Naslov
Bactericidal Activity of Oral beta-lactam Antibiotics in Plasma and Urine Versus Isogenic Escherichia Coli Strains Producing Broad and Extended-Spectrum beta-lactamases.

Autori
Bedenić, Branka ; Vraneš, Jasmina

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
International Journal of Infectious Diseases (1201-9712) 8 (2004), suppl. 1 ; S172 / - , 2004

Mjesto i datum
,

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
Extended-spectrum beta-lactamases; oral beta-lactam antibiotics; Escherichia coli

Sažetak
Bacteria harboring extended-spectrum beta-lactamases (ESBLs) derived by mutation from TEM-1, TEM-2 or SHV-1 beta-lactamases have been described worldwide. The in vitro activities of these enzymes against beta-lactam antibiotics including oral cephalosporins have been previously studied. The aim of this investigation was to assess the bactericidal activity of oral beta-lactam antibiotics available at Croatian market (amoxycillin/clavulanate, cephalexin, cefuroxime, cefadroxil and ceftibuten) in biological fluids against isogenic Escherichia coli strains producing broad (TEM-1, TEM-2 and SHV-1) and ESBLs (SHV-2, SHV-3, SHV-4, SHV-5, SHV-12) in ex vivo model. Bactericidal acitivity of oral beta-lactams in plasma and urine was tested in time-kill experiments and by determination of bactericidal titers in different time intervals post dose. Plasma and urine samples were taken from health volunteers in different time intervals after receiving antibiotic. All beta-lactam antibiotics used in this study displayed strong and rapid bactericidal effect in plasma in time-kill experiments. The killing rate in urine was slower than in plasma, but faster than in Mueller-Hinton (MH) broth containing the same antibiotic concentrations. The strongest and fastest bactericidal effect in urine was observed with ceftibuten and cefuroxime, and the weakest with cephalexin. All five beta-lactams displayed strong synergystic effect with human plasma and urine. All strains used in this study were susceptible to the inherent bactericidal activity of plasma. In the presence of plasma the viable counts were strongly reduced during the first eight hours, but in all cases there was a regrowth after 24 hours. However, when plasma contained antibiotics in most cases there were no colonies already after two hours, and no regrowth after 24 hours. Bactericidal titers in plasma were significantly higher than in urine with all antibiotics used in the study. In urine bactericidal titers >1:8 were maintained throughout the whole dosing interval only for ceftibuten. Cephalexin had low titers against all tested strains already after 2 hours. Amoxycillin/clavulanate displayed very fast bactericidal activity in urine in time-kill experiments despite of low titers. According to the results of this investigation oral antibiotics apart of cephalexin should be efficient in the treatment of systemic and urinary tract infections caused by Enterobacteriaceae harbouring broad and some extended-spectrum beta-lactamases.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti, Kliničke medicinske znanosti

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