RESUMO
We evaluated the genetic environment of blaGES-16 found in 2 carbapenem-resistant Serratia marcescens clinical isolates recovered from patients hospitalized at a tertiary hospital located in Rio de Janeiro, Brazil. We also compared the kinetics constants for GES-16 and GES-5 against several ß-lactams. Both S. marcescens isolates showed identical PFGE pattern and carried the carbapenemase-encoding gene blaGES-16 and the extended-spectrum ß-lactamase encoding gene blaOXA-10. The blaGES-16 was inserted at the first position of a defective class 1 integron, composed by a fragmented integrase gene that lacked its attI1 recombination site, followed by dfr22, aac(6')-IIc, and aadA1 genes. This integron was located on a 30-kb nonconjugative plasmid. The GES-16 showed 2 amino acid substitutions (Gln38Glu and Gly170Ser) compared to GES-1. Kinetic analysis showed that GES-16 presented hydrolytic activity against all ß-lactams tested, except for aztreonam. Imipenem was the carbapenem more efficiently hydrolyzed (highest kcat/Km) by GES-16. The kinetic parameters of GES-16 were similar to those of GES-5. In conclusion, we identified a new GES-type enzyme with carbapenemase activity in S. marcescens. The increasing diversity of such resistance determinants confirms the ongoing evolution of these ß-lactamases towards a broader spectrum of activity.
Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Infecções por Serratia/microbiologia , Serratia marcescens/enzimologia , beta-Lactamases/genética , Substituição de Aminoácidos , Brasil , Carbapenêmicos/farmacologia , Humanos , Integrons/genética , Cinética , Mutação de Sentido Incorreto , Plasmídeos/genética , Serratia marcescens/efeitos dos fármacos , Serratia marcescens/genética , beta-Lactamas/farmacologiaRESUMO
Goat whey is normally discarded in the milk processing industry. However, several studies have addressed its biological properties and possible use in human or animal diet. The present study aimed to analysis the protein profile of goat whey to evaluate its possible oxidant, antioxidant, antibacterial, antitumour, and cytotoxic activities in vitro against human erythrocytes. Goat whey was skimmed, and crude protein extract (CPE) was obtained. Next, protein fractions (F) were obtained using ammonium sulphate precipitation method. The proteins were characterized by SDS-PAGE, two-dimensional electrophoresis and soluble protein measurements. No significant differences were observed in protein profile of CPE, F 30-60% and F 60-90%. The highest protein content was found in F 60-90% (0.41mgP/mL). All samples, except F 0-30% showed bacteriostatic activity against different bacterial strains. Only CPE at a concentration of 1000µg/mL was haemolytic against human erythrocytes. Oxidant activity against erythrocytes was not observed. Antioxidant activity was observed only for CPE. Cytotoxicity against C6 rat glioma cell line that was performed with CPE revealed tumour cell death>70% at concentrations of 0.05 and 0.1µg/mL. These results demonstrate at first time that CPE may be used as an antioxidant, bacteriostatic and cytotoxic compound against tumour cells.
Assuntos
Antibacterianos/metabolismo , Antineoplásicos/metabolismo , Leite/metabolismo , Proteômica , Proteínas do Soro do Leite/metabolismo , Animais , Antibacterianos/farmacologia , Antineoplásicos/farmacologia , Bactérias/efeitos dos fármacos , Linhagem Celular Tumoral , Eritrócitos/citologia , Eritrócitos/efeitos dos fármacos , Cabras , Hemólise/efeitos dos fármacos , Humanos , Ratos , Proteínas do Soro do Leite/farmacologiaRESUMO
In Brazil, the presence of plasmid-mediated AmpC (pAmpC)-producing isolates has been sporadically reported. We evaluated the frequency of pAmpC among 133 Enterobacteriaceae clinical isolates. The bla CMY-2-like gene was detected in a single Klebsiella pneumoniae isolate. In our study, the pAmpC frequency was very low as previously reported.