Naranja de acridina para el diagnóstico de bacteriemias relacionadas con catéteres / Acridine orange staining method in the diagnosis of catheter-related bloodstream infections

Objetivo. Estudiar la utilidad de la tinción con naranja de acridina (NDA) de la sangre extraída a través del dispositivo intravenoso (DI) para el diagnóstico de bacteriemia relacionada con catéter (BRC). Diseño. Se trata de un estudio prospectivo y observacional. Pacientes. Se incluyeron pacientes con DI centrales que presentaron clínica compatible con BRC y aceptaron participar. Se excluyeron todos aquéllos con confirmación de otro foco infeccioso. Intervención. Ante la sospecha clínica de BRC y antes de retirar el DI, se extraían muestras de sangre periférica y a través del DI para analizarlas con la técnica de la tinción con NDA. El DI se retiraba y era enviado para su análisis mediante las técnicas de Liñares et al y Maki et al. Se consideró BRC el crecimiento del mismo microorganismo en sangre periférica y en el extremo del catéter (luz 103 UFC/ml y/o superficie 15 UFC/ml). Variables de interés. Se calculó la sensibilidad, la especificidad, los valores predictivos y los cocientes de probabilidades de la prueba de NDA para el diagnóstico de BRC. Resultados. Se estudiaron 121 pacientes y se diagnosticaron 4 BRC: 2 por Staphylococcus aureus, 1 por Pseudomonas aeruginosa y 1 por Candida albicans. La sensibilidad de la tinción con NDA fue del 87,5%, la especificidad del 92,7%, el valor predictivo negativo del 99,5%, el cociente de probabilidades positivo 12,04 y el cociente de probabilidades negativo 0,13. Conclusiones. Si bien el bajo número de eventos no permite estimar la eficacia de la tinción con NDA para el diagnóstico de BRC, su alto valor predictivo negativo permitiría descartar con cierta seguridad esta complicación infecciosa (AU)

Objective. To study if the utility of acridine orange (AO) staining method on blood extracted through intravenous device (ID) is a reliable method to diagnose catheter-related bloodstream infection (CRB). Design. Prospective and observational study. Patients. Patients with central ID and clinical data consistent with CRB who gave their consent to participate. Patients having another infection site were excluded. Intervention. At the moment of the clinical suspicion of CRB and before removing the ID, blood samples were extracted from peripheral veins and through the ID to be analyzed by AO staining. After extracting the samples, the catheter was removed and sent for microbiological analysis with Liñares et al and Maki et al techniques. CRS was defined as development of the same microorganism in the tip of the catheter (endoluminal surface with 103 UFC/ml and/or extraluminal surface 15 UFC/ml) and in the peripheral blood. Variables of interest. Sensitivity, specificity, negative and positive and negative predictive val- ues and positive likelihood ratios (LR) were calculated for the diagnosis of CRB. Results. A total of 121 patients were studied and 4 were diagnosed with CRB: 2 infected with Staphylococcus aureus, 1 with Pseudomonas aeruginosa and 1 with Candida albicans. AO sensitivity was 87.5%, specificity 92.7% and the negative predictive value was 99.5%. Positive likelihood ratio was 12.04 and negative LR 0.13. Conclusions. Although the number of events does not allow for the estimation of the efficacy of AO to diagnose CRB, its high negative predictive value would make it possible to rule out this infectious complication with some degree of safety (AU)

[Acridine orange staining method in the diagnosis of catheter-related bloodstream infections]. / Naranja de acridina para el diagnósticode bacteriemias relacionadas con catéteres.

OBJECTIVE: To study if the utility of acridine orange (AO) staining method on blood extracted through intravenous device (ID) is a reliable method to diagnose catheter-related bloodstream infection (CRB). DESIGN: Prospective and observational study. PATIENTS: Patients with central ID and clinical data consistent with CRB who gave their consent to participate. Patients having another infection site were excluded. INTERVENTION: At the moment of the clinical suspicion of CRB and before removing the ID, blood samples were extracted from peripheral veins and through the ID to be analyzed by AO staining. After extracting the samples, the catheter was removed and sent for microbiological analysis with Liñares et al and Maki et al techniques. CRS was defined as development of the same microorganism in the tip of the catheter (endoluminal surface with > or = 10 (3) UFC/ml and/or extraluminal surface > or = 15 UFC/ml) and in the peripheral blood. VARIABLES OF INTEREST: Sensitivity, specificity, negative and positive and negative predictive values and positive likelihood ratios (LR) were calculated for the diagnosis of CRB. RESULTS: A total of 121 patients were studied and 4 were diagnosed with CRB: 2 infected with Staphylococcus aureus, 1 with Pseudomonas aeruginosa and 1 with Candida albicans. AO sensitivity was 87.5%, specificity 92.7% and the negative predictive value was 99.5%. Positive likelihood ratio was 12.04 and negative LR 0.13. CONCLUSIONS: Although the number of events does not allow for the estimation of the efficacy of AO to diagnose CRB, its high negative predictive value would make it possible to rule out this infectious complication with some degree of safety.

[Distribution of capsular types and antimicrobial susceptibility of Streptococcus agalactiae causing infections in Argentina]. / Distribución de tipo capsular y sensibilidad antimicrobiana de Streptococcus agalactiae productores de infecciones en Argentina.

