Comparison of two MALDI-TOF MS systems for the identification of clinically relevant anaerobic bacteria in Argentina.

The aim of this study was to compare the performance of two MALDI-TOF MS systems in the identification of clinically relevant strict anaerobic bacteria. The 16S rRNA gene sequencing was the gold standard method when discrepancies or inconsistencies were observed between platforms. A total of 333 isolates were recovered from clinical samples of different centers in Buenos Aires City between 2016 and 2021. The isolates were identified in duplicate using two MALDI-TOF MS systems, BD Bruker Biotyper (Bruker Daltonics, Bremen, Germany) and Vitek MS (bioMèrieux, Marcy-l'Etoile, France). Using the Vitek MS system, the identification of anaerobic isolates yielded the following percentages: 65.5% (n: 218) at the species or species-complex level, 71.2% (n: 237) at the genus level, 29.4% (n: 98) with no identification and 5.1% (n: 17) with misidentification. Using the Bruker Biotyper system, the identification rates were as follows: 85.3% (n: 284) at the species or species-complex level, 89.7% (n: 299) at the genus level, 14.1% (n: 47) with no identification and 0.6% (n: 2) with misidentification. Differences in the performance of both methods were statistically significant (p-values <0.0001). In conclusion, MALDI-TOF MS systems speed up microbial identification and are particularly effective for slow-growing microorganisms, such as anaerobic bacteria, which are difficult to identify by traditional methods. In this study, the Bruker system showed greater accuracy than the Vitek system. In order to be truly effective, it is essential to update the databases of both systems by increasing the number of each main spectrum profile within the platforms.

Utilidad del panel FilmArray® BCID en la detección de bacteriemia: estudio multicéntrico latinoamericano / Usefulness of the FilmArray® BCID panel in the detection of bacteremia: Latin American multicenter study

Resumen Los objetivos de este estudio fueron determinar el desempeño del panel BCID de FilmArray® y establecer el impacto de estos resultados en el tratamiento antimicrobiano de pacientes con bacteriemia en 11 hospitales de Latinoamérica. Se incluyeron 397 episodios de bacteriemia y se documentaron 551 microorganismos aislados de hemocultivos. La identificación microbiana fue correcta en el 91,4% (504/551) de los aislados y en el 98,6% (504/511) si se consideran solo los microorganismos incluidos en el panel BCID. La sensibilidad en la detección de los genes mecA, vanA/B y blaKPC fue del 100% y la especificidad fue del 97%, 100% y 99,6% respectivamente. La notificación temprana del resultado permitió cambios terapéuticos en 242 episodios (60,9%). El panel BCID es un método confiable y rápido para la detección de mecanismos críticos de resistencia y de los microorganismos más frecuentemente aislados de bacteriemias y permite la optimización temprana del tratamiento antimicrobiano.

Abstract The objectives of this study were to determine the performance of the BCID panel and to establish the impact of these results on the antimicrobial treatment of patients with bacteremia in 11 hospitals in Latin America. Three hundred and ninety-seven episodes of bacteremia were included and 551 microorganisms isolated from blood cultures were documented. Microbial identification was correct in 91.4% (504/551) of the isolates and in 98.6% (504/511) if only the microorganisms included in the BCID panel are considered. The sensitivity in the detection of the genes mecA, vanA/B and blaKPC was 100% and the specificity was 97%, 100% and 99.6% respectively. Early notification of the outcome allowed therapeutic changes in 242 episodes (60.9%). The BCID panel is a reliable and rapid method for the detection of critical resistance mechanisms and of the microorganisms most frequently isolated from bacteremia and it enables early optimisation of antimicrobial treatment.

Resumo Os objetivos deste estudo foram determinar o desempenho do painel BCID do FilmArray® e estabelecer o impacto desses resultados no tratamento antimicrobiano de pacientes com bacteremia em 11 hospitais da América Latina. Trezentos e noventa e sete episódios de bacteremia foram incluídos e 551 microrganismos isolados de hemoculturas foram documentados. A identificação microbiana foi correta em 91,4% (504/551) dos isolados e em 98,6% (504/511) considerando apenas os microrganismos incluídos no painel BCID. A sensibilidade na detecção dos genes mecA, vanA/B e blaKPC foi de 100% e a especificidade foi de 97%, 100% e 99,6% respectivamente. A notificação precoce do desfecho permitiu mudanças terapêuticas em 242 episódios (60,9%). O painel BCID é um método confiável e rápido para a detecção de mecanismos críticos de resistência e dos microrganismos mais frequentemente isolados da bacteremia e permite a otimização precoce do tratamento antimicrobiano.

