Respiratory Tract Infections Flashcards
1
Q
Otitis Externa Etiologies
A
Psuedomonas aeruginosa and Staphylococcus aureus
2
Q
Pseudomonas aeruginosa description
A
Gram-negative encapsulated bacilli. Produces fluorescent blue/green pigments pyocyanin (virulence factor, produces ROS) and pyoverdin. Infectious isolates have pili.
3
Q
Staphylococcus aureus description
A
Gram-positive encapsulated cocci in clusters.
4
Q
Staphylococcus aureus Culture
A
Coagulase positive (gold standard) and Beta-hemolytic
5
Q
AOM and Sinusitis Etiologies
A
Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis.
6
Q
Streptococcus pneumoniae Description
A
Gram-positive, lancet-shaped, encapsulated diplococci.
7
Q
Streptococcus pneumoniae Culture
A
Alpha hemolysis with optochin sensitivity.
8
Q
Moraxella catarhalis Description
A
Gram-negative diplococci
9
Q
Moraxella catarhalis Culture
A
Oxidase positive. Beta-lactamase producer.
10
Q
Diphtheria Etiology
A
Corynebacterium
11
Q
Corynebacterium Description
A
Gram-positive pleomorphic bacilli. Palisades (V or chinese letters appearance). Metachromatic volutin granules. Green organism with dark stained granules.
12
Q
Diptheria toxin
A
A-B exotoxin. Stimulated by low iron concentrations. Binds the heparin-binding EGF and is endocytosed. The vesicle becomes acidified and releases the A subunit. The A subunit inactivates EF-2 via ADP- ribosylation and halts protein synthesis.
13
Q
Cutaneous Diphtheria Presentation
A
Chronic ulcers usually due to non-toxigenic strains.
14
Q
Respiratory Diphtheria presentation
A
Sudden onset of malaise, exudative pharyngitis, low-grade fever and LAD (“bull neck”). Forms a pseudomembrane in the pharynx made of fibrin, bacteria, WBC and necrotic epithelial cells. Systemic toxicity can lead to myocarditis and demyelination.
15
Q
Corynebacterium culture
A
Loeffler’s medium (enhances formation of the volutin granules) and cysteine-tellurite agar (definitive test).
16
Q
Diphtheria Diagnosis
A
Gram stain (positive with volutin granules), culture, Elek test (immunodiffusion assay of the toxin), PCR, ELISA, immunochromatographic strip assay.
17
Q
Pertussis Etiology
A
Bordetella pertussis
18
Q
Bordetella pertussis Description
A
Small, gram-negative coccobacilli
19
Q
Bordetella pertussis virulence factors
A
endotoxin, adhesins, exotoxins
20
Q
Bordetella pertussis adhesins
A
Mediate the attachment to integrins to colonize the ciliated respiratory epithelium. Filamentous hemagglutinin, pertactin and agglutinogens.
21
Q
Bordetella pertussis A-B exotoxin
A
Dysregulates cAMP and inhibits phagocytes. Causes lymphocytosis.
22
Q
Bordetella pertussis adenylate cyclase toxin
A
Decreases chemotaxis
23
Q
Bordetella pertussis Dermonecrotic toxin
A
Causes vasoconstriction that can lead to necrosis
24
Q
Bordetella pertussis tracheal cytotoxin
A
Kills ciliated respiratory cells. Allows infection of the lower respiratory tract.
25
Pertussis disease stages
Catarrhal: inflammaiton of the mucous membranes with nonspecific URI symptoms but is highly contagious. Paroxysmal: attacks/spasms, paroxysmal coughing often followed by vomiting, characteristic "whoop" can last for weeks.
Convalescent: Gradual recovery
26
Pertussis Complications
pneumonia, encephalopathy, seizures and death
27
Pertussis epidemiology
Usually occurs in children less than 1 yo.
28
Bordetella pertussis Culture
Grows on enriched selective medias. Bordet-Gengou agar (definitive) and Regan-Lowe (Gray/silver colonies).
29
Pertussis Diagnosis
Serology for the toxin or adhesins, culture, PCR for the toxin gene.
30
Acute Respiratory Disease Etiologies
Rhinovirus, coronaviruses, Adenoviruses
31
Rhinovirus Epidemiology
Hyperendemic during the winter. Usually occurs in children and you adults. Transmission occurs with direct contact and through aerosols. Immunity is transient.
