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)