Streptococcus Flashcards by James Sandoval

Appears as lancet – shape or diplococci)

Streptococcus pneumoniae

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Streptococcus O2 and CO2 requirement

Facultative anaerobe

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NOTE‼️: Genus streptococcus are commonly found as part of normal flora; encountered in clinical specimens as contaminants or as components of mixed cultures with minimal or unknown clinical significance.

pasar bacte qt ehehe

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BROWN and SMITH: ALPHA hemolytic (partial hemolysis)

*Viridans streptococci

*Streptococcus pneumoniae

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BROWN and SMITH: BETA hemolytic (complete hemolysis)

Streptococcus pyogenes (Group A)

Streptococcus agalactiae
(Group B)

Streptococcus equisimilis, zoopedemicus, equi
(Group C)

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BROWN and SMITH: GAMMA hemolytic (Non-hemolytic)

Enterococcus faecalis

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LANCEFIELD CLASSIFICATION is based on what carbohydrate?

Based on the C – carbohydrate antigen found in the cell wall

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DO NOT have carbohydrate cell wall antigen

Streptococcus pneumoniae

Viridans streptococci

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Group C strep

S. equisimilis,
S. zooepidemicus
S. equi

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Group G strep

S. arginosus

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STREPTOCOCCUS OF MEDICAL IMPORTANCE

pyogenes (A)
agalactiae (B)
pneumoniae
viridans
faecalis (D)

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Main human pathogen associated with local or systemic invasion and post – streptococcal immunologic disorders

Streptococcus pyogenes

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produces large (1cm in diameter) zones of β hemolysis around colonies greater that 0.5 mm in diameter

Group A β Hemolytic Streptococcus

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Its habitat skin and Upper Respiratory tract of humans, carried on nasal,
pharyngeal, sometimes anal mucosa

Streptococcus pyogenes

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Characteristic that has earned the designation ‘’flesh – eating bacteria”

Streptococcus pyogenes (Group A strep)

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Most strains of S. pyogenes produces capsules composed of____

hyaluronic acid

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S. pyogenes Fastidious, requires enriched media for primary isolation incubated with ______.

5% – 10% CO2

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Catalase negative (- )
PYR - positive (+)
Bacitracin: Sensitive

Streptococcus pyogenes

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Appears as circular, translucent, grayish to
opalescent colonies, matte or glossy large zone beta hemolysis

S. pyogenes

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test for Group A Streptococcus
demonstrate presence of pyrrolidonyl arylamidase

(+): development of a deep cherry red color
within a minute addition of reagent

PYR Hydrolysis Test (POSITIVE)

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Presumptive test for S. pyogenes

Used to differentiate Streptococcus pyogenes and Streptococcus agalactiae

RESULT:
S. pyogenes (sensitive)
S. agalactiae (resistant

Bacitracin Susceptibility Test

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use as basis for serological classification using Lancefield method

C - carbohydrate

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major virulence factor of group A S pyogenes. (most important virulence factor)

M – Protein

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obtained from streptococci by proteolytic digestion, which rapidly destroys M proteins.

permits differentiation of certain types of streptococci by agglutination with specific antisera,

T – Protein

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allows organism to cling to epithelial surfaces Cytotoxic; destroys rbc and wbc

Lipoteichoic Acid (LTA)

depolymerizes DNA; facilitate removal of purulent exudate/ discharges

Streptodornase (Streptococcal Deoxyribonuclease)

transforms the plasminogen of human plasma into plasmin, an active proteolytic enzyme that digests fibrin and other proteins

Streptokinase (Fibrinolysin)

An enzyme elaborated into the environment and is related to the organism's ability to kill leukocytes, PMN’s and macrophages.

Diphosphopyridine nucleotidase

(oxygen stable; non antigenic : surface BAP hemolysis during aerobic condition)

Streptolysin S

oxygen labile; antigenic) Immunogenic; responsible for some of the hemolysis seen when growth is in cuts deep into the medium in blood agar plates.

Streptolysin O

ASO serum titer in excess of ________ is considered abnormally high and suggests either recent infection with S. pyogenes

160–200 units

associated with streptococcal toxic shock syndrome and scarlet fever. -- act as superantigens

Erythrogenic Toxin

Most common cause of bacterial sore throat

PHARYNGITIS (Streptococcal sore throat)

Characterized by massive brawny edema and a rapidly advancing marin of infection

Erysipelas

surface is covered with pus and later is encrusted. honey colored crust

Impetigo (Sreptococcal pyoderma)

Follows infection associated with mild trauma, burns, wounds, or surgical incisions; pain, tenderness, swelling, and erythema occur. lesion is NOT raised, and the line between the involved and uninvolved tissue is indistinct. caused by Hyaluridinase

Cellulitis

characterized by shock, bacteremia, respiratory failure, and multiorgan failure; tends to follow minor trauma

Streptococcal Toxic Shock Syndrome

Occurs in association with S pyogenes pharyngitis or with skin or soft tissue infection

Scarlet Fever

develops 1–4 weeks after S pyogenes skin infection (pyoderma, impetigo); after random streptococcal skin infections, the incidence of nephritis is less than 0.5%.

