Diseño y evaluación de las propiedades antibacterianas de un prototipo de molde de audífono que incorpora cobre en su manufactura / Design and evaluation of antibacterial properties of a prototype of earmold with copper incorporated in the manufacture

Introducción: La otitis externa infecciosa es una consulta otorrinolaringológica frecuente en usuarios de audífonos. Las propiedades antibacterianas descritas del cobre, han motivado el desarrollo de aplicaciones clínicas de este metal. Objetivo: Evaluar la capacidad antibacteriana de moldes de audífonos manufacturados con polímeros sensible a luz UV, silicona y acrílico que incorporan cobre metálico, en un sistema experimental in vitro. Material y método: Se diseñaron moldes de audífonos con y sin cobre, que fueron inoculados con distintas concentraciones de microorganismos (S aureus y P aeruginosa), para luego determinar el porcentaje de adherencia bacteriana a distintos tiempos de contacto (4, 8 y12 horas). Resultados: Existió reducción significativa en la adhesión bacteriana a los moldes con cobre respecto a aquellos sin cobre, independiente del material, del tipo de microorganismo y del inóculo bacteriano. Discusión: La disminución en la adherencia bacteriana en los prototipos con cobre, puede atribuirse a su actividad inhibitoria sobre los microorganismos en función de su concentración y el tiempo de contacto, ejerciendo su efecto por difusión a través de los distintos materiales. Conclusión: Con estos resultados, se hace necesario el desarrollo de estudios clínicos enfocados en comprobar si el uso de audífonos con cobre disminuyen las otitis externas de origen infeccioso.

Introduction: External otitis of infectious etiology among hearing aid users is a common motive of otolaryngology consultation. Antibacterial properties described copper, they have motivated the development of clinical applications of this metal. Aim: Evaluate the antibacterial capacity of copper-based ear molds manufactured with different materials such UV sensitive polymers, silicone and acrylic incorporating metallic copper, in an experimental system in vitro. Material and method: Ear molds with and without copper, were inoculated with different concentrations of microorganisms (S aureus and P aeruginosa) and determine the percentage of bacterial adherence to different contact times (4-8 and 12 hours). Results: There was significant reduction in bacterial adhesion to copper molds than those without copper, independent of the material, the type of microorganism and the bacterial inoculum. Discussion: The decrease in bacterial adherence on prototypes with copper, can be attributed to inhibitory activity on microorganisms depending on their concentration and contact time, exerting its effect by diffusion through the various materials. Conclusion: With these results, is necessary the development of clinical studies focused on checking whether the use of hearing aids with copper decreases external otitis of infectious origin.

Actividad bactericida de superficies de cobre frente a bacterias asociadas a infecciones nosocomiales, en un modelo in vitro de adherencia y sobrevivencia / Adherence to copper and stainless steel metal coupons of common nosocomial bacterial strains

Background: Copper has a bactericidal activity against a series of bacterial strains. Aim: To measure resistance to bacterial adherence of copper (Cu) and stainless steel (SS) metal coupons. Material and Methods: Bacterial strains causing nosocomial infections in Chile were analyzed. Bacterial adherence was studied using apreviously described method based on a system of metal coupons that are immersed in culture media containing the bacteria ofinterest at room temperature. Results: Adherence to Cu and SS coupons was differentfor Methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae and Acinetobacter baumannii strains. For these strains, no adherence to Cu coupons occurred during the 48 h observation period compared to a rapidly increasing adherence to SS coupons, with a final colony count of 1.00E + 07 cfu/mL. For two different Pseudomonas aeruginosa clinical strains, inhibition of adherence was not observed on Cu coupons, and colony counts were similar for Cu and SS using the standard inoculum (2-3 xlO7 cfu).Apartial decrease in adherence was observed for Cu but not for SS coupons, when a lower inoculum was used. Conclusions: Copper surfaces represent an interesting option to reduce bacterial contamination in the hospital environment due to its resistance to bacterial adhesión ofmost ofthe common nosocomial bacterial strains.

