Pharyngitis #11

Medical Microbiology Disease of the week 5

classification

Pharyngitis

causative agent

Streptococcus pyogenes

(gram positive cocci, numerous virulence factors, serotypes influence risk of complications, B-hemolytic)

epidemiology

reservoir- human skin and respiratory tract (15-20% in school kids)

portal of entry- mouth and sinuses

transmission- direct contact with infected individuals; indirect contact with inhaled droplets, contaminated food or surfaces

incubation

2-5 days

pathogenesis

colonization of tissue aided by virulence factors. protein F facilitates attachment, the capsule and M proteins inhibit phagocytosis, protein G inhibits antibody binding, and secreted enzymes damage tissue

symptoms

sore & inflamed throat and tonsils (red, swollen, sometimes pus), fever, headache, fatigue,

in children: nausea, vomiting, abdominal pain

symptoms resolve in 3-7 days

complications

scarlet fever, cellulitis, tissue damage or abscess, metastatic infection, streptococcal toxic shock syndrome, post streptococcal glomerulonephritis (inflammation in kidneys that causes damage), acute rheumatic fever

prevention

avoid crowded areas and infected individuals, practice good hygiene

treatment

antibiotics: penicillin (reduces symptoms ~1 day, but can prevent immune complications)

analgesics for pain

rheumatic fever

inflammatory lesions in heart, joints, subcutaneous tissue, and CNS; autoimmune; symptoms occur after 1-5 weeks

minor: fever, swollen and painful joints

major: carditis, arthritis, chorea, subcutaneous nodules, erythema marginatum

(untreated symptoms last 3-6 months)