Group B Strep Treatment and Structure

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Questions and Answers

Which gene is commonly associated with high resistance to vancomycin?

VanA (correct)

VanC

VanX

VanB

What type of bacteria is identified as aerobic among the common isolates?

G.haemolysans (correct)

G.morbillorum

Lactococcus

VanC

What is the result of placing streptococci into a dilute acid solution and heating for 10 minutes?

Improved antibiotic susceptibility

Enhanced growth

Change in Gram staining results (correct)

Increased virulence

Which biochemical test is positive for the common isolates mentioned?

PYR Signup and view all the answers

What is the typical appearance of bacteria that decolorize easily during Gram staining?

Gram-negative cocci Signup and view all the answers

Which treatment is considered the drug of choice for Luke’s condition?

Penicillin Signup and view all the answers

What is the purpose of intrapartum prophylaxis during treatment?

To reduce the incidence of sepsis in infants Signup and view all the answers

In life-threatening cases, which treatment is recommended alongside Penicillin?

Aminoglycosides Signup and view all the answers

Which antibiotic is NOT mentioned as part of the treatment options for Luke's condition?

Clindamycin Signup and view all the answers

What condition can prophylactic treatment prevent, but not glomerulonephritis?

Rheumatic fever Signup and view all the answers

What type of antigen is possessed by pregnant women that indicates the presence of Group B Streptococci?

Acid-stable polysaccharide antigen Signup and view all the answers

Which method is used to collect samples from pregnant women to check for GBS?

Vaginal and rectal swab Signup and view all the answers

What do the three major serotypes of Group B Streptococci include?

IA, IB, II Signup and view all the answers

What is the effect of the capsular polysaccharide from Group B Streptococci on the immune system?

Inhibits the activation of alternative complement pathway Signup and view all the answers

Which medium is used for inoculating GBS samples for incubation?

Todd Hewitt Broth with antimicrobials Signup and view all the answers

What antibiotics are present in Lim Broth used for GBS culture?

Colistin and Nalidixic acid Signup and view all the answers

Why is the presence of sialic acid significant in Group B Streptococci serotypes?

It indicates polysaccharide encapsulation Signup and view all the answers

What is the purpose of TransVag Broth with Gentamicin and Nalidixic acid?

For the enrichment of GBS Signup and view all the answers

What is the primary pathogenic staphylococcus associated with human infections?

Staphylococcus aureus Signup and view all the answers

Which test is used to detect acetoin production from glucose?

Voges-Proskauer Test Signup and view all the answers

What type of bacteria is categorized as coagulase negative?

Staphylococcus epidermidis Signup and view all the answers

Which characteristic is true about staphylococci?

They are spherical and form grape-like clusters. Signup and view all the answers

What is a significant factor that leads coagulase negative staphylococci to cause infections?

They possess slime factors. Signup and view all the answers

Which of the following is a common infection associated with Staphylococcus saprophyticus?

Urinary tract infections Signup and view all the answers

What distinguishes staphylococci from streptococci in terms of their arrangement?

Staphylococci form grape-like clusters. Signup and view all the answers

A major extracellular factor produced by staphylococci is which of the following?

Hemolysin Signup and view all the answers

What is the purpose of the Rapid CAMP test?

To detect enhanced hemolysis between staphylococci and streptococci. Signup and view all the answers

What does a positive result in the Hippurate Hydrolysis Test indicate?

The hydrolysis of sodium Hippurate. Signup and view all the answers

Which of the following tests can differentiate Group B streptococci from other β-hemolytic streptococci?

Hippurate Hydrolysis Test Signup and view all the answers

What is the primary drug of choice for susceptibility testing of streptococci?

Penicillin Signup and view all the answers

What does the L-Pyrrolidonyl-a-Naphthylamide Hydrolysis (PYR) test identify?

Presence of PYR-positive species. Signup and view all the answers

Which method uses bile salts for cell wall lysis in S. pneumoniae identification?

Bile Solubility Test Signup and view all the answers

What does a red result after adding DMACA reagent in the LAP test indicate?

