Blog | Wednesday, September 26, 2012

QD: News Every Day--Ciprofloxacin associated with increased MRSA in hospitals

A decrease in hospital-wide ciprofloxacin (a fluoroquinolone) prescribing was strongly associated with an overall decrease in MRSA infection, a study found.

Researchers investigated the evolution of methicillin-resistant Staphylococcus aureus over a 10-year span at St. George's, a large, acute-care teaching hospital in London over a 10-year period.

Results appeared in the Journal of Antimicrobial Chempotherapy.

Three clones caused the majority of infections, CC30 SCCmecII (EMRSA-16), CC22 SCCmecIV (EMRSA-15) and ST239 SCCmecIII.

The only substantial hospital-wide change to antibiotic prescribing occurred in 2007, when ciprofloxacin and cephalosporins were cut back. The timing of this decrease coincided very closely with the decrease in MRSA incidence in mid-2007, the researchers noted.

However, the decline in prescribing of cephalosporins was compensated for by an increase in the prescribing of other b-lactamase resistant b-lactams, such as co-amoxiclav and piperacillin/taxobactam.

Hospital clones of MRSA were nearly universally resistant to ciprofloxacin and maintained this resistance during the span of the study. Researchers wrote, "A possible explanation is that the hospital-wide prescribing of antibiotics to which MRSA is universally resistant, such as ciprofloxacin and b-lactamase-resistant b-lactams, selects for MRSA in colonized patients. This selection would lead to a higher likelihood of endogenous infection. If so, this could link the decrease in prescribing of ciprofloxacin with the decline in MRSA infection incidence."