CAP Flashcards
Phases in lobar pneumococcal pneumonia
Edema (Congestion)
Red Hepatization
Gray Hepatization
Resolution (Final phase)
Initial phase w/ the presence of proteinaceous exudate and bacteria in the alveoli
rarely evident in clinical or autopsy specimens because of the rapid transition to the next phase
EDEMA
presence of ERYTHROCYTES in the cellular intraalveolar exudate
neutrophils influx - more important with regard to host defense
bacteria are occasionally seen in pathologic specimens collected during this phase
RED HEPATIZATION
no new erythrocytes are extravasating and those already present have been lysed and degraded
NEUTROPHILS - predominant cells
abundant fibrin deposition
(-) bacteria
corresponds with SUCCESSFUL CONTAINMENT OF THE INFECTION and IMPROVEMENT IN GAS EXCHANGE
GRAY HEPATIZATION
final phase
MACROPHAGE reappears as the dominant cell type in the alveolar space, and the debris of neutrophils, bacteria, and fibrin has been cleared, as has the inflammatory response
RESOLUTION
MC pattern in nosocomial pneumonias
bronchopneumonia pattern
TYPICAL BACTERIAL PATHOGENS (CAP)
• S. pneumoniae
• Haemophilus influenzae
• S. aureus
• gram- (-) bacilli - Klebsiella pneumoniae and Pseudomonas aeruginosa
ATYPICAL BACTERIAL PATHOGENS
Chlamydia pneumoniae
Legionella species (in inpatients)
Mycoplasma pneumoniae
respiratory viruses - influenza viruses, adenoviruses, human metapneumovirus, and respiratory syncytial viruses
Play a significant role only when an episode of aspiration has occurred days to weeks before presentation of pneumonia
Anaerobes
MCC of CAP
Strep pneumoniae
complicate influenza infection
S. aureus pneumonia
RISK FACTORS FOR CAP:
• alcoholism
• asthma
• immunosuppression
• institutionalization
• age of ≥70 years
RISK FACTORS FOR PNEUMOCOCCAL PNEUMONIA:
• dementia
• seizure disorders
• heart failure
• cerebrovascular disease (CVD)
• alcoholism
• tobacco smoking
• chronic obstructive pulmonary disease (COPD)
• HIV infection
more likely in patients with skin colonization or infection with CA-MRSA
CA-MRSA pneumonia
Tend to infect patients who have RECENTLY BEEN HOSPITALIZED and/or RECEIVED ANTIBIOTIC THERAPY or who have comorbidities such as alcoholism, heart failure, or renal failure
Enterobacteriaceae
Particular problem in patients with SEVERE STRUCTURAL LUNG DISEASE, such as bronchiectasis, cystic fibrosis, or severe chronic obstructive pulmonary disease (COPD)
P. aeruginosa
RISK FACTORS FOR LEGIONELLA INFECTION:
• diabetes
• hematologic malignancy
• cancer
• severe renal disease
• HIV infection
• smoking
• male gender
• recent hotel stay or ship cruise
CLINICAL MANIFESTATIONS of CAP
• febrile with tachycardia
• cough - either nonproductive or productive of mucoid, purulent, or blood-tinged sputum
• gross hemoptysis - suggestive of CA-MRSA pneumonia
• involvement of the pleura pleuritic chest pain
• 20% of patients - GI symptoms such as nausea, vomiting, and/or diarrhea
• OTHER SYMPTOMS - fatigue, headache, myalgias, and arthralgias
• ↑ respiratory rate and use of accessory muscles of respiration – common
CLINICAL MANIFESTATIONS of CAP
• febrile with tachycardia
• cough - either nonproductive or productive of mucoid, purulent, or blood-tinged sputum
• gross hemoptysis - suggestive of CA-MRSA pneumonia
• involvement of the pleura –> pleuritic chest pain
• 20% of patients - GI symptoms such as nausea, vomiting, and/or diarrhea
• OTHER SYMPTOMS - fatigue, headache, myalgias, and arthralgias
• ↑ respiratory rate and use of accessory muscles of respiration – common
PE findings in CAP
• PALPATION - ↑ or ↓ TACTILE FREMITUS
• PERCUSSION - can vary from DULL to flat, reflecting underlying consolidated lung and pleural fluid, respectively
• AUSCULTATION - CRACKLES, BRONCHIAL BREATH SOUNDS, and PLEURAL FRICTION RUB (possible)
DIFFERENTIAL DIAGNOSIS INCLUDES BOTH INFECTIOUS AND NONINFECTIOUS ENTITIES:
acute bronchitis
acute exacerbations of chronic bronchitis
heart failure
pulmonary embolism
hypersensitivity pneumonitis
radiation pneumonitis
often necessary to differentiate CAP from other conditions
Chest radiography
often necessary to differentiate CAP from other conditions
Chest radiography
pneumatoceles - suggest infection with S. aureus
upper-lobe cavitating lesion - suggests tuberculosis
May be of value in a patient with SUSPECTED POSTOBSTRUCTIVE PNEUMONIA caused by a tumor or foreign body or suspected cavitary disease
CT
specific views of chest radiograph should be requested?