Acute glomerulonephritis

Patients with more severe streptococcal sore throats have a greater chance of developing _________

Rheumatic fever

most serious sequela of S pyogenes because it results in damage to heart muscle and valves

Rheumatic fever

Streptococcus pyogenes : TREATMENT

Doses of Penicillin and Erthromycin Allergic Patient: Clindamycin, Erthromycin, Cephalexin

What bacteria. Habitat: Female genital tract and lower gastrointestinal tract Important cause of infection in OB/GYNE patient

Streptococcus agalactiae

major virulence factor of S. agalactiae

Sialic acid (sialic acid capsule)

HINT: B- BRAS CAMP test positive; hydrolyse sodium hippurate; Bacitracin Resistant; bile soluble; PYR Negative (–)

Streptococcus agalactiae

Test used to differentiate Group B strep (agalactiae) to S. aureus

CAMP test (+) arrow head beta hemolysis

Neonatal sepsis Neonatal meningitis Infections are associated with neonates acquired before or during the birthing process.

S. agalactiae

Direct Contact: person to person from mother in utero or during delivery; nosocomial transmission by unwashed hands of mother or health care personnel

S. agalactiae

Used to differentiate grp B streptococci from other beta hemolytic streptococci -- S. agalactiae possesses the enzyme hippuricase or hipurate hydrolase - (+) = purple color after addition of ninhydrin

Hippurate Hydrolysis test

contains the C polysaccharide unrelated to the Lancefield grouping

Streptococcus pneumoniae

AKA Frankel’s pneumococcus

Streptococcus pneumoniae

Colonizer of upper respiratory tract; Capable of spreading to the lungs, paranasal sinuses, and middle ear

Streptococcus pneumoniae

Gram + Lancet-shaped diplococci

Streptococcus pneumoniae

1. Test to swell the capsule 2. Stain used to stain the capsule

1. Quellung reaction 2. India ink stain

On blood agar resemble a doughnut

Streptococcus pneumoniae

Polysaccharide capsule – major virulent of _____

Streptococcus pneumoniae

BACTERIAL MENINGITIS S. pneumoniae SIGNS and SYMPTOMS appear within ________?

1 to 2 days after being exposed.

MOST COMMON bacterial pneumonia among elderly patient especially with COPD

LOBAR PNEUMONIAE

Clinical Manifestations: rusty colored sputum

Streptococcus pneumoniae

Most common cause of otitis media in children

S. pneumoniae

Test used to differentiate S. pneumoniae and viridans. Since both are alpha hemolytic

Optochin Test (letter P and disk)

S. pneumoniae optochin test result

(+) sensitive, susceptible, with ZOI

The most accurate and reliable specific method for IDENTIFICATION of S. pneumoniae

Newfiled Quellung test (capsular precipiation)

CONFIRMATORY test for S. pneumoniae

Bile Solubility Positive (+): absence of turbidity. After 3 hours of incubation reagent: Sodium desoxycholate (bile salts)

Inoculation of sputum with pneumonococci to susceptible animal. Observe after 16-24 hours, death occurs (+)

Mouse virulence test

used to detect the presence of antibodies against streptococci

Francis skin test

ENTEROCOCCI resistant to PCN

E. faecalis

ENTEROCOCCI grow 6.5% NaCl

E. faecium

ENTEROCOCCI grow in 40% bile

E. durans

have the group D group-specific substance

ENTEROCOCCI

Enterococci normal flora of the human GIT and female genitourinary tract

E. faecalis and Enterococcus faecium

Bile esculin positive (hydrolyze esculin) (deep blue ---> black pigmented colonies

ENTEROCOCCI

Culture media for isolation and cultivation of Enterococci

CAP

is the principal cause of dental caries (tooth decay).

S. mutans

Group-specific antigen extraction of Streptococcus pyogenes by treating with hydrochloric acid method is known as

Lancefield’s method

selective medium for Streptococcus pyogenes?

Crystal violet blood agar

Susceptibility to bacitracin can be used to identify

Streptococcus pyogenes

Test to differentiate Group B strep and Group A strep

Bacitracin test GroupB (-) resistant Group A (+) sensitive (ZOI) suso

Test to differentiate S. pneumoniae from viridans

Bile solubility test - (POSITIVE +) bile soluble / absence of turbidity Reagent: Sodium desoxycholate (bile salts)

ONLY GROUP _____ STREP WILL GