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Introductory Microbiology > Respiratory Tract Infections > Flashcards

Respiratory Tract Infections Flashcards

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1
Q

What are some characteristics of the upper respiratory tract?

A
  • collects and filters air
  • non-sterile; colonized w/ diphtheroids, S. pneumoniae, and S. aureus
  • tonsils and mucous defend against pathogens
  • mucous contains defensins, lactoferrin, and lysozyme
  • includes the nasal cavity, auditory tube opening, pharynx, and uvula
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2
Q

What are some characteristics of the lower respiratory tract?

A
  • exchange of gas; CO2 and O2
  • typically sterile
  • ciliary escalator, secretory antibodies and phagocytes defend against pathogens
  • no microbial antagonism as with upper RT to outcompete foreign microbes
  • includes epiglottis, larynx, trachea, and respiratory tree
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3
Q

What are upper RT infections?

A
  • pharyngitis
  • otitis media
  • rhinosinusitis
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4
Q

What bacteria cause URTIs?

A
  • PHARYNGITIS: streptococcal pharyngitis/ group A streptococcus (streptococcus pyogenes)
  • OTITIS MEDIA & RHINOSINUSITIS: streptococcus pneumoniae (35%) and haemophilus influenzae (20-30%)
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5
Q

What type of infection is the common cold?

A
  • viral infection

- many different strains

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6
Q

What type of URTI is more common?

A

Viral

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7
Q

When is a throat swab completed?

A
  • when group A strep is suspected

- otherwise, a nasopharyngeal swab is done

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8
Q

What type of bacteria are streptococci and staphylococci?

A
  • gram positive
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9
Q

What is streptococcal pharyngitis?

A
  • caused by group A streptococci (S. pyogenes)
  • pharynx appears red, presence of purulent abscesses and swollen lymph nodes
  • pain during swallowing, bad breath, fever, headache, malaise
  • laryngitis, bronchitis
  • scarlet fever d/t erythrogenic exotoxins
  • glomerulonephritis
  • rheumatic fever (can affect heart)
  • can move into lower RT
  • presence of pustules differentiates bacterial from viral
  • must be treated with penicillin
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10
Q

What is otitis media?

A
  • middle ear infection
  • severe ear pain d/t inflammation and pressure on ear drum
  • can rupture, causing hearing impairment
  • paediatric cases most common (85%) due to anatomy and lower immunity
  • usually caused by a virus
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11
Q

What is rhinosinusitis?

A
  • sinus infection
  • sinus pain and pressure, headache, general feeling of malaise
  • adult cases most common
  • usually caused by a virus
  • more likely to be bacterial if acute and lasting >10 days, accompanied by high fever and pus filled nasal discharge
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12
Q

What is streptococcus pneumoniae?

A
  • gram positive
  • coccoid shaped, grows in pairs and chains
  • primary bacterial pathogen
  • infections commonly move from pharynx to sinuses (via throat), or to middle ear (via auditory tubes)
  • risk of invasive disease: pneumonia, pneumococcal meningitis, bacteremia
  • most of us already colonized with this pathogen
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13
Q

What is the common cold?

A
  • one of the most common human infections
  • numerous viruses responsible (rhinovirus, coronavirus, adenovirus)
  • virus remain infective for hours outside body and are highly contagious
  • exits host cell through lysis
  • transmission via respiratory droplets, fomites, and direct contact; a single virus can cause infection
  • prevention involves hand-washing and routine practices
  • no treatment
  • chills, rigors, sneezing, rhinorrhea, nasal congestion, dry, scratchy sore throat, malaise, and cough lasting about a week
  • no fever unless accompanied by bacterial infection
  • only exist in URT because cannot tolerate higher temp. of LRT
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14
Q

What is pneumonia?

