Comparative in vitro activity of gemifloxacin against gram-positive and gram-negative clinical isolates in Argentina.

The in vitro activity of gemifloxacin against 1,000 clinical isolates of 147 Streptococcus pneumoniae (115, penicilin susceptible; 26, intermediate penicillin-resistant and 6, penicillin-resistant), 127 Hemophilus influenzae (109, beta lactamasa non-producer; 18, beta lactamase producers), 95 Streptococcus pyogenes (6, azytromycin-resistant), 84 Moraxella catarrhalis (79, beta lactamase producers), 110 Staphilococcus aureus (89, methicillin-susceptible; 21, methicilin-resistant), 98 Eenterococcus faecalis and 339 Enterobacteriacea, (recovered from patients with respiratory tract infection; skin and soft tissue infection and urinary tract infection), was compared with the activities of four fluorquinolones and five other antimicrobial agents. Of the quinolones tested, gemifloxacin was the most potent against Streptococcus pneumoniae, including penicillin intermediate and resistant strains. Mic(90) values obtained for gemifloxacin, ciprofloxacin, ofloxacin, levofloxacin and trvafloxacin were 0.03, 2, 2, 1 and 0.25 mg/L respectively. Gemifloxacin was 16 fold more potent than ciprofloxacin against methicillin-susceptible Staphylococcus aureus and 32 fold more potent than ciprofloxacin against Streptococcus pyogenes. When tested against Hemophilus influenzae, Moraxella catarrhalis and Enterobacteriaceae, all the quinolones showed similar activity. Our results demonstrate that gemifloxacin has similar activity than the other quinolones tested against Gram-negative organisms and is considerably more potent against Gram-positive organisms.

Argentinian collaborative study on prevalence of erythromycin and penicillin susceptibility in Streptococcus pyogenes. The Argentinian Streptococcus Study Group.

Two monthly studies on the prevalence of penicillin and erythromycin susceptibility of Streptococcus pyogenes were performed in May and October of 1994 in Argentina. A total of 58 centers from 27 cities participated in these studies. A total of 1072 isolates were tested by a diffusion method, although 595 isolates were tested both by the diffusion and an agar dilution method (n = 1767 isolates). No penicillin-resistant streptococci were found in our study (MIC100 = 0.03 microgram/ml). Only four isolates were confirmed as erythromycin resistant S. pyogenes (prevalence 0.14 and 0.28% in May and October 1994, respectively). Resistance in three isolates was due to an inducible mechanism, although in one strain a different phenotype was observed.

A ten-laboratory study of lomefloxacin (NY-198 or SC 47111) antimicrobial activity in Argentina.

The antimicrobial activity of a new fluoro-quinolone, lomefloxacin (NY-198, SC47111), was evaluated by standardized susceptibility testing methods at ten laboratories in Argentina. Lomefloxacin was found to be the most active drug against 1,316 recent clinical isolates compared directly to norfloxacin, co-trimoxazole, and gentamicin. Only 1.4% of Enterobacteriaceae were lomefloxacin-resistant (MIC greater than 4 micrograms/ml), and the lomefloxacin MIC90 for all staphylococci was 2 micrograms/ml, including methicillin-resistant isolates. Streptococci, enterococci, and some Pseudomonads (9% resistance) were less susceptible to lomefloxacin. Lomefloxacin was the most active against Neisseria gonorrhoeae strains compared to penicillin, cefuroxime, and spectinomycin. Among the tested Mycobacteria, only the nontuberculosis, slow growers had lomefloxacin MICs of greater than 4 micrograms/ml.