Effects of topical agents for burns on Acinetobacter baumannii within biofilm / 中华烧伤杂志

<p><b>OBJECTIVE</b>To observe the antimicrobial activity of topical agents commonly used for burns on Acinetobacter baumannii (AB) in both free and biofilm states, and their synergistic effect with ambroxol on AB within biofilm.</p><p><b>METHODS</b>Eleven AB strains were isolated from wound excretion, respiratory tract, and blood of patients hospitalized in our hospital from August 2005 to April 2007. (1) The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of mafenide acetate and chlorhexidine acetate to free AB (including drug-resistant, drug-sensitive, and standard strains) were determined by dilution method. (2) AB was cultured with LB or TSB medium for 12, 24, and 48 h to form biofilm, and it was treated with above-mentioned two topical agents in MBC (mafenide group and chlorhexidine group) for 30 min. Biofilm not treated by topical agent was used as control group. The biofilm thickness was determined with confocal laser scanning microscope. The proportion of living bacteria in biofilm was calculated. AB biofilm in each topical agent group was mixed and inoculated into LB culture dish to observe the growth of bacteria. (3) AB was cultured with LB medium for 48 h to form biofilm, which was respectively treated by above-mentioned two topical agents in MBC (mafenide group and chlorhexidine group) and combination of each topical agent with 3.75 mg/mL ambroxol solution (ambroxol + mafenide group and ambroxol + chlorhexidine group) for 30 min. Biofilm not treated by topical agents was used as control group. Growth of bacteria in biofilm was detected with MTT method (denoted as absorbance value). Data were processed with one-way analysis of variance and LSD-t test.</p><p><b>RESULTS</b>(1) MIC of mafenide acetate and chlorhexidine acetate for free AB was respectively 25.00 mg/mL and 0.03 mg/mL. MBC of both agents for free AB was the same as their MIC. (2) Among three groups, the thickness of biofilm of sensitive AB was thicker than that of drug-resistant bacteria at most of the time points. Compared with those in control group, biofilm thickness and proportion of living bacteria in biofilm were slightly decreased in mafenide and chlorhexidine groups. The growth of bacteria was abundant in each group. (3) Absorbance value of drug-resistant bacteria in control, mafenide, and chlorhexidine groups was respectively 0.776 ± 0.071, 0.625 ± 0.063, and 0.420 ± 0.068. Absorbance value of drug-resistant bacteria in ambroxol + mafenide group (0.174 ± 0.089) was significantly lower than that of control group (t = 11.823, P = 0.000) and mafenide group (t = 9.248, P < 0.01). Absorbance value of ambroxol + chlorhexidine group (0.178 ± 0.044) was significantly lower than that of control group (t = 16.009, P = 0.000) and chlorhexidine group (t = 6.681, P < 0.01).</p><p><b>CONCLUSIONS</b>Drug-resistant AB forms biofilm readily, which prevents topical agents from killing the bacteria inside. Combined use of ambroxol with topical agents gives synergistic effect on killing AB in biofilm in the wound.</p>

Benign Papilloma Developed in Completely-healed Burn Wound

A 72-year-old female with 10% TBSA flame, mostly partial thickness, was treated topically with 10% mafenide acetate cream and 1% silver sulfadiazine cream. On day 28, burn wound was nearly healed but black colored, 3~5 mm sized maculopapular lesions developed in healed facial burn wound. Similar skin lesion progressed in both hand and both wrist. All skin lesions were peeled off. On day 30, biopsy was performed. An excisional biopsy of the lesion in the left cheek revealed benign papilloma. On day 44, we excised all skin lesions and performed STSG. All graft sites were healed 14th day after STSG.

