Pathogens, Exam 3, Upper Respiratory Tract Infections

Characterized by
• Difficulty swallowing
• Fever
• Red throat with pus patches
• Enlarged tender lymph nodes – Localized to neck

– Most patients recover uneventfully in approximately a week

– Streptococcus pyogenes
• Gram-positive
• Coccus in chains
• β hemolytic – Complete hemolysis of
red blood cells
• Commonly referred to as group A streptococcus
– Due to group A carbohydrate in cell wall
– Basis for identification from other organisms

– Causes a wide variety of illnesses
• Due to bacteria-producing enzymes and toxin that destroy cells
– Complications of infection can occur during acute illness
– Examples include scarlet fever and quinsy (peritonsilar abscess)
– Certain complications can develop late
• Acute glomerulonephritis
• Acute rheumatic fever

– Spread readily by respiratory droplets
• Especially in range of 2 to 5 feet – Nasal organism spreads more effectively than
pharyngeal carriers
• Anal carriers not common
– Dangerous source of nosocomial infections

– Peak incidence occurs in winter or spring
• Highest in grade school children

• Prevention
– No vaccine available
• New possibilities on horizon
– Adequate ventilation
– Avoid crowds
– Sore throats in presence of fever should be cultured (tested) for prompt treatment

• Treatment
– Confirmed strep throat treated with 10 days of antibiotics
• Penicillin or erythromycin are drugs of choice
– Eliminates organisms in 90% of cases