Microbiology - 0418, 0419 - Staphylococcus and Streptococcus

• Streptococcus oralis
• Streptococcus mitis
• Streptococcus salivarius
• Actinomyces spp.
• Veillonella spp.
• Neisseria spp.
• All G(+), no spores

• transmitted by contact -> Colonization -> Acid production -> Demineralization -> Cavitation
• Adherence to tooth surface
• Production of extracellular polysaccharide (protection)
• Acidogenesis and Aciduricity (competency)
• Significant in causing caries

• Binding to salivary pellicle
• Autoaggregation
• Coaggregation

• Glucosyltransferase
• Made by Streptococcus, Lactococcus and Lactobacillus
• Transform sucrose into glucans and fructose (converted to lactic acid)

GBP, between the cell and glucans, forming a robust biofilm

• S. sanguis
• Lactobacilli

• Mechanical washing - flow rate, Xerostomia, circadian rhythm
• Buffering - sugary diet; Stephan cu
• Antibacterial activity
• Aggregation of bacteria
• Remineralization of enamel

• Interfere with transmission
• Eliminate S. mutans from the oral cavity
• Increase acid resistance of enamel
• Control carbohydrate composition of diet

• Vaccines
• Enzymes (mutanase and dextranase)
• Strain replacement therapy

• Mechanical removal of plaque
• Biocides (chlorhexidine, SDS, CPC, antibiotics, bacteriocins)

• Fluoride
• Pit and fissure sealants

• Xylitol
• Aspartame

• clusters
• chains

• G + cocci
• 0.5-1.5 um
• Nonmotile, no flagella, etc
• Facultative anaerobic
• Can grow in high salt (10% NaCl)
• 18-40 C
• Part of the normal flora (nasal, skin) - S. aureus and S. epidermidis, do not cause disease until they get into blood

• golden
• white

• device infections
• bacteremia

• many more infections, including wound and burn infections
• high resistance

• Catalase catalyze H2O2 to H2O and O2
• Staph has catalase, after adding H2O2, foamy.
• Strep doesn't have catalase, no much effect.

•  S. aureus has 11 capsule serotypes.
•  Serotype 5 and 7 are associated with infection.

Mediates adhesion to epithelial cells and biofilm formation.

• Half of the cell wall weight is peptidoglycan.
• In MRSA mecA codes for PBP2 that does not bind penicillin.

Microbial surface components recognizing adhesive matrix molecules

structure that goes through G+ bacteria that allows them to stick to the organism as well

• Coats surface of S. aureus
• very high affinity for the Fc receptor of IgG (IgG tags the cell in a wrong way)
• prevent opsonization and phagocytosis.
• inhibit antibody mediated clearance.

• Cell free coagulase.
• Converts fibrinogen to insoluble fibrin, which causes
• clumping and aggregation.
• Collagenase - can cause the formation of a protective fibrin layer around the cell.
• S. aureus is coagulase positive; S. epidermidis is coagulase negative.

Fibrinolysin or Staphylokinase, Hyaluronidase, Lipase, Deoxyribonuclease, Fatty acid modifying enzyme (FAME)

• α-toxin (α-hemolysin) - Forms pores in cell membranes and causes tissue damage.
• β-toxin - Hydrolysis of membranes.
• δ-toxin - Nonspecific membrane toxin.
• γ-toxin and Panton-Valentine (PV) leukocidin- Lyse neutrophils and macrophages.

• Exfoliating toxin A and B -  Serine protease, Staphylococcal scalded skin syndrome (SSSS)
• Enterotoxins (A-E, G-I) - food poisoning, resistant to high temp, and gastric enzymes.
• TSST-1 - toxic shock syndrome toxin - 1, Superantigens, bind to macrophages and interact with T-Cells and releases cytokines- shock and high fever and organ failure.

• •  Hospital acquired.
• •  Typically found in immunodeficient patients.

• •  Community acquired.
• •  Typically found in healthy individuals.

• most common bacteria on skin.
• Found on everyone.
• Opportunistic pathogen.
• Coagulase negative Staphylococci
• medical devices colonizing

• Attachment to biomaterials. Biofilm formation.
• Protection from antimicrobial killing and phagocytosis.

• Group A
• Puerperal fever (childbed fever)
• Pharyngitis (Strep throat)
• Scarlet fever
• Rheumatic fever
• Bacteremia
• Cellulitis (skin infection)
• Acute necrotizing fasciitis (flesh-eating bacteria)
• Toxic shock syndrome

• Avoiding opsonization and phagocytosis
• Surface attachment.
• Cell invasion.
• Toxins.
• Enzymes.

hyaluronic acid capsule weak immunogen

• binds to host proteins to avoid detection
• Protects against phagocytosis
• Mediates attachment to keratinocytes
• Autoaggregation

• S. pyogenes exotoxin (Spe)- superantigen, releases cytokine release, cause toxic shock-like syndrome (TSLS), rash and necrotizing fasciitis (flesh-eating).
• Streptolysin S - cell-bound hemolysin, which is responsible for lyses of blood cell.
• Streptolysin O - also an hemolysin.

• Streptokinase A and B - cleave plasminogen and lyse blood clots.
• DNases A-D- reduce DNA in pus, which can aid in bacteria spread.

B

• Infection in newborn -  Group B streptococci colonize the vaginal and gastrointestinal tracts in 15%-45% of healthy women; protected by ointment.
• underlying abnormalities
• • Bacteremia
• • Pneumonia
• • Wound infection
• • Urinary tract infection
• • Skin infection

• polysaccharide capsule reduces phagocytosis
• Toxin- β-hemolysin

• G +
• Dilococci- in pairs
• Encapsulated - smooth colony vs rough colony
• grow only on enriched media with blood

• 90 capsule serotypes
• Surface protein adhesions.
• mediate cytokine production, inflammation - fever, and tissue damage.
• Phosphocholine on the cell well can mediate cell and tissue invasion, allowing protection from opsonization and phagocytosis.
• Choline-binding Proteins