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PCR detection of potentially pathogenic aeromonads in raw and cold‐smoked freshwater fish
Author(s) -
GonzálezRodríguez M.N.,
Santos J.A.,
Otero A.,
GarcíaLópez M.L.
Publication year - 2002
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.2002.01739.x
Subject(s) - biology , microbiology and biotechnology , fish <actinopterygii> , hemolysin , dna extraction , enterotoxin , polymerase chain reaction , veterinary medicine , food science , virulence , gene , fishery , escherichia coli , genetics , medicine
Aims: Development of a PCR assay for detection of aeromonads carrying the hly A and/or aer A genes in fish.
Methods and Results: The protocol involves an overnight selective enrichment step in tryptic soy broth yeast extract containing 10 µg ml ‐1 of ampicillin followed by extraction of DNA and PCR amplification of two haemolysin genes that contribute to the virulence of Aer. hydrophila . This procedure can detect initial populations of 1–10 cfu g −1 within 24 h in artificially contaminated samples. In naturally contaminated fish, both genes were detected in 13 out of 14 fresh fish lots (aeromonads levels between < 1 and 5·42 log cfu g −1 ) and in 4 out of 16 lots of vacuum‐packed cold‐smoked fish (aeromonads levels between < 1 and 3·37 log cfu g −1 ). Before enrichment, dominant species were Aer. hydrophila HG1 ( aer A + hly A + ), Aer . bestiarum HG2 ( aer A + hly A + ) and Aer. caviae HG4 ( aer A – hly A – ). After enrichment, Aer. hydrophila HG1 ( aer A + hly A + ) was dominant.
Conclusions: Fresh fish and even smoked fish carry hly A + and/or aer A + aeromonads that can be detected by PCR within 24 h.
Significance and Impact of the Study: The PCR assay described offers considerable potential as a rapid method with specificity, sensitivity and simplicity.