The dilemma of identifying Peptoniphilus species by using two MALDI-TOF MS systems.

Two commercial MALDI-TOF MS systems were used to identify 18 isolates, belonging to the Peptoniphilus genus; also the 16S rRNA sequencing identity was compared against the MALDI-TOF MS system results. Bruker Biotyper system provided higher accuracy than Vitek MS system, however, adding spectra could allow a more reliable species level identification.

Glutamato deshidrogenasa: Su valor diagnóstico en la diarrea por Clostridioides difficile / Glutamate dehydrogenase: Its diagnostic value in Clostridioides difficile diarrhea

Clostridioides difficile es el principal agente causal de diarreas asociadas al cuidado de la salud. Esta bacteria produce toxinas y una enzima que se encuentra muy conservada en la especie: la glutamato deshidrogenasa (GDH). El diagnóstico rápido y el tratamiento efectivo permiten la pronta mejoría del paciente, con el consecuente control de la diseminación del microorganismo. Sin embargo, aún no se cuenta con un método diagnóstico óptimo y se propone la realización de diversas pruebas, cuyos resultados se interpretan en el contexto de ciertos algoritmos. En este trabajo se evaluó el desempeño de la GDH como prueba de tamizaje en el diagnóstico de la diarrea por c. difficile. Se estudiaron 615 muestras de materia fecal. Se determinó la presencia de GDH y de toxinas mediante el equipo diagnóstico de enzimoinmunoensayo de membrana C. DIFF QUIK-CHEK COMPLETE® (TECHLAB) y se realizaron cultivos para la búsqueda de C. difficile. Se calcularon los valores de sensibilidad, especificidad, VPP y VPN con un nivel de significación p < 0,05. Se detectó GDH en 266 muestras (43,25%), con una sensibilidad del 100% y una especificidad del 87,10%, IC95: 84,58-91,42. Se hallaron toxinas en 218 muestras (35,45%) y C. difficile desarrolló en 235 cultivos (38,21%). De 48 muestras GDH positivas y sin producción de toxina/s, 17 fueron positivas al cultivo de C. difficile, con 15 aislamientos toxigénicos y 2 no toxigénicos. No hubo desarrollo de C. difficile en las 31 muestras restantes. Ninguna muestra GDH negativa dio resultado positivo de toxina/s ni desarrollo en el cultivo, por lo cual el VPN de la GDH fue del 100%, mientras que el VPP fue del 81,9%. Concluimos que la determinación de GDH representa un screening adecuado para descartar casos de diarrea por C. difficile, por lo tanto de valor en los algoritmos diagnósticos de las diarreas infecciosas.

Clostridioides difficile is the main etiological agent of diarrhea associated with health care, it produces toxins and glutamate dehydrogenase (GDH), an enzyme that is highly conserved in this species. Rapid diagnosis and effective treatment produce prompt improvement of the patient and subsequent control of the microorganism spread. There are several techniques whose results are interpreted in the context of algorithms. However, the optimal diagnostic method is yet unknown. The performance of GDH as a screening test for the diagnosis of C. difficile diarrhea was assessed. Six hundred and fifteen stool samples were studied. The presence of GDH and toxins presence was determined by TECHLAB® C. DIFF QUIK-CHEK COMPLETE and the samples were cultured for the search of C. difficile. The values of sensitivity, specificity, PPV and NPV were calculated with a p value of 0.05 or less. GDH was detected in 266 samples (43.25%), with a sensitivity of 100% and specificity of 87.10%, IC95: 84.58-91.42; toxin/s were detected in 218 (35.45%) and C. difficile developed in 235 cultures (38.21%). From 48 samples with positive GDH and negative toxin/s, 15 toxigenic and 2 non-toxigenic isolates were obtained, the remaining 31 samples were negative for C. difficile. All GDH-negative samples were negative for toxins or culture, therefore, GDH NPV was 100%, while PPV was 81.9%. We conclude that GDH is a suitable screening test for the diagnostic algorithm of C. difficile diarrhea.

