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The elongated cells of Vibrio spp. induced by cephalexin treatment were examined by scanning electron microscopy. The results showed that Vibrio cholerae has a twisted cell body and a right-handed spiral conformation and that the cell bodies of V. parahaemolyticus and V. alginolyticus are straight rather than curved.
The validity of the class representative concept for in vitro susceptibility testing of older cephalosporins was reevaluated. Two oral cephalosporins, cephalexin and cefaclor, were compared with the established cephalosporin class representative, cephalothin, by using reference microdilution minimal inhibitory concentrations of 528 isolates of a wide variety of gram-positive and gram-negative bacterial pathogens. For each comparison, there were only 15 (2.8%) random major and very major interpretive discrepancies. Additional comparisons confirmed the need to test second-generation (cefamandole) and third-generation (cefotaxime) cephalosporins separately. These results provide reasonable assurance that the use of cephalothin as an in vitro predictor of qualitative bacterial susceptibility to these two oral cephalosporins remains an acceptable alternative to testing each antibiotic individually.
Cephalexin-aztreonam-arabinose agar (CAA), a new selective agar, was examined in comparison with nalidixic acid-colistin agar for the differentiation of Enterococcus faecium from other enterococci and the ability to isolate the organism from feces. Two hundred sixteen enterococcus isolates and a variety of gram-positive and gram-negative control strains were inoculated onto both media. All control strains of E. faecium were easily differentiated from Enterococcus faecalis and Enterococcus durans on the basis of arabinose fermentation on CAA. Differentiation of E. faecium from other enterococci or Streptococcus bovis was not possible on nalidixic acid-colistin agar. Increased isolation of E. faecium was demonstrated on CAA when both media were compared for the isolation of the organism from feces. CAA has been shown to possess excellent differential and selective features allowing the simple and effective isolation of E. faecium from heavily contaminated sites.
Six dogs and six cats were given a single oral tableted dose containing approximately 15 mg/kg bodyweight of the semisynthetic cephalosporin antibiotic, cephalexin. Three dogs and four cats were similarly dosed using a liquid preparation of the same antibiotic. At intervals after dosing, blood samples were taken and the level of antibiotic in the serum was determined by bioassay. After fitting the results to a mathematical model the calculated peak serum level of antibiotic was found to be about 15 micrograms/ml and to occur between one and two hours after dosing. Results agree with the performance of the antibiotic in human medicine.
A 38-year-old woman developed a generalized pustular eruption 18 h after taking an oral cephalosporin (cephalexin). After having excluded other possible pustular dermatoses, we concluded that our patient's eruption was drug-induced.
Dietary proteins are mostly absorbed as di- and tripeptides by the intestinal proton-dependent transporter PepT1. We have examined the effects of leptin on PepT1 function in rat jejunum and in monolayers of the human enterocyte-like 2 cell Caco-2. Leptin is produced by the stomach and secreted in the gut lumen. We show here that PepT1 and leptin receptors are expressed in Caco-2 and rat intestinal mucosal cells. Apical (but not basolateral) leptin increased Caco-2 cell transport of cephalexin (CFX) and glycylsarcosine (Gly-Sar), an effect that was associated with increased Gly-Sar uptake, increased membrane PepT1 protein, decreased intracellular PepT1 content, and no change in PepT1 mRNA levels. The maximal velocity (Vmax) for Gly-Sar transport was significantly increased by leptin, whereas the apparent Michaelis-Menten constant (Km) did not change. Furthermore, leptin-stimulated Gly-Sar transport was completely suppressed by colchicine, which disrupts cellular translocation of proteins to plasma membranes. Intrajejunal leptin also induced a rapid twofold increase in plasma CFX after jejunal perfusion with CFX in the rat, indicating enhanced intestinal absorption of CFX. These data revealed an unexpected action of gastric leptin in controlling ingestion of dietary proteins.
