Lecture 4: Infection and Infectious Diseases

Question 1

Toxins and Infection

Answer 1

An infection is a disease caused by microorganisms invading the body.

Some of these microorganisms release toxins that invade and damage body tissues that also cause injury.

Question 2

Sources of Infection

Answer 2

1. Endogenous: from a source within the body, a normally existing microbe (like an already existing yeast)
2. Exogenous: from a source outside the body, usually a pathogen from the environment (like the flu from the influenza virus)

Question 3

Sources of Infection:

Answer 3

Viruses: a pathogen made of a nucleic acid inside a protein shell

Bacteria: a unicellular organism, no nucleus or organelles

Protozoa: a unicellular, animal like microorganism, not usually harmful to humans

Fungi: yeasts or molds

Helminths: worms

Mycobacteria: type of bacteria with fungi like properties

Prions: a small particle that is made of protein and is infectious

Question 4

line of defence

Answer 4

1. First line of defence:

mechanical barriers-integrity of epithelial surfaces

I. Intact skin and mucous membranes

    II. Oil and perspiration on skin

    III. Cilia in respiratory tract

   IV. Gag and coughing reflex

    V. Peristalsis of the GI tract

    VI. Flushing action of tears, saliva and mucous

    VII. Presence of normal flora in the gut

2. Second line of defence: inflammation, non specific
3. Third line of defence:

acquired immune response or adaptive immunity. Includes the lymphatic system with leukocytes and antibodies including chemicals, proteins and enzymes that aid in an immune response.

Question 5

Spread of infection within host

Answer 5

1. Incubation period: time between entry of the microorganism into the body and the appearance of clinical signs, there are not enough of the organism in the body to produce clinical effects
2. Prodromal period: non specific or generalized symptoms such as fatigue, loss of appetite or headache
3. Acute period: typical symptoms of the infection begin usually caused by damaged tissues

Question 6

Virulence:

Answer 6

The number of organisms and the time they take to start the infection process in a new host.

Question 7

Transmission:

Answer 7

1. Leaving the infected source:

The invading organism must be transmitted from the infected source to the susceptible host.

The infected source portals of exit include:

Feces, urine, vomit, tears, semen, open lesions, blood, saliva.

2. Many possible routes;

Contact: direct or indirect (through a fomite) a fomaite is a contaminate object

Airborne: smaller particles float on air currents for hours when we sneeze

Droplet: larger particles fall within 1 metre of source

Vehicle: common source like food or water

Vector: carried by something else like an insect (mosquito)

Question 8

Nosocomial Infection:

Answer 8

Acquired in a healthcare setting like a hospital or care home.

eg/ clostridium difficile, staphylococcus

Question 9

What makes a host susceptible?

Answer 9

Lack of sleep
Age
Nutritional status
Hygiene
Concurrent disease
Hormonal balance or imbalance (cortisol)
Drug use

Question 10

Patterns of infection:

Answer 10

The invasive microorganism may produce local damage
eg/ welt, wart

The invasive microorganism may produce a toxin that is poisonous to the host
eg/ botulism

The invasive microorganism may produce no local damage but has widespread systemic effects
eg/ HIV

Question 11

Spread of Infection

Answer 11

Directly: some pathogens produce enzymes that damage cell membranes, enabling them to move from cell to cell rapidly

Via natural channels: some pathogens move through membranes (meninges, pleura, peritoneum) and vessels (lymphatic, blood)

Via nerves or phagocytes: eg/ herpes virus

Question 12

Mode of Action:

Answer 12

this explains how the pathogen produces a pathological process.

Viruses: invade cells and interfere with the cell’s metabolism, growth and replication processes

Other organisms: cause the cell to die

Question 13

Reservoir:

Carrier:

Fomite:

Answer 13

Reservoir: a host or person who has a contagious disease

Carrier: a host or person who has a contagious disease, but does not develop the illness

Fomite: an inanimate object that can transmit an infectious disease
eg/ keyboard, doorknob, phone

Question 14

Factors affecting occurrence and spread of infection

Pathogenic factors:

Answer 14

Virulence: measures the power or degree of pathogenicity

Dose: increased numbers are more potent

Site of infection: some sites are more easily infected than others

Synergism between and among different pathogens: they can help each other

Question 15

Host factors that affect spread:

Answer 15

Resistance to infection

	Immune competency

        Low leukocyte count

	Necrosis and ischemic tissue

Question 16

Opportunistic Infection:

Answer 16

Results from an impaired immune system that can not defend against pathogens that are normally found in the environment.

eg/ AIDS or HIV patients, transplant patients, older age, newborns, malnourishment, burn victims or any chronic disease.

Question 17

Clinical Signs and Symptoms

Answer 17

Systemic: fever, chills, lymph node enlargement, malaise

Skin (integumentary system): pus, rash, red streaks, bleeding, open wound

Cardiovascular system: tachycardia, hypotension

Respiratory System: tachypnea, cough, dyspnea, hoarseness, sore throat, nasal drainage, decreased exercise tolerance

Central Nervous System (CNS): confusion, altered level of consciousness, convulsions, headache, photophobia, stiff neck

Gastrointestinal System: nausea, vomiting, diarrhea

Urinary tract: dysuria, flank pain, hematuria, oliguria, urgency, frequency, nocturia

Question 18

Fungal Infection:

Histoplasmosis

Answer 18

Causes a a type of lung infection if histoplasma capsulatum fungal spores are inhaled. Found in soil and bird and bat droppings.

