Abstract: Disclosed are 2-(syn)-hydroxyimino-acetamide derivatives of the formula: ##STR1## wherein Y is hydrogen, hydroxyl, an acyloxy, carbamoyloxy, a quaternary ammonium or a nitrogen-containing heterocyclic ring-substituted thio group; or pharmaceutically acceptable salts or esters thereof are useful as antibacterial agents. Also disclosed are processes for producing them.

Abstract: A novel cephalosporin derivative of the formula: ##STR1## [wherein X is hydrogen, hydroxyl, acyloxy, alkoxy, carbamoyloxy, quaternary ammonium or a group of the formula --SR.sup.1 (where R.sup.1 is a nitrogen-containing heterocyclic group)] or a pharmaceutically acceptable salt or ester thereof is found to have potent antibiotic activity against various bacteria, particularly against gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Proteus mirabilis, Proteus morganii, Proteus rettgeri and Citrobacter freundii.

Abstract: 2-Hydroxyiminoacetamide compounds of the following formula and salts thereof: ##STR1## [wherein X is S, O or an imino group which may optionally be substituted; B is a hydrogen atom or a hydroxyl, amino, mercapto or hydrocarbon residue group which may optionally be substituted; and COOR is a carboxyl group which may optionally be esterified] and pharmaceutically acceptable salts thereof are novel and useful as antibacterial agents.

Abstract: A novel cephalosporin derivative of the formula: ##STR1## [wherein X is hydrogen, hydroxyl, acyloxy, alkoxy, carbamoyloxy, quaternary ammonium or a group of the formula --SR.sup.1 (where R.sup.1 is a nitrogen-containing heterocyclic group)] or a pharmaceutically acceptable salt or ester thereof is found to have potent antibiotic activity against various bacteria, particularly against gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Proteus mirabilis, Proteus morganii, Proteus rettgeri and Citrobacter freundii.

Abstract: A compound of the formula: ##STR1## wherein R.sup.1 represents hydrogen or an alkyl group, X represents oxygen or sulfur or a group of formula --NR.sup.2 (where R.sup.2 is hydrogen or an alkyl group and in the case of alkyl, it may form a ring jointed with R.sup.1), and Y represents acetoxy group or a group of formula --SR.sup.3 (where R.sup.3 is a nitrogen-containing heterocyclic group), or a pharmaceutically acceptable salt thereof, is found to have a broad antimicrobial spectrum and, in particular, effective against gram-negative bacteria including Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Proteus morganii, as well as gram positive ones. Thus, these compounds may be used for antimicrobial agents in therapeutical purposes.

Abstract: Novel compounds of the formula: ##STR1## wherein X is a lower alkanoyloxy group or a substituted thio group, where the substituent is a nitrogen-containing heterocyclic group, or a pharmaceutically acceptable salt or ester thereof, have a broad antimicrobial spectrum, and besides they are readily absorbed into the living body. Thus, the compounds are useful as therapeutic agent for various bacterial infections of animals including human beings.

Abstract: Novel cephalosporin compounds of the formula ##STR1## wherein R.sup.1 is an acyl group and R.sup.2 is an alkylene group which may be substituted with a lower alkoxyl group, or pharmaceutically acceptable salt thereof, have strong inhibitory actions on broad spectra of gram-positive and gram-negative bacteria and, particularly against Esherichia coli and Klebsiella pneumoniae. Thus, the compounds are useful as therapeutic agent for various bacterial infections of animals including human beings.

Abstract: A 3-hydroxymethylcephalosporin which is not protected at the carboxyl group can be directly oxidized with a hexavalent chromium compound to give in good yield a lactol type cephalosporin represented by the general formula: ##SPC1##Wherein R.sup.1 is hydrogen or an alkoxy group and R.sup.2 is an acylamino, or imido group. The resulting compounds are very useful and important as intermediates for preparing, e.g. 3-alkoxyiminomethyl cephalosporins.