A five-year multicenter study of the susceptibility of the Bacteroides fragilis group isolates to cephalosporins, cephamins, penicillins, clindamycin, and metronidazole in the United States

Over 2800 clinical strains of the Bacteroides fragilis group were collected during a 5-year period from ten geographically separate sites and tested for their susceptibility to various antimicrobial agents using a broth microdilution method. Among the cephalosporins, ceftizoxime was the most active (13% resistance) and importantly exhibited relatively equal activity against both B. fragilis species and non-B. fragilis species. Cefotaxime exhibited similar activity with an overall resistance rate of 18%. Both ceftriaxone and cefoperazone were appreciably less active cephalosporins especially against non-B. fragilis species. With regard to cephamycins, cefoxitin (MIC90, 32 [mu]g/ml) was more active than cefotetan (MIC90, [ges]256 [mu]g/ml) and cefmetazole (MIC90, 64 [mu]g/ml). Non-B. fragilis species were highly resistant to cefotetan and cefmetazole. Imipenem was highly active against all strains with the exception of four strains of B. fragilis. Ampicillin-sulbactam, amoxicillin-clavulanate, piperacillin-tazobactam, and cefoperazone-sulbactam were all highly active with resistance rates <2%. No resistance was detected to metronidazole, whereas 14% of isolates were resistant to clindamycin. When compared with other studies, these findings underscore the wide variability in susceptibility patterns reported nationwide and the need to continue monitoring these patterns to aid in choosing the most active compounds for therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31666/1/0000601.pd

Bioactivity of gentamicin in purulent sputum from patients with cystic fibrosis or bronchiectasis: Comparison with activity in serum

Two mechanisms of potential biologic antagonism of gentamicin in purulent sputum from patients with cystic fibrosis or bronchiectasis were studied: reduction of activity by ions and antibiotic binding. Antagonism by ions was assessed by examination of the activity of gentamicin against Pseudomonas aeruginosa in dialysates of serum or sputum in ion-depleted broth. The ionic content of the dialysates increased and reflected differences in the ion content of serum and sputum. Gentamicin had significantly less activity against P aeruginosa in sputum or serum dialysates than in ion-depleted broth alone. When gentamicin was mixed with serum or sputum before dialysis, the level of antipseudomonas activity of the sputum dialysates was significantly lower than that of the serum dialysate; this finding was correlated with greater binding by sputum. Thus, both binding and antagonism by ions evidently reduce the level of bioactivity of gentamicin in serum and in sputum. Purulent sputum, whether from children with cystic fibrosis or adults which bronchiectasis, is more inhibitory than serum; the greater degree of binding, rather than differences in the composition or quantity of cations, explains this difference. © 1983 by The University of Chicago.SCOPUS: ar.jinfo:eu-repo/semantics/publishe