Enterobacteriaceae I: E.coli

• gastroenteritis: infections acquired exogenously or from normal microbiome thru plasmids, bacteriophage DNA (transduction)
• non-gastroenteritis (extraintestinal infections): acquired endogenously

• entertoxigenic (ETEC)
• enteroaggregative (EPEC)
• shiga toxin producing (STEC)
• enterohemorrhagic (EHEC)
• enteroinvasive (EIEC)

• STa and STb
• STa leads to increase in cellular cGMP levels and hypersecretion of fluids and reduced absorption of fluids

• LT-I, LT-II, LT-III
• increases cAMP levels causing enhanced secretion of chloride and decreased absorption of sodium chloride

• bacteria attaches to epithelial cells
• contains a cluster of 40 virulence genes in a pathogenicity island called locus of enterocyte effacement (LEE)

40 virulence genes of EPEC that contains T3SS and virulence effector proteins

EPEC adheres to enterocytes by adhesins and pili which forms an actin microfilament pedestal

shiga toxin inhibits host cell protein synthesis that disrupts systemic absorption

• UTI: caused by hemolysin HllyA, adhesins
• neonatal meningitis: caused by K1 capsular antigen e.coli's
• septicemia

• strong lactose fermentation
• antibiotic therapy (resistance to penicillins)
• proper cooking of beef to prevent STEC
• avoiding unnecessary catheters
• high hygienic standards

• strong lactose fermentation
• STEC strains: does not ferment sorbital, direct detection of shiga toxin from feces

intestinal absorptive cell in epithelial lining of gut

lymph follicles beneath the epithelium that interact with antigens in the gut. contains peyer's patch cells

MQ, denderitic cells, B cells, T cells

• microfold cell
• cells above Peyer's Patches that take up antigen from the gut and present them to immune cells

• crosses by M cells or enterocytes. 
• can mimic psuedoappendicitis and cause enterocolitis

• shigella cells do not directly invade enterocytes from gut lumen
• attaches and invades M cells before invading enterocytes

• three ways
• 1. invasion by endocytosis by M cells, then M cells pass the bacteria to macrophages in the Peyer's patch
• 2. bacteria enter enterocytes by endocytosis
• 3. bacteria are directly taken up in the lumen via phagocytosis by dendritic cells that extend projections across the epithelium

phagosome

• pathogenicity island I (PAI I): encodes salmonella secreted invasion protein (SsP) and T3SS I that injects proteins into host cell
• pathogenicity island II (PAI II): encodes genes for invading host immune response and T3SS II

• effects mainly GI tract
• releases prostaglandins
• stimulates cAMP production, resulting in fluid release into gut, causing diarrhea

transported by MQ to the liver, spleen, and bone marrow where they replicate and lead to development of enteric typhoid fever

all animals and humans

• ingestion of contaminated foods
• high inoculum

• ppl that eat contaminated foods
• patients with reduced gastric acid levels

• contaminated foods
• fecal-oral spread in children
• low inoculum

• salmonella typhi 
• salmonella paratyphi

• typhoid fever/ paratyphoid fever
• colonizes gall bladder, may be asymptomatic

• gastroenteritis: non blood diarrhea
• septicemia: seen in s. typhi, paratyphi, and choleraesuis
• enteric fever: s. typhi produces typhoid fever
• asymptomatic colonization in gall bladder (s. typhi and s. paratyphi)

isolation from stool

• antibiotic treatment not recommended for enteritis
• S. typhi and S. paratyphi should be treated with antibiotics
• proper cooking of food
• vaccines

• shigella dysenteriae: produces shiga toxin
• shigella flexneri: infectous in developing countries
• shigella sonnei: infections in developed countries
• shigella boydii: not commonly isolated

• invade inside host cells of the colon
• secrete virulence effector proteins IpaA, IpaB, IpaCm and IpaD by T3SS
• resists phagocytosis by inducing apoptosis

IL-18 which attracts polymorphonuclear leukocytes (PMNs) that destabilize integrity of intestinal wall, allowing for more shigella cells to cross the epithelial barrier and reach deeper tissues

• A-B enterotoxin 
• disrupts protein synthesis by cleaving ribosome
• toxin activity primarily damages epithelium

only humans

• low inoculum
• transmitted person to person, fecal-oral in low sanitary and personal hygiene standards
• occurs mainly in day care centers, nurseries,

• enterocolitis, a pediatric disease
• profuse watery diarrhea
• cramps
• tenesmus (straining to defecate)
• pus and blood in stool
• can progress to severe shigella dysenteriae
• symptoms occur 1-3 days after ingestion

stool

antibiotic therapy

• capsule
• mucoid colonies

• necrotic destruction of alveolar spaces
• cavitation
• production of blood tinged sputum

• granuloma inguinale
• transmitted by sex or nonsexual trauma to genitalia

granulomatous disease of nose

chronic atrophic rhinitis

• UTI
• infections in bladder or kidney
• produces large quantities of urease which increases pH of urine and kidney stones

yes they swarm

• nosocomial infections affecting neonates or immunocompromised pts
• can colonize any body site
• linked to surgical wounds or pts who stay in ICUs

• nosocomial infections
• affecting neonates and immunocompromised patients
• causes meningitis and brain abscess in neonates
• UTI

• nosocomial
• UTI
• wound infections

• nosocomial
• colonizes urinary and respiratory tracts

• immunoassays 
• molecular probes