Question 19

Lyme Disease: BB

bacterial Borrelia Burgdorfer

Answer 19

Definition or description:

Lyme disease, after Lyme, Connecticut where it was first discovered in 1975, a disease carried by the deer tick (vector), may affect multi systems in the body such as arthritis (knees & hips), skin, heart and the nervous system. Highest incidence rates in children.

Etiology (cause): borrelia burgdorferi, a spirochete and a bacteria. Is injected into the body by a tick bite from the deer tick (blacklegged tick). Ticks live in bushes, grasses and in wooded areas, most active in summer.

Pathogenesis: tick bites inject pathogen directly into the bloodstream of mammals

Clinical Features:

A skin lesion called a “bull’s eye” rash appears within 3-30 days of bite. Initial symptoms are “flu like”, including nausea, vomiting, fever and chills. Also neurological and arthritic type symptoms come later, complicated with muscle weakness, incoordination, paralysis and encephalitis.

Only 50% of patients testing positive for the bacteria become ill.

Treatment: antibiotics

Massage Considerations:

1. postpone if widespread inflammation is present
2. inquire about symptoms each visit and adjust plan accordingly
3. tailor massage to the individual recent symtoms
4. avoid skin lesions
5. avoid red, swollen joints
6. passive stretching and gentle joint mobilization to tolerance

Question 20

Sexually Transmitted Diseases or Infections: S

Bacterial Syphilis

Answer 20

• Definition or description:

a sexually transmitted bacterial infection transmitted by contact with infected body fluids like semen, vaginal secretions or blood, or with contact with an open skin lesion. May also be spread through a trans-placental route while pregnant. It is estimated that during the 19th century 15% of the whole world’s population had syphilis.

Occurance rates in Canada from 2010 to 2015 incidence has increased by 86%.

If untreated may proceed through four distinctive stages:

1. Primary: primary lesion appears at initial site of infection, called a chancre, which heals in 1-2 months, infection spreads throughout the body
2. Secondary: begins 6 weeks after chancre appears, widespread infection, signs of systemic infection disappear once the immune system has suppressed the infection, takes 2 weeks
3. Latent: if suppression is successful, this dormant stage may last one year or a lifetime
4. Tertiary: most severe stage, formation of gummas (tumour like growths) in the liver, bones, cardiovascular and neurological (causing neurosyphilis) systems. These gummas are fibrotic and necrotic so cause much damage to local tissues.

Etiology (cause): a spirochete shaped bacterium called treponema pallidum

Pathogenesis: the bacterium treponema pallidum invades and causes tissues to fibrose and to die causing necrosis, this tissue forms “gummas” which act like tumours, growing and taking resources. It invades sensitive tissue causing many systemic symptoms.

• Clinical Features:

1. Primary stage: formation of painless, contagious lesion called a chancre at the site of infection (usually genitalia) 3 weeks after exposure. Regional lymph nodes are enlarged and non tender
2. Second stage: 6 weeks after appearance of chancre, widespread rash on skin and mucous membranes. Systemic infection symptoms like low-grade fever, fatigue, lack of appetite, headache, sore throat, and generalized lymph node enlargement (lymphadenopathy). Symptoms disappear within 2-10 weeks
3. Latent stage: asymptomatic, may have skin rashes may recur
4. Tertiary stage: symptoms related to cardiovascular and neurological systems. Causing weakness in blood vessels (stroke, aneurysm), valvular problems, muscular discoordination, visual and auditory impairment, and dementia

• Treatment:

Antibiotics and abstinence or the use of condoms is recommended until treatment is complete. All sexual partners must also receive antibiotics.

Question 21

Infectious Disease: H

Viral Herpes Virus

Answer 21

Family of DNA viruses that cause infections

Virus hides in dorsal root ganglia of the spinal cord and appears when the body is stressed.

5 Different ones:

1. Herpes simplex 1 (oral lesions)

    2. Herpes simplex 2 (genital lesions)

    3. Varicella-Zoster virus (shingles)

    4. Epstein-Barr virus

    5. Cytomegalovirus

Question 22

1. Herpes Simplex 1- oral

Answer 22

Definition or description: Herpes Simplex Type I, estimated 3.7 billion infections
Etiology (cause): herpes virus
Pathogenesis: man is only natural host, spread by contact like kissing, affects skin or mucous membranes, is stored in the dorsal root ganglion for a lifetime and activates when the body is stressed (latent).
Clinical Features: often asymptomatic, most common causes of “cold sores” or oral lesions (painful blisters), easily transmitted via direct or indirect contact or with bodily fluids, vesicles form into shallow sensitive ulcers
Treatment: no treatment, anti viral meds, prevention

Question 23

2. Herpes Simplex 2 - Genital Herpes

Answer 23

• Definition or description:

Herpes Simplex Type 2, estimated 491 million workwide infections, sexually transmitted via genital, oral or anal contact, or via placenta during birth, life long infection, a chronic viral infection that is incurable with outbreaks and remissions. Outbreaks may be attributed to physical, hormonal, immunological stressors like menstruation, stress or sun exposure.

