Exam 3 Flashcards
(130 cards)
What physiologic mechanisms do the lungs have to normally resist infection and impair host defense mechanisms?
Upper Airways:
- Nasopharynx: nasal hair, turbinates; anatomy of upper airways; mucociliary apparatus; IgA secretion
- Oropharynx: saliva; sloughing of epithelial cells; complement production
Conducting Airways:
- Trachea, bronchi: cough, epiglottic reflexes; sharp, angled, branching airways; mucociliary apparatus; immunoglobulin production (IgG, IgM, IgA)
Lower Respiratory Tract:
- Terminal airways, alveoli: alveolar lining fluid (surfactant, fibronectin, complement, immunoglobulin); cytokines (TNF, IL-1, IL-8); alveolar macrophages (produce cytokines and recruit neutrophils, so the area becomes acidic and hypoxic); PNMs; cell-mediated immunity
What etiologic organisms are commonly encountered in community-acquired pneumonia, hospital-acquired pneumonia, and ventilator-associated pneumonia?
CAP: pneumonia developed outside of the hospital or <48h after hospital admission. Bacterial pneumonia is most commonly caused by aspiration.
- Viral cause most common
1. Streptococcus pneumoniae
- Haemophilus influenzae, Mycoplasma pneumoniae, Legionella pneumophila, Chlamydia pneumoniae
HAP & VAP: pneumonia occurring ≥ 48h after hospital admission; pneumonia occurring > 48-72h after endotracheal intubation
- aerobic gram-neg bacilli: P. aeruginosa, enteric gram-neg bacilli, Acinetobacter baumannii
- S. aureus (MRSA)
What etiologic organisms are commonly encountered in acute bacterial exacerbations of chronic bronchitis?
H. influenzae - 45%
S. pneumoniae - 20%
M. catarrhalis - 30%
- Enterobacterales, P. aeruginosa - seen in end-stage COPD
What is the common microbial etiology of pharyngitis?
Viruses are most common.
Streptococcus pyogenes are the most common bacterial pathogen.
What is the common microbial etiology of acute bacterial rhinosinusitis?
Haemophilus influenzae
Streptococcus pneumoniae
Moraxella catarrhalis
What is the clinical presentation of a pt with CAP, HAP, and VAP?
CAP: Usually a sudden onset of fever, chills, pleuritic chest pain, dyspnea, productive cough (but more gradual and lower severity with Mycoplasma pneumoniae and C. pneumoniae), tachycardia, tachypnea (& cyanosis, nasal flaring), consolidation
- In elderly: classic symptoms may be absent; may be decline in functional status, weakness, mental status, anorexia, abdominal pain
- Radiography: dense lobar consolidation
What is the clinical presentation of a pt with acute bronchitis, acute bacterial exacerbations of chronic bronchitis, pharyngitis, and sinusitis?
Acute bronchitis - cough, coryza, sore throat, malaise, headache, fever, normal chest x-ray
Acute bacterial exacerbations of chronic bronchitis - chronic cough productive of sputum on most days for at least 3 consecutive months each year for two years. 3 cardinal symptoms include increased cough/dyspnea (SOB), increased sputum volume, and increased sputum purulence
Pharyngitis - Sudden onset of sore throat with dysphagia, fever, pharyngeal hyperemia and tonsillar swelling, enlarged, tender lymph nodes, red, swollen uvula.
*cannot differentiate between bacterial and viral etiology, unless overt viral features are present
Sinusitis - Up to 4 weeks of purulent nasal drainage accompanied by nasal obstruction, facial pain-pressure-fullness, or both;
What determines the diagnosis of ABRS (acute bacterial rhinosinusitis)?
- Onset of persistent symptoms or signs compatible with acute rhinosinusitis, lasting for ≥10 days without any evidence of clinical improvement
- Onset with severe symptoms or signs of high fever (≥ 39ºC) and purulent nasal discharge or facial pain lasting for at least 3-4 consecutive days at the beginning of the illness
- Onset with worsening symptoms or signs characterized by the new onset of fever, headache, or increase in nasal discharge following a typical viral URTI that lasted 5-6 days and was initially improving (“double sickening”)
What are appropriate examinations and diagnostic/lab tests to assist in the diagnosis of respiratory tract infections?
