Identification of Listeria monocytogenes from unpasteurized apple juice using rapid test kits.
A microbiological survey of 50 retail juices was conducted in the fall of 1996. These juices were analyzed for Listeria monocytogenes, Escherichia coli O157:H7, Salmonella, coliforms, fecal coliforms, and pH. Two unpasteurized juices were positive for L. monocytogenes: an apple juice and an apple raspberry blend with a pH of 3.78 and 3.75, respectively. Three L. monocytogenes isolates were characterized. The colonies were typical for Listeria sp. on Oxford and lithium chloride-phenylethanol-moxalactam agars and were beta-hemolytic on sheep blood agar. The isolates required 5 days of incubation at 35 degrees C to produce a positive rhamnose reaction in a phenol red carbohydrate broth. This slow rhamnose utilization resulted in these isolates not being identified using the Micro-ID test strip (Organon Technika). However, the isolates were positive for L. monocytogenes using the API Listeria strip (BioMerieux) and a multiplex polymerase chain reaction for detection of the hemolysis (hyla) and invasion-associated protein (iap) genes.
Sado
P N
PN
U. S. Food and Drug Administration, Bothell, Washington 98041, USA. psado@ora.fda.gov
Jinneman
K C
KC
Husby
G J
GJ
Sorg
S M
SM
Omiecinski
C J
CJ
D001431:Bacteriological Techniques; D001628:Beverages / Q000382:microbiology*; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D005506:Food Contamination; D005638:Fruit / Q000382:microbiology; D006461:Hemolysis / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods; D011933:Reagent Kits, Diagnostic; D013242:Sterilization
D003470:Culture Media; D004269:DNA, Bacterial; D011933:Reagent Kits, Diagnostic