Continuous determination cephalosporins

Cephalosporin is determined from the proton concentration generated in a medium by using immobilized bacteria. A microbial sensor composed of a bacteria-collagen membrane reactor and a combined glass electrode was applied to the determination of cephalosporins in fermentation media. The system used for continuous determination... 

The system used for continuous determination of cephalosporins is shown in Figure 3. The reactor was a biocatalytic type... 

Reusability of the Electrode. Reusability of the microbial electrode was examined with the sample solution containing 125 r /mi of phenyl acetyl-7ADCA. The results obtained are shown in Figure 6. The cephalosporin determination was performed several times a day. However, no decrease of the potential difference was observed for a week. This system was applied to the determination of cephalosporins in a fermentation broth. Cephalosporin C in the cephalospolium acremonium broth was determined by the conventional method using high pressure liquid chromatography (HPLC) (13) and the electrochemical method. The results obtained are shown in Table 1. The relative error of the determination by the microbial electrode was within 10 %. Therefore, this system can be used for the continuous determination of cephalosporin in a fermentation broth. 

Cephalosporine Sensor. Simple, continuous methods for antibiotic determination are required for fermentation industries. Citrobacter freundii produced cephalosporinase, which catalyzes the following reaction of cephalosporin, which liberates hydrogen ions ... 

Fewer cephalosporins have been of clinical interest for oral administration. Studies of cefatrizine (BLS-640 SKF 60771) (7) have continued to determine in vitro characteristics,65-67 human pharmacokinetics,66 68,69 and clinical effectiveness.69-71 Extensive clinical trial data documented the effectiveness of cefadroxil (BLS-578 -OH cephalexin).72 Cefaclor (Lilly 99638) ( ) has been shown in in vitro studies to have better activity than cephalexin against gram-negative bacteria, especially H. influenzae. 56 60 73 7 The excellent oral absorption in mice, rats, and dogs paralleled that of cephalexin.75 Metabolism was observed in dogs76 but not in rodents. Human pharmacology studies indicated that cefaclor gave acceptable blood and urine levels.77... 

Bacteria produce chromosomally and R-plasmid (resistance factor) mediated P-lactamases. The plasmid-mediated enzymes can cross interspecific and intergeneric boundaries. This transfer of resistance via plasmid transfer between strains and even species has enhanced the problems of P-lactam antibiotic resistance. Many species previously controlled by P-lactam antibiotics are now resistant. The chromosomal P-lactamases are species specific, but can be broadly classified by substrate profile, sensitivity to inhibitors, analytical isoelectric focusing, immunological studies, and molecular weight determination. Individual enzymes may inactivate primarily penicillins, cephalosporins, or both, and the substrate specificity predetermines the antibiotic resistance of the producing strain. Some p-lactamases are produced only in the presence of the p-lactam antibiotic (inducible) and others are produced continuously (constitutive). 

Penicillin G is the drug of choice for infections caused by sensitive strains ofS. pneumoniae, but resistance is an increasing problem. Thus, for pneumococcal pneumonia, a third-generation cephalosporin or high-dose penicillin G fi.e., 20—24 million units daily by continuous intravenous infusion or in divided boluses every 2—3 hours) should be used until sensitivities are determined. 

Phosphate buffer (0.5 mM, pH 7.2) was transferred continuously to the reactor and sensing chamber. Then, 10 ml of sample solution containing various amounts of cephalosporins was transferred to the reactor at a flow rate of 2 ml/min by a peristaltic pump and the hydrogen ion concentration in the sample solution was determined by a combined pH electrode (GC-125 C, TOA Electronics Co. Tokyo) and displayed on a recorder (Model CDR-llA, TOA Electronics Co.). 

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