Antibiotic resistance among Listeria, including Listeria monocytogenes, in retail foods.
OBJECTIVE
In the past eight to 10 years, reports of antibiotic resistance in food-borne isolates in many countries have increased, and this work examined the susceptibility of 1001 food isolates of Listeria species.


RESULTS
Susceptibility/resistance to eight antibiotics was determined using the Bauer-Kirby disc diffusion assay, and 10.9% of the isolates examined displayed resistance to one or more antibiotics. Resistance to one or more antibiotics was exhibited in 0.6% of Listeria monocytogenes isolates compared with 19.5% of Listeria innocua isolates. Resistance was not observed in Listeria seeligeri or Listeria welshimeri. Resistance to tetracycline (6.7%) and penicillin (3.7%) was the most frequently observed, and while resistance to one antibiotic was most common (9.1%), isolates resistant to two or more antibiotics (1.8%) were also observed.


CONCLUSIONS
While resistance to the antibiotics most commonly used to treat human listeriosis was not observed in L. monocytogenes, the presence of such resistance in other Listeria species raises the possibility of future acquisition of resistance by L. monocytogenes.


CONCLUSIONS
The higher level of resistance in L. innocua compared with L. monocytogenes suggests that a species-related ability to acquire resistance to antibiotics exists.
Walsh
D
D
The National Food Centre, Teagasc, Dunsinea, Castleknock, Dublin 15, Ireland. d.walsh@nfc.teagasc.ie
Duffy
G
G
Sheridan
J J
JJ
Blair
I S
IS
McDowell
D A
DA
D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D005506:Food Contamination; D005516:Food Microbiology; D008089:Listeria monocytogenes / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D010400:Penicillin G / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D000667:Ampicillin; D013752:Tetracycline; D010400:Penicillin G