Cephalexin appears to be a highly effective antibiotic. It possesses the qualities of rapid oral absorption, production of high drug levels in the blood and urine, and near absence of side effects. It is effective against infections due to gram-positive cocci infections, with the exception of Enterococcus, and for most infections caused by E. coli and Klebsiella. It is useful in the treatment of a wide variety of infections in infants and children, and particularly valuable with susceptible infections in patients who do not require parenteral antimicrobial therapy.
The transport mechanisms of cephalexin (CEX) and ampicillin (AB-PC) across rat jejunum were examined using the electrophysiological technique in vitro. From the experiments under the short-circuit condition, it became evident that the specific transport system participates in the mucosal-to-serosal transport of CEX, while AB-PC is transport only by the simple diffusion. In addition, the transport routes of these drugs were examined using the voltage-clamp technique. Salicylate, a model drug of the weak electrolyte, was transported mainly via a paracellular route, while CEX, in the absence of Na, penetrated the membrane via two routes, i.e. the transcellular route and the paracellular route. Similar result was obtained as to AB-PC. So it seems to be likely that these two drugs diffuse through the intestinal epithelium via the similar pathways in the Na-free condition.
The effect of protein binding on the disposition of cephalexin (CEX) and cofazolin (CEZ) was investigated in a simultaneous perfusion system of rat liver and kidney. In the present study, we used bovine serum albumin (BSA) or human serum albumin (HSA) as plasma protein to control the degree of perfusate protein binding of drugs. Total clearance (CLt) of CEX perfused with BSA (0.70 +/- 0.27 ml/min) was slightly smaller than that with HSA (0.89 +/- 0.08 ml/min), corresponding to the unbound fraction of the drug in the perfusate plasma. On the other hand, CLt of CEZ perfused with BSA (0.90 +/- 0.20 ml/min) was significantly larger than that with HSA (0.32 +/- 0.10 ml/min). The unbound fraction of CEZ to BSA (0.703 +/- 0.052) was much larger than that to HSA (0.253 +/- 0.017) and the clearance of the unbound drug did not differ significantly between two kinds of albumin perfusate (1.30 +/- 0.40 ml/min for BSA and 1.26 +/- 0.40 ml/min for HSA). These results suggest that plasma protein binding is an important factor determining the biliary clearance as well as the urinary clearance of drugs.
Immunological properties of delayed-type hypersensitivity (DTH) reaction induced by cephalexin (CEX) in guinea pigs were investigated. The animals were immunized with CEX using Freund's complete adjuvant. The time course of CEX-induced erythema showed some differences compared with that of classical DTH reaction. The erythema appeared at 6 h after intradermal administration of CEX, reached maximum size at 12 to 24 h and to be visible until 72 h. By enzyme-linked immunosorbent assay, anti-CEX antibody was detected in only one of 15 animals tested. Normal animals (recipients) which had received immune sera from CEX-sensitized animals (donors) showed no skin reaction to CEX. In contrast, reaction to CEX was observed in recipient animals which had received a local transfer of lymphocytes or T cells from CEX sensitized animals. In immunopharmacological study, cyclosporin A suppressed the skin reaction but cyclophosphamide did not. Administration of carrageenan, an inhibitor of macrophage function, had no effect on expression of the reaction. Post administration (1 or 15 h) of clemastine, an anti-histamine drug, did not affect the reaction. By histological examination, the infiltrating cell-types at the reaction site were mainly composed of mononuclear cells and neutrophils, but no basophils, indicating that CEX-induced DTH reaction is tuberculin-type DTH and not a cutaneous basophil hypersensitivity reaction.
