SALMATcor: microagglutination for Salmonella flagella serotyping.
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.
Duarte Martínez
Francisco
F
Instituto Costarricense de Investigación y Enseñanza en Nutrición y Salud (INCIENSA), Centro de Excelencia Regional WHO-GFN para Centro América, México y Caribe de Habla Hispana, Centro Nacional de Referencia de Bacteriología (CNRB), Tres Ríos, Cartago, Costa Rica.
Sánchez-Salazar
Luz Marina
LM
Acuña-Calvo
María Teresa
MT
Bolaños-Acuña
Hilda María
HM
Dittel-Dittel
Isis
I
Campos-Chacón
Elena
E
D000372:Agglutination Tests; D000818:Animals; D005407:Flagella; D006801:Humans; D007106:Immune Sera / Q000191:economics; D008832:Microchemistry / Q000379:methods; D011159:Population Surveillance / Q000379:methods; D012475:Salmonella / Q000145:classification* / Q000302:isolation & purification; D012478:Salmonella Food Poisoning / Q000175:diagnosis / Q000382:microbiology / Q000517:prevention & control; D012680:Sensitivity and Specificity; D012703:Serotyping / Q000191:economics / Q000379:methods* / Q000592:standards
D007106:Immune Sera