Open AccessNatural Atypical Listeria innocua Strains with Listeria monocytogenes Pathogenicity Island 1 Genes
Author(s) -
Janelle M. Johnson,
Karen C. Jinneman,
Gerard N. Stelma,
Bennett G. Smith,
Dennis J. Lye,
James W. Messer,
Jodie Ulaszek,
L. Evsen,
Steven M. Gendel,
Reginald W. Bennett,
Bala Swaminathan,
J Pruckler,
A G Steigerwalt,
Sophia Kathariou,
Süleyman Yıldırım,
Dmitriy V. Volokhov,
Avraham Rasooly,
Vladimir Chizhikov,
Martin Wiedmann,
Esther D. Fortes,
Robert E. Duvall,
Anthony D. Hitchins
Publication year - 2004
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.70.7.4256-4266.2004
Subject(s) - listeria , biology , virulence , listeria monocytogenes , microbiology and biotechnology , pathogenicity island , gene , genetics , virology , bacteria
Identification of bona fide Listeria isolates into the six species of the genus normally requires only a few tests. Aberrant isolates do occur, but even then only one or two extra confirmatory tests are generally needed for identification to species level. We have discovered a hemolytic-positive, rhamnose and xylose fermentation-negative Listeria strain with surprising recalcitrance to identification to the species level due to contradictory results in standard confirmatory tests. The issue had to be resolved by using total DNA-DNA hybridization testing and then confirmed by further specific PCR-based tests including a Listeria microarray assay. The results show that this isolate is indeed a novel one. Its discovery provides the first fully documented instance of a hemolytic Listeria innocua strain. This species, by definition, is typically nonhemolytic. The L. innocua isolate contains all the members of the PrfA-regulated virulence gene cluster (Listeria pathogenicity island 1) of L. monocytogenes. It is avirulent in the mouse pathogenicity test. Avirulence is likely at least partly due to the absence of the L. monocytogenes-specific allele of iap, as well as the absence of inlA, inlB, inlC, and daaA. At least two of the virulence cluster genes, hly and plcA, which encode the L. monocytogenes hemolysin (listeriolysin O) and inositol-specific phospholipase C, respectively, are phenotypically expressed in this L. innocua strain. The detection by PCR assays of specific L. innocua genes (lin0198, lin0372, lin0419, lin0558, lin1068, lin1073, lin1074, lin2454, and lin2693) and noncoding intergenic regions (lin0454-lin0455 and nadA-lin2134) in the strain is consistent with its L. innocua DNA-DNA hybridization identity. Additional distinctly different hemolytic L. innocua strains were also studied.