Group B Streptococci Flashcards
What are examples of Group B streptococci?
- Strep Virdans
2. Strep agalactiae
Characteristics of Streptococci virdans?
Gram positive cocci in pairs or chains
part of human flora
catalase negative
Facultative anaerobes
Optochin resistant organism?
Strep. Viridans
Optochin sensitive organism?
Strep. Penumoniae
Bile resistant organism?
Enterococcus (group d)
Bacitracin resistant organism?
Strep. agalactiae (group b)
Bacitracin sensitive organism?
Strep. Pyogenes
Microbiological properties of Strep. agalactiae?
- Gram positive, cocci
- encapsulated
- Group B lancefield antigen
- CAMP test positive
Which organisms are B-hemolytic?
Strep. Pyogenes and Strep. Agalactiae
Which organism is Gamma-hemolytic?
Enterococcus
Which organisms are Alpha-hemolytic?
Strep. pneumonia and Strep. Viridans
Strep Viridans includes what organisms?
Strep. mutans, songuis, milleri, mitis
What is the most important VF of Strep. Agalactiae?
Capsule is imp. VF
What capsule types are associated with early onset neonatal disease?
Type 1a, III and V
Which capsule is commonly associated with Late onset disease?
Type III
Which capsule types are most common in adults?
1a and V
Which toxin from Strep. Agalactiae is toxic to neutrophils?
CylE pre forming toxin
What is the epidemiology of Strep. Agalactiae?
- Most common cause of septicemia and meningitis in newborns.
- 25% of pregnant women have Group B Strep (GBS) in vagina or rectum
Presence of GBS between what weeks of gestation are of most concern?
Weeks 35-37
What are the stages of neonatal infection?
- Colonization of pregnant mother
- Ascending placental and Uterine infection
- Pneumonia/Lung injury
- Bacteremia and Sepsis syndrome
- BBB penetration and meningitis
Strep. Agalactiae infections in pregnant women results in what?
- Postpartum endometritis
- Wound infection
- UTI
Strep Agalactiae lab diagnosis to detect vaginal carriage in pregnant women?
PCR-based assays
What tests do you use to identify Isolates?
Positive CAMP test
Hippurate hydrolysis
The CAMP test examines what?
examines interaction of presumptive GBS with S.aureus in co-culture.
A positive CAMP test is indicated by what?
Enhanced hemolysis closest to S. aureus (characteristic arrowhead pattern)
GBS enhances S.aureus hemolysis how?
by secreting diffusible CAMP factor
What is the drug of choice for GBS?
Penicillin
What drugs can you use to serious infections with GBS?
Ampicillin with an aminoglycosides or a cephalosporin
If patient is allergic to penicillin or ampicillin what can you give to a patient who has GBS?
Clindamycin or vancomycin
For high risk babies, what is given to the mothers before delivery?
Penicillin is given to mother 4 hours before delivery
Strep. mutans and Strep. sanguis are found where?
Commensal found in oral cavity, GIT and genitourinary tract
characteristics of Strep. mutans and Strep. sanguis?
- Gram positive cocci chain
- Indistinguishable from S. pyogenes in gram smear.
- Optochin resistant
- Nosocomial (hospital acquired)
Pathogenesis of Strep. mutans and sanguis?
S. mutans Dextran mediated adherence glue the oral flora onto the tooth enamel or damaged heart valve and to each other (vegetation)
What are the diseases Strep. mutans and sanguis causes?
- Native valve subacute bacterial endocarditis
2. Dental caries (tooth decay)
What are the clinical manifestations of Native valve subacute bacterial endocarditic?
Murmur, anorexia, night sweats, weight loss, etc.
RANDOM!!
what causes acute bacterial endocarditis? what causes prosthetic valve endocarditis?
Staph. Aureus
Staph. Epidermidis
What is the treatment for Strep. mutans and sanguis?
Penicillin G with aminoglycosides for endocarditis.
