Albomycin belongs to the class of
sideromycins, compounds composed of
iron carriers linked to
antibiotic moieties.
Albomycin was found to be active against bacteria that have a functional
ferric hydroxamate transport system meaning that bacteria will actively transport
albomycin until they die. We examined the activity spectrum of
albomycin for bacterial pathogens and found that Enterobacteriaceae except species of Proteus and Morganella were sensitive. Resistance in the two genera was due to the lack of the
ferric hydroxamate transport system. Among Gram-positive bacteria, Staphylococcus aureus and Streptococcus pneumoniae were highly sensitive, whereas Streptococcus agalactiae, Streptococcus pyogenes, and Staphylococcus epidermidis were resistant. The in vivo efficacy of
albomycin was examined in mice infected with S. pneumoniae or Yersinia enterocolitica. A single dose of 10mg
albomycin/kg
body weight reduced the colony-forming units of Y. enterocolitica by three to four orders of magnitude. A single dose of 1mg
albomycin/kg
body weight was sufficient to clear S. pneumoniae
infections in mice. In direct competition experiments with wild-type S. pneumoniae and its
albomycin-resistant mutant, the recovery rate of the mutant was lower than for the wild-type indicating that the mutant had reduced fitness in the mouse model. We conclude that
albomycin is effective in clearing
infections caused by both Gram-positive and Gram-negative bacteria in a mouse model.
Albomycin treatment reduces the bacterial load allowing the immune system to remove residual
albomycin-resistant bacteria, and as such would make
albomycin-based
antibiotics an adjunct to treatment. The
ferrichrome transport system serves as a Trojan horse to get
albomycin into bacteria.