Molecular analysis of florfenicol-resistant Pasteurella multocida isolates in Germany.
OBJECTIVE
Three florfenicol-resistant Pasteurella multocida isolates from Germany, two from swine and one from a calf, were investigated for the genetics and transferability of florfenicol resistance.


METHODS
The isolates were investigated for susceptibility to antimicrobial agents and plasmid content. Florfenicol resistance plasmids carrying the gene floR were identified by transformation and PCR. Plasmids were mapped, and a novel plasmid type was sequenced completely. PFGE served to determine the clonality of the isolates.


RESULTS
In one porcine and the bovine P. multocida isolate, florfenicol resistance was associated with the plasmid pCCK381 previously described in a bovine P. multocida isolate from the UK. The remaining porcine isolate harboured a new type of floR-carrying plasmid, the 10 226 bp plasmid pCCK1900. Complete sequence analysis identified an RSF1010-like plasmid backbone with the mobilization genes mobA, mobB and mobC, the plasmid replication genes repA, repB and repC, the sulphonamide resistance gene sul2 and the streptomycin resistance genes strA and strB. The floR gene area was integrated into a region downstream of strB, which exhibited homology to the floR flanking regions found in various bacteria. PFGE revealed that the floR-carrying P. multocida strains from Germany were unrelated and also different from the UK strain.


CONCLUSIONS
After the UK and France, floR-mediated florfenicol resistance has now also been identified in target bacteria from Germany. PFGE data and the analysis of plasmids strongly suggested that the spread of florfenicol resistance is due to the horizontal transfer of plasmids rather than the clonal dissemination of a resistant P. multocida isolate.
Kehrenberg
Corinna
C
Institute of Farm Animal Genetics, Friedrich-Loeffler-Institute, Neustadt-Mariensee, Germany.
Wallmann
Jürgen
J
Schwarz
Stefan
S
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D002874:Chromosome Mapping; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D005838:Genotype; D005858:Germany; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010326:Pasteurella Infections / Q000382:microbiology / Q000662:veterinary*; D016979:Pasteurella multocida / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*; D010957:Plasmids / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D013839:Thiamphenicol / Q000031:analogs & derivatives* / Q000494:pharmacology; D014170:Transformation, Genetic
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; C035534:florfenicol; D013839:Thiamphenicol