RESUMEN
Shiga toxin-producing Escherichia coli (STEC) are important pathogens transmitted by food that may cause severe illness in human beings. Thus, systems for STEC detection in food should have increasingly higher sensitivity and specificity. Here we compared six commercial systems for non-O157 STEC detection in meat and vegetables and determined their sensitivity, specificity and repeatability. A total of 46 samples (meat nâ¯=â¯23; chard nâ¯=â¯23) were experimentally contaminated with strains O26:H11, O45:H-, O103:H2, O111:NM, O121:H19 and O145:NM isolated in Argentina. Strain detection was confirmed by isolation according to ISO 13136:2012. Detection of the stx and eae genes in meat samples was highly satisfactory with all commercial kits, but only five had 100% sensitivity and specificity in chard. Of four kits evaluated for serogroup detection, three had 100% sensitivity and specificity, and one had 93.7% sensitivity and 100% specificity. All kits were adequate to analyze meat but not vegetable samples, and were not therefore validated for the latter matrix. The challenge for microbiology laboratories is to identify the advantages and disadvantages of the available kits for STEC detection in food based on a clear knowledge of the particular needs of each laboratory.
Asunto(s)
Contaminación de Alimentos/análisis , Microbiología de Alimentos/métodos , Carne/microbiología , Serotipificación/normas , Escherichia coli Shiga-Toxigénica/aislamiento & purificación , Verduras/microbiología , Adhesinas Bacterianas/genética , Microbiología de Alimentos/normas , Juego de Reactivos para Diagnóstico/normas , Sensibilidad y Especificidad , Serogrupo , Serotipificación/métodos , Toxina Shiga/genéticaRESUMEN
Leptospirosis is a zoonotic infection caused by pathogenic members of the genus Leptospira spp. Knowledge of the prevalent serovars and their maintenance hosts is essential to understand the disease. The aim of this study was to evaluate the ability of serology by the microscopic agglutination test (MAT) to predict the serogroups compared with results of identification of leptospires in São Paulo, Brazil. MAT correctly assigned the serogroup of the infecting isolate in 49/52 cases (94.23%). The serogroup Icterohaemorrhagiae was the predominant serogroup (88.46%). This study showed the usefulness of the MAT to correctly identify the infecting serogroup with a good overall agreement between the serologically-identified infecting serogroup and by identification of the isolate and can be used in epidemiological surveys in São Paulo. However, it should be complemented by the identification of Leptospira isolates.
Asunto(s)
Pruebas de Aglutinación/normas , Leptospira interrogans serovar icterohaemorrhagiae/clasificación , Leptospira/clasificación , Leptospirosis/diagnóstico , Leptospirosis/microbiología , Serotipificación/normas , Animales , Anticuerpos Antibacterianos/sangre , Brasil/epidemiología , Humanos , Leptospira/inmunología , Leptospira/aislamiento & purificación , Leptospira interrogans serovar icterohaemorrhagiae/aislamiento & purificación , Leptospirosis/sangre , Leptospirosis/epidemiología , Estudios Retrospectivos , Serogrupo , Zoonosis/diagnósticoRESUMEN
Salmonella is a complex bacterial group with more than 2400 serovars widely distributed in nature; they are considered zoonotic because they can infect a variety of animals and be transmitted to humans. Usually, they cause alimentary acquired diseases such as gastroenteritis, typhoid fever, and others that can lead to severe complications and death. Serotyping is useful to differentiate among Salmonella, because it shows an important correlation with their clinical and epidemiological patterns; consequently, it is of high value for public health, animal health, agriculture, and industry. To characterize all known Kauffmann-White Salmonella serovars, over 250 antisera are required. Due to this and to high prices antisera, many laboratories worldwide have limitations in establishing Salmonella surveillance. Therefore, we developed and validated a Salmonella flagella microagglutination test (SALMATcor) that significantly reduces laboratory requirements of antisera. SALMATcor is based on scaling down, by fivefold, the antigen:antiserum volumes actually required for the reference method: flagella standard tube agglutination technique (STAT). Antigen preparation, temperatures, and incubation periods remained as established for STAT. The SALMATcor was validated according to ISO/DIS 16140:1999 protocol, which included 1187 comparisons of flagella determinations conducted by SALMATcor and STAT, on 141 Salmonella isolates of 12 common serotypes and the use of antiserum recommended for STAT. SALMATcor concordance was excellent (Cohen's kappa index 0.9982), obtaining relative accuracy >99.9% and relative specificity >99.9%. Additionally, SALMATcor has been used by CNRB-INCIENSA since 2004 to respond to all 40 Salmonella proficiency testing strains, provided by World Health Organization-Global Salmonella Surveillance Network, obtaining 100% concordance on serovar identification. On the basis of the results achieved with SALMATcor and considering that it also significantly reduces antiserum expenses, hand labor, glassware, and bench top and water bath space requirements (microtiter plates and micropipette tips are the only additional supplies), we envision that SALMATcor will contribute to establish a sustainable Salmonella serovar surveillance worldwide.