Streptococcus agalactiae is an endogenous bacterium that has emerged in the last 20 years as an etiological agent in both neonatal and perinatal infections, and in immunocompromised patients. The differentiation of the capsular polysaccharide, the presence of surface proteins c, X, R, and molecular methods allow classification in serotypes and genotypes. This identification is a useful tool for epidemiological purposes and virulence studies in this bacterium. The objective of this work was to study the serotypes and the antimicrobial susceptibility of isolates recovered from invasive diseases in different areas of Argentina. In the analyzed sample a fair predominance of Ia and III serotypes was recovered, followed by II and IV serotypes. All the isolates were found to be sensitive to penicillin. A 6% of resistance to erythromycin and a 4.5% to clindamycin were detected. In three of the isolates, constitutive MLS phenotype (resistance to macrolides, lincosamins and streptogramins) was founded, while in the remaining one, inducible MLS phenotype was detected. These results stress the importance of conducting a surveillance of the prevalent serotypes in our country with the goal of future prevention of this disease with an effective vaccine. The knowledge of the antimicrobial susceptibility profile will be also important to obtain therapeutic success in the treatment.

Distribución de tipo capsular y sensibilidad antimicrobiana de Streptococcusagalactiae productores de infecciones en Argentina / Distribution of capsular types and antimicrobial susceptibility of Streptococcus agalactiae causing infections in Argentina

Streptococcus agalactiae es una bacteria colonizante que ha emergido en los últimos años como causante de infecciones neonatales, perinatales y en pacientes con compromiso inmunológico. La caracterización del polisacárido capsular, de las proteínas de superficie (c, X, R), así como el análisis de marcadores moleculares, permiten su clasificación en serotipos y genotipos. Esto resulta de utilidad para fines epidemiológicos y para estudios de virulencia de la bacteria. El objetivo de este trabajo fue conocer los serotipos prevalentes y la sensibilidad antimicrobiana de aislamientos provenientes de procesos infecciosos en pacientes de distintas zonas de Argentina. En la muestra analizada se obtuvo predominio de los serotipos Ia y III, seguido de II y IV. Todas las cepas resultaron sensibles a penicilina. Se observó 6% de resistencia a eritromicina y 4,5% a clindamicina. En 3 de las cepas se detectó fenotipo MLS (resistencia a macrólidos, lincosaminas y estreptograminas) constitutiva y en una cepa, resistencia MLS inducible. Los resultados logrados en este estudio destacan la importancia de efectuar un relevamiento de los serotipos más frecuentes en nuestro país en vistas a la prevención de esta infección con una vacuna que realmente sea eficaz, como así también el conocimiento de la sensibilidad antimicrobiana para lograr éxito terapéutico en los tratamientos.

Streptococcus agalactiae is an endogenous bacterium that has emerged in the last 20 years as an etiological agent in both neonatal and perinatal infections, and in immunocompromised patients. The differentiation of the capsular polysaccharide, the presence of surface proteins c, X, R, and molecular methods allow classification in serotypes and genotypes. This identification is a useful tool for epidemiological purposes and virulence studies in this bacterium. The objective of this work was to study the serotypes and the antimicrobial susceptibility of isolates recovered from invasive diseases in different areas of Argentina. In the analyzed sample a fair predominance of Ia and III serotypes was recovered, followed by II and IV serotypes. All the isolates were found to be sensitive to penicillin. A 6% of resistance to erythromycin and a 4.5% to clindamycin were detected. In three of the isolates, constitutive MLS phenotype (resistance to macrolides, lincosamins and streptogramins) was founded, while in the remaining one, inducible MLS phenotype was detected. These results stress the importance of conducting a surveillance of the prevalent serotypes in our country with the goal of future prevention of this disease with an effective vaccine. The knowledge of the antimicrobial susceptibility profile will be also important to obtain therapeutic success in the treatment.

Distribución de tipo capsular y sensibilidad antimicrobiana de Streptococcus agalactiae productores de infecciones en Argentina. / [Distribution of capsular types and antimicrobial susceptibility of Streptococcus agalactiae causing infections in Argentina]

Streptococcus agalactiae is an endogenous bacterium that has emerged in the last 20 years as an etiological agent in both neonatal and perinatal infections, and in immunocompromised patients. The differentiation of the capsular polysaccharide, the presence of surface proteins c, X, R, and molecular methods allow classification in serotypes and genotypes. This identification is a useful tool for epidemiological purposes and virulence studies in this bacterium. The objective of this work was to study the serotypes and the antimicrobial susceptibility of isolates recovered from invasive diseases in different areas of Argentina. In the analyzed sample a fair predominance of Ia and III serotypes was recovered, followed by II and IV serotypes. All the isolates were found to be sensitive to penicillin. A 6

of resistance to erythromycin and a 4.5

to clindamycin were detected. In three of the isolates, constitutive MLS phenotype (resistance to macrolides, lincosamins and streptogramins) was founded, while in the remaining one, inducible MLS phenotype was detected. These results stress the importance of conducting a surveillance of the prevalent serotypes in our country with the goal of future prevention of this disease with an effective vaccine. The knowledge of the antimicrobial susceptibility profile will be also important to obtain therapeutic success in the treatment.