agar and Skin-Diseases--Infectious

Fungal infections are the most frequent dermatoses. The gold standard treatment for dermatophytosis is the squalene epoxidase (SQLE) inhibitor terbinafine. Pathogenic dermatophytes resistant to terbinafine are an emerging global threat. Here, we determine the proportion of resistant fungal skin infections, analyse the molecular mechanisms of terbinafine resistance, and validate a method for its reliable rapid identification.. Between 2013 and 2021, we screened 5634 consecutively isolated Trichophyton for antifungal resistance determined by hyphal growth on Sabouraud dextrose agar medium containing 0.2 μg/mL terbinafine. All Trichophyton isolates with preserved growth capacity in the presence of terbinafine underwent SQLE sequencing. Minimum inhibitory concentrations (MICs) were determined by the broth microdilution method.. Based on our data, we propose MIC of 0.015 μg/mL as a minimum breakpoint for predicting clinically relevant terbinafine treatment failure to standard oral dosing for dermatophyte infections. We further propose growth on Sabouraud dextrose agar medium containing 0.2 μg/mL terbinafine and SQLE sequencing as fungal sporulation-independent methods for rapid and reliable detection of terbinafine resistance.

Topics: Agar; Antifungal Agents; Arthrodermataceae; Glucose; Humans; Microbial Sensitivity Tests; Skin Diseases, Infectious; Squalene Monooxygenase; Terbinafine; Tinea; Trichophyton

An agar subcutaneous infection model (agar model), which simulates the rat subcutaneous infection model (rat model), was developed to assess the ability of antimicrobial catheters to resist microbial colonization. The catheters were implanted in the agar and rat models and the insertion sites were infected immediately or on day 7, 14 or 21 post-implantation. The catheters implanted in the agar model were transferred to fresh media one day before infection on day 7, 14 or 21. The efficacy of chlorhexidine and silver sulfadiazine impregnated (CS) catheters, CS catheters with higher levels of chlorhexidine (CS+ catheters), minocycline-rifampicin (MR) catheters and silver catheters against Staphylococcus aureus and rifampicin-resistant Staphylococcus epidermidis RIF-r2 was compared in the agar and rat models. No significant difference in the adherence or the drug release was found between the in vitro and in vivo models. In both models, CS+ and MR catheters were effective against S. aureus even when infected on day 14, whereas CS catheters were colonized when challenged on day 7. CS+ catheters were effective against S. epidermidis RIF-r2, whereas MR catheters showed adherence when infected on day 7. CS+ catheters prevented colonization of all the organisms including, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Candida albicans in the agar model, whereas MR catheters were effective only against S. aureus and S. epidermidis strains. Silver catheters were ineffective against all the organisms. The agar model may be used to predict the in vivo efficacy of antimicrobial catheters against various pathogens.

Topics: Agar; Animals; Anti-Bacterial Agents; Anti-Infective Agents, Local; Bacterial Adhesion; Bacterial Infections; Catheterization; Catheterization, Central Venous; Chlorhexidine; Culture Media; Disinfectants; Female; Rats; Rats, Sprague-Dawley; Silver Sulfadiazine; Skin Diseases, Infectious

Streptococcal surveys in foreign countries or remote areas may be greatly enhanced by the use of calcium alginate swabs desiccated in sterile silica gel. Delays of up to 4 weeks before return to a base laboratory are feasible, and the need for fresh media or laboratory facilities in the field may be eliminated. Comparison of direct plating on crystal violet blood agar versus delayed silica gel preservation during surveys in Uganda, Haiti, Colombia, and Miami, Fla., showed no significant loss of positive cultures from skin lesions and suggests that desiccated swabs increase the recovery of bacitracin-sensitive Streptococcus pyogenes (presumptive group A) from throats.

Topics: Agar; Animals; Bacitracin; Bacteriological Techniques; Blood; Child; Colombia; Drug Resistance, Microbial; Florida; Gels; Gentian Violet; Haiti; Humans; Infant; Methods; Pharynx; Sheep; Silicon Dioxide; Skin; Skin Diseases, Infectious; Specimen Handling; Streptococcus pyogenes; Tropical Climate; Uganda