- PCR (for respiratory viruses)
- NPV
- chest X-ray
- WBC w/ differential
- serum creatinine
- BUN
- electrolytes
- LFTs (more likely altered in legionella)
- procalcitonin
- O2 sat
- urinary antigen tests (not routinely used)
- sputum exam (in hospital)
- cultures
- blood cultures (if suspected HAP or VAP)
What risk factors are associated with infections caused by multidrug-resistant Streptococcus pneumoniae, methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa in CAP and MDR organisms in HAP/VAP?
MDR Streptococcus pneumoniae - antibiotic use w/in prev. 3 months, over 65 years old, DM, chronic lung disease/asthma, CAD/CHF, dialysis, HIV, alcohol abuse, cirrhosis, malignancy, use of an immunosuppressive medication
MDR MRSA - concurrent/recent influenza infection, hx of skin infection with CA-MRSA, necrotizing pneumonia or cavitary infiltrates, rapid progression of symptoms, respiratory failure, ICU admission, formation of empyema
MDR Pseudomonas aeruginosa - ??
MDR organisms in HAP/VAP - Prior IV antibiotics within 90 days, at least 5 days of hospitalization prior to occurrence of VAP, septic shock at time of VAP, ARDS before VAP, acute renal replacement therapy prior to VAP
What is the appropriate empiric antimicrobial therapy for the treatment of outpatient CAP (in pts w/ or w/o risk factors for resistant bacteria)?
- Hypoxemic -> Humidified oxygen, bronchospasm -> bronchodilators (albuterol), fluids, chest physiotherapy if needed
- Duration of treatment should be 5 days minimum, based on clinical stability
Healthy outpatient adults w/o comorbidities:
- amoxicillin 1g PO q8h (preferred)
- doxycycline 100mg PO q12h
- macrolide (if resistance is <25%, but likely won’t be used as monotherapy): azithromycin 500mg PO day 1, then 250mg for 4 days; clarithromycin 500mg PO q12h or 1000mg ER daily
Outpatients with comorbidities: (ex. chronic heart, lung, or renal disease, diabetes mellitus, alcoholism, malignancy, asplenia or immunosuppressive condition/drugs)
- Respiratory fluoroquinolone: levofloxacin 750mg daily, moxifloxacin 400mg daily
- combo therapy: β-lactam + macrolide OR β-lactam + doxycycline
- β-lactams: amox/clav, cefpodoxime, cefuroxime
- macrolide
- doxycycline
What is the appropriate empiric antimicrobial therapy for the treatment of inpatient CAP (inpatient non-severe, inpatient severe, inpatient + MRSA or P. aeruginosa concern)?
Inpatient non-severe: no risk factors for MRSA or P. aeruginosa
- β-lactam + macrolide OR β-lactam + doxycycline: amp/sul; ceftriaxone 1-2g IV q24h; azithro/clarithromycin
- respiratory fluoroquinolone monotherapy
- If contraindicated to FQs and macrolides: β-lactam + doxycycline 100mg IV/PO q12h
Inpatient severe: no risk factors for MRSA or P. aeruginosa
- β-lactam + macrolide (preferred)
- β-lactam + respiratory fluoroquinolone
Inpatient + concern for MRSA and/or P. aeruginosa
- MRSA: add vanc or linezolid
- P. aeruginosa: add coverage with pip/tazo, cefepime, ceftazidime, aztreonam, meropenem, imipenem (no ertapenem or daptomycin)
What is the appropriate directed antimicrobial therapy for the treatment of CAP (in pts w/ or w/o risk factors for resistant bacteria) when the organism(s) is (are) known? (S. pneumoniae, H. influenzae, mycoplasma pneumoniae/Chlamydia pneumoniae, legionella pneumophila, staphylococcus aureus, anaerobes, and enterobacterales)
Streptococcus pneumoniae:
- pen-susceptible: pen G or amoxicillin
- pen-resistant: respiratory FQ, ceftriaxone, cefotaxime
H. influenzae:
- non β-lactamase producing: ampicillin IV, amoxicillin
- β-lactamase producing: 2nd or 3rd gen cephalosporin, amp/sulbactam, amox/clav
Mycoplasma pneumoniae or Chlamydia pneumoniae:
- macrolide, doxycyline
Legionella pneumophila:
- fluoroquinolone, azithromycin
Staphylococcus aureus:
- methicillin-susceptible: nafcillin, cefazolin
- methicillin-resistant: vancomycin, linezolid
Anaerobes: β-lactam/β-lactamase inhibitor, clindamycin
Enterobacterales: 3rd or 4th gen cephalosporin, carbapenem
What is the appropriate empiric antimicrobial therapy for the treatment of HAP? (low risk, MRSA, high-risk)
Not at high risk of mortality & no increasing likelihood of MRSA -> provide coverage for MSSA
- pip/tazo, cefepime, imipenem OR meropenem
Not at high risk of mortality but factors for MRSA:
- pip/tazo, cefepime, ceftaidime, imipenem, meropenem, levofloxacin, ciprofloxacin, OR aztreonam
- PLUS vanc OR linezolid
High risk of mortality or prior IV antibiotic use during prior 90 days:
- Two of the following: [pip/tazo, cefepime, ceftazidime, imipenem, meropenem], [levofloxacin OR ciprofloxacin], [aminoglycoside, OR aztreonam]
- PLUS vanc OR linezolid
What is the appropriate empiric antimicrobial therapy for the treatment of VAP?