• Etiology (cause):

herpes virus type 2, may rarely come from type 1

Clinical Features: often asymptomatic, causes genital blister-like sores that are often painful, these blisters heal over and crust within 7-10 days. Easily transmitted via direct or indirect contact or with bodily fluids, transmitted from mother to child during birth (transplacentally), may have systemic infection symptoms also like fever, fatigue, lack of appetite, enlarged lymph glands, and muscle aches. Women may have vaginal discharge, and both men and women may experience painful urination (dysuria). Symptoms are more severe in women than in men

• Treatment: no treatment, no cure, anti-viral medications may help, prevention

Question 24

Varicella:
Zoster Virus ( Shingles)

Answer 24

• Definition or description:

this virus causes chickenpox, after the chicken pox has run its course, the virus lays dormant in the peripheral nervous system in the dorsal root ganglia of a spinal nerve where it stays latent until activated by stress, usually later in life. It causes a very painful rash along a sensory nerves dermatome usually on the torso, sometimes on the face.

• Etiology (cause): varicella-zoster virus

Pathogenesis: (chicken pox) inhalation of infected droplets or contact with infected skin

• Clinical Features:

usually unilateral pain, burning, numbness or tingling along a nerve, often on the torso like a stripe. A red rash appears soon after with fluid filled blisters that break open and crust over, very itchy. It persists in the peripheral nervous system as a latent infection and be reactivated later in life as “shingles” also called herpes zoster. Fever, headache and sensitivity to light are rarer symptoms. It may also lead to encephalitis or pneumonia. More common in the elderly due to a weakened immune system.

• Treatment:

vaccination, if infected = lifelong immunity, antiviral medications, pain killers

Question 25

Infectious Disease: C

Viral Cytomegalovirus

Answer 25

• Description: usually asymptomatic, lifetime infection, spread by sexual and non sexual contact with body secretions.
  Etiology: cytomegalovirus
• Pathogenesis: produces symptoms only if the viral load is high enough or immunocompromised, may affect any organ as it is transmitted via the bloodstream.
• Clinical Features: usually silent, asymptomatic, may affect immunocompromised, if symptomatic similar to mononucleosis, if maternal infection may cause congenital defects in developing embryo.
• Treatment: if mild, usually non treated, if serious, antiviral drugs.

Question 26

Genital Warts:

Human Papillomavirus (HPV)

Answer 26

• Definition or description:

a sexually transmitted virus causing skin lesions. Lesions are soft and clustered into groups often in the genitalia, perineal or perianal regions. May also develop in the mouth or throat. Pregnancy increases growth and spread and may be spread to baby from pregnant mom during delivery. May lead to cervical cancer. Most common sexually transmitted disease. Estimated 70% of all sexually active adults are carriers.

• Etiology (cause):

human papillomavirus (HPV) causes genital warts and may also cause warts located on other parts of the body.

• Pathogenesis:

this virus enters healthy epithelial cells infecting their DNA, the newly infected viral cells reproduce uncontrollably and form warts.
Clinical Features: skin lesions located in genital regions, usually painless, but may be numerous and cluster so may uncomfortable.

• Treatment:

as a virus there is no cure, may be surgically removed if cumbersome, but often recurs.

Question 27

Infectious Disease: E

Viral Enteroviruses

Answer 27

• Description:

part of the picornavirus family, affects millions, affects the gastrointestinal tract and may also cause respiratory or nervous system infections. These viruses are moderately contagious by spreading through direct contact with mucus, saliva or feces from an infected person. Examples of enteroviruses: aseptic meningitis, acute paralysis, hand foot and mouth disease, myocarditis, mild respiratory illness, conjunctivitis and poliomyelitis.

• Etiology: enterovirus.
• Pathogenesis: shed in oral secretions, stool, blood, cerebral spinal fluid (CSF) and nasal secretions, enterovirus enters through the mouth via fecal-oral route, it replicates in submucosal tissues of the gastrointestinal tract (peyer’s patches), they migrate to different systems and damage tissues.
• Clinical Features:

symptoms may range from mild to severe, flu like symptoms: fatigue, malaise, fever, chills, appetite loss. Rash/blisters occurs in hands. Motor neuron damage and muscle weakness lead to paralysis in poliomyelitis.

• Treatment:

There is no treatment, medications for symptom relief (exception: polio and hepatitis have vaccines)

Question 28

Infectious Disease: P

Viral Poliomyelitis

Answer 28

• Description:

poliomyelitis also known as “polio”, once ingested travels to the anterior horn of the spinal cord, multiplies and damages motor neurons causing muscle weakness and flaccid paralysis.

• Etiology: poliovirus
• Pathogenesis: virus is ingested and invades lymph tissue then enters the bloodstream and travels throughout the body, it especially gathers and multiplies in the anterior horn of the spinal cord and in motor neurons causing cell destruction with neurological symptoms and damage to the muscle.
• Clinical Features: flu like symptoms: fatigue, malaise, fever, chills, appetite loss. Rash or blisters occur in hand, foot and mouth disease. Muscle weakness that may lead to paralysis.
• Treatment: vaccinations!

Question 29

Infectious Disease: I

Viral Influenza Virus

Answer 29

• Description: the “flu”, acute, contagious infection of the upper respiratory tract, it can also extend into the lower respiratory tract. Usually resolves on its own. With elderly and immunocompromised there is high risk for complications. This virus has many different strains, in two subtypes: influenza A and influenza B and are constantly mutating.
• Etiology: influenza virus, transmitted by infected droplets or touching fomites then touching mouth or nose. Incubation period is 1-3 days and usually lasts 7-10 days.
• Pathogenesis: inside the respiratory tract, the virus attaches to and replicates in the epithelial cell on the lining. This leads to an immune response to the infection causing inflammation and destruction of epithelial cells.
• Clinical Features: fever, chills, cough, sneezing, headache, inflamed respiratory mucosa, nasal discharge, malaise, muscle aches and fatigue. Mortality in high risk patients (elderly or immunocompromised) due to secondary pneumonia infection.
• Treatment: vaccine, bed rest, fluids, symptom management, antiviral medications if severe.

