Plasma and peritoneal fluid concentrations of ceftriaxone after intravenous and intraperitoneal administration in horses.

Intraperitoneal (IP) use of antimicrobial agents may lead to therapeutic effects with better clinical results than intravenous (IV) administration. The aim of this study was to compare plasma and peritoneal fluid concentrations of ceftriaxone after IP and IV administration in horses, and to evaluate possible adverse effects. One group of five horses received 25mg/kg ceftriaxone diluted in 1L saline solution by IP catheter once daily for 5 days, while a second group of five horses received 25mg/kg ceftriaxone diluted in 250mL saline solution by IV injection once daily for 5days and 1L saline solution by IP catheter once daily for 5 days. Peritoneal fluid and plasma were collected to determine ceftriaxone concentrations after the first and fifth administration. IP administration of ceftriaxone resulted in concentrations above a minimum inhibitory concentration (MIC) of 1µg/mL for 24h in peritoneal fluid and for 12h in plasma, while IV administration of ceftriaxone resulted in lower peritoneal fluid concentrations, which remained above a MIC of 1µg/mL for 12h in peritoneal fluid and 10h in plasma. No adverse effects were observed. Comparisons of ceftriaxone concentrations, time of occurrence of the maximum (Tmax) and minimum (Tmin) concentrations, and the mean residence time (MRT), between the two groups showed that IP administration provided greater availability of cephalosporin in peritoneal fluid. The IP use of ceftriaxone (25mg/kg diluted in 1L saline solution once daily) may be useful for the prophylaxis and/or treatment of peritonitis in horses.

A comparative study of the binding characteristics of ceftriaxone, cefoperazone and cefsulodin to human serum albumin.

The binding to human serum albumin of three cephalosporins of pharmacological interest: cefoperazone, ceftriaxone and cefsulodin was studied by ultrafiltration and differential scanning calorimetry methods. The identification of the binding sites in albumin was also performed using probes for the so-called sites I, II, bilirubin and fatty acids binding sites. Albumin showed two types of binding sites for cefoperazone and ceftriaxone, while for cefsulodin it showed a single type of binding site. The affinity values were: 5.6 10(4) M-1 and 3.1 10(4) M-1 for cefoperazone and ceftriaxone respectively, while cefsulodin showed low affinity (3.8 10(2) M-1). It was found that only cefoperazone interacted in a slight way with site I on serum albumin, while site II and the bilirubin binding site have capacity of binding the three cephalosporins assayed. Ceftriaxone and cefoperazone showed capacity to bind to the fatty acids binding site on albumin. These cephalosporins increased the thermal stability of the protein, suggesting that these ligands are favouring the compact structure of the native form of the protein more than the unfolded form.

Non-typhoid Salmonella spp. resistant to cefotaxime.

beta-Lactamases with pIs of 5.4 and 8.1 were detected by hydrolysis of ampicillin and ceftriaxone respectively among cefotaxime resistant serovars of Salmonella spp. suggesting TEM-1 and an unidentified extended spectrum beta-lactamase have spread throughout these strains in Argentina.

Avaliaçäo da concentraçäo inibitória mínima da ceftriaxona e de aminoglicosídeos em enterobactérias em condiçöes aeróbicas e anaeróbicas / Evaluation of minimal inhibitory concentration of ceftriaxone and aminoglycosides against enterobacteria under aerobic and anaerobic conditions

Alguns trabalhos têm demonstrado que os aminoglicosídeos apresentam uma reduçäo in vitro de sua atividade frente às enterobactérias e ao S. aureus em meios anaeróbicos. O objetivo do estudo foi o de comprovar a atividade da ceftriaxona, netilmicina e gentamicina em 30 cepas de enterobactérias isoladas de infecçöes intra e extra-hospitalares, em condiçöes de anaerobiose e aerobiose. O método para a determinaçäo da MIC foi o da diluiçäo. Os resultados demonstram que a netilmicina e gentamicina perdem (em algumas cepas) a sua atividade em condiçöes de anaerobiose, o mesmo näo ocorrendo com a ceftriaxona. Esses achados sugerem que a ceftriaxona deve ser o antibiótico de eleiçäo, nas infecçöes causadas por enterobactérias onde se suspeite de baixos níveis de oxigênio