A
  • lower RT infection
  • inflamed, fluid-filled alveoli and bronchioles
  • empyema: presence of pus within the pleural space
  • 6th leading cause of death in Canada and the most common cause of death due to infection
  • generally affects the extremes of age and is more common in the fall and winter
  • length of stay increases significantly in clients >70 years of age
  • 85% of community acquired cases are caused by pneumococcal pneumoniae
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15
Q

How does pneumonia develop?

A
  • pathogens in pharynx are micro-aspirated into lower lobes of the lungs
  • most humans colonized with S. pneumoniae
  • pneumonia develops if not effectively cleared by the immune system
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16
Q

What are risk factors for pneumonia?

A
  • previous viral respiratory disease
  • drug abuse
  • alcoholism (inhibits immune cells and cough reflex)
  • HF, DM, AIDS and other immune conditions
  • extremes of age
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17
Q

What are three important variables that influence pneumonia infection?

A

1) pathogenicity of the organism
2) degree of aspiration
3) health of the host (immune and respiratory systems)

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18
Q

What types of pneumonia exist?

A

1) Community acquired pneumonia (CAP)
- primary atypical pneumonia
2) Nursing home acquired pneumonia (NHAP)
3) Hospital acquired pneumonia (HAP)
- VAP (ventilator associated pneumonia)
- HCAP (health care associated pneumonia)

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19
Q

What pathogen is the most common cause of community acquired infections?

A

Streptococcus pneumoniae

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20
Q

What pathogen is the most common cause of hospital acquired infections?

A

Gram negatives (H. influenzae)

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21
Q

What are pathogenic factors of streptococcus pneumoniae?

A
  • produce adherence factors that facilitate binding to pharyngeal epithelial cells
  • has capsule
  • capable of inducing endocytosis into epithelial cells of the lung
  • produce a cytotoxin (pneumolysin) that induces cell lysis
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22
Q

What are the manifestations of pneumococcal pneumonia?

A
  • transmission via respiratory droplets
  • S. pneumoniae damages alveolar lining
  • RBCs, WBCs, and plasma enter lungs
  • fluid filled alveoli and inflammation impairs gas exchanges, causing pneumonia
  • sudden onset
  • fever, chills, congestion, productive cough, chest pain, SOB
  • rust coloured sputum (blood) with increased neutrophil content
  • can cause invasive diseases such as bacteremia and meningitis if not controlled
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23
Q

What is mycoplasma pneumoniae?

A
  • primary atypical pneumonia
  • high rates of transmission via respiratory droplets, fomites, and direct contact, no seasonality
  • most frequently reported in young adults
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24
Q

What are the manifestations of mycoplasma pneumoniae?

A
  • damage ciliary escalator, inhibiting the removal of mucus from the RT
  • possess adhesins specific to the cilia of respiratory epithelial cells and a capsule; slow growing
  • fever (lower than CAP), malaise, headache, sore throat, excessive sweating, non-productive cough
  • symptoms not typical of other types of pneumonia
  • mucoid (thick, sticky) sputum
  • sometimes referred to as “walking pneumonia”
25
Q

What are the causes of viral pneumonia?

A
  • influenza virus; seasonal (spring and fall) & pandemic (H1N1)
  • parainfluenza virus
  • respiratory syncytial virus (RSV)
26
Q

What are the symptoms of influenza?

A
  • sudden and high fever, pharyngitis, congestion, dry cough, malaise, myalgias, headache
  • no SOB
27
Q

What is viral pneumonia?

A
  • transmission via respiratory droplets
  • can occur in two ways:
    1) primary viral pneumonia
    2) respiratory viral infection followed by bacterial superinfection
  • non-productive cough, low grade fever, myalgias, fatigue, sore throat, headache
  • not as severe as bacterial
28
Q

Does normal lung auscultation rule out pneumonia?

A

No; the only way to rule out or to diagnose pneumonia is with a chest x-ray

29
Q

What will an x-ray show if pneumonia is present?

A
  • the presence of infiltrates (fluid and pus) in one or both lobes
  • no infiltrate means no pneumonia EXCEPT in cases where the client is very dehydrated or immunocompromised, impairing fluid and pus accumulation
30
Q

What is required to diagnose pneumonia?

