Pneumonia Dr. Meg-angela Christi Amores

Definition

• • • infection of the pulmonary parenchyma often misdiagnosed, mistreated, and underestimated community-acquired pneumonia (CAP) or health care–associated pneumonia (HCAP) – hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP)

Pathophysiology

• • • • proliferation of microbial pathogens at the alveolar level and the host's response aspiration from the oropharynx inhaled as contaminated droplets hematogenous spread

Pathophysiology

• Host defense: – hairs and turbinates of the nares – branching architecture of the tracheobronchial tree traps particles on the airway lining – gag reflex and the cough mechanism – normal flora adhering to mucosal cells of the oropharynx – resident alveolar macrophages

• • host inflammatory response, rather than the proliferation of microorganisms, triggers the clinical syndrome of pneumonia inflammatory mediators, such as interleukin (IL) 1 and tumor necrosis factor (TNF), results in fever

Pathology

• • • • Edema – presence of a proteinaceous exudate Red hepatization – erythrocytes in the cellular intraalveolar exudate Gray hepatization – neutrophil is the predominant cell, fibrin deposition is abundant, and bacteria have disappeared Resolution

Etiology

• • Typical: – S. pneumoniae, Haemophilus influenzae, S. aureus and gram-negative bacilli such as Klebsiella pneumoniae and Pseudomonas aeruginosa Atypical: – Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella spp. as well as respiratory viruses such as influenza viruses, adenoviruses, and respiratory syncytial viruses (RSVs

Risk factors

• CAP:alcoholism, asthma, immunosuppression, institutionalization, and an age of 70 years versus 60–69 years

Clinical Manifestations

• • • frequently febrile, with a tachycardic response, and may have chills and/or sweats and cough pleura is involved, the patient may experience pleuritic chest pain fatigue, headache, myalgias, and arthralgias • Crackles, bronchial breath sounds

Management

• Diagnosis – CLINICAL – XRAY – suggests etiology • pneumatoceles suggest infection with S. Aureus • upper-lobe cavitating lesion suggests tuberculosis – Sputum Gram stain and culture – Blood culture

Management

• Treatment : CAP – Site of Care • Home • Hospital – Antibiotics • Empiric • Previously healthy and no antibiotics in past 3 months • A macrolide [clarithromycin (500 mg PO bid) or azithromycin (500 mg PO once, then 250 mg od)] or Doxycycline (100 mg PO bid)