Hospital sewers may be breeding grounds for dangerous superbugs, study finds

A Swedish study found that wastewater from hospitals can encourage antibiotic-resistant bacteria to grow, raising concern that hospital sewers may help antimicrobial resistance develop. The findings matter because resistant infections are harder to treat, although the study did not establish that sewer growth leads to infections in people.

Researchers tested wastewater from 10 hospitals and eight municipal treatment plants. After removing existing bacteria, all 10 hospital samples favoured growth of E. coli resistant to ciprofloxacin and cefotaxime; none of the municipal samples did. Bacteria on surfaces inside hospital sewer pipes were about three times as likely to resist those drugs as bacteria in the surrounding wastewater after 30 days. The study was limited to sites in Sweden, a small selection of bacteria and antibiotics, and a short observation period.