Detection of toxigenic Clostridioides --#1;Clostridium--#3; difficile: Usefulness of two commercially available enzyme immunoassays and a PCR assay on stool samples and stool isolates / Detección de Clostridioides --#1;Clostridium--#3; difficile toxigénico: utilidad de dos métodos de enzimoinmunoensayo comerciales y una PCR en las muestras de materia fecal y en los respectivos aislamientos

The best laboratory diagnostic approach to detect Clostridioides --#1;Clostridium--#3; difficile infection (CDI) is a subject of ongoing debate. With the aim of evaluating four laboratory diagnostic methods, 250 unformed stools from patients with suspected CDI submitted to nine medical center laboratories from November 2010 to December 2011, were studied using: (1) an immunochromatographic rapid assay test that combines the qualitative determination of glutamate dehydrogenase (GDH) plus toxins A and B (QAB), the CDIFF QUIK CHEK COMPLETE assay; (2) an enzyme immunoassay for qualitative determination of toxins A and B, the RIDASCREENTC. difficile Toxin A/B assay (RAB); (3) a PCR for the toxin B gene assay (PCR); and (4) the toxigenic culture (TC).C. difficile isolates from direct toxin negative stools by QAB, RAB and PCR were evaluated for toxigenicity by the same direct tests, in order to assess the contribution of the TC (QAB-TC, RAB-TC, PCR-TC). A combination of the cell culture cytotoxicity neutralization assay (CCCNA) in stools, and the same assay on isolates from direct negative samples (CCCNA-TC) was considered the reference method (CCCNA/CCCNA-TC). Of the 250 stools tested, 107 (42.8%) were positive by CCCNA/CCCNA-TC. The GDH and PCR/PCR-TC assays were the most sensitive, 91.59% and 87.62%, respectively. The QAB, RAB, QAB/QAB-TC and RAB/RAB-TC had the highest specificities, ca. 95%. A negative GDH result would rule out CDI, however, its low positive likelihood ratio (PLR) of 3.97 indicates that a positive result should always be complemented with the detection of toxins. If the RAB, QAB, and PCR assays do not detect toxins from direct feces, the toxigenic culture should be performed. In view of our results, the most accurate and reliable methods to be applied in a clinical microbiology laboratory were the QAB/QAB-TC, and RAB/RAB-TC, with PLRs >10 and negative likelihood ratios <0.30.

El mejor procedimiento para realizar el diagnóstico de laboratorio de la infección causada por Clostridioides --#1;Clostridium--#3; difficile (ICD) es aún objeto de debate. Con el fin de evaluar cuatro métodos diagnósticos de laboratorio, se estudiaron 250 muestras de heces diarreicas provenientes de pacientes con sospecha de ICD remitidas a los laboratorios de nueve centros médicos entre noviembre de 2010 y diciembre de 2011. Dichas muestras se analizaron mediante los siguientes métodos:1) un ensayo rápido inmunocromatográfico que combina la detección cualitativa de la glutamato deshidrogenasa (GDH) y de las toxinas Ay B (QAB), CDIFF QUIK CHEK COMPLETE;2) un enzimoinmunoanálisis para la determinación cualitativa de las toxinas A/B, RIDASCREENTC. difficile Toxin A/B (RAB);3) un método molecular basado en PCR para la detección del gen que codifica la toxina B (PCR) y 4) el cultivo toxigénico (TC). Como método de referencia se utilizó la combinación del ensayo de citotoxicidad sobre cultivo de células con la neutralización de toxina mediante anticuerpo específico en los filtrados de las heces (CCCNA) y el mismo método en sobrenadantes de aislamientos de C. difficile (CCCNA-TC). La toxigenicidad de las cepas aisladas de muestras directas negativas con QAB, RAB y PCR se evaluó con los mismos métodos, con el propósito de detectar la contribución del TC (QAB-TC, RAB-TC, PCR-TC). De las 250 muestras estudiadas, 107 (42,8%) fueron positivas por CCCNA/CCCNA-TC. Los métodos GDH y PCR/PCR-TC fueron los más sensibles: 91,59 y 87,62%, respectivamente. Los métodos QAB, RAB, QAB/QAB-TC y RAB/RAB-TC mostraron las mayores especificidades, del 95%, aproximadamente. Un resultado negativo para GDH excluiría la ICD, pero su baja razón de verosimilitud positiva (PLR), que fue 3,97, indica que un resultado positivo debe complementarse con la detección de toxinas. Cuando no se detectan toxinas directas por RAB, QAB ni PCR, debería realizarse el TC. De acuerdo con nuestros resultados, los métodos más precisos y confiables para ser aplicados en un laboratorio de microbiología clínica son QAB/QAB-TC y RAB/RAB-TC, con una PLR> 10 y una razón de verosimilitud negativa < 0,30.

