10/20/2017 Learning Objectives Food 1.Use basic biochemical characteristics to identify Salmonella 2.Understand what conditions in foods favor Salmonella growth Chapter14 AN INTRODUCTION 3.Recognize,from symptoms and time of onset,a case of foodborne illness caused by Salmonella Salmonella species 4.Choose appropriate interventions(heat, preservatives,and formulations)to prevent the growth of Salmonella 5.Identify environmental sources of Salmonella 6.Understand the roles of Salmonella toxins and virulence factors in causing foodborne illness Outbreak Outbreak Cheesy chicken and rice frozen entrees Cheesy chicken and rice frozen entrees Spring and summer 2010 Frozen dinners can be cooked in ovens -Unopened packages revealed contamination Most prefer to use the microwave to heat with Salmonella enterica serovar Chester such meals EMLE团 -DNA fingerprint identical to the outbreak Spring and summer 2010 strain -44 cases of salmonellosis Heating meals in microwave ovens due to improperly cooked may not heat foods thoroughly cheesy chicken entre Microwaves vary in strength -40%of patients were hospitalized Microwaves cook foods unevenly No deaths reported Food should reach an internal temperature of 1650F
10/20/2017 1 Chapter 14 Salmonella species Learning Objectives 1. Use basic biochemical characteristics to identify Salmonella 2. Understand what conditions in foods favor Salmonella growth 3. Recognize, from symptoms and time of onset, a case of foodborne illness caused by Salmonella 4. Choose appropriate interventions (heat, preservatives, and formulations) to prevent the growth of Salmonella 5. Identify environmental sources of Salmonella 6. Understand the roles of Salmonella toxins and virulence factors in causing foodborne illness Outbreak Cheesy chicken and rice frozen entrées • Frozen dinners can be cooked in ovens • Most prefer to use the microwave to heat such meals • Spring and summer 2010 – 44 cases of salmonellosis - due to improperly cooked cheesy chicken entré - 40% of patients were hospitalized - No deaths reported Outbreak Cheesy chicken and rice frozen entrées • Spring and summer 2010 - Unopened packages revealed contamination with Salmonella enterica serovar Chester - DNA fingerprint identical to the outbreak strain • Heating meals in microwave ovens may not heat foods thoroughly • Microwaves vary in strength • Microwaves cook foods unevenly • Food should reach an internal temperature of 165OF
10/20/2017 Introduction Cost More Than 19,336 Salmonella species are leading causes of foodborne illness in humans $3.7 Billion Hospitalized Salmonellosis from food consumption is on the rise worldwide in2013 This increase is not a result of increased surveillance programs 1,027,561 378 Major outbreaks of foodborne patients in Died salmonellosis indicate various food types and numerous Salmonella serovars 2013 implicated in illness USDA ERS http/otias Salmonellosis is NOT JUST caused by Poultry Characteristics of the Organism In fact,meat poultry products were the source of only 33%of Salmonella outbreaks from 1998 to 2008 19th century,clinical pathologists in 19% France associated intestinal ulceration Poultry with a contagious infectious agent 67% .20th century,serological detection dairy, advanced for the O-antigen(LPS)and eggs, 14%Beef H-antigen (flagellar) produce, and Pork An antigenic scheme was developed for others the classification Now 2500 serovars of salmonellae
10/20/2017 2 • Salmonella species are leading causes of foodborne illness in humans • Salmonellosis from food consumption is on the rise worldwide • This increase is not a result of increased surveillance programs • Major outbreaks of foodborne salmonellosis indicate various food types and numerous Salmonella serovars implicated in illness Introduction Characteristics of the Organism • 19th century, clinical pathologists in France associated intestinal ulceration with a contagious infectious agent • 20th century, serological detection advanced for the O-antigen (LPS) and H-antigen (flagellar) • An antigenic scheme was developed for the classification • Now > 2500 serovars of salmonellae
10/20/2017 Biochemical Identification Biochemical Identification Facultative anaerobic gram-negative rod- ·Oxidase negative shaped bacteria ·Catalase negative Enterobacteriaceae family Produce hydrogen sulfide Most are motile but non-motile strains exist Decarboxylate lysine and ornthine Utilizes a wide range of carbon substrates Does not hydrolyze urea Grow optimally at 370C Grows on citrate as sole carbon source Catabolizes glucose and other carbohydrates with acid and gas production Biochemical Identification Most of these traits are the basis for presumptive identification of Salmonella ·Typically produce acid and gas from glucose but do not Mixed culture of Salmonella enterica on Hektoen enteri ferment lactose or sucrose in TSI,Hektoen Salmonella on XLD agar ogar.Note the black center of the roge agar,XLD agar ting hyof carbohydrate fermentation. Produce an alkaline reaction from decarboxylation of lysine to cadaverine in LIA slants Produce hydrogen sulfide gas in TSI and LIA
