Pulmonology Infections: Pt 1 & 2 Flashcards
Community-Acquired Pneumonia (CAP)
● Pneumonia is an acute inflammation of the lungs caused by infection
● CAP develops in people with no or limited contact with healthcare facilities or settings
● Leading cause of death in the US
and world
Most common pathogens of Community-Acquired Pneumonia (CAP)
● Streptococcus pneumoniae
● Haemophilus influenzae
● Atypical bacteria
○ Chlamydia pneumoniae
○ Mycoplasma pneumoniae
○ Legionella pneumophila
● Viruses
Common viral agents include of CAP:
● RSV
● Adenovirus
● Influenza virus
● Metapneumovirus
● Parainfluenza virus
Common fungal agents of CAP:
● Histoplasmosis
● Coccidioidomycosis
Community-Acquired Pneumonia (CAP) S/S:
● Fever, chills
● Cough
● Sputum production
● Pleuritic chest pain
● Dyspnea- generally mild and exertional
● Crackles, rales, bronchial breath sounds, egophony
● Tachypnea
● Tachycardia
● GI symptoms are common- nausea, vomiting, diarrhea
Diagnosis of CAP:
● Clinical presentation
● Chest x-ray
○ Opacities - difficult to distinguish one type from another
● Sputum testing- may include Gram stain and culture
Chest x-ray suggestive finding for CAP:
● Multilobar infiltrates suggest S. pneumoniae or Legionella pneumophila
infection
● Interstitial pneumonia (on chest x-ray- increased interstitial markings) suggests viral or mycoplasmal etiology
● Cavitating pneumonia suggests S. aureus or a fungal or mycobacterial etiology
Treatment of CAP:
● Risk stratification
○ To determine if patient should be treated as outpatient or inpatient
● Antibiotics (often empirically chosen for pts with mild to moderate risk without testing for pathogen)
● Antivirals, if needed
● Supportive measures
○ Fluids, antipyretics, analgesics, oxygen (if needed)
○ Smoking cessation counseling
Antibiotic Treatment for CAP For healthy patients, <65 years, and no recent abx use:
● Amoxicillin 1g PO three times daily x 5-7 days
Or
● Doxycycline 100 mg twice daily x 5-7 days
Alternative: Macrolides
Antibiotic Treatment for CAP
For patients with comorbidities:
● Amoxicillin-clavulanate 875/125 mg twice daily
Plus
● Macrolide (i.e., azithromycin, clarithromycin)
Or
● Doxycycline 100 mg twice daily
Failure for CAP to improve with Abx should trigger concern for:
● Nonadherence (outpatient)
● An unusual organism
● Coinfection or superinfection with a secondary organism
● Empyema
● Resistance to antimicrobial therapy
● Immunosuppression
Community-Acquired Pneumonia (CAP) Prognosis:
● Excellent for young or healthy
individuals
● Less optimistic for older, sicker people especially when caused by S. pneumoniae, Legionella, Staphylococcus aureus, or
influenza virus
Community-Acquired Pneumonia (CAP) prevention:
● Smoking cessation
● Vaccines
Healthcare-Associated Pneumonia (HCAP) has two types:
Nosocomial pneumonia:
● Hospital-associated pneumonia (HAP)
○ Occurs more than 48 hours after patients have been admitted to the hospital; excludes
infection present at the time of admission
● Ventilator-associated pneumonia (VAP)
○ Develops more than 48 hours after endotracheal intubation and mechanical ventilation
Nosocomial infections differ from
CAP in 3 ways
● Different, less common infectious causes
● Higher incidence of drug resistance
● Poor underlying health of patients
Common organisms in nosocomial pneumonias:
● Streptococcus pneumonia (often drug-resistant)
● Staphylococcus aureus (MSS and MRSA)
● Klebsiella pneumonia
● Haemophilus influenzae
● Escherichia coli
● Enterobacter species
● Pseudomonas aeruginosa
● Acinetobacter species
S/S HAP:
● Nonspecific; similar to CAP
S/S VAP:
Generally nonspecific but may
have two of the following:
● Fever
● High WBC count
● Purulent sputum
Plus chest x-ray with new or progressive opacity
Diagnosis of HAP:
● A new lung infiltrate plus clinical evidence of infection
● Arterial blood gas or pulse oximetry may help
