Evaluación de un panel reducido de cepas de leptospiras para el diagnóstico en humanos por microaglutinación (MAT) / Evaluation of a reduced panel of leptospira strains for microagglutination

Objetivo. Evaluar si el uso del panel de 19 cepas de leptospiras, sugerido por la Sociedad Internacional de Leptospirosis para la microaglutinación (MAT, por sus siglas en inglés), permite mayor confirmación de casos que el de 12 cepas. Material y métodos. Estudio observacional de corte transversal. Se estudiaron 441 muestras de sueros de pacientes de Argentina, derivadas para el diagnóstico de leptospirosis en los periodos de julio de 2009 a diciembre de 2010 y enero a octubre de 2013. Resultados. Se obtuvo el mismo resultado con el panel reducido que con el ampliado. En seis casos resultó presumiblemente infectante algún serovar del panel ampliado, aunque siempre coaglutinando con cepas del reducido. Conclusión. En Argentina, el diagnóstico de leptospirosis por MAT podría continuar realizándose con el panel reducido, lo que reduciría el costo y tiempo de diagnóstico. La información adicional que aportaría el panel ampliado está relacionada con la epidemiología, mediante un mejor conocimiento del serogrupo presumiblemente infectante.

Objective. To evaluate if the use of the 19 Leptospira strains panel suggested by the International Leptospirosis Society of World Health Organization for microagglutination allows confirmation of more cases that the 12 strains panel used in Argentina. Materials and methods. Cross-sectional observational study. We studied 441 serum samples corresponding to Argentinean patients with suspected leptospirosis derived during from July to December, 2009 and from January to October, 2013. Results. The same number of positive samples was obtained using the MAT with the 19 or 12 strains. In six cases a serovar of the expanded collection was presumably infecting, but always coagglutinated with strains of the reduced panel. Conclusion. In Argentina, the diagnosis of leptospirosis by MAT could be made using the reduced 12 strains panel, obtaining the same result in case detection as using the 19 strains panel. Additional information provided by the use of all strains could be the presumably infecting serogroup.

Standardization of ABO Antibody Titer Measurement at Laboratories in Korea

BACKGROUND: Measurement of the ABO antibody (Ab) titer is important in ABO-incompatible transplantation. However, to the best of our knowledge, no standard protocol or external survey program to measure the ABO Ab titer has been established in Korea. We investigated the current status of ABO Ab titer measurements at various laboratories in Korea and the impact of the protocol provided to reduce interlaboratory variations in the methods and results of ABO Ab titers. METHODS: The Korean external quality assessment of blood bank laboratories sent external survey samples with a questionnaire to 68 laboratories across Korea for the measurement of ABO Ab titers in May 2012. After 6 months, a second set of survey samples were sent with a standard protocol to 53 of the previously surveyed laboratories. The protocol recommended incubation at room temperature only and use of the indirect antihuman globulin method for the tube test as well as and the column agglutination test (CAT). RESULTS: Several interlaboratory variations were observed in the results, technical procedures, and methods selected for measurement. We found that 80.4% laboratories hoped to change their protocol to the provisional one. Additionally, CAT showed significantly lower variation among laboratories (P=0.006) than the tube test. CONCLUSIONS: Our study provides baseline data regarding the current status of ABO Ab titer measurement in Korea. The standard protocol and external survey were helpful to standardize the technical procedures and select methods for ABO Ab titer measurement.

Estratificación de leptospiras por municipios en Villa Clara / Stratification of leptospiras by municipality in Villa Clara province

Se estudiaron 786 sueros pareados de pacientes con sospecha clínica, con evidencia epidemiológica de leptospirosis o sin esta, por la técnica de microaglutinación (MAT), con el objetivo de identificar los serogrupos de mayor reactividad serológica y estratificarlos por municipio. Se obtuvo una positividad de 52,3 por ciento, siendo el serogrupo predominante ballum (11,8 por ciento), seguido de pomona (10,6 por ciento) e icterohaemorragiae (9,7 por ciento). El porcentaje mayor de positividad se observó en los municipios Santo Domingo (30,2 por ciento), Ranchuelo (23,3 por ciento), Encrucijada (12,6 por ciento) y Quemado (11,4 por ciento). La distribución de serogrupos según el municipio mantuvo un resultado similar a la distribución de serogrupos en general, con predominio de ballum en los 3 municipios de mayor número de casos

Comparison of the diagnostic value of local Widal slide test with imported Widal slide test.

A laboratory study comparing the Widal slide agglutination test using local antigens produced by Mekar Jaya Diagnostica (SAT-MJD) with imported antigens (Murex, Abbott) was carried out on 55 sera of typhoid fever patients with positive blood culture and 56 sera of non-typhoid febrile patients. The SAT-MJD antigens consisted of a mixture of 5 different phage-types of S. typhi dominantly found in Indonesia. This study revealed the following results: the diagnostic sensitivity of local and imported antigens was 83.93%, the diagnostic specificity of local antigens was higher than the imported antigens ie 82.14% compared with 64.28%, the diagnostic efficiency of local antigens was 82.88% compared with 73.87% of the imported antigens. The diagnostic positive and negative predictive values of the local antigens were 80.70% and 83.63%, respectively. The imported antigen revealed diagnostic positive and negative predictive values of 69.69% and 80%, respectively. The diagnostic specificity and efficiency of local antigens were significantly different (p < 0.02 and p < 0.05) from the imported antigens. The local antigens have some advantages. There was no variation in within-run and between-day test, compared with a 6.6% variation shown by the imported antigen. The test results obtained 5 minutes after mixing the serum with antigens reduced the possibility of false-positive and false-negative results. The cost of local antigens is lower than the imported antigens. Based on these data, the Widal SAT-MJD has a reliable diagnostic value and can be used in small laboratories, such as primary health centers (Puskesmas).

