Cholerae, E Coli, Shigella, Salmonella

Gram - (Pt 2)

Curved, motile, NaCl, stomach, antacids

Vibrio genus

• __ rod bacillus, non spore-forming, highly __ with polar flagella

• Grows in broad temperature range and requires __(halophilic)

• Susceptible to __ acids - survives well at pH 8-9.5

  • __ that reduce gastric acid production can increase susceptibility

Pili, A, polysaccharides, disseminated, cholera, A-B

Vibrio genus

• __ are important attachment factors

• LPS with lipid _ (endotoxin) and O-___

• May produce a polysaccharide capsule important for __ infections

• Main virulence factor is __ Toxin (__ exotoxin)

Pathogenicity island, ADP, alpha, cAMP, H2O

Vibrio cholerae Cholera Toxin (A-B exotoxin)

• Cholera toxin gene: Acquired as __ __ via lysogenic infection by bacteriophage CTX

• Cholera Toxin is __ ribosylating toxin → targets __ G protein subunit → affects membrane-associated adenylyl cyclase

  • Permanent activation of enzyme increases __

  • Hypersecretion of K+, Na+, Cl-, AND __ from cell

Estuary, marine, end, epid, food, water, sanitation

• Vibrio C. species is naturally present in __ or__ environments, endemic along gulf coast

  • __emic and __emics in low-income countries (i.e. Haiti)

  • Transmission via contaminated __ and __, poor __

Inoculum, pili, cholera

Vibrio C. pathogenesis

• Large __/collection is required to bypass stomach acid (barrier to infection)

• Colonizes epithelial cells of small intestine, attachment via __

• Virulent strains secrete __ toxin, propagating disease

Cholera

GI disease with severe water/fluid loss

Asymptomatic, self, 2-3, re-hydration, electrolyte

Cholera

• Majority of individuals have __ infection or __-limited diarrhea

• Incubation period of _-_ days, with abrupt onset

• Tx is __-__ (oral, IV fluids) and __ replacement

Cholera Sx

Dehydration, diarrhea, muscle cramps, metabolic acidosis, hypokalemia, hypovolemic shock, possible cardiac arrhythmias and renal failure

Sanitation, endemic, vaccines, live attenuated

Prevention of cholera

• __ infrastructure to provide clean water and safe food for population

• Traveling to __ region - Have treated/bottled water, handwash, hygiene

• Short-term __ available for travelers

  • Vaxchora: __ __ vaccine effective up to 3 months against cholera

Bacilli, opportunistic, UTIs, endotoxic

Enterobacteriaceae genus

• __ shape; Frequently from animals, but some pathogens strictly human

• Normal microbiome is source of __ infection → particularly __ and diarrhea

• Bacteria from any source entering blood → __ shock

O, K, H

Serotype variants

• _ antigens: Different cell wall (LPS) polysaccharides

• _ antigens: Different capsule polysaccharides

• _ antigens: Different proteins in flagella

Genital, perineum, LPS, capsule, flagella, O, K, H

Escherichia Coli

• Widely found in nature and part of normal microbiota of skin (__ area and __)

• Cell wall with __ endotoxin, has polysaccharide __

• Motility via __

• _, _, _ antigens are most commonly used to identify E coli (has largest variety of serotypes)

Common pili, P pili

Virulence factor pili for E coli

• __ __ help E coli in attaching to many epithelial cell types

• Specialized _ __help E coli bind to kidney cells and erythrocytes, lead to UTIs

Shiga toxin (Stx)

A-B toxin that inhibits protein synthesis in enterocytes (exotoxin of E coli)

Labile Toxin (LT)

A-B toxin similar to Cholera toxin; hypersecretion of ions (exotoxin of E coli)

Heat-Stable Toxin (ST)

Small peptide that interferes with G protein signaling (exotoxin of E coli)

Uropathogenic (UPEC)

Virulence factors of E coli leading to UTIs

Meningitis, birth canal, amniotic

Opportunistic E coli can lead to __ in neonates

• Infection occurs during passage via __ __, OR in utero if ruptured __ membrane

Enterotoxigenic E coli (ETEC)

Produce enterotoxins (LT or ST)

Water, pili, invasion, inflammation, A, infants, traveler’s, fever, A-B

Enterotoxigenic E coli (ETEC)

• Lead to __ loss from enterocytes

• __ mediate adhesion to intestinal mucosa

• No __ or __ of intestinal mucosa

• Some immunity (Ig_) induced after infection

• Major cause of diarrhea in __, __ diarrhea, diarrhea w/o __

• LT and ST exotoxins are __ toxins

Enteropathogenic E coli (EPEC)

Disrupt intestinal enterocyte cells (via specialized pili)