Question 30

Infectious Disease: R

Viral Rhinovirus

Answer 30

• Description:

the “common cold” or upper respiratory tract infection causing inflammation especially in the mucosa of the nose and throat. This virus has over 200 strains that are spread through airborne droplets or from fomites. It is highly contagious, often leads to ear, sinus or lung infections.

• Etiology: rhinovirus
• Pathogenesis: unclear, virus attacks the upper and lower respiratory tracts and attaches to and replicates in the epithelial cell on the lining. This leads to an immune response to the infection causing inflammation and destruction of epithelial cells.
• Clinical Features: acute, afebrile, self limiting, upper respiratory tract symptoms-runny nose, cough and sore throat,coughing, sneezing, watery eyes, nasal congestion and thick yellow discharge, headache, sore throat, and hoarseness. Symptoms begin within 3 days after exposure. Once symptoms begin, it will clear up in 5 days.
• Treatment: bed rest, fluids, medications for symptoms, (decongestants, antihistamines, analgesics).

Question 31

Fungal: P

Fungal Pneumonia (pneumocystis carinii)

Answer 31

• Description: this type of fungus causes a diffuse type of pneumonia, it occurs in the immunocompromised (cancer patients, organ transplant receipients, HIV/Aids or on immunosupressive medications) and in infants making it an opportunistic infection. It is commonly found in the lungs of healthy people with no symptoms.
• Etiology: fungus called pneumocystis carinii
• Pathogenesis: this fungus attaches to the alveolar walls and replicates causing inflammation, an immune response, dysfunction and destruction of the alveoli for oxygenation.
• Clinical Features: fever, non-productive cough, shortness of breath, weight loss and night sweats. No sputum unless the patient has an additional bacterial infection. Rarely may invade liver, spleen, and kidney).
• Treatment: : Anti pneumocystic medication with steroids for inflammation

Question 32

Fungal:

Yeast Infection (Candidiasis)

Answer 32

• Description: yeast infection, candida albican is normal in our GI tract, mouth, genital areas and on our skin. This infection is an overgrowth of candida that causes symptoms. There are many types depending on location:

1. Urinary Yeast infection: candida overgrowth in the urinary tract
2. Genital Yeast infection: in the vagina
3. Oral Thrush: in the mouth
4. Mucocutaneous Candidiasis: on the skin and mucous membranes
5. Etiology: candida albicans, antibiotic use

• Pathogenesis: imbalance of candida causing pathology
  Clinical Features: mouth: yellow or white patches on the tongue and roof of mouth, redness and pain around mouth and throat, cracking in corners, genital: itchiness in vagina, redness, swelling, pain and burning upon urination, painful intercourse and thick white discharge. Urinary system: mild itching, dysuria, watery discharge, skin and mucous membranes: red, itchy rash in the moist folds of skin.

Question 33

Types of Bacteria

Answer 33

1. Cocci: shaped like small spheres
2. Diplococci: in pairs
3. Staphylococci: in bunches
4. Streptococci: in linear groups
5. Bacilli: shaped like rods
6. Spirochetes: shaped like spirals
7. Gram positive: when stained, the cell wall is visible
8. Gram negative: when stained, the cell wall is not visible
9. Chlamydiae: primitive bacteria, no cell walls, lives inside cells, requiring them to divide and survive.
10. Rickettsiae: have cell walls, lives inside cells, requiring them to divide and survive.
11. Mycoplasma: primitive bacteria, no cell walls, very small

Question 34

Infectious Disease:

Pyogenic Bacterial Infection: SA

Staphylococcus Aureus

Answer 34

• Description:

also called “staph”, very common, resides on the skin, over 30 subtypes, most common subtype: staphylococcus aureus, causes many diseases from mild to asymptomatic to severe and fatal (osteomyelitis, respiratory tract infections, infectious arthritis, septicemia, endocarditis, toxic shock syndrome, food poisoning, skin infections). Leading cause of nosocomial and community acquired infections, extremely virulent, nonmotile, anaerobic, very hardy-able to survive on fomites for an extended period of time, may infect blood, skin, lungs, soft tissues, joints & bones. Risk factors: diabetes, chronic illness, HIV, elderly, newborns, malnourished, burn victims and the use of prosthetics.

• Etiology: overgrowth of a bacteria called staphylococcus aureus. This bacteria lives on the skin and in mucosal tissues normally. If bacteria enter bloodstream, joints, bones, lungs or heart can be life threatening.
• Pathogenesis: this opportunistic pathogen overcomes the skin barrier and enters the body and bloodstream, it produces a toxin and proteins that inactivate antibodies and multiplies and stimulates inflammation.
• Clinical Features: may affect blood (septicemia or sepsis), skin (boils, impetigo, cellulitis), lungs, soft tissues, joints and bones (osteomyelitis, infectious arthritis), respiratory infections, endocarditis, toxic shock syndrome, food poisoning, skin infections (abscess, boil). Affected area may be red, swollen and painful with drainage of pus. When Staph is in the blood (sepsis) it causes high fevers, chills and low blood pressure.
• Treatment: antibiotics (penicillin), drainage of pus, good prognosis.
  The emergence of antibiotic-resistant forms of pathogenic S. aureus (e.g. MRSA-Methicillin Resistant Staphylococcus Aureus) is alarming, as there is no other treatment.

