MCB Exam 3-E

• Streptococcus mutans
• Anaerobic env allows bacteria to thrive, releasing acid & forming plaque
• VF: dextran (sticky material) and pili allow biofilm formation on tooth

• Tarter trapped at base of teeth triggers, causing receding gums
• VF: proteases brk down gum tissue

• Fecal-oral transmission
• VF: flagella, adhesions, urease & other enzymes
• Acid from stress or eating acidic or spicy food causes small holes in stomach lining where org can get in

Enzyme brks down urea & produces ammonia, producing ammonium hydroxide which raises pH = less acid, causing ulcers

• General term for inflammation of stomach or instestines by drinking or eating bacterial contaminated water, or poor living conditions
• Symptoms: vomiting, diarrhea, abdominal pain
• Dysentery: severe form; loose frequent stool w/mucus & blood

• Attaches to cell surface--> water loss--> watery diarrhea
• Enters cell---> bloody diarrhea & tissue loss
• Passes thru intestinal wall "sub-mucousal" & into blood stream, entering rest of body (passes right thru intestine to go to blood & body)

• Water or raw seafood
• Cells can't absorb water- ions become highly concentrated in intestine, causing water flow in, but water cannot be reabsorbed by intestines
• Most die from dehydration so trmt is fluid replacement

• Fecal-oral
• Goes into cell, stopping protein synthesis, causing tissue loss (shiga-like toxin)

Same as Traveler's Diarrhea

• Leading cause of diarrheal disease in US in summer
• Fecal-oral
• VF: adhesions, cytotoxins, endotoxin
• Diagnosis: not tested for b/c difficult to grow in lab, just give Rx

• Chicken, poultry, eggs
• S&S: typical symptoms w/fever, headache, muscle pain, malaise

• More serious infection by salmonella (one of most serious microbial infection)
• S&S: complications such as intestinal hemorrhage, perforation; Can become systemic, kidney failure; can travel thru intestines & into gallbladder where it can live, becoming a chronic carrier
• If antibiotic isn't finished, can become carrier

• Staphylococcus aureus
• Toxins cross mucous membranes of intestinal tract (doesn't have to be live bacteria)
• Symptoms w/in 4-6 hrs

• Can get from hospital or normal flora; antibiotics allow it to take over
• Susceptibility: mostly children, newborns
• Makes Toxin A&B
• S&S: can cause loss of tight junctions (of cells..pt where 2 cells meet); usually asymptomatic colonization; mild to severe diarrhea
• Can lead to colitis & toxic megacolon

Excessive tissue growth from loss of tight junctions, and colon becomes enlarged

• Excess liver enzymes in blood
• Presence of antibody in blood (ELISA test)

Effect of body trying to protect itself & remove infecton, causing inflammation which damages cells

Effect of virus itself, which damages cells

Fecal-oral, food-borne; sometimes takes several wks to show up so immunization can be effective (not chronic)

Percutaneous, permucosal; blood

• Associated w/liver cancer
• Modes of transmission:
• Sexual
• Parenteral- pierce skin
• Prenatal- mom to child

• 41% heterosexual
• 31% unknown
• 15% injecting drugs

• Chronic, low fatality
• Transmission:
• Percutaneous- drug use; transfusion
• Permucosal- perinatal, sexual

• 44% other high risk/low socioeconomic status
• 38% injecting drugs
• 10% sexual/household

• Giardiasis
• Cryptosporidiosis
• Amebiasis

• Enter via ingestion of infectious cyst
• Esp in hikers
• Incubation: 1-2 wks
• S&S: greasy, frothy, fatty diarrhea w/bad odor, abdominal distention, cramps
• Trmt: Metonidazole (adults), Furazolidone (children)

• Enters via water contamined w/oocysts, also fecal-oral
• Immunocomp ppl at risk for severe disease
• S&S: acute, short-term; severe watery diarrhea w/headache, muscular pain, cramping, nausea, fatigue, life-threatening complications
• Diagnosis: oocysts in stool
• Trmt: supportive

• Enter via ingestion in regions of poor sanitary conditions
• Incubation: 6-20 dys
• S&S:
• Luminal amebiasis- asymptomatic
• Invasive amebic dysentary- severe diarrhea, colitis, appendicitis
• Invasive extraintestinal amebiasis- necrotic lesions on organs
• Trmt: oral rehydration & antiamebic drugs