High prevalence of multidrug-tolerant bacteria and associated antimicrobial resistance genes isolated from ornamental fish and their carriage water.
BACKGROUND
Antimicrobials are used to directly control bacterial infections in pet (ornamental) fish and are routinely added to the water these fish are shipped in to suppress the growth of potential pathogens during transport.


RESULTS
To assess the potential effects of this sustained selection pressure, 127 Aeromonas spp. isolated from warm and cold water ornamental fish species were screened for tolerance to 34 antimicrobials. Representative isolates were also examined for the presence of 54 resistance genes by a combination of miniaturized microarray and conventional PCR. Forty-seven of 94 Aeromonas spp. isolates recovered from tropical ornamental fish and their carriage water were tolerant to > or =15 antibiotics, representing seven or more different classes of antimicrobial. The quinolone and fluoroquinolone resistance gene, qnrS2, was detected at high frequency (37% tested recent isolates were positive by PCR). Class 1 integrons, IncA/C broad host range plasmids and a range of other antibiotic resistance genes, including floR, bla(TEM-1), tet(A), tet(D), tet(E), qacE2, sul1, and a number of different dihydrofolate reductase and aminoglycoside transferase coding genes were also detected in carriage water samples and bacterial isolates.


CONCLUSIONS
These data suggest that ornamental fish and their carriage water act as a reservoir for both multi-resistant bacteria and resistance genes.
Verner-Jeffreys
David W
DW
Centre for Environment, Fisheries and Aquaculture Sciences, Weymouth Laboratory, Weymouth, Dorset, UK. david.verner-jeffreys@cefas.co.uk
Welch
Timothy J
TJ
Schwarz
Tamar
T
Pond
Michelle J
MJ
Woodward
Martin J
MJ
Haig
Sarah J
SJ
Rimmer
Georgina S E
GS
Roberts
Edward
E
Morrison
Victoria
V
Baker-Austin
Craig
C
D000333:Aeromonas / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D003001:Cloning, Molecular; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects* / Q000235:genetics*; D005399:Fishes / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial / Q000235:genetics*; D032023:Integrons / Q000235:genetics; D008826:Microbial Sensitivity Tests; D016254:Mutagenesis, Insertional / Q000187:drug effects / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D013696:Temperature; D014871:Water Microbiology
D000890:Anti-Infective Agents