Inflammatory & Antibody Immune Responses
This type of CBC finding — elevated white blood cells, predominantly neutrophils — is what Mrs. White's labs showed and reflects the body's response to bacterial infection.
What is leukocytosis / neutrophilia (an inflammatory response)?
The minimum number of hours post-admission a patient must develop pneumonia for it to be classified as Hospital-Acquired Pneumonia (HAP).
What is 48 hours?
Given the severity and rapid development of Mrs. White's symptoms, Dr. Gilbert classified her pneumonia as this type.
What is acute (typical) pneumonia?
This is the reason vaccination is still recommended for Mrs. White even though she just recovered from a pneumococcal infection and now has some natural immunity.
What is the fact that her natural immunity is specific only to the serotype she was just infected with?
This term describes the straightforward probability of an outcome (like pneumonia) occurring in a given population, expressed as a percentage.
What is absolute risk?
This is the term for antibody coating a pathogen so that it can be recognized and engulfed by phagocytes via their Fc receptors.
What is opsonization?
Beyond the organisms involved, this is a key reason CAP and HAP require different treatment approaches — related to the host's immune status and hospital environment exposure.
What are differences in immune response/host status (often more compromised in hospitalized patients) and exposure to resistant hospital flora?
Beta-lactam monotherapy fails to treat atypical pneumonia because atypical organisms lack this target structure or replicate intracellularly.
What is a peptidoglycan cell wall?
The pneumococcal conjugate vaccine (e.g., PCV20 or PCV15 followed by PPSV23) is routinely recommended for all immunocompetent adults starting at this age.
What is age 65?
This term describes the difference in risk of an outcome between an exposed/unvaccinated group and an unexposed/vaccinated group.
What is attributable risk (risk difference)?
This class of antibody provides the main, longer-lasting, serotype-specific protection against S. pneumoniae by coating the capsule for opsonization.
What is IgG?
This classic risk factor scoring tool (acronym) utilizes Confusion, Urea, Respiratory rate, Blood pressure to determine outpatient vs. inpatient CAP management.
What is CURB-65?
This organism is a common cause of atypical pneumonia and is notably associated with exposure to water systems or cooling towers.
What is Legionella (Legionella pneumophila)?
Routine vaccination begins in _ with a pneumococcal conjugate vaccine.
What is infancy/2 months of age?
This is the formula used to calculate the number needed to treat, using the risk in the untreated/control group and the risk in the treated group.
What is NNT = 1 / (Risk in control group − Risk in treatment group), or 1 / Attributable Risk (Absolute Risk Reduction)?
This specific complement split product acts as the most potent anaphylatoxin and a powerful chemoattractant for neutrophils.
What is C5a?
This is the general difference in mortality risk between CAP and HAP, and the underlying reason for it.
What is higher mortality in HAP, largely because hospitalized patients tend to have more comorbidities, more compromised immune status, and infections with more resistant organisms?
This is a key radiographic and sputum-based difference between typical and atypical pneumonia: typical pneumonia tends to show this pattern on chest X-ray and this type of sputum, while atypical pneumonia shows the opposite of both.
What is lobar/alveolar consolidation with rust-colored sputum in typical pneumonia?
This is the approximate number of known serotypes of S. pneumoniae, which explains why vaccination cannot provide complete lifelong protection against all future infections.
What is 90 (approximately 90 serotypes)?
According to Dr. Gilbert, this is the approximate number of people who need to receive the PPSV23 vaccine in order to prevent one case of pneumonia.
What is 3,000 (roughly 1 in every 3,000 people vaccinated)?
This key acute-phase reactant is produced by hepatocytes in response to IL-6 and is commonly measured clinically to assess systemic inflammation.
What is C-reactive protein (CRP)?
A subset of HAP that develops more than 48–72 hours following intubation.
What is Ventilator-Associated Pneumonia (VAP)?
Unlike S. pneumoniae, this atypical organism lacks a cell wall entirely, which is why beta-lactam antibiotics are ineffective against it.
What is Mycoplasma pneumoniae?
Unlike polysaccharide vaccines (PPSV23), conjugate vaccines (PCV15, PCV20, PCV21) attach the polysaccharide to a carrier protein, inducing this type of immune response and memory.
What is a T-cell-dependent (or T-dependent / B-cell memory) response?
If the absolute risk of pneumonia in an unvaccinated population is 1% and the absolute risk in a vaccinated population is 0.4%, calculate the attributable risk and the resulting NNT.
What is: Attributable risk = 1% − 0.4% = 0.6% (0.006); NNT = 1 / 0.006 = approximately 167 people needed to vaccinate to prevent one case?