TABLE 1.
Listeriophage susceptibility and glutamate-dependent acid resistance phenotypes of serotype group 4b(d,e) isolatesa
| Strain (isolation date) | Pulse type | Phage susceptibility (PFU/ml) | Glutamate-dependent acid resistance (% survival) |
|---|---|---|---|
| ATCC 13932 | ND | 3.1 × 107 ± 0.8 × 107 | 7.6 ± 0.91 |
| ATCC 19115 | ND | 4.4 × 107 ± 0.8 × 107 | 4.4 ± 0.84 |
| FL9 (6 March 2003) | P16 | R | 7.75 ± 2.6 |
| FL24 (12 June 2003) | P14 | 5.2 × 107 ± 0.6 × 107 | 0.145 ± 0.02 |
| FL25 (18 June 2003) | P15 | R | 2.5 ± 0.26 |
| FL26 (18 June 2003) | P15 | R | 2.7 ± 0.33 |
| FL27 (18 June 2003) | P15 | R | 2.45 ± 1.2 |
| FL59 (14 October 2003) | P17 | R | 0.33 ± 0.11 |
a
ND, not determined. Tests to determine the susceptibility to the listeriophage cocktail and acid shock assays were performed three to five times, and the results are expressed as means ± standard deviations. R, resistant to the listeriophage cocktail (101 to 0 PFU/ml). For the glutamate-dependent acid resistance system the percent survival was determined after acid shock in EG medium containing 1.5 mM glutamate (pH 2.5) for 1 h.