The Center for Disease Dynamics, Economics & Policy

Unlike other drugs, fluoroquinolones are becoming less effective against CoNS

BACKGROUND

Coagulase-negative staphylococci (CoNS) are a broad group of species that commensally inhabit the human skin, mucous membranes (S. hominis, S. epidermidis), and vaginal tract (S. saprophyticus). Although they are less virulent than the coagulase-positive S. aureus and almost never pathogenic in healthy individuals, their persistence on hospital surfaces and devices has made them the most common source of bloodstream infections. Overlooked in the past because they primarily contaminated cultures, CoNS have emerged as a clinically relevant pathogen implicated in up to 30%of health care–associated sepsis.

The observed upward trend in quinolone resistance is contrary to the declining rates for other drugs. A potential explanation is the changing patterns of antibiotic use: fluoroquinolones have become the most commonly prescribed drug class in the United States since 2002, and levofloxacin use became particularly intensive after it was approved for high-dose treatment of community-acquired pneumonia in 2003.

RESISTANCE BY U.S. CENSUS DIVISION, 1999-2010