Podcast
Questions and Answers
Streptococcus and Enterococcus are classified based solely on biochemical tests.
Streptococcus and Enterococcus are classified based solely on biochemical tests.
False
Streptococcus has over 100 species while Enterococcus has over 54 species.
Streptococcus has over 100 species while Enterococcus has over 54 species.
True
All species of Streptococcus are haemolytic.
All species of Streptococcus are haemolytic.
False
The common causes of human streptococcal infections belong to Lancefield groups A, B, and C.
The common causes of human streptococcal infections belong to Lancefield groups A, B, and C.
Signup and view all the answers
Enterococcus was formerly classified as Group D Streptococcus.
Enterococcus was formerly classified as Group D Streptococcus.
Signup and view all the answers
Streptococcus species are catalase positive and motile.
Streptococcus species are catalase positive and motile.
Signup and view all the answers
The 13-valent conjugated pneumococcal vaccine is recommended for adults over 2 years old.
The 13-valent conjugated pneumococcal vaccine is recommended for adults over 2 years old.
Signup and view all the answers
Enterococcus species require enriched media for growth.
Enterococcus species require enriched media for growth.
Signup and view all the answers
Vaccines are generally effective in patients with asplenia.
Vaccines are generally effective in patients with asplenia.
Signup and view all the answers
β-Haemolytic streptococci are characterized as gram-negative and bacilli.
β-Haemolytic streptococci are characterized as gram-negative and bacilli.
Signup and view all the answers
Group C and G Streptococci can cause pharyngitis.
Group C and G Streptococci can cause pharyngitis.
Signup and view all the answers
The anginosus group of β-haemolytic streptococci can lack group-specific antigens.
The anginosus group of β-haemolytic streptococci can lack group-specific antigens.
Signup and view all the answers
Streptococcus pneumoniae is a common cause of bacterial pneumonia in individuals over 50 years and those with impaired defense mechanisms.
Streptococcus pneumoniae is a common cause of bacterial pneumonia in individuals over 50 years and those with impaired defense mechanisms.
Signup and view all the answers
Pyrrolidonyl arylamidase (PYR) test is positive for β-haemolytic streptococci.
Pyrrolidonyl arylamidase (PYR) test is positive for β-haemolytic streptococci.
Signup and view all the answers
β-haemolytic streptococci can produce colonies on blood agar that are small and white.
β-haemolytic streptococci can produce colonies on blood agar that are small and white.
Signup and view all the answers
The majority of early-onset infections occur within the first week of life.
The majority of early-onset infections occur within the first week of life.
Signup and view all the answers
Study Notes
Streptococcus and Enterococcus Overview
- Greek origin of "Streptus" means easily bent or twisted, reflecting the bacterial arrangement.
- Classified under families Streptococcaceae (Streptococcus) and Enterococcaceae (Enterococcus).
- Classification is based on serological (Lancefield) typing, hemolysis patterns on blood agar (BA), and biochemical tests.
General Characteristics
- Both genera consist of Gram-positive cocci, often found in pairs or chains consisting of 3-30 cells.
- Size ranges from 0.5 to 2 µm and are facultative anaerobes; some can thrive in elevated CO2 conditions.
- Growth requires enriched media, with exceptions for non-fastidious Enterococcus, and optimal incubation temperature at 35-37°C.
- Hemolysis can be α (partial), β (complete), or γ (non-hemolytic), with colonies exhibiting varying morphology.
- All species are catalase negative, fermentative, non-spore forming, and non-motile.
Streptococcal Infections
- Most common infections are caused by Group A (S. pyogenes), Group B (S. agalactiae), and Group C streptococci.
- Rare infections involve Groups E, F, G, and L, which contain diverse streptococcal species.
- Group D encompasses the Enterococcus genus, previously categorized under Streptococcus.
β-Hemolytic Streptococci Characteristics
- β-hemolytic streptococci appear as Gram-positive cocci in chains, 1-2 µm in diameter, capable of producing β-hemolytic colonies on blood agar.
- Yield white, convex colonies sizes between ≤1-2 mm; typically catalase negative.
- Bacitracin susceptibility varies, with some being resistant.
- Pyrrolidonyl arylamidase (PYR) test results are variable across Lancefield groups.
Significant Species in β-Hemolytic Groups
- Group A: S. pyogenes (large colonies), Anginosus group (small colonies).
- Group B: S. agalactiae (large colonies).
- Group C: S. dysgalactiae subsp. equisimilis (both large and small colonies), Anginosus group.
- Group F: Anginosus group (small colonies).
- Group G: S. dysgalactiae subsp. equisimilis (large), Anginosus group (small colonies).
- Nongroupable species: frequently small colonies from the Anginosus group.
Clinical Considerations
- Early onset of Streptococcus infections can present as respiratory distress, fever, lethargy, and hypotension in neonates.
- Late-onset infections may occur 7 days to 3 months post-birth.
- Group C and G streptococci can cause pharyngitis and are common bacterial pneumonia agents in children under 5 years and individuals over 50 or with weakened defenses.
- Clinical pneumonia characteristics include sudden onset, chills, high fever, coughing (pink to rusty sputum), and pleuritic chest pain.
Vaccination
- The 13-valent conjugated pneumococcal vaccine is recommended for infants under 2 years and administered in four doses.
- Vaccine efficacy is influenced by prevalent serotypes causing invasive disease and is less effective in patients with specific underlying health conditions (asplenia, sickle cell disease, etc.).
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the characteristics and classification of Streptococcus and Enterococcus. This quiz covers their morphology, growth requirements, hemolysis patterns, and significance in infections. Test your knowledge on these important bacteria commonly studied in microbiology.
