Streptococcus and Enterococcus Flashcards
What is the oxygen requirement for Streptococcus spp.?
Facultatively anaerobic
What is required for the growth of Streptococcus spp.?
Blood or enriched medium
What is the Lancefield Classification used for?
Classification of Streptococci by group specific antigen (C carbohydrate)
Which species of strep is classified under the group A Lancefield?
Streptococcus agalactiae
Which species of strep is classified under the group B Lancefield?
Streptococcus pyogenes
What is one method for non-cultural identification of Streptococcus?
Slide Agglutination Test
What is the most common clinical presentation of Group A strep infection?
Bacterial Pharyngitis (strep throat)
What are two complications associated with Streptococcus pyogenes?
- Rheumatic fever
- Acute Glomerulonephritis (AGN)
What disease is characterized by a diffuse red rash that begins on the upper chest?
Scarlet Fever
What type of test is used for throat swab culture from a child with strep throat?
Blood agar plate
What Gram staining result is typical for Streptococcus pyogenes?
Many Gram-positive cocci in chains or pairs
What is one virulence factor of Streptococcus agalactiae?
Capsule which can prevent phagocytosis
What is a common clinical infection caused by Streptococcus agalactiae in newborns?
Meningitis
What should be removed before specimen collection from the cervix/vagina?
Mucus
What type of infections can Group D Streptococci cause?
- Urinary tract infections
- Endocarditis
- Wound infections
- Abscesses
What is a characteristic of Enterococcus spp. in terms of their location?
Found in the intestinal tract
What type of hemolysis can Enterococcus spp. exhibit?
Alpha-, beta-, or non-hemolytic
What is the main virulence factor associated with Streptococcus pneumoniae?
Capsule
What disease is Streptococcus pneumoniae a common cause of?
Pneumonia
Fill in the blank: Streptococcus pyogenes is known as Group ___ streptococci.
B
True or False: Streptococcus agalactiae can cause pneumonia in newborns.
True
What test is used for presumptive identification of Streptococcus pyogenes?
Bacitracin test
What is the appearance of Streptococcus pyogenes colonies on sheep blood agar?
Small, smooth, translucent with a well-defined zone of beta hemolysis
What are common clinical infections caused by S. pneumoniae?
- Pneumonia
- Otitis Media
- Sinusitis
- Bacterial Meningitis
- Endocarditis
- Peritonitis
- Bacteremia
S. pneumoniae is a common pathogen and can be part of the normal respiratory flora.
What is the procedure for sputum specimen collection?
Rinse mouth, cough deeply into a sterile container, refrigerate if delayed
Specimens should be collected in sterile, screw-cap containers.
What is the microscopic morphology of S. pneumoniae?
Gram-positive lanceolate shaped diplococci, can appear singly or in chains
This morphology is key for identification in laboratory settings.
Describe the colonial morphology of S. pneumoniae.
Glistening wet, mucoid, dome shaped and round colonies, displaying alpha-hemolysis
Autocatalysis can result in a depression in the colonies.
What biochemical tests are used to identify S. pneumoniae?
- Catalase
- Bile Esculin
- Optochin Susceptibility
- Bile Solubility
These tests differentiate S. pneumoniae from viridans streptococci.
What characterizes viridans streptococci?
Gram-positive cocci, often alpha-hemolytic, found in the mouth
They are opportunistic pathogens, causing disease in immunocompromised hosts.
What diseases are commonly associated with viridans streptococci?
- Subacute bacterial endocarditis
- Meningitis
- Dental caries
- Osteomyelitis
- Empyema
Viridans streptococci are oropharyngeal commensals that can cause these infections.
What is the colonial morphology of viridans streptococci?
Small colonies, grey, dry, translucent, alpha-hemolytic or non-hemolytic
This appearance aids in their identification in the laboratory.
What is the clinical significance of the S. anginosus group?
Can cause bacteremia, abscess formation, endocarditis, respiratory infections, osteomyelitis, septic arthritis, cellulitis
Group C and G are normal flora, while group F is found in the oral cavity.
What biochemical tests are used for the S. anginosus group?
- PYR -
- Hippurate -
- CAMP -
- VP +
- BGUR -
These tests help differentiate between species in the group and assess their biochemical characteristics.
True or False: S. mutans is a beta-hemolytic streptococcus.
False
S. mutans is an alpha-hemolytic viridans streptococcus.
Fill in the blank: S. sanguis is known for producing a _______ color on blood agar.
green
This green color is due to its alpha-hemolytic properties.
