Micro Chap 22

-if left undisturbed, normal biota biofilm eventually contains anaerobic bacteria that can damage the soft tissues and bones (periodontium) surrounding the teeth
-introduction of carbohydrates to the oral cavity can result in breakdown of dentition

-most common infectious disease of human beings
-symptoms: often not noticeable, but range from minor disruption in the enamel to complete destruction of the enamel and deeper layers
-deeper lesions can result in infection to soft tissue inside the tooth leading to a toothache
-streptococcus mutans, streptococcus sobrinus, others

-97% to 100% of the population has some manifestations of it by age 45
-most are due to bacterial colonization and varying degrees of inflammation

-initial stage:gingivitis (swellings, loss of normal contour, patches of redness, and increased bleeding of the gingival)
-if persists, periodontitis develops
*extension of gingivitis into the periodontal membrane and cementum
*increases the size of pockets b/w the tooth and the gingival and can cause bone resorption enough to loosen and possible lose the tooth

-synergistic infections involving Treponema vincentii, Prevotella intermedia, and Fusobacterium species
-together they produce several invasive factors that cause rapid advancement into the periodontal issues
-severe pain, bleeding, pseudomembrane formation, and necrosis

-incubation period 2 to 3 weeks
-initial symptoms: fever, nasal discharge, muscle pain, and malaise
-may be followed by inflammation of the salivary glands, producing gopherlike swelling of the cheeks (parotitis)
-multiplication in the salivary glands followed by invasive of other organs, especially testes, ovaries, thyroid gland, pancreas, meninges, heart, and kidneys

-Helicobacter pylori thrives in the acidic environment of the stomach and has been linked to a variety of gastrointestinal ailments
1. -sharp or burning pain emanating from the abdomen

-actual lesions in the mucosa of the stomach
2. -lesion in the uppermost portion of the small intestine
-severe can be accompanied by bloody stools, vomiting, or both
-long-term infection with H. pylori might by a contributing factor to stomach cancer

-in the US up to 1/3 of all cases transmitted by contaminated food
-most cases are self-limiting and do not require treatment
-some (E. coli 0157:H7) can be devastating

-can be severe (elevated body temp and septicemia) or mild (vomiting, diarrhea, and mucosal irritation)
-symptoms usually spontaneously subside after 2-5 days

-fever, diarrhea, and abdominalpain
-the bacterium infiltrates the mesenteric lymph nodes and the phagocytes of the liver and spleen
-progressive and invasive that leads eventually to septicemia

-causes the most severe form of dysentary
-uncommon in US
-frequent, watery stools, fever, and intense abdominal pain
-nausea and vomiting are common
-often bloody stools

-most virulent strain
-enterohemorrhagic
-symptoms range from mild gastroenteritis with fever to bloody diarrhea
-about 10% of patients develop hemolytic uremic syndrome (can cause kidney damage and failure)
-can also cause neurological symptoms such as blindness, seizure, and stroke

-acute diarrhea caused by other E. coli (4 categories)

-presentation varies depending on which type of E. coli is causing the disease
-traveler's diarrhea: watery diarrhea, low-grade fever, nausea, and vomitin

-cause a disease similar to Shigella dysentery
-invade gut mucosa and cause widespread destruction
-blood and pus found in stool
-significant fever

-profuse, watery diarrhea
-fever and vomiting also common
-produce effacement of gut surfaces

-can cause chronic diarrhea in young children and in AIDS patients

-most common bacterial cause of diarrhea in the US
-frequent watery stools, fever, vomiting, headaches, and severe abdominal pain
-symptoms may last beyond 2 weeks
-symptoms may subside then recur over a period of weeks
-in a small number of cases, can lead to a serious neuromuscular paralysis called Guillain-Barre syndrome (GBS)

-Y. enterocolitica and Y. pseudotuberculosis
-uncommon in US
-inflammation of the ileum and mesenteric lymph nodes gives rise to severe abdominal pain
-infection occasionally spreads to the bloodstream

-causes pseudomembranous colitis
-major cause of diarrhea in hospitals
-able to superinfect the large intestine when drugs have disrupted the normal biota
-produces two enterotoxins (toxins A and B) that cause areas of necrosis in the wall of the intestine
-diarrhea
-severe cases exhibit abdominal cramps, fever, and leukocytosis

-incubation period of a few hours to a few days
-symptoms begin abruptly with vomiting
-followed by copious watery feces called secretory diarrhea
-can lose up to 1 liter of fluid an hour in severe cases

-headache, sweating, vomiting, severe abdominal cramps, and diarrhea
-in AIDS patients may develop into chronic persistent diarrhea

-effects of infection vary with age, nutritional state, general health, and living conditions of the patient

-many other viruses can cause gastroenteritis
-for example adenoviruses, noroviruses, and astroviruses
-common in the US and around the world
-profuse, water diarrhea of 3-5 days duration

-symptoms in the gut that are caused by a performed toxin of some sort
-if the symptoms are violent and the incubation period is very short, intoxication rather than infection should be considered

-associated with food such as custards, sauces, cream pastries, processed meats, chicken salad, or ham that have been contaminated and then left unrefrigerated for a few hours
-toxins do not noticeably alter the food's taste or smell
-heating the food after toxin production may not prevent disease
-symptoms: cramping, nausea, vomiting, and diarrhea
-rapid recovery-usually within 24 hours

-two exotoxins: one causes diarrheal-type disease, the other cause an emetic disease
-the type of disease that takes place is influences by the type of food that is contaminated
-emetic form frequently linked to fried rice, especially when cooked and kept warm for long periods of time
-diarrheal form associated with cook mats or vegetables that are held at a warm temp for long periods of time

