Two more patients have tested positive for Hepatitis B after getting treated at the HealthPlus Surgery Center in Saddle Brook.
The state closed the facility this month over bad sterilization practices.
Investigators from the State Health Department found a stretcher with a wet, red stain they say went without being disinfected.
According to officials, they also noticed rust-colored stains on surgical tools.
The report also found some workers did not wash their hands, reused IV bags and did not properly sanitize tools and trays.
Other patients may have also been exposed to HIV.
The surgery center sent letters back in December recommending 4,000 patients get blood tests to check for the potential issues.