[Susceptibility to betalactam antibiotics, glycopeptides and aminoglycosides in commensal strains of erythromycin-resistant alpha-hemolytic streptococci and Gemella spp]. / Sensibilidad a antibióticos betalactámicos, glucopéptidos y aminoglucósidos en cepas comensales de estreptococos alfahemolíticos y Gemella spp. resistentes a eritromicina.

OBJECTIVE: Susceptibility to seven betalactam antibiotics, glycopeptides and aminoglycosides was investigated in 190 erythromycin-resistant alpha-hemolytic streptococci and 30 Gemella spp, mainly from normal flora. MATERIAL AND METHODS: Antimicrobial susceptibility testing was performed by a standard agar diffusion test and a standard agar dilution method according to NCCLS/CLSI criteria. RESULTS: 62.6% of alfahemolytic streptococci and 53.3% of Gemella spp. were not susceptible to penicillin (MIC50: 0,5 microg/mL). Cefuroxime was the least active cephalosporin (MIC50: 1 microg/mL and 0.5 microg/mL, in streptococci and Gemella spp., respectively), whereas cefotaxime, ceftriaxone (MIC50: 0.25 microg/mL) and cefepime (MIC50: 0.5 microg/mL) were more active than penicillin. All isolates were susceptible to vancomycin, teicoplanin and gentamicin. Four alfahemolytic streptococcal strains showed high-level resistance to streptomycin, and three strains to kanamycin. There were no significant differences in resistance rates to the antibiotics studied between strains with different macrolide resistance phenotypes. Resistance to penicillin and other betalactam antibiotics (73.8%) was prevalent in M phenotype strains and resistance to penicillin and other classes of antibiotics predominated in constitutive (cMLS(B)) strains (71.4%). CONCLUSIONS: Resistance to penicillin in erythromycin-resistant strains was notably high in this study. This fact has important clinical implications because of the endogenous character of alpha-hemolytic streptococcal and Gemella spp. infections. The lower cefuroxime activity suggests that use of this agent against other pathogens would be effective in preserving the oropharyngeal microflora analyzed.

Sensibilidad a antibióticos betalactámicos, glucopéptidos y aminoglucósidos en cepas comensales de estreptococos alfahemolíticos y Gemella spp. resistentes a eritromicina / Susceptibility to betalactam antibiotics, glycopeptides and aminoglycosides in commensal strains of erythromycin resistant alfahemolytic streptococci and Gemella spp

Objetivo. Se investigó la sensibilidad de 190 estreptococos alfahemolíticos y 30 Gemella spp., en su mayoría comensales y resistentes a eritromicina, frente a 7 antibióticos betalactámicos, glucopépticos y aminoglucósidos. Material y métodos. Para determinar la sensibilidad a los antimicrobianos se utilizaron las técnicas de dilución y difusión en agar, según las normas del National Committee for Clinical Laboratory Standards/Clinical and Laboratory Standards Institute (NCCLS/CLSI). Resultados. El 62,6% de los estreptococos alfahemolíticos y el 53,3% de Gemella spp. no fueron sensibles a penicilina (concentración inhibitoria mínima al 50% [CIM50]: 0,5 mg/ml). Cefuroxima fue la cefalosporina que presentó menor actividad (CIM50: 1 mg/ml y 0,5 mg/ml, en estreptococos y Gemella spp.), mientras que cefotaxima, ceftriaxona (CIM50: 0,25 mg/ml) y cefepima (CIM50: 0,5 mg/ml) presentaron una actividad superior a penicilina. El 100% de los aislamientos fueron sensibles a vancomicina, teicoplanina y gentamicina. Cuatro cepas de estreptococos alfahemolíticos presentaron resistencia de alto nivel a estreptomicina y tres a kanamicina. No hubo diferencia significativa en el comportamiento de los antibióticos estudiados frente a las cepas con diferente fenotipo de resistencia a macrólidos. Tanto en los aislamientos con fenotipo M como en aquéllos con fenotipo constitutivo (MLSBc) predominó la resistencia a penicilina y a otros antibióticos betalactámicos frente al patrón de resistencia, que incluye sólo penicilina o bien penicilina, otros antibióticos betalactámicos y aminoglucósidos. Conclusiones. Las tasas de resistencia a penicilina en las cepas comensales resistentes a eritromicina son particularmente elevadas, hecho que tiene una importante implicación clínica por el carácter endógeno de las infecciones causadas por estas bacterias. La menor actividad de cefuroxima podría sugerir que su utilización frente a otros patógenos preservaría en mayor grado a la microbiota orofaríngea estudiada (AU)

