Session 9: Respiratory tract infections

Question 0

Acute pharyngitis

Answer 0

greater than 90% is viral

• Rhinovirus: common cold
• Coronavirus: common cold
• EBV: mono
• Coxsackle: herpangia

Question 1

Pharyngitis

Answer 1

40% are virus origin: includes common cold, mono, inflammation of pharynx to infectious agent, often co-exists with tonsillitis

Question 2

common cold

Answer 2

more than 100-200 different virus causes, so immunity is not a protective factor, no vaccines available.

• 30 to 50% are rhinoviruses (113 serotypes)
• direct contact transmission
• 15 to 20% are coronaviruses
• easily spread to sinuses, lower res. tract, middle ear
• triggers asthma

Question 3

infectious mono: “Kissing Disease”

Answer 3

cause- EBV: HHV 4, enveloped

IM: infectious mononucleosis

• have it very young and mild infection
• gets severe when you get older
• systemic effect on cardiovascular and lymphatic system
• virus shed intermittently from saliva through life

Symptoms: fever, sore throat, swollen lymph glands in neck, weakness, fatigue, enlarged spleen

• production of heterophile antibodies, used in lab tests
• ampicillin rash: systemic syndrome

Question 4

pharyngitis details

Answer 4

• streptococcus pyogenes (group A), GAS- beta hemolytic streptocci
• GAS pharyngitis: most common GAS infection, often in school aged children, in 15 to 30% of cases
• direct contact
• incubation is 2-4 days

Question 5

Acute rheumatic fever

Answer 5

• caused by previous GAS pharyngeal infection with latent period of 2-4 weeks
• disorder most common among children 5-15 years
• occur in developing countries

Question 6

Rheumatic fever

Answer 6

• non infectious complication of strep A (s. pyogenes) infection
• after one month, untreated strep throat infection
• prevent is to TREAT all throat infections!

Question 7

scarlet fever

Answer 7

symptoms: rash on neck and face around mouth, then spreads to chest and body.

6 days: rash will go away, fever is 101 F and over, sore throat- very red, pass soon after fever

Question 8

Scarlet fever is caused by….

Answer 8

a bacteriophage! (viruses of bacteria that carry DNA that goes into the bacteria) that has a toxin that kills epithelial cells

• Tonsils: swollen, coated in white substances with yellow dots
• Strawberry tongue: very red, has white and pink dots
• other: chills, body aches, throwing up with nausea, decreased appetite.

Question 9

Whooping cough

Answer 9

aka 100 days cough

• bordetella pertussis: small gram negative, aerobic, coccobacillus
• important exotoxins: tracheal cytotoxin: damages ciliated cells, pertussis toxin: enters blood stream and cause systemic effects
• vomiting, droplet and mucous transmission

Question 10

Diphtheria

Answer 10

caused by corynebacterium diphtheriae, gram positive bacillus, non spore forming

• doesn’t invade tissues: produce exotoxin ( inhibit protein synthesis in host cells)
• toxin diffuses out into tissues ( tropism) for nerves
• once leading cause of mortality in children
• vaccination helped

Symptoms:
-sore throat, fever, malaise, neck swelling, nerve paralysis, white gray membrane across back of throat ( fibrin, dead tissue, bacterial cells, WBC)

Question 11

Diphtheria pathogenesis

Answer 11

pathogenesis: produces toxins that cause death in epithelia cells of the throat
- result is inflammation, accumulation of phagocytes
- thick gray membrane grows at the back of the throat and bleeds if you try to dislodge it
- membrane has dead epithelia cells, fibrin, toxin that can prevent breathing

Question 12

C. diptheridae bacteria

Answer 12

apathogenic unless lysogenized or transduced by a bacteriaphage which transfers a gene that encodes for a toxin

• all isolates must be tested for toxin production
• effects are myocarditis, cardiac failure, polyneritis

treatment: antibiotics and antitoxin, vaccine is effective by older people only have 20% protection due to lack of boosters.

