Ch. 10 - Upper Respiratory Diseases

Question 1

Group A Streptococci - S. pyrogenes

Answer 1

gram positive

streptococcal pharyngitis = strep throat

transmissible through respiratory droplet

virulence factors: M protein (resist phagocytosis); streptokinase (remove fibrin clots)

treatment: ampicillin, amoxicillin; hand hygiene best prevention

Question 2

scarlett fever

Answer 2

strain of s. pyrogenes has genes coding erythrogenic exotoxins

cause pink-red rash on skin – from blood leaking through walls of damaged capillaries

treatment: penicillin

Question 3

rheumatic fever

Answer 3

develop from lack of treatment of strep throat

affects joints and heart

scarring and distortion of heart valves – antibodies confuse heart muscle for M protein

Question 4

Diptheria - corynebacterium diptheriae

Answer 4

gram positive bacteria

transmission from respiratory droplets

bacterial cells secrete exotoxin that inhibits translation – cell death

accumulation of pseudomembrane on tonsils and pharynx

treatment: penicillin

TDaP

Question 5

epiglottitis

Answer 5

epiglottis infected with bacterial pathogen (eg Haemophilus influenzae) - infected in surrounding tissue

inflammation of epiglottis

difficulty breathing - stridor (wheezing sound breathing in/out)

prevention: immunization with Hib vaccine

Question 6

sinusitis

Answer 6

inflammation of the sinuses

begins with viral infection of nasal cavity (rhinitis)

acute sinusitis - blockage at the opening of the sinuses

Question 7

acute otitis externa

Answer 7

outer ear infection

swimmer’s ear - streptococcus, staphylococcus, pseudomonas

Question 8

acute otitis media

Answer 8

middle ear infection

most common

causative agents: streptococcus pneumonia, haemophilus influenza

start with common cold in URT – travel to ear

Question 9

bacterial meningitis

acute bacterial meningitis (ABM)

Answer 9

inflammation of the meninges ( membranes that envelope brain and spinal chord)

attaches to nasopharyngeal mucosa by pili
local URT infection
invasion of epithelium
spread to blood
cross blood-brain barrier
meninges inflamed – pressure on spinal chord and brain

Diagnosis: spinal tap, Gram stain

Symptoms: fever and stiff neck, headache, nausea, vomiting, sensitivity to light

Treatment: penicillin, cephalosporins, vancomycin (may be beta lactamase resistant

Vaccine: conjugate vaccines

Question 10

meningococcal meningitis - neisseria meningitis

Answer 10

encapsulated

gram negative diplococcus - endotoxin + capsule

found in 10% latent worldwide

most common form - accounts for 90% of ABM cases

transmitted via respiratory droplets

High risk: 6mo - 2yrs; young adults – overcrowded places

Question 11

Pneumococcal meningitis - streptococcus pneumoniae

Answer 11

encapsulated

gram positive diplococcus

community acquired meningitis - affecting infants and elderly

treatment: penicillin

Question 12

Haemophilus meningitis - Haemophilus influenzae

Answer 12

encapsulated

gram negative coccobacillus

High risk: 6mo - 4yrs

vaccine: Hib vaccine – combined with TDaP = Tetramune
DTP-HbOC = conjugate vaccine

capsule not as good at stimulating immune response; conjugate to protein, more immunogenic

Question 13

Pertussis – bordatella pertussis

Answer 13

transmitted via respiratory droplets

pili adhere to epithelial cells in mouth/throat

exotoxin - paralyze ciliated epithelial cells – impair mucus movement

stage 1 (catarrhal) - cough, low fever, high bacterial load

stage 2 (paroxysmal) - disintegrating cells and mucus accumulate in airways – labored breathing; paroxysms = rapid coughing in one exhalation

stage 3 (convalescence) - sporadic coughing

“100 day cough”

Treatment: erythromycin during catarrhal stage

Vaccine: DTaP

Question 14

Tuberculosis - mycobacterium tuberculosis

Answer 14

waxy cell wall – more resistant to antibiotics

90% latent infection

transmitted via small aerosol droplets – from person with active pulmonary disease (active TB)

primary infection = pulmonary infection with bacterial cells entering alveoli

infection arrested in tubercle = latent infection

infection spread throughout = active infection (pulmonary TB, Extrapulmonary TB)

miliary TB: tubercles throughout the body (from spread of infection)
Treatment: isoniazid, rifampin, ethambutol

acid fast - resistance to decolorization during staining procedures

Question 15

healthcare-acquired pneumonia

Answer 15

causative agent: staphylococcus aureus, klebsiella pneumonia

inflammation of one or both lungs

s. aureas (gram positive):
- spread through hand contamination

klebsiella (gram negative rod):

• acquired by respiratory droplets
• bloody sputum
• those with impaired lung function

Question 16

community-acquired pneumonia

Answer 16

causative agent: streptococcus pneumonia

Gram positive, encapsulated diplococci

transmitted via aerosol droplets

treatment: penicillin

Question 17

primary atypical pneumonia

Answer 17

causative agent: mycoplasma pneumonia

transmitted via breath droplets

diagnosis: fried egg colony on blood agar plate
treatment: tetracyclines (penicillin will not work!)

Question 18

Legionnaires’ Disease

Answer 18

causative agent: legionella pneumophila

Gram negative rods

live where water collects

airborne transmission

treatment: erythromycin