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Flashcards in Streptococci Deck (27)
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Name 3 species of the mutans streptococcus group

1. S. mutans 2. S. sobrinus 3. S. cricetus


Mode of action of mutans streptococcus

They bind to and colonise the tooth surface by producing extracellular polysaccharides (sucrose)


Name 3 virulence factors of streptococcus pyogenes required for adherence

1. M protein 2. Fibronectin binding protein (Protein F) 3. Lipoteichoic acid


Major causes of infective endocarditis

1. S. sanguinis (32%) 2. S. oralis (30%) 3. S. gordonii (13%)


Name some members of the viridans group streptococci Describe their appearance on a CBA.

Streptococcus mutans Streptococcus salivarius Streptococcus sanguinis Streptococcus mitis Green colonies Alpha-haemolytic


What does pyrogenic exotoxins cause?

- Scarlet fever - Toxic shock like syndrome (TSLS)


Which bacteria is the leading cause of dental caries?

Streptococcus mutans


What does GAS bacteria cause? Name one bacteria

Streptococcus pyogenes "Strep" throat Scarlet fever Rheumatic fever Post-streptococcal glomerulonephritis (PSGN) Necrotising fasciitis


Antibiotic treatment for GAS?

1. Penicillin (10 day course) 2. Amoxicillin (but narrow spectrum acceptable for children) 3. Erythromycin (for patients sensitive to penicillin) 4. CoAmoxy-Clav Clindamycin (for repeated infections)


Where would one expect to find Streptococcus salivarius?

Saliva and tongue; (keratinised surfaces of mouth) Upper respiratory tract; GI tract


Name 2 properties of mutans streptococcus

1. Acidogenic - produce acid at a high rate from sugar 2. Aciduric - tolerate high concentrations of acid


Where would one expect to find Streptococcus mutans?

On tooth surfaces/fissures


Name the group of bacteria that appears to have a "greening" effect on CHOC

Viridans group of streptococcus


What test can be carried out to differentiate streptococcus from staphylococcus?

1. Gram stain --> Streptococcus appear as chains; Staphylococcus appear as grape-like clusters 2. Catalase test --> Streptococcus - catalase negative Staphylococcus - catalase positive


What can streptococcus anginosus lead to?

Nasty infections: - oral abscesses & brain, liver - bacteraemia & endocarditis - appendicitis & peritontitis


Name the bacteria that have 'beta' haemolytic activity on CBA

Streptococcus Pyogenes; Streptococcus Anginosus


Name a bacteria sensitive to bacitracin

Streptococcus Pyogenes


What does M protein serve as?

Major virulence factor for the group A streptococcus. It inhibits the activation of complement and protects the organism from phagocytosis. However, plasma (B) cells generate antibodies against the M protein, which bind to the M protein (opsonization), aiding in the destruction of the organism by macrophages and neutrophils.


Name a bacteria sensitive to optochin

Streptococcus Pneumonia


Viral pharyngitis VS "Strep Throat"?

Absence of fever and presence of cough in viral pharyngitis


Name 5 members of the oralis group of streptococci

1. Streptococcus oralis 2. Streptococcus sanguinis 3. Streptococcus gordonii 4. Streptococcus mitis 5. Streptococcus crista


Where would one expect to find Streptococcus anguinosis?

On dental plaque and abscesses


Name the bacteria with 'alpha' haemolytic activity on CBA

Viridans group of streptococcus; Streptococcus pneumonia


Where would one expect to find Streptococcus oralis?

On tooth, forming biofilms


Name 3 main types of infections caused by the viridans group of streptococcus

1. Dental infections - caries 2. Endocarditis 3. Abscesses


Function of hyaluronic acid capsule in S. pyogenes

Serve as a virulence factor - 1. Evasion of host defences: function as an immunological disguise as it produces hyaluronic acid which is similar to human produced ones, hence reducing phagocytosis 2. Functions in tissue penetration/spread


Type of vaccine used against Strep. Pneumonia

Inactivated (Killed) vaccine