COTANEOUS DIPHTHERIA is common in tropics

Question 13

mycobacterium

Answer 13

characteristics: gram positive, non-motile rod, lipid rich cell wall containing myolic acid. 3-8 weeks to grow into colony

morbidity/incidence: active TB: cough, weakness, fever, weight loss, high sweats, cough up blood, chest pain

latent TB: body’s immune system has contained the infection ( 1 in 3 person)

Infectious cycle: TB and AIDS go hand in hand

• airborne
• GRANUOLOMA formation is crucial to maintain a control

Question 14

3 things that happen after M. Tuberculosis exposure

Answer 14

1. Latent infection: no activation of macrophages
2. Primary tubercle forms, but immune system stops replication
3. military infection: spread of active infection ( immunocompromised people)

Active infection: aka military infection, can be from primary or reactivation of a latent infection. Symptoms include weight loss, fever, nightsweats, chronic cough , blood, lethargia

Question 15

TB continued

Answer 15

Lab diagnosis: finding of acid fast rods in sputum, culture ( up to 6 weeks for negative result), quantiferon gold test for activated T-lymphocytes

Skin tests: test for cell-mediated acquired immunity, PPD ( purified protein derivative) injected subcutaneously and measured in diameter, Mantoux test

Vaccine: BCG: bacillus calmette-guerin, live culture of M. bovis, only given to children at high risk in North America, effectivity 0% in adults

Treatment: multiple drug regimens to prevent development of drug resistance. takes 6 months to a year. Patient is not infectious after 2-3 weeks on drugs

Question 16

Pneumonia ( old man’s friend)

Answer 16

Cause: typical- S. pneumoniae, responds to penicillin treatment
atypical- caused by other organisms, penicillin resistant, includes virus, bacteira, fungi
- most common cause of infection deaths
- cause in children is viral, cause in adult is bacterial

Question 17

Pneumococcal pneumonia

Answer 17

• encapsulated gram positive diplococcus (S. pneumoniae- alpha hemolytic)
• involves alveoli and bronchi

symptoms:
- fever, rust colored blood, breathing problmes, chest pain
- spreads to blood
- vaccines exist ( polysaccharide/conjugate)

Question 18

RSV

Answer 18

Characteristics: RNA, enveloped
cause: tissue damage by synctia formation
spread: direct contact
risks are premature infants, children less than 5 years
- epidemic: late winter and early spring
-causes bronchiolitis and pneumonia in infants, coughing and wheezing

Question 19

influenza A

Answer 19

characteristics: enveloped, orthomyxoviridae. Segmented: negative sense genome, A and B = 8 RNA segments, C=7 segments, only A has subtypes
symptoms: malaise, fever, headache, myalgia, cough, sore throat, severe in smokers

incubation period: small infectious dose, incubation 1-5 days, virus viable on hard surface 24-48 hours, droplet transmission

Question 20

pandemic vs epidemic influenza

Answer 20

pandemic: caused by antigenic SHIFT: preformed antibodies against virus A and have some effect on virus B
3 to 4 in every 100 years, significant mortality rates, global disease spread in 6 to 9 months, usually start in china

epidemic: caused by antigenic DRIFT: reassortment of RNA segment
annual occurrence in late winter, early spring: temperate conditions
-30,000 deaths per year in the US with every epidemic
-nosocimal infections common in nursing homes

Question 21

Infections of the oral cavity

Answer 21

• bacteria needs iron to grow
• about 1 to 1.5 L of saliva secreted a day from salivary glands: flush mouth, lysozome, lactofemin, contain secretory IgA, lactoperoxidase, WBC
• dehydrated patients: mouth overgrown with organisms, bad breath

Question 22

bad breath

Answer 22

• caused by the waste products of anaerobic oral bacteria
• most of the compounds cause bad breath (hydrogen sulfide, cadaverine, etc) are waste products of bacterial metabolism.
• anterior ( front) of tongue often gets flora rubbed off

Question 23

Candida albicans

Answer 23

• opportunistic fungus, yeast like in culture outside of body, pseudohyphae in tissues ( tongue)
• common cause of mouth and throat infection: inhalation steroids, chemotherapy, broad spectrum antibiotic, immune defects and cancer ( young and old)

Question 24

oral candidasis

Answer 24

- upset in balance of flora - thrush: growth of mycelium of pseudohyphae in tongue - spread to esophagus

Question 25

Actinomycosis: Lumpy jaw

Answer 25

- painful abscesses caused by an anaerobic bacterium, "Actinomyces israeli" ( normal flora in oral cavity) - cause abscesses in pelvis and lung - abscess formation, healing and scarring leads to deformation of tissue: lumpy jaw - tendency to chronic infection - dental procedures ( wounds) trigger infection

Question 26

Vincent's disease ( trench mouth)

Answer 26

also called acute necrotizing ulcerative gingivitis (ANUG) or Vincent's angina - anaerobic gram negative bacilli - anaerobic gram negative spirochaetes - severe ulcerative disease, pain, breath is foul smelling treatment is antibiotics and surgery

