The 16.5-kbp plasmid pSCFS1 from Staphylococcus sciuri mediated combined resistance to chloramphenicol and florfenicol. The gene responsible for this resistance property, cfr, was cloned and sequenced. The amino acid sequence of the Cfr protein revealed no homology to known acetyltransferases or efflux proteins involved in chloramphenicol and/or florfenicol resistance or to other proteins whose functions are known.Staphylococcus sciuri is a common inhabitant of the physiological skin flora of most rodents, ungulates, carnivora, and marsupials. Although classified as rarely pathogenic (6), S. sciuri isolates have been obtained occasionally from cases of mastitis in goats (10) and bronchopneumonia in cattle (13). Antimicrobial resistance is common among S. sciuri isolates, and a number of plasmids carrying one or more resistance genes have been identified (11,13,14). Resistance to chloramphenicol (CM) in staphylococci has usually been associated with plasmid-borne cat genes (11, 13), whose gene products inactivate CM by diacetylation. CM acetyltransferases, however, are unable to inactivate florfenicol (FF), a fluorinated CM derivative which was licensed in Germany in 1995 as a therapeutic agent to control bacterial respiratory infections in cattle. Genes whose gene products mediate combined resistance to CM and FF by efflux of both drugs have been identified in gram-negative bacteria, such as Salmonella enterica serovar Typhimurium (2) and Photobacterium damselae subsp. piscicida, formerly known as Pasteurella piscicidae (5). In staphylococci and related organisms, FF resistance genes have not been described yet.An S. sciuri isolate obtained from the nasal swab of a calf suffering from an infection of the respiratory tract proved to be resistant to tetracycline, erythromycin, kanamycin, CM, and FF. Plasmid analysis revealed the presence of six plasmids in the size range between 1.5 and 16.5 kbp. Experiments involving transformation into protoplasts of Staphylococcus aureus RN4220 (12) and subsequent selection of the transformants on regeneration media containing 20 g of FF/ml (Essex, Munich, Germany) identified only the 16.5-kbp plasmid, designated pSCFS1, as the mediator of resistance to CM and FF. This plasmid also mediated resistance to erythromycin by an inducibly expressed ermC gene as confirmed by PCR analysis (7). Cloning experiments revealed that the ermC gene was located on a 2.5-kbp PstI fragment of pSCFS1 (data not shown). The original S. sciuri isolate and S. aureus RN4220:pSCFS1 showed FF MICs of 64 g/ml and CM MICs of 32 g/ml. Preincubation of these isolates in the presence of either 0.5 g of FF or 0.5 g of CM increased the FF MICs to 512 g/ml and the CM MICs to 64 g/ml, suggesting that pSCSF1-mediated resistance to FF and CM in both staphylococcal hosts is inducible by FF as well as CM. Plasmid pSCFS1 was mapped ( Fig. 1) and subjected to cloning experiments. Restriction fragments of pSCFS1 generated by the enzymes EcoRI and BclI-BamHI were cloned into pBluescript SKII ϩ . The recombinant plasmids ...

-Besides their role as commensals on the skin and mucosal surfaces, staphylococci may be involved in a wide variety of diseases in animals. Staphylococcal infections in animals are mainly treated with antimicrobial agents and as a consequence, staphylococci from animal sources have developed and/or acquired resistance to the respective antimicrobial agents. Resistance statistics obtained from national monitoring programmes on staphylococci from cattle and pigs, but also from surveillance studies on staphylococci involved in diseases in dogs are reported and reviewed with regard to their comparability. This review mainly focusses on the genetic basis of antimicrobial resistance in staphylococci of animal origin. Particular attention is paid to resistance to those antimicrobial agents which are most frequently used in veterinary medicine, but also to antimicrobial agents, such as chloramphenicol and mupirocin, which are used in specific cases for the control of staphylococcal infections in pets and companion animals. In addition, plasmids and transposons associated with the respective resistance properties and their ways of spreading between members of the same or different staphylococcal species, but also between staphylococci and other gram-positive bacteria, are described.antimicrobial resistance / Staphylococcus / animal origin / epidemiology / horizontal gene transfer Vet. Res. 32 (2001) 341

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We screened 183 different clinical anaerobic and aerobic bacteria isolated from humans and other animals for the presence of the ermF gene using a polymerase chain reaction (PCR) assay. The ermF gene was detected in 107 (58%) clinical isolates, including 42 (61%) of 69 gram-positive bacteria and 65 (57%) of 114 gram-negative bacteria. Twenty-five ATCC isolates were also tested; 20 (80%) carried the ermF gene. The gene products from the ermF PCR from four isolates were sequenced and showed 95-99% nucleotide homology with the ermF gene and 98-99% amino acid homology with the gene product. Eleven (58%) of the 19 gram-negative donors tested were able to transfer the ermF gene. All nine (100%) of the gram-positive donors tested transferred the ermF gene, using either Enterococcus faecalis or Haemophilus influenzae as the recipients.