-animal flesh and vegetables such as beans that have not been cooked thoroughly enough to destroy endospores
-acute abdominal pain, diarrhea, and nausea in 8-16 hours
-rapid recovery

-lasting longer than 14 days
-infectious or noninfectious
-AIDS patients suffer from it due to opportunistic infections
-several microbes can be responsible

-adheres to human cells in aggregates rather than as single cells
-stimulates large amounts of mucus in the gut

-incubation periods of about 1 week
-watery diarrhea, stomach cramps, bloating, fever, and muscle aches
-if prolonged, also experience anorexia and weight loss

-diarrhea of long duration, abdominal pain, and flatulence
-stools have a greasy, malodorous quality
-fever usually not present

-clinical amoebiasis exists in intestinal and extraintestinal forms

-cecum, appendix, colon, and rectum
*secretes enzymes that dissolve tissues
*leave erosive ulcerations as it penetrates deeper layer of mucosa
*dysentery, abdominal pain, fever, diarrhea, weight loss
*can also manifest hemorrhage, perforation, appendicitis, and amoebomas

-common target is the liver
*amoebic hepatitis
*rarer complications- pulmonary amoebiasis

-inflammatory disease marked by necrosis of hepatocytes and a mononuclear response that swells and disrupts the liver architecture
-occurs when certain viruses infect the liver
-causes jaundice when bilirubin accumulates in the blood and tissues

-in general, far milder and shorted term than the other forms
-either subclinical or vague, flulike symptoms
-in some cases, may include jaundice and swollen liver
-darkened urine often seen
-not oncogenic
-complete uncomplicated recovery

-may include fever, chills, malaise, anorexia, abdominal discomfort, diarrhea, and nausea
-rashes may appear
-arthritis may occur
-can be serious and life-threatening
-some patients develop glomerulonephritis and arterial inflammation
-complete liver regeneration and restored function occur in most patients
-small number of patients develop chronic liver disease (necrosis or cirrhosis)

-"silent epidemic"
-takes may years to cause noticeable symptoms
-shares many symptoms of HAB but is more likely to become chronic
-cancer may also result

-usually provoke an increase in granular leukocytes called eosinophils (eosinophilia)
-most spend part of their life cycle in the intestinal tract

-localized hemorrhage of the bowel caused by worms burrowing and piercing intestinal mucosa
-heavier infections can cause dysentery, loss of muscle tone, and rectal prolapse

-pronounced anal itching when the mature female emerges from the anus and lays eggs
-can also suffer from disrupted sleep, nausea, abdominal discomfort, and diarrhea

-few symptoms
-occasionally proglottids in stool
-sometimes vague abdominal pain and nausea

-possible abdominal discomfort or nausea
-anemia

-mild symptoms
-most common tapeworm infections in the world

-larvae and adult stages in humans
-releases eggs in feces which are then spread to other humans
-ingested eggs hatch in intestine
-larvae then penetrate intestinal wall, enter the lymphatic and circulatory systems, sweep into the heart, arrive at the capillaries of the lungs
-then larvae migrate up the respiratory tree to the glottis
-worms are swallowed and returned to the small intestine, reach adulthood, and reproduce
-can also invade biliary channels of the liver and gallbladder, and sometime emerge from the nose and mouth
-severe inflammatory reactions mark the migratory route

-larvae hatch outside the body
-infect by penetrating the skin (usually through bare feet)
-actively burrow into the skin, reach the lymphatic or blood circulation, carried to the heart and lungs
-larvae proceed up the bronchi and trachea to the throat
-swallowed and arrive in the small intestine, where they anchor, feed on blood, and mature
-eggs appear in the stool about 6 weeks after the time of entry
-symptoms follow the progress of the worm in the body

-can complete its life cycle either inside the human body or outside in moist cell
-larvae penetrate the skin
-worm enters the circulation, carried to the respiratory tract and swallowed, enters the small intestine to complete development
-eggs are laid in the gut, eggs hatch into larvae in the colon

-Opisthorchis sinensis and Clonorchis sinensis
-Fasciola hepatica

-chinese liver flukes
-complete their sexual development in mammals; intermediate development in snail and fish hosts
-ingest cercariae in inadequately cooked or raw freshwater fish
-larvae hatch and crawl into the bile duct
-mature and shed eggs into the intestinal tract
-feces containing eggs passed into standing water
-eggs infect snails that release cercariae that invade fish
-symptoms are slow but include thickening of the lining of the bile duct and possible granuloma formation in the liver

-occasionally transmitted to humans, common in sheep, cattle, goats, and other mammals
-complex life cycle
-symptoms of vomiting, diarrhea, hepatomegaly, and bile obstruction

-trichinosis
-life cycle spent entirely within the body of a mammalian host
-human eats undercooked pork; cyst envelope digested in the stomach and small intestine, and larvae is liberated
-larvae burrows into the intestinal mucosa and reach adulthood and mate
-larvae then penetrate the intestine and enter the lymphatic channels and blood
-final development occurs when the coiled larvae are encysted in the skeletal muscle
-symptoms may be unnoticeable or life-threatening, depending on how many larvae were ingested
-first symptoms mimic influenza or viral fevers with diarrhea, nausea, abdominal pains, fever, and sweating
-second phase produce puffiness around the eyes, intense muscle and joint pain, shortness of breath, and pronounced eosinophilia

-first symptoms: itchiness in the area where the worm enters the body
-followed by fever, chills, diarrhea, and cough
-chronic infection can lead to hepatomegaly and liver disease and splenomegaly