Detection of toxigenic Clostridioides [Clostridium] difficile: Usefulness of two commercially available enzyme immunoassays and a PCR assay on stool samples and stool isolates.

The best laboratory diagnostic approach to detect Clostridioides [Clostridium] difficile infection (CDI) is a subject of ongoing debate. With the aim of evaluating four laboratory diagnostic methods, 250 unformed stools from patients with suspected CDI submitted to nine medical center laboratories from November 2010 to December 2011, were studied using: (1) an immunochromatographic rapid assay test that combines the qualitative determination of glutamate dehydrogenase (GDH) plus toxins A and B (QAB), the CDIFF QUIK CHEK COMPLETE assay; (2) an enzyme immunoassay for qualitative determination of toxins A and B, the RIDASCREEN™ C. difficile Toxin A/B assay (RAB); (3) a PCR for the toxin B gene assay (PCR); and (4) the toxigenic culture (TC). C. difficile isolates from direct toxin negative stools by QAB, RAB and PCR were evaluated for toxigenicity by the same direct tests, in order to assess the contribution of the TC (QAB-TC, RAB-TC, PCR-TC). A combination of the cell culture cytotoxicity neutralization assay (CCCNA) in stools, and the same assay on isolates from direct negative samples (CCCNA-TC) was considered the reference method (CCCNA/CCCNA-TC). Of the 250 stools tested, 107 (42.8%) were positive by CCCNA/CCCNA-TC. The GDH and PCR/PCR-TC assays were the most sensitive, 91.59% and 87.62%, respectively. The QAB, RAB, QAB/QAB-TC and RAB/RAB-TC had the highest specificities, ca. 95%. A negative GDH result would rule out CDI, however, its low positive likelihood ratio (PLR) of 3.97 indicates that a positive result should always be complemented with the detection of toxins. If the RAB, QAB, and PCR assays do not detect toxins from direct feces, the toxigenic culture should be performed. In view of our results, the most accurate and reliable methods to be applied in a clinical microbiology laboratory were the QAB/QAB-TC, and RAB/RAB-TC, with PLRs >10 and negative likelihood ratios <0.30.

[Glutamate dehydrogenase. Its diagnostic value in Clostridioides difficile diarrhea]. / Glutamato deshidrogenasa. Su valor diagnóstico en la diarrea por Clostridioides difficile.

Clostridioides difficile is the main etiological agent of diarrhea associated with health care, it produces toxins and glutamate dehydrogenase (GDH), an enzyme that is highly conserved in this species. Rapid diagnosis and effective treatment produce prompt improvement of the patient and subsequent control of the microorganism spread. There are several techniques whose results are interpreted in the context of algorithms. However, the optimal diagnostic method is yet unknown. The performance of GDH as a screening test for the diagnosis of C. difficile diarrhea was assessed. Six hundred and fifteen stool samples were studied. The presence of GDH and toxins presence was determined by TECHLAB® C. DIFF QUIK-CHEK COMPLETE and the samples were cultured for the search of C. difficile. The values of sensitivity, specificity, PPV and NPV were calculated with a p value of 0.05 or less. GDH was detected in 266 samples (43.25%), with a sensitivity of 100% and specificity of 87.10%, IC95: 84.58-91.42; toxin/s were detected in 218 (35.45%) and C. difficile developed in 235 cultures (38.21%). From 48 samples with positive GDH and negative toxin/s, 15 toxigenic and 2 non-toxigenic isolates were obtained, the remaining 31 samples were negative for C. difficile. All GDH-negative samples were negative for toxins or culture, therefore, GDH NPV was 100%, while PPV was 81.9%. We conclude that GDH is a suitable screening test for the diagnostic algorithm of C. difficile diarrhea.