A
  • a chest x-ray along with a constellation of symptoms and signs are required to establish a diagnosis of pneumonia
31
Q

What other diagnostic tests can be done to identify pneumonia and its severity?

A
  • ABGs
  • CBC
  • electrolytes, renal and liver function tests
  • blood cultures; 2 sets of 2
  • sputum Gram stain and culture
  • NP swab if vital etiology suspected
  • sputum for acid fast bacilli (AFB) and MTb culture to tule out TB
32
Q

What determines whether a client with pneumonia should be hospitalized?

A

1) severity of illness
2) possible complications
3) status of underlying conditions

33
Q

The first organ to be affected by pneumonia-related complications, such as sepsis, is…

A
  • the kidneys
34
Q

The 5-year mortality rate for pneumonia is…

A

50%

35
Q

What tools are available to determine if a client requires hospitalization?

A
  • CURB-65
  • Pneumonia Severity Index (PSI)
  • SMART-COP
  • A-DROP
36
Q

What is CURB-65?

A
  • each letter in “CURB” stands for a clinical factor
  • Confusion
  • Urea (BUN)
  • Respiratory rate
  • Blood pressure
  • 65+
  • a point for each criteria
  • the more points, the more severe the pneumonia and thus the more likely the client should be hospitalized
37
Q

What other factors should be considered for hospitalization?

A
  • hemodynamic stability
  • hypoxemia (PO2 < 60 mmHg & SpO2 < 90%)
  • presence of empyema
  • active co-existing condition requiring hospitalization
  • lack of home support
  • unable to tolerate PO antibiotics (needs IV)
38
Q

What should be considered for antibiotic therapy?

A
  • antibiotic susceptibility profile
  • penetration of bronchial tree
  • consider antibiotic exposure within past three months; the infectious pathogen may be resistant
39
Q

Systemic corticosteroid therapy in clients with severe CAP reduces the rate of…

A
  • mechanical ventilation
  • acute respiratory distress syndrome
  • time to clinical stability
  • duration of hospitalization
  • gains in reducing inflammation through steroids far outweighs the small reduction in immunity
40
Q

How can pneumonia be prevented?

A
  • hand-washing
  • annual influenza vaccine; patients with chronic medical conditions, all HCPs, and household contacts of high-risk patients
  • pneumococcal vaccine
41
Q

What are pneumococcal vaccines?

A
  • routine infant immunization: Pneu-C-13; Prevnar13
  • pneumococcal polysaccharide vaccine; Pneu-P-23; Pneumovax 23)
  • all individuals >65
    and individuals at increased risk for invasive pneumococcal disease > 2 years should receive this vaccine
42
Q

What is the efficacy of pneumococcal polysaccharide vaccine in high risk groups?

A
  • controversial
  • does not prevent pneumonia
  • most think it prevents invasive pneumococcal disease
  • cheap and safe however
  • data suggests reduction in hospitalization rates
  • still recommended for all >65 years
43
Q

What is tuberculosis?

A
  • most common infectious cause of death worldwide
  • estimated 30% of world is infected
  • caused by mycobacterium tuberculosis
44
Q

What are some characteristics of mycobacterium tuberculosis?

A
  • rod-shaped, aerobic bacteria, non-spore forming
  • resists de-colorization by alcohol “acid fast bacilli” and required an acid fast stain for identification
  • surrounded by mycolic acid
  • resistant to chemical agents
  • some bacilli can survive acidic/alkaline environments
  • resistant to drying and can survive in dried sputum
  • additional airborne precautions required
45
Q

How is TB transmitted?

A
  • inhalation of organism-laden droplet nuclei is the most common form of transmission
  • infective in dried aerosol droplets for up to 8 months
  • infection risk depends on organism load of the droplet, frequency and efficiency of cough, closeness of contact and adequacy of ventilation, and host factors
  • host factors include DM, poor nutrition, stress, alcohol and drug use, and smoking
  • primary, secondary and disseminated (extrapulmonary) TB
46
Q

What is primary TB?

