A diverse group of bacteria, the Gram-negatives include well known organisms such as E. coli, as well as increasingly important hospital pathogens such as Acinetobacter. Gram-negative bacteria account for about 30% of HAIs in the United States and an even greater proportion of infections in other parts of the world. High levels of antibiotic resistance prevail among many species of Gram-negative bacteria, and few new drugs are in the development pipeline with activity against these organisms, making Gram-negative bacteria a particularly concerning threat for the future.
CDDEP has worked on assessing changing patterns of antibiotic resistance among Gram-negative bacteria. Among Acinetobacter bacteria in hospitals, CDDEP researchers found that resistance to a last-line antibiotic more than tripled from 5% in 1999 to 18% in 2006. Among the bacteria Klebsiella pneumoniae and E. coli, resistance to commonly used antibiotics increased, particularly resistance of E. coli to a commonly used class of antibiotics known as quinolones.