Evidence Corner

  • Thu, 9/4/08 - 11:52am
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Author(s): 
Laura Bolton, PhD, FAPWCA


Dear Readers:

Managing wound infection requires quick, accurate action. After a clinician diagnoses signs of infection in a wound,1 invading microorganisms are sampled, cultured and identified along with antibiotic(s) to which they are sensitive. Then an appropriate antibiotic is prescribed and administered to quell the infection. Research has identified valid, reliable diagnostic clinical signs and symptoms of infection in chronic wounds despite ambiguity of some of these signals.2 Techniques for sampling invading microorganisms are controversial. For example, quantitative biopsies with > 1 x 105 or > 1 x 106 organisms per gram of tissue, often regarded as the “gold standard” sampling technique, have limited specificity, frequently over-predicting infections.3,4 This can result in unnecessary antibiotic use, which has been associated with delayed chronic wound healing5 and may foster development of resistant organisms. Quantitative biopsies also have low sensitivity, missing invasive organisms in 25% of burn biopsies,6 and low reliability, varying in bioburden by more than 2- log10 colony forming units (CFU) in 27% of paired isolates.6 Quantitative swab samples may be a viable alternative.1,7 Recent research is deriving an operational definition of a valid, reliable, quantitative microbial sampling technique capable of selectively identifying invading microorganisms in chronic wounds clinically diagnosed with an infection.8 Research described in this edition of Evidence Corner explores this operational definition.

Laura Bolton, PhD, FAPWCA

Adjunct Associate Professor
Department of Surgery, UMDNJ
WOUNDS Editorial Advisory Board Member and Department Editor
 

 

 

 

 

 

Diagnostic Validity of Quantitative Microbial Swab Techniques

Reference: Gardner SE, Frantz RA, Saltzman CL, Hillis SL, Park H, Scherubel M. Diagnostic validity of three swab techniques for identifying chronic wound infection. Wound Repair Regen. 2006;14(5):548–557.

Rationale: Cultures harvested from wounds using quantitative swab techniques are commonly used to evaluate the bioburden of potentially infected wounds. However, information from these swabs is often unclear owing to wide or unreported variations in harvesting and culturing techniques.

Objective: Compare the diagnostic validity of 3 standardized quantitative swab techniques in identifying chronic wound infection and explore the association of these bioburden measures with risk factors for wound infection.

References: 

1. Thomson PD, Smith DJ. What is infection? Am J Surg. 1994;167(1A Suppl):7S–11S.

2. Gardner SE, Frantz RA,Doebbeling BN.The validity of the clinical signs and symptoms used to identify localized chronic wound infection. Wound Repair Regen. 2001;9(3):178–186.

3. Robson MC, Heggers JP. Bacterial quantification of open wounds. Mil Med. 1969;134(1):19–24.

4. Robson MC, Duke WF, Krizek TJ. Rapid bacterial screening in the treatment of civilian wounds. J Surg Res. 1973;14(5):426–430.

5. Ennis WJ, Meneses P. Clinical evaluation: outcomes, benchmarking, introspection and quality improvement. Ostomy Wound Manage. 1996;42(10A Suppl):40S–47S.

6. Woolfrey BF, Fox JM, Quall CO. An evaluation of burn wound quantitative microbiology. I. Quantitative eschar cultures. Am J Clin Pathol. 1981;75(4):532–537.

7. Levine NS, Lindberg RB, Mason AD, Pruitt BA.The quantitative swab culture and smear:a quick,simple method for determining the number of viable aerobic bacteria on open wounds. J Trauma. 1976;16(2):89–94.

8. Gardner SE, Frantz R, Hillis, SL, Park H, Scherubel M. Diagnostic validity of semiquantitative swab cultures. WOUNDS. 2007;19(2):31–38.

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