Asunto(s)
Pruebas de Aglutinación , Flagelos , Salmonella/clasificación , Serotipificación/métodos , Animales , Humanos , Sueros Inmunes/economía , Microquímica/métodos , Vigilancia de la Población/métodos , Salmonella/aislamiento & purificación , Intoxicación Alimentaria por Salmonella/diagnóstico , Intoxicación Alimentaria por Salmonella/microbiología , Intoxicación Alimentaria por Salmonella/prevención & control , Sensibilidad y Especificidad , Serotipificación/economía , Serotipificación/normasRESUMEN
Neisseria meningitidis isolates are conventionally classified by serosubtyping, which characterizes the reactivities of the PorA outer membrane protein variable-region (VR) epitopes with monoclonal antibodies (MAbs). A newer method (PorA VR typing) uses predicted amino acid sequences derived from DNA sequence analysis. The resulting classification schemes are not standardized, offering conflicting and sometimes irreconcilable data from the two methods. In this paper, we propose a standardization of the PorA VR typing nomenclature that incorporates serologic information from traditional PorA serosubtyping with molecular data from predicted VR sequences. We performed a comprehensive literature and database search, generating a collection of strains and DNA sequences that reflects the diversity within PorA that exists to date. We have arranged this information in a comprehensive logical model that includes both serosubtype and PorA VR type assignments. Our data demonstrate that the current panel of serosubtype-defining MAbs underestimates PorA VR variability by at least 50%. Our proposal for VR typing is informative because amino acid sequence and serologic information, when serosubtype-defining MAbs are available, can be deduced simultaneously from the PorA VR designation. This scheme will be useful in future classification and applied epidemiologic studies of N. meningitidis, being a systematic way of selecting PorA vaccine candidates and analyzing vaccine coverage and failure.
Asunto(s)
Neisseria meningitidis/clasificación , Neisseria meningitidis/genética , Porinas/genética , Serotipificación/normas , Terminología como Asunto , Secuencia de Aminoácidos , Anticuerpos Monoclonales , Antígenos Bacterianos/química , Antígenos Bacterianos/genética , Antígenos Bacterianos/inmunología , Secuencia de Bases , Epítopos , Genes Bacterianos , Humanos , Datos de Secuencia Molecular , Neisseria meningitidis/aislamiento & purificación , Porinas/química , Porinas/inmunologíaRESUMEN
The immunoperoxidase method for the rapid classification of influenza viruses in type and subtype was applied and validated for the first time in Cuba. The method is based on a rapid culture in MDCK-L cells and on the use of monoclonal antibodies for the classification in type and subtype. A pool of antibodies against influenza A and another against influenza B and HA1-71 and HA2-76 monoclonal antibodies are used for the subtyping in H1 and H3. The validation was carried out by applying this method to 21 international reference strains and to 23 human influenza virus strains that were isolated and previously classified by hemagglutination inhibition. All the strains reacted to the monoclonal antibodies according to their hemagglutinin type and subtype. 6 reference strains and 9 isolations were characterized within the H1N1 subtype: 9 reference strains and 10 isolations in the H3N2 subtype; and 6 reference strains and 4 isolations in type B. There were neither unspecific nor crossed reactions among the controls established. There was 100% of sensitivity, specificity and coincidence. The technique used proved to be fast and convenient for the characterization in type and subtype of the isolated influenza virus strains. It may substitute the classic hemagglutination inhibition method when it is required the rapid characterization of outbreaks or epidemics of acute respiratory infections, which is very important due to the high morbidity they cause mainly in risk groups and to their economic repercussion.
Asunto(s)
Anticuerpos Monoclonales , Anticuerpos Antivirales , Virus de la Influenza A/clasificación , Virus de la Influenza B/clasificación , Anticuerpos Monoclonales/aislamiento & purificación , Anticuerpos Antivirales/aislamiento & purificación , Células Cultivadas , Humanos , Técnicas para Inmunoenzimas/métodos , Técnicas para Inmunoenzimas/normas , Virus de la Influenza A/inmunología , Virus de la Influenza B/inmunología , Estándares de Referencia , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Serotipificación/métodos , Serotipificación/normas , Cultivo de VirusRESUMEN
Se serotipificaron 26 cepas de Campylobacter termofílicos por el método de hemaglutinación pasiva y se biotipificaron 62 cepas por el método de Lior. Dos cepas correspondieron al serogrupo 13/50 y otras dos expresaron antígenos del serogrupo 4; el 78 por ciento restante se distribuyó entre diferentes serogrupos; 21,7 por ciento de las cepas fueron no tipificables. Entre los biotipos, 47 (75,8 por ciento) correspondieron a C. jejuni, 44 (71 por ciento) al biotipo I, 3 (4,8 por ciento) al biotipo II; 14 (22,6 por ciento) a C. coli, 11 (17,8 por ciento) al biotipo I, 3 (4,8 por ciento) al biotipo II y 1 (1,6 por ciento) a C. lari. Las cepas de C. jejuni y C. coli resistentes al ácido nalidíxico pueden complicar la identificación (AU)
Asunto(s)
Campylobacter/clasificación , Campylobacter jejuni/aislamiento & purificación , Serotipificación/métodos , Técnicas de Tipificación Bacteriana/normas , Campylobacter jejuni/patogenicidad , Campylobacter coli/aislamiento & purificación , Infecciones por Campylobacter/diagnóstico , Serotipificación/normas , Medios de Cultivo/diagnósticoRESUMEN
Se serotipificaron 26 cepas de Campylobacter termofílicos por el método de hemaglutinación pasiva y se biotipificaron 62 cepas por el método de Lior. Dos cepas correspondieron al serogrupo 13/50 y otras dos expresaron antígenos del serogrupo 4; el 78 por ciento restante se distribuyó entre diferentes serogrupos; 21,7 por ciento de las cepas fueron no tipificables. Entre los biotipos, 47 (75,8 por ciento) correspondieron a C. jejuni, 44 (71 por ciento) al biotipo I, 3 (4,8 por ciento) al biotipo II; 14 (22,6 por ciento) a C. coli, 11 (17,8 por ciento) al biotipo I, 3 (4,8 por ciento) al biotipo II y 1 (1,6 por ciento) a C. lari. Las cepas de C. jejuni y C. coli resistentes al ácido nalidíxico pueden complicar la identificación