The occurrence and the further spread of high-level glycopeptide-resistant, vanA-positive Enterococcus faecium strains outside of hospitals have been investigated. We could isolate such bacteria directly from thawing liquids of commercially produced frozen poultry (chickens, turkeys; no further data on previous feeding with avoparcin were available). In 5 of 13 samples of raw minced meat of pigs originating from 13 different butcher's shops, glycopeptide-resistant E. faecium (VanA type) could be detected after overnight broth cultivation of these samples. No glycopeptide-resistant enterococci could be isolated from meat samples of chickens that were fed without avoparcin. VanA type E. faecium strains were also identified in 12 fecal samples recovered from 100 nonhospitalized humans in the rural area of Saxony-Anhalt federal county. These results suggest a possible role of the food chain in the spread of glycopeptide-resistant E. faecium. Molecular typing (macrorestriction and multilocus enzyme analysis) reveal a wide dissemination of the vanA gene among strains of different ecological origins.

The semisynthetic streptogramin combination quinupristin/dalfopristin (Synercid) is a promising alternative for treatment of infections due to multiply resistant gram-positive bacteria including vancomycin-resistant Enterococcus faecium. Resistance is mediated by acetyltransferases SatA (VatD) or SatG (VatE). Recent papers have indicated a possible link between the use of the streptogramin virginiamycin S/M as a feed additive in commercial animal husbandry and a selection of quinupristin/dalfopristin-resistant E. faecium (QDRE). We screened manure samples from two different turkey farms and from six different pig farms (using virginiamycin), samples from a sewage water treatment plant, 24 broiler carcasses, 10 pork samples, and 200 stool samples of nonhospitalized humans for QDRE. Our strain culture collection of hospital E. faecium isolates from the last 2 years was also reviewed for QDRE. All manure and sewage samples were positive for QDRE, as well as 11 from broiler carcasses (46%), 1 from pork (10%), and 28 from human stool specimens (14%). Thirty-six hospital isolates of E. faecium exhibited resistance to quinupristin/dalfopristin. In 141 QDRE of different origin satA (vatD) and satG (vatE) genes were detected (seven isolates from humans with an unknown resistance mechanism). Streptogramin resistance determinants were tansferable in filtermating experiments for 5 of 10 satA (vatD) and 9 of 22 satG (vatE) isolates. Different EcoRI patterns of satG (vatE) plasmids and corresponding hybridizations of the satG (vatE) gene indicated nonhomologous resistance plasmids in isolates of different origin. The results of this study indicate a common gene pool for streptogramin resistance in E. faecium of different ecological origin. A selection of QDRE using the streptogramin virginiamycin S/M as a feed additive and a spread of the resistance via the food chain to humans is probable.

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Storage of Salmonella enterica serovar Typhimurium strains in soil and water microcosms resulted in loss of culturability on standard plating media. Prior incubation in buffered peptone water supplemented with ferrioxamine E markedly extended the time that bacteria were recoverable by plating, except in the case of mutants deficient in ferrioxamine E uptake.

Summary: Before the introduction of gentamicin, trimethoprim, or streptothricins for therapeutic or ergotropic purposes in the GDR respective resistance plasmids could not be detected in enteric bacteria from sewage, surface water or clinical specimens, even if the selection was carried out on drug containing media. After a certain time of continuous drug application the rise of particular plasmids encoding gentamicin (IncM), trimethoprim (IncIB), or streptothricin resistance (IncW3) was observed much earlier in enteric bacteria from sewage, waste water and surface water than in bacteria from clinical sources. These observations werc further supported by surveying other plasmid species encoding gentamicin (IncOF, IncD, IncC), trimethoprim (IncK, IncZ, IncFII, IncN, IncWS), or streptothricin (IncI2, IncX, IncFII, IncI1, IncS, IncN) resistance. They appeared also a t first in bacteria from sewage and surface water, then, some time later, in bacteria from clinical sources. Therefore, one must admit a key position of sewage and surface water for the surveillance of infectious drug resistance.