A technique for studying the action of antiseptics on bacteria in subcutaneous tissues, with special reference to chlorhexidine

Cell Based Drug Delivery: Micrococcus luteus Loaded Neutrophils as Chlorhexidine Delivery Vehicles in a Mouse Model of Liver Abscesses in Cattle

The recent WHO report on antibiotic resistances shows a dramatic increase of microbial resistance against antibiotics. With only a few new antibiotics in the pipeline, a different drug delivery approach is urgently needed. We have obtained evidence demonstrating the effectiveness of a cell based drug delivery system that utilizes the innate immune system as targeting carrier for antibacterial drugs. In this study we show the efficient loading of neutrophil granulocytes with chlorhexidine and the complete killing of E. coli as well as Fusobacterium necrophorum in in-vitro studies. Fusobacterium necrophorum causes hepatic abscesses in cattle fed high grain diets. We also show in a mouse model that this delivery system targets infections of F. necrophorum in the liver and reduces the bacterial burden by an order of magnitude from approximately 2•106 to 1•105.

Topical antimicrobial prophylaxis in minor wounds

OBJECTIVE

To evaluate the ability of a novel topical antimicrobial gel containing cetrimide, bacitracin, and polymyxin B sulfate to prevent infections of minor wounds.

DESIGN

A clinical trial compared the test preparation with placebo and a povidone iodine antiseptic cream.

SETTING

Five primary schools in Sydney, Australia, participated in the study over a 6-week spring/summer school term.

SUBJECTS

Children aged 5-12 years with parental consent were eligible for study participation. Accidental injuries occurring at school were treated in a standardized manner by nurses at each site.

OUTCOME MEASURES

Wounds were evaluated by the medical practitioner after 3 days of topical treatment. The clinical outcome was classified as resolution or suspected infection. If a clinical infection was suspected, the injury was swabbed for microbiologic evaluation. Growth of a dominant microorganism was classified as a microbiologic infection.

RESULTS

Of the 177 injuries treated, there were nine clinical infections. A comparison of these showed a significant difference among treatment groups (p < 0.05). This difference was associated with the test preparation and placebo; the test preparation reduced the incidence of clinical infection from 12.5% to 1.6% (p < 0.05; 95% CI, 0.011 to 0.207). A comparison of microbiologic infections showed no significant differences among treatment groups (p > 0.05).

CONCLUSIONS

The novel gel preparation containing cetrimide, bacitracin, and polymyxin B sulfate showed therapeutic action and reduced the incidence of clinical infections in minor accidental wounds. It may be a suitable product for first aid prophylaxis.

THE EVALUATION AND MODIFICATION OF A TECHNIQUE FOR COMPARING THE EFFICIENCY OF ANTISEPTICS AGAINST SUBCUTANEOUSLY DEPOSITED BACTERIA IN MICE

An attempt has been made to study the action of antiseptics on artificial streptococcal ;wounds' in mice by a published technique (Martin, 1959). The results were not in agreement with those of Martin and the possible reasons for this are discussed. Suggestions are made for modifying the original method to increase its scope and precision. The production and treatment of Ps. pyocyanea and Kl. aerogenes ;wounds' in mice is described and discussed.

Infection resistance of surface modified catheters with either short-lived or prolonged activity

It has been suggested that the invasion of microbes into the catheter tract occurs mainly at the time of catheter insertion. To investigate whether the presence of an antimicrobial environment during the initial period after insertion is sufficient to reduce the risk of subsequent catheter colonization and infection, we evaluated the use of benzalkonium chloride-heparin bonded (BZK-hep) central venous catheters, which exhibit short-lived surface antimicrobial activity, using a rat subcutaneous model. Bacterial adherence on these catheters was determined, seven days after challenging the insertion site with 10(6) cfu of Staphylococcus aureus. A chlorhexidine-silver sulphadiazine impregnated catheter (Arrowg+ard), with longer lasting surface antimicrobial activity, and a hydrophilic coated catheter ('Hydrocath'), were evaluated simultaneously for comparison. Unlike Arrowg+ard antiseptic catheters, BZK-hep 'Hydrocath' and control catheters had significant bacterial adherence on their surface. Arrowg+ard catheters were colonized in 19% of the animals compared with 100% in all the other groups (P < 0.05; mean cfu cm-2: control = 1.3 x 10(6), BZK-hep = 4.3 x 10(5), Hydrocath = 2 x 10(5), Arrowg+ard = 71). Our results indicate that catheters with short-lived surface antimicrobial activity are unlikely to provide long-term protection against catheter-related infection. The efficacy of Arrowg+ard catheters may be due to the initial high rate of kill and prolonged antimicrobial activity.

An experimental evaluation of antiseptic wound irrigation

An experimental wound infection model was used to assess the value of four proprietary antiseptics applied topically in preventing the development of wound sepsis. Irrigation of wounds with either saline or noxytiolin 15 min after contamination with Staphylococcus aureus did not reduce either the incidence or degree of infection. Benzalkonium chloride and, to a lesser degree, povidone-iodine significantly reduced the infection rate, but were inferior to chlorhexidine gluconate which eliminated all overt signs of infection. The rate of healing of the chlorhexidine-treated, contaminated wounds was found to be no different from control non-infected wounds. When irrigation was carried out 45 min before wounds were contaminated, chlorhexidine was the only treatment which reduced the rate of infection (P less than 0.001). It is concluded that the superior activity of chlorhexidine in this model is a good indication that it should be a highly effective agent in the prevention of staphylococcal wound infection, and that this is probably due to a combination of bactericidal and persistent action together with low toxicity.