eMedicine Specialties > Infectious Diseases > Bacterial Infections

Bacteroides Infection: Differential Diagnoses & Workup

Author: Itzhak Brook, MD, MSc, Professor, Department of Pediatrics, Georgetown University School of Medicine
Contributor Information and Disclosures

Updated: Oct 29, 2009

Workup

Laboratory Studies

  • Collection of specimens of anaerobic bacteria is important because documentation of an anaerobic infection is through culture of organisms from the infected site. Appropriate documentation of anaerobic infection requires proper collection of appropriate specimens, expeditious transportation, and careful laboratory processing.
    • Specimens must be obtained free of contamination. Inadequate techniques or media can lead to missing the presence of anaerobic bacteria or the assumption that only aerobic organisms are present in a mixed infection.
    • Because anaerobes are present on skin and mucous membranes, even minimal contamination with normal florae can be misleading.
    • Unacceptable or inappropriate specimens can yield normal florae and, therefore, have no or little diagnostic value.
  • Appropriate materials should be obtained by using techniques that bypass the normal florae.
    • Direct-needle aspiration is the best method of obtaining a culture; the use of swabs is much less desirable.
      • Specimens obtained from normally sterile sites, such as blood or spinal, joint, or peritoneal fluids, are collected after thorough skin decontamination.
      • Two approaches are used to culture the maxillary sinus following sterilization of the canine fossa or the nasal vestibule, via either the canine fossa or the inferior meatus.
      • Urine is collected by percutaneous suprapubic bladder aspiration.
      • Other specimens can be collected from abscess contents, from deep aspirates of wounds, and via special techniques, such as transtracheal aspirates or direct lung puncture.
      • Specimens of the lower respiratory tract are difficult to obtain without contamination with indigenous florae. Double-lumen catheter bronchial brushing and bronchoalveolar lavage, cultured quantitatively, can be useful.
      • Culdocentesis fluid obtained after decontamination of the vagina is acceptable.
    • Transportation of specimens should be prompt unless transport devices are available. Transport devices generally contain oxygen-free environments provided by a mixture of carbon dioxide, hydrogen, and nitrogen, plus an aerobic condition indicator. Specimens should be placed into an anaerobic transporter as soon as possible.
  • Liquid or tissue specimens are always preferred to swabs.
    • Liquid specimens are inoculated into an anaerobic transport vial or a syringe and a needle.
    • All air bubbles are expelled from the syringe. Insertion of the needle tip into a sterile rubber stopper is no longer recommended. Because air gradually diffuses through the plastic syringe wall, specimens should be processed in less than 30 minutes.
  • Swabs are placed in sterilized tubes that contain carbon dioxide or prereduced anaerobically sterile Carey and Blair semisolid media.
  • Tissue specimens can be transported in an anaerobic jar or in a sealed plastic bag rendered anaerobic.
  • Gram stain of a smear of the specimen provides important preliminary information regarding the types of organisms present, helps determine appropriate initial therapy, and serves as a quality control.
  • Cultures should be immediately placed under anaerobic conditions and should be incubated for 48 hours or longer. An additional 36-48 hours is generally required for species- or genus-level identification by using biochemical tests. Kits that contain these tests are commercially available.2
  • A rapid enzymatic test enables identification after only 4 hours of aerobic incubation.
  • Gas-liquid chromatography of metabolites is often used.
  • Nucleic acid probers and polymerase chain reaction methods are also being developed for rapid identification.
  • Detailed procedures of laboratory methods can be found in microbiology manuals.2
  • Antimicrobial susceptibility testing of AGNB has become less predictable because their resistance to several antimicrobials has increased.21 Screening of AGNB isolates for beta-lactamase activity may be helpful.13,22 However, occasional strains may resist beta-lactam antibiotics through other mechanisms.
  • Routine susceptibility testing is time-consuming and often unnecessary. However, testing the susceptibility of isolates recovered from sterile body sites and/or those that are clinically important (ie, blood cultures, bone, CNS, serious infections) and have variable susceptibilities, especially those isolated in pure culture from properly collected specimens, is important.3
    • Antibiotics that should be tested include penicillin, a broad-spectrum penicillin, a penicillin plus a beta-lactamase inhibitor, clindamycin, chloramphenicol, a second-generation cephalosporin (eg, cefoxitin), tigecycline, newer quinolones, metronidazole, and a carbapenem.
    • The recommended methods include agar microbroth and macrobroth dilution.
    • Newer methods include the E-test and the spiral gradient end point system.