Serodiagnóstico de la brucelosis humana por aglutinación directa: problemas de interpretación causados por discrepancias entre resultados obtenidos con diferentes antígenos comerciales / Serodiagnosis of human brucellosis using agglutination tests: misinterpretation caused by discrepancies among results obtained with different commercial antigens

En este trabajo se comparó mediante ensayos de aglutinación, la reactividad de un mismo grupo de sueros frente a las distintas suspensiones comerciales de Brucella. Se determinó el volumen celular de 5 antígenos comerciales para aglutinación en placa (Huddleson), 1 antígeno comercial para reacción de Rosa de Bengala y los antígenos producidos por el Instituto Panamericano de Protección de Alimentos y Zoonosis (INPPAZ). Se observaron diferencias importantes de volumen celular entre los antígenos para Huddleson, pero no entre los antígenos para Rosa de Bengala. Con la reacción de Huddleson se ensayaron 11 sueros reactivos y 25 sueros de individuos no infectados. Se obtuvieron títulos aglutinantes más elevados con los antígenos de menor volumen celular que con los de mayor volumen celular. Resultados similares se obtuvieron al ensayar por aglutinación en tubo 8 sueros reactivos. Cuando se analizaron por Rosa de Bengala 24 sueros reactivos y 25 controles, los resultados correlacionaron en un 100 por ciento. Este estudio demuestra que existen diferencias de concentración celular importantes entre los antígenos analizados, confirma que dichas diferencias generan variaciones en el título aglutinante anti-Brucella obtenido con cada suero, y muestra cómo esas variaciones pueden dificultar el establecimiento de un correcto diagnóstico de la enfermedad

Enzyme-linked immunosorbent assay for leptospirosis immunoglobulin M specific antibody using surface antigen from a pathogenic Leptospira: a comparison with indirect hemagglutination and microagglutination tests.

A search for a sensitive and specific test for human leptospirosis was made by enzyme-linked immunosorbent assay for immunoglobulin M specific antibody (IgM ELISA) using a surface antigen from L.interrogans serovar bataviae, L. interrogans serovar pyrogenes and L.interogans serovar icterohaemorrhagiae. The IgM ELISA tests using each of the three antigens were evaluated in 103 sera primarily positive by microagglutination test (MA). Optical density of these IgM ELISA tests showed good correlation. The IgM ELISA using antigen from serovar bataviae was compared with MA and indirect hemagglutination (IHA) in 20 sera primarily positive by IHA, and 103 sera primarily positive by MA. IgM ELISA and IHA using antigen prepared from serovar bataviae in 103 sera positive for MA had a sensitivity of 98.06 and 92.23 per cent respectively. In 20 sera primarily positive by IHA, IgM ELISA and MA showed sensitivity of 80 and 45 per cent respectively. The surface antigen used in IgM ELISA is broadly specific making IgM ELISA a sensitive and specific test for human leptospirosis. IHA agreed more with IgM ELISA in comparison to MA. As MA is not sensitive for early infection, IHA and IgM ELISA should be in routine use in general laboratories.

Evaluation of a single Widal test in the diagnosis of enteric fever.

The usefulness of a single Widal test was evaluated in an endemic area. This test was done on 62 bacteriologically proven enteric fever cases, 69 non-enteric fever cases and healthy individuals. Using an 0 antibody cut-off of greater than or equal to 1:20, the Widal tube agglutination test yielded a sensitivity of 61% and a specificity of 88%. At a pre-test probability of around 50%, the positive predictive value was 83% and the negative predictive value was 72%. A 4% prevalence of 0 antibodies was noted in the healthy population.

Evaluation of co-agglutination (COA), counter immunoelectrophoresis (CIE), culture and direct microscopic (Dm) examination of cere-brospinal fluid (CSF) for detection of meningitis caused by common bacterial pathogens.

Cerebrospinal fluid from 260 children clinically diagnosed as meningitis were examined by Dm, culture, COA and CIE test. Dm revealed the presence of bacteria in 41 (15.8%) whereas culture showed growth of organism in 52 (20%) cases. COA and CIE test were done for the detection of antigen of H. influenzae, S. pneumoniae and N. meningitidis. Among the 3 methods viz. culture, COA and CIE test which were used for the detection of the above three organisms COA detected the maximum numbers (23.5%). COA test could detect antigen in both culture positive and culture negative CSF samples. COA test detected 100% of pneumococcal, 88.5% of H. influenzae and 66.7% of N. meningitidis antigens from CSF. Diagnosis by CIE in detecting H. influenzae and N. meningitidis antigens is inferior to culture and COA, whereas in detecting pneumococcal antigens CIE is superior to culture. So COA is a valuable, cheap, rapid and sensitive method for the diagnosis of meningitis caused by the above three organisms and when used along with culture 100% of cases can be diagnosed.