Synthesis and biological activity of a novel series of 17-azapentacyclo [6.6.5.0(2.7).0(9.14).0(15,19)]nonadeca-2,4,6,9,11,13-hexaen-16,18-dione derivatives.

In the search for novel antimicrobial agents, a series of new derivatives - N-substituted imides were prepared. All of the compounds were characterized by 'H NMR and ESI MS spectra. These derivatives were tested for antimicrobial activity. Microorganisms used in this study included aerobic and facultative anaerobic bacteria such as Staphylococcus aureus, Escherichia coli, Stenotrophomonas maltophilia, and obligatory anaerobes such as Bacteroides fragilis, Bacteroides thetaiotaomicron and Propionibacterium acnes. Moreover, Candida albicans yeast was used. For representatives of all species the MICs of the investigated compounds were determined. Most of investigated derivatives had no antimicrobial activity (MIC > 512 mg/L) except the derivative 22 which showed slight activity against Gram-positive aerobes and anaerobes.

[The correlation between phenotypes and genotypes of macrolides, lincosamides and streptogramins B resistance in Staphylococcus aureus]. / Korelacja genotypów i fenotypów opornoscina makrolidy, linkozamidy i streptograminy B u Staphylococcus aureus.

For 31 clinical strains of S. aureus the correlation between phenotype and genotype of resistance to macrolides, lincosamides and streptogramins B (MLSB) was established.. Phenotypes were determined on the basis of: susceptibility to erythromycin and clindamycin and the ability to an induction of the resistance (phenotypes S, susceptible; R , constitutive resistant, D, resistant after induction with erythromycin, D+, resistant after induction with erythromycin and with a presence of the small colonies inside inhibition zone between erythromycin and clindamycin discs), and on the basis of the resistance to spectinomycin (spR, resistant, spS, susceptible). Among examined S. aureus strains eight phenotypes of resistance to MLSB were recognized (the corresponding genotypes are given in brackets). Six phenotypes were typical: SspS (lack of MLS-B resistance genes), NEGspS (msrA/B, 1 strain), D+spS (ermCi, 4 strains),. DspR (ermAi, 11 strains and ermAi + msrA/B, 2 strains), RspR (ermAc, 4 strains and ermA + msrA/B,1 strain and ermA + ermC, 1 strain) and RspS (ermCc, 6 strains and ermB, 1 strain). Two rare phenotypes in two single strains were observed: SspR (ermAi, the strain with altered inducibility, inductor other than erythromycin) and DspS (ermAi, presumably mutation or lack of spc in Tn554).

[The frequency of the occurrence of genes ermA, ermB, ermC and msrA/B among methicillin-resistant Staphylococcus aureus strains resistant to erythromycin]. / Czestosc wystepowania genów ermA, ermB, ermC i msrA/B u metycylino-opornych klinicznych szczepów Staphylococcus aureus opornych na erytromycyne izolowanych w Polsce.

The group of 50 clinical MRSA strains resistant to MLS-B was examined for the presence of ermA, ermB, ermC, msrA/B genes by using PCR. Gene ermA was found in 43 strains (86%). 20 of ermA strains demonstrated inducible whereas 23 constitutive type of expression. The gene ermC was present in 15 of examined MRSA strains (30%). The expression of the gene was inducible in the case of 9 and constitutive in the case of 6 of the strains. The msrA/B gene was present in the case of 5 strains (10%). The ermB gene was not detected among the investigated strains.

[MIC and MBC of quinupristin/dalfopristin of erythromycin-resistant MRSA strains isolated from clinical specimens]. / Aktywnosc chinupristiny/dalfopristiny wobec erytromycyno-opornych szczepów MRSA izolowanych z materialu klinicznego.

The MICs and MBCs of quinupristin/dalfopristin were determined for 22 clinical strains MRSA with inducible type of resistance to MLS-B and for 15 of their derivatives with constitutive resistance to MLS-B. For MRSA strains with inducible resistance to MLS-B the obtained results for quinupristin/ dalfopristin were: MIC50 = 0.25, MIC90 = 0.5, MBC50 = 1.0 and MBC90 = 1.0. Mutants of the same strains characterized with the following values for quinopristin/dalfopristin: MIC50 = 0.5, MIC90 = 1.5, MBC50 = 4.0 and MTC90 = 8.0.