Susceptibility of Pediococcus isolates to antimicrobial compounds in relation to hop-resistance and beer-spoilage.
BACKGROUND
Though important in the context of food microbiology and as potential pathogens in immuno-compromised humans, bacterial isolates belonging to the genus Pediococcus are best known for their association with contamination of ethanol fermentation processes (beer, wine, or fuel ethanol). Use of antimicrobial compounds (e.g., hop-compounds, Penicillin) by some industries to combat Pediococcus contaminants is long-standing, yet knowledge about the resistance of pediococci to antimicrobial agents is minimal. Here we examined Pediococcus isolates to determine whether antibiotic resistance is associated with resistance to hops, presence of genes known to correlate with beer spoilage, or with ability to grow in beer.


RESULTS
Lactic acid bacteria susceptibility test broth medium (LSM) used in combination with commercially available GPN3F antimicrobial susceptibility plates was an effective method for assessing antimicrobial susceptibility of Pediococcus isolates. We report the finding of Vancomycin-susceptible Pediococcus isolates from four species. Interestingly, we found that hop-resistant, beer-spoilage, and beer-spoilage gene-harbouring isolates had a tendency to be more susceptible, rather than more resistant, to antimicrobial compounds.


CONCLUSIONS
Our findings indicate that the mechanisms involved in conferring hop-resistance or ability to spoil beer by Pediococcus isolates are not associated with resistance to antibiotics commonly used for treatment of human infections. Also, Vancomycin-resistance was found to be isolate-specific and not intrinsic to the genus as previously believed.
Haakensen
Monique
M
Department of Pathology and Laboratory Medicine, Room 2841 Royal University Hospital, 103 Hospital Drive, University of Saskatchewan, Saskatoon, SK S7N 0W8, Canada. m.haakensen@usask.ca
Vickers
David M
DM
Ziola
Barry
B
D000890:Anti-Infective Agents / Q000494:pharmacology*; D001515:Beer / Q000382:microbiology*; D005506:Food Contamination; D005516:Food Microbiology; D027582:Humulus / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D010376:Pediococcus / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D013045:Species Specificity; D014640:Vancomycin / Q000494:pharmacology
D000890:Anti-Infective Agents; D014640:Vancomycin