Causa inusual de meningitis en pacientes infectados por HIV-1 / Unusual cause of meningitis in HIV-1 infectedpatient6. Corredoira J, Garcia-Garrote F, Rabuñal R, et al. Association between bacteremia due to Streptococcus gallolyticus subsp. gallolyticus (S. bovis I) and colorectal neoplasia: a case-control study. Clin Infect Dis 2012; 55:491-967. Sheng WH, Chuang YC, Teng LJ, Hsueh PR. Bacteremia due to Streptococcus gallolyticus subspecies pasteuri

La infección por HIV suele ser un campo propicio para la aparición de complicaciones de causas inusuales, entre ellas, las infecciones por gérmenes extremadamente infrecuentes. Las distintas subespecies de Streptococcus bovis suelen presentarse como bacteriemias o endocar-ditis asociadas, con mucha frecuencia, a tumores benignos o malignos de las regiones colorrectal, gástrica, pancreática o hepatobiliar.Se presenta un caso raro de meningitis por Streptoccocus gallolyticusen un paciente adulto infectado por HIV, sin evidencia alguna de las asociaciones o localizaciones mencionadas y con características clíni-cas y licuorales que pueden inducir a pensar en diagnósticos distintos y, por ende, a tratamientos no apropiados.Un sistema inmunológico deteriorado suele ser el escenario determi-nante para la emergencia de estas raras complicaciones

HIV infectionis, usually, a favorable field for the development of complications from unusual causes including infections with extremely raregerms. The different subspecies of Streptococcus bovis often present as bacteriemias or endocarditis, most frequently associated with benign or malignant tumors of the colorectal, gastric, pancreatic or hepatobiliary regions.A rare case of meningitis due to Streptoccocus gallolyticus in an adult patient infected by HIV is presented without any evidence of associations or mentioned locations and with clinical and the cerebrospinal fluid features that induce to other diagnoses and subsequent inappropriate treatment.A deteriorated immune system is the determining factor for the emergence of these rare complications

[Rhodococcus equi infection in AIDS patients: retrospective analysis of 13 patients in Argentina]. / Infección por Rhodococcus equi en pacientes con SIDA: Análisis retrospectivo de 13 pacientes en Argentina.

INTRODUCTION: Rhodococcus equi is a gram positive coccoid rod that causes pulmonary infections in immunosuppressed patients. METHODS: We retrospectively analyzed epidemiological, clinical, microbiological, radiological, and immunological features as well as the outcomes of 13 AIDS patients with R. equi infection. RESULTS: Between January 1994 and December 2012, 13 patients attending the AIDS department of the Infectious Diseases reference hospital in Buenos Aires were diagnosed with R. equi infection. All were men, the median age was 27 years. At the time of diagnosis, the median of CD4+ T cell counts was 11 cells/µl Twelve patients presented pulmonary disease with isolation of the microorganism from sputum or bronchoalveolar lavage; in the other patient the diagnosis was postmortem with positive culture of cerebrospinal fluid. The most frequent clinical manifestations were fever, haemoptysis, and weight loss. The predominant radiological finding was lobe consolidation with cavitation. Nine patients died after a median survival of 5.5 months. In all of them, cultures persisted positive until the last admission. The other 4 patients did continue clinical follow-ups. CONCLUSION: The insidious course of R. equi disease and the difficulties in the isolation of the microorganism contribute to the delay in the diagnosis and to the high mortality rate of this opportunistic infection.

