Respiratory Tract Infections Flashcards
(58 cards)
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
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
3
Q
What are upper RT infections?
A
- pharyngitis
- otitis media
- rhinosinusitis
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%)
5
Q
What type of infection is the common cold?
A
- viral infection
- many different strains
6
Q
What type of URTI is more common?
A
Viral
7
Q
When is a throat swab completed?
A
- when group A strep is suspected
- otherwise, a nasopharyngeal swab is done
8
Q
What type of bacteria are streptococci and staphylococci?
A
- gram positive
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
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
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
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
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
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
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
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
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)
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)
19
Q
What pathogen is the most common cause of community acquired infections?
A
Streptococcus pneumoniae
20
Q
What pathogen is the most common cause of hospital acquired infections?
A
Gram negatives (H. influenzae)
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
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
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
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
What are the causes of viral pneumonia?
- influenza virus; seasonal (spring and fall) & pandemic (H1N1)
- parainfluenza virus
- respiratory syncytial virus (RSV)
26
What are the symptoms of influenza?
- sudden and high fever, pharyngitis, congestion, dry cough, malaise, myalgias, headache
- no SOB
27
What is viral pneumonia?
- 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
Does normal lung auscultation rule out pneumonia?
No; the only way to rule out or to diagnose pneumonia is with a chest x-ray
29
What will an x-ray show if pneumonia is present?
- 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
What is required to diagnose pneumonia?
- a chest x-ray along with a constellation of symptoms and signs are required to establish a diagnosis of pneumonia
31
What other diagnostic tests can be done to identify pneumonia and its severity?
- 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
What determines whether a client with pneumonia should be hospitalized?
1) severity of illness
2) possible complications
3) status of underlying conditions
33
The first organ to be affected by pneumonia-related complications, such as sepsis, is...
- the kidneys
34
The 5-year mortality rate for pneumonia is...
50%
35
What tools are available to determine if a client requires hospitalization?
- CURB-65
- Pneumonia Severity Index (PSI)
- SMART-COP
- A-DROP
36
What is CURB-65?
- 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
What other factors should be considered for hospitalization?
- 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
What should be considered for antibiotic therapy?
- antibiotic susceptibility profile
- penetration of bronchial tree
- consider antibiotic exposure within past three months; the infectious pathogen may be resistant
39
Systemic corticosteroid therapy in clients with severe CAP reduces the rate of...
- 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
How can pneumonia be prevented?
- hand-washing
- annual influenza vaccine; patients with chronic medical conditions, all HCPs, and household contacts of high-risk patients
- pneumococcal vaccine
41
What are pneumococcal vaccines?
- 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
What is the efficacy of pneumococcal polysaccharide vaccine in high risk groups?
- 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
What is tuberculosis?
- most common infectious cause of death worldwide
- estimated 30% of world is infected
- caused by mycobacterium tuberculosis
44
What are some characteristics of mycobacterium tuberculosis?
- 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
How is TB transmitted?
- 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
What is primary TB?
- 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
What is latent TB?
- 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
What antibiotics are used to treat latent TB?
- Isoniazid: 6-9 months; pregnant women and children <11 years, HIV
- Rifampin: 4 months
49
TB Skin Test
- 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
What is secondary TB?
- 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
What diagnostic measures are taken for active pulmonary TB?
- 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
What are drawbacks for bronchoscopy?
- invasive, infectious risks
| - less sensitive than sputum samples
53
What is the risk for reactivation of TB?
- 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
What is disseminated (extrapulmonary) tuberculosis?
Will affect:
- brain
- kidneys
- spine
- ex. tuberculosis lymphadenitis
55
TB should be considered in those with these symptoms...
- 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
How is TB treated?
- 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
Who is considered an immunocompromised host?
- underlying disease (HIV)
- therapy (ex. post transplant medications)
- susceptible to bacteria, virus, fungi, and parasites
58
What are possible opportunistic pathogens?
- 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
