cancer and Blood Disorders

Gus Gonzalez, MD is a member of the following medical societies: American College of Physicians-American Society of Internal Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Michael Stuart Bronze, MD David Ross Boyd Professor and Chairman, Department of Medicine, Stewart G Wolf Endowed Chair in Internal Medicine, Department of Medicine, University of Oklahoma Health Science Center; Master of the American College of Physicians; Fellow, Infectious Diseases Society of America

Michael Stuart Bronze, MD is a member of the following medical societies: Alpha Omega Alpha, American Medical Association, Oklahoma State Medical Association, Southern Society for Clinical Investigation, Association of Professors of Medicine, American College of Physicians, Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Aaron Glatt, MD Chief Administrative Officer, Executive Vice President, Mercy Medical Center, Catholic Health Services of Long Island

Aaron Glatt, MD is a member of the following medical societies: American College of Chest Physicians, American Association for Physician Leadership, American College of Physicians, American College of Physicians-American Society of Internal Medicine, American Medical Association, American Society for Microbiology, American Thoracic Society, American Venereal Disease Association, Infectious Diseases Society of America, International AIDS Society, Society for Healthcare Epidemiology of America

Disclosure: Nothing to disclose.

Chief Editor

Michael Stuart Bronze, MD David Ross Boyd Professor and Chairman, Department of Medicine, Stewart G Wolf Endowed Chair in Internal Medicine, Department of Medicine, University of Oklahoma Health Science Center; Master of the American College of Physicians; Fellow, Infectious Diseases Society of America

Michael Stuart Bronze, MD is a member of the following medical societies: Alpha Omega Alpha, American Medical Association, Oklahoma State Medical Association, Southern Society for Clinical Investigation, Association of Professors of Medicine, American College of Physicians, Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Acknowledgements

Rhett L Jackson, MD Associate Professor and Vice Chair for Education, Department of Medicine, Director, Internal Medicine Residency Program, University of Oklahoma College of Medicine; Assistant Chief, Medicine Service, Oklahoma City Veterans Affairs Hospital

Rhett L Jackson, MD is a member of the following medical societies: American College of Physicians-American Society of Internal Medicine and American Medical Association

Disclosure: Nothing to disclose.

Kelley Struble, DO Fellow, Department of Infectious Diseases, University of Oklahoma College of Medicine

Kelley Struble, DO is a member of the following medical societies: American College of Physicians and Infectious Diseases Society of America

Disclosure: Nothing to disclose.

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After 24 hours, this inoculated MacConkey agar culture plate cultivated colonial growth of gram-negative, rod-shaped, and facultatively anaerobic Proteus vulgaris bacteria. Courtesy of the CDC.
 
 
 
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