Now it is not yet known exactly what happens before: tumor invasion and the associated
change in the microbiota, or, conversely, changes in the microbiota induce tumor invasion.
Aim: to investigate the contamination and colonization of microbes in skin melanoma.
Methods. In 23 primary melanoma patients the samples for microbiological exam were taken
from melanoma surfaces and from non-lesion skin before surgery. Microorganisms were cultured at
optimal temperatures on appropriate for each taxon elective or differential media and were
identified by bacterial analyzer. After wide local excision of melanoma the histological exam
determines Breslow thickness and Clark’s level of melanoma invasion; the Loeffler's methylene
blue staining was used to detect the colonies of microorganisms.
Results. From intact skin 62 bacterial cultures were isolated with density of colonization in
1.2×10 3 – 6.4×10 3 CFU/cm 2 . From ulcerated surface of melanoma 25 bacterial cultures were
identified. The concentration of microorganisms was significantly higher on melanoma ulcer. The
colonization density of S. aureus was the highest; its concentration was 5.8×10 7 comparing to
6.4×10 3 CFU/cm 2 on intact skin. Concentration of gram-negative rods was high also; e.g: E. coli and
P. putida were 6.2×10 6 and 1.8×10 5 CFU/cm 2 respectively. The Loeffler's staining of histological
specimens reveals the colonies of microorganisms at the bottom of melanoma ulcer. In case of
ulcerated melanoma with Clark level IV invasion the microbial colonies were identified in the
Conclusions. The spectrum of microorganisms on the surface of intact skin is twice as large
(62 vs. 25) as on surface of ulcerative melanoma, but the concentration of microorganisms is
significantly higher on ulcer tumor’s (10 5 –10 7 ) surface than intact skin (10 3 –10 4 ).
Microbiota on the surface of the chronic ulcer may increase local pathogenicity leading to
tissue degradation that may be essential for intradermal melanoma invasion.