Objective. Susceptibility to seven betalactam antibiotics, glycopeptides and aminoglycosides was investigated in 190 erythromycin-resistant alfahemolytic streptococci and 30 Gemella spp, mainly from normal flora. Material and methods. Antimicrobial susceptibility testing was performed by a standard agar diffusion test and a standard agar dilution method according to NCCLS/CLSI criteria. Results. 62.6% of alfahemolytic streptococci and 53.3% of Gemella spp. were not susceptible to penicillin (MIC50: 0,5 mg/mL). Cefuroxime was the least active cephalosporin (MIC50: 1 mg/mL and 0.5 mg/mL, in streptococci and Gemella spp., respectively), whereas cefotaxime, ceftriaxone (MIC50: 0.25 mg/mL) and cefepime (MIC50: 0.5 mg/mL) were more active than penicillin. All isolates were susceptible to vancomycin, teicoplanin and gentamicin. Four alfahemolytic streptococcal strains showed high-level resistance to streptomycin, and three strains to kanamycin. There were no significant differences in resistance rates to the antibiotics studied between strains with different macrolide resistance phenotypes. Resistance to penicillin and other betalactam antibiotics (73.8%) was prevalent in M phenotype strains and resistance to penicillin and other classes of antibiotics predominated in constitutive (cMLSB) strains (71.4%). Conclusions. Resistance to penicillin in erythromycin-resistant strains was notably high in this study. This fact has important clinical implications because of the endogenous character of alfahemolytic streptococcal and Gemella spp. infections. The lower cefuroxime activity suggests that use of this agent against other pathogens would be effective in preserving the oropharyngeal microflora analyzed (AU)

Ligaria cuneifolia flavonoid fractions modulate cell growth of normal lymphocytes and tumor cells as well as multidrug resistant cells.

Flavonoids are ubiquitous compounds present in plant extracts. They represent a major active component of the plant extract and are often known for their anti-inflammatory and anti-tumor effects. Previously, we demonstrated that Ligaria cuneifolia (R et P) Tiegh. (Loranthaceae) extracts inhibit proliferation of murine mitogen-activated lymphocytes as well as murine T leukaemia (LB) and breast tumor cells (MMT). The aim of this study was to assess the anti-proliferative and pro-apoptotic activities of three separate flavonoid fractions derived from L. cuneifolia whole extract (aqueous, methanolic and ethyl acetate) on normal and tumor cells. This was performed as a bio-guided approach leading to the isolation and identification of the active compounds responsible for the effects observed with the whole extract. Results showed that the three fractions differed in the amount and type of compounds found. Only the ethyl acetate flavonoid fraction (100 microg/ml) was able to inhibit significantly the proliferation of Con A stimulated splenocytes or LB and MMT cells. Inhibition of proliferation was mediated by apoptosis as determined by morphology and DNA hypodiploidy. The ethyl acetate fraction modified mRNA expression of IL-2, IL-10 and TGF-beta, while the methanol fraction only modified IL-10 mRNA on LB cells. Our results show that the ethyl acetate flavonoid fraction contains the most active compound/s and is the potential candidate to isolate the active compound/s responsible for the effects observed with L. cuneifolia whole extract.

Molecular basis of resistance to macrolides and other antibiotics in commensal viridans group streptococci and Gemella spp. and transfer of resistance genes to Streptococcus pneumoniae.

We assessed the mechanisms of resistance to macrolide-lincosamide-streptogramin B (MLS(B)) antibiotics and related antibiotics in erythromycin-resistant viridans group streptococci (n = 164) and Gemella spp. (n = 28). The macrolide resistance phenotype was predominant (59.38%); all isolates with this phenotype carried the mef(A) or mef(E) gene, with mef(E) being predominant (95.36%). The erm(B) gene was always detected in strains with constitutive and inducible MLS(B) resistance and was combined with the mef(A/E) gene in 47.44% of isolates. None of the isolates carried the erm(A) subclass erm(TR), erm(A), or erm(C) genes. The mel gene was detected in all but four strains carrying the mef(A/E) gene. The tet(M) gene was found in 86.90% of tetracycline-resistant isolates and was strongly associated with the presence of the erm(B) gene. The cat(pC194) gene was detected in seven chloramphenicol-resistant Streptococcus mitis isolates, and the aph(3')-III gene was detected in four viridans group streptococcal isolates with high-level kanamycin resistance. The intTn gene was found in all isolates with the erm(B), tet(M), aph(3')-III, and cat(pC194) gene. The mef(E) and mel genes were successfully transferred from both groups of bacteria to Streptococcus pneumoniae R6 by transformation. Viridans group streptococci and Gemella spp. seem to be important reservoirs of resistance genes.

A novel trypsin inhibitor from Peltophorum dubium seeds, with lectin-like properties, triggers rat lymphoma cell apoptosis.

A trypsin inhibitor (PDTI) was isolated from Peltophorum dubium seeds by affinity chromatography on a thyroglobulin-agarose or a trypsin-agarose column. In both cases, SDS-PAGE showed two bands of M(r) 20,000 and 22,000, which could not be resolved. Their amino-terminal sequences were identical and similar to that of Kunitz-type soybean trypsin inhibitor (SBTI). Mass spectrometry analysis of tryptic digests of both bands showed 16 coincident peaks, suggesting that they are closely related proteins. The K(i)s for trypsin and chymotrypsin inhibitory activity of PDTI were 1.6 x 10(-7) and 1.3 x 10(-5)M, respectively. Lectin-like activity of PDTI and SBTI, detected by hemagglutination of rabbit erythrocytes, was inhibited by sialic acid-containing compounds. PDTI and SBTI caused apoptosis of Nb2 rat lymphoma cells, demonstrated by decrease of viability, DNA hypodiploidy, DNA fragmentation, and caspase-3-like activity. They had no effect on normal mouse splenocytes or lymphocytes, whereas they caused apoptosis of concanavalin A-stimulated mouse lymphocytes.