Infección por Rhodococcus equi en pacientes con SIDA: Análisis retrospectivo de 13 pacientes en Argentina / Rhodococcus equi infection in AIDS patients: Retrospective analysis of 13 patients in Argentina

Introduction: Rhodococcus equi is a gram positive coccoid rod that causes pulmonary infections in immunosuppressed patients. Methods: We retrospectively analyzed epidemiological, clinical, microbiological, radiological, and immunological features as well as the outcomes of 13 AIDS patients with R. equi infection. Results: Between January 1994 and December 2012, 13 patients attending the AIDS department of the Infectious Diseases reference hospital in Buenos Aires were diagnosed with R. equi infection. All were men, the median age was 27 years. At the time of diagnosis, the median of CD4+ T cell counts was 11 cells/μl Twelve patients presented pulmonary disease with isolation of the microorganism from sputum or bronchoalveolar lavage; in the other patient the diagnosis was postmortem with positive culture of cerebrospinal fluid. The most frequent clinical manifestations were fever, haemoptysis, and weight loss. The predominant radiological finding was lobe consolidation with cavitation. Nine patients died after a median survival of 5.5 months. In all of them, cultures persisted positive until the last admission. The other 4 patients did continue clinical follow-ups. Conclusion: The insidious course of R. equi disease and the difficulties in the isolation of the microorganism contribute to the delay in the diagnosis and to the high mortality rate of this opportunistic infection.

Introducción: Rhodococcus equi es un cocobacilo grampositivo que provoca compromiso pulmonar en pacientes inmunodeprimidos. Métodos: En el presente trabajo se analizaron de manera retrospectiva los hallazgos epidemiológicos, clínicos, microbiológicos, imagenológicos, inmunológicos y la evolución de 13 pacientes con SIDA y enfermedad por R. equi. Resultados: Entre enero de 1994 y diciembre de 2012, 13 pacientes internados en la División de VIH/SIDA del hospital de referencia para Enfermedades Infecciosas de la ciudad de Buenos Aires egresaron con diagnóstico de enfermedad por R. equi. Todos eran varones y la mediana de edad fue 27 años. La mediana de linfocitos T CD4+ fue de 11 céls/μl Doce pacientes presentaron enfermedad pulmonar con aislamiento del microorganismo del esputo o del lavado bronco-alveolar; en el restante se recibió post mortem el cultivo positivo de líquido cefalorraquídeo. Las manifestaciones clínicas más frecuentes fueron fiebre, hemoptisis y pérdida de peso. La imagen radiológica predominante fue la consolidación con cavitación. Nueve pacientes fallecieron, con una mediana de supervivencia de 5,5 meses. En todos ellos el cultivo persistió positivo hasta la última internación. Los cuatro restantes abandonaron los controles y no pudieron ser evaluados en el tiempo. Conclusión: El curso insidioso de la enfermedad por R. equi y las dificultades en la identificación del microorganismo, contribuyen al retardo en el diagnóstico y a la elevada mortalidad de esta infección oportunista en esta población de pacientes.

First national survey of antibiotic susceptibility of the Bacteroides fragilis group: emerging resistance to carbapenems in Argentina.

The antibiotic susceptibility rates of 363 clinical Bacteroides fragilis group isolates collected from 17 centers in Argentina during the period from 2006 to 2009 were as follows: piperacillin-tazobactam, 99%; ampicillin-sulbactam, 92%; cefoxitin, 72%; tigecycline, 100%; moxifloxacin, 91%; and clindamycin, 52%. No metronidazole resistance was detected in these isolates during this time period. Resistance to imipenem, doripenem, and ertapenem was observed in 1.1%, 1.6%, and 2.3% of B. fragilis group strains, respectively. B. fragilis species showed a resistance profile of 1.5% to imipenem, 1.9% to doripenem, and 2.4% to ertapenem. This is the first report of carbapenem resistance in Argentina. The cfiA gene was present in 8 out of 23 isolates, all of them belonging to the B. fragilis species and displaying reduced susceptibility or resistance to carbapenems (MICs ≥ 4 µg/ml). Three out of eight cfiA-positive isolates were fully resistant to carbapenems, while 5 out of 8 isolates showed low-level resistance (MICs, 4 to 8 µg/ml). The inhibition by EDTA was a good predictor of the presence of metallo-ß-lactamases in the fully resistant B. fragilis strains, but discrepant results were observed for low-level resistant isolates. B. fragilis was more susceptible to antimicrobial agents than other Bacteroides species. Bacteroides vulgatus species was the most resistant to ampicillin-sulbactam and piperacillin-tazobactam, and B. thetaiotaomicron/ovatus strains showed the highest level of resistance to carbapenems, with an unknown resistance mechanism. B. vulgatus and the uncommon non-Bacteroides fragilis species were the most resistant to moxifloxacin, showing an overall resistance rate of 15.1%.