Standing PA and LATERAL views of the chest in full inspiration comprise the best radiologic evaluation of a patient suspected of having pneumonia. (Grade A)
Sputum Gram Stain and Culture
sputum sample:
> 25 neutrophils/LPF
<10 squamous epithelial cells/LPF
The standard for diagnosis of respiratory viral infection
PCR of nasopharyngeal swabs
CURB-65 criteria - severity-of-illness score
Confusion
Urea >7 mmol/L
Respiratory rate ≥30/min
Blood pressure - systolic ≤90 mmHg/ diastolic ≤60 mmHg
Age ≥65 years
score of 0 - among whom the 30-day mortality rate is 1.5% - can be treated outside the hospital
score of 2 - the 30-day mortality rate is 9.2%, and patients should be admitted to the hospital
0-1 - treat as outpatient
2 - admit patient
>3 - consider ICU admission
Response to therapy is expected w/ 24-72 hrs of initiating treatment
fever decreases w/n 72 hrs
temp normalizes w/n 5 days
respiratory signs (tachypnea) return to normal
MINIMAL INHIBITORY CONCENTRATION (MIC) CUTOFFS FOR PENICILLIN IN PNEUMONIA
≤2 μg/mL - susceptibility
> 2–4 μg/mL - intermediate
≥8 μg/mL- resistant
RISK FACTORS FOR PENICILLIN-RESISTANT PNEUMOCOCCAL INFECTION:
recent antimicrobial therapy
age of <2 years or >65 years
attendance at day-care centers
recent hospitalization
HIV infection
The most important risk factor for antibiotic-resistant pneumococcal infection
use of a specific antibiotic w/n the previous 3 months
Previously healthy and no antibiotics in past 3 mos
macrolide
CLARITHROMYCIN 500 mg PO BID
OR
AZITHROMYCIN 500 mg PO once then 250 mg qd
OR
DOXYCYCLINE 100 mg PO BID
Comorbidities or antibiotics in past 3 mos: select an alternative from a different class
respiratory fluoroquinolone
MOXIFLOXACIN 400 mg PO qd
GEMIFLOXACIN 320 mg PO qd
LEVOFLOXACIN 750 mg PO qd
OR
beta lactam
preferred
high dose AMOXICILLIN 1 g TID
OR
AMOXICILLIN/CLAVULANATE 2 g BID
alternatives
CEFTRIAXONE 1-2g IV qd
CEFPODOXIME 2OO mg PO bid OR
CEFUROXIME 500 mg PO bid PLUS a macrolide
Inpatients, NON- ICU
respiratory fluoroquinolone
MOXIFLOXACIN 400 mg PO or IV qd
LEVOFLOXACIN 750 mg PO or IV qd
beta lactam
CEFTRIAXONE 1-2g IV qd
AMPICILLIN 1-2 g IV q4-q6
CEFOTAXIME 1-2 g q8h
ERTAPENEM 1 g IV qd
PLUS
macrolide
ORAL CLARITHROMYCIN or AZITHROMYCIN or IV AZITHROMYCIN once, then 500 mg qd
Inpatients, ICU
beta lactam
CEFTRIAXONE 2 g IV qd
AMPICILLIN-SULBACTAM 2 g IV q8h
OR
CEFOTAXIME 1-2 g IV q8h
PLUS
either AZITHROMYCIN or a FLUOROQUINOLONE
If Pseudomonas is a consideration
*antipseudomonal beta lactam
PIPERACILLIN/TAZOBACTAM 4.5 g IVq6h
CEFEPIME 1-2 g IV q12h
IMIPENEM 500 mg IV q6h
MEROPENEM 1 g IV q8h
PLUS
either
CIPROFLOXACIN 400 mg IV q12h
OR
LEVOFLOXACIN 750 mg IV qd
*above beta lactam PLUS an aminoglycoside AMIKACIN 15 mg/kg qd
OR
TOBRAMYCIN 1.7 mg/kg qd
PLUS
AZITHROMYCIN
*above beta lactams PLUS aminoglycoside PLUS and antipneumococcal fluoroquinolone
If CA-MRSA is a consideration
ADD LINEZOLID 600 mg IV q12h
OR
VANCOMYCIN 15 mg/kg q12 h initiall w/ adjusted dose
PLUS
CLINDMYCIN 300 mg q6h
Discharge Criteria
during the 24 hrs before discharge
temp 36-37.5
pulse <100/min
RR 16-25/min
SBP >90 mmHg
blood O2 saturation >90%
functioning GIT (allowing use of oral antibiotics)
