StreptocoStreptococcicci

IntroductionIntroduction

Pyogenic pathogens - nonmotile, catalase negative, Gram positive cocci in chains

Freshly isolated Streptococcus

3

Catalase test

6

ClassificationClassification

Hemolysis on blood agar plates

Cell wall group-specific Cell wall group-specific substance substance

HemolysisHemolysis

β hemolytic

α hemolytic

γ hemolytic (no hemolysis)

Lancefield groups Lancefield groups A-H and K-UA-H and K-U

S pyogenes( group A)S pyogenes( group A)S agalactiae( group B)S agalactiae( group B)Enterococci( group D)Enterococci( group D)S pneumoniaeS pneumoniaeViridans streptococciViridans streptococcipeptostreptococcuspeptostreptococcus

BACKGROUND

Group A beta-hemolytic streptococci (Streptococcus pyogenes) is one of the most commonly encountered pathogens in humans.

Streptococcus Streptococcus pyogenespyogenes

SpecimensSpecimens

SmearsSmears

CultureCulture

Biochemical testBiochemical test

Streptococcus Streptococcus pyogenespyogenes

Bacitracin testBacitracin test

Streptococcal tests

17

PYR testPYR test L-pyrrolidonyl-L-pyrrolidonyl-

ß-ß-naphthylamidenaphthylamide

dimethylaminodimethylaminocinnamaldehycinnamaldehydede

Hemolysis patterns on blood agar

19

Streptococcus agalactiaeGroup B

Chronic bovine mastitis promoted by milking machines slowly progressing inflammation, fibrosis fibrin plugs in smaller milk ducts: loss of milk-

producing capacity (agalactia) Neonatal meningitis in humans

early onset septicemia (≈ 15% of all neonatal septicemias)

late onset: purulent meningitis (average 4.8 weeks after birth)

5 - 10 % of pregnant women are reproductive tract carriers

Most infection in newbornsMost infection in newborns Asymptomatic colonization of the upper Asymptomatic colonization of the upper

respiratory and genitourinary tractrespiratory and genitourinary tract

Streptococcus Streptococcus agalactiaeagalactiae

Asymptomatic colonization of the Asymptomatic colonization of the upper respiratory and genitourinary upper respiratory and genitourinary tracttract

Most infection in newbornsMost infection in newborns

DiagnosisDiagnosis Hydrolyze sodium Hydrolyze sodium

hippuratehippurate

CAMP testCAMP test

Hydrolyze sodium Hydrolyze sodium hippuratehippurate

CAMP testCAMP test

-hemolytic streptococci

25

Streptococcus Streptococcus pneumoniaepneumoniae

Gram positive Gram positive diplococci( lancet-diplococci( lancet-shaped)shaped)

Possessing a capsulePossessing a capsule

Normal inhabitants of Normal inhabitants of the upper respiratory the upper respiratory tracttract

Diagnosing Streptococcus pneumoniae

28

Optochin testOptochin test

Bile solubility testBile solubility test

Viridans Viridans streptococcistreptococci

Found in the upper respiratory tract

Endocarditis 30-40% of cases due

to viridans viridans streptococci

EnterococciEnterococci Part of normal enteric floraPart of normal enteric flora Important species Important species

1.1. Enterococcus faecalisEnterococcus faecalis

2.2. Enterococcus faeciumEnterococcus faecium Grow in the 10˚ C to 45˚ CGrow in the 10˚ C to 45˚ C Typically non hemolyticTypically non hemolytic Grow in the presence of 6.5 % Grow in the presence of 6.5 %

NaClNaCl Hydrolyze esculinHydrolyze esculin