Week 11 & 12 Chapter 19: Enterobacteriaceae PDF

Chapter 19 Enterobacteriaceae Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 1  General Characteristics  Enterics All ferment glucose All reduce nitrate to nitrites All are oxidase negative Except Plesiomonas Motility All motile...

Chapter 19 Enterobacteriaceae Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 1  General Characteristics  Enterics All ferment glucose All reduce nitrate to nitrites All are oxidase negative Except Plesiomonas Motility All motile at body temperature except  Klebsiella  Shigella  Yersinia Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 2 Key Characteristics of the Family Enterobacteriaceae Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 3  Colony Morphology  Gram-negative coccobacilli or straight rods Not very useful in identification other than ruling out other organisms  Facultatively anaerobic Thioglycolate broth: growth throughout the tube  Macroscopic morphology Large moist, gray colonies Some mucoid Klebsiella Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 4  Growth on Media  MacConkey (MAC) agar Selective and differential Bile salts and crystal violet inhibit gram positive Lactose fermentation is differential.  Eosin-methylene blue (EMB) agar Selective and differential Methylene blue inhibits gram positive Lactose and sucrose fermentation is differential. Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 5  Growth on Media (Cont.)  Hektoen enteric (HE) agar Selective and differential Bile salts inhibit gram-positive, some gram- negative Lactose and sucrose fermentation is differential. Most nonpathogens ferment lactose and sucrose show orange color (low pH) Pathogens (salmonella and shigella) green to blue green color with H2S gas creating a black ppt Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 6  Growth on Media (Cont.)  Xylose lysine deoxycholate (XLD) agar Selective (less so than MAC and HE) and differential Sodium desoxycholate Inhibits gram-positive, some gram-negative Three carbohydrates, sucrose and lactose in excess, and xylose with a phenol red indicator Lysine present to detect lysine decarboxylation Thiosulfate present to detect hydrogen sulfide (H2S) Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 7  Growth on Media (Cont.)  XLD agar Yellow colonies Fermenters or those not producing lysine decarboxylase Escherichia coli, Citrobacter Colorless or red colonies Shigella Red colonies with black centers Initially yellow then revert to red  When lysine is decarboxylated, causing alkaline pH – Salmonella Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 8 Classification of the Family Enterobacteriaceae Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 9 Biochemical Characteristics of Tribes of Enterobacteriaceae Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 10  Virulence and Antigenic Factors  Adherence: prevent being removed from tissue  Toxins: food poisoning  Invasive enzymes: spreading factors  Antibiotic resistance Extended spectrum β-Lactamases (ESBL)  Serology O antigen (somatic antigen) Heat stable antigen located in the cell wall (LPS) H antigen Flagellar antigen; heat stable K antigen Capsular antigen; heat labile K1 antigen of E. coli, Vi antigen of Salmonella typhi Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 11  Clinical Significance  Two major types Opportunistic pathogens Normal flora Infections in other “non-normal” sites  Septicemia, wounds, urinary tract infections (UTIs), meningitis  E. coli Primary pathogens Salmonella spp. Shigella spp. Yersinia spp.  Generally from ingesting contaminated food and water Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 12 Bacterial Species and the Infections They Commonly Produce Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 13  E. coli  Dry pink colonies on MAC plates  β-hemolysis on blood agar plate (BAP)  Motile  Sex pili, fimbriae  Possess O, H, K antigens Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 14  E. coli (Cont.)  Biochemical reactions Fermentation of glucose, lactose, trehalose, and xylose Indole production from tryptophanase Glucose fermentation via mixed acid pathway Methyl red (MR) positive Does not produce H2S, DNase, urease, or PAD Citrate negative Indole; MR; Voges-Proskauer (VP); citrate: IMVC Positive; positive; negative; negative Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 15 Colonies Growth of E. coli Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 16 Features of Pathogenic E. coli Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 17  Clinical Types of E. coli  Uropathogenic E. coli Most common cause of UTIs in humans Pili allow attachment to epithelium. Cytolysins can kill immune cells and inhibit phagocytosis. Aerobactin allows bacteria to chelate iron. Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 18  Clinical Types of E. coli (Cont.)  