Healthcare News & Insights

New area to focus on to reduce antibiotic resistance

Battling antibiotic resistance has been a mission of most hospitals and the medical world for years. And the focus has been on reducing unnecessary use of antibiotics and maximizing effectiveness of infection control policies. But now there’s a new area to focus on.

464848371Hospital wastewater.

It’s a “potent reservoir” of antibiotic-resistant organisms, found a new French study published online May 1 in Clinical Infectious Diseases.

And it may be a key factor fueling the spread of extended-spectrum beta-lactamase-producing escherichia coli (ESBLEC).

It would appear that ESBLEC is common in hospital and community settings. In fact, one study found that 6% of healthy adults in Paris carried the bacteria in 2011. What happens is ESBLEC enters wastewater and is routed through treatment plants. However, little data exist as to the exact levels of ESBLEC that enter or leave treatment plants.

Analyzed wastewater

The researchers took wastewater samples from 11 sites throughout the wastewater network of Besançon, a city of a quarter million people. The samples were collected and analyzed weekly during a 10-week period in 2011.

The samples included wastewater from two hospitals, sites unrelated to the hospitals, and samples collected before and after it went through the municipal wastewater treatment plant.

In addition, digested sludge derived from the wastewater, which was used to fertilize farmland, was also analyzed. The researchers found, however, that the wastewater network contained no effluent from livestock farming.

Study findings

What the researchers found was that the overall concentration of E coli was higher in urban wastewater than in hospital wastewater (7.5 × 105 vs 3.5 × 105 colony-forming units/mL, respectively).

However, the concentration of ESBLEC was 30 times higher in hospital wastewater compared with the urban samples (27 × 103 vs 0.8 × 103 colony-forming units/mL, respectively).

ESBLEC was found in almost all of the samples and it accounted for approximately 0.3% of the total E coli found in untreated water headed to the plant for treatment.

While the treatment plant did eliminate most of the E coli and ESBLEC, it didn’t eliminate all of it. After treatment, 2% of the E coli remained, and 6% of ESBLEC survived.

The researchers also found high concentrations of ESBLEC in sludge headed to farmland.

More resistant to antibiotics

An interesting finding was that when isolates were tested for antibiotic susceptibility, it was found that the ESBLEC in the hospital wastewater were more resistant to antibiotics than those in the urban wastewater.

“Our results suggest that there is a need for improvements in the monitoring of antibiotic-resistant microorganisms of human origin in effluent,” concluded the researchers.

Key component

As a result of this study, effective treatment of hospital wastewater should be a key component in efforts to stem antibiotic resistance.

“We have another opportunity to limit exposure to resistant organisms through the disinfection and treatment of hospital waste,” wrote Jeffrey Griffiths, MD, MPH, from the Department of Public Health and Community Medicine, Tufts University, Boston, and Michael Barza, MD, from the Steward Carney Hospital, Tufts University School of Medicine, in an editorial commentary accompanying the study. “What happens in hospitals should stay in hospitals!”


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