RESUMO
Strains of the facultative anaerobe Haemophilus influenzae, both type b and non typable strains, are frequently multiresistant. The measurement of the antibiotic permeability of Haemophilus influenzae outer membrane (OM) shows that antibiotics can cross through the OM easily. Thus, enzymatic activity or efflux pumps could be responsible for multiresistance. An efflux system closely related to AcrAB of Escherichia coli is present in Haemophilus influenzae. However, their role in multiresistance seems irrelevant. Classical mechanisms such as plasmid exchange seems to be playing a major role in the multidrug resistance in Haemophilus influenzae.
Assuntos
Proteínas de Transporte , Resistência Microbiana a Medicamentos/fisiologia , Resistência a Múltiplos Medicamentos/fisiologia , Proteínas de Escherichia coli , Haemophilus influenzae/efeitos dos fármacos , Antibacterianos/metabolismo , Proteínas da Membrana Bacteriana Externa/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Transporte Biológico , Transporte Biológico Ativo , Permeabilidade da Membrana Celular , Resistência Microbiana a Medicamentos/genética , Resistência a Múltiplos Medicamentos/genética , Haemophilus influenzae/genética , Haemophilus influenzae/fisiologia , Lipoproteínas/genética , Lipoproteínas/fisiologia , Proteínas de Membrana/genética , Proteínas de Membrana/fisiologia , Proteínas de Membrana Transportadoras , Proteínas Associadas à Resistência a Múltiplos Medicamentos , Fatores RRESUMO
Three different porins from Serratia marcescens were described. They were named Omp1, Omp2 and Omp3 and their molecular weights were 42, 40 and 39 kDa respectively. Omp2 and Omp3 showed osmoregulation and thermoregulation in a similar way to OmpC and OmpF of Escherichia coli. Permeability coefficients of the outer membrane of this species were calculated following the Zimmermann and Rosselet method. P values were similar to those obtained in Escherichia coli, which suggests that the chromosomal beta-lactamase would play a major role in the resistance of Serratia marcescens to beta-lactam antibiotics. Both MIC values and permeabilities were modified by salycilates and acetylsalycilate. Synergism between the outer membrane and the beta-lactamase was also evaluated. When bacteria grew in the presence of a beta-lactam in the medium, the beta-lactamase accounted for most of the resistance.
Assuntos
Proteínas da Membrana Bacteriana Externa/fisiologia , Membrana Celular/fisiologia , Resistência Microbiana a Medicamentos/fisiologia , Resistência a Múltiplos Medicamentos/fisiologia , Porinas/metabolismo , Serratia marcescens/efeitos dos fármacos , Proteínas da Membrana Bacteriana Externa/genética , Permeabilidade da Membrana Celular/efeitos dos fármacos , Cromossomos Bacterianos/genética , Resistência Microbiana a Medicamentos/genética , Resistência a Múltiplos Medicamentos/genética , Peso Molecular , Porinas/genética , Proteínas Recombinantes de Fusão/fisiologia , Salicilatos/farmacologia , Serratia marcescens/genética , Serratia marcescens/fisiologia , beta-Lactamases/genética , beta-Lactamases/fisiologiaRESUMO
Fimbriation, hemagglutination and adherence properties were studied in two strains of S. marcescens (ATCC 43820 and 43821) isolated from the urine of two hospitalized patients in two different hospitals. Studies were performed using electron microscopy (EM), fimbrial purification, recombinant DNA and hemagglutination techniques, hydrophobicity and tests of adherence to uroepithelial cells, catheters and glass. In EM, fimbriae of these two strains showed an inner channel and were 11 nm. thick and 0.76-1.08 microns long. Original strains and the clone GH42-pSF192 (recombinant DNA prepared using E. coli GH42 as recipient and the cosmid SuperCos 1 as a vector) versus negative control (E. coli GH42-SuperCos 1) showed mannose-resistant hemagglutination of tanned erythrocytes and yeast, high hydrophobicity (55.4 and 49.6% at 37C versus 22.8%) and high adherence to borosilicate glass (313,000 and 168,000 CFU/cm.2 versus 17,000 CFU/cm.2), catheters (4.7 x 10(6) and 1.0 x 10(6) CFU/cm.2 versus 3.9 x 10(4) CFU/cm.2) and uroepithelial cells (adherence indexes of 3.82 and 3.29 versus 1.25). The properties of the fimbriae studied were different from those previously described in the genus Serratia, and they were designated as MR/T.