Gastrointestinal pathogens  Five major categories Enterotoxigenic (ETEC) Enteroinvasive (EIEC) Enteropathogenic (EPEC) Enterohemorrhagic (EHEC) Enteroadherent Diffusely adherent (DAEC) Enteroaggregative (EAEC) Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 19  Clinical Types of E. coli (Cont.)  ETEC Diarrhea in infants and adults in tropics and subtropics Traveler’s diarrhea (requires large inoculum 106- 1010) lasts 1 to 5 days Contaminated food and drink Colonize the small intestine but adhesive fimbriae Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 20  Clinical Types of E. coli (Cont.)  ETEC (Cont.) Release toxins Heat labile toxin (LT): A and B subunits; B binds GM1 ganglioside receptor, and A acts on adenyl cyclase, converting adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP), which leads to hypersecretion of fluids. Heat-stable toxin (ST) stimulates guanylate cyclase, increasing cyclic guanosine monophosphate (cGMP), leading to hypersecretion. Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 21  Clinical Types of E. coli (Cont.)  EPEC Infantile diarrhea children less than 1 year Nurseries and daycares Due to adhesions  Symptoms Low-grade fever Malaise Vomiting Diarrhea Large amounts of mucus without apparent blood Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 22  Clinical Types of E. coli (Cont.)  EIEC Affects adults and children Rare in the United States Dysentery with direct penetration, invasion, and destruction of intestinal mucosa Very similar to shigellae (coming up soon) but require higher amounts of inoculum Watery diarrhea with scant stool, pus, mucus, and blood Nonmotile and do not ferment lactose (thus very similar to shigellae) Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 23  Clinical Types of E. coli (Cont.)  EHEC Hemorrhagic diarrhea, colitis Hemolytic-uremic syndrome (HUS) Low platelets, hemolytic anemia, kidney failure Watery diarrhea progressing to bloody diarrhea without pus Can be fatal  Young children and elderly Undercooked meats, unpasteurized milk, apple cider Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 24  Clinical Types of E. coli (Cont.)  E. coli O157:H7 Toxins produced by Shiga toxigenic E. coli (STEC) Verotoxin I (phage mediated) cytotoxin  Damages Vero cells (African green monkey kidney cells)  Also known as Shiga toxin (Stx)  Toxin neutralized by Shiga toxin antibodies Verotoxin II  Not neutralized by Shiga toxin antibodies  Can screen O:157H7 E. coli on sorbitol- containing MAC (SMAC) plate Does not ferment sorbitol and is MUG negative  Now emergent phenotype is sorbitol fermenting and nonmotile (O157:NM) Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 25  Clinical Types of E. coli (Cont.)  Diagnosing Identifying serotype and comparing to known Shiga toxin–producing strains Screening stool filtrates for toxin Demonstrate a fourfold increase in toxin- neutralizing antibody titer Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 26  Clinical Types of E. coli (Cont.)  Enteroadherent E. coli Two types  DAEC UTIs Diarrhea Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 27  Clinical Types of E. coli (Cont.)  EAEC Adheres to the surface of the small intestine Watery diarrhea with symptoms lasting more than 2 weeks Commensals from colon with special adherence adaptations for UTIs Described from culture with Hep2 cells causing aggregative “stacked-brick” pattern Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 28 Extraintestinal Infections of E. coli  Septicemia and meningitis Most common in neonates and very young children Gain infection just before or during delivery, and when infections involve the amniotic fluid Capsule antigen K1 Predisposition for meningitis Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 29  Other Escherichia Species  Escherichia hermanii Yellow-pigmented Isolated from cerebrospinal fluid (CSF), wounds, and blood Isolated from foodstuffs such as raw milk and beef Clinical significance still not fully established  E. vulneris Newest member Wound infections Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 30 Comparison of E. hermanii and E. vulneris Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 31 Klebsiella, Enterobacter, Serratia, Pantoea, Cronobacter, and Hafnia  Tribe Klebsielleae  Opportunistic and nosocomial infections  Characteristics Simmon’s citrate positive Potassium cyanide broth negative No H2S production No deamination of phenylalanine Generally urease negative Indole negative (usually); MR negative VP positive Thus IMVC: negative; negative; positive; positive Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 32  Klebsiella Species  K. pneumoniae Most common isolate Particularly if gram-negative rods in lower respiratory tract infection of hospitalized patients Also wound, UTIs, liver abscesses, and bacteremia  Increase resistance, including carbapenemase Moist gray mucoid colonies Virulence factor Polysaccharide capsule  Prevents phagocytosis and some antimicrobials Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 33 Differentiating Klebsiella Species Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 34 Colonies of K. pneumoniae Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 35  Klebsiella Species (Cont.)  