Chapter 23 Flashcards
Microbial Diseases of the Digestive System (17 cards)
Peptic Ulcers (75)
Signs & Symptoms
Abdominal pain is main symtom
Pathogen & Virulence Factors
HELICOBACTER PYLORI; numerous virulence factors; Flagella enable burrowing through stomach lining; adhesions facilitate attachment to gastric cells; urease neutralizes stomach acid
Epidimiology
Fecal-oral transmission is unlikely; stress may worsen ulcer symptoms
Diagnosis, treatment, and prevention
Diagnosis based on X-ray exam to identify ulcers and presence of H. Pylori in clinical specimens; treated with antimicrobials & drugs that inhibit stomach acid; prevented by avoiding fecal-oral transmission
Bacterial Gastroenteritis (76) (Shigellosis)
Sign & Symptoms
Inflammation of stomach or intestines caused by bacteria; nausea, vomiting, diarrhea, abdominal pain, and cramps; dysentery produces loose, frequent stool containing mucus and blood; Associated w/ contaminated food or water and poor living conditions
Pathogen & Virulence Factors
Caused by 4 species of SHIGELLA; Virulence factor include type III secretion systems and enterotoxins (SHIGA TOXIN)
Pathogenesis and Epidemiology
Pathogen colonizes cells of the small, then large intestine
Diagnosis, treatment, and prevention
Diagnosed by symptoms & presence of Shigella in stool; Supportive treatment & administration of antimicrobials
Bacterial Gastroenteritis: Traveler’s Diarrhea (77)
Pathogen & Virulence Factors:
CAUSED BY ESHERICHIA COLI; VIRULENCE FACTORS; ADHESIONS, FIBRIAE, AND TOXINS
PATHOGENESIS & EPIDEMIOLOGY
Diarrhea mediated by enterotoxins; common in developing countries
Diagnosis, treatment, and prevention
Diagnosis is based on signs & symptoms; Treatment is based on fluid & electrolyte replacement; antidiarrheal drugs prolong the symptoms
Bacterial Gastroenteritis: Campylobacter Diarrhea (78)
Pathogen & Virulence
Caused by CAMPYLOBACTER JEJUNI; Virulence factors: ADHHESIONS, CYTOTOXINS, ENDOTOXINS
Pathogenesis and epidimiology
Virulence factors cause bleeding lesions and inflammation; CHICKENS ARE THE MAIN SOURCE OF HUMAN INFECTIONS
Diagnosis, treatment, and prevention
Diagnosis is based on signs & symptoms; most cases resolve without treatment; prevented with proper hygiene after handling raw poultry
Bacterial Gastroenteritis: C.diff (79) (Antimicrobial-Associated) Diarrhea
Signs & Symptoms
PSEUDOMEMBRANOUSE COLITIS OCCURS IN SEVERE CASES
Pathogen & Virulence factors
CLOSTRIDUM DIFFICILE; Antimicrobial use facilitates overgrowth of C difficile; antimicrobial uses facilitates overgrowth of C. difficile; C. difficile produces two toxins
Pathogenesis:
Toxins mediate inflammation and pseudomembrane formation
Epidemiology
By-product of modern medicine; any antimicrobial can trigger the disease
Diagnosis, treatment, and prevention
Diagnosis is based on presence of bacterial toxin in stool; treated w/antimicrobials; avoid unnecessary use of antimicrobials
Salmonellosis & Typohoid Fever (80)
Pathogen & Virulence Factors
SALMONELLA ENTERICA serotypes; serotypes TYPHI and PARATYPHI cause typhoid fever; serotypes enteritidis and typhimurium cause salmonellosis; bacteria tolerate acidity of stomach & pass to intestine; toxins disrupt numerous cellular activities
Pathogenesis & Epidemiology
Typhoid fever is acquired by contaminated food or water; salmonellosis is often acquired by consuming contaminated eggs
Cholera (81)
Pathogen & Virulence Factors
VIBRIO CHOLERAE; occurs in salt and freshwater; environment within the human body activates some Vibrio genes; Most important virulence factor is production of CHOLERA TOXIN
Pathogenesis & Epidemiology
Pandemics have occurred throughout history
Diagnosis, treatment, and prevention
Diagnosis based on presence of “RICE WATER” STOOL; treated w/supportive care and administration of doxycyline; available vaccine provides only short-lived immunity; proper hygiene is important preventative measure
Bacterial Food Poisoning (intoxication) (82)
Signs & Symptoms
Nausea, vomiting, diarrhea, cramping
Pathogen & Virulence Factors
STAPHYLOCCUS AUREUS; virulence factors include 5 enterotoxins
Pathogenesis & Epidemiology
Outbreaks are associated w/social functions
Diagnosis, treatment, and prevention
Diagnosis is based on signs & symptoms; treated w/fluid & electrolyte replacement; proper hygiene can reduce incidence
Mumps (83)
Caused by mumps virus; humans are the only natural host; Once a very common childhood disease; nearly nonexistent in developed countries because of immunization; no specific treatment for mumps; infected individuals develop lifelong immunity; INFECTS SALIVARY GLANDS; complications include inflammation of testes, meninges, pancreas, and possible deafness
Viral Gastroenteritis (84)
Sign & Symptoms