Aplicación de la capacidad bactericida del cobre en la práctica médica / Application of copper bactericidal properties in medical practice

Background: Copper is essential for cell metabolism in animals and plants and thus for life. Along centuries, copper has been identified as a metal containing antimicrobial properties. In recent years, laboratory assays and clinical studies have revealed that surfaces of metallic copper or its alloys, containing at least 70% copper, eliminate in a few hours several pathogenic organisms including bacterial strains associated with nosocomial infections, influenza virus, HIV, and fungi such as Candida albicans. In March 2008, the American Environmental Protection Agency (EPA), supported by scientific evidence gathered to date, registered copper as the first and only metal with antimicrobial properties. We herein review certain mechanisms proposed for the antibacterial, antiviral and antifungal activity of copper. We also discuss in vitro and clinical efficacy studies developed world wide and in Chile, focusing on bactericidal activity of copper surface areas in comparison to materials typically used in hospital environments such as stainless steel and polymers. Scientific evidence gathered to date, consistently shows that the use of copper surface areas in high contact critical points in hospitals, significantly reduces environmental bacterial load. This is associated with a decreased risk of pathogen transmission to patients and represents therefore an interesting complement to infection control programs.

Síndrome hemolítico urémico asociado a infección intestinal por Escherichia coli productora de shigatoxina (STEC) en pacientes chilenos: aspectos clínicos y epidemiológicos / Hemolytic uremic syndrome associated to shigatoxin producing Escherichia coli in Chilean children: clinical and epidemiological aspects

Clinical and epidemiological aspects of shigatoxin producing E. coli (STEC) infections and hemolytic uremic syndrome (HUS) are reviewed. Surveillance results from 14 sentinel centers during 2000-2002 showed a mean incidence rate of 3.4 HUS cases per 100.000 children, with the highest incidence in the 6 to 28 month age group. Disease is endemic with summer peaks. Between 1988 and 2002 we obtained the clinical characteristics of a group of 119 HUS children with the following results: mean age 16 months, bloody diarrhea 57.8 percent, no previous diarrhea 9 percent, 60 percent received antibiotics, 72 percent had oligoanuria, 53 percent required dialysis, 15 percent had seizures and 31 percent had dizziness; mortality was 3 percent. Four foodborne outbreaks have been detected in Santiago, two outbreaks occurred in household settings, one in a Day Care Center and one in a Neonatal Unit. Recommendations for diagnosis, treatment and prevention of STEC infections, including potential vaccines are discussed.

Se revisan y actualizan aspectos clínicos y epidemiológicos de las infecciones por Escherichia coli productora de shigatoxina (STEC), y el síndrome hemolítico urémico (SHU). Se incluyen resultados de una vigilancia de SHU en 14 centros centinelas (2000-2002), que mostró una incidencia promedio de 3,4 casos por 100.000 niños, 78 por ciento) en el grupo de 6 a 48 meses. Esta vigilancia reflejó una situación endémica, con aumento en verano. Se analiza la observación clínica protocolizada de 119 pacientes con SHU hospitalizados en la Región Metropolitana (RM) (1988 y 2002). Edad promedio: 16 meses. El 578 por ciento> tenía diarrea con sangre, 9 por ciento> no tenía diarrea previa, 60 por ciento> recibió antibacterianos, 72 por ciento> presentó oligoanuria y 53 por ciento> necesitó diálisis. El 31 por cientoo tuvo compromiso de conciencia y 15 por cientoo presentó convulsiones. Letalidad 3 por ciento. Se analizan brotes de STEC asociados a alimentos ocurridos en la RM en el hogar (2), un jardín infantil (1) y en un servicio de neonatología (1). Finalmente, se entregar recomendaciones para el manejo clínico y prevención, se revisan los criterios diagnósticos, nuevas estrategias terapéuticas y progresos en el desarrollo de vacunas.

Actividad comparativa in vitro de cefpodoxima en relación a otros antibióticos de uso frecuente, frente a patógenos respiratorios, urinarios y de infecciones de partes blandas / Activity of cefpodoxime against pathogens causing respiratory, urinary or soft tissue infections

Background: Cefpodoxime is a new antimicrobial in the Chilean market, recommended for treatment of respiratory and urinary tract infections. Aim: To study the susceptibility of common pathogens isolated from Chilean patients to cefpodoxime and other antimicrobials. Material and methods: The in vitro activity of cefpodoxime, expressed as Minimal Inhibitory Concentration, was studied in 331 S pneumoniae, H influenzae, M catarrhalis, E coli, S aureus and S pyogenes strains, isolated between 2000 and 2004 from respiratory, urinary and soft tissue infections, respectively. Results: Eleven percent of S pneumoniae isolates were resistant to penicillin, 11% were resistant to cefuroxime and 10% to cefpodoxime. All H influenzae isolates were susceptible to cefpodoxime. No H influenzae isolates were resistant to second or third generation cephalosporines. Four percent of H influenzae isolates were resistant to ampicillin by ß-lactamase production. In contrast 81% of M catarrhalis strains were resistant to ampicillin. Six percent of E coli isolates were resistant to cefpodoxime, 9% to cefuroxime, 11% to cefadroxile and 50% to ampicillin or trimethoprim/sulphamethoxazole. Cefpodoxime was the most active antimicrobial against S pyogenes. Conclusions: Cefpodoxime, recently introduced in Chile, is a good alternative for the treatment of common respiratory and urinary tract infections.

Perfil de susceptibilidad a los antimicrobianos en cepas de E coli productoras de Shiga toxina (STEC) aisladas de infecciones humanas y de alimentos / Antimicrobial susceptibility of shiga toxin producing E coli (STEC) strains isolated from human infections and food

BACKGROUND: Shiga toxin-producing E coli (STEC) are zoonotic pathogens associated to sporadic episodes of bloody diarrhea, foodborne outbreaks, and Hemolytic Uremic Syndrome (HUS), with worldwide public health impact. Antibiotic use in STEC infections is controversial because of the potential to increase production and secretion of Shiga toxins. AIM: To study the in vitro antimicrobial susceptibility profile of STEC. MATERIAL AND METHODS: The in vitro susceptibility profile against 10 antimicrobials of STEC strains isolated from 29 meat products, 20 patients with diarrhea and 9 HUS patients was studied. Minimal Inhibitory Concentrations (microg/ml) by agar dilution method for ampicillin, cloramphenicol, ciprofloxacin, amikacin, gentamycin, cotrimoxazol, ceftriaxone, tetracycline, fonsfomycin and azihromycin were measured according to NCCLS recommendations. RESULTS: Strains from patients with diarrhea or HUS were all susceptible to the 10 antimicrobials and only 13.7% had intermediate resistance to cloramphenicol. Strains from meat products had a similar susceptibility profile, with only 3.5% resistance to tetracycline, 3.5% intermediate resistance to cloramphenicol and 7% to fosfomycin. All 58 strains were considered resistant to azithromycin (MIC >32 microg/ml). CONCLUSIONS: Similarity of susceptibility profiles between STEC strains from human and food origin suggests a role of food chain in transmission to humans.

Evaluación pre-analítica de dos métodos de extracción de ADN para la amplificación del gen de la pneumolisina (PLY) de Streptococcus pneumoniae, en muestras de hemocultivo / Assessment of two DNA extraction methods to amplify the pneumolysin gene (PLY) from blood culture samples of Streptococcus pneumoniae

Background: Streptococcus pneumoniae is a common etiologic agent of invasive respiratory infections among children under 5 years of age and older adults. Isolation rates of S. pneumoniae by traditional culture techniques are low. Aim: To study the sensitivity and specificity of two different DNA extraction methods to amplify the ply gene, applied to three different types of blood culture broths, experimentally inoculated with S. pneumoniae. Material and methods: DNA was extracted from the cultures using an organic method or a technique that consists in dilution, washing with NaOH and concentration of the sample. This was followed by PCR amplification of a 355 pb fragment of the pneumolysin gene (ply). Results: The organic DNA extraction method inhibited the PCR reaction at all concetrations studied (0.6 to 10(6) colony forming units/mL). Using the NaOH extraction, ply gene amplification was positive in all three blood culture broths, but only at concentrations of 10 colony forming units/mL or higher. Using the same DNA extraction method, PCR was negative when the broths were inoculated with seven other related bacterial species, which results in a 100 percent specificity. Conclusions: Detection of S. pneumoniae by amplification of ply gene from blood cultures using the protocol of NaOH for DNA extraction is specific and provides results in a short lapse. However, the diagnostic sensitivity is not optimal, wich limits its clinical use.

