Species | Catecholamine μM | a No antagonist | Chlorpromazine | Phentolamine | Phenoxybenzamine | Prazosin |
|---|
| |
NE
| | N/D | | | |
E. coli O157:H7 | b 0 | 4.62 | | 3.91 | 4.6 | 4.00 |
| | 5 | 6.77 | | 4.64 | 4.66 | 4.77 |
| | 50 | 8.03 | | 5.19 | 5.02 | 5.75 |
| | 100 | 8.40 | | 5.84 | 6.00 | 6.82 |
| | 200 | 8.42 | | 7.33 | 7.42 | 7.88 |
| | 500 | 8.41 | | 8.24 | 8.33 | 8.24 |
| |
Epi
| | N/D | | | |
| | 5 | 4.92 | | 4.00 | 3.83 | 4.08 |
| | 50 | 7.28 | | 5.19 | 4.32 | 5.72 |
| | 100 | 8.05 | | 5.76 | 5.75 | 6.82 |
| | 200 | 8.24 | | 7.25 | 7.95 | 7.85 |
| | 500 | 8.00 | | 8.05 | 8.08 | 8.09 |
| |
Dop
| | | N/D | N/D | N/D |
| | 5 | 5.82 | 4.68 | | | |
| | 50 | 8.03 | 5.90 | | | |
| | 100 | 8.36 | 6.53 | | | |
| | 200 | 8.13 | 6.83 | | | |
| | 300 | 8.06 | 7.60 | | | |
Y. enterocolitica
|
NE
| | N/D | | | |
| | 0 | 3.87 | | 3.83 | 3.83 | 3.82 |
| | 5 | 4.65 | | 4.00 | 4.32 | 4.47 |
| | 50 | 8.03 | | 5.75 | 5.71 | 5.74 |
| | 100 | 8.09 | | 6.78 | 5.82 | 6.56 |
| | 200 | 8.04 | | 7.00 | 7.54 | 7.94 |
| | 500 | 8.00 | | 8.02 | 8.05 | 8.00 |
| |
Dop
| | | N/D | N/D | N/D |
| | 5 | 5.66 | 4.62 | | | |
| | 50 | 7.47 | 5.19 | | | |
| | 100 | 8.11 | 6.12 | | | |
| | 200 | 8.02 | 6.50 | | | |
| | 300 | 7.78 | 7.95 | | | |
- E. coli O157:H7 and Y. enterocolitica were inoculated at approximately 102 CFU/ml into duplicate 1 mL aliquots of serum-SAPI containing either no additions (No antagonist, 0) or only the NE, Epi and Dop concentrations shown (No antagonist). To determine if increasing the catecholamine concentration overcame antagonists effects, the same concentrations of NE or Epi or Dop were incubated with 200 μM additions of the dopaminergic antagonist chlorpromazine, or the α-antagonists phentolamine, phenoxybenzamine and prazosin. Note that usage of Dop was limited to 300 μM because higher concentrations were inhibitory to Y. enterocolitica (See Figure 1). Cultures were incubated for either 18 hours (E. coli O157:H7) or 40 hours (Y. enterocolitica), and enumerated for growth (a, expressed as log-10 CFU/ml) as described in Materials and Methods. Growth levels of non-catecholamine supplemented cultures (0, b) are shown for comparison purposes. N/D – not determined. The results shown are representative data from two separate experiments; all data points showed variation of less than 3%. α-adrenergic antagonist-supplemented NE and Epi cultures showed statistically significant decreases in growth levels (P < 0.001) as compared with control (catecholamine-only supplemented) cultures. Similar results to those shown for E. coli O157:H7 were also obtained for S. enterica.
