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Streptococcus and Enterococcus: Definition, Identification, and Clinical Manifestations, Quizzes of Microbiology

Definitions, identification methods, and clinical manifestations of streptococcus and enterococcus, two common groups of gram-positive bacteria. Topics covered include hemolytic reactions, serological identification, virulence factors, epidemiology, and treatment. These bacteria are known to cause various infections, such as pneumonia, meningitis, and bacteremia.

Typology: Quizzes

2012/2013

Uploaded on 07/25/2013

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TERM 1
Streptococcus &
Enterococcus
DEFINITION 1
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 wallGroup A Streptococcus pyogenesGroup B
Streptococcus agalactiaeGroup D Enterococcus faecalis
Enterococcus faecium Streptococcus bovis
pf3
pf4
pf5

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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