A
  • caused by inhalation and deposition of bacilli in lungs
  • 5% of individuals develop primary “active” TB
  • mostly children
  • clients actively sick and infectious
  • serious, productive cough (blood/sputum), lasting 3 weeks or longer
  • chest pain
  • generalized symptoms of weakness and fatigue, weight loss, lack of appetite, chills, fever and night sweats
  • positive x-ray and sputum
47
Q

What is latent TB?

A
  • 95% of individuals will develop latent TB
  • immune system prevents spread and progression of the disease
  • clients are asymptomatic and not infectious
  • negative x-ray and sputum
  • usually present with a positive TB skin test or blood test
  • at risk for development of TB disease if not treated, must assess risk factors
48
Q

What antibiotics are used to treat latent TB?

A
  • Isoniazid: 6-9 months; pregnant women and children <11 years, HIV
  • Rifampin: 4 months
49
Q

TB Skin Test

A
  • tuberculin (antigen) is injected into the skin of the lower arm
  • 48-72 hours post-test client is assessed for a reaction
  • positive skin test: hard, red swelling at test site means client is infected with TB
  • negative skin test: no reaction, latent TB is unlikely, but does not exclude active TB
  • 20-25% of those with active TB have a negative result
50
Q

What is secondary TB?

A
  • latent infection reactivates, and client exhibits symptoms of post-primary “active” TB
  • serious, productive cough (blood/sputum) lasting 3 weeks or longer, chest pain
  • same symptoms as primary TB
  • positive x-ray and sputum
  • medical history, physical exam, x-ray and microbiology all required for diagnosis
  • 55% mortality if untreated, 15% with treatment
51
Q

What diagnostic measures are taken for active pulmonary TB?

A
  • early AM sputum; 3 daily collections yield positive results in most cases
  • induced sputum hypertonic heated saline aerosol
  • if unable to produce sputum: early AM gastric aspirates w/ children, bronchoscopy (BAL)
52
Q

What are drawbacks for bronchoscopy?

A
  • invasive, infectious risks

- less sensitive than sputum samples

53
Q

What is the risk for reactivation of TB?

A
  • 5-10% will reactivate during lifetime
  • those at high risk include:
  • those with HIV
  • people infected with TB in last two years
  • babies and young children
  • elderly people
  • those who inject illegal drugs
  • immunocompromised
  • those not treated correctly for TB in the past
54
Q

What is disseminated (extrapulmonary) tuberculosis?

A

Will affect:

  • brain
  • kidneys
  • spine
  • ex. tuberculosis lymphadenitis
55
Q

TB should be considered in those with these symptoms…

A
  • unexplained weight loss
  • loss of appetite
  • night sweats
  • fever
  • fatigue
  • non-resolving “pneumonia”
  • should be referred for a complete medical evaluation & history, physical exam, chest x-ray, and diagnostic microbiology
56
Q

How is TB treated?

A
  • select treatment regimen of 6-9 months
  • iIsoniazid, rifampin, ethambutol, pyrazinamide
  • modify when susceptibility test available (weeks for growth & additional time for testing)
  • address Public Health issues
  • monitor for drug toxicity e.g. liver, kidney, eye damage
  • monitor for adherence
  • evaluate response to therapy
  • watch for multi-drug resistant (MDR) and extensively MDR strains (XDR)
57
Q

Who is considered an immunocompromised host?

A
  • underlying disease (HIV)
  • therapy (ex. post transplant medications)
  • susceptible to bacteria, virus, fungi, and parasites
58
Q

What are possible opportunistic pathogens?

A
  • pneumocystis pneumonia (PCP)
  • typically associated with AIDS
  • may also be seen in other types of immunocompromised settings (malnourished infants, frail elderly)
  • always should be diagnosed with an x-ray and sputum

Introductory Microbiology (11 decks)

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