The invention is drawn to novel antibiotics, XENORXIDES of formula shown below, wherein R.sub.1, R.sub.2 =hydrogen, substituted or unsubstituted alkyl, cycloalkyl, acyl, aryl, aralkyl, or heterocyclyl group; R.sub.3 =hydrogen, alkyl cycloalkyl, aralkyl or aryl group, ##STR1## produced by bacterial symbiont Xenorhabdus bovienii and/or other Xenorhabdus species, and/or by oxidation of the corresponding dithiolopyrrolone derivatives with oxygen and Xenorhabdus species, and/or its cell-free filtrate, the additional salts thereof, the compositions thereof and their use as medicaments and/or agrochemicals, particularly in the treatment of infectious diseases involving microorganisms susceptible to them, including drug-resistant Staphylococcus.