K. oxytoca Similar to K. pneumoniae except indole positive Affects similar sites  K. ozaenae Isolated from nasal secretions and cerebral abscesses Plasmid-mediated ESBLs  K. pneumoniae subspecies rhinoscleromatis Rhinoscleroma Intense swelling and malformation of the entire face and neck Africa and South America Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 36  Raoutella Species  R. ornithinolytica Indole and ornithine decarboxylase positive  R. planticola Both species found in urine, respiratory tracts, and blood Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 37  Enterobacter Species  E. cloacae  E. aerogenes Two above are most common  E. gergoviae Respiratory samples, rarely blood  E. hormaechei Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 38  Enterobacter Species (Cont.)  Citrate positive, potassium cyanide broth positive  MR negative, VP positive  Usually produce ornithine decarboxylase Lysine decarboxylase produce by most (not E. cloacae or E. gergoviae)  Infection sites Wound Urine Blood CSF Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 39 Diagnostic Features of Select Enterobacter Species Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 40  Pantoea and Cronobacter Species  Pantoea agglomerans Formerly Enterobacter agglomerans Similar to Klebsiella pneumoniae, so need to differentiate Primarily a plant pathogen  Cronobacter sakazakii Meningitis and bacteremia in neonates from powdered infant formula Also brain abscesses, respiratory, and wound infections Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 41 Photograph of P. agglomerans Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 42 Photograph of C. sakazakii Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 43  Serratia Species  Serratia species Positive ONPG (slow lactose) Exception is S. fonticola DNase Highly resistant to antimicrobials S. marcescens Prodigiosin: red pigment when growing at room temp Usually most clinically relevant Nosocomial infections of the urinary tract, respiratory tract, bacteremia Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 44  Serratia Species (Cont.)  S. liquefaciens  S. rubidaea Red pigment when growing at room temp  S. odorifera Dirty, musty odor Two biogroups Biogroup 1: respiratory  Positive for sucrose, raffinose, ornithine, and indole (60%) Biogroup 2: blood and CSF  Negative for sucrose, raffinose, ornithine; positive for indole (50%) Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 45  Serratia Species (Cont.)  S. plymuthica Red pigment when growing at room temp  S. ficaria  S. entomophila  S. fonticola Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 46 Colonies of Serratia Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 47  Hafnia  H. alvei Linked to gastroenteritis Delayed citrate reaction  H. alvei biotype 1 Grows in beer wort Has not been isolated clinically Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 48  Proteus Species  P. mirabilis and P. vulgaris P. mirabilis most commonly isolated Isolated from urine, wounds, ear, and blood infections Separate this tribe by positive phenylalanine deaminase Generally produce swarming on laboratory media Burnt chocolate odor Lactose negative and produce urease Produce H2S Occasional exceptions for P. vulgaris Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 49  Proteus Species (Cont.)  P. mirabilis Indole negative; ornithine decarboxylase positive  P. vulgaris Indole positive; ornithine decarboxylase negative Sucrose fermentation = A/A with H2S on triple sugar iron (TSI) Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 50 Swarming Proteus Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 51  Morganella Species  M. morganii UTI infections Possible agent of diarrhea Similar to Proteus Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 52  Providencia Species  Five species Two major pathogens P. alcalifaciens may also be a pathogen.  P. rettgeri Urinary tract pathogen Occasionally nosocomial outbreaks  P. stuartii Nosocomial burn unit outbreaks Also isolated in urine cultures No swarming  Both have high resistance to antimicrobials. Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 53  Differentiating Characteristics of Proteus, Providencia, and Morganella Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 54  Edwardsiella  E. tarda is only pathogen Urea negative Lysine decarboxylase positive H2S positive Indole positive No growth on citrate  Bacteremia and wound infections Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 55  Erwinia and Pectobacterium  Plant pathogens Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 56  Citrobacter Species  11 species  C. freundii Most common Nosocomial UTIs, pneumonias, endocarditis in drug abusers, and intra-abdominal abscesses  C. koseri (diversus) Nursery outbreaks of neonatal meningitis and brain abscesses  C. braakii Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 57  Citrobacter Species (Cont.)  