VANCOUVER, B.C. - Fluoroquinolone use increased the risk of B1-strain Clostridium difficile infection, a strain that is associated with severe disease and has caused outbreaks in hospitals throughout North America and Europe, according to a study at a Veterans Affairs hospital.
"We were able to demonstrate that patients in our hospital who developed CDI due to the epidemic B1 strain were more likely than patients infected with other strains to have been treated with fluoroquinolones prior to developing CDI," and that the B1 strain is highly resistant to fluoroquinolones, said Dr. Stuart Johnson, an infectious disease specialist at Loyola University, Chicago, and Hines (Ill.) VA Hospital, who presented the study at the annual meeting of the Infectious Diseases Society of America.
Dr. Stuart Johnson
"We were using [the fluoroquinolone] ciprofloxacin for many years until we knew that this was a risk for C. difficile; all the fluoroquinolones have this particular risk," he said.
Dr. Johnson said the findings mimic those of the 1990s, when he and his colleagues found that the J strain of the pathogen was highly resistant to clindamycin and was associated with outbreaks in hospitals that used clindamycin heavily (N. Engl. J. Med. 1999;341:1645-51).
"In those instances, restriction of clindamycin was very effective in interrupting outbreaks," he said.
In general, "if you are having an outbreak or increased rates of C. difficile, you may be able to target antibiotic stewardship programs to those antibiotics that are leading to the outbreak," Dr. Johnson said.
In a case-control study funded by the Department of Veterans Affairs, stool samples from newly diagnosed CDI patients at the Hines VA Hospital were cultured and typed by restriction endonuclease analysis. Patients’ antibiotic exposures over the previous 6 weeks were then checked.
Fluoroquinolone use was more frequent in the 67 patients who developed B1-strain CDI, and greatly increased their risk for a B1 infection (odds ratio, 3.6; 95% confidence interval, 1.3-9.8; P = .01).
Clindamycin use was more frequent in the 30 patients who developed non–B1-strain CDI.
B1 isolates demonstrated high-level resistance to azithromycin and moxifloxacin, a newer generation fluoroquinolone. Non-B1 isolates demonstrated high-level clindamycin resistance. All strains were resistant to ceftriaxone, but none were resistant to piperacillin/tazobactam, Dr. Johnson said.
In a separate abstract presented at the meeting by Dr. Dimitri Drekonja, an infectious disease specialist at the Minneapolis VA Medical Center, 51 of 89 patients with CDI received at least one course of antibiotics within 30 days of completing CDI treatment.
"Roughly one-third of all antimicrobial use was judged to be inappropriate" in a preliminary analysis, he said. Pending additional investigation, however, Dr. Drekonja did not provide additional details.
Dr. Drekonja said he has no disclosures. Dr. Johnson said he is a consultant for Optimer Pharmaceuticals Inc., Viropharma Inc., Novartis, Cubist Pharmaceuticals Inc., and Bio-K+ International Inc.