All empiric regimens should cover S. aureus, P. aeruginosa, and other gram-negative bacilli (Enterobacterales)
β-lactams w/ antipseudomonal activity: pip/tazo, cefepime, ceftazidime, imipenem, meropenem, aztreonam
non-β-lactams w/ antipseudomonal activity: ciprofloxacin, levofloxacin, amikacin, gentamicin, tobramycin, colistin, polymyxin B
Include an agent against MRSA (vanc or linezolid) if:
- risk factors for MRSA
- pts treated in ICUs where 10-20% of S. aureus isolates are methicillin-resistant
- pts treated in ICUs where prevalence of MRSA is unknown
If empirically covering MSSA: pip/tazo, cefepime, imipenem, meropenem (cefazolin, nafcillin, or oxacillin if directed therapy for MSSA)
Prescribe 2 antipseudomonal antibiotics from different classes ONLY if:
- risk factors for antimicrobial resistance
- patients in ICU where over 10% of gram-neg isolates are resistant to monotherapy agent
- pts in ICUs where local resistance rates are unknown
What is the appropriate directed antimicrobial therapy for the treatment of HAP and VAP when the organism(s) is (are) known? (MSSA, MRSA, Enterobacterales, ESBL producer, MBL producer, KPC producer, P. aeruginosa monotherapy, Acinetobacter baumannii, MDR to all other options)
MSSA - cefazolin, nafcillin, oxacillin
MRSA - vanc or lineolid
Enterobacterales - lots of options
ESBL producer - carbapenem (DOC), ceftazidime/avibactam
MBL producer - aztreonam + ceftazidime/avibactam empirically; aztreonam monotherapy if susceptible; cefiderocol
KPC producer - ceftazidime/avibactam, meropenem/vaborbactam, imipenem/cilastatin/relebactam, cefiderocol
Pseudomonas aeruginosa - monotherapy; if pt in septic shock for high risk of death -> combo therapy to which isolate is susceptible; if MDR -> ceftolazane/tazo, ceftazidime/avi, imipenem/cilastatin/relebactam, cefiderocol
Acinetobacter baumannii - carbapenem or ampicillin/sulbactam if susceptible; if resistant to carbapenem or sulbactam -> cefiderocol, sulbactam/durlobactam
MDR to all other options -> Polymyxin B
Treatment should be 7 days
What is the appropriate empiric antimicrobial therapy for the treatment of acute bronchitis?
NO ANTIBACTERIAL THERAPY WARRANTED
Treatment should only be symptomatic (ex. antitussives, antipyretics, adequate hydration). Avoid corticosteroids
What are the risk factors we need to assess with acute exacerbations of chronic bronchitis? (7)
Age 65
COPD severity
>4 exacerbations/year
Cardiac disease
Home oxygen use
Antibiotic use in last 3 months
Recent corticosteroid use
What is the appropriate empiric antimicrobial therapy for the treatment of acute exacerbations of chronic bronchitis when the organism(s) is (are) known? (uncomplicated, complicated, complicated w/ pseudomonas risk) + duration
Treatment should be 5-7 days with the goal of prompt resolution of symptoms and positively influence the duration of patient’s symptom free post-treatment period.