Serotipos y susceptibilidad antimicrobiana de Streptococcus agalactiae / Serotypes and antimicrobial susceptibility of Streptococcus agalactiae

Background : Streptococcus agalactiae or group B streptococcus, GBS, is the leading cause of neonatal and maternal infections and an opportunistic pathogen in adults with underlying disease. In the last decade, a dramatic increase in the resistance of this microorganism to erythromycin and clindamycin has been observed. Aim: To determine the serotype distribution and antimicrobial susceptibility of isolates of S agalactiae collected from infections and colonization and to assess the genetic mechanisms of macrolide and clindamycin resistance. Material and methods: A total of 100 GBS isolates were collected between 1998 and 2002, in Santiago, Chile. They were isolated from the amniotic fluid from patients with premature rupture of membranes (7 isolates), blood from neonatal sepsis (10 isolates), neonate colonizations (2 strains), skin and soft tissue infections (7 isolates), urinary tract infections (5 isolates), genital infections (3 isolates), articular fluid (one isolate), and 65 strains were recovered from vaginal colonization55. Results: Serotypes Ia, II and III were the predominant serotypes identified in our study, accounting for 90 (90 percent) of the strains. Five isolates belonged to serotypes Ib (5 percent) and two (2 percent) to serotype V respectively; no strains belonging to serotype IV were found. All strains were susceptible to penicillin G, ampicillin and cefotaxime, and four isolates (4 percent) were resistant to both erythromycin (MIC >64 µg/ml) and clindamycin (MIC >64 µg/ml). The strains had a constitutive macrolide-lincosamide-streptogramin (cMLSB) resistance phenotype and the erm(A) gene was present in the four isolates. Conclusions: Serotypes Ia, II and III were the predominant serotypes in this study. All strains were susceptible to penicillin G, ampicillin and cefotaxime, and four (4 percent) strains were resistant to both erythromycin and clindamycin. The cMLSB resistance phenotype, and the erm(A) gene was detected in resistant strains (Rev MÚd Chile 2004; 132: 549-55).

Red de vigilancia de resistencia antimicrobiana PRONARES: informe primer semestre 2001 / PRONARES antimicrobial surveillance network on antimicrobial agents resistance: report of the first semester 2001

En el transcurso de los años hemos sido testigos de un creciente problema de resistencia antimicrobiana, fenómeno que involucra cada día mayor número de cepas, nuevas especies y nuevos mecanismos. En noviembre de 1997 iniciamos una red de vigilancia de resistencia antimicrobiana PRONARES (Programa Nacional de Resistencia), en diferentes hospitales del país, que trabajando un protocolo común (20 cepas por síndrome clínico por mes) y utilizando un programa computacional WHONET (diseñado para vigilancia), nos permitiera detectar y monitorear el problema de la resistencia bacteriana en Chile. Los resultados del primer semestre de este año reportan 5.251 cepas de diferentes síndromes clínicos. En ITU, Escherichia coli (1.088 cepas) demostró alta susceptibilidad a todos los antimicrobianos, Klebsiella (1.000 cepas) demostró un perfil de resistencia más elevado, en cepas de Enterococcus spp se observó 30 por ciento de resistencia a ciprofloxacina y 2 por ciento a nitrofurantoína. Entre 899 cepas procedentes de infecciones invasoras, Staphylococcus aureus (555 cepas), mostró elevado perfil de resistencia a cloxacilina 40 por ciento superior -40 por ciento (21 por ciento) al observado en cepas aisladas de piel y tejido blandos (550). Shigella spp, (137 cepas) presentó 80 por ciento de resistencia ampicilina y 32 por ciento a cloranfenicol; ciprofloxacina y furazolidona demostraron muy buena actividad in vitro frente a este enteropatógeno. Al comparar cepas nosocomiales y de la comunidad, las primeras mostraron un perfil de mayor resistencia. Mantener una red nacional de vigilancia de resistencia se hace cada vez más necesario para orientar el uso adecuado de antibacterianos y evitar así que el fenómeno aumente

