Wooden sticks for plaque streaking and microbiological inoculation might be more cost- effective, but is its large scale use feasible? Quality control methods and proof of concept / Métodos de controle de qualidade e prova de conceito para a utilização de palitos de madeira em microbiologia podem ser mais econômicas, mas seu uso em larga escala é viável? Método de controle de qualidade e prova de conceito

The loop is a material classically used in the laboratory for the purpose of plate streaking and handling biological materials. However, metal loops techniques might be time consuming, considering the amount of time spent to guarantee its cooling process through each inoculation. Furthermore, plastic loops may also represent environmental issues during its production and discard process and can also represent higher costs for the laboratory. Thus, in situations of limited resources, even the simplest materials can be restricted due to logistical and budgetary issues, especially in developing countries. Inspired by demands like these, facing an occasional shortage of supply of laboratory plastic handles, we hereby present a quality control for sterilization methods and cost-effectiveness studies towards the use of wooden sticks in a Latin American country and we discuss the possibility of the large-scale use of this technique.

A alça calibrada é um material usado classicamente em laboratório para fins de inoculação em placas e manuseio de materiais biológicos. No entanto, as técnicas de alças metálicas podem consumir muito tempo, considerando a quantidade de tempo gasto para garantir seu processo de resfriamento a cada inoculação. Além disso, alças de plástico também podem representar questões ambientais durante o processo de produção e descarte e também podem representar custos mais altos para o laboratório. Assim, em situações de recursos limitados, até os materiais mais simples podem ser restringidos devido a questões logísticas e orçamentárias, especialmente nos países em desenvolvimento. Inspirados por demandas como essas, diante de uma escassez ocasional de suprimentos de alças de plástico de laboratório, apresentamos um controle de qualidade para métodos de esterilização e estudos de custo-efetividade para o uso de varas de madeira em um país latino-americano e discutimos a possibilidade de grande uso em escala dessa técnica.

Agar de capa delgada: Una opción costo-efectiva para el diagnóstico rápido de tuberculosis multirresistente / Thin layer agar represents a cost-effective alternative for the rapid diagnosis of multi-drug resistant tuberculosis

Objetivo Realizar un análisis de costo efectividad comparando el método de cultivo en agar de capa delgada y el método estándar de proporciones múltiples, utilizados en el diagnóstico de Tuberculosis Multi-drogorresistente (TB MDR). Métodos Estudio de evaluación económica en el cual se evalúan los costos y la efectividad de dos pruebas diagnósticas, ejecutado en la Corporación para Investigaciones Biológicas-CIB en Medellín, Colombia. Resultados Se evaluaron 100 pacientes, encontrando una prevalencia de resistencia a la Rifampicina de 10,8 % y resistencia a Isoniazida de 14,3 %. Se presenta un análisis en términos de costo-efectividad mediante el diseño de un árbol de decisiones (Treeage Pro ®), resultando ser la prueba basada en cultivo en agar de capa delgada más costo-efectiva; con valores de sensibilidad, especificidad y predictivos del 100 % para detectar resistencia a Rifampicina e Isoniazida. El valor del método de las proporciones múltiples fue calculado en US$ 71, con una media de tiempo para ser reportado de 49 días versus US$ 18 y 14 días respectivamente para el cultivo en agar de capa delgada. Discusión Se han desarrollado nuevas tecnologías para el diagnóstico de Tuberculosis, aparentemente más rápidas y efectivas, que deben ser evaluadas no solo en sus características operativas, sino también en términos de costo-efectividad. El presente estudio establece que el empleo de la capa delgada es menos costoso, igualmente efectivo, y puede aportar resultados más rápidamente; cuando se compara con el método tradicional. Esto implica, entre otros aspectos, que el paciente pueda recibir más oportunamente el tratamiento dirigido para TB MDR.