Question 27

Infection of the parotid gland: Mumps

Answer 27

characteristics: RNA, paraymyxovirus, droplet transmission, salivary gland, most infectious 48 hours before symptoms begin - virus multiple in lymph gland in throat, then penetrate the parotid gland via blood. symptoms: inflammation and swelling of parotid glands, fever, pain on swallowing complications: encephalitis, orchitis ( testis), oophoritis, sterility

Question 28

infection of stomach: Helicobacter pylori

Answer 28

- cause of peptic ulcer disease ( gastric and duodenal) - spiral shaped gram negative microaerophilic bacterium - associated with contaminated water and wells - has flagella that allows movement in thick mucus. - produces large amounts of urease, urea is broken down to ammonia and pH locally diagnosis: urea breath test (C14 labelled urea) - drink solution and breath out, if urease present, then carbon dioxide exhaled will be marked. - serology, culture of biopsy specimens

Question 29

predominant flora of intestine

Answer 29

bactericides ( dominate) disease of Gi tract are 2 types: 1. infections: pathogens multiples in mucosa ( poisons) or passes to other systemic organs ( fever- vomiting, release of endotoxin-LPS) 2. intoxications: ingestion of a preformed toxin from usually sudden onset and no fever Result: diarrhea ( MAJOR CAUSE OF INFANT MORTALITY- DEHYDRATION)

Question 30

main pathogenic mechanisms of lower alimentary tract pathogens

Answer 30

- attachment - cell invasion - loss of microvilli ( function for reabsorption) - toxic production ( increase secretion of waste and electrolytes) ( decrease protein synthesis and cause cell death)

Question 31

dysentery vs. gastroenteritis

Answer 31

dysentery: - severe diarrhea with blood, often pus and or mucous - includes E. histolytica, shigella dysenteriae Gastroenteritis: - inflammation of the stomach and intestine mucosa, no pus - include vibrio cholerae, crytosporidium common symptom of both: nausea, vomitting, abdominal cramps, diarrhea

Question 32

causes of intoxications

Answer 32

staphylococcus aureus (Vomiting) : meats, custards, salads bacillus cereus ( Vomitting, diarrhea): rice, meat, veggies clostridium botulinum ( neuromuscular paralysis): improper preserved veggies, fish, meat

Question 33

S. aureus

Answer 33

- produce exotoxins called enterotoxins - heat stable, resistant to enzymatic - destruction in GI tract - grows quickly and easily in food - salt tolerant, osmotically stable - 30 minutes to heat - temperature in food is warm - custard, gravy, cream pie, ham - adequate refrigeration prevention

Question 34

S. Enterotoxin

Answer 34

- triggers Vomiting reflex - causes abdominal cramps - usually occurs in 2 to 4 hours after ingestion - complete recovery within 24 hours - no lasting side effects - GRAVY!

Question 35

Bacillus cereus

Answer 35

food associated disease with 2 forms: 1. diarrhea: production of enterotoxin in gut ( 8 to 16 hour) infection 2. Vomitting: ingestion of enterotoxin in food (1-6 hour) gram positive bacilli, aerobic, spore forming usually harmless otherwise heating food may not kill spores, common in rice dishes self-limiting disease

Question 36

salmonellosis ( salmonella enterica ssp enterica gastroenteritis)

Answer 36

- gram negative, non spore forming bacilli, motile - sensitive to acid, need large numbers to cause an infection - common commensals in GI tracts of animals on reptile skin, turtles and snakes

Question 37

salmonella gastroenteritis

Answer 37

- over 2000 serotypes - enteritis and typhimurium most common in developing countries - incubation 12-36 hours - susceptible to gastric acid, needs lots of bacteria - meat products, eggs,poultry - s. enteritis infect chicken, but EGGS infected ONLY - usually not treated with antibiotics

Question 38

Typhoid Fever (S. enterica typhi)

Answer 38

spread only from human to human - high fever 40 degrees, headache - diarrhea starts in 2 to 3 weeks - causes sepsis ( enteric fever) - bacteria multiply in phagocytic cells, disseminate quickly to blood - carrier state after recovery - antibiotics is the treatment

Question 39

Shigellosis

Answer 39

- it is an infection, not intoxication, gram negative bacilli, non-motile - 4 species total: S. dysenteriae (A) is most severe! - virulent strains has plasma essential for attachment and entry of bacteria into cells - transmission is from person to person, no animal reservoir ( fecal oral) - produces shigatoxin (cytotoxin)

