Genetic analysis of drug resistance in Neisseria gonorrhoeae: production of increased resistance by the combination of two antibiotic resistance loci

Genetic analysis of drug resistance in Neisseria gonorrhoeae: production of increased resistance by the combination of two antibiotic resistance loci.

The studies reported here demonstrate that increased resistance of Neisseria gonorrhoeae to penicillin, tetracycline, and chloramphenicol results from the combined effect of two resistance loci. As shown by experiments with deoxyribonucleic acid from transformants carrying only a single resistance locus, transformants with an incresed level of resistance to penicillin result from the combinatio...

Multiple antibiotic resistance in Neisseria gonorrhoeae.

The sensitivities of gonococcal isolates to six antibiotics were determined for gonococci isolated in Philadelphia in 1972. The degree of association between susceptibilities to any two antibiotics was determined (coefficient of correlation). The correlation between penicillin and tetracycline (r = 0.75) was almost as good as that between two penicillins, penicillin G and ampicillin (r = 0.85),...

Genetic analysis of spontaneous resistance to ampicillin in Neisseria gonorrhoeae.

Step-wise intrinsic resistance to ampicillin in Neisseria gonorrhoeae was analyzed genetically by DNA-mediated transformation experiments. A first-step ampicillin-resistant (Ampr1) mutant and a second-step ampicillin-resistant (Ampr2) mutant generated during sequential selection were used in these studies. Each selection step was accompanied by an approximate twofold increase in resistance. Fou...

The changing pattern of antibiotic resistance of Neisseria gonorrhoeae.

Prevalence of multiple antibiotic resistance in Neisseria gonorrhoeae.

The susceptibility of 100 strains of Neisseria gonorrhoeae to five antimicrobial agents (penicillin, streptomycin, oxytetracycline, sulphamethoxazole, and gentamicin) was examined. Three strains were resistant to each antimicrobial, fourteen exhibited resistance to three or four of the five compounds tested, and 49 were resistant to a single agent, or to pairs of the selected agents. 34 strains...