Identifying Citrobacter Weak urease activity Ferment lactose Grow on Simmon’s citrate MR positive  Similar to Salmonella C. freundii: most hydrolyze urea but do not decarboxylate lysine Salmonella: most do not hydrolyze urea and most decarboxylate lysine Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 58 PART II WEEK 12 Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 59 Primary Intestinal Pathogens of the Family Enterobacteriaceae Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 60  Salmonella Species  Gram-negative rods, facultatively anaerobic  Clear, colorless, non–lactose-fermenting colonies with black centers Negative for indole Negative for VP Negative for phenylalanine deaminase Negative for urease Most produce H2S Exception: Salmonella paratyphi A No growth in potassium cyanide Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 61  S. enterica  Six subspecies in S. enterica  S. typhi, S. choleraesuis, S. paratyphi Differentiating Salmonella subgroups and members Lysine decarboxylase rules out S. paratyphi. Ornithine decarboxylase rules out S. typhi. Trehalose fermentation rules out S. choleraesuis. Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 62 Biochemical Differentiation of Select Salmonella Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 63  S. enterica (Cont.)  Virulence factors Fimbriae required for adhesion to intestine Ability to traverse intestinal mucosa Enterotoxin involved in gastroenteritis Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 64  Antigenic Structures  O and H antigens  H antigen Antigens occur in phases (Phase I and Phase II). Phase I antigens are not always present, but if they are they can identify a particular serotype. Phase II are nonspecific.  Capsular antigen Vi similar to K capsule antigen Prevents phagocytosis Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 65 Antigenic Structures of Salmonellae Used in Serologic Typing Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 66  Clinical Infections  Acute gastroenteritis or food poisoning with vomiting and diarrhea Caused by organism (colony-forming units [CFUs] of 106 organisms), not really by toxin Poultry, milk, eggs, egg products, and pet handling Recently other foods such as peanut butter, cantaloupe, cereals, dog food, and tomatoes  Can develop into a carrier state and pass to others Organisms are in gallbladder  Nontyphoidal bacteremia Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 67  Clinical Infections (Cont.)  Typhoid fever Caused by S. typhi  Other enteric fevers S. paratyphi S. choleraesuis Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 68  Typhoid Fever Disease Course  Ingestion of organism  Development of fever, malaise, anorexia, lethargy, myalgia, and a dull headache Looks like the flu  Reach the small intestine, invade and penetrate the intestinal mucosa Leads to constipation  Enter the lymphatic system and are sustained in mesenteric lymph nodes Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 69  Typhoid Fever Disease Course (Cont.)  Seed the bloodstream Spread to spleen, liver, and bone marrow Engulfed by monocytes and grow intracellularly  Rereleased into the blood stream Prolonged bacteremia “Rose spots” in the periumbilical region Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 70  Typhoid Fever Disease Course (Cont.)  Invasion of the gallbladder and Peyer’s patches; release of bacteria into the bowel via the biliary duct Gallbladder is the foci in long-term infections. Severe infections can cause necrosis of gallbladder and/or Peyer’s patches. Hemorrhage and perforation of the bowel Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 71 Culture and Serologic Diagnosis of Typhoid Fever Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 72  Clinical Infections (Cont.)  Nontyphoidal bacteremia Prolonged fever with intermittent bacteremia Two groups Young children  Fever and gastroenteritis with brief episodes of bacteremia Adults  Transient bacteremia during episodes of gastroenteritis or develop symptoms of septicemia without gastroenteritis Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 73  Characteristics of Shigella Species  Nonmotile  Generally do not produce gas from glucose Except some types of S. flexneri  No urease production  No H2S in TSI  No decarboxylation of lysine  Cannot utilize acetate or mucate as carbon source  S. sonnei is positive for ONPG and ornithine decarboxylase.  S. flexneri is negative for these tests. Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 74 Colonies of S. sonnei Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 75  Antigenic Structures  O antigens separated by serologic grouping  K antigens Must be removed to type O antigen Heat labile  Lack H antigens Nonmotile Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 76  Shigella Species  S. dysenteriae (group A) Most serious infection (developing countries)  S. flexneri (group B) Second most common isolate in the United States Associated in men who have sex with men and in young adults ~25 years old  S. boydii (group C) More common in developing countries  S. sonnei (group D) Most common isolate in the United States Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 77  Biochemical and Serologic Differentiation of Shigella Species Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 78  Clinical Infection of Shigella  Dysentery Local inflammation, fever, chills, shedding of intestinal lining, mucus, blood, ulcer formation, tenesmus (possible rectal prolapse) S. dysenteriae (most severe)  Usually nonfatal and self-limiting in developed countries Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 79  Clinical Infection of Shigella (Cont.)  Low inoculum: 10 to 200 organisms cause disease Spread by fecal-oral route or by flies Higher risk Day care centers, crowded populations, anal-oral sex Children under 10 and infants under 1 are particularly susceptible.  Infection results from penetration of the mucosal epithelium. Production of Shiga toxin produces some of the symptoms. Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 80  Yersinia Species  Y. pestis Plague Bubonic, septicemic, and pneumonic forms Transmitted through bite of infected fleas Pneumonic plague through respiratory droplets Gram-negative coccobacilli resembling a safety pin appearance (bipolar staining) Preferential growth at 25°to 30°C Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 81  Yersinia Species (Cont.)  Y. enterocolita Acquired from contact with swine, cats, dogs Ingestion of contaminated food that contacted fecal material Refrigeration is ineffective because it survives in cold temperatures. Symptoms Acute gastroenteritis, simulating appendicitis Arthritis Erythema nodosum  Tender red nodules with itching and burning on lower legs (shins) Primarily affects children between 1 to 5 years and adults with underlying diseases Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 82  Yersinia Species (Cont.)  Y. pseudotuberculosis Rodents, farm animals, birds Causes caseous swellings called psuedotubercles in mesenteric lymph nodes Ingestion of fecal material Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 83  Differentiating Yersinia Species  Cefsulodin, irgasan, novobiocin (CIN) agar and Yersinia-selective agar (YSA) help isolate Yersinia species Now CIN II, which can also isolate Aeromonas  Y. pestis Negative for motility above 22°C Negative for ornithine decarboxylase  Y. enterocolitica Positive for motility at 25°C (room temperature) Positive for ornithine decarboxylase  Y. pseudotuberculosis Positive for motility at 25°C (room temperature) Negative for ornithine decarboxylase Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 84 Differentiation Within the Genus Yersinia Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 85  New Genera of Enterobacteriaceae  Budivicia  Buttiauxella  Cedecea  Ewingella  Kluyvera  Leclercia  Leminorella Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 86  New Genera of Enterobacteriaceae (Cont.)  Moellerella  Obesumbacterium  Photorhabdus  Rahnella  Tatumella  Trabulsiella  Yokenella Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 87  Kluyvera Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 88  Laboratory Diagnosis of Enterobacteriaceae  Specimen collection and transport  Isolation and identification Direct microscopic examination Not very helpful in differentiating species Culture Generally grow quickly and easily Identification  Screening stool cultures for pathogens Separate pathogens from normal flora Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 89 Lysine Iron Agar (LIA) and TSI Screening Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 90  Hektoen Enteric and Xylose Lysine Deoxycholate (XLD) Agar Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 91 CHROMagar™ Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 92  Identification  Determine if Enterobacteriaceae Gram-negative Oxidase negative Except for Plesiomonas shigelloides Always use young colonies from sheep blood agar (SBA) plates Ferment glucose Reduce nitrate to nitrite Except Photorhabdus and Xenorhabdus Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 93 Schematic Diagram for Enterics Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 94 Differentiating Characteristics of Enterobacteriaceae Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 95 Differentiating Characteristics of Enterobacteriaceae (Cont.) Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 96 Differentiating Characteristics of Enterobacteriaceae (Cont.) Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 97 Differentiating Characteristics of Enterobacteriaceae (Cont.) Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 98  Serologic Grouping  Serologic grouping Salmonella 60 types of O antigens  95% are serogroups A through E1 Direct or latex agglutination tests for serogroup Shigella A through D serogroups Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 99 THE END Copyright © 2015 by Saunders, an imprint of Elsevier Inc. 100