32
Rhinovirus Treatment
Zinc gluconate (cold eeze) and picovir (inhibits viral binding).
33
Influenza Serotypes
Type A > Type B > Type C. Subtypes are based on envelope proteins, H=hemagglutinin (attachment) and N=neuraminidase (penetration and release).
34
Influenza Presentation
Abrupt onset of fever, aches, chills and cough, that usually lasts a week.
35
Influenza complications
Primary influenza pneumonia, Secondary/bacterial pneumonia (S. pneumoniae, S. aureus, Hib), Reyes syndrome and Guillain-Barre syndrome.
36
Reyes syndrome
Acute, catastrophic systemic disorder. Edematous encephalitis and fatty alteration of liver tissue. Usually seen in kids 6 mo-15 yo. Associated with influenza and the chicken pox that is treated with aspirin.
37
Guillain-Barre Syndrome
Demyelination that can be induced by the vaccination but there is a ten fold higher risk from the natural infection.
38
Influenza Diagnosis
Direct isolation from throat/nasopharyngeal swabs or rapid antigen detecting kits (can give false negatives).
39
Amantadine/rimantadine
Treats influenza type A. Stops uncoating and penetration. Some resistance has emerged.
40
Ostemivir (tamiflu)/ zanamivir (relenza)
Treats influenza type A and type B. Neuraminidase inhibitors that stop the release and spreading. Resistance has emerged.
41
Influenza vaccine
Trivalent contains two type A and one type B virus that is predicted to be most likely. Children less than 9 yo require two administrations for their first time. Can result in mild flu-like symptoms.
42
Influenza vaccine target groups
Adults over 65, long term care facilities, pulmonary/cardiac chronic conditions, asthma, immunosuppressed, DM, renal dysfunction, hemoglobinemias, pediatric patients on aspirin therapy, healthcare workers.
43
Antigenic Drift
Point mutation in the H or N genes that causes minor genetic variation.
44
Antigenic Shift
Exchange of genomic segments. Causes major genetic variation. Occurs more in type A due to it's segmented genome and wide range of hosts.
45
Influenza Nomenclature
type/location of discovery/year of isolation/isolation number/antigenic type
46
Chlamydiae
Obligate intracellular parasite. Biochemically restricted so has to use host ATP.
47
Chlamydia trachomatis presentation
Infant pneumonia (onset at 3 weeks). Rhitis follow by a cough. Transmitted to the neonate by the mother through vaginal delivery. At risk for reiter's syndrome
48
Chlamydophila pneumonia presentation
Can cause bronchitis, pneumonia, sinusitis and is associated with atherosclerosis.
49
Croup presentation
Syndrome of fever, hoarseness and a barking cough. Most common in children 6-18 mo. Results from varying degrees of laryngeal obstruction.
50
Croup etiology
PIV type 1 > PIV type 2 >>> RSV
51
Parainfluenza Virus (PIV) Description
Nonsegmented, negative sense, ssRNA genome. Virion is enveloped with protein spikes.
52
PIV presentation
Harsh cough, rhinitis, sore throat, SOB. 2-3% leads to croup. In adults PIV presents as a nonspecific URI.
53
PIV Complications
Otitis media, parotitis.
54
PIV Epidemiology
Most common in the fall/winter. Type 1 and type 2 are alternating epidemics in the fall. Type 3 is sporadic in later winter/ early spring. Life long immunity is not observed.
55
PIV Diagnosis
Direct fluorescent antibody test or RT-PCR.
56
Respiratory Syncytial Virus (RSV) Presentation
Cough, dyspnea, cyanosis and sometimes croup. IgE mediated.
57
RSV Diagnosis
Rapid antigen tests or nucleic acid tests
58
RSV Treatment
Immune globulin (Palivizumab) also used as prophylaxis. Ribavirin is used only if supportive treatment fails.
59
RSV Epidemiology
Annual winter outbreaks. Most common lower respiratory infection in children younger than 4 yo (peak incidence in less that 1 yo).
60
RSV risk factors
Prematurity, cardiac/respiratory abnormalities, birth a few months before RSV season.
61
SARS description
Severe Acute Respiratory Syndrome. Coronavirus. Emerging new infection that is now considered extinct. Zoonotic.
