Table 2. Microbiological results of stool, food and environmental samples, Listeria monocytogenes outbreak, Italy, May 2016 (n = 23).
| Cluster | Number of tested samples | Material sampled | Sampling place | Qualitative analysis (in 25 g) |
Quantitative analysis | Serotype | PFGE profile (AscI/ApaI) | MLST |
|---|---|---|---|---|---|---|---|---|
| 1 | 1 | Beef ham/retention sample (batch no. 127529) |
Mass catering food service school A | Absence | < 10 cfu/g | ND | ND | ND |
| 1 | 1 | Beef ham/unopened batch (no. 127529) |
Producer | Presence | > 15,000 cfu/g | 1/2a | GX6A16.0119 / GX6A12.0305 | ST11 |
| 1 | 4 | Stool specimens | Hospital | Presence | ND | 1/2a | GX6A16.0119 / GX6A12.0305 | ST11 |
| 2 | 1 | Beef ham/retention sample (batch no. 130578) |
Mass catering food service school B | Presence | 15,000 cfu/g | 1/2a | GX6A16.0119 / GX6A12.0305 | ST11 |
| 2 | 1 | Beef ham/unopened batch (no. 130578) |
Producer | Absence | < 10 cfu/g | ND | ND | ND |
| 2 | 5 | Environmental samples | Mass catering food service school B | Absence | ND | ND | ND | ND |
| 2 | 1 | Stool specimen | Hospital | Presence | ND | 1/2a | GX6A16.0119 / GX6A12.0305 | ST11 |
| 1 and 2 | 7 | Environmental samples | Producer | Absence | ND | ND | ND | ND |
| 1 and 2 | 1 | Environmental sample (cutter machine) | Producer | Presence | ND | 1/2a | GX6A16.0119 / GX6A12.0305 | ST11 |
| 1 and 2 | 1 | Environmental sample (fridge handle) | Producer | Presence | ND | 1/2b | GX6A16.0024 / GX6A12.0306 | ST5 |
cfu: colony-forming units; MLST: multilocus sequence type; ND: not done; PFGE: pulsed-field gel electrophoresis.