Drug Resistance and Broad Geographical Distribution of Identical R Plasmids of Pasteurella piscicida Isolated from Cultured Yellowtail in Japan

Abstract

An MIC test of 12 chemotherapeutic agents performed on 175 strains of Pasteurella piscicida collected from cultured yellowtail (Seriola quinqueradiata) in different areas of Japan from 1989 to 1991 revealed 152 strains (87%) with resistance to combinations of ampicillin (AP), chloramphenicol (CP), kanamycin (KM), nalidixic acid (NA), sulfamonomethoxine (SA), tetracycline (TC), and/or trimethoprim (TMP). The remaining 23 strains were sensitive to all the drugs tested: AP, cefazolin, CP, florfenicol (FF), furazolidone, KM, NA, novobiocin, SA, streptomycin, TC, and TMP. FF showed the most effective antibacterial activity against P. piscicida with MICs ranging from 0.004 to 0.6 μg/ml. One hundred and forty‐nine of the 152 resistant strains carried transferable R plasmids encoding one of the Cp Km Sa Tc, Km Sa Tc, Km Sa, and Sa resistance. The most common resistance marker of transferable R plasmids identified in P. piscicida was Km Sa Tc. R plasmids encoding three different resistant markers were very similar on the basis of their digestion patterns with restriction endonucleases. There was homology among the DNAs of nine transferable R plasmids selected. Our findings suggest that multiple drug resistant strains of P. piscicida carrying transferable R plasmids with the same DNA structure are common in yellowtail farms and that the R plasmid has been retained within the P. piscicida population without change in their DNA structure according to geography and year.

Sequence Analysis of the Florfenicol Resistance Gene Encoded in the Transferable R‐Plasmid of a Fish Pathogen, Pasteurella piscicida

“…However, the effectiveness of chemotherapy has been hampered by an increase of multiple drug resistance in P piscicida. The existence of transferable R plasmids and transposons that confer drug resistance account for the emergence of multiple drug-resistant strains of P. piscicida (1,9).…”

“…Florfenicol (FF), a fluorinated analog of thiamphenicol (TP) (11,14), has been evaluated as an effective therapeutic agent (5,9,16), and has been used to treat pseudotuberculosis in yellowtail farms since 1990. However, we reported that FF-resistant strains of P piscicida appeared suddenly in 1992 (10).…”

Cloning and Nucleotide Sequence Analysis of the Ampicillin Resistance Gene on a Conjugative R Plasmid from the Fish PathogenPhotobacterium damselaesubsp.piscicida

“…Escherichia coli JM83 cells harboring a recombinant plasmid (pHSG398, which has a fragment of pPDP8517) had a highly elevated level of resistance to ampicillin (Ͼ100 g/mL) compared with that of the host strain (Ͻ3.1 g/mL), indicating that the cloned insert from the P. damselae plasmid contained an ampicillin resistance gene. Earlier studies had concluded that ampicillin resistance in P. damselae was chromosomal (Takashima et al 1985;Kim and Aoki 1993), but Takashima et al (1985) reported one case of ampicillin resistance being harbored by a plasmid. Our study is the first report of a ␤-lactamase gene isolated from P. damselae.…”

Aquaculture and Florfenicol Resistance inSalmonella entericaTyphimurium DT104

“…The strains of fl orfenicol-resistant P. piscicida were fi rst isolated in Japan in 1992 (5). However, a previous study (8) had demonstrated 100% susceptibility to fl orfenicol of P. piscicida strains isolated from 1989 through 1991. Because this study examined 175 P. piscicida strains isolated from fi sh farms distributed over a wide geographic area in Japan, the data it generated provide strong support for the conclusions that fl o-mediated fl orfenicol resistance in P. piscicida fi rst emerged in Japanese aquaculture in 1992 (5).…”