In 70 strains of the genus Enterococcus belonging to 16 species and isolated from clinical material, animals and the environment, a hydroxamic class of siderophores was detected with the aid of chemical and biological tests. A correlation between siderophore activity and species affiliation was found: E. faecalis strains showed the highest siderophore activity. A correlation between siderophore activity and pathogenicity could not be confirmed.
The effect of Malassezia furfur on clot formation by human plasma was examined. The clotting time in the presence of M. furfur or Candida albicans was measured. M. furfur shortened the clotting time of calcium-induced clots by human plasma in a concentration-dependent manner. However, the protein content of the clots formed were not significantly different between the M. furfur-treated and the control group. The clotting time of clots triggered by thrombin or by placing plasma in glass tubes, which artificially activate the blood coagulation systems, were not affected by treatment with M. furfur. Moreover, acetone-treated M. furfur also shortens the calcium-induced clot formation time, while treatment with zymolyase, which causes decomposition of beta-glucan, did not shorten it. These results suggest that M. furfur activates the blood coagulation systems, and the beta-glucan portion of M. furfur plays a key role in shortening calcium-induced clot formation time.
Resistance to macrolides, lincosamides and streptogramin B (MLS) which is expressed either constitutively or inducibly, is mediated by erm genes (erm A, erm B, and erm C in staphylococci). The transposon TN 554, harbouring the erm A gene also encodes spectinomycin resistance. In Turkey, data related to MLS resistance phenotypes of staphylococci are not available. In this study, we screened 500 consecutive clinical isolates of staphylococci isolated in Hacettepe University Hospital, for MLS and spectinomycin resistance by the standard disk diffusion method. All MLS-resistant isolates were further tested for spectinomycin susceptibility by the agar screening method. Of 500 staphylococcal isolates, 368 (73.6%) were susceptible and 132 (26.4%) were resistant to MLS antibiotics. Ninety-one (18.2%) of the resistant isolates exhibited a constitutive resistance pattern, whereas 40 were inducibly resistant. MS (resistance to macrolides and lincosamides only) resistance was detected in only one isolate (0.2%). Of 40 inducibly resistant isolates, 21 were found to be resistant to spectinomycin by both the disk diffusion and agar screening tests, probably indicating a presence of the erm A gene. These results suggest that MLS resistance has been considerably high among clinical isolates of staphylococci in our hospital. On the whole, constitutive resistance was the pattern most frequently encountered. In contrast, MS resistance was very rare. Further epidemiological and molecular investigations are required for clarification of the data presented.
