PNEUMONIA Flashcards
Risk Factors for Pathogens Resistant to Usual Therapy for CAP.
- Hospitalization 2 or more days in previous 90 days
- Use of antibiotics in previous 90 days
- Immunosuppresion
- Nonambulatory status
- Tube feedings
- Gastric acid suppression
- Severe COPD or bronchiectasis
Multidrug-resistant gram-negative bacteria and MRSA
Risk Factors for Pathogens Resistant to Usual Therapy for CAP.
- Cavity infiltrate or necrosis
- Gross hemptysis
- Erythematous rash
- Concurrent influenza
- Young, previously healthy status
- Summer-month onset
CA-MRSA
Risk Factors for Pathogens Resistant to Usual Therapy for CAP.
- Hospitalization 2 or more days in previous 90 days
- Use of antibiotics in previous 90 days
- Chronic hemodialysis in previous 30 days
- Documented prior MRSA colonization
- Congestive heart failure
- Gastric acid suppression
Nosocomial MRSA
Mechanical Factors of CAP
- hair and turbinates of the nares
- branching architecture of the tracheobronchial tree
- gag and cough reflex
- normal flora adhering to mucosal cells of the oropharynx
Microorganisms access to the lower respiratory tract by:
– microaspiration from the oropharynx
– small-volume aspiration occurs frequently during sleep
– hematogenous spread
– contiguous extension from an infected pleural or mediastinal space
When the capacity of the alveolar macrophages to ingest or kill the microorganisms is exceeded this become manifested.
clinical pneumonia
Host inflammatory response trigger the clinical syndrome of pneumonia
– release of inflammatory mediators (IL6 and TNF)
fever
host inflammatory response trigger the clinical syndrome of pneumonia
- chemokines (IL 8 and GCSF) -> release of neutrophils
peripheral leukocytosis and increased purulent secretions
Host inflammatory response trigger the clinical syndrome of pneumonia
- Inflammatory mediators released by macrophages and the newly recruited neutrophils
alveolar capillary leak
Host inflammatory response trigger the clinical syndrome of pneumonia
- erythrocytes cross the alveolar–capillary membrane
hemoptysis
Host inflammatory response trigger the clinical syndrome of pneumonia
- capillary leak
radiographic infiltrate and rales
Host inflammatory response trigger the clinical syndrome of pneumonia
- alveolar filling
hypoxemia
Host inflammatory response trigger the clinical syndrome of pneumonia
- increased respiratory drive in the systemic inflammatory response syndrome
respiratory alkalosis
– presence of erythrocytes in the cellular intra-alveolar exudate
– neutrophil influx is more important with regard to host defense
– bacteria are occasionally seen in pathologic specimens collected during this phase
Red hepatization phase
– no new erythrocytes are extravasating, and those already present have been lysed and degraded
– neutrophil is the predominant cell, fibrin deposition is abundant, and bacteria have disappeared
– corresponds with successful containment of the infection and improvement in gas exchange
Gray hepatization
- presence of a proteinaceous exudate—and often of bacteria—in the alveoli
Edema
– macrophage reappears as the dominant cell type in the alveolar space
– debris of neutrophils, bacteria, and fibrin has been cleared, as has the inflammatory
response
Resolution
Most common etiology of CAP
Streptococcus pneumoniae
Atypical pathogens
– Mycoplasma pneumoniae,
– Chlamydia pneumoniae
– Legionella species
– respiratory viruses
- play a significant role only when an episode of aspiration has occurred days to weeks before presentation for pneumonia
- Risk factors: unprotected airway (in patients with alcohol or drug overdose or a seizure disorder) and significant gingivitis
Anaerobes
Clinical Manifestation of CAP involving palpitation.
increased or decreased tactile fremitus
Clinical Manifestation of CAP involving percussion.
dull to flat
Clinical Manifestation of CAP involving auscultation
crackles, bronchial breath sounds, and possibly a pleural friction rub
In chest x-ray of CAP, pneumatoceles suggest infection with
S. aureus
In chest x-ray of CAP, upper-lobe cavitating lesion suggest
tuberculosis
Adequate sputum sample for Gram Stain and Sputum Culture of CAP
> 25 neutrophils and <10 squamous epithelial cells per LPF
For CAP patient’s admitted to the ICU and intubated, a ______ has a high yield on culture
deep suction aspirate or bronchoalveolar lavage sample
Most frequently isolated pathogen in Blood Culture for CAP
S. Pneumoniae
No longer considered de rigueur for all hospitalized CAP patients
BLOOD CULTURES
■ Test for Legionella pneumophila detects only serogroup 1
■ Legionella urine antigen test: 70% sensitivity and 99% specificity
■ Pneumococcal urine antigen test: 70% sensitivity > 90% specificity
URINARY ANTIGEN TESTS
- Tests amplify a microorganism’s DNA or RNA.
