TABLE 2.
Rates of medium overgrowth with nontarget microorganisms in raw and pasteurized milk cultures
| Type of milk | No. (%) of samples contaminated under the following conditionsa:
|
Total no. (%) of samples affected | ||||
|---|---|---|---|---|---|---|
| HEYM only
|
BACTEC medium only | BACTEC medium + HEYM
|
||||
| One slope | Two slopes | One slope | Two slopes | |||
| Raw | 37 | 33 (28.3) | 28 (11.3) | 7 | 16 (9.3) | 121 (48.9) |
| Pasteurized | 27 | 13 (6.9) | 152 (26.5) | 17 | 6 (4.0) | 215 (37.5) |
a
For HEYM, contamination was overgrowth of slopes by fungi and/or other non-acid-fast bacteria or blue discoloration of the slopes, which is known to inhibit the growth of M. paratuberculosis. For BACTEC medium, contamination was a mixed culture (acid-fast and non-acid-fast bacteria present together) or only non-acid-fast bacteria observed upon Ziehl-Neelsen staining of growth- positive cultures. Percentages for HEYM data are averages of data for one slope and two slopes.