Streptococcus, Enterococcus and Similar Organisms

Sodium desoxycholate

10% solution that induces autolytic process of S. pneumoniae, interacts with organisms amidase present in cells. (bile solubility)

Serologic Response in Rheumatic fever

ASO, anti-hylauronidase, and/or anti-DNase positive

M protein

Affect the pathogenesis of rheumatic fever and glomerulonephritis, not present in any other Lancefield group (B), highly variable with greater than 100 serotypes.

Serologic Response in Glomerulonephritis

Anti-hylauronidase, and/or anti-DNase positive (No ASO, oxygen labile, skin is exposed to air, most common following skin infections)

Lancefield Group

Beta-hemolytic streptococci are classified based on cell wall carbohydrates. Some are opportunistic pathogens where as others are clearly clinically significant.

Group D streptococcus

Bile esculin positive, will not grow in NaCl (enterococci are salt tolerant)

Bile Solubility Test

Bile or a solution of a bile salt (sodium deoxycholate) rapidly lyses pneumococcal colonies. Lysis depends on the presence of an intracellular autolytic enzyme, amidase.

CAMP Test

Christie, Atkins, Munch-Peterson test used to differentiate Group B, S. agalactiae from other streptococal species. Listeria monocytogenes also produces a positive CAMP reaction. The organisms produce a CAMP factor hemolytic protein that acts synergistically with the beta-lysin of S. aureus producing an enhanced arrowhead of hemolysis.

S. pneumoniae

Colonizer of the nasopharynx, person to person or contaminated respiratory secretions for transmission. Causes pneumoniae when accumulation occurs in the lower respiratory tract. Alpha hemolytic

SXT Agar

Common selective media for isolating Group A streptococci from throat swabs. 5% sheep blood supplemented with trimethoprim-sulfamethoxazole to suppress the growth of normal flora.

Phosphorylcholine

Contained in the cell wall of S. pneumoniae, binds the receptors of the platelet-activating factor in endothelial cells, WBC's, platelets and tissue cells of lungs and meninges, facilitating entry of the organism and spread.

BHI 6.5% Salt Tolerance

Differentiates Enterococcus species from viridans streptococcus. Enterococcus is positive for growth, viridans streptococcus are negative for growth.

Glomerulonephritis

Edema, hypertension, hematuria, and proteinuria, can follow either respiratory or cutaneous infections but more often the later. Results from antigen-antibody complexes deposited in the kidneys.

Incubation Conditions

Enriched CO2, 5-10% 35-37 degrees Celsius.

Alpha hemolytic, Bile esculin positive, Salt Tolerant, PYR Positive, mannitol positive

Enterococcus

Limitation of Bile Solubility

Enzyme activity may be reduced in old cultures, therefore negative results with colonies resembling S. pneumoniae should be confirmed with alternate methods.

Optochin (Taxo P)

Ethylhyrocupriene hydrochloride S. pneumoniae susceptible (positive) and S. pyogenes resistant (negative) Optochin interferes with the ATPase production of ATP in microorganisms. Zone of 14-16 mm is considered susceptible and presumptive identification of S. pneumoniae. May be considered confirmatory in the teaching lab when instructed to do a manual identification only.

CAMP Factor

Extracellular protein produced by S. agalactiae, acts synergistically with beta-lysin positive S. aureus producing enhanced hemolysis.

Rheumatic fever

Fever, endocarditis (cross reactivity with M protein in heart muscle), subcutaneous nodules and poly arthritis, usually follows respiratory infection.

Gram stain morphology

Gram positive cocci in chains or pairs. The cells only divide along the single axis. Typically round or oval, occassionally they will form elongated cells, especially following antibiotic treatment of a patient.

Hippurate hydrolysis

Group B, S. agalactiae and L. monocytogenes is hippuricase positive, hippuric acid is hydrolyzed (positive reaction is purple) visualized with the addition of ninhydrin

40% Bile

Inhibits most gram positive cocci except enterococci and group D streptococci

40% Bile

Inhibits most gram positive cocci except enterococci and group D streptococci.