[First Argentine consensus guidelines for in vitro antimicrobial susceptibility testing of clinically relevant anaerobic bacteria in humans/ Anaerobic Subcommittee of the Asociación Argentina de Microbiología]. / Primer consenso argentino para el estudio de la sensibilidad in vitro a los antimicrobianos de las bacterias anaerobias de importancia clínica en humanos.

Through time, anaerobic bacteria have shown good susceptibility to clinically useful antianaerobic agents. Nevertheless, the antimicrobial resistance profile of most of the anaerobic species related to severe infections in humans has been modified in the last years and different kinds of resistance to the most active agents have emerged, making their effectiveness less predictable. With the aim of finding an answer and for the purpose of facilitating the detection of anaerobic antimicrobial resistance, the Anaerobic Subcommittee of the Asociación Argentina de Microbiología developed the First Argentine consensus guidelines for in vitro antimicrobial susceptibility testing of clinically relevant anaerobic bacteria in humans. This document resulted from the compatibilization of the Clinical and Laboratory Standards Institute recommendations, the international literature and the work and experience of the Subcommittee. The Consensus document provides a brief taxonomy review, and exposes why and when anaerobic antimicrobial susceptibility tests should be conducted, and which antimicrobial agents can be used according to the species involved. The recommendations on how to perform, read and interpret in vitro anaerobic antimicrobial susceptibility tests with each method are exposed. Finally, the antibiotic susceptibility profile, the classification of antibiotics according to their in vitro activities, the natural and acquired mechanisms of resistance, the emerging resistance and the regional antibiotic resistance profile of clinically relevant anaerobic species are shown.

Velocidad bactericida del suero: propuesta metodológica para precedir la eficacia de la terapia antimicrobiana / Serum bactericidal rate: metodologic proposal to predict the efficacy of antimicrobial therapy

Se propone a la Velocidad Bactericida del Suero (VBS) como una técnica complementaria a la determinación de la "curva de muerte", al poder bactericida del suero (PBS), o a la concentración bactericida mínima (CIM), y que toma de esos métodos las características más ventajosas. Se basa fundamentalmente en cuantificar a distintos tiempos la sobrevida del inóculo bacteriano expuesto al suero del paciente. De esta manera, se evalúa la velocidad de bactericida producida en las primeras horas de contacto con el microorganismo (como en la "curva de muerte") pero a la concentración de droga que ha alcanzado el paciente en estudio (como en el PBS). Algunos ensayos preliminares sugieren que la VBS tendría mayor capacidad para discriminar la respuesta de un agente infeccioso a distintos esquemas terapéuticos que la que tendrían otras determinaciones, si bien se requieren estudios prospectivos para evaluar su valor predictivo.

Velocidad bactericida del suero: propuesta metodológica para precedir la eficacia de la terapia antimicrobiana / Serum bactericidal rate: metodologic proposal to predict the efficacy of antimicrobial therapy

Se propone a la Velocidad Bactericida del Suero (VBS) como una técnica complementaria a la determinación de la "curva de muerte", al poder bactericida del suero (PBS), o a la concentración bactericida mínima (CIM), y que toma de esos métodos las características más ventajosas. Se basa fundamentalmente en cuantificar a distintos tiempos la sobrevida del inóculo bacteriano expuesto al suero del paciente. De esta manera, se evalúa la velocidad de bactericida producida en las primeras horas de contacto con el microorganismo (como en la "curva de muerte") pero a la concentración de droga que ha alcanzado el paciente en estudio (como en el PBS). Algunos ensayos preliminares sugieren que la VBS tendría mayor capacidad para discriminar la respuesta de un agente infeccioso a distintos esquemas terapéuticos que la que tendrían otras determinaciones, si bien se requieren estudios prospectivos para evaluar su valor predictivo. (AU)