The lack of clear recommendations on the implementation of microbiological analysis of wounds swabs and the interpretation of its results has led to the relevance of this study, which is aimed at comparing the data of microbiological cultures of wound swabs on solid media and enrichment broth (Tryptone Soya Broth).
AIM
To analyze the results of a microbiological study of samples of wound swabs from patients.
MATERIAL AND METHODS
Inoculation data of 405 wound swabs from patients with acute wounds (AW), n=176 and chronic wounds (CW), n=229 were used. Inoculation was carried out by a semi-quantitative sector method, supplemented by cultivation in an enrichment broth (Tryptone Soya Broth). The description of the microbiological structure of wounds included all microorganisms in any titer, including those from the enrichment broth. To compare the inoculation result with the clinical state of the wounds, an assessment of the infectious process according to «NERDS&STONEES» was used.
RESULTS
From the primary inoculation, microorganisms were more often isolated from CW (139 samples, 60.7%, 209 isolates), than from AW (76 samples, 43.2%, 106 isolates), χ2=12.26; p=0.005. After additional cultivation, the number of positive inoculation results increased to 76.1% (n=134) for AW, to 85.2% (n=195) for CW. Among the total number of microorganisms AW (n=193) and CW (n=314), isolates from the enrichment broth accounted for 47.2% and 39.0% in monocultures; 43.2% and 30.8% in associations. In an amount >105 CFU/ml, 30.3% of isolates (in monocultures) and 37.5% of isolates (in associations) were found from AW, 40% and 56.6%, respectively, in CW. In a titer of ≤105 CFU/ml, isolates were found in 22.5% and 19.2% in AW; 21.0% and 12.6% of cases in CW. Critical colonization was established in 74 (38%) patients with CW and a positive culture result, in 10 patients (5.3%) — deep infection; 56.7% (n=111) CW were considered colonized. Microorganisms from the enrichment broth with the same frequency were found in colonized and critically colonized CW — 25.2% (n=28), 29.7% (n=22). In 6 patients (60%) with signs of deep infection, microorganisms from the enrichment broth supplemented the microbiota of the primary inoculation. Granulating AWs also showed signs of colonization and critical colonization (n=36, 56.2% and n=28, 43.8%) upon positive inoculation from enrichment broth.
CONCLUSION
Additional cultivation expanded the qualitative characteristics of the detected microbiota, which increased the information content of the microbiological study of wound swabs. The presence of clinical signs of an infection presupposes accounting for microorganisms obtained only from enrichment broth, given the high frequency of their detection in colonized and critically colonized CW, granulating AW.
