Plasmid-mediated florfenicol resistance in Mannheimia haemolytica isolated from cattle.
The aim of this study was to analyse a florfenicol-resistant Mannheimia haemolytica isolated from a calf to determine the genetic basis of its florfenicol-resistance. The antimicrobial susceptibility and plasmid content of the isolate were determined. A florfenicol resistant plasmid carrying the floR gene was identified by PCR and transformed into Escherichia coli JM109 and HB101 strains. The plasmid was then mapped and sequenced completely. The isolate was resistant to chloramphenicol, florfenicol, oxytetracycline, kanamycin, dihydrostreptomycin, nalidixic acid, ampicillin, and amoxicillin; it carried a floR plasmid of 7.7kb, designated pMH1405. The mobilisation and replication genes of pMH1405 showed extensive similarity to the 5.1-kb pDN1 plasmid from Dichelobacter nodosus and the 10.8-kb pCCK381 plasmid from Pasteurella multocida. An adjacent 2.4-kb segment was highly homologous to the TnfloR region of the E. coli BN10660 plasmid. A plasmid-mediated floR gene was responsible for florfenicol resistance in the bovine respiratory tract pathogen M. haemolytica. The pMH1405 plasmid is the smallest floR-carrying plasmid reported to date. To the best of our knowledge, this is the first report of a florfenicol-resistant gene in M. haemolytica.
Tohoku Research Station, Viral Disease and Epidemiology Research Division, National Institute of Animal Health, 31 Uminai, Shichinohe, Kamikita, Aomori 039-2586, Japan.
Ken
K
Katsuda
Mariko
M
Kohmoto
Osamu
O
Mikami
Yukino
Y
Tamamura
Ikuo
I
Uchida
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle; D002701:Chloramphenicol / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000235:genetics; D016978:Mannheimia haemolytica / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D012766:Pasteurellosis, Pneumonic / Q000382:microbiology; D010957:Plasmids / Q000235:genetics*; D013839:Thiamphenicol / Q000031:analogs & derivatives* / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D002701:Chloramphenicol; C035534:florfenicol; D013839:Thiamphenicol