Bacitracin sensitive

Micrococcus and Streptococcus pyogenes

Streptococcus dysgalactiae subsp. equisimilis

Mimics S. pyogenes and has been associated with the development of rheumatic fever

Streptococcus dysgalactiae subsp. equisimilis

Mimics S. pyogenes and has been associated with the development of rheumatic fever.

Enterococcus spp.

Normal microbiota of humans, animals and birds. Both E. facium and E. faecalis are normal flora of the human gastrointestinal tract and female genitourinary tract. Endogenous, person to person transmission or contaminated medical equipment. Gamma, alpha or rarely beta-hemolytic.

S. agalactiae

Normal microbiota of the female genital tract and the lower gastrointestinal tract; endogenous, person to person transmission or unwashed hands and direct contact. Narrow zone beta hemolysis

Viridans streptococci

Normal microbiota of the oral cavity, gastrointestinal tract, female genital tract. Endogenous gain access to sterile sites often from dental manipulations. Alpha hemolytic but may be beta-hemolytic

S. pyogenes

Not considered normal microbiota, nasal carriage, pharangeal, almost always clinically significant, person to person or aersolized droplet transmission. Beta-hemolytic

Ethylhydrocuperine hydrochloride

Optochin

Groups C, F, G

Other beta-hemolytic streptococci that are normal microbiota of the skin, nasopharynx, gastrointestinal and genital tract. Endogenous, person to person transmission

Bile Esculin

Presumptive identification of Enterococcus spp. Gram positive bacteria other than some streptococci and enterococci are inhibited by the bile salts in this media. The biochemical is the hydrolysis of esculin to esculetin that reacts with Fe3+ to form a black precipitate.

Ferric ammonium citrate

Produces black/brown precipitate when esculin is hydrolyzed

Ferric ammonium citrate

Produces black/brown precipitate when esculin is hydrolyzed.

Hippurate Hydrolysis

Production of hippuricase hydrolyzes hippuric acid producing glycine and benzoic acid. The glycine is then deaminated by the addition of ninhydrin and then the ninhydrin is oxidized producing a purple product. Differentiates S. agalactiae (positive) from S. pyogenes (negative)

Beta hemolytic, PYR negative, VP negative Resistant to bacitracin and CAMP positive

S. agalactiae

Neonatal Infection

S. agalactiae infection occurs during or before birthing process. May cause septicemia, pneumonia and meningitis in newborns.

Alpha hemolytic, mannitol positive, PYR negative, urease negative

S. mutans (Viridans streptococci)

Alpha hemolytic, bile solubility positive, optochin sensitive

S. pneumoniae

D Zone

S. pneumoniae or other beta hemolytic streptococci that are resistant to erythromycin and either susceptible or intermediately resistant to clindamycin should be examined for inducible clindamycin resistance. 5% Sheep blood agar is required for the media.

PYR positive

S. pyogenes, (y)Enterococcus spp., and S. (r)lugdunensis.

PYR positive

S.lugdunensis, Enterococcus spp., S. pyogenes

Beta hemolytic, PYR positive Bacitracin sensitive, VP negative

S.pyogenes (Group A)

Streptococcal pyrogenic exotoxins

SPES produce scarlet fever, maifested in streptococcal pharyngitis, rash on the face and upper trunk. Erythorgenic toxins produced by lysogenic strains (Bacteriophage containing)

Enterococcosel agar

Selective and differential medium based on the esculin hydrolysis and selective by the incorporation of bile salts to inhibit the growth of other gram positive organisms, with the exception of Group D streptococci.

Catalase negative Gram positive cocci

Streptococcus and Enterococcus species

Catalase negative gram positive cocci

Streptococcus and Enterococcus species

Other Gram positive cocci test methods

These were all described and included in the staphylococci chapter quizlet.

LIM Broth

Todd Hewitt broth with CNA, selective enrichment for Group B, S. agalactiae

LIM Broth

Todd-Hewitt Broth with Colistin and Nalidixic Acid inhibits the growth of gram negative bacteria and normal vaginal flora. Selectively used to isolate group B streptococci from clinical specimens.

