Study Guide – Respiratory Infections (Chapter 22)

Immune Defense Mechanisms of the Respiratory Tract

Multiple layers of defense that prevent microbes from entering and establishing infection.

Goblet cells

Cells that secrete mucus, which traps dust, bacteria, viruses, and particles.

Mucociliary escalator

A mechanism where cilia beat upward to move trapped microbes toward the throat for expulsion.

Lysozyme

An enzyme that breaks down bacterial cell walls.

Defensins

Antimicrobial peptides that kill microbes.

Surfactant

A substance that helps reduce surface tension in the lungs; contributes to antimicrobial defense.

Secretory IgA antibodies

Antibodies that prevent microbes from attaching to mucosal surfaces.

MALT

Mucosa-associated lymphoid tissue that monitors pathogens entering the upper respiratory tract.

Alveolar macrophages

Immune cells located in the lower respiratory tract that engulf and destroy inhaled microbes.

Streptococcus pneumoniae

A bacterial pathogen that is a common cause of severe pneumonia.

Symptoms of Pneumonia

Cough, fever, chills, shortness of breath, chest pain, productive cough with sputum.

Diagnosis Clues for Pneumonia

Crackling lung sounds and white shadows on chest x-ray.

Streptococcus pneumoniae Gram Status

Gram-positive diplococci.

Klebsiella pneumoniae Gram Status

Gram-negative rod.

Mycoplasma pneumoniae Gram Status

No cell wall.

Virulence Factors of S. pneumoniae

Polysaccharide capsule that prevents phagocytosis.

PPSV23

Vaccine containing 23 serotypes for pneumonia prevention.

PCV13

Conjugated vaccine containing 13 serotypes for pneumonia prevention.

Klebsiella pneumoniae Symptoms

Similar to pneumococcal pneumonia with tissue necrosis and abscesses.

Immunocompromised Individuals

Most susceptible group for Klebsiella pneumoniae infections.

Virulence Factors of Klebsiella pneumoniae

Capsule that interferes with phagocytosis.

Mycoplasma pneumoniae Symptoms

Usually mild, with persistent cough and fatigue.

Macrolides

Antibiotics effectively used against Mycoplasma pneumoniae due to its lack of cell wall.

Streptococcus pyogenes

Bacterial pathogen known as Group A strep causing strep throat.

Symptoms of Strep Throat

Sore throat, redness, fever, pus patches.

Lancefield Groups

Grouping based on cell wall carbohydrates, with Streptococcus pyogenes as Group A.

Virulence Factor M Protein

Prevents C3b opsonization and facilitates attachment in Streptococcus pyogenes.

Risk Factors for Influenza

High-risk groups include adults over 65, children under 5, and pregnant women.

Influenza A Characteristics

Most virulent strain causing pandemics, infects humans and animals.

Antigenic Drift

Small mutations in the virus leading to seasonal outbreaks.

Two Stages of Tuberculosis

Latent TB (LTBI) which is asymptomatic and Active TB which is contagious.

MDR-TB

Multidrug-resistant tuberculosis indicating resistance to multiple antibiotics.

Symptoms of Active TB

Chronic cough, respiratory spread, systemic illness.

Pathogenesis of TB

Inhalation into lungs, engulfment by macrophages, and formation of granulomas.

Normal Microbiota of Upper Respiratory Tract

Includes Staphylococcus aureus, Streptococcus, Haemophilus, and Neisseria.

Treatment for Bacterial Pneumonia

Depends on causative agent: antibiotics for bacterial; antifungals for fungal.

Inflammation in Lungs

Caused by all bacterial pathogens leading to cough, fever, and respiratory distress.

Complications of Streptococcus pneumoniae

Septicemia, endocarditis, and meningitis if the bacteria enter the bloodstream.

Non-cell wall among bacteria

Mycoplasma pneumoniae lacks a cell wall making penicillin ineffective.

Age Group Most Susceptible to Strep Throat

Children are typically more susceptible to Streptococcus pyogenes infections.

Function of Neuraminidase

Helps the influenza virus bud out of the cell and enter new host cells.