Specialized, attaching and effacing, malabsorption, watery, fever, fecal-oral

Enteropathogenic E coli (EPEC)

• Specialized pili allow cluster formation to enterocyte surface

• __ and __ (A/E) lesions: Loss of microvilli and formation of “pedestals” with bacteria on top, result of bacterial virulence factors

  • Consequences are __ of nutrients from GI tract

• Sx - __ diarrhea, vomiting, and __

• Major cause of diarrheal disease in infants, spread __-__ or fomites

Enterohemorrhagic E coli (EHEC)

Pathogenic and produce exotoxin (Stx)

A/E, Stx, ground beef, hemolytic uremic syndrome, children

Enterohemorrhagic E coli (EHEC)

• Can cause __ lesions and or produce __ exotoxin

• Results from consumption of contaminated __ __, unpasteurized juices

• Sequelae is __ __ __, Life-threatening complication in young __ following E coli GI infection

Vessels, endothelial, RBC, renal, bloody, hyper, edema

Hemolytic Uremic Syndrome (HUS)

• From EHEC

• Pathology - Damage to blood __, __ lining, __ lysis, destruction of platelets, __ failure

• Sx - __ diarrhea, decreased urination, __tension, __

Enteroaggregative E coli (EAEC)

Pathogenic and form a biofilm

2+, HUS, adherence, A/E, biofilm, cytokine

Enteroaggregative E coli (EAEC)

• Infection for __ weeks diarrhea, possible blood in stool, abd pain, vomiting

• Risk associated with __; primarily at risk are infants and children

• __ pili attach to intestinal mucosa but do NOT form _/_ lesions

• DO form a __ coating intestinal mucosa

  • Induce local inflammatory response → __ release

E coli, O, K, human, infectious, sanitation

Shigella genus

• Shigella genus is a subtype of __ __ (bacteria)

• No flagella, DO have _ and _ antigens

• Strict __ pathogens, no infection of animals

  • Transmission is person-person or contaminated food/water

• Most common cause of infectious __

• Low infectious dose that spreads rapidly if __ is poor

Stomach, colon, phagocytosis, actin, immune, apoptosis, shiga

Shigella pathogenesis

• Resistant to __ acid

• Invade and replicate in cells lining __ - destruction of mucosa

• Enter cells via __ and escape vacuole into cytoplasm

  • Rearrange __ filaments in host cells and move thru cytoplasm to adjacent cells → __ evasion

• Induce __ in phagocytic cells

• S dysenteriae species produces __ toxin (Stx)

Epidemic, self, HUS

Shigella pathology and incidence

• __ outbreaks in daycare, nurseries, care facilities often targeting children younger than 10 years

• Incubation of shigella is 1-3 days; Generally __-limited

• Can result in __ (rare sequelae of severe bacillary dysentery) via Stx toxin

O, K, H, amphibians, mammals, S. enterica serotype typhi, food

Salmonella Enterica

• Identified by serotypes _, _, _ antigens

• Most Salmonella serotypes infect wide variety of hosts - __ and __ = natural reservoir

• Salmonella typhi (__ __ __ __) is strictly human pathogen

• Most common __ sources - Poultry, eggs, and dairy products prepared on contaminated food surfaces, or improper food handling

Small, M, invasive, cytoplasm, inflammatory, local

Salmonella pathogenesis

• Passes into __ intestine and attach to _ cells and enterocytes

  • Disrupt function of cells lining GI tract

  • NOT __ to enterocytes

• Also cross __ and enter submucosa → Induce __ response

• Innate immune response controls infections and usually remains __

Salmonella Symptoms

Nausea, vomiting, non-bloody diarrhea, abdominal cramps, headache

Enteritis, 1-2, bacteremia, internal, rinse

Salmonella

• Primary manifestation is gastro__

• Sx start _-_ days after eating contaminated food, last up to 2-7 days

• __ risk higher in pediatric and geriatric patients, immunocompromised

•  General prevention = Cook food to safe __ temperature, buy pasteurized dairy products, __ produce before eating

Salmonella enteric serotype typhi

Typhoid fever is caused by Salmonella typhi (the name)

Macrophages, bacteremia, GI tract, LPS

S typhi survives in __ and is transported to other organs - lymph nodes, spleen, liver, bone marrow

• Multiplies and infects new macrophages in these sites leading to eventual __

• Infection no longer limited to __ __ may NOT produce diarrhea

• Bacteremia may lead to __-induced endotoxic shock

Symptoms of typhoid fever

Fever and headache followed by faint rash “rose spots”

Sanitation, attenuated, polysaccharide

Prevention of typhoid

• Improved __ and personal hygiene practices

• Live__ and __ vaccines available