Objective Using cost-benefit analysis for comparing the thin-layer agar culture method to the standard multiple proportion method used in diagnosing multidrug-resistant tuberculosis (MDR TB). Methods A cost-benefit evaluation of two diagnostic tests was made at the Corporación para Investigaciones Biológicas (CIB) in Medellín, Colombia. Results 100 patients were evaluated; 10.8 % rifampicin resistance and 14.3 % isoniazid resistance were found. A computer-based decision tree model was used for cost-effectiveness analysis (Treeage Pro); the thin-layer agar culture method was most cost-effective, having 100 % sensitivity, specificity and predictive values for detecting rifampicin and isoniazid resistance. The multiple proportion method value was calculated as being US$ 71 having an average 49 day report time compared to US$ 18 and 14 days for the thin-layer agar culture method. Discussion New technologies have been developed for diagnosing tuberculosis which are apparently faster and more effective; their operating characteristics must be evaluated as must their effectiveness in terms of cost-benefit. The present study established that using thin-layer agar culture was cheaper, equally effective and could provide results more quickly than the traditional method. This implies that a patient could receive MDR TB treatment more quickly.

A novel low-cost method for Mycobacterium avium subsp. paratuberculosis DNA extraction from an automated broth culture system for real-time PCR analysis

PCR is a highly accurate technique for confirming the presence of Mycobacterium avium subsp. paratuberculosis (Map) in broth culture. In this study, a simple, efficient, and low-cost method of harvesting DNA from Map cultured in liquid medium was developed. The proposed protocol (Universidad Austral de Chile [UACH]) was evaluated by comparing its performance to that of two traditional techniques (a QIAamp DNA Stool Mini Kit and cethyltrimethylammonium bromide [CTAB] method). The results were statistically assessed by agreement analysis for which differences in the number of cycles to positive (CP) were compared by Student's t-test for paired samples and regression analysis. Twelve out of 104 fecal pools cultured were positive. The final PCR results for 11 samples analyzed with the QIAamp and UACH methods or ones examined with the QIAamp and CTAB methods were in agreement. Complete (100%) agreement was observed between data from the CTAB and UACH methods. CP values for the UACH and CTAB techniques were not significantly different, while the UACH method yielded significantly lower CP values compared to the QIAamp kit. The proposed extraction method combines reliability and efficiency with simplicity and lower cost.

Assessing new strategies for TB diagnosis in low- and middle-income countries

In this manuscript, we report the current situation of tuberculosis globally and in Brazil, the need for new strategies toward tuberculosis control, focusing on new diagnostic technologies. Critical comments are given on the state of the art regarding the evaluation of new health technologies, degree of scientific evidence needed, evaluation of clinical impact, cost-effectiveness of incorporation into the health system and the social impact.

Bacterial identification in the diagnostic laboratory: How much is enough.

The major impetus for bacterial identification came after the advent of solid culture media. Morphological appearance of bacterial colonies was often sufficient for their identification in the laboratory. Even in modern times, preliminary identification of most cultivable bacteria is based on such morphological characters. Advances have been made media for the presumptive identifi cation of common organisms encountered in clinical samples. Phenotypic characterisation of bacteria with, physiological tests with a battery of biochemical tests differentiate related bacterial genera as well as confirm their identity. . Each laboratory can select its own method(s) of identification, provided they are based on scientific / epidemiological evidence; clinical laboratory and standards institute (CLSI) is a widely accepted organization and laboratories in many parts of the world follow its recommendations for bacterial identification. Some of the latest advances in identification include Matrix Assisted Laser Desorption Ionization - Time of Flight Mass Spectroscopy (MALDI-TOF) is a state of art facility used for fast and reliable species-specific identification of bacteria including Mycobacteria and fungi including yeasts. However the single most important factor that decides the method of bacterial identification in any laboratory is the cost involved. In the final analysis, selection of tests for bacterial identification should be based on their standardization with proper scientific basis. Considering the cost and lack of easy availability of commercial kits, we have put forward a simplified and rapid method of identification for most commonly encountered bacterial pathogens causing human infection in India

Análisis de costos de los métodos rápidos para diagnóstico de Tuberculosis multidrogorresistente en diferentes grupos epidemiológicos del Perú / Cost analysis of rapid methods for diagnosis of multidrug resistant Tuberculosis in different epidemiologic groups in Perú