62
Bacterial Pneumonia Definition
Inflammation of the lung parenchyma with the build up of fluid, inflammatory mediators, debri and necrotic tissue that restricts airflow
63
Nosocomial definition
Develops 72 hours or more following hospital admission
64
Typical pneumonia etiologies
S. pneumoniae, H. influenzae, K. pneumonia, S. aureus.
65
Atypical pneumonia symptoms
Gradual fever that is less than 103 degrees, non-productive cough, patchy infiltrates, well appearing, body aches, diarrhea, abdominal pain.
66
Atypical pneumonia etiologies
Chlamydiphla pneumoniae, mycoplasm pneumoniae, legionella pneumoniae.
67
Typical pneumonia symptoms
Sudden fever that is greater than 103, ill appearing, productive cough, chills, pleurisy, consolidation, chest pain, SOB.
68
Streptococcus pneumoniae epidemiology
Cold/wet months. Children and those over 65 yo. Asymptomatic carriers are the main reservoir. There are 25 infectious serotypes.
69
Streptococcus pneumoniae virulence factors
Capsule, IgA protease, hydrogen peroxide, pili, adhesins, choline binding protein, peptidoglycan-teichoic acid, pneumolysin (specific to S. pneumoniae), neuraminidase/hyaluronidase, autolysin (specific to S. pnemoniae).
70
Pneumolysin
S. pneumoniae virulence factor. Interacts with host cells to form transmembrane pores leading to lysis. Activates complement to increase inflammation. Produced during stress.
71
Autolysin
S. pneumoniae virulence factor. Causes the lysis of pneumococcus. Attempt by the organism to dampen the host immune response. Destroys one layer of the biofilm to overwhelm the immune system. Released in response to antibiotic therapy and stationary phase.
72
Clinical presentation of Streptococcus pneumoniae
Typical Pneumoia: rust colored sputum. Otitis media, sinusitis, bacteremia, meningitis, arthritis, peritonitis.
73
23-valent pneumococcal vaccine
Covers 90% of the serotypes. Recommended in adults older than 65 yo and those with high risk.
74
13-valent pneumococcal vaccine
Covers 80% of the serotypes in children younger than 6 yo. Conjugated to a carrier protein. Covers most of the penicillin resistant strains.
75
Streptococcus pneumoniae Diagnosis
Gram-positive diplococci. Alpha-hemolytic (green colonies on RBC agar), optochin sensitivity, Bile solubility (only alpha hemolytic that is lysed by bile), agglutination tests for the capsule, genetic probe test.
76
Streptococcus pneumoniae DOC
Penicillin G
77
Chlamydophila pneumoniae Description
Atypcial pneumonia. Gram negative obligate intracellular parasite. Life cycle exists of elementary bodies (spores/infectious) and reticulate bodies (intracellular).
78
Chlamydophila pneumoniae Pathogenesis
Direct tissue destruction and inflammatory response. Posesses 2 exotoxins. Primary response is from PMNs so no long lasting immunity.
79
Chlamydophila pneumoniae Presentation
Atypical pneumonia. Can be asymptomatic. Persistent non-productive cough with malaise. Unilateral lower lobe involvement.
80
Chlamydophila pneumoniae epidemiology
Humans are the only reservoir. Most common in adults older than 60 yo.
81
Chlamydophila pneumoniae Diagnosis
cell culture and microscopy for serology and PCR.
82
Chlamydophila pneumoniae Treatment
Tetracycline/erythromycin
83
Haemophilus Influenzae Description
Non-motile, gram-negative, coccobacillus. Has lipooligosaccharide (LOS) instead of LPS. Requires RBCs but isn't capable of lysis. Can be encapsulated or not. Non-typeable H. influenzae is able to lose it's capsule and is part of normal flora. Type B (Hib) can cause pneumonia in children.
84
Haemophilus Influenzae Virulence factors
Polyribosylribitol phosphate (PRP) capsule, neuraminidase, IgA protease, Fimbriae, LOS.
85
Haemophilus Influenzae Pathogenesis
Non-typeable causes infection due to imbalance of colonization. Non-encapsulated strains have adhesisns with bind to the epithelium resulting in loss of the cilia and sloughing off of cells (LOS).
86
Haemophilus Influenzae Diagnosis
Gram staining (negative), serological testing (capsule), Culture, Latex agglutination test (tests for antigens not viable bacteria).
