Drugs online research references
sbphrd.com
Comparative antibacterial efficacies of erythromycin, clarithromycin, and azithromycin were examined against Streptococcus pneumoniae and Haemophilus influenzae, with amoxicillin-clavulanate used as the active control. In vitro, the macrolides at twice their MICs and at concentrations achieved in humans were bacteriostatic or reduced the numbers of viable S. pneumoniae slowly, whereas amoxicillin-clavulanate showed a rapid antibacterial effect. Against H. influenzae, erythromycin, clarithromycin, and clarithromycin plus 14-hydroxy clarithromycin at twice their MICs produced a slow reduction in bacterial numbers, whereas azithromycin was bactericidal. Azithromycin at the concentrations achieved in the serum of humans was bacteriostatic, whereas erythromycin and clarithromycin were ineffective. In experimental respiratory tract infections in rats, clarithromycin (equivalent to 250 mg twice daily [b.i.d.]) and amoxicillin-clavulanate (equivalent to 500 plus 125 mg b.i.d., respectively) were highly effective against S. pneumoniae, but azithromycin (equivalent to 500 and 250 mg once daily) was significantly less effective (P < 0.01). Against H. influenzae, clarithromycin treatment (equivalent to 250 or 500 mg b.i.d.) was similar to no treatment and was significantly less effective than amoxicillin-clavulanate treatment (P < 0.01). Azithromycin demonstrated significant in vivo activity (P < 0.05) but was significantly less effective than amoxicillin-clavulanate (P < 0.05). Overall, amoxicillin-clavulanate was effective in vitro and in vivo. Clarithromycin and erythromycin were ineffective in vitro and in vivo against H. influenzae, and azithromycin (at concentrations achieved in humans) showed unreliable activity against both pathogens. These results may have clinical implications for the utility of macrolides in the empiric therapy of respiratory tract infections.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9835514&dopt=Abstract
word match zithromax online literature
Antimicrob Agents Chemother. 2000 Jun;44(6):1754-6.
Single-oral-dose azithromycin prophylaxis against experimental streptococcal or staphylococcal aortic valve endocarditis.
Tsitsika A, Pefanis A, Perdikaris GS, Donta I, Karayiannakos P, Giamarellou H.
Infectious Diseases Section, 4th Department of Medicine, Sismanoglion General Hospital, Athens University School of Medicine, Athens, Greece.
Azithromycin and ampicillin protected 94 and 72% of animals challenged with Streptococcus oralis, respectively (P = 0.177), while azithromycin and vancomycin protected 59 and 94% of the methicillin-resistant Staphylococcus aureus (MRSA)-challenged animals, respectively (P = 0.018). Azithromycin is effective in preventing experimental streptococcal endocarditis, but against MRSA it is less effective than vancomycin.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10817749&dopt=Abstract
word match zithromax online literature
pfizer.com
In 1996 and 1997, 68 hospital laboratories throughout the United States determined the beta-lactamase production and susceptibility to macrolides of 1,998 isolates of Haemophilus influenzae obtained from patients with community-acquired respiratory tract infections. The MICs at which 90% of the isolates are inhibited of azithromycin, erythromycin, and clarithromycin were 4, 8, and 16 microgram/ml, respectively. By National Committee for Clinical Laboratory Standards interpretive criteria, 99 and 78% of the isolates were susceptible to azithromycin and clarithromycin, respectively. The prevalence of beta-lactamase production was 32%.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9835536&dopt=Abstract
word match zithromax online literature
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