Question 35

Infectious Disease:

Pyogenic Bacterial Infection;

Streptococcus

Answer 35

Description: bacterial infection causing many common pathologies.
Streptococcus are divided into two groups:Q know which one in what group

Group A: streptococcus pyogenes
Most common, causes many diseases (streptococcal pharyngitis or strep throat followed by rheumatic fever, cellulitis, erysipelas, impetigo and necrotizing fasciitis). Can be suppurative (pus) or non-suppurative. Transmission is via contact, droplets or food borne.

Group B: streptococcus agalactiae (part of normal gut flora, may spread elsewhere)

Leading cause of neonatal pneumonia, meningitis and sepsis so pregnant women are screened.

• Etiology:

Group A

1. Strep throat or pharyngitis: throat can become red and swollen, white patches on the back of the throat, suggesting the presence of pus, fever, also swollen, tender lymph nodes are present.
2. Impetigo: causes red sores near the nose or mouth which soon break, leaking pus.
3. Rheumatic fever: inflammation of the large joints and heart muscle, fever and joint pain.
4. Necrotizing Fasciitis or flesh-eating disease: intense pain that may seem excessive given the external appearance of the skin. With progression of the disease, often within hours, tissue becomes swollen. Diarrhea and vomiting are also common symptoms, followed by necrosis of skin.

• Treatment: v

ery sensitive to penicillin

Good prognosis.

Streptococcus pneumoniae penicillin-resistant strains remain susceptible to vancomycin

Question 36

Infectious Disease:

Streptococcal Pyogenes:

Pharyngitis (Strep throat)

Answer 36

• Description: highly contagious infection in the throat and tonsils, common cause of sore throat in children and teens, if left untreated may lead to other more severe pathologies like kidney inflammation, heart damage or arthritis. Symptoms include scratchy throat that is very painful and swollen lymph nodes. Spreads through droplets, shared drinks or direct contact.
• Etiology: Group A streptococcus pyogenes
• Pathogenesis: invasion of bacteria causing exotoxins, adhesion, colonization and replication activating an innate immune response in the bloodstream

Clinical Features: fever, sore throat, painful swallowing, white (or red) patches on throat and tonsils, enlarged lymph nodes, headache, rash, nausea and vomiting.

• Treatment: rapid strep test in Dr.’s office (5 min) antibiotics, if left untreated may lead to autoimmune diseases like scarlet fever (rash), poststreptococcal glomerulonephritis (kidney), rheumatic fever (heart) or arthritis.

Question 37

Infectious Disease:

Streptococcal Pyogenes:

Rheumatic fever

Answer 37

Definition or description: untreated infection of Group A streptococcal pyogenes bacteria that may stimulate an immune response and affects multiple organ systems like the heart, joints and central nervous system. Rheumatic fever affects the heart and it’s valves. Most often affects children between 5-15 years. Rare in North America.
Etiology (cause): group A streptococcus infection causing an autoimmune reaction

Pathogenesis: autoantibodies are produced attacking normal tissues, causing widespread inflammation.

• Clinical Features: fever and may affect multiple organ systems, cardiovascular (carditis, or valve damage), musculoskeletal (polyarthritis), skin (nodules & erythema-rash), central nervous system (chorea)

Treatment: anti inflammatories, antibiotics

Question 38

Infectious Disease:

Streptococcal Pyogenes:

Necrotizing Fasciitis

Answer 38

• Description: bacterial infection that attacks and destroys skin, fat, connective tissues (superficial fascia) over muscles, also called flesh eating disease, may be very serious and is potentially fatal. May be spread with direct contact. It spreads quickly along fascial planes, more commonly in the extremities.
• Etiology (cause): Group A streptococcus
• Pathogenesis: bacteria enters a wound or crosses the skin barrier causing an immune response
• Clinical Features: red, swollen and hot skin, fever and chills, nausea and vomiting and diarrhea, if serious may spread quickly and lead to organ failure and shock. The damaged tissue may develop gangrene. More common in the immunocompromised, diabetics, smokers, alcoholics and those with cancer.
• Treatment: surgery to remove infected tissues, antibiotics, hyperbaric oxygen therapy

Question 39

Infectious Disease:

Pneumococcal Infections:

Streptococcus Pneumoniae

Answer 39

Description: this bacteria occurs normally in the upper respiratory tract flora but in susceptible people may cause pneumonia, sepsis, sinusitis, otitis media or meningitis. It is the most common cause of community acquired pneumonia and meningitis. It spreads by direct person to person contact with respiratory droplets. The very young and very old are most susceptible and most seriously affected. Often follows influenza or a viral respiratory infection.

Etiology: streptococcus pneumoniae (or pneumococcus), becoming pathogenic under the right circumstances.

Pathogenesis: this bacteria attaches to nasopharyngeal cells, sticks to them and colonizes uncontrollably. From there they may migrate to eustachian tubes, sinuses, bloodstream or be inhaled into the lungs which stimulates an inflammatory response causing plasma, blood and white blood cells to fill the alveoli.

