S. pneumoniae is a significant cause of community-acquired pneumonia in the elderly, and accounts for the majority of the pneumonia deaths among the elderly. We conducted this randomized double-blind study to evaluate the immune response to a 23-valent pneumococcal polysaccharide vaccine and the persistence of antibodies two years after the vaccination in an elderly population in Santiago, Chile. A total of 118 elderly nursing home residents received either the pneumococcal or a tetanus control vaccine. Serum samples were taken at enrolment, at two months, and at two years post-vaccination. Pre-vaccination anti-pneumococcal antibody geometric mean concentrations (GMC) were similar in both study groups, with increased levels of antibodies found only against serotype 14. The pneumococcal vaccine was highly immunogenic at 2 months, and titers remained high two years after the vaccination for the 10 serotypes studied in this elderly population. The results thus support the benefits of this pneumococcal vaccine in this elderly population who are at increased risk of invasive pneumococcal disease.

Background: S pneumoniae is the main cause of community-acquired pneumonia in the elderly, group that concentrates 95% of deaths. Aim: To assess the prevalence of nasal carriage of S pneumoniae in institutionalized elderly patients. Material and methods: One hundred eighteen institutionalized subjects aged over 60 years (65 males) were enrolled. Since they were also participating in a controlled protocol related to the immunogenicity of an anti-pneumococcal vaccine, our investigation was also blind and randomized. According to randomization, they received pneumococcal or tetanic vaccine. Nasal swab cultures were taken at the beginning of the trial and two months after vaccination. According to recommended methods, we identified S pneumoniae, the serotypes and their antimicrobial susceptibility. Results: In the first nasal sample, 16% of subjects were positive for S pneumoniae. The second sample was positive in 12%. Of the 33 isolated serotypes, 9.1% demonstrated intermediate resistance to penicillin and 3.3% were resistant to chloramphenicol. Conclusions: The study demonstrated a greater percentage of colonized patients than in the general population. The isolated serotypes are the same that cause invasive diseases in this age group, according to data of the Institute of Public Health of Chile. There were no differences in the percentage of colonization between subjects vaccinated against S pneumoniae and control groups, after two months of follow up. Isolated strains had a low resistance to penicillin. High level resistance was not observed

The Chilean Public Health Institute and the Chilean Infectious Diseases Society have joined efforts to coordinate and co-manage a national surveillance network for bacterial antimicrobial resistance by clinical syndromes. The aim of this network is to establish a national surveillance system of antimicrobial bacterial resistance, standardized and coordinated, to obtain current information about the most relevant pathogens by well defined clinical syndromes, age of patients and origin of strains: community or nosocomial acquired infection. The participation of all National Public Health Divisions is considered of great importance, to obtain solid data, representative of the whole national epidemiological situation, in order to offer the best treatment to our patients.

El Instituto de Salud Pública de Chile y la Sociedad Chilena de Infectología han aunado sus esfuerzos para coordinar y co-dirigir una red nacional para la vigilancia de resistencia de agentes patógenos a antimicrobianos según síndromes clínicos. El objetivo de esta red es establecer un sistema nacional de vigilancia de la resistencia a antimicrobianos, estandarizado y coordinado, que proporcione información actualizada acerca de los agentes infecciosos más relevantes por síndromes clínicos bien definidos, por edad y por lugar de origen: hospitalaria o de la comunidad. Nos parece fundamental la participación de todos los Servicios de Salud del país en esta red, para obtener datos de calidad, representativos de nuestra realidad nacional, que sean de real utilidad en el manejo de los pacientes.

During the last years we have seen are emerging antimicrobial agents resistance that compromise more strains, new species and new mechanisms. In November 1997 we iniciated a network of antimicrobial surveillance named PRONARES in differents hospitals that working with a unique protocol (20 strains by month by syndrome) and using a computational software WHONET surveys the resistance in Chile. The results obtained during the first semester of 2001 shows the susceptibility pattern of 5.251 strains isolated from different clinical syndromes. In urinary tract infections E. coli (1.088 strains) were very susceptible to all the antibiotics tested, Klebsiella spp (1.000 strains) were more resistant. In Enterococcus we observed 30% of ciprofloxacin resistance and 2% of nitrofurantoin resistance. Among 899 invasive strains, S. aureus (655 strains) presented a high methicillin resistance level (40%) more than 20% observed in skin and soft tissue infections. Shigella spp (137) presented 80% of ampicillin resistance and 32% to chloramphenicol. Ciprofloxacin and furazolidone had better activity. Comparing nosocomial and community strains, the higher pattern of resistance was observed in nosocomial strains. It is very important to maintain the surveillance network to prescribe the appropriate antimicrobial and to avoid the increase of resistance

