Synergistic interaction between ofloxacin and cefotaxime against common clinical pathogens

Abstract

Antimicrobial synergy resulting from combined antibiotic therapy is often important in the treatment of serious bacterial infections. To investigate the interactions between cefotaxime (CTX), desacetylcefotaxime (DES), and ofloxacin (OFL), 247 recent clinical isolates were tested for in vitro susceptibility to each antibiotic alone by an agar dilution technique and retested with the various antibiotic combinations using a checkerboard protocol. Fractional inhibitory concentrations were calculated for all organisms with all drug combinations. Time kill kinetic studies were performed on selected isolates to examine the bactericidal activity of the various antimicrobial combinations. Of the 110 gram-negative organisms tested, synergy or partial synergy between CTX, DES and OFL was demonstrable for 89 (81%). Included in the study were 70 members of the Enterobacteriaceae family, 20 isolates of Pseudomonas aeruginosa, 10 strains of Acinetobacter baumannii, and 10 isolates of Xanthomonas maltophilia. Additive activity was observed against an additional 13 (11%) isolates. Findings were similar for the 89 gram-positive isolates examined. Organisms tested included methicillin-resistant Staphylococcus aureus (20), methicillin-susceptible Staphylococcus aureus (20), methicillin-resistant Staphylococcus epidermidis (9), methicillin-susceptible S. epidermidis (10), Enterococcus faecalis (10), and Streptococcus pneumoniae (20). Synergy or partial synergy was observed against 81 (91%). Less synergistic activity was detected, however, with members of the Bacteroides fragilis group. Of the 48 organisms tested, synergy or partial synergy was noted for only 27 (57%). Isolates representative of each major group of organisms included in the study were tested to determine whether synergistic bactericidal activity was also demonstrable with the three drugs. Time kill studies supported the checkerboard results.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro Interaction between Ofloxacin and Cefotaxime against Gram-Positive and Gram-Negative Bacteria Involved in Serious Infections

“…In support of previously published data [4,6], a noteworthy finding in our study was the absence of antagonism between these drugs against the various bacterial species tested, thus supporting the use of the antibiotic combination in the appropriate clinical settings, provided that further clinically relevant data are collected from new in vivo studies.…”

“…Overall, our data support previously published results [6], though a few discrepancies were encountered: the synergistic activity detected against methicillin-susceptible S. aureus and S. pneumoniae in the above-mentioned study was globally much greater than that observed in the present study. In contrast, full synergy against P. aeruginosa isolates was more frequently encountered in our study.…”

Pharmacodynamic modeling of the in vivo interaction between cefotaxime and ofloxacin by using serum ultrafiltrate inhibitory titers

“…In this study, the combination of ofloxacin and cefotaxime was found to exhibit additive antibacterial effects. Previous reports for patients and in vitro results have suggested that this combination may be synergistic (13). More than 80% of grampositive and gram-negative isolates were characterized as exhibiting synergy or partial synergy.…”

Epidemiology and antimicrobial resistance of staphylococci isolated from different infectious diseases

“…In this study the efflux mechanism in S. aureus strains was aureus strains have been previously investigated (13,16). Also the validity of DAA had been demonstrated (26,32).…”