Clinical Features:
pneumonia: cough with sputum production, fever and sharp chest pain on inspiration.
otitis media: middle ear infection, fever, ear pain, inflammation and a feeling of fullness.
sinusitis: inflammation of sinuses, not contagious, sinus headache, facial tenderness, pressure or pain in the sinuses, fever, cloudy discolored drainage, nasal stuffiness, sore throat and cough.
meningitis: inflammation of the meninges, high fever, headache and stiff neck

Treatment: vaccine, antibiotics

Question 40

Pathology - Infectious Disease

Pyogenic Bacterial Infection

Gonococcus (Gonorrhea)

Answer 40

Description: a sexually transmitted infection of the urogenital tract, but may also infect the pharynx, eyes and rectum. Infection occurs most often through sexual activity (genital, oral, anal) or from an infected pregnant woman to her baby during vaginal delivery. Untreated gonorrhea may lead to: pelvic inflammatory disease (PID), gonococcal arthritis, endocarditis and septicemia.

Etiology: gonococci, species of neisseria gonorrhoeae

Pathogenesis: transmission, adherence, colonization, invasion and immune system evasion instigating an inflammatory response causing epithelial damage.

Clinical Features: systemic common symptoms: fever, chills, joint pain and swelling, skin rash or may be asymptomatic.
Men: more frequent symptoms, penile discharge, swollen testicles, frequent and painful urination (polyuria and dysuria) and sore throat.
Women: thick vaginal discharge, localized burning and itching, abdominopelvic pain, frequent and painful urination (polyuria and dysuria) and painful intercourse (dyspareunia).

Treatment: antibiotics for affected person and all sexual partners. Abstinence or use of condoms is recommended.

Question 41

Pathology - Infectious Disease

Bacterial

Meningococcal Infections

Answer 41

Description: inflammation of the fluid and the membranes of the meninges causing meningitis and septicemia. Affects the pia and arachnoid layers that swell due to the inflammation, pus forms around the brain. 25% of the time persons with meningitis either have permanent brain damage or die. Very serious in newborns. Early flu like symptoms.

Etiology: most often viruses and the meningococcus bacteria

Pathogenesis: bacteria enter bloodstream and travel to brain and spinal cord, viral (enterovirus) are less severe

Clinical Features: often severe, severe headache, hyperextended stiff neck, nausea, vomiting, photophobia, lethargy, rash, multiple organ failure, shock, chills and fever. Skin may become hypersensitive with a red spotty rash. As the condition worsens: dizziness or vertigo, nausea and projectile vomiting, mental disorientation and seizures.

Treatment: antibiotics and anticonvulsive medication (if present). Corticosteroids to reduce inflammation and swelling.

Question 42

Anaerobic Bacterial Infections

Answer 42

Anaerobic Bacterial Infections: Q

Require no oxygen, or oxygen is toxic to them, often found in necrotic or devascularized tissues. It is suppurative (pus forming), causes abscess formation and tissue necrosis

Obligate: live and grow in the absence of oxygen 

Facultative: can survive without oxygen

Examples: diptheria, plague, botulism, cholera

Question 43

Pathology - Infectious Disease

Anaerobic Toxic Infection

Corynebacterium Diphtheria

Answer 43

Description: diphtheria is an acute bacterial infection that affects mucous membranes, the respiratory tract, tissues lining the ears, eyes and genital areas and the skin. If untreated may damage heart, kidneys or nervous system. Spreads by contact and secretions or airborne droplets of the nose, mouth and skin. Very rare in North America due to widespread vaccination.

Etiology: corynebacterium diphtheriae

Pathogenesis: this bacteria produces toxins that cause localized inflammation and destruction of local cells.
Clinical Features: skin infections with inflammation and necrosis of local tissues, fever, malaise, sore throat, hoarseness, lymphedema, difficulty breathing and difficulty swallowing. A grey, thick pseudomembrane forms over the throat and tonsils and in severe cases can extend down the tracheobronchial tree.

Treatment: antibiotics, diphtheria antitoxin (neutralizing the circulating diphtheria toxin and reducing the progression of the disease) and vaccinations.

Question 44

Pathology - Infectious Disease

Anaerobic Toxic Infection

Yersinia Pestis

Answer 44

Description: has many names “The Plague”, “Bubonic Plague”, “Black Death”Q, it is a bacterial infection of the lungs. Transmitted by fleas on rats, those fleas bite humans and other mammals and transmit the bacteria. Causes fever, headache, chills and weakness.

Etiology: yersinia pestis bacteria carried by fleas on rodents who then bite humans, transmission also via human to human inhaling droplets, highly contagious with a 50% mortality rate.

Pathogenesis: while in bloodstream, avoidance of phagocytes and other immune cells allow it to replicate uncontrollably and cause inflammation and cell destruction.

Clinical Features: severe pneumonia, massive lymphadenopathy (enlarged lymph nodes called buboes), high fever, progresses to septicemia (may be life threatening), fever, headache, weakness, cough productive of bloody or watery sputum.

Treatment: antibiotics, no vaccine

Question 45

Pathology - Infectious Disease

Anaerobic Toxic Infection

Clostridium Botulinum

Answer 45

Description: commonly known as botulism, a bacteria found to cause severe food poisoning with paralyzing effects. Home canned foods low in acid cause most cases of this food borne pathology. When in the bloodstream the bacteria produces dangerous toxins that block nerve functions and lead to respiratory or muscular paralysis. Symptoms appear 12-36 hours after ingestion.