Similar to those of bacterial gastroenteris; dehydration is common complication
Pathogens and Pathogenesis
Caused by CALICIVIRUSES, ASTROVIRUSES, AND ROTAVIRUSES; these viruses infect cells lining the intestinal tract
Epidemiology
More cases occur in winter; ROTAVIRUSES are important causes of childhood deaths in developing countries
Viral Hepatitis (85)
Signs & Symptoms
Jaundice, abdominal pain, fatigue, vomiting, weight loss; symptoms may occur years after initial infection
Pathogen & Pathogenesis
Liver damage due mostly to host immune response; Pathogens: HEPATITIS A VIRUS (HAV); HEPATITIS B VIRUS (HBV); HEPATITIS C VIRUS (HCV)
Diganosis, treatment, and prevention
VACCINES AVAILABLE AGAINST HAV AND HBV; Alpha interferon and nucleotide analogs help reduce levels of virus (NEW MEDS ARE REPLACING INTERFERON); supportive care for symptoms; prevented with good hygiene and safe sex or abstinence
Giardiasis (86)
Signs & Symptoms
Often asymptomatic; diarrhea & associated symptoms can last up to 4 weeks
Pathogen
Caused by GIARDIA INTESTINALIS; G. Intestinalis cysts are resistant to chlorine, heat, drying, and stomach acid
Epidemiology
Occurs in developed and developing countries; Individuals ingest cysts from contaminated water, food, or hands; hikers, campers, and swimmers are at risk
Diagnosis, treatment, prevention
Diagnosed by microscopic observation of Giardia in stool; treated w/metrondazole for adults, furazolidone in children; prevention relies on good hygience and filtering water in endemic areas
Cryptosporidiosis (87)
Signs & Symptoms
Severe watery diarrhea w/potentially serious complications
Pathogen & Pathogenesis
CRYPTOSPORIDIUM PARVUM; pathogenicity of C. Parvum is unclear
Epidemiology
Infection results from drinking contaminated water
Diagnosis, treatment, and prevention
Presence of oocysts in feces is diagnostic; treated w/fluid and electrolyte replacement; Prevented w/proper hygiene
Amebiasis (88) Protozoan
Signs & Symptoms
Luminal amebiasis is asymptomatic; invasive amebic dysentery causes severe diarrhea, colitis, appendicitis; invasive extraintestinal amebiases causes necrotic lesions in various organs
Pathogen, Virulence factors, and Pathogenesis
Caused by ENTAMOEBA HISTOLYTICA; Virulent strains produce numerous proteins that are toxic to cells and facilitate invasion; Trophozoites in the peritoneal cavity or blood cause symptoms
Epidemiology
Transmitted by consumption of contaminated food or water, from contaminated hands, or oral-anal intercourse; majority of individuals develop luminal amebiases; human carriers help maintain transmission
Diagnosis, treatment, prevention
Diagnosed by microscopic observation of Entamoeba in stool or intestinal biopsy; treated w/oral rehydration therapy and antiamebic drugs; prevent w/proper hygiene, safe sex; Individuals in endemic areas should drink bottled water and avoid uncooked vegetables or unpeeled fruits
Tapeworm Infestations (89) HELMINTHIC INFESTATION
aka CESTODE
Signs & Symptoms
Usually asymptomatic; Nausea, abdominal pain, weight loss, and diarrhea may occur
Pathogens
Taenia Saginata: Beef Tapeworm
Taenia Solium: Pork Tapeworm
Life cycle split between primary & intermediate host
Epidemiology
Taenia species live worldwide where beef & pork are food; High Incidence areas are regions of inadequate sewage treatment; also where humans live in close contact w/livestock
Diagnosis, treatment, prevention
Diagnosed by presence of proglottids in fecal sample; treated w/niclosamid or praziquental; prevention relies on thorough cooking of meals
Pinworm Infestations (90)
Pinworms are nematodes; long, thin, cylindrical helminth
Signs & Symptoms
Perianal itching, irritability, decreased appetite; 1/3 of case are asymptomatic
Pathogen and Infestation
Caused by ENTEROBIUS VERMICULARIS; Females deposit eggs in the perianal region at night; Eggs can be dislodged and spread the disease
Epidemiology
Infections commonly occur in children; Enterobius is the most common parasitic worm US
Diagnosis, treatment, prevention
Diagnosis is based on identification of eggs or adult pinworm; treated w/pyrantel pamoate or mebendazole; prevention requires strict personal hygiene
Anisakiasis (91)
RESULT FORM INFESTATION OF SEVERAL PARASITIC NEMATODES
Signs & Symptoms
Typically asymptomatic; Abdominal pain, nausea, vomiting, and fever may occur; some individuals develop an allergic rash
Pathogen & Infestation
Most commonly caused by Anisakis Simplex; complex life cycle with several larval stages
Epidemiology
20,000 cases occur worldwide
Diagnosis, treatment, prevention
Diagnosis is generally made using endoscopy to visualize worms; treatment involves removing worms from the intestine; prevented by avoiding raw & undercooked marine life