Positive hydrolysis of leucine. Signup and view all the answers

What is the expected outcome of using B-lysin on Group B streptococci?

Classical arrow-shaped hemolysis. Signup and view all the answers

Which of the following describes the primary limitation of nucleic acid probes?

Higher cost compared to other tests. Signup and view all the answers

What is indicated by the presence of multi-drug resistant strains in streptococci?

Potential treatment challenges. Signup and view all the answers

What does the detection of the autocatalytic enzyme amidase signify in the context of S. pneumoniae?

Identification using Bile Solubility Test. Signup and view all the answers

What enhances the specificity of real-time PCR compared to traditional methods?

Detection of specific gene targets. Signup and view all the answers

Which of the following immunoassays is commonly used for agglutination testing?

Latex agglutination Signup and view all the answers

In the context of identifying Streptococcus pyogenes, how is the PYR test utilized?

To presumptively identify the species. Signup and view all the answers

What does a 16mm diameter with a 10-mm disk indicate in a susceptibility test using B-lysin?

Sensitivity to B-lysin. Signup and view all the answers

Study Notes

Treatment for Group B Strep

Dean Version: Ampicillin, with or without an aminoglycoside.
ANGELO Version:
- Penicillin and Ampicillin (most strains sensitive to these drugs)
- Penicillin + Ampicillin with Aminoglycosides (used in life-threatening cases or pregnant carriers)
- Intrapartum prophylaxis and selective antibiotic administration to infants (reduces risk of sepsis in newborns by 90%)
- Ceftriaxone or Cefotaxime

Group B Strep (GBS) Antigen Structure

Possess the Group B specific antigen.
Acid-stable polysaccharide found in the cell wall.
Also known as Group B Streptococci.
Nine recognized capsular polysaccharide serotypes.
Three major serotypes: IA, IB, II.
Contain a terminal residue of sialic acid.
Weakly immunogenic and can inhibit activation of the alternative complement pathway.

GBS Specimen Collection and Handling

Pregnant Women:
- Collect vaginal and rectal swab material between weeks 35-37 of gestation to check for GBS presence.
- Inoculate the swab into a suitable medium and incubate for 18-24 hours.
- Culture in:
  - Todd Hewitt Broth with antimicrobials (Lim Broth): contains 10 ug/mL of Colistin and 15 ug/mL Nalidixic acid
  - TransVag Broth with 8 ug/mL Gentamicin and 15 ug/mL Nalidixic acid

GBS Culture Media

Strep B Carrot Broth: enrichment chromogenic medium for isolating GBS.
Vancomycin-containing agar and chromogenic VRE media: used for screening for vancomycin resistance.
PCR-based assays: can be used for identification of GBS.

Vancomycin Resistance

Eight phenotypes of vancomycin resistance have been identified.
VanA and VanB are the most commonly encountered.
VanA is highly resistant to vancomycin and is located in plasmids and transposons.

Large Colony Isolates

S.dysgalactiae, subsp.sanguinis
Common Isolates: G.haemolysans (Aerobic) and G.morbillorum (Anaerobic)

Staphylococcus

Gram-positive, catalase positive.
Spherical, non-motile, bacteria that form in grape-like clusters (streptococci form in chains).
No capsule, non-spore former.
Belong to the Staphylococcaceae family.
Aerobic and facultative anaerobic.

Coagulase Positive Staphylococci

S.aureus – major human pathogen.
S.delphini, S.intermedius, S.hyicus, S.shleiferi – found in animals.

Coagulase Negative Staphylococci (CONS)

S.epidermidis – cause of hospital-acquired infections.
S.saphrophyticus – causes urinary tract infections in sexually active young females.

Extracellular Factors (Cytolytic Toxins)

Cytolysin or Hemolysin: cytotoxic toxins including hemolysins, leukocidins, exfoliatins, and enterotoxins.

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Description

This quiz covers the treatment protocols for Group B Streptococcus, focusing on the use of antibiotics such as Ampicillin and Penicillin. Additionally, it explores the antigen structure of GBS and best practices for specimen collection in pregnant women to prevent sepsis in newborns. Test your knowledge on these critical aspects of maternal and infant healthcare.