6.5% NaCl

Used to determine salt tolerance, Enterococci are able to grow, most other streptococci and Group D enterococci (previously streptococci) are unable to grow.

Pneumolysin

Virulence factor produced by S. pneumoniae, that activates classic complement pathway. Suppresses oxidative burst in phagocytes, provding evasion of the immune system.

CAMP Factor

extracellular protein produced by S. agalactiae, acts synergistically with beta-lysin positive S. aureus producing enhanced hemolysis (CAMP fire)

Streptolysin O

oxygen labile, immunogenic, capable of lysing same cell types of Streptolysin O. S. pyogenes. Also inhibited by cholesterol in skin lipids, which also accounts for the reason skin infections do not result in the production of antistreptolysin O antibodies

Streptolysin S

oxygen stable, non-immunogenic hemolysin capable of lysing RBC's, WBC's and platelets in room air. S. pyogenes

Streptococcus pseudopneumoniae

treptococcus pseudopneumoniae is a recently described member of the Streptococcus mitis/oralis group of viridans Streptococci that shares some characteristics with S. pneumoniae1. Key features of S. pseudopneumoniae are the absence of pneumococcal capsule, insolubility in bile, resistance or indeterminate susceptibility to optochin when incubated in 5 per cent CO2 but susceptibility to optochin when incubated in ambient air, positive reactions in DNA probe hybridization and antigen detection

Group D streptococcus

►+ Bile esculin positive ►- Will not grow in NaCl (enterococci are salt tolerant).

Bile solubility (sodium deoxycholate)

►10% solution that induces autolytic process of S. pneumoniae. ►Interacts with organisms amidase present in cells.

Serologic Response in Rheumatic fever

►ASO. ►Anti-hyaluronidase and/or anti-DNase positive.

M protein

►Affect the pathogenesis of rheumatic fever and glomerulonephritis, not present in any other Lancefield group (B). ►Highly variable with greater than 100 serotypes.

Streptococcus mutans (Viridans streptococci)

►Alpha hemolytic. ►Gram POSITIVE cocci in chains. ►Lancefield non-groupable. ►+ Mannitol POSITIVE. ►- PYR negative. ►- Urease negative.

Serologic Response in Glomerulonephritis

►Anti-hyaluronidase, and/or anti-DNase positive. ►Most common following skin infections. ►NO ASO, oxygen labile, skin is exposed to air.

Lancefield Group

►Beta-hemolytic streptococci are classified based on cell wall carbohydrates. ►Some are opportunistic pathogens whereas others are clearly clinically significant.

Streptococcus pneumoniae

►Colonizer of the nasopharynx. ►Person to person or contaminated respiratory secretions for transmission. ►Causes pneumoniae when accumulation occurs in the lower respiratory tract; rust colored sputum. ►Alpha hemolytic. ►Gram POSITIVE lancet-shaped diplococci. ►+ Bile solubility POSITIVE. ►S Optochin sensitive.

SXT Agar

►Common selective media for isolating Group A streptococci from throat swabs. ►5% sheep blood supplemented with trimethoprim-sulfamethoxazole to suppress the growth of normal flora.

Phosphorylcholine

►Contained in the cell wall of S. pneumoniae. ►Binds the receptors of the platelet-activating factor in endothelial cells, WBCs, platelets and tissue cells of lungs and meninges, facilitating entry of the organism and spread.

Acute (Post-streptococcal) Glomerulonephritis

►Edema, hypertension, hematuria, and proteinuria. ►Can follow either respiratory or cutaneous infections but more often the later. ►Results from antigen-antibody complexes deposited in the kidneys.

Streptococcus Incubation Conditions

►Enriched CO2: 5-10%. ►35-37 degrees Celsius.

Rheumatic fever

►Fever, endocarditis (cross reactivity with M protein in heart muscle), subcutaneous nodules and polyarthritis. ►Usually follows respiratory infection.

Streptococcus Gram stain morphology

►Gram positive cocci in chains or pairs. ►Cells only divide along the single axis. ►Typically round or oval, occasionally they will form elongated cells, especially following antibiotic treatment of a patient.

