Evaluation of Commercial Antisera for Salmonella Serotyping

Abstract

We compared a set of commercial Salmonella somatic and flagellar serotyping antisera to in-house-prepared antisera from the Microbial Diseases Laboratory, California Department of Public Health, using 327 Salmonella enterica strains belonging to subgroups I, II, IIIa, IIIb, and IV. The sensitivities of Denka Seiken (Tokyo, Japan) somatic and flagellar antisera (using a tube agglutination assay) were 94.0% and 99.2%, respectively, and the specificity was 100% for both sets of sera. Polyvalent O and O1 antiserum sensitivity and specificity were >90%, with the exception of polyvalent O1 antiserum, for which sensitivity was 88.9%. When Denka Seiken flagellar antisera were used in a slide agglutination assay, the sensitivity and accuracy dropped to 88.9% and the specificity fell to 91%. Overall, Denka Seiken commercial antisera performed very well and, together with the comprehensive range of factors available, offer laboratories quality reagents suitable for serotyping strains of salmonellae.Infections caused by nontyphoidal Salmonella strains generally vary from asymptomatic conditions to a self-limiting gastroenteritis characterized by mildly watery stools, mucus, and occasionally occult or visible blood. Bacteremia occurs in ϳ1% to 4% of immunocompetent patients, and 5% to 10% of these persons will develop other extraintestinal complications, including reactive arthritis, central nervous system infections, endocarditis, osteomyelitis, and urinary tract infections (2, 5). These infections have a significant societal impact in terms of both personal suffering and economic consequences. Between 1996 and 1999, the Food-Borne Diseases Active Surveillance Network estimated that nontyphoidal Salmonella strains were responsible for ϳ1.4 million human cases of gastroenteritis per year in the United States, resulting in 168,000 physician office visits, 15,000 hospitalizations, and 400 deaths annually (6). The annual cost of these infections is estimated to range between $0.5 billion and $2.3 billion (1). These figures are based on medical expense and loss of productivity due to salmonellosis and do not include the substantial additional costs incurred by the food industry (due to product recall, litigation, etc). Although most cases of salmonellosis are sporadic, in 2004 over 120 food-borne outbreaks of salmonellosis in the United States were reported to the Centers for Disease Control and Prevention (CDC) (4). Many salmonella infections and subsequent deaths can be prevented if outbreaks are identified rapidly and epidemiologically linked food products are removed from the market. Since the strain of salmonella involved in an outbreak is typically tracked by its serotype and the molecular subtype of that serotype, it is essential that serotyping be performed with precision to ensure that all strains involved in an outbreak are recognized. Most clinical and public health laboratories rely on commercially prepared antisera to serotype salmonellae. However, in our laboratory, where we serotype between 3,600 and 5,400 salmone...

Methodologies for Salmonella enterica subsp. enterica Subtyping: Gold Standards and Alternatives

“…It is exclusively based on phenotypic characteristics. False-positive reactions may occur as a result of weak, nonspecific agglutination (78). Autoagglutination and loss of antigen expression, such as that observed with rough, nonmotile, and mucoid strains, may occasionally lead to strain untypeability, but these strains typically have little epidemiological significance.…”

Comprehensive Analysis Reveals Two Distinct Evolution Patterns of Salmonella Flagellin Gene Clusters

“…Based on White-Kauffmann scheme, the Salmonella strains have been identified by their surface antigens, on the basis of somatic (O), flagellar (H), and capsular (Vi) antigens (Brenner et al, 2000 ) and their reactivity to antisera (Schrader et al, 2008 ). Flagella ( fliC or fljB ) protein is the primary globular protein forming the filament of flagellum in the majority of Salmonella strains, which functions as a main structural subunit (Haiko and Westerlund-Wikstrom, 2013 ).…”

Propidium monoazide real-time PCR amplification for viable Salmonella species and Salmonella Heidelberg in pork

“…However, enzyme-linked immunosorbent assay (ELISA) (Kumar et al 2008), polymerase chain reaction (PCR), and real-time PCR (Gonzalez-Escalona et al 2012) can also be used. Traditional methods are time-consuming, laborious, and costly and have been shown to result in incorrect D r a f t typing in 5-8% of cases due to the loss of surface antigens (Kim et al 2006;Schrader et al 2008). The ELISA method also has many disadvantages, including crossreaction with other microbes (Lee et al 1990) and low detection limits due to the low binding capacity of the antigen-antibody complex.…”