TABLE 1.
Counts of presumptive VRE and occurrence of vanA-positive isolates in different environmental samples
| Sample type | Source | Total no. (CFU/ml or g [%]) of presumptive VREa |
vanA PCR
|
|
|---|---|---|---|---|
| No. of tested isolates | No. (%) of positive isolates | |||
| Vancomycin sludge | Pharmaceutical plant | 109 (>100) | 16 | 15 (94) |
| Vancomycin effluent | Pharmaceutical plant | 103 (<1-100) | 11 | 9 (82) |
| Polymyxin effluent | Pharmaceutical plant | <10-103 (11-28) | 11 | 9 (82) |
| Raw sewage | Lynetten south inlet (exposed to vancomycin waste) | 103-104 (≤1) | 18 | 3 (17) |
| Raw sewage | Lynetten north inlet (not exposed to vancomycin waste) | 102-104 (≤1) | 16 | 0 |
| Raw sewage | Damhusaaen (not exposed to vancomycin waste) | 103 (≤1) | 15 | 0 |
| Raw sewage | Pharmaceutical plant (upstream) | <10-103 (<1-87) | 13 | 9 (69) |
| Raw sewage | Pharmaceutical plant (downstream) | 102-104 (<1-45) | 27 | 12 (44) |
| Activated sludge | Lynetten (exposed to vancomycin waste) | 103-104 (1-16) | 14 | 7 (50) |
| Activated sludge | Damhusaaen (not exposed to vancomycin waste) | 103 (≤1) | 14 | 0 |
| Treated sewage | Lynetten | 10−1-10 (1) | 14 | 0 |
| Treated sewage | Damhusaaen | 10−1 (1) | 12 | 0 |
| Seawater | Lynetten outlet | ≤10−2 (2) | 8 | 2 (25) |
| Sediment | Lynetten outlet | <10 ND | 3 | 0 |
| Blue mussels | Lynetten outlet | <10 ND | 4 | 2 (50) |
| Soil | Agricultural field (exposed to animal manure) | <10 ND | 2 | 2 (100) |
| Soil | Nonagricultural field (not exposed to animal manure) | <10 ND | 2 | 2 (100) |
a
Ranges of total numbers obtained from two bacteriological counts are reported for each sample type. For vancomycin sludge, numbers of colonies were higher on plates with vancomycin than on plates without vancomycin, therefore resulting in VRE percentages above 100%. ND, VRE were not detected by direct plating on SBA with vancomycin.