Hippurate hydrolysis positive

►Group B, S. agalactiae, and L. monocytogenes is hippuricase positive. ►Hippuric acid is hydrolyzed (positive reaction is purple) visualized with the addition of ninhydrin.

Enterococcus spp.

►Normal microbiota of humans, animals and birds. ►Both E. faecium and E. faecalis are normal flora of the human gastrointestinal tract and female genitourinary tract. ►Endogenous, person to person transmission or contaminated medical equipment. ►Gamma, alpha or rarely beta-hemolytic. ►+ Bile esculin POSITIVE ►Growth 6.5% NaCl ►+ PYR Positive. ►+ Mannitol POSITIVE.

Streptococcus agalactiae

►Normal microbiota of the female genital tract and the lower gastrointestinal tract. ►Endogenous, person to person transmission or unwashed hands and direct contact. ►Narrow zone beta hemolysis. ►- PYR negative. ►- VP negative ►R Bacitracin Resistant ►+ CAMP positive

Viridans streptococci

►Normal microbiota of the oral cavity, gastrointestinal tract, female genital tract. ►Endogenous gain access to sterile sites often from dental manipulations. ►Alpha hemolytic but may be beta-hemolytic.

Streptococcus pyogenes (Group A Strep)

►Not considered normal microbiota. ►Nasal carriage, pharyngeal, almost always clinically significant. ►Person to person or aerosolized droplet transmission. ►Beta-hemolytic. ►- Catalase negative ►+ PYR positive ►S BAcitracin Susceptible ►- VP negative

Groups C, F, G

►Other beta-hemolytic streptococci that are normal microbiota of the skin, nasopharynx, gastrointestinal and genital tract. ►Endogenous, person to person transmission.

Streptolysin O

►Oxygen labile, immunogenic hemolysin, capable of lysing RBCs, WBCs and platelets in anaerobic environments. ►S. pyogenes. ►Also inhibited by cholesterol in skin lipids, which also accounts for the reason skin infections do not result in the production of antibodies to this hemolysin.

Streptolysin S

►Oxygen stable, non-immunogenic hemolysin capable of lysing RBCs, WBCs and platelets in room air. ►S. pyogenes.

Streptococcal Pyrogenic Exotoxins (SPEs)

►Produce scarlet fever. ►Manifested in streptococcal pharyngitis, rash on the face and upper trunk. ►Erythrogenic toxins produced by lysogenic, bacteriophage containing, strains.

Streptococcus pseudopneumoniae

►Recently described member of the Streptococcus mitis/oralis group of viridans Streptococci that shares some characteristics with S. pneumoniae. ►Key features are: ○Absence of pneumococcal capsule. ○Insolubility in bile. ○Resistance or indeterminate susceptibility to optochin when incubated in 5% CO2 but susceptibility to optochin when incubated in ambient air. ►Positive reactions in DNA probe hybridization and antigen detection.

Group B Strep Neonatal Infection

►S. agalactiae infection occurs during or before birthing process. ►May cause septicemia, pneumonia and meningitis in newborns.

D-zone test

►S. pneumoniae or other beta hemolytic streptococci that are resistant to erythromycin and either susceptible or intermediately resistant to clindamycin. ►Should be examined for inducible clindamycin resistance. ►5% Sheep blood agar is required for the media.

Enterococcosel agar

►Selective and differential medium based on the esculin hydrolysis. ►Selective by the incorporation of bile salts to inhibit the growth of other gram positive organisms, with the exception of Group D streptococci.

LIM Broth

►Todd-Hewitt Broth with Colistin and Nalidixic Acid. ►Inhibits the growth of gram negative bacteria and normal vaginal flora. ►Selective enrichment used to isolate Group B streptococci from clinical specimens.

6.5% NaCl

►Used to determine salt tolerance. ►Enterococci are able to grow. ►Most other streptococci and Group D enterococci (previously streptococci) are unable to grow.

Pneumolysin

►Virulence factor produced by S. pneumoniae, that activates classical complement pathway. ►Suppresses oxidative burst in phagocytes, providing evasion of the immune system.