87
Haemophilus Influenzae Culture
Must be cultured on chocolate agar (lysed RBC) with hemin and NAD at 37 degrees celcius with CO2. Or can be grown as a satellite around S. aureus (not diagnostic).
88
Haemophilus Influenzae Treatment
Augmentin
89
Klebsiella pneumoniae description
non-motile, gram-negative bacillus with a thick/slimy capsule.
90
Klebsiella pneumoniae Epidemiology
Found in the normal flora. Causes typical CAP and nosocomial pneumonia. Mainly seen in the immunocomrpomised (alcoholics, DM, homeless).
91
Klebsiella pneumoniae Virulence factors
polysaccharide capsule, Adhesins (fimbriae).
92
Klebsiella pneumoniae Presentation
Caused by aspiration of normal oropharyngeal microbes. Aggressive necrotizing CAP usually in the upper lobes. Causes the destruction of alveoli. Rapid onset of fever and often fatal. Currant jelly sputum.
93
Klebsiella pneumoniae Diagnosis
Gram stain (negative), culture (mucoid capsule), CXR (cavitation).
94
Klebsiella pneumoniae Treatment
Empiric therapy with aminoglycoside, third generation cephalsporin and/or a flouroquinolone
95
Mycoplama pneumoniae Description
Very small bacteria that lacks a cell wall (doesn't gram stain). Plasma membrane contains sterols.
96
Mycoplama pneumoniae Culture
"fried egg" appearance on many different media.
97
Mycoplama pneumoniae Presentation
Atypical CAP. Non-productive cough that lasts 1-2 months, fever, crackles, HA, CP. Can cause otitis, rhinitis, pharyngitis and tracheobronchitis.
98
Mycoplama pneumoniae epidemiology
Most common in people 5-20 yo. Relapses are common because it fuses to the hosts cell membrane so there is no long term immunity.
99
Mycoplama pneumoniae Diagnosis
CXR (patchy infiltrates), sold aggluntinin assay (detects IgM that binds the I antigen on RBC)
100
Mycoplama pneumoniae treatment
azithromycin/tetracycline
101
Legionella pneumoniae description
thin, pleomorphic, gram-negative bacillus, fimbriae with a polar flagellum. Produces beta lactamase. Usually caused by serotype 1. Facultative intracellular parasite.
102
Legionella pneumoniae pathogenesis
Bacterial cells are inhaled and opsonized with C3b then phagocytized. Survive intracellulary by inhibiting the phagolysosome. Replicates inside the cell then kills the host cell and releases toxic enzymes along with the bacteria. Huge inflammatory response can lead to necrosis.
103
Pontiac fever
Legionella pneumoniae. Self-limited illness that lasts 2-5 days and doesn't require treatment. Fever, chills, malaise, HA.
104
Legionnaire's Disease
Legionella pneumoniae. Severe, acute, atypical CAP. High mortality rate. Fever, chills, non-productive cough, HA, GI, neurological symptoms. Acute fibropurulent necrotizing pneumonia.
105
Legionella pneumoniae Epidemiology
Found in nature and moist environments. Inhalation of aerosols from contaminated water (rivers, sewage, showerheads). Capable of replication in protozoans.
106
Legionella pneumoniae Risk factors
Large inoculum and a compromise in pulmonary or immune function. Smoking, COPD, elderly, alcoholics.
107
Legionella pneumoniae Diagnosis
Culture on a buffered charcoal yeast extract medium (BCYE). Rapid antigen test of the urine (ELISA) for serotype 1.
108
Legionella pneumoniae Treatment
Levofloxacin or azithromycin
109
Pseudomonas aeruginosa virulence factors
pyocyanin (ROS production), A-B exotoxin (inhibits protein synthesis), Elastases, Alginate (slime layer), glycocalyx, pili, lipopolysaccharide (endotoxin).
110
Pseudomonas aeruginosa Epidemiology
Widespread in the environment. used extensively in bioremediation. Carried on skin, fomites and in feces. Opportunistic infections.
111
Pseudomonas aeruginosa Presentations
UTI, pneumonia, eyes, ears, skin, burn patient, CF (often the cause of death).
112
Pseudomonas aeruginosa Diagnosis
Culture (BAP and MacConkey) produces water-soluble blue/green pigment with a "fruity" smell.
113
Pseudomonas aeruginosa Treatment
Cefepime and levofloxacin
