Besides characterizing the potent activity of MyxA against M. tuberculosis, we reinvestigated the spectrum of antimicrobial activity . The natural product efficiently kills Gram-positive bacteria and exerts moderate activity against Gram-negative pathogens, including an efflux-deficient strain of E. coli (Table -1). Encouragingly, MyxA also inhibited the growth of mastitis-causing pathogens Staphylococcus aureus and Streptococcus uberis and Gram-negative bovine respiratory pathogens Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni (Table -2) without causing any apparent cytotoxicity (HepG2 median cytotoxic dose CTD50 > 99 µM). Since the activity of MyxA was diminished in the presence of milk but not in the presence of serum (Table -2), subsequent profiling focused on respiratory pathogens. We determined the MIC90s (n ≥ 20) for M. haemolytica and P. multocida at 16 µg/mL and for H. somni at 8 µg/mL (Table -2 and Fig. ). These promising data reignited our interest in the Myx scaffold. We therefore set out to ensure sufficient compound supply for follow-up studies by implementing a dual strategy comprising both the myxobacterial source and the development of a route to total synthesis.