A 24-year-old woman with a history of penicillin allergy developed reversible acute renal failure after receiving cephalexin for 4 days. The patient experienced nausea, vomiting, diarrhea, pruritus, cough, and an elevated creatinine level of 2.2 mg/dl. The patient's creatinine level continued to rise, peaking at 5.3 mg/dl on hospital day 3. Nephrotoxic acute tubular necrosis was confirmed by electron microscopy. Within 1 month of discharge from the hospital, the patient's creatinine level decreased to 0.6 mg/dl. Although the renal injury most commonly associated with the cephalosporin class of antibiotics is allergic interstitial nephritis, currently available cephalosporins infrequently can cause direct tubular toxicity.
The protective activity of 3-deacetoxy-7-(alpha-amino-1-cyclohexenylacetamido) cephalosporanic acid (SCE-100) against experimental intraperitoneal infections in mice caused by several strains of Gram-positive and Gram-negative organisms, including penicillin resistant strains, was compared with that of cephalexin (CEX). Comparable protective effects by oral administration of SCE-100 and CEX were observed in mice infected with Gram-positive organisms, while in mice infected with Gram-negative organisms SCE-100 was less active than CEX. SCE-100 showed a protective effect in infections of mice with either penicillin G-resistant Staphylococcus aureus or ampicillin-resistant Escherichia coli. The oral ED50 of SCE-100 was similar to or slightly larger than the subcutaneous value.
A pharmacokinetic model has been developed, by means of which all possible time courses of the concentrations of antibiotics in the plasma of treated individuals can be exactly simulated in vitro without diluting the test organism and affecting the growth curves. Equieffective concentrations in the system corresponded to the plasma concentrations in man produced by cefroxadine in a single oral dose of 250 mg and cephalexin and cephradine in a single oral dose of 500 mg.
The Stevens-Johnson syndrome is rarely associated with hepatitis and neither entity is commonly seen following the use of ampicillin or cephalexin. An infant is described in whom both entities appeared simultaneously following therapy with these drugs.
Investigations were performed on the bactericidal activity of cephalexin (keflex) and normal cord serum (NCS) against Escherichia coli K1 strains isolated from UTI. A synergistic interaction of the antibiotic and NCS was found against the strains resistant and sensitive to the serum.
MIC of amoxicillin (AMPC), ampicillin (ABPC) and cephalexin (CEX) against bacteria detected from the patients suffering from urinary infections was determined and the clinical efficacy of AMPC was examined. As the result of determining MIC of AMPC against the detected Escherichia coli, 85.4% showed the value of less than 6.25 mcg/ml. AMPC and ABPC seem to be well correlated with each other regarding MIC, and AMPC showed 1 approximately to 2 stage lower concentration than CEX. In connection to clinical efficacy of AMPC, the oral administration at a daily dose of 750 mg gave the effectiveness rate of 92.5%. Few side effects were caused by administering AMPC and this is an excellent drug for healing acute simple urinary infections.
The extracellular penicillin acylase from Bacillus megaterium was immobilized by coupling to derivatives of polyacrylonitrile fibres. The apparent activity of the immobilized enzyme was about 153 U/g (wet weight). The optimal pH and temperature were 6.5 and 40 degrees C for synthesis of cephalexin by penicillin acylase, respectively. Whe the concentration of 7-ADCA was 4% and the ratio of PGME and 7-ADCA and 1:2, the average velocity of synthesis reaction was highest. The optimal supplied amount of immobilized penicillin acylase was 1.125 g/g 7-ADCA.. The apparent Michaelis constant for 7-ADCA was 0.162 mol/L and for PGME was 0.364 mol/L, Vmax was 0.0462 mol.L-1.min-1 at 30 degrees C and pH6.5. The remained activity was about 83.9% after operating 50 times.
The administration of a single dose of the antibacterial agent cephalexin intramuscularly to six ponies at a dose rate of 7 mg/kg was well tolerated. No reactions at the injection site were apparent. It was absorbed rapidly and reached a mean peak plasma concentration of 6.77 micrograms/ml after a mean of 1.41 hours; plasma concentrations above 2.0 and 0.5 micrograms/ml were maintained for 3.8 and 9.8 hours, respectively.