determine severity of illness and need for
ventilation
● Sputum stain and culture - similar to CAP - not always helpful
● Bronchoscopic specimen
Hospital-Acquired Pneumonia (HAP) Treatment
Should begin antibiotic regimen quickly due to high mortality rates
Use one:
● Piperacillin-tazobactam
● Cefepime
● Levofloxacin
Treating High risk HAP:
Use one from each category:
● Cefepime
● Imipenem
● Piperacillin-tazobactam
● Aztreonam
● Ceftazidime
● Meropenem
● PLUS
○ Linezolid
○ Vancomycin
○ Telavancin
● PLUS
○ An aminoglycoside (gentamicin or tobramycin)
○ An antipseudomonal fluoroquinolone (cipro or levofloxacin)
○ A polymixin (polymixin B)
Streptococcal Pneumonia
● Caused by the Streptococcus pneumoniae bacteria
○ Gram-positive encapsulated diplococci
● Spread via airborne droplets
● Pleural effusions occur in approx 40% of patients
● Pneumococcal diseases also include otitis media, sinusitis, bacteremia, endocarditis, meningitis
○ Pneumonia being the most frequent serious infection
● Lobar pneumonia
Streptococcal Pneumonia epidemiology
● Traditionally, it has been the most common cause of CAP
○ Incidence has decreased to 5-15% probably due to the
pneumococcal vaccine and a reduction in cigarette smoking
RFs for streptococcal pneumonia
● Influenza infection
● Alcohol abuse
● Smoking
● Splenectomy
● Immunocompromised
● COPD and asthma
Streptococcal Pneumonia S/S
● Fever, chills
● Cough
○ Sputum can be “rust” colored
● Tachypnea
● Rales and bronchial breath sounds
localized at the involved lobe or site
Streptococcal Pneumonia Diagnosis
● Gram stain and culture
○ Easy to identify as lancet-shaped diplococci
○ Best seen using the Quellung test- India ink stains the capsule. May also use methylene blue stain
Streptococcal Pneumonia Treatment
● Antibiotic
○ Beta-lactam (Amoxicillin, PCN G)
○ Macrolide
○ Respiratory fluoroquinolone
Resistant strains have emerged which have made treatment difficult. May
consider later-generations of cephalosporins or combination therapy
Klebsiella Pneumonia
Caused by the Klebsiella pneumoniae bacteria, a
type of Enterobacteriaceae
● Has been associated with UTIs, pulmonary infections, bacteremia
● A rare and severe disease
● Part of the normal flora of the mouth and intestine
● Infections are usually hospital acquired
● Common among diabetics and alcoholics
Klebsiella Pneumonia
● Infections are common among those with decreased immune systems, including alcoholics, diabetics, cancer patients, patients with COPD or renal failure etc.
● Often acquired in hospitals or long-term care facilities, including
patients on ventilators
Major risk factors for klebsiella pneumonia
● Prior antibiotic use
● Use of invasive plastic devices (i.e., bladder catheters, endotracheal tubes)
Klebsiella Pneumonia S/S
● Fever, cough, increased sputum production,
increased WBC count, lung crackles,
pleuritic chest pain, dyspnea, tachypnea
○ Nonspecific bacterial pneumonia
symptoms
● Red, “currant jelly” sputum
○ Thick, mucoid and blood-tinged
sputum
Klebsiella Pneumonia diagnosis
● Confirmed by culture of
sputum or aspirated body fluid
including pleural effusion
○ Gram stain
● CXR for suspected pneumonia
● Imaging for suspected abscess
formation in the liver, spleen,
kidneys, etc
Klebsiella Pneumonia Tx
● Antibiotic choice depends on susceptibility
○ Resistance is increasing
● May drain abscesses
Staphylococcal Pneumonia
● Caused by the Staphylococcus
aureus bacteria
○ Gram-positive cocci
● A rapidly progressive disease
Staphylococcal Pneumonia epidemiology:
● In community-acquired pneumonia, it commonly affects:
○ Older adults, infants
○ Younger patients, previously healthy, recovering from influenza (post-influenza pneumonia)
■ High mortality rate
● Community-associated methicillin-resistant S. aureus (CA-MRSA) is often associated with severe necrotizing pneumonia
Staphylococcal Pneumonia S/S
● Short prodrome of fever
