C. Diff Outbreaks Caused by Overuse of Antibiotics, Not Hospital Environments

The overuse of certain antibiotics may be the cause of clostridium difficile (C. Diff) rather than other, traditionally held beliefs about the infection, according to a study published in The Lancet Infectious Diseases (Published online ahead of print January 24, 2017. Lancet Infect Dis. doi: 10.1016/S1473-3099(16)30514-X).

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Following a number of severe outbreaks in 2006, the NHS implemented a number of national control policies to help manage the risk of C. Diff that reduced national incidence by approximately 80%.

In a study led by Kate E Dingle, PhD, Nuffield Department of Clinical Medicine, Oxford University (Oxford, UK), researchers analyzed national data for incidence of C Diff infections and antimicrobial prescribing data to determine whether the decline in C. Diff was driven by improvements in hospital infection control programs, or by reductions in the use of antibiotics, particularly fluoroquinolones.

Researchers gathered whole genome sequences from 4045 national and international C. Diff isolates. They used statistical analyses to determine which infections were due to the use of particular antibiotics and which were more likely to be caused by conditions within the health care facility.

In the vast majority of cases, researchers found that the restriction of fluoroquinolones reduced the number of antibiotic-resistant C. Diff cases by more than 80%. In fact, the proportion of C. Diff infections that were antibiotic resistant fell from 67% in September 2006 to only ~3% in February 2013. In contrast, the number of of cases not resistant to fluoroquinolone antibiotics did not change. Further, the number of infections transmitted between individuals at hospitals also did not change despite the implementation of comprehensive infection prevention and control measures.

Therefore, authors of the study concluded that widespread overuse of fluoroquinolone antibiotics allowed C Diff infections resistant to the drugs to thrive by killing off non-resistant bugs in the gut and clearing the way for rapid growth of resistant C. Diff. Thus, the restriction of these drugs does more to explain the decline in C Diff infections than other measures implemented at health care facilities.  

"Our results mean that we now understand much more about what really drove the UK epidemic of C. diff infection in the mid-2000s,” co-author Mark Wilcox, Professor of Microbiology, University of Leeds, said in a press release. “Crucially, part of the reason why some C. diff strains cause so many infections is because they find a way to exploit modern medical practice. Similar C. diff bugs that affected the UK have spread around the world, and so it is plausible that targeted antibiotic control could help achieve large reductions in C. diff infections in other countries."

However, he and other authors of the study also wrote that while overuse of antibiotics may be the chief cause of resistant C. Diff infections, providers should continue to practice good hand hygiene in order to control the spread of other infections.—Sean McGuire