Etiology: clostridium botulinum with three significant types: C. difficile, C. tetani and c. botulinum. C. botulinum: produces botulinum toxin in food causes botulism. Honey sometimes contains spores which may cause infant botulism. The toxin eventually paralyzes the infant’s breathing muscles.
(KNOW 3 TYPE)

Pathogenesis: food borne bacteria often found in home canned foods, vegetables, fish, fruits, meat and dairy products enters body and produces toxins that bind to nerve endings at the neuromuscular junction. This prevents the nerves from signalling the muscles to contract causing paralysis.

Clinical Features: nausea, vomiting, abdominal cramps, diarrhea, weakness and paralysis
muscle weakness characteristically starts in the muscles supplied by cranial nerves (eye movements, facial muscles and muscles of mastication). Double vision, drooping of both eyelids, loss of facial expression, swallowing problems, difficulty talking, weakness then spreads to the arms and legs followed by respiratory muscles.

Treatment: antitoxin that blocks the action of the neurotoxin circulating in the blood. Breathing tube may be necessary.

Question 46

How does Botox work?

Answer 46

Attacks proteins at the neuromuscular junction, prevent vesicles from releasing the neurotransmitter acetylcholine. This interferes or stops nerve impulses and causes flaccid paralysis of muscles. The muscles right under the skin are flaccid or constantly relaxed, so no wrinkling of the skin.

Question 47

Pathology - Infectious Disease

Anaerobic Toxic Infection

Coliforms

Answer 47

Description: fecal coliforms are bacteria that are normally found in the digestive tract (they ferment lactose) so are also in the feces. Coliforms are found in water, soil, vegetation and feces. The more of them indicates feces contamination but also the presence of other pathogenic bacteria. They are used to measure and determine sanitary quality of foods and water. Escherichia coli is a virulent strain and causes gastroenteritis and urinary tract infections. Fecal–oral transmission is the main source of transmittance.

Etiology: escherichia coli strains are generally harmless, but some strains can cause serious food poisoning.

Pathogenesis: once ingested, the bacteria invades and replicates in epithelial cells causing inflammation, destroying them.

Clinical Features: wide range of symptoms from mild to bloody diarrhea, nausea, fever, vomiting, stomach cramping and dehydration being the main cause of death! Coliforms are an opportunistic bacteria and may cause wound infections in susceptible individuals.

Treatment: hydration both oral and IV (intravenous), do not use antibiotics as they further imbalance the digestive bacteria and make symptoms worse. Q

Question 48

Pathology - Infectious Disease

Anaerobic Toxic Infection

Coliforms - Cholera

Answer 48

Description: an infection causing watery diarrhea leading to severe and rapid dehydration, may be fatal within hours. Rare in North America. Transmitted in contaminated water or raw shellfish.

Etiology: vibrio cholerae

Pathogenesis: infection via water contaminated with excrement of infected hosts, once in the body secretes a toxin in the small intestine and releases a toxin that promotes the excretion of fluids and electrolytes which induces watery diarrhea.

Clinical Features: severe watery diarrhea, leads to dehydration, oliguria, and shock, rapid onset of smelly diarrhea called “rice water stool”, vomiting, wrinkled skin, low blood pressure, dry mouth and rapid heart rate are also common symptoms.

Treatment: rehydration, electrolytes, antibiotics

Question 49

Pathology - Infectious Disease

Mycobacterial Infection

Tuberculosis

Answer 49

Definition or description: an infectious inflammatory systemic disease that affects mostly lungs but also may affect lymph nodes and other organs. It is spread by airborne droplets and is the leading cause of infection in the world. There is latent TB (bacteria remain inactive in body, not contagious, no symptoms) and active TB (contagious and symptomatic). TB on the rise due to HIV on the rise and drug resistant strains for treating TB.

Etiology (cause): mycobacterium tuberculosis

Pathogenesis: caused by inhaled droplets that establish in the lungs causing caseous granulomas

Clinical Features: causes pneumonia, meningitis, pericarditis, urogenital infections, may become widespread throughout the body, fever, night sweats, chest pain, fatigue, weight loss, persistent cough (with blood), tiredness, loss of appetite, diagnosed with culture sputum or skin test.

Treatment: antibiotic cocktail for at least 6-9 months, vaccination

Question 50

Leprosy

Answer 50

Description: infectious bacterial disease causing discoloured skin sores and growths, nerve damage and nasal symptoms. Primarily effects nerves of the extremities, the skin, lining of the nose and upper respiratory tract. Spread with close and repeated contact with nose and mouth droplets of someone who is infected. More common in children. Mostly in Africa and Asia.

Etiology: mycobacterium leprae
General mechanism of action of nerve growth factor (NGF) in the systemic immune response, neuroinflammation, regeneration, and tissue repair. NGF acts on lymphocytes, mast cells, and macrophages to induce inflammation. NGF acts on fibroblasts and keratinocytes to induce tissue repair. NGF acts on oligodendrocytes, Schwann cells, and neurons to induce repair or apoptosis

Pathogenesis: genetic factors and/or activation of the innate immune system targeting schwann cells causing demyelination

Clinical Features: takes 3-5 years for symptoms to show, affects mostly skin and peripheral nerves causing disfiguring skin sores and growths, thick, stiff dry skin, painless ulcers on soles of feet, loss of eyebrows or eyelashes, numbness and tingling of arms and legs, muscle weakness or paralysis especially in hands and feet and also may affect eyes and nasal passages.

