Comparative efficacies of macrolide antibiotics [erythromycin and roxithromycin] and cefadroxil in management of skin infections caused by staphylococcus aureus

The efficacy and safety of two macrolides [erythromycin and roxithromycin] and a B-lactam antibiotic [cefadroxil] were compared in management of skin and soft tissue infections caused by Staphylococcus aureus. A total of 55 cases were chosen including chronic recurrent cellulitis, furunculosis, ecthyma, pustular eruption infected burn, chronic leg ulcer and carbuncels. The mean duration of treatment was 7 days for roxithromycin therapy, 8.5 days for erythromycin therapy and 10.5 days for cefadroxil therapy. The clinical response rates were comparable for the three-treatment regimens

Effect of some additives on gentamicin production by free and immobilized cells of micromonospora purpurea

The effect of magnesium, calcium, cetrimide, ampicillin and cefotaxime on the production of gentamicin by free and immobilized cells of Micromonospora purpurea was studied. Addition of magnesium to fermentation media resulted in an increase in gentamicin production by the free cells which was directly proportional to the added magnesium. On the other hand, addition of magnesium to immobilized cells decreased the production of gentamicin. Calcium and cetrimide reduced gentamicin productivity in fermentation media of both free and immobilized cells. Addition of a sub-bacteriostatic concentration of either ampicillin or cefotaxime to free cells resulted in an increase in gentamicin production from 52.48 to 83.2 and 150 ug/ml when using both concentrations of cefotaxime. Ampicillin and cefotaxime at 0.25 and 0.5 MIC increased production of gentamicin by using immobilized cells from 83.2 to 150 and 260 ug/ml, respectively. However, the period of peak production was substantially delayed up to 9 days

Plasmid-profile in pathogenic edwardsiella ictaluri isolated from infected catfish

Thirteen strains of catfish pathogen, Edwardsiella ictaluri, were isolated from infected catfish over a period of four years from different geographic areas. All the strains were found to be susceptible to aminoglycosides, cephalosporins, penicillins, quinolones, tetracyclines, chloramphenicol, nitrofurantoin and sulfonamides. The isolated strains were examined for their plasmid contents. The plasmid profile in the channel catfish isolates of E. ictaluri consisted of one to four species of plasmids. Fewer plasmid species were observed in the strains which were isolated in earlier years and the number was progressing in the strains isolated in later years. In the non-channel catfish isolates of E. ictaluri, variable patterns of plasmid profiles were observed in the E. ictaluri strains. Such profiles were dependent on the host fish species, but at least one or two of the plasmid species were common among some of these strains. There was no detectable antibiotic resistance in any of the strains which excluded the evolvement of any of the plasmids in antibiotic resistance. Plasmid curing was studied to investigate some of the functions of these plasmids. Curing was performed by treatment with a curing agent [acridine orange, ethidium bromide, nalidixic acid] or by incubation at elevated temperature. Plasmids in E. ictaluri appeared to have virulence related functions that contribute to the pathogenicity against catfish

Enhancement of benzyl penicillin activity against staphylococcus aureus in presence of subinhibitory concentration of surfactants

Abscess causative agents were isolated from 17 patients. Sixty-four bacterial isolates were identified as Staphylococcus aureus. Fifty-seven of these S. aureus were penicillinase producers. Incorporation of subinhibitory concentrations of cetrimide or sodium dodecyl sulfate [SDS] in the nutrient agar increased the diameter of the inhibition zones of benzyl penicillin discs. Incorporation of subinhibitory concentrations of SDS in the liquid broth also decreased the MICs benzyl penicillin, ampicillin and carbenicillin against penicillinase positive S. aureus. Combining a subinhibitory concentration of cetrimide or SDS with benzyl penicillin in liquid culture of S. aureus reduced the culture turbidity and cell viability. It was evident that, surfactant at subinhibitory concentrations enhance the activity of benzyl penicillin against penicillinase producing Staphylococcus aureus

Effect of pH and human serum on the in-vitro activity of B-lactam and aminoglycoside combinations

The effect of three pH values [5.8, 7.4, and 8.0] and human serum on the activity of ampicillin, cefazolin, and cefotaxime alone and in combination with four aminoglycoside antibiotics [streptomycin, tobramycin, gentamicin, and amikacin] against sensitive and resistant strains of Staphylococcus aureus and Pseudomonas aeruginosa was evaluated. The change of pH from 5.8 to 8 noticeably affected the activity of all studied combinations. In general, the five B-lactam aminoglycoside combinations were more active at alkaline pH [pH 8]. However, pH shift towards the acidic side [pH 5.8] decreased their activity and increased their FIC indices. Addition of human serum decreased the in vitro antibacterial activity of B-lactam and aminoglycoside antibiotics, as well as their combinations against the used strains. The degree of influence was related to the ability of each antibiotic to bind with serum albumin. Cefazolin/streptomycin and cefazolin/tobramycin combinations showed the highest degree of protein binding effect

In vitro interaction of kanamycin with cefotaxime

A study was conducted to investigate the in vitro interaction between kanamycin and cefotaxime. Three aqueous concentrations of kanamycin [5, 15 and 20 ug/m1] and four concentrations of cefotaxime [100, 200, 400 and 600 ug/m1] were incubated alone and in mixtures for a period of 3 days at 37C. Samples were taken every 12 hours and analyzed for each antibiotic activity. Degradation of kanamycin in presence of different concentrations of cefotaxime was significantly greater than kanamycin alone. However, no significant difference could be traced between cefotaxime concentration and the extend of kanamycin degradation was not significantly altered in presence of kanamycin. The abovementioned findings were related to the fact that the used concentration of cefotaxime for exceeded those of kanamycin