To assess the clinical importance of emergence of beta-lactam resistance caused by stable derepression of chromosomal beta-lactamases, sequential cultures from patients treated with expanded-spectrum cephalosporins were monitored for the persistence of bacteria possessing these enzymes. Antibiotic susceptibilities and beta-lactamase production before and after cefoxitin induction were determined in sequential isolates of individual bacterial strains. Of 49 strains isolated from 44 patients, 25 strains (51%) were eradicated by cephalosporin therapy, 17 strains (35%) persisted with unchanged susceptibility in sequential cultures, and 7 strains (14%) from 7 patients developed multiple beta-lactam resistance during cephalosporin therapy. In 6 of the 7 strains, resistance was associated with stable derepression of beta-lactamases. In the patient group whose strains developed resistance, subsequent use of non-beta-lactam antibiotics was more frequent and mortality was higher.
A man was hospitalized with bacteremic Achromobacter xylosoxidans type IIIa pneumonia. The authors are aware of no previously reported similar infections caused by this bacterium. A clinical cure was achieved with a combination of carbenicillin and kanamycin therapy. Microtiter susceptibility testing revealed that carbenicillin was the antibiotic to which A. xylosoxidans IIIa was most sensitive (minimal inhibitory concentration, 1.6 microgram/ml) and that synergy between carbenicillin and kanamycin existed. During the patient's hospitalization, deficiency of IgM (21 mg/dl) was found. Specific serum activity against A. xylosoxidans IIIa was detected by the agglutination method. Specific anti-A. xylosoxidans IIIa IgG, but not IgM, was detected by indirect immunofluorescence. It appears that a defect in immunologic recognition of A. xylosoxidans IIIa as an invasive bacterium, a defect in synthesis of specific IgM, or both, contributed to this patient's infection.
The plasma and urine concentrations of cefaclor were measured after oral administration of single and multiple doses to volunteers. Cefaclor was rapidly absorbed, rapidly excreted in the urine, well tolerated without toxicity, and failed to accumulate in the plasma with chronic dosing.
Distinctive lesions occurred in the brainstem of a 59-year-old patient who had had recent Pseudomonas aeruginosa meningitis treated with parenteral and intrathecal gentamicin sulfate. The lesions were multiple, minute, and discrete, and were characterized by loss of axons, spongiosis, axonal swelling with frequent calcification, loss of astroglia and oligodendroglia, and slight inflammatory response. These lesions were restricted to the myelinated fiber bundles of the pons and mesencephalon. Because similar lesions can occur with other intrathecally administered medications and emboli to the brain, an experimental study in rabbits was done. Similar lesions were produced in normal adult rabbits after a single intracisternal injection of gentamicin sulfate with or without preservative at doses equivalent to 50 and 100 times the human therapeutic dose. Lesions were not seen after injection of normal saline, preservative, or gentamicin sulfate with preservative at doses equivalent to 1 and 10 times the human therapeutic dose. A direct relationship was observed between the cerebrospinal fluid concentrations of gentamicin, brain tissue concentrations of gentamicin, and occurrence of the lesions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.