Table 2.
Distribution of MSSA-positive and ‑negative wastewater samples at all WWTPs by sampling event and sampling location.
| Sampling location (total samples collected) | Mid-Atlantic WWTP1 (n = 12) | Mid-Atlantic WWTP2 (n = 8) | Midwest WWTP1 (n = 12) | Midwest WWTP2 (n = 12) | Total positive samples (%) | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Oct 2009 | Dec 2009A | Dec 2009B | Oct 2010A | Oct 2010B | Jul 2010 | Sep 2010 | Oct 2010 | Jul 2010 | Aug 2010 | Sep 2010 | Oct 2010 | |||||||||||||||
| Influent (n = 12) | Pos | Pos | Pos | Pos | Pos | Pos | Neg | Pos | Pos | Pos | Neg | Pos | 10/12 (83) | |||||||||||||
| Activated sludge reactor (n = 5) | Pos | Pos | Pos | Pos | Pos | — | — | — | — | — | — | — | 5/5 (100) | |||||||||||||
| Post aeration (n = 3) | — | — | — | — | — | Pos | Pos | Pos | — | — | — | — | 3/3 (100) | |||||||||||||
| Cell B (n = 4) | — | — | — | — | — | — | — | — | Pos | Neg | Neg | Neg | 1/4 (25) | |||||||||||||
| Secondary clarifier (n = 8) | Neg | Pos | Pos | Neg | Neg | Pos | Neg | Pos | — | — | — | — | 4/8 (50) | |||||||||||||
| Effluent (n = 12) | Neg | Neg | Neg | Neg | Neg | Neg | Posa | Posa | Neg | Neg | Neg | Neg | 2/12 (17) | |||||||||||||
| Total positive samples (%) | 2/4 (50) | 3/4 (75) | 3/4 (75) | 2/4 (50) | 2/4 (50) | 3/4 (75) | 2/4 (50) | 4/4 (100) | 2/3 (67) | 1/3 (33) | 0/3 (0) | 1/3 (33) | 24/44 (55) | |||||||||||||
| Abbreviations: Neg, negative sample; Pos, positive sample. Samples were collected twice during December 2009 at Mid‑Atlantic WWTP1 (A and B) and twice during October 2010 at Mid-Atlantic WWTP2 (A and B). aSamples were collected when seasonal chlorination was not taking place. | ||||||||||||||||||||||||||