Bacteriology of Wound - Clinical Utility of Gram Stain Microscopy and the Correlation with Culture
Journal
Macedonian Journal of Medical Sciences
Date Issued
2012-03
Author(s)
Igor Kaftandziev
Abstract
Aim: To determine the most common bacteria isolated from wound specimens and to compare those
culture results to Gram stain slides.
Material and methods: A total of 1970 specimens from 1788 patients, treated in the University Clinics
in Skopje during a one year period were examined by standard microbiology techniques (inoculation
onto standard agar media and direct Gram-stained smears). Automatized Vitek system was used for
identification of all anaerobes.
Results: Out of a total of 1970 specimens, 1094 (55.5 %) were positive by culture. A total of 1462 strains
were isolated: 753 Gram positive (Gram+), 661 Gram negative (Gram-) and 48 anaerobic bacteria. The
number of specimens yielding one, two or more different strains was 788, 244 and 62, respectively. Gram
+ bacteria, in 44.7 % of positive samples were a single isolate. The most commonly isolated potential
pathogen was Staphylococcus. In 23.7% samples, Gram negative bacteria were a single isolate (E. coli
was the most common isolate). 1094 specimens were positive by culture, 419 (38.3%) were positive by
both culture and Gram stain and 675 (61.7%) were negative by Gram stain (leukocytes were present in
276 specimens). 876 specimens were negative by culture, 789 (90%) were negative by both culture and
Gram stain (leukocytes were present in 271 specimen) and 87 (9.9%) were positive only by Gram stain.
Conclusion: Our study demonstrated only a 38.3 % of microbiological correlation between Gram stain
and culture. This data makes the clinical utility of Gram stain for the microbiological analysis of wounds
questionable.
culture results to Gram stain slides.
Material and methods: A total of 1970 specimens from 1788 patients, treated in the University Clinics
in Skopje during a one year period were examined by standard microbiology techniques (inoculation
onto standard agar media and direct Gram-stained smears). Automatized Vitek system was used for
identification of all anaerobes.
Results: Out of a total of 1970 specimens, 1094 (55.5 %) were positive by culture. A total of 1462 strains
were isolated: 753 Gram positive (Gram+), 661 Gram negative (Gram-) and 48 anaerobic bacteria. The
number of specimens yielding one, two or more different strains was 788, 244 and 62, respectively. Gram
+ bacteria, in 44.7 % of positive samples were a single isolate. The most commonly isolated potential
pathogen was Staphylococcus. In 23.7% samples, Gram negative bacteria were a single isolate (E. coli
was the most common isolate). 1094 specimens were positive by culture, 419 (38.3%) were positive by
both culture and Gram stain and 675 (61.7%) were negative by Gram stain (leukocytes were present in
276 specimens). 876 specimens were negative by culture, 789 (90%) were negative by both culture and
Gram stain (leukocytes were present in 271 specimen) and 87 (9.9%) were positive only by Gram stain.
Conclusion: Our study demonstrated only a 38.3 % of microbiological correlation between Gram stain
and culture. This data makes the clinical utility of Gram stain for the microbiological analysis of wounds
questionable.
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