Alterations in dihydropteroate synthetase in cell-free extracts of sulfanilamide-resistant Neisseria meningitidis and Neisseria gonorrhoeae

Beta-lactamase plasmids and chromosomally mediated antibiotic resistance in pathogenic Neisseria species

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Synthesis of omega-(4-aminophenylsulfonamido)alkyl disulfides and thiosulfates and their activity against dihydropteroate synthetase from sulfanilamide-resistant Neisseria gonorrhoeae

A series of omega-(4-aminophenylsulfonamido)alkyl disulfides and omega-(4-aminophenylsulfonamido)alkanethiosulfates was synthesized from the reaction of p-acetamidobenzenesulfanilyl chloride and either the aminoalkyl disulfide dihydrobromide or the aminoalkyl bromide hydrobromide followed by sodium thiosulfate. Several of the compounds showed inhibitory activity against dihydropteroate synthetase isolated from a sulfanilamide-resistant strain of Neisseria gonorrhoeae of the same order of activity as that of sulfanilamide. An increase in the hydrophobic nature of the sulfanilamide structure did not increase inhibitory activity against this enzyme.

Neisseria gonorrhoeae isolated from disseminated and localised infections in pre-penicillin era. Auxotypes and antibacterial drug resistances

Interest in the evolution of gonococcal auxotrophy led to a study of 72 strains isolated between 1935 and 1948 from the urogenital tract (57 patients), the eye (two patients), and from disseminated gonococcal infections (11 patients and probably two others). Two cervical isolates with nutritional requirements for proline, arginine, histidine, and biotin were oxidase-positive, Gram-negative diplococci, but their identity as Neisseria gonorrhoeae was uncertain because they were atypically susceptible to colistin and did not produce acid in glucose media. The N gonorrhoeae strains were highly susceptible to 11 other antibacterial drugs but not to sulphadiazine. Defects of one or more pathways for the biosynthesis of methionine, proline, arginine, threonine, lysine, the branched-chain amino acids, hypoxanthine, and thiamine pyrophosphate were found in 39 of the 70 strains, including four isolated in the presulphanilamide era. Unexpectedly, methionine was required for the growth of 11 (21%) of the 52 Danish strains and for 13 (72%) of 18 strains isolated in the USA. The Danish strains included 28 (54%) that did not require any of the compounds used for differentiating auxotypes, whereas this type was represented by only three (17%) of the USA strains. None of the gonococci required uracil or other pyrimidines. This suggests that the requirements for arginine, hypoxanthine, and uracil commonly found in recent isolates from disseminated gonococcal infections probably evolved treatment with sulphonamide was replaced by penicillin.

The biology of the gonococcus

Gonorrhea has been known since antiquity. Today, this disease is the most commonly reported infectious disease in the U.S. The natural environment of the etiological agent, Neisseria gonorrhoeae, is man. In this host, the organism usually parasitizes mucosal surfaces populated by columnar epithelial cells. Under certain conditions, the gonococcus may disseminate or spread to adjacent organs. The gonococcus is well adapted to its environment and is a successful parasite. Until recently, gonococci were uniformly sensitive to penicilin. However, a plasmid encoding beta-lactamase has been identified in some isolates. Most strains exhibit specific requirements for various amino acids, vitamins, purines, and pyrimidines. Only glucose, pyruvate, and lactate are utilized as sources of energy. Glucose is dissimilated by a combination of the Entner-Doudoroff and pentose phosphate pathways. A tricarboxylic acid cycle is also present and active under certain conditions. Structurally, the cell envelope of the gonococcus resembles that of a typical Gram-negative bacterium. Gonococci are highly autolytic, especially in older cultures or after depletion of the energy source. Autolysis is not due solely to peptidoglycan hydrolysis, but appears to involve a destabilization of the outer membrane as well. Cell surface components such as pili, lipopolysaccharide, outer membrane proteins, and a capsule are associated with the virulence and pathogenicity of this organism.

Structure-activity of sulfones and sulfonamides on dihydropteroate synthetase from Neisseria meingitidis

The molecular interaction of various sulfones and sulfonamides with partially purified dihydropteroate synthetase from Neisseria meningitidis M-166 has been examined. The mode of action of the sulfones was similar to that of the sulfonamides. Both groups of drugs were competitive inhibitors of dihydropteroate synthetase with respect to p-aminobenzoate in a partially purified enzyme preparation. 4,4'-Diaminodiphenylsulfone was three times more effective than sulfadiazine and nine times more effective than sulfanilamide as a competitive inhibitor of dihydropteroate synthetase. The inhibitory activity of 4-amino-4'-acetamidodiphenylsulfone and 4-amino-4'-formamidodiphenylsulfone in this system eliminated their prior conversion to 4,4'-diaminodiphenylsulfone as a requirement for activity.

Effect of progesterone on Neisseria gonorrhoeae

The effects of progesterone on the growth of pathogenic and nonpathogenic species of Neisseria were studied in liquid cultures. Only strains of N. gonorrhoeae and N. meningitidis were highly sensitive to growth inhibition by progesterone. This inhibitory effect was either bacteriostatic or bactericidal, depending upon the ratio of progesterone concentration to cell mass. The site of progesterone inhibition appeared to be located in the cell membrane; >86% of [4-(14)C]progesterone was recovered in the lipid-containing cell fractions. Membrane preparations from N. gonorrhoeae bound progesterone more efficiently than those from progesterone-insensitive cells. In addition, progesterone significantly inhibited the activity of the membrane-associated enzymes reduced nicotinamide adenine dinucleotide oxidase and (cytochrome b) l-lactate dehydrogenase.