microbiology 24 - 27

peristalsis

pushes food throughout body

upper digestive system

• mouth (salivary glands)

• the esophagus

• the stomach

lower digestive system

• small intestine

• large intestine

• pancreas

• liver

dysbiosis

imbalance of microorganisms caused by antibiotics that may lead to diarrhea

diarrheal diseases symptoms

fever, nausea, diarrhea

diarrheal diseases pathogenesis

• attach to small and large intestines

• cause localized inflammatory reactions

• transmitted by fecal-oral route

diarrheal diseases treatment

• fatal dehydration can occur if fluids are not replaced

• sewage treatment, handwashing, chlorination of drinking water, proper food prep

gastroenteritis “stomach flu” causative agent

multiple microbes (some bacteria some viruses)

gastroenteritis “stomach flu” pathogenesis

• infectious dose of microbes survive stomach acid (acid tolerant)

• enterotoxins cause loss of water and electrolytes

• cytotoxins cause cell death

electrolytes

minerals like Na, K, Ca, Cl, Mg

gastroenteritis “stomach flu” epidemiology

• hundreds of thousands of children die around the world due to diarrheal illnesses

• infants and children, elderly, immunocompromised most at risk for death

gastroenteritis “stomach flu” treatment and prevention

• oral rehydration therapy (ORT) - glucose and electrolytes

• antibiotics often prolong bacterial infection as they suppress normal microbiota

periodontal disease symptoms

• gingivitis - gums are tender, and bleed easily

• periodontitis - bad breath, gums bleed easily, loosening of teeth

periodontal disease causative agent

bacteria

periodontal disease pathogenesis

• plaque accumulates

• inflammatory response

• membrane attaching root to bone weakens

periodontal disease epidemiology

• almost 70% after 65

• tobacco users, those with immunodeficiency can have severe cases

periodontal disease treatment and prevention

• SRPs

• minor surgery

• antibiotics

• regular flossing and brushing

cholera symptoms

• severe watery diarrhea

• dehydration can lead to organ failure and death

cholera causative agent

bacteria (V. cholerae)

cholera pathogenesis

• large numbers must be ingested

• produce toxins

cholera epidemiology

common worldwide

cholera treatment and prevention

• travelers to some countries should avoid fruit and ice

• vaccines

Escherichia coli gastroenteritis signs and symptoms

• dysentery - blood with diahrrea

Escherichia coli gastroenteritis causative agent

bacteria (E. coli)

Escherichia coli gastroenteritis pathogenesis

toxins lead to cell death

Escherichia coli gastroenteritis epidemiology

epidemics have involved ground beef, unpasteurized milk, contaminated vegetables

Escherichia coli gastroenteritis treatment and prevention

• most cases self-limiting (resolved without Tx)

• pasteurization, cooking food thoroughly, 165 degrees

salmonella gastroenteritis signs and symptoms

stomach cramps

salmonella gastroenteritis causative agent

bacteria (S. enterica)

salmonella gastroenteritis pathogenesis

sensitive to stomach acid, high infectious dose

salmonella gastroenteritis epidemiology

• most cases from animal sources

• can survive for months in soil and water

• poultry eggs are often contaminated

• pet reptiles can infect

salmonella treatment and prevention

• most recover without antibiotics, and many strains of antibiotic-resistant

• sanitary handling of food, cooking to 165 degrees

clostridium difficile infection (CDI) signs and symptoms

• serious cases progress to colitis - colon inflammation

• severe cases are life-threatening

clostridium difficile infection (CDI) causative agent

• bacteria (C. difficlie) (C. Diff)

• forms endospores highly resistant to disinfectants

• many strains

• resistant to antibiotics

• CDC considers C. diff an URGENT HEALTH THREAT

clostridium difficile infection (CDI) pathogenesis

dysbiosis due to antibiotic use allows the proliferation of C. diff

C. diff epidemiology

• primarily in patients on antibiotic therapy

• HAI

• infectious endospores shed in feces

c. diff treatment and preventions

• if possible; stop antibiotics, symptoms often disappear later

• prevention measures such as handwashing, wearing gloves, and disinfection

• fecal microbiota transplant repairs dysbiosis

rotavirus/ norovirus signs and symptoms

abrupt vomiting and profuse watery diarrhea

rotavirus/norovirus pathogenesis

viral protein acts as enterotoxin

rotavirus / norovirus epidemiology

• childhood epidemics

• traveler’s diarrhea

• highly contagious, infectious dose low

• virions resist destruction, stable in the environment

• epidemics common on cruise ships, dormitories, daycare

• more than 50% of foodborne disease outbreaks due to norovirus

rotavirus / norovirus treatment and prevention

• rotavirus vaccine

• NO norovirus vaccine

• hand sanitizers do not inactivate norovirus

• infected food workers should stay home 48 hours after symptoms subside

hepatitis (liver inflammation)

