Abstract: Cephalosporin compounds of the formula ##STR1## wherein R is 1-carboxymethyl-1,2,3,4-tetrazol-5-yl or 5-carboxymethyl-1,3,4-thiadiazol-2-yl,and non-toxic pharmaceutically acceptable salts thereof, and processes for preparing them. The compounds have superior antibacterial activity and excellent solubility in an aqueous medium, and are useful as antibacterial agent.

Abstract: A penicillin compound of the formula ##STR1## wherein R is a formyl or acetyl group, and a nontoxic pharmaceutically acceptable salt thereof. The penicillin compound is prepared by (A) reacting a compound of the formula ##STR2## or its salt or its reactive derivative at the carboxyl group, with 6-.alpha.-amino-p-hydroxybenzylpenicillin or its salt or its derivative, or reacting a compound of the formula ##STR3## or its salt or its reactive derivative at the carboxyl group, with 6-aminopenicillanic acid or its salt or its derivative, (B) optionally hydrolyzing or catalytically hydrogenolyzing the reaction product, and (C) optionally converting the reaction product to a nontoxic pharmaceutically acceptable salt. The penicillin compound has low toxicity and superior antibacterial activity especially against bacteria of the genus Pseudomonas and is suitable for parenteral administration, especially for an intramuscular, intravenous or subcutaneous injection.

Abstract: Piperazine derivatives of the following formula ##STR1## wherein A and B are a carbon atom or a nitrogen atom except the case where both A and B are nitrogen atoms,R.sub.1 is hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a benzyl group or acetyl group;R.sub.2 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a benzyl group or a vinyl group; andR.sub.3 is hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and pharmaceutically acceptable salts thereof.

Abstract: Pyrimidine compositions or their non-toxic acid-addition salts are used for preventing and treating infectious diseases of fish caused by pathogenic microorganisms.

Abstract: This invention provides compounds of the following formula ##SPC1##Wherein R.sub.1 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group having 2 to 4 carbon atoms, a benzyl group, a benzyl group subsituted by methoxy, a phenyl group, a propargyl group or an acyl group; R.sub.2 is hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkyl group having 2 to 4 carbon atoms substituted by hydroxy or halogen, a vinyl group, an allyl group, or a benzyl group R.sub.3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms;And salts thereof, and processes for preparing them. Some of the compounds have antibacterial activities.