10/20/2017 3 Biochemical Identification • Facultative anaerobic gram-negative rodshaped bacteria • Enterobacteriaceae family • Most are motile but non-motile strains exist • Utilizes a wide range of carbon substrates • Grow optimally at 37OC • Catabolizes glucose and other carbohydrates with acid and gas production Biochemical Identification • Oxidase negative • Catalase negative • Produce hydrogen sulfide • Decarboxylate lysine and ornthine • Does not hydrolyze urea • Grows on citrate as sole carbon source Biochemical Identification • Most of these traits are the basis for presumptive identification of Salmonella • Typically - produce acid and gas from glucose but do not ferment lactose or sucrose in TSI, Hektoen agar, XLD agar - Produce an alkaline reaction from decarboxylation of lysine to cadaverine in LIA slants - Produce hydrogen sulfide gas in TSI and LIA Mixed culture of E coli and Salmonella on XLD agar Salmonella enterica on Hektoen enteric agar. Note the black center of the transparent colonies, indicating hydrogen sulfide production in the absence of carbohydrate fermentation
10/20/2017 Biochemical Identification ·eit6amaorofccelstasngeoC5c great concern in the clinic escapes detection in standard assays used in hospitals and industry lron Agar (M37 sucrose and lactose positive strains acquired gar Iron Agar (M021) richia coll ATCC 25922 genes for this phenotype via plasmids ol ATCC 25922 teu almonella Typhimurium ATCC 14028 Bismuth sulfite agar remains a medium of choice ris ATC A due to... high selectivity phiaeteysineandofomhydrogen -responds effectively to low levels of hydrogen sulfide Biochemical Identification Taxonomy and Nomenclature WHO Collaborating Centre for Reference and Research Variability in biochemical traits has lead to the conclude that Salmonella includes 2 species with replacement of traditional testing with multiple serovars as below molecular testing protocols Salmonella species and subspecies No.of Targets of molecular tests are stable genes or serovars gene products that are unique to Salmonella S.enterica subspecies enterica(I) 1,454 S.enterica subspecies salamae (II) 489 S.enterica subspecies arizonae(IIIa) 94 S.enterica subspecies diarizonae(IIIb) 324 S.enterica subspecies houtenae (IV) 70 S.enterica subspecies indica(VI) 2 S.bongori(V) 20 Total 2.463
10/20/2017 4 Differentiates enteric organisms based on their ability to decarboxylate or deaminate lysine and to form hydrogen sulphide Biochemical Identification • Genetic variability of clinical strains may occur as a result of mutations or plasmid exchange and is of great concern in the clinic - escapes detection in standard assays used in hospitals and industry - sucrose and lactose positive strains acquired genes for this phenotype via plasmids • Bismuth sulfite agar remains a medium of choice due to … - high selectivity - responds effectively to low levels of hydrogen sulfide Biochemical Identification • Variability in biochemical traits has lead to the replacement of traditional testing with molecular testing protocols • Targets of molecular tests are stable genes or gene products that are unique to Salmonella Taxonomy and Nomenclature WHO Collaborating Centre for Reference and Research conclude that Salmonella includes 2 species with multiple serovars as below Salmonella species and subspecies No. of serovars S. enterica subspecies enterica (I) 1,454 S. enterica subspecies salamae (II) 489 S. enterica subspecies arizonae (IIIa) 94 S. enterica subspecies diarizonae (IIIb) 324 S. enterica subspecies houtenae (IV) 70 S. enterica subspecies indica (VI) 12 S. bongori (V) 20 Total 2,463
10/20/2017 Serological Identification Gram-negative cell wall O-polysaccharide Aim:to determine the complete antigenic formulas for individual Salmonella isolates 3 main antigenic determinants 1.O-antigen associated with lipopolysaccharides heat stabile polysaccharide 与A ran Serological Identification 2.H-antigen associated with peritrichous flagella heat-labile protein antigens 3.Vi(virulence)-antigen associated with capsular antigen Weak or no only in serovars Readily agglutinates Typhi,Paratyphi C, with antibodies agglutination with and Dublin antibodies
10/20/2017 5 Serological Identification Aim: to determine the complete antigenic formulas for individual Salmonella isolates 3 main antigenic determinants 1. O-antigen associated with lipopolysaccharides - heat stabile polysaccharide Gram-negative cell wall Readily agglutinates with antibodies Weak or no agglutination with antibodies Serological Identification 2. H-antigen associated with peritrichous flagella - heat- labile protein - may produce 1 or 2 sets of flagellar antigens 3. Vi (virulence)- antigen associated with capsular antigen - only in serovars Typhi, Paratyphi C, and Dublin