Assay of gentamicin concentrations in serum specimens by microbiological and radioenzymatic methods

Incidence of inducible beta-lactamases in gram-negative septicemia isolates from twenty-nine European laboratories. European Study Group on Antibiotic Resistance

In 1984 the European Study Group on Antibiotic Resistance (ESGAR), which is made up of 29 laboratories in 12 European countries, consecutively collected gram-negative bacilli and staphylococci isolates from blood and using the microdilution method performed susceptibility testing with 11 beta-lactam antibiotics. A total of 2,578 isolates were collected; 68% were gram-negatives and 32% staphylococci. Pseudomonas spp. accounted for 12% of the strains, Enterobacter spp. 7%, Serratia spp. 3%, indole-positive Proteus spp. 1%, Citrobacter spp. and Morganella spp. 0.9% each. Strains with inducible beta-lactamases were detected by the cefoxitin disc diffusion method in 11% of all gram-negatives and in 67% of the relevant species. The production of inducible beta-lactamase was confirmed by elevated MICs to and decreased killing by piperacillin, cefotaxime and ceftazidime after induction of enzyme production with low concentrations of cefoxitin. This phenomenon was not observed with mecillinam or the new penem Sch 34343.

Antimicrobial activity, beta-lactamase stability and beta-lactamase inhibition of cefotetan and other 7-alpha-methoxy beta-lactam antimicrobials

The antimicrobial activity of three 7-alpha-methoxy beta-lactams were compared to cefoperazone and ceftriaxone. All had a similar spectrum of activity against the Enterobacteriaceae, except cefoxitin. Cefotetan was only slightly less active than moxalactam against the Enterobacter spp. Ceftriaxone was most effective on Neisserias, Haemophilus spp, nonenterococcal Streptococcus spp, and Acinetobacter spp. Cefoperazone generally inhibited more pseudomonads while all of the "cephamycins" showed activity against Bacteroides fragilis and B. thetaiotaomicron. Beta-lactamase hydrolysis studies of six substrates having pharmacologic serum half lives of greater than or equal to 2 hrs were performed by bioassay and automated procedures. Excellent correlations were found between methods up to 24 hrs. A "lag-phase" was observed for several drug/enzyme combinations before initiation of significant substrate hydrolysis. The 7-alpha-methoxy beta-lactams were routinely more stable to the six representative enzymes (Richmond-Sykes types I-V) than other "stable" cephalosporins. Substrate hydrolysis rates resulting in greater than 50% drug loss in less than or equal to 1 hr generally produced resistant in vitro test results. Cefotetan, cefoxitin, moxalactam, ceftriaxone, and dicloxacillin were potent inhibitors of Type I (P99) beta-lactamases. Moxalactam demonstrated significant inhibition and affinity for the Type V enzyme while cefoperazone uniquely possesses affinity (so-called inhibition) for all tested beta-lactamases. Cefotetan appears to be a promising, beta-lactam compound with some in vitro characteristics comparable to the 1-oxa-beta-lactams and alpha-methoxyimino cephalosporins.

Cefuroxime in soft tissue infections and septicaemia

Data are presented on the absorption, antibacterial activity, clinical efficacy and side effects of cefuroxime in 33 cases with proven bacterial infection in soft tissues and in patients with septicaemia. The drug was administered mainly intramuscularly (i.m.) but also intravenously (i.v.). Peak serum concentrations 1 h after an injection of 750 mg cefuroxime i.m. were between 16-25 mug/ml. After 8 h the levels were mostly < 4 mug/ml in patients with normal renal function. I.v. injection gave only slightly higher maximum serum level obtained was approximately 40 mug/ml. No accumulation of the drug occurred in patients with normal renal function. Cefuroxime was active against all the gram-positive bacteria isolated from our patients as well as most of the gram-negatives. The clinical effect was satisfactory in 96%. The drug was well tolerated. Side effects were slight and relatively few.

Secretion of metronidazole into the human semen

The concentration of metronidazole has been studied in blood and in seminal plasma from apparently healthy volunteers and men with subclinical prostatitis. The volunteers took one dose of 500 mg orally and the patients 250 mg twice daily for two to three days. Therapeutic concentrations of metronidazole were found in blood and semen two to three h after intake. In patients the mean concentration was 8.7 micrograms/ml in blood plasma and 7.0 micrograms/ml in seminal plasma. Split ejaculates were collected in four to six fractions and the concentrations of metronidazole in the different fractions were related to those for zinc and fructose. The results indicated that the drug was excreted from prostate, seminal vesicles, and the ampulla ductus deferens.

Antibacterial activity of cefuroxime in human bone

Bone samples were taken at orthopaedic surgery from 12 patients, who had been treated with 2 doses of 750 mg cefuroxime by intravenous infusion. After grinding, extraction and assay by the agar diffusion method the levels of cefuroxime ranged between 0.4--1.9 micrograms/g bone. Using an electrophoretic method followed by microbiological assay, higher levels of cefuroxime were measured, possibly because of a diminution in the binding capacity of the bone.

Successful treatment of pseudomonas aeruginosa--ventriculitis with intraventricular gentamicin in a child with hydrocephalus

A hydrocephalic child, who was operated with a ventriculo-peritoneal shunt at the age of 1 month, developed ventriculitis due to Pseudomonas aeruginosa at 8 months. After removal of the shunt and successively increasing intramuscular and intraventricular doses of gentamicin the patient was cured and a new shunt could be inserted. As high 24-hour gentamicin level in the cerebrospinal fluid as 76 microgram/ml was reached without any apparent toxic signs.