Question 40

campylobacter gastroenteritis

Answer 40

- gram negative, spiral formed bacilli ( gull wings) - leading cause of food-borne illness in Canada and US - commensals of poultry and cattle, can be in water - 80 to 90% of poultry have campylobacter - C. jejuni is the most common cause ( infective dose 500 stomach acid tolerance) - self-limiting disease - prevention is hygienic measures associated with handling of poultry etc. and monitoring of water - can get complications of IBD and Guillan Barre Syndrome

Question 41

E. Coli gastroenteritis

Answer 41

- most strains are apathogenic and normal residents of GI tract - pathogenic strains have special fimbriae for attachment (ETEC, EIEC, EPEC, EHEC)

Question 42

Enterohemorrhagic E. Coli (EHEC)- 1982

Answer 42

- Hamburger disease - best known serotype is 0157:H7 (O is cell wall, H is flagella) - it is in animal intestine, cows - produces shiga-like toxins: hemorrhagic colitis (HUS)

Question 43

HUS complication: Hemolytic uremic syndrome

Answer 43

- blood in urine due to kidney failure - 5 to 10% of small children get HUS - present in poorly handled meat, poultry, raw alfalfa sprouts - transmitted by contaminated water - usually on adults, but children and elderly can get it as well - treatment: rehydration and antimicrobials

Question 44

Clostridium perfringens Gastroenteritis

Answer 44

- gram positive bacilli, spore forming, anaerobic - grows in intestinal tract and produce an exotoxin that cause abdominal pain and diarrhea - most causes mild pain, 8-12 hours after ingestion - spores can withstand heating - found in meat dishes - bacterium needs amino acid for growth and when meat is cooked, O2 levels go down

Question 45

Vibrio Cholerae

Answer 45

- gram negative "vibrio" comma shaped bacterium - can have more than 20 fluid loss a day ( RICE WATER STOOL) - survives high pH and high salt - killed by acid, need large numbers to cause an infection - produce exotoxin (cholera enterotoxin), heat labile - fecally contaminated water a major source of infection - treatment is rehydration glucose and electrolytes (antibiotics decrease number of bacteria after rehydration) - global pandemic

Question 46

Viral gastroenteritis

Answer 46

- seen in all parts of the world - in developing countries, it's a major cause of death especially in children - non-distinguishable clinically from other gastroenteritis - viruses are specific to humans - fecal oral transmission - 90% of cases caused by rotaviruses or norwalk viruses

Question 47

rotavirus gastroenteritis

Answer 47

RNA, reoviridae, non-enveloped - most common cause of viral gastroenteritis in children - same incidence in developed and underdeveloped nations - disease of children, most happen less than 2 years - incubation is 2-3 days - often nosocomial - symptom is low grade fever, diarrhea, vomiting - VAcciNE: Rotorix, Rotatea

Question 48

Norovirus (Norwalk virus)

Answer 48

- RNA, non-enveloped - cause major epidemics of viral gastroenteritis (2/3 of cases in food poisioning) - 2 day incubation period, similar to Rotavirus - symptom is nausea, abdominal cramps, diarrhea, Vomitting for 1-3 days, sudden onset, no prodrome

Question 49

protozoan diseases cause diarrhea include....

Answer 49

Giardia lamblia crytosporidiosis Entamoeba histolytica

Question 50

helminthic disease ( no diarrhea) includes...

Answer 50

tapeworm (cestode) | roundworm (nematode)

Question 51

Hepatitis A (HAV)

Answer 51

RNA, non enveloped (picornaviridae) - oral fecal route, water, mollusks - resistant to chlorine - incubation 2-4 weeks - patho:virus multiply in intestinal epithelia cells, enter blood stream and infect livers, kidney, spleen cells, cause damage. Virus exits by biliary tract to feces for excretion Symptoms: nausea, Vomitting, fever, anorexia, jaundice, sudden onset Clinical: 50% of infections are subclinical, no chronic disease Diagnosis: HAV IgM antibodies in serum Immunity: lifelong vaccines exist

Question 52

Hep B

Answer 52

- bloodborne, STI - enveloped DNA virus - Acute infection: liver inflammation, Vomitting, jaundice - Chronic infection: cirrhosis, carcinoma - vaccine available

Question 53

Hep. C

Answer 53

bloodborne - enveloped RNA virus - Acute: mild and vague symptoms - 80% get affected - Chronic: cirrhosis, liver cancer - NO VACCINE

Question 54

Hep. D

Answer 54

- coexist with Hep. B to cause disease! - bloodborne - enveloped RNA virus - only happens if Hep B exist!

Question 55

Hep. E

Answer 55

- RNA, calicivirus - fecal oral transmission - increasing in countries with poor sanitation - no chronic disease - risk for pregnant women, 20% mortality