Strep Throat Micr 201 Professor: Dr Hoch Carrie Matthews Joanne Nguyen 12/11/07

Taxonomy Super Kingdom:Bacteria Phylum:Firmicutes Class:Bacilli Order:Lactobacillales Family:Streptococcaceae Genus :Streptococcus Species:Streptococcus pyogenes

Streptococcus pyogenes Bacterium Group A Streptococcus. Nonmotile, non-sporeforming coccus that occurs in chains or in pairs of cells. Facultative anaerobe Requires enriched medium with blood to grow. Capsule composed of hyaluronic acid and exhibit beta-hemolysis of blood agar. Causes an array of diseases.

Virulence Factors M protein Protein F Lipoteichoic acid Hyaluronic acid capsule Invasins (streptokinase, streptodornase, hyaluronidase, and streptolysins) Exotoxins When host defenses are compromised, the organism is able to exert its virulence and causes infection.

Target Tissues Throat and tonsils. Bacteria present in nose and throat. Inflammatory process of the oropharynx and or nasopharynx.

Portals of Entry Upper respiratory tract or skin.

Ecology Part of normal microbiota. Widely distributed in human; some become asymptomatic carriers. Estimated that 5-15% of humans harbor it without signs of disease.

Pathogenesis Multiply and spread rapidly in host while evading phagocytosis and confusing the immune system.

Infection Process Spread by droplets of saliva or nasal secretions. Stimulates inflammatory response. Lysis of leukocytes and erythrocytes. An inflammatory exudate (cells and fluid) is released from blood vessels and deposited in surrounding tissue.

Symptoms Symptoms observed in 1 to 3 days. Develop red throat with white patches; red and enlarged tonsils. Trouble swallowing. Tender, swollen lymph glands on sides of neck. Fever (101˚F), pain, redness, swelling of throat and tonsils. Headache Abdominal pain. Nausea

Diagnostic Tests Rapid Antigen Detection Assay  Faster and more convenient.  Less sensitivity. Throat swab culture  High sensitivity.  Requires hours for results.  Confirms a negative RADT.

Treatments Strep throat goes away after 3-7 days with or without treatment. Doctors may prescribe an antibiotic Penicillin is the drug of choice. Erythromycin is the alternative. 70% of children are perscribed antibiotics; however, 30% have strep infections; 50% had the cold or other viral infection. Antibiotics treat bacterial infection, not viral infections. Drink enough fluids. Gargle with salt water. Get extra sleep to promote a rapid recovery.

Preventative Measures Avoid contact with those infected with strep throat. Wash hands frequently when around those with colds; viral or bacterial illnesses. Not sharing food or utensils with others. Dispose used tissues properly.

Epidemiology Race- No racial or ethnic predisposition to infection or complications is known. Sex- Both sexes are affected equally. Age- can affect persons of all ages, with a peak incidence in children aged 5-15 years. In children, GAS accounts for approximately 30% of cases of acute pharyngitis. The prevalence of GAS is significantly lower in adults, accounting for only 5-10% of cases of pharyngitis.

Morbidity & Mortality Morbidity and mortality is extremely rare, but may be due to other complications including: – Post streptococcal sequlae: Rheumatic fever and Post streptococcal glomerulonephritis (1-3% of untreated infections). – Less than.05% of Rheumatic fever is caused by streptococcal infections. – Localized purulent complications (otitis media, sinusitis, peritonsillar and retropharyngeal abscess, and suppurative cervical adenitis). – Toxic shock syndrome mortality rate over 30%. – GAS bacteremia mortality rate is 25-48%.

Latest Research Macrolide resistance in Streptococcal pharyngitis:  Studies in 2007 found that 42.6% of isolates were resistant to erythromycin; 39.6% to clindamycin. In 1997, erythromycin was considered the drug alternative.  Dirithromycin (new macrolide) is an alternative to penicillin for patients 12 years of age and older. Study done between Jan. 1, 1996 – Dec. 31, 1998 involving 208 children (ages 4-15) who had 3/more GABHS pharyngitis episodes in one yr for at least one month apart. Study to test diagnostic value of rapid antigen test. Study done comparing RADT and Throat swab culture.

References A H Abu-Sabaah, H O Ghazi. British Journal of Biomedical Science. London: Vol. 63, Iss. 4; pg. 155, 4 pgs. Antimmicrob. Agents Chemother : Center for Disease Control, Division of Bacterial and Mycotic Diseases “Group A Streptococcal (GAS) Disease”. Florence Paillard, Craig S Hill, Ronald A Blum, Linda Dearing. Medical Laboratory Observer. Montvale: Jan Vol. 36, Isss. 1; p. 10. Jennifer L St Sauver, Amy L Weaver, Laura J Orvidas, Robert M Jacobson, Steven J Jacobsen. Mayoclinic Proceedings. Rochester: Sep Vol 81, Iss. 9; pg. 1172, 5 pgs. Joanne M. Willey, Linda M. Sherwood, Christopher J. Woolverton. Microbiology. Seventh Edition. New York: McGraw-Hill, National Institute of Allery and Infection Diseases. “Group A Streptococcal Infections”. 9 Dec Sept Shuford, Gordon. “Common items carry strep threat”. 5 Dec b/strep.html&h=225&w=300&sz=8&hl=en&start=7&tbnid=doXU2QfY2fp9fM:&tbnh=87&tbnw=116&prev=. Todar, Ken “Streptococcus pyogenes”. 5 Dec “Streptococcus pyogenes” Web MD. “Strep Throat”. 5 Dec WebMD. “Strep Throat” Nov Valery Lavergne, Louise Thibault, Richard Garceau. Canadian Medical Association. Journal. Ottawa: Jul 17, Vol. 177, Iss. 2; p. 177.