● Followed by respiratory symptoms, then respiratory distress
● May have GI symptoms
Diagnosis of Staphylococcal Pneumonia
● Sputum specimens are inadequate because upper respiratory tract
colonization is common
● No radiologic features are highly specific
Staphylococcal Pneumonia Treatment
● Antibiotics
○ Empiric therapy with penicillins or cephalosporins may be
inadequate because of community-associated
methicillin-resistant Staphylococcus aureus (CA-MRSA)
○ Clindamycin, trimethoprim-sulfamethoxazole (TMP-SMX), rifampin, doxycycline, or a quinolone
Legionnaires Pneumonia
● Legionnaires disease is caused by the Legionella pneumophila bacteria
○ Often present in soil and freshwater and can be transmitted through plumbing systems via freshwater sources. Outbreaks are often spread through a building’s water supply
○ The infection is usually caused by inhaling
droplets of contaminated water
Legionnaires Pneumonia S/S
● Flu-like symptoms: acute fever, chills, malaise, body aches,
headache
● May also have nausea, vomiting,
diarrhea, abdominal pain
● Pulmonary symptoms may include
dyspnea, pleuritic pain, and cough
Legionnaires Pneumonia diagnosis
● PCR testing
● Sputum culture
● Urinary antigen
● CXR may show patchy, asymmetric, progressive infiltrates, +/- pleural effusions
Legionnaires Pneumonia treatment
● Macrolides- preferably azithromycin
● Fluoroquinolones - levofloxacin
Mycoplasma Pneumonia
● Mycoplasma pneumoniae is one of the most common causes
of pneumonia, URIs, and acute bronchitis.
○ An atypical pathogen- a short rod without a cell wall, so it does not show up on Gram stains and is resistant to beta-lactams
● Typically community acquired and mild
Mycoplasma Pneumonia epidemiology
● More frequent in summer and fall
● Young adults, children
● Transmitted person to person, via
respiratory droplets
○ Epidemics are more common
among people in close quartersmilitary, university dorms etc
Mycoplasma Pneumonia S/S
● Onset is gradual
● Begins with headache, sore throat, low-grade fever, malaise (URI sxs)
● Cough (+/- sputum) follows, then chest soreness, shortness of breath (acute bronchitis)
● May also have extrapulmonary symptoms such as hemolytic
anemia, skin rashes, hepatitis
Mycoplasma Pneumonia Diagnosis
● Clinical
● CXR- patchy opacities, reticulonodular
● NAATs- Nucleic acid amplification testsdiagnostic method of choice
Treatment of Mycoplasma Pneumonia
● Empiric
○ Should target atypical and typical bacteria
● Outpatient tx- macrolide, doxycycline, or
respiratory fluoroquinolone
Mycoplasma Pneumonia Prevention
● Hand and respiratory hygiene
● Inpatient patients should be placed on droplet precautions
● No vaccination is currently available
Three most common: Fungal Pneumonia
● Pneumocystis jirovecii
● Aspergillus species (especially A. fumigatus)
● Cryptococcus neoformans
Pneumocystis pneumonia
● Pneumocystis jirovecci pneumonia (PJP)
○ Common in immunocompromised patients, especially HIV-infected
patients and those receiving systemic corticosteroids
● Transmitted by aerosol route
● Used to be called: Pneumocystis carinii pneumonia (PCP)
Pneumocystis pneumonia S/S
● Fever
● Dyspnea
● Dry, nonproductive cough
Risk Factors for Pneumocystis pneumonia
● Patients with HIV infection and CD4+ T lymphocyte counts < 200/μL
● Organ transplant recipients
● Patients with hematologic cancers
● Patients taking corticosteroids
● Advanced immunosuppression in pts not taking antiretroviral therapy
Pneumocystis pneumonia Diagnosis
● Chest x-ray
○ Often shows bilateral, diffuse perihilar infiltrates
● Pulse oximetry
○ Hypoxemia- common, even with normal CXR
○ If abnormal, consider obtaining ABGs to assess severity of hypoxemia
● Histopathologic confirmation
○ Testing done on induced sputum or bronchoscopically obtained sputum
Pneumocystis pneumonia prognosis
● Mortality for hospitalized patients is 15-20%