Objetivos. Evaluar los costos de tres métodos diagnósticos para susceptibilidad a drogas antituberculosas y comparar el costo por caso de tuberculosis multidrogorresistente (TB MDR) diagnosticado con estos (MODS; GRIESS y Genotype MTBDR plus ® en cuatro grupos epidemiológicos en el Perú. Materiales y métodos. En base a cifras programáticas, se dividió a la población en cuatro grupos: pacientes nuevos de Lima/Callao; nuevos de otras provincias; los antes tratados de Lima/Callao y de otras provincias. Se calcularon los costos de cada prueba en base a la metodología estándar utilizada por el Ministerio de Salud, desde la perspectiva de los servicios de salud. Basado en ello, se calculó el costo por paciente TB MDR diagnosticado para cada grupo epidemiológico. Resultados. Los costos estimados por prueba para MODS, GRIESS, y Genotype MTBDR plus ® fueron de 14,83; 15,51 y 176,41 nuevos soles, respectivamente. El costo por paciente TB MDR diagnosticado con GRIESS y MODS fue menor a los 200 nuevos soles en tres de los cuatro grupos. El costo por TB MDR diagnosticado fue de más de 2000 nuevos soles con el Genotype MTBDR plus ® en los dos grupos de pacientes nuevos y, menores a 1000 nuevos soles en los grupos de pacientes antes tratados. Conclusiones. En grupos de alta prevalencia, como son los pacientes antes tratados, los costos por caso diagnosticado de TB MDR con las tres pruebas evaluadas fueron bajos, sin embargo, con la prueba molecular en los grupos de baja prevalencia, fueron elevados. El uso de las pruebas moleculares debe optimizarse en grupos de altas prevalencias.

Objectives.To evaluate the costs of three methods for the diagnosis of drug susceptibility in tuberculosis, and to compare the cost per case of Multidrug-resistant tuberculosis (MDR TB) diagnosed with these (MODS, GRIESS and Genotype MTBDR plus ® in 4 epidemiologic groups in Peru. Materials and methods.In the basis of programmatic figures, we divided the population in 4 groups: new cases from Lima/Callao, new cases from other provinces, previously treated patients from Lima/Callao and previously treated from other provinces. We calculated the costs of each test with the standard methodology of the Ministry of Health, from the perspective of the health system. Finally, we calculated the cost per patient diagnosed with MDR TB for each epidemiologic group. Results. The estimated costs per test for MODS, GRIESS, and Genotype MTBDR plus® were 14.83. 15.51 and 176.41 nuevos soles respectively (the local currency, 1 nuevos sol=0.36 US dollars for August, 2011). The cost per patient diagnosed with GRIESS and MODS was lower than 200 nuevos soles in 3 out of the 4 groups. The costs per diagnosed MDR TB were higher than 2,000 nuevos soles with Genotype MTBDR plus ® in the two groups of new patients, and lower than 1,000 nuevos soles in the group of previously treated patients. Conclusions. In high-prevalence groups, like the previously treated patients, the costs per diagnosis of MDR TB with the 3 evaluated tests were low, nevertheless, the costs with the molecular test in the low- prevalence groups were high. The use of the molecular tests must be optimized in high prevalence areas.

Cost effectiveness of colony lysis and colony PCR methods for screening of recombinant Escherichia coli colonies--a comparative study.

Economizing the research protocols by using low cost technologies is the need of laboratories of developing world. Screening of recombinant E. coli colonies is the crucial step in gene cloning and expression studies. In the present study, the cost effectiveness of colony lysis method and colony PCR method in the screening of recombinant E. coli colonies was compared. The colony lysis method was 20 two times more cost effective and less time consuming and can be used to screen the recombinant E. coli colonies in large scale instead of colony PCR method.