Pseudomonas aeruginosa: burn infection, treatment and antibacterial resistance

Pseudomonas aeruginosa is an opportunistic pathogen causing severe, acute and chronic nosocomial infections in immunocompromised, catheterized or burn patients. Various types of virulent factors have been identified in P. aeruginosa, suggesting their contribution to the pathogenesis of the disease. The organism is generally resistant to numerous antimicrobial agents due to natural resistance in particular impermeability or mutations and acquisition of resistant determinants. Plasmid and integron have a crucial role in acquisition of mobile elements. Most treatment failures are related to inappropriate initial antibiotic therapy with insufficient coverage of multidrug resistant [MDR] pathogens, the rationale for using combinations of antibiotics to cover MDR gram-negatives. However, clinical data supporting this strategy are limited. In fact, systematic combination therapy may have contributed to the overuse of antibiotics and to the emergence of MDR microorganisms. Nevertheless, combination therapy is the best strategy to treat severe infections due to suspected MDR Pseudomonas. Optimally, therapeutic strategies should be sufficiently broad to cover relevant pathogens while minimizing the risk for emergence of antimicrobial resistance. Polymyxin E [colistin] and carbapenems are the most effective antibiotics against MDR isolates

Comparison of efficacy of honey versus silver sulfadiazine and acetate mafenid in the treatment of contaminated burn wounds in piggies

Introduction: Heat injury, with creation of conclusive necrosis in skin layers, prepares an environment suitable for bacterial infection as a result of low tissue perfusion and high protein content. Gram negative bacteries especially Pseudomonas Auroginosa have been recognized as the main creative organisms of wound infection mortality. Mankind has been interested in remedial role of honey since long.Materials and Sixty Indian piggies were categorized in three equal groups. A part of their body, approximately 8.5cm2, was burned with water steam [3 degree of burn]. Then, a number of 108 microorganisms of Pseudomonas Auroginosa were inoculated in the wound area. Each group was treated with group-specialized drug for a period of one month. [Honey- silver sulfadiazine 1%-acetat mafenid 8.5%]. In special days, according to determined schedule, animals' weight, as well as burn condition and extent were recorded and quantitative and qualitative cultural specimens were prepared periodically. The results were analyzed by statistical software of Spss10. Out of three groups, the group of honey had the mortality at least equal with two other groups[30% with comparison of 40% and 45%], the most formation of granulation tissue in a time of 10 days [90% with comparison of 35% and 44%], the smallest remaining wound at the end of study[percent of dwindle in size 62% in honey group with comparison of 29% and 22%] and the least of contamination in prepared specimens[20% in 10th day of burn with comparison of 95% and 100%]. Utilization of topical honey in treatment of deep and infectious burn in piggies not only accelerates the healing procedure but has antimicrobial effect at least equal to valuable acetate mafenid drug

Radiotratamiento de Mafenida 10 por ciento Crema / Radiotreatment with mafenide 10 per center cream

La aplicacion de las radiaciones ionizantes con fines descontaminantes constituye una alternativa para garantizar la calidad microbiologica de muchas producciones farmaceuticas. Se realizo el radiotratamiento de mafenida 10 por ciento crema que no cumplia con las especificaciones de calidad microbiologica establecidas en el pais. Para ello se determino la carga microbiana y se realizo un estudio de dosis en el producto, evaluandose 3,5,7 y 10 KGy de radiaciones gamma, con el empleo de una fuente radioisotopica de Co(60). Se realizaron evaluaciones microbiologicas y quimicofisicas pretratamiento y postratamiento y se definio irradiar el producto con 3 KGy como dosis minima, de forma continua y en la instalacion "Producto-I" del Instituto de Investigaciones para la Industria Alimenticia

Tratamiento tópico de las quemaduras

Hemos hecho un comentario de los principales antibacterianos de uso tópico para el tratamiento de las heridas por quemaduras, de acuerdo a la experiencia que hemos adquirido en los últimos dieciocho años, con el objeto de hacerlos conocer entre los profesionales médicos, que sin hacer la especialidad se ven en la necesidad de atender este tipo de pacientes en casos de emergencia. De los tres primeros que hemos señalado, la solución de Nitrato de Plata al 0.5 por ciento es la que más fácilmente está a nuestro alcance, pero como no se difunde en los tejidos, es considerada como preventivo ante las infecciones. El Mafanida (`Sulfamylon'), y la Silver-Diazina Argéntica (`Silvadene'), están indicados en caso de infecciones especialmente por Pseudomona Aeruginosa. En cuanto al Dermobrulen, preparado nacional que tiene com principio activo la candida krusei, su acción es muy precisa frente a lesiones de segundo grado no infectadas por formar una cubierta protectora en un promedio de tres días que impide la contaminación favoreciendo la epidermización en un período de tres a quince días