Perfil de resistencia a los antimicrobianos en agentes causantes de infección del tracto urinario en niños chilenos: programa de vigilancia PRONARES / Antimicrobial susceptibility of agents causing urinary tract infections in chilean children: PRONARES surveillance program

Background: PRONARES (Programa Nacional de Vigilancia de Resistencia) is a national surveillance program for antimicrobial susceptibility, focused in different syndromes and among these, urinary tract infections. The work is done in a laboratory net that uses common protocols and whose data are centrally analyzed using the WHONET program. Aim: To analyze the pattern of antimicrobial susceptibility of agents causing urinary infections in children in the period 1997-1999. Material and methods: In the study period, 5,525 strains were analyzed. Of these, 2,307 came from pediatric patients (1,495 hospitalized and 803 ambulatory). Results: The most common causative agent was E. coli in 74,2 percent of cases, followed by Klebsiella spp in 8,2 percent and other agents in a lower frequency. Of E. coli strains, 74 percent were resistant to ampicillin, 52 percent to clotrimoxazole and 30 percent to first generation cephalosporins. These strains were sensitive to second and third generation cephalosporins, aminoglycosides, ciprofloxacin and nitrofurantoin. Strains from nosocomial or community infections had similar antimicrobial susceptibility. Klebsiella spp had a high rate of antimicrobial resistance (over 40 percent), that was even higher among nosocomial strains. It was 90 percent susceptible to ciprofloxacin and 100 percent to imipenem. All centers from which strains came had a similar pattern of susceptibility, with the exception of a pediatric center that had significantly higher resistance levels. Conclusions: The current therapeutic recommendations for urinary tract infections in children caused by E coli, are still pertinent, but the use of first generation cephalosporins must be cautious. The treatment of Klebsiella spp requires an individual antibiogram

Actividad comparativa in vitro de moxifloxacina y otros antimicrobianos frente a patógenos respiratorios / Comparative in vitro activity of moxifloxacin and other antimicrobials against respiratory pathogens

Background: Respiratory pathogens are becoming increasingly resistant to antimicrobials. A new group of drugs, called respiratory quinolones have been synthesized to overcome this problem. Aim: To study the in vitro susceptibility of respiratory pathogens to old and new antimicrobials. Material and methods: Forty five strains of S pneumoniae, 44 strains of H influenzae, 21 strains of M catarrhalis, 10 strains of methicillin susceptible S aureus and 20 strains of methicillin resistant S aureus were studied. All were isolated from community acquired respiratory infections during 1999. Minimal inhibitory concentrations of moxifloxacin, amoxicilin, amoxicilin/clavulanic acid, clarithromycin, azithromycin, ciprofloxacin and levofloxacin were determined using the Etest method. Betalactamase production by H influenzae and M catarrhalis was also studied. Results: S pneumoniae strains were 100 percent susceptible to quinolones and cotrimoxazole, 2 percent were resistant to macrolides, 11 percent were resistant to amoxicilin/clavulanic acid and 47 percent were resistant to cefuroxime. H influenzae was 100 percent susceptible to quinolones, azithromycin and amoxicilin/clavulanic acid. There was a 53 percent resistance to cotrimoxazole, 21 percent to amoxicilin, 9 percent to clarithromycin and 7 percent to cefuroxime. M catarrhalis was 100 percent susceptible to quinolones and 100 percent resistant to amoxicilin, 5 percent resistant to macrolides, 14 percent resistant to amoxicilin/clavulanic acid, 20 percent to cefuroxime and 30 percent to cotrimoxazole. Methicilline susceptible S aureus was susceptible to all antimicrobials and methicillin resistant S aureus was resistant to all. Conclusions: Moxifloxacin and the new respiratory quinolones can be useful in the treatment of respiratory infections