Uncomplicated - <65 years old, FEV > 50%, < 4 exacerbations/year, no comorbidities, no risk factors
- azithryomycin, clarithromycin
- 2nd/3rd gen cephalosporin
- doxycycline
- amoxicillin
- TMP/SMX
Complicated - ≥ 2 risk factors
- Respiratory fluoroquinolone
- Amox/clav
Complicated + Pseudomonas - severe symptoms, constant, purulent sputum, FEV <35%
- ciprofloxacin or levofloxacin
- piperacillin/tazobactam
- IV coverage if hospitalized
What is the appropriate empiric antimicrobial therapy for the treatment of pharyngitis or sinusitis?
Pharyngitis - symptomatic care
- Group A strep: penicillin V is the drug of choice!, amoxicillin is #2, can use 2nd gen cephalosporins as an option if penicillin or amoxicillin fails; 10 day course
- Group A strep + pen-allergic: 1st gen cephalosporin if no anaphylaxis; macrolide (azith/clarith), clinda; 5 day course
Sinusitis - symptomatic care
1. Amox/clav
- if β-lactam allergy: doxycyline, levofloxacin, moxifloxacin
- if risk for antibiotic resistance or failed initial therapy: amox/clav higher dose, levofloxacin, moxifloxacin
- if severe infection requiring hospitalization: amp/sulbactam, levofloxacin, moxifloxacin, ceftriaxone
- macrolides only in pen-allergic pts due to high prevalence of resistance in S. pneumoniae
- TMP/SMX has high resistance rates in S. pneumoniae
What is the pathogenesis, risk factors, bacterial etiology, and symptoms of impetigo?
Pathogenesis - (1) organism can directly invade healthy skin, (2) organism introduced into superficial layers of the skin during trauma or abrasions
Risk factors - Children, skin trauma, hot/humid climates, poor hygiene, day care settings, crowding, malnutrition, diabetes
Bacterial etiology - Most cases caused by Staphylococcus aureus and/or Streptococcus pyogenes (Group A strep)
Symptoms - Maculopapular lesions that rupture, leaving superficial erosions that are occasionally pruritic or painful with honey-colored crust. Can be non-bullous or bullous
What is the pathogenesis, risk factors, bacterial etiology, and symptoms of cellulitis?
Pathogenesis - Organism is introduced to the skin during trauma, woulds, Athlete’s feet, dry, crackled skin, injection drug use, ulcers, or surgery
Risk factors - Diabetes, IV drug use, arterial or venous insufficiency, obesity, lymphedema, immunocompromised
Bacteriology - Depends on patient age and/or risk factor. In infants an children -> H. flu, S. pyogenes, S. agalactiae (neonates); Staph is a common one; If the infection has an abscess, it’s due to CA-MRSA
Symptoms - Rapidly spreading area of redness, tenderness, warmth, and swelling in the skin with a POORLY defined border. May also see fever, malaise, regional lymphadenopathy, lymphangitis, leukocytosis, especially with a deeper infection.
What is the pathogenesis, bacterial etiology, and symptoms of necrotizing fasciitis?
Pathogenesis - Same as cellulitis, but it’s caused by a toxin-producing organism that progressively destroys superficial fascia and subcutaneous fat
Bacteriology - If monomicrobial -> group A strep (S. pyogenes), S. aureus (probs CA-MRSA); if polymicrobial -> mix of aerobes and anaerobes from the GI or GU tract
Symptoms - Cellulitis and intense pain, bullae, crepitus, wooden-hard induration, cutaneous gangrene and systemic toxicity (fever, MS changes, hypotension)
What is the pathogenesis, risk factors, bacterial etiology, and symptoms of diabetic foot infection?
Pathogenesis - Caused by the presence of neuropathy, angiopathy with ischemia, dry skin, decreased wound healing, and immune defects associated with DM. Or, the patient develops an ulcer or sustains an injury, they are unaware of it due to neuropathy, the bacteria invades the would and illicits a host response.
Risk factors -
- MRSA: hx of MRSA in past year, prevalence of MRSA over 30-50% in local area, recent hospitalization or antibiotic use in last 30 days, etc.
- Pseudomonas: soaking feet, failed non-pseudomonal antibiotics, macerated ulcer, warm climate
Bacteriology - MRSA, pseudomonas, staph, strep,
