Enterobacteriaceae

TribeGenus EscherichiaeaeEscherichia Shigella EdwardsielleaeEdwardsiella SalmonelleaeSalmonella CitrobacteriaceaeCitrobacter KlebsielleaeKlebsiella Enterobacter Hafnia Serratia ProteeaeProteus Morganella Providencia YersinieaeYersinia ErwinieaeErwinia

Escherichia E. coli –Theodore Escherich in 1885 – most significant species –common isolate from the colon flora –black/green metallic sheen on EMB –posesses O (Shigella), H and K (Group B N. meningitidis) Ag. –other species: blattae, vulneris, fergusonii, hermanii

Diarrheal Infections * EPEC – enteropathogenic E. coli - infantile diarrhea - watery stool w/ mucus but w/o blood * ETEC – enterotoxigenic E. coli - traveller’s diarrhea - infective dose of produce LT and ST toxin (hypersecretion) - non-bloody, watery diarrhea with abdominal cramps and low grade fever

Diarrheal Infections EIEC – entero invasive E. coli –cause dysentery ( direct penetration, invasion and destruction of the intestinal mucosa) – similar with dysentery –scanty stool with pus, mucus and blood –Sereny test – determines the invasiveness of EIEC (+) result – keratoconjunctivitis in guinea pig

Diarrheal Infections EAEC – enteroadherent E. coli cause diarrhea by adhering to the mucosal surface of intestine. watery diarrhea, vomiting and dehydration EHEC – enterohemorrhagic E. coli or VTEC (E. coli 0157:H7) Hemorrhagic diarrhea, colitis and hemolytic uremic syndrome (HUS) Bloody diarrhea and crampy abdominal pain

E. coli Microscopic Exam

Growth on Eosin Methylene Blue (EMB)

Other Infections Septicemia and Meningitis –accounts for 40% of neonatal meningitis Urinary Tract Infections –90% of cases of UTI

Shigella 4 subgroups Fermentation of lactose mannitol ODCONPG AS. dysenteriae neg negnegneg B S. flexneri neg posnegneg C S. boydii neg posnegneg D S. sonnei neg pospospos

Clinical Infections - Shigella Shigellosis or Bacillary Dysentery –watery diarrhea –bloody stool with WBC’s & mucus –fecal-oral route (human – only known reservoir) –self-limiting but highly communicable bec. of low infective dose (200 bacilli) –Gay bowel syndrome (S. flexneri)

Shigella on CM

Edwardsiella –tarda (human pathogen – bacteremia and wound infection) –hoshinae (snakes, birds and water) –ictaluri (enteric septicemia in fish)

Salmonella –2200 species –3 common species (cholerasuis, typhi, enteritidis) –7 subgroups (with Arizona as groups 3A & 3B) –Virulence factors O, H and Vi antigens

Gram negative rods Do not ferment lactose Produce H 2 S Major cause of food poisoning in the U.S. Cause intestinal infections (enterocolitis); enteric fevers (typhoid fever); and systemic infections (septicemia) Chickens are a major reservoir for this bacteria Identification on basis of antigens (O, H, Vi) Salmonella

Enterocolitis:invasion of epithelial cells of intestines infectious dose (ID50) ~ 100,000 organisms infection of gut - inflammation and diarrhea, self correcting Typhoid:starts in small intestine: enters and multiplies in mononuclear cells; spreads to liver, gallbladder, spleen. Leads to bacteremia with onset of fever. carrier state - organisms excreted in feces Septicemia:minority of infections, usually in patients with underlying disorder Salmonella - pathogenesis

S. enteritidis S. typhi S. typhimurium

Salmonella

Citrobacter resembles Salmonella but are ONPG (+) & LDC (-) Citrobacter species –freundii (UTI, pneumonia, intraabdominal abscess) –diversus (neonatal meningitis) –amalonaticus (extraintestinal infections) C. freundiiS. diversus H2S+- Indole-+ KCN+-

Klebsiella Klebsiella-Enterobacter-Serratia-Hafnia K. pneumoniae >Friedlander’s bacilli (encapsulated and mucoid) > (+) String test K. oxytoca – similar w/ K. pneumoniae except for its indole production K. ozanae – from nasal secretions K. rhinoschleromatis – rhinoscleromatis (infection of nasal cavity with intense swelling and malformation of the entire face and neck)

Klebsiella

Enterobacter –species: habitat: soil, water, dairy products –normal flora of the git of animals & humans –motile, ODC & ONPG (+)

Enterobacter LDCADHODCUreaseYellow pigment E. cloacae-++ V- E. aerogenes E. gergoviae E. sakazakii E. taylorae-++ --

Enterobacter

Serratia –opportunistic pathogens –DNAse, lipase, gelatinase S. marcescens S. liquefaciens S. rubidaea S. oderifera

Serratia

Hafnia Hafnia alvei –2 biotypes H. alvei H. alvei Biotype 1 – associated in breweries –delayed (+) citrate reaction is its major characteristic

Proteus rapid urease producers Swarming, burned chocolate odor P. mirabilisP. vulgaris Indole-+ ODC+- Fermentation –Maltose-+ –Xylose++ –Salicin -+ ChloramphenicolSR

Proteus Proteus mirabilisSwarming pehomenon

Morganella Formerl known as Proteus M. morganii – only specie UTI’s and wound infections

Providencia Providencia ( 4 species – P. alcalifaciens, P. rustigianii) P. rettgeriP. stuartii Urease+- Citrate++

Yersinia 11 species –Y. pestis (plague) – bipolar staining (wayson) Bubonic – bite of infected flea Pneumonic Prefered growth at 25 deg C –Y. enterocolitica (acute enteritis – appendictis like) Pig, cats and dogs Cold enrichment Motile at RT –Y. pseudotuberculosis Pathogen in animals (turkey, geese, doves, farm and domestic animals)

Agent of bubonic plague, pneumonic and septicemic plagues Bubonic plague contracted via flea bites Y. pestis sheds capsule while growing in invertebrate host. In humans most of the microbe is taken up and killed by PMN cells Some organisms taken up by Macrophages which can’t kill pestis. Organism multiples in Mac and resynthesizes capsule Organism kills Mac and is released into extracellular environment. The encapsulated microbe resists phagocytosis and spreads to lymph nodes which become swollen, and hemorrhagic giving the black buboes characteristic of the disease. Microbe rapidly spreads through blood, liver, spleen, lung giving rise to highly contagious pneumonia (highly fatal).

Yersinia Safety pin appearance Yersinia pestis

Erwinia Plant pathogens Fail to grow in CM used in the isolation of enteric bacilli

End of Presentation