TABLE 1.
PCR and Southern blot analyses of L. monocytogenes strainsa
| Strain | Origin | Serotype or subgroupb | Ribotypec | Rhamnose usaged | PCR amplification resulte
|
Size of band(s) (kb) by Southern hybridization with the following probe:
|
|||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 800 bp (inlA) | 453 bp (lmo0733) | 611 bp (lmo2821) | 481 bp (lmo2672) | 367 bp (lmo1134) | 471 bp (ORF2819) | lmo0733 | lmo2821 | lmo2672 | |||||
| RM2989 | Milk | 1/2a | ND | ND | + | + | + | + | + | − | 5.0 | 5.0 | 2.5 |
| RM3158 | Human | 1/2b | ND | ND | + | + | + | + | + | + | 6.0 | 5.0 | 2.5 |
| RM3367 | Environment | 1/2c | ND | ND | + | + | + | + | + | − | 5.0 | 5.0 | 2.5 |
| RM3162 | Human | 3a | ND | ND | + | + | + | + | + | − | 1.5 | 4.0, 1.5 | 2.5 |
| RM3836 | Beef frank | 3b | ND | ND | + | + | + | + | + | + | 6.0 | 5.0 | 2.5 |
| RM3027 | Human | 3c | ND | ND | + | + | + | + | + | − | 5.0 | 5.0 | 2.5 |
| HCC23 | Catfish | 4a | ND | ND | + | + | − | − | − | − | 1.5 | ||
| ATCC 19115 | Human | 4b | ND | ND | + | + | + | + | + | + | 6.0 | 5.0 | 2.5 |
| ATCC 19116 | Chicken | 4c | ND | ND | + | + | + | − | − | − | 3.0, 1.5 | 1.5 | |
| ATCC 19117 | Sheep | 4d | ND | ND | + | + | + | + | + | + | 6.0 | 5.0 | 2.5 |
| ATCC 19118 | Chicken | 4e | ND | ND | + | + | + | + | + | + | 5.0 | 5.0 | 2.5 |
| F2-458 | Human | IIIA | DUP-1061A | + | + | + | + | − | − | − | 1.5 | 1.5, 1.0 | |
| J1-031 | Human | IIIA | DUP-1059A | + | + | + | + | − | − | − | 3.0, 1.5 | 2.0 | |
| J1-168 | Human | IIIA | DUP-18606 | + | + | + | + | − | − | − | 3.0 | 4.0, 2.0 | |
| J2-071 | Animal | IIIA | DUP-1061A | + | + | + | + | − | − | − | 1.5 | 3.0 | |
| J2-074 | Animal | IIIA | DUP-10146 | + | + | + | + | − | − | − | 3.0 | 5.0 | |
| R2-128 | Food | IIIA | DUP-1061A | + | + | + | + | − | − | − | 1.5 | 1.5, 1.0 | |
| X1-002 | Food | IIIA | DUP-1059B | + | + | + | − | − | − | − | 1.5 | ||
| X1-011 | Food | IIIA | DUP-1036A | + | + | + | − | − | − | − | 5.0 | ||
| F2-086 | Human | IIIB | DUP-10142 | − | + | − | − | + | − | − | 5.0 | ||
| F2-407 | Human | IIIB | DUP-18036 | − | + | − | − | + | − | − | 5.0 | ||
| J1-158 | Animal | IIIB | DUP10142 | − | + | − | − | + | − | − | 5.0 | ||
| M2-030 | Unknown | IIIB | DUP10142 | − | + | − | − | + | − | − | 5.0 | ||
| R2-142 | Food | IIIB | DUP-18036 | − | + | − | − | + | − | + | 5.0 | ||
| W1-112 | Unknown | IIIB | DUP-1033A | − | + | − | − | + | − | + | 5.0 | ||
| F2-208 | Human | IIIC | DUP-10148 | − | + | + | + | + | − | − | 1.5 | 1.5, 1.0 | 5.0 |
| F2-270 | Human | IIIC | DUP-18007A | − | + | + | + | + | − | − | 1.5 | 1.5, 1.0 | 5.0 |
| F2-595 | Human | IIIC | DUP-18007A | − | + | + | + | + | − | − | 1.5 | 1.5, 1.0 | 5.0 |
| M1-003 | Animal | IIIC | DUP-10148 | − | + | + | + | + | − | − | 1.5 | 1.5, 1.0 | 5.0 |
| W1-110 | Unknown | IIIC | DUP-1055A | − | + | + | + | + | − | − | 3.0 | 1.5, 1.0 | 5.0 |
Amplified rRNA gene restriction analysis was performed on all 30 strains by PCR using primers derived from the E. coli 16S rRNA gene followed by digestion with restriction enzyme AluI. All 30 strains tested showed pattern 1, which indicates L. monocytogenes(18).
The serotype (serotypes 1/2a to 4e) was determined by agglutination and enzyme-linked immunosorbent assay (11), and the subgroup (subgroups IIIA, IIIB, and IIIC) was ascertained by phylogenetic examination of actA and sigB genes as well as phenotypic characterization (14).
The ribotype was based on the EcoRI ribotype pattern generated with the RiboPrinter (14). ND, not done.
The rhamnose usage was evaluated as described elsewhere (14). +, used rhamnose; −, did not use rhamnose; ND, not done.
The presence (+) or absence (−) of a band of the indicated size by PCR amplification with the specific primers shown.