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% de resistencia a ciprofloxacina y 2% a nitrofurantoína. Entre 899 cepas procedentes de infecciones invasoras, Staphylococcus aureus (555 cepas), mostró elevado perfil de resistencia a cloxacilina 40% superior -40%- (21%) al observado en cepas aisladas de piel y tejidos blandos (550). Shigella spp, (137 cepas) presentó 80% de resistencia a ampicilina y 32% 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

The genus Haemophilus comprises a group of small, pleomorphic gram negative rods with fastidious growth requirements. H. influenzae type b the most important, is a small gram negative coccobacillus that appears pleomorphic in clinical smears. It is a non motile bacteria, non spore-forming, facultative anaerobe, that requires two accessory factors (X-V) for in vitro growth. Both factors are present within erythrocytes and are released by heat (chocolate agar). The main criterium for diagnosis of H. influenzae infections is Gram stain and isolation of the organisms from the infected focus. Because H. influenzae is very fastidious and dies quickly in clinical specimens at room temperature, samples should be planted immediately. They should be streaked directly on the surface of a chocolate agar and incubated aerobically in an atmosphere of 10% CO2. The treatment of invasive H. influenzae, infections specially meningitis, is a medical emergency, any unnecessary delay in starting treatment may make the difference between life and death, so the knowledge of antimicrobial susceptibility pattern is a clue that helps in the empiric treatment. Locally antimicrobial susceptibility rutine study (Kirby Bauer for non invasive strains and E-test for invasive strains) must be performed in HTM medium

El género Haemophilus comprende un grupo de bacilos Gram negativos de requerimientos fastidiosos. H. influenzae tipo b, la especie más importante, es un cocobacilo Gram negativo pequeño, que en muestras clínicas aparece pleomórfico. Es una bacteria inmóvil, no esporulada, anaerobia facultativa, que requiere dos factores de crecimiento (X-V) presentes en eritrocitos, los cuales son liberados mediante calor (agar chocolate). El principal criterio diagnóstico para las infecciones por H. influenzae es la tinción de Gram y el aislamiento del microorganismo del sitio de infección. Por ser el Haemophilus muy fastidioso, las muestras deben ser sembradas inmediatamente, en la superficie de un agar chocolate e incubadas en ambiente de 10% de Co2. El tratamiento de las infecciones invasoras por Haemophilus tipo b, especialmente meningitis, es una emergencia médica, cualquier retardo en el inicio del tratamiento puede hacer diferencia entre la vida y la muerte, por tanto el conocimiento del patrón de susceptibilidad antimicrobiana de las cepas es clave para ayudar el tratamiento empírico. El estudio de susceptibilidad antimicrobiana de rutina realizado localmente (Kirby Bauer en caso de cepas no invasivas y E-test en invasivas) debe ser realizado en HTM medium

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% of cases, followed by Klebsiella spp in 8,2% and other agents in a lower frequency. Of E. coli strains, 74% were resistant to ampicillin, 52% to clotrimoxazole and 30% 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%), that was even higher among nosocomial strains. It was 90% susceptible to ciprofloxacin and 100% 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 (Rev Méd Chile 2001; 129: 877-885).

Background: The computer program WHONET generates a common database to analyze local or general antimicrobial resistance of bacteria. A surveillance of agents causing urinary tract infections in Chile has been performed using this program. Aim: To report the results after 12 months of urinary tract infection agent surveillance. Material and methods: Since November, 1997, a surveillance of in vitro antimicrobial resistance, using agar diffusion techniques, has been performed in 20 to 40 bacterial strains per month, isolated from 11 hospitals in the country. Results have been analyzed using WHONET program. Results: In first 12 months, 3144 strains, 1625 coming from outpatients, have been studied. Seventy four percent of isolated strains were E coli, 19% were other enterobacteria, 4.1% were non fermenting bacilli and 2.1% were Gram (+) cocci. Sixty five percent of E coli strains were resistant to ampicillin, 11% to cefazolin, 2.5% to cefuroxime, 19% to ceftriaxone, 9% to ceftazidime, 4.2% to gentamicin 1.3% to amikacin, 5.6% to ciprofloxacin, 8.4% to grepafloxacin, 4.3% to nitrofurantoin and 43% to trimeproprim/sulphamethoxazole. Eighty two percent of other enterobacteria strains were resistant to ampicillin, 45.5% to cefazolin, 33.5% to cefuroxime, 26.6% to ceftriaxone, 21.5% to ceftazidime, 30.3% to gentamicin 17.2% to amikacin, 21% to ciprofloxacin, 16.3% to grepafloxacin, 48.2% to nitrofurantoin and 44.6% to trimeproprim/sulphamethoxazole. There were differences in betalactamic resistance among hospitals. Conclusions: Noteworthy is the high resistance rates to third generation cephalosporins, evidenced when the new cutoff values for E coli and Klebsiella spp are used. This national surveillance provides updated information on antimicrobial resistance of agents causing urinary tract infections.