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Streptococcus &
Enterococcus
Gram-positive cocci (spherical to ovoid cells) - often arranged in chains and/or pairs - facultative - catalase negative TERM 2
Species identification of streptococci
DEFINITION 2 hemolytic reactionsbiochemical testsserological reactions TERM 3
Hemolytic reactions caused by specific
bacterial enzymes
DEFINITION 3 hemolysis - green discoloration (partial hemolysis) of blood cells surrounding colony (beta) hemolysis - clearing (complete lysis) of blood cells surrounding colonies (gamma) nonhemolytic (no change) of blood cells surrounding colonies TERM 4
Physiological Identification
DEFINITION 4 antibiotic sensitivity / resistance -hemolytic --> optochin - hemolytic --> bacitracin other biochemical tests TERM 5
Serological Identification (1) Lancefield
grouping
DEFINITION 5 presence of antigenically unique "C" carbohydrates in the cell wall Group A Streptococcus pyogenesGroup B Streptococcus agalactiaeGroup D Enterococcus faecalis Enterococcus faecium Streptococcus bovis
Serological Identification (2) typing
serological identification within a group or species >80 types of Group A (S. pyogenes) antigenically unique M protein(s) associated with cell wall / fimbria > 85 types of S. pneumonia antigenically unique capsular polysaccharide TERM 7
Streptococci &
Enterococci
DEFINITION 7 -hemolytic (usually)Streptococcus pneumoniae viridans group (> 12 species) Streptococcus sanguinis Streptococcus mutans non-hemolytic (usually) Enterococcus faecalis Enterococcus faecium TERM 8
-hemolytic streptococci - S. pneumoniae
DEFINITION 8 Epidemiology normal flora / colonizes the oropharynx frequency : children 40-70% & adults 5-20%person-to-person transmission by respiratory droplet or direct contactmost healthy individuals are resistant to diseasePredisposing factors for disease
- previous pharyngitis or common cold - elderly - influenza - alcoholism - chronic cardiac/respiratory disease TERM 9
-hemolytic streptococci - Virulence factors
DEFINITION 9 polysaccharide capsule (inhibits phagocytosis in the absence of specific antibody) >80 serological types of capsular polysaccharide produces disease by growth in tissue and subsequent inflammation TERM 10
-hemolytic streptococci - S. pneumoniae
DEFINITION 10 most common cause (60-80%) of community-acquired pneumonia (CAP)sudden onset, difficulty breathing, fatigue, cough,violent shaking chill, high fever 102-106E Flobar pneumonia - "rusty" or bloody sputum
Septicemia
persistence of bacteria &/or their toxins in the blood pathologic stateSince there has been so much misuse and confusion regarding these terms it is now recommended to use the term sepsis, rather than septicemia TERM 17
Prophylactic Treatment to Reduce Risk of
Endocarditis
DEFINITION 17 High risk groups previous endocarditis prosthetic heart valves unrepaired cyanotic congenital heart disease repaired cyanotic congenital heart disease (to 6 months post surgery) Procedures dental extractions, periodontal treatment, oral surgeries invassive respiratory tract procedures surgery of infected soft tissues gastrointestinal and/or gentourinary tract procedures tatooing & body piercingTreatment regimens vary, ampicillin, amoxicillin, cefazolin, others TERM 18
nonhemolytic streptococci (sometimes -
hemolytic) - Enterococcus
DEFINITION 18 belong to Lancefield Group D normal microbiota of i ntestinal tractEnterococcus faecalis & Enterococcus faecium cause ~ 90% of clinical enterococcal infections TERM 19
ENTEROCOCCI - Clinical presentations
DEFINITION 19 urinary tract infectionswound infections / intestinal abscessesendocarditis** meningitis (uncommon) *** most frequently nosocomial infections,** top 3 causes staphylococci, E.coli, enterococci TERM 20
ENTEROCOCCI - Treatment
DEFINITION 20 resistant to many antimicrobialsRecommended Treatment ampicillin (or vancomycin) w/ aminoglycoside (gentamycin) Emerging antibiotic resistance Enterococcus faecium / vancomycin resistance
-hemolytic streptococci - Group A - Group B
bacitracin disc test | sensitive ------------------ -----------------
- resistant | | S. pyogenes hippurate test Group A | positive -------- -------------negative | | S. agalactiae others non-A,,non-B Group B TERM 22
Streptococcus pyogenes / Group A
DEFINITION 22 Epidemiology ~ normal flora 5-20% of healthy people usually throat / less common skin Transmission person to person respiratory droplet direct contact