Utilidad de la incubación prolongada y de los subcultivos terminales de hemocultivos de pacientes inmunocomprometidos / Utility of prolonged incubation and terminal subcultures of blood cultures from immunocompromised patients

The value of blind terminal subcultures (7 and 30 days) and prolonged incubation (30 days) of blood cultures from immunosuppressed patients was analyzed in the Fundación Favaloro, the Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia and the Hospital de Niños Ricardo GutiÚrrez. A total of 2707 blood cultures and 369 patients were included (transplantation of solid organs 154, oncohematologic disorders 106 and solid tumors 109). Bact-Alert bottles were incubated at 35 degrees C for 30 days in the Bact-Alert System. Bottles with positive signals were routinely removed, and aliquots of the broth were Gram stained and subcultured aerobically in chocolate agar and Sabouraud agar. A total of 136 bacteremic episodes were obtained. The positivization time of blood cultures was 81.6 at 24 h, 93.3 at 48 h, 94.5 at 72 h and 97.7 within 7 days. Only 3 (2.2) episodes were positive by blind terminal subcultures and 1 (0.75) by prolonged incubation (14 days). The median time and range of positivization in hours were 13.8 and 2.2-168, respectively. The microorganisms isolated were coagulase negative staphylococci (n = 24), Klebsiella pneumoniae (n = 22), Staphylococcus aureus (n = 21), Escherichia coli (n = 18), Acinetobacter spp (n = 9), Candida spp (n = 8), Pseudomonas aeruginosa (n = 6), Enterobacter cloacae (n = 5), Stenotrophomonas maltophilia (n = 5), Enterococcus faecalis, Salmonella spp and Capnocytophaga sputigena (n = 2), Enterobacter aerogenes, Enterococcus faecium, Citrobacter diversus, Candida albicans, Klebsiella oxytoca, Chryseomonas luteola, Serratia marcescens, Abiotrophia spp, Campylobacter jejuni, Moraxella catarrhalis, Moraxella urethralis, Neisseria sicca, beta hemolytic group G streptococci, Rhodococcus equi, Micrococcus spp, Cryptococcus neoformans and Streptococcus mitis (n = 1). In our experience, blind terminal subcultures and prolonged incubation of blood cultures from immunosuppressed patients are unnecessary and cost expensive.

A comparison of costs and effectiveness of the BACTEC NR-730 system and a conventional method of blood culture.

Results and costs of the first six months experience with BACTEC NR-730 were compared with a series of blood cultures performed by the conventional method previously used. The newer technology detected the growth of 14.1% of significant isolates on the day of receipt of the specimens. The previous method lacked blind subcultures on the day of receipt and therefore detected growth only after overnight incubation. No direct comparison of the sensitivities of the methods was possible, but the percentages of cultures yielding significant isolates were similar for the two methods. With the new method, technicians needed less time for daily screening of blood cultures, fewer subcultures were required and less contamination was observed. The method used to calculate the directly-related variable costs of the two methods is set out. In the particular situation reported, workload and labor costs were such that introduction of BACTEC NR-730 resulted in a saving on variable costs.

Deteccion de portadores de Salmonella Typhi mediante la prueba de hemaglutinacion indirecta con antigeno Vi muy purificado / Screening of Salmonella Typhi carriers by indirect hemagglutination using highly purified Vi antigen

A study was carrried out to determine the predictive value and the cost-effectiveness of the indirect hemagglutination test using highly purified Vi antigen as a means of screening Salmonella Typhi carrriers in a high-risk group living in an área where typhoid fever is emdemic. The group consisted of women over age 30 who were participating in a municipal sanitary control program for food handlers in Lima, Perú. Test yielding an anti-Vi antibody titer= 1:40 were considered positive (79 percent sensitivity, and 99 percent and 100 percent specificity for the local population). On this basis, 29 women (1.5 percent) tested positive out of a total of 1 931. A follow-up bacteriological study demonstrated that 26 of these 29 women were carriers of S. typhi; thus, the test had a predictive value of 15 percent. The prevalence of carriers in this group was estimated at 292 per 100 000 population. The test cost $US 0.30 per person. In comparison, the method that requires a series of three fecal cultures to isolate the causative agent would have cost $US 1.72. It can be concluded that the test studied is suficiently sensitive, that it is highly specific, and that it is cost-effective when used to detect S. typhi carriers in áreas where typhoid fever is endemic