Imaging Studies

  • Radiologic or imaging studies are helpful. Abscesses are a common complication of Bacteroides infections. The presence of gas in the infected site is highly suggestive of anaerobic infection.

More on Bacteroides Infection

Overview: Bacteroides Infection
Differential Diagnoses & Workup: Bacteroides Infection
Treatment & Medication: Bacteroides Infection
Follow-up: Bacteroides Infection
References
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References

  1. Brook I. Indigenous microbial flora of humans. In: Surgical Infectious Diseases. 3rd ed. Norwalk, Conn: Appleton & Lange; 1995:37.

  2. Jousime-Somers H, Summanen P, Citron DM. Belmont, Calif. Wadsworth-KTL Anaerobic Bacteriology Manual. 6th ed. Star Publishing; 2002.

  3. Wexler HM, Finegold SM. Current susceptibility patterns of anaerobic bacteria. Yonsei Med J. Dec 1998;39(6):495-501. [Medline].

  4. Brook I. Enhancement of growth of aerobic and facultative bacteria in mixed infections with Bacteroides species. Infect Immun. Dec 1985;50(3):929-31. [Medline].

  5. Durmaz B, Dalgalar M, Durmaz R. Prevalence of enterotoxigenic Bacteroides fragilis in patients with diarrhea: a controlled study. Anaerobe. Dec 2005;11(6):318-21. [Medline].

  6. Brook I. Treatment of anaerobic infection. Expert Rev Anti Infect Ther. Dec 2007;5(6):991-1006. [Medline].

  7. Finegold SM. Anaerobic Bacteria in Human Disease. Orlando, Fla: Academic Press; 1977.

  8. Brook I. Anaerobic bacterial bacteremia: 12-year experience in two military hospitals. J Infect Dis. Dec 1989;160(6):1071-5. [Medline].

  9. Brook I. Prevalence of beta-lactamase-producing bacteria in chronic suppurative otitis media. Am J Dis Child. Mar 1985;139(3):280-3. [Medline].

  10. Nord CE. The role of anaerobic bacteria in recurrent episodes of sinusitis and tonsillitis. Clin Infect Dis. Jun 1995;20(6):1512-24. [Medline].

  11. Brook I. The role of anaerobic bacteria in upper respiratory tract and other head and neck infections. Curr Infect Dis Rep. May 2007;9(3):208-17. [Medline].

  12. Brook I, Thompson DH, Frazier EH. Microbiology and management of chronic maxillary sinusitis. Arch Otolaryngol Head Neck Surg. Dec 1994;120(12):1317-20. [Medline].

  13. Brook I. The role of beta-lactamase-producing bacteria in the persistence of streptococcal tonsillar infection. Rev Infect Dis. Sep-Oct 1984;6(5):601-7. [Medline].

  14. Bartlett JG. Anaerobic bacterial infections of the lung and pleural space. Clin Infect Dis. Jun 1993;16 Suppl 4:S248-55. [Medline].

  15. Bohnen JM. Antibiotic therapy for abdominal infection. World J Surg. Feb 1998;22(2):152-7. [Medline].

  16. Goldstein EJ. Current concepts on animal bites: bacteriology and therapy. Curr Clin Top Infect Dis. 1999;19:99-111. [Medline].

  17. Brook I, Frazier EH. Clinical and microbiological features of necrotizing fasciitis. J Clin Microbiol. Sep 1995;33(9):2382-7. [Medline].

  18. Lewis RP, Sutter VL, Finegold SM. Bone infections involving anaerobic bacteria. Medicine (Baltimore). Jul 1978;57(4):279-305. [Medline].

  19. Dorsher CW, Rosenblatt JE, Wilson WR, Ilstrup DM. Anaerobic bacteremia: decreasing rate over a 15-year period. Rev Infect Dis. Jul-Aug 1991;13(4):633-6. [Medline].

