Lecture 11- Streptococci

Question 1

How are streptococci classified?

Answer 1

By haemolysis

Question 2

Alpha haemolysis?

Answer 2

Viridans streptococci

Partial haemolysis

Streptococcus pneumoniae

Question 3

Beta haemolysis?

Answer 3

Streptococcus pyogenes

Com9lete haemolysis

Question 4

Gamma haemolysis?

Answer 4

Non haemolytic

Enterococcus faecalis

Question 5

Staph vs strep?

Answer 5

Staph is like grapes while strep is in chains

Question 6

Streptococci pos or neg

Answer 6

Gram positive (positively purple)

Gram neg would be red

Question 7

Streptococci classification schemes?

Answer 7

Lance filed, Sherman and dna sequencing analysis

Question 8

Streptococcus pyogenes?

Answer 8

Beta haemolytic lanefield group a often causing pharyngitis and tonsillitis

Question 9

What is a virulence factor?

Answer 9

Molecules produced by a bacteria that help it to colonise

Question 10

Streptococcal pharyngitis?

Answer 10

Caused by strep pyogenes.
Peak incidence 5-15 years
Droplet spread
Almost always resolves by itself antibiotics only slightly reduce course and prevent antibodies from developing

Clinical features include fever, malaise, sore throat, lymphoid hyperplasia

Question 11

What is scarlet fever?

Answer 11

Complication of streptococcal pharyngitis if infected with certain strain. Causes high fever, arthritis, jaundice and sepsis

Question 12

Supppation?

Answer 12

Pus forming

Question 13

Suppurative complications of pharyngitis?

Answer 13

Pus can move down to the lateral pharyngeal space and enter carotid artery and move to brain etc.

Peritonsillar cellulitis and retropharyngeal abscess

Question 14

Pharyngitis and acute rheumatic fever?

Answer 14

Antibodies produced against infection work against body’s own antigens.

Causes inflammation of joints, heart and CNS

Question 15

Pharyngitis and acuute post streptococcal glomerulonephritis?

Answer 15

Antibodies attack antigens in glomerulus leads to inflammation

Question 16

Strep pyogenes skin infections?

Answer 16

Impetigo

Erysipelas

Cellulitis

Necrotising fasciitis

Question 17

Cellulitis?

Answer 17

Can be caused by staph aureus or strep pyogenes. Infection of skin and subcutaneous tissue. Risk factors include IV drug use and impaired lymphatic drainage.
Treat with flucloxacillin whether the cause be aureus or pyogenes.

Question 18

Necrotising fasciitis?

Answer 18

Infection of deeper subcutaneous tissues and fascia.
Get rapid and extensive necrosis. Make incision and insert finger, if easy to move then necrotic tissue present and surgical debridement required. Causes high fever and high mortality with sudden onset

Question 19

What is streptococcal toxic shock syndrome?

Answer 19

Deep tissue infection with strep pyogenes that enters blood and causes organ failure. In 80’s tampons left in long time and caused it