Opportunistic coryneform organisms--residents of human skin.

Opportunistic infections are usually caused by endogenic flora originated from physiological flora. In this context we studied coryneform bacteria recovered from deeper layers of epidermis of the forehead (278 isolates) and the back (196 isolates) of healthy men. It was observed that coryneform bacteria are in dynamic equilibrium with coagulase-negative staphylococci and they amount 4,7% of resident aerobic flora. On the base of biological and metabolic features 49 different biotypes were indicated. Biotypes of lipophilic rods were the basic part of coryneform flora existing for long period. The most frequently isolated taxa were C. jeikeium (31%), CDC group G2 (23,4%), next in order CDC group G1 (11%) and C. afermentans ssp. lipophiluni (7%). These isolates were phenotypically differentiated. Nonlipophilic species did not play significant role in creating resident flora of the skin. The significance of coryneform bacteria in opportunistic infections is growing, especially in immunocompromissed patients. Isolated lipophilic taxa belong to these taxa coryneforms which are described in literature as the main etiologic factors of opportunistic infections.

Bacteria forming a resident flora of the skin as a potential source of opportunistic infections.

Along with progress of medicine, contribution that opportunistic bacteria make in nosocomial infections increases. Coagulase-negative staphylococci are these multiresistant strains which often cause this kind of infections. But more and more frequently other genera of bacteria are isolated. The main source of them is first and foremost the hospitalized patient's endogenous flora e.g. from their skin, because transmission of bacteria from this source is very effective. Analysis was concerned with bacteria that were recovered repeatedly from the skin of young, healthy men during period of five months. Composition of resident bacteria, after removing transients was evaluated. The number of microorganisms per 1 cm2 patients' skin was a constant value but different for each patient. Newly composed media enabled exact isolation and qualitative analysis of all groups of expected bacteria. Isolated microorganisms represented three main groups: sensitive to novobiocin staphylococci, microaerophilic rods from Propionibacterium genus and corynefonn bacteria. Aside from quantitative differences in total bacteria number, significant differences in contribution of aerobic and anaerobic flora living on patient skin were observed. A persistent although not predominant population occurring on the skin of all patients in similar number (average 2%), were coryneform bacteria. They mainly belonged to the Corynebacteriumn genus, and 84.7% of them were the lipophilic species. These bacteria deserve special attention because among such species isolated from nosocomial infections, multiple antibiotic resistance of unknown origin was described.