  20. Lassmann B, Gustafson DR, Wood CM, Rosenblatt JE. Reemergence of anaerobic bacteremia. Clin Infect Dis. Apr 1 2007;44(7):895-900. [Medline].

  21. Snydman DR, Jacobus NV, McDermott LA, Ruthazer R, Golan Y, Goldstein EJ, et al. National survey on the susceptibility of Bacteroides fragilis group: report and analysis of trends in the United States from 1997 to 2004. Antimicrob Agents Chemother. May 2007;51(5):1649-55. [Medline].

  22. Nakano V, Padilla G, do Valle Marques M, Avila-Campos MJ. Plasmid-related beta-lactamase production in Bacteroides fragilis strains. Res Microbiol. Dec 2004;155(10):843-6. [Medline].

  23. Brook I. Treatment of anaerobic infection. Expert Rev Anti Infect Ther. Dec 2007;5(6):991-1006. [Medline].

  24. Brook I. Anaerobic Infections. Diagnosis and Management. In: Informa Healthcare USA, Inc. 4th Ed. New York, NY: 2007.

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Further Reading

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Keywords

anaerobic gram-negative bacilli, AGNB, Bacteroides fragilis, B fragilis, Prevotella species, Porphyromonas species, Bacteroides distasonis, B distasonis, Bacteroides ovatus, B ovatus, Bacteroides thetaiotaomicron, B thetaiotaomicron, Bacteroides vulgatus, B vulgatus, Prevotella melaninogenica, P melaninogenica, Prevotella intermedia, P intermedia, Porphyromonas asaccharolytica, P asaccharolytica, Prevotella oralis, P oralis, Prevotella oris, P oris, Prevotella bivia, P bivia, Bacteroides bivia, B bivia, Prevotella disiens, P disiens, Bacteroides disiens, Bacteroides melaninogenicus group, B melaninogenicus group, perirectal abscess, decubitus ulcer, bedsore, bed sore, pressure sore, intra-abdominal abscess, intraabdominal abscess, aspiration pneumonia, lung abscess, chronic otitis media, chronic sinusitis, oral cavity abscess, abscesses around the oral cavity, human bites, paronychia, brain abscesses, osteomyelitis, Bacteroidaceae

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Contributor Information and Disclosures

Author

Itzhak Brook, MD, MSc, Professor, Department of Pediatrics, Georgetown University School of Medicine
Itzhak Brook, MD, MSc is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians-American Society of Internal Medicine, American Federation for Clinical Research, American Medical Association, American Society for Microbiology, Armed Forces Infectious Diseases Society, Association of Military Surgeons of the US, Infectious Diseases Society of America, International Immunocompromised Host Society, International Society for Infectious Diseases, Medical Society of the District of Columbia, New York Academy of Sciences, Pediatric Infectious Diseases Society, Society for Ear, Nose and Throat Advances in Children, Society for Experimental Biology and Medicine, Society for Pediatric Research, Southern Medical Association, and Surgical Infection Society
Disclosure: Nothing to disclose.

Medical Editor

Jeffrey D Band, MD, Clinical Professor of Medicine, Wayne State University School of Medicine; Director, Division of Infectious Diseases and International Medicine, William Beaumont Hospital Corporation
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Ronald A Greenfield, MD, Professor, Department of Internal Medicine, Section of Infectious Diseases, University of Oklahoma College of Medicine
Ronald A Greenfield, MD is a member of the following medical societies: American College of Physicians, American Federation for Medical Research, American Society for Microbiology, Central Society for Clinical Research, Infectious Diseases Society of America, Medical Mycology Society of the Americas, Phi Beta Kappa, Southern Society for Clinical Investigation, and Southwestern Association of Clinical Microbiology
Disclosure: Pfizer Honoraria Speaking and teaching; Gilead Honoraria Speaking and teaching; Ortho McNeil Honoraria Speaking and teaching; Wyeth Honoraria Speaking and teaching; Abbott Honoraria Speaking and teaching; Astellas Honoraria Speaking and teaching; Cubist  Speaking and teaching

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

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.

 
 
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