Treatment: antibiotics for at 1-2 years, does not reverse already present nerve damage

Question 51

Pathology - Sexually Transmitted Diseases or Infections

Chlamydia

Answer 51

Description: The most common sexuallly transmitted bacterial infection, last decade increased by 143% in Canada. The infection is in the urogenital tract (urinary and genital). It is called the “silent STD” because symptoms are minor or absent so transmission occurs unknowingly. It is the most common cause of pelvic inflammatory disease (PID) and ectopic pregnancy. Often accompanied by a gonorrhea or syphilis infection (20-30%). Transmitted via genital, anal or oral contact with an infected person or may be transmitted from mother to baby during vaginal delivery. Infection rates are 55% between partners with a 10% chance of a single act transmission with an infected person.

Etiology (cause): the bacterium chlamydia trachomatis

Pathogenesis: whole process is not fully understood, epithelial cells in mucosal sites around the body are the primary target of this bacteria. The bacteria lives and reproduces inside these cells eventually killing them, but first causing inflammation and damage.

Clinical Features: May be asymptomatic, enlarged lymph nodes (lymphadenopathy), oropharyngeal infection. Untreated 80% of infections disappear within one year and 90% within two years. Rarely, may cause infertility.

Women: burning and itching with thick vaginal discharge, urethritis, cervicitis, conjunctivitis, pelvic inflammatory disease, abdominal pain, painful urination (dysuria) and painful intercourse (dyspareunia)
Men: burning and itching with penile discharge, painful urination (dysuria), urethritis, epididymitis, conjunctivitis Q
Infants: conjunctivitis, neonatal pneumonia

Treatment: antibiotics for both partners, abstinence & condom use until treatment is complete

Question 52

Pathology - Sexually Transmitted Diseases or Infections

Gonorrhea

Answer 52

Description: A bacterial infection of the urogenital tract, but may also infect the pharynx, eyes and rectum. Cases have increased by 124% in the last decade. Transmitted usually by genital, oral or anal contact or by mother to infant during vaginal delivery. If untreated may lead to pelvic inflammatory disease, gonococcal arthritis, endocarditis or septicemia. Often occurs with chlamydia. Known as “the clap”.

Description: “the clap”

The name the clap has three different origin stories.
Early 1900’s GI’s infected during wartime had symptoms of gonorrhea they colloquially called “the collapse” shortened to “the clap”.
One major symptom of gonorrhea is a pus like penile discharge, people believed by clapping their hands on either side of the penis could forcefully expel the pus and cure the infection (they also used boat paddles, or books like the bible).
The french word for brothel is “clapier” and we know that most gonorrhea was transmitted in these establishments.

Etiology: Neisseria gonorrhoeae

Pathogenesis: transmission, adherence, colonization and invasion, and immune evasion, the bacterium expresses many virulence factors to promote survival and replication while remaining minimally invasive and minimally discoverable by immune cells. It attacks mucosal surfaces like reproductive tract, pharynx, rectum, conjunctiva causing an inflammatory response and damage. Most often begins at the cervix for women

Clinical Features: May be asymptomatic, enlarged lymph nodes (lymphadenopathy), oropharyngeal infection. Untreated 80% of infections disappear within one year and 90% within two years. Rarely, may cause infertility.

Women: burning and itching with thick vaginal discharge, urethritis, cervicitis, conjunctivitis, pelvic inflammatory disease, abdominal pain, painful urination (dysuria) and painful intercourse (dyspareunia)
Men: burning and itching with penile discharge, painful urination (dysuria), urethritis, epididymitis, conjunctivitis

Question 53

Trichomoniasis

Answer 53

Description: a sexually transmitted protozoal (parasite) infection that affects the lower urogenital tract. Often co infected with gonorrhea also. The parasite can be transmitted from an infected mother to her newborn during birth

Etiology: trichomonas vaginalis

Pathogenesis: once in the bloodstream adheres to epithelial cells and destroys them while causing inflammation and replicating.

Clinical Features: frothy, pale yellow to green, odorous vaginal discharge, with local itching and redness, also painful urination (dysuria). Infected men are usually asymptomatic, but they may have a scant penile discharge, with slight itching and painful urination.

Treatment: single dose of metronidazole (Flagyl) an antibiotic and antiprotozoal medication. All sexual partners are treated simultaneously to prevent re-infection.

Question 54

Vaccinations

Answer 54

Contains antigenic material derived from the microorganism (or membrane proteins). This small amount of antigenic material contained in a vaccine stimulates the adaptive immune system to respond by forming antibodies and produces cytotoxic T cells. Administered intramuscularly, subcutaneously, intradermally, orally or intranasally. Smallpox (1796), polio, measles and tetanus have been irradicated from many parts of the world because of vaccination. One of the most noteworthy allegations of vaccine-induced injury is the MMR vaccine controversy. A fraudulent 1998 paper by Andrew Wakefield, originally published in The Lancet, presented supposed evidence that the MMR Vaccine (an immunization against measles, mumps and rubella that is typically first administered to children before their first birthday) was linked to the onset of autism spectrum disorders. The article was partially retracted in 2004 by Wakefield’s co-authors, and was fully retracted by The Lancet in 2010.