Digestive System Infections Flashcards
Gastritis
Caused by: Helicobacter pylori (gram- with multiple flagella
Signs and Symptoms: peptic ulcers of stomach, abdominal pain, tenderness, bleeding, stomach cancer
Pathogenesis: survives acidic environment, produces urease which converts urea to ammonia, making alkaline microenvironment, burrow into mucus layer in stomach
Spread by: fecal-oral route, bacteria in well water, flies transmitting from feces
Treatment: antibiotics and acid production inhibition
Herpes Simplex (Cold Sores)
Caused by: Herpes Simplex Viruses (HSV1 - oral, HSV2 - genital, persist as latent viruses)
Signs and Symptoms: fever, small blisters in mouth
Pathogenesis: multiplies in epithelium and destroys cells, persists in nerve cells
Epidemiology: initial infection in childhood, close contact, saliva
Mumps
Caused by: Mumps virus (ssRNA enveloped virus)
Signs and Symptoms: fever, loss of apetite, headache, swelling of parotid glands, meningitis
Pathogenesis: inhaled via saliva droplets, symptoms in 15-21 days, multiplies in parotid glands
Epidemiology: humans only host, one type of virus so lifelong immunity following infection, spread a week before or two weeks after symptoms appear
Cholera
Caused by: Vibrio cholerae (gram- halotolerant, grow in alkaline conditions)
Signs and Symptoms: watery diarrhea, cramps, loss of fluids and electrolytes
Pathogenesis: sensitive to acid, produce cholera toxin encoded by bacteriophage, toxin causes cells to secrete chloride which causes sodium and water to flow out
Spread by: fecally contaminated water, crab, oysters
Shigellosis
Caused by: Shigella species (gram-, S. dysenteriae most virulent, S. sonnei least virulent)
Signs and Symptoms: dysentery, headache, vomiting, fever, stiff neck, convulsions, joint pain
Pathogenesis: antigen sampling of M cells, multiply in macrophages, some produce shiga toxin which causes hemolytic uremic syndrome (HUS)
Spread by: fecal-oral route, small infectious dose, Acid resistant, poor sanitation, food and water contaminated with fecal matter
Gastroenteritis
Caused by: Escheria Coli (gram-, ferment lactose)
Signs and Symptoms: depend on strain, watery diarrhea, dysentery, hemolytic uremic syndrome
Pathogenesis: strains in six pathovars based on virulence factors, STEC colonize large intestine, produce shiga toxin encoded by phage, diarrhea, HUS, can be prevented with bismuth preparations (pepto-bismol)
Spread by: foodborne, ground beef, unpasteurized milk, green leafy vegetables, untreated cow manure, low infectious dose
Treatment: antibiotics not routinely used, need to replace lost fluids, handwashing, pasteurization, cooking food
Salmonella Gastroenteritis
Caused by: Salmonella enterica (gram-, 2400 serotypes based on somatic (O), flagellar (H), and capsular (K) antigens
Signs and Symptoms: diarrhea (sometimes bloody), abdominal cramps, nausea, vomiting, headache, fever, short lived and mild
Pathogenesis: most sensitive to acid, attach to epithelial cells and type III secretion system to induce endocytosis by membrane ruffling
Spread by: mostly nonhuman animal sources, poultry, eggs, tomatoes, alfalfa sprouts, pet reptiles
Typhoid and Paratyphoid Fevers
Caused by: Salmonella serotypes Typhi and Paratyphi
Signs and Symptoms: increasing fever, severe headache, constipation, abdominal pain, intestinal rupture, bleeding, shock, death
Pathogenesis: bacteria coloniza intestines, cross mucous membrane in M cells, multiply in macrophages, destroy peyer’s patches
Spread by: humans, person to person, contaminated food and water, gallbladder (typhoid mary)
Treatment: antibiotics, removal of gallbladder, antibiotic therapy, 2 vaccines
Clostridium difficile Associated Disease (CDAD)
Caused by: Clostridium dificile (gram+, forms endospores, one or more cytotoxins)
Signs and Symptoms: mild diarrhea, fever, pain, colitis, pseudomembranous colitis
Pathogenesis: two toxins (A and B) and cause pseudomembranes to form
Epidemiology: primarily seen in patients on antibiotic therapy, acquired in hospitals, endospores in feces
Treatment: stop antibiotics to end symptoms