• there are at least five different unrelated viruses that can cause hepatitis, an inflammation of the liver

• three types (A,B, and C) account for most cases

• jaundice (yellowing of skin and whites of eyes) is most noticeable sign

• patients should avoid alcohol and other chemicals that damage the liver

Hepatitis A signs and symptoms

• acute illness

• jaundice, fever, fatigue, clay-colored feces, and vomiting

• children may be asymptomatic

• about one in five adults requires hospitalization

Hepatitis A causative agent

Hepatitis A virus (HAV)

hepatitis A pathogenesis

• virus ingestion then reaches liver

• eliminated in feces

Hepatitis A epidemiology

• spread via contaminated hands, food, or water

• many outbreaks traced to restaurants

• raw shellfish may be source (contaminated water)

• high-risk groups: children in day-care centers, nursing home residents, international travelers

• HAV can spread widely through the population before the detection

• infants, children can shed virus in feces for several months

hepatitis A treatment and prevention

• no antiviral treatment is available

• post-exposure prophylaxis (PEP) can prevent diseases if given within 2 weeks of exposure

• vaccine

hepatitis B signs and symptoms

• acute form ranges from asymptomatic to severe

• can be chronic

• 1 in 5 develop cirrhosis (scarring of the liver), liver failure, liver cancer, or other chronic liver disease

hepatitis B causative agent

• hepatitis B virus (HBV)

• resistant; virus infectious after a week outside the body

hepatitis B pathogenesis

• bloodstream carries to liver

• liver damage likely from cell-mediated immune response

hepatitis B epidemiology

• transmitted in body fluids (saliva, blood, blood products, semen)

• sharing needles, unprotected sex, mother to baby at birth

  • more than 90% of infants infected around birth develop chronic infection

hepatitis B treatment and prevention

• no curative treatment

• vaccine - 3 doses

necrotizing periodontal disease signs and symptoms

bleeding and painful gums with necrotic lesions

necrotizing periodontal disease causative agent

bacteria (spirochete bacteria)

necrotizing periodontal disease pathogenesis

plaque always being present

necrotizing periodontal disease epidemiology

• poor oral hygiene

• poor nutrition

• tobacco use

• immunodeficiency

• substance abuse

necrotizing periodontal disease treatment and prevention

• hydrogen peroxide

• antibiotics

• removing plaque

• daily brushing and flossing; prophy’s 2x a year at minimum

H. Pylori Gastritis signs and symptoms

• most infectious asymptomatic

• gastritis can result in belching, loss of appetite, and nausea

• localized abdominal pain

H. Pylori Gastritis causative agent

bacteria (H. pylori)

H. Pylori Gastritis pathogenesis

• H. Pylori survives acidic environment of stomach

• avoids recognition by immune system receptors

• infections persist for years, often for life

• 90% of those with stomach cancer are infected

H. Pylori Gastritis epidemiology

• half of the world’s population is thought to be infected with H. pylori

• likely transmitted via fecal-oral route

• bacteria found in well water

H. Pylori Gastritis treatment and prevention

antibiotics plus medication to inhibit acid production

Oral herpes simplex signs and symptoms

• small blisters in the mouth or on the lips

• painful ulcers

• can recur

• can be transmitted to infants

Oral herpes simplex causative agent

virus (herpes simplex viruses)

Oral herpes simplex pathogenesis

• viral DNA persists in nerve cells in latent form

• can infect any tissue

  • stress can reactivate

Oral herpes simplex epidemiology

• distributed worldwide

• 1 in 3 Americans infected

• transmitted by close contact

Oral herpes simplex treatment and prevention

• antivirals

• sunlight can trigger, so sunscreens useful as preventive

mumps signs and symptoms

• fever, loss of appetite, headache

• painful swelling of one or both parotoid glands (makes saliva)

• spasm of underlying muscle makes talking and chewing hard

• stiff neck (meningitis)

