Biocidal activity of chlorhexidine and cetrimide against various oral microorganisms

The microbicidal activity of chlorhexidine and cetrimide alone and in combination against various oral microorganisms was evaluated. The tested microorganisms were Staphylococcus aureus, Strept. viridans, Lactobacilli and C and ida albicans. The results showed that cetrimide [0.025%] potentiated the activity of chlorhexidine, and it was possible to select combinations that produce a 100% kill within five minutes. Such formulations could be of use as mouth rinses to guard against dental caries and other oral diseases such as c and idosis

Transferable drug resistance among clinical isolates of enterobacteria

Transfer of chemo-antibiotic resistance was carried out on fourteen strains of enterobacteria clinically isolated from Egyptian patients by conjugation into E. coli K.[12] recipient. All 14 strains were resistant to 4 or more antibiotics and transferred all or part of their drug resistance at a rate of 10[-3] - 10[-5]. With only 3 strains, the genetic loci coding for r-markers are located on the same plasmid representing 21.5% of the strains while partial transfer, that is segregated transfer of r-markers was observed in 78.5% of the tested strains. Ap, Cm, Km, Sm and Tc markers were more frequently transferred than Cp marker. On the other hand, Co, Gm, Po, Rif and Sxt markers were not transferred from any of the tested strains

Effect of some factors influencing curing of R-plasmids among enterobacteria

Fourteen strains of Enterobacteria, clinically isolated, were found to have multiple antibiotic resistance and harbour transferable plasmids. Curing of antibiotic resistance using ethidium bromide generally took place at low frequency with 70% of the tested strains indicating higher stability of these plasmids. The influence of pH, temperature and inoculum size, on the curing rats was studied. The effect of pH on curing was variable. pH 6 was the best for E2 and E3 while pH6 or pH8.5 was the best for the salmonella strains. The effect of temperature was also variable while the decrease in inoculum size resulted in an increase of curing frequency. The reason for such variable effects of these factors was discussed and the results led to a clue as to the etiology of R-plasmids