- Detect the nucleic acid of Legionella species, M. pneumoniae, C. pneumoniae, and mycobacteria
- Increased bacterial load documented in whole blood by this test is associated with an increased risk of septic shock, the need for mechanical ventilator, and death
POLYMERASE CHAIN REACTION
has become the standard for diagnosis of respiratory
viral infection
PCR of nasopharyngeal swabs
■ Fourfold rise in specific IgM antibody titer between acute- and convalescent-phase
serum samples
■ Fallen out of favor because of the time required to obtain a final result
SEROLOGY
– identification of worsening disease or treatment failure
C reactive protein
– distinguishing bacterial from viral infection
– determining the need for antibacterial therapy
– deciding when to discontinue treatment
Procalcitonin
Acquired by direct DNA incorporation and remodeling resulting from contact with closely related oral commensal bacteria, by the process of natural transformation, or by mutation of certain genes
S. Pneumoniae Antibiotic Resistance
minimal inhibitory concentration (MIC) cutoffs for penicillin in S. pneumoniae pneumonia:
■ ≤2 µg/mL for susceptible
■ >2–4 µg/mL for intermediate
■ ≥8 µg/mL for resistant
Risk factors for penicillin-resistant pneumococcal infection for S. pneumoniae:
- antimicrobial therapy,
- age of <2 years or >65 years,
- attendance at day-care centers,
- recent hospitalization, and
- HIV infection
Methicillin resistance in S. aureus is determined by the ____, which encodes for resistance to all β-lactam drugs
mecA gene
____ resistance to macrolides is increasing as a result of binding-site mutation in domain V of 23S rRNA
Mycoplasma
____species are typically resis- tant to cephalosporins, and the drugs of choice for use against these organisms are usually fluoroquinolones or carbapenems.
Gram-negative Bacilli
– Enterobacter
Initial Tx Strategies for Outpx with CAP
STATUS: No comorbidities or risk factors for antibiotic resistance
Combination Therapy: Amoxicilin + macrolide or doxycycline
or
Monotherapy: Doxycycline or macrolide
Initial Tx Strategies for Outpx with CAP
STATUS: With comorbidities w/ or w/o risk factors for antibiotic resistance
Combination Therapy: amoxicilin/clavulanate or sephalosporin + either macrolide or doxycycline
or
Monotherapy with a respiratory fluoroquinolone
Initial Tx for Inpx w/ or w/o risk factors for infection w/ MRSA or P. aeuroginosa
DISEASE SEVERITY, RISK STATUS: Non-severe
No risk factors
Beta lactam + macrolide
or
respiratory fluoroquinoline
Initial Tx for Inpx w/ or w/o risk factors for infection w/ MRSA or P. aeuroginosa
DISEASE SEVERITY, RISK STATUS: Nonsevere
Prior respiratory isolation
Add coverage for MRSA
Initial Tx for Inpx w/ or w/o risk factors for infection w/ MRSA or P. aeuroginosa
DISEASE SEVERITY, RISK STATUS: Nonsevere
Recent hospitalization, antibiotic tx w/ or w/o LV
Add coverage for MRSA only if cultures are positive
Initial Tx for Inpx w/ or w/o risk factors for infection w/ MRSA or P. aeuroginosa
DISEASE SEVERITY, RISK STATUS: SEVERE
No risk factors
Beta lactam + macrolide
or
beta lactam + respiratory fluoroquinolone
Initial Tx for Inpx w/ or w/o risk factors for infection w/ MRSA or P. aeuroginosa
DISEASE SEVERITY, RISK STATUS: SEVERE
Prior respiratory isolation
Add coverage for MRSA
Initial Tx for Inpx w/ or w/o risk factors for infection w/ MRSA or P. aeuroginosa
DISEASE SEVERITY, RISK STATUS: SEVERE
Recent hospitalization, antibiotic tx w/ or w/o LV
Add coverage for MRSA