• pregnant women often miscarry

• sudden onset- deafness

• symptoms generally more severe past onset of puberty

mumps causative agent

virus

mumps pathogenesis

virus inhales via saliva droplets

mumps epidemiology

virus can spread from asymptomatic infections

mumps treatment and prevention

• no effective treatment

• MMR vaccination

poliomyelitis signs and symptoms

• up to 90% of cases are asymptomatic

• In some cases, infection spreads to the CNS

• Weak muscles and loss of function

• in severe cases, respiratory muscles are paralyzed (diaphragm)

• ventilator must be used

poliomyelitis causative agent

viruses (polioviruses)

poliomyelitis pathogenesis

• fecal- oral route

• most people do not develop CNS issues

• a single case of poliomyelitis means that the virus is widespread

poliomyelitis epidemiology

• in endemic areas (disease-present communities), infected newborns are protected by maternal antibodies

• if infected later in life, paralytic disease is more likely to result

• number of cases has recently been increasing

poliomyelitis treatment and prevention

• supportive care, ventilator

• virus inactivated by pasteurization, chlorination

• vaccine

rabies signs and symptoms

• symptoms begin 2 to 3 months after infection with fever, muscle aches, sore throat, fatigue

• paresthesia (tingling) at site of viral entry, usually animal bite

• spread to CNS resulting in confusion, hallucinations, seizures

• later stages in two forms

  • encephalitic and paralytic

paresthesia

tingling

encephalitic rabies

increased salivation and difficulty in swallowing, causing “frothing at the mouth”

paralytic rabies

paralysis, muscle weakness

rabies causative agent

• virus, rabies virus

• replication of virus in brain tissue results in formation of inclusion bodies

rabies pathogenesis

• multiplies in cells at the site of infection

• travels to the spinal cord and brain

• encephalitis (infection of the brain)

rabies epidemiology

• transmission via saliva from the bite of rabid animals

• the main reservoir in the United States is wild animals

• 1-3 cases per year

• about 50,000 to 70,000 deaths worldwide

• most from dog bites

rabies treatment and prevention

• wash the wound with soap and water, then apply antiseptic

• if the animal might is rapid, the person receives post-exposure prophylaxis (PEP)

• four injections of rabies vaccine to provoke immune response

• no effective treatment once symptoms appear

cryptococcal meningoencephalitis signs and symptoms

• difficulty thinking, dizziness, headache

• after weeks or months, vomiting, weight loss, paralysis, seizures, and coma may appear

cryptococcal meningoencephalitis causative agent

• fungus, cryptococcus neoformans (yeast)

cryptococcal meningoencephalitis pathogenesis

• inhaled into lungs

• goes from blood to CNS

cryptococcal meningoencephalitis epidemiology

• worldwide distribution of C. neoformans in soil, vegetation contaminated with bird droppings

cryptococcal meningoencephalitis treatment and prevention

• antifungals

• approximately 70% success

toxoplasmosis signs and symptoms

• usually asymptomatic in healthy individuals

• life-threatening in immunodeficient

• can occur as reactivation of latent infection

• encephalitis with confusion, seizures, paralysis

• may develop brain masses

• fetal ___ can be acquired across the placenta if contracted during pregnancy

• most severe during first trimester; miscarriage, birth defects

toxoplasmosis causative agent

• toxoplasma gondii

• the definitive host is cats

• cysts released in feces of infected cat

  • remain viable for up to a year

toxoplasmosis causative agent

organism enters by ingestion of cysts

toxoplasmosis epidemiology

• worldwide distribution

• contamination of hands, and vegetables can occur when gardening in areas with cats that defecate in the soil

• litter box transmission

toxoplasmosis treatment and prevention

• not treated in otherwise healthy people

• if the fetus is infected, medications

• wash hands after touching raw meat, soil, and cat litter, cook meat thoroughly, and wash fruits and vegetables.

spongiform encephalopathy signs and symptoms

• anxiety, insomnia, fear

• progress to muscle jerks, memory loss, dementia

• incubation period may last years

• once symptoms appear, death generally occurs within a year

spongiform encephalopathy causative agent

prion (misfolded protein)

spongiform encephalopathy epidemiology

• has been transmitted by corneal transplants, surgical instruments, injections of human hormone

• can be transmitted to humans through the consumption of contaminated beef

• rare in humans (<1 case per million people)

• one type (CJD) possibly genetic

spongiform encephalopathy treatment and prevention

• no treatment - prions cannot be destroyed

• always fatal

Hansen’s disease (leprosy) signs and symptoms

• paresthesia - numbness or tingling in hands, feet

• loss of sensation