DQ-2556 is a recently developed
cephalosporin with a broad spectrum of antibacterial activity against both gram-positive and gram-negative bacteria. Its in vitro activity was roughly comparable to those of
cefuzonam and
cefpirome and greater than those of
ceftazidime,
cefepime, and
cefclidin against gram-positive bacteria. Against gram-negative bacteria,
DQ-2556 showed almost the same activity as those shown by
cefpirome and
cefepime. The activity was largely unaffected by culture medium pH or the addition of human serum. The protective effect of
DQ-2556 in experimental gram-positive pathogen and
Escherichia coli infections in mice was greater than those of
ceftazidime,
cefuzonam,
cefepime, and
cefclidin and was similar to that of
cefpirome. Against Pseudomonas aeruginosa and Acinetobacter calcoaceticus
infections,
DQ-2556 was more active than
cefuzonam and had activity similar to or less than those of
ceftazidime,
cefpirome,
cefepime, and
cefclidin. When cells of E. coli were exposed to various concentrations of
DQ-2556, filamentous cells were observed at concentrations of 0.0008 micrograms/ml and greater, spheroplasts started to form at 0.025 micrograms/ml, and subsequent cell lysis was observed. The affinity of
DQ-2556 to PBP 3 of E. coli, which participates in septum formation, as suggested by morphological observation, was two times greater than that of
ceftazidime.
DQ-2556 also had high affinities for PBPs 1B and 1A of E. coli. These results suggest that
DQ-2556 is worthy for subsequent clinical trials.