Infectious Disease Overview

Oral Carriage in Hospitalized Patients

• Risk factors include HIV infection, wearing dentures, diabetes, receiving antineoplastic chemotherapy, and antibiotic use.
• Children are also at increased risk for oral carriage infections.

Endogenous and Exogenous Infections

• Endogenous infections occur when commensal flora exploit opportunities to cause disease.
• Exogenous transmission can result from contaminated irrigation solutions, parenteral nutrition fluids, and medical devices like vascular pressure transducers.

Common Species of Candida

• C. glabrata is the second most common species identified in North America.
• C. parapsilosis and C. tropicalis are predominant in Latin America.

Clinical Syndromes Related to Candida Infections

• Infections can spread from superficial sites to systemic involvement, affecting multiple organs including the liver, brain, spleen, heart, and kidneys.
• Characteristic features include:
  • White patches resembling cottage cheese on mucosal surfaces.
  • Non-removable pseudomembranes that bleed when scraped.
  • Erythematous areas in the oropharynx, potentially extending to the esophagus and gastrointestinal tract.

Specific Candidal Infections

• Oral thrush: Presence of thick white patches on the oral mucosa.
• Candidal leukoplakia: White thickening of the epithelium in the mouth.
• Angular cheilitis: Sore fissures at the corners of the mouth.
• Vaginal mucosa infections are common in women.

Skin Infections Related to Candida

• Occur in moist and occluded areas such as groin, axillae, and between toes.
• Onychomycosis may develop, leading to fungal infections of the nails.
• Risk increases with recent abdominal surgery or use of indwelling catheters.

Aspergillosis

• Primary lesions occur in the lungs with potential hematogenous dissemination to heart valves and the brain.

Mucormycosis

• Caused by Mucormycotina fungi, primarily affecting immunocompromised individuals.
• Environmental fungi like Mucor spp., Rhizopus spp., and Cunninghamella spp. are culprits.
• Major risk factors include neutropenia, diabetes, steroid use, and breaches in skin integrity.
• Spores are typically transmitted via air; inhalation is the most common route of infection.

Morphology and Pathology of Mucormycosis

• Mucormycetes exhibit nonseptate hyphae, variable in width (6 to 50 µm) with frequent right-angle branching, distinguishable from Aspergillus.
• Infections commonly affect the nasal sinuses, lungs, and gastrointestinal tract.

Clinical Manifestations of Mucormycosis

• Routes of infection include inhalation, percutaneous exposure, or ingestion of spores.
• Symptoms range from localized pulmonary infections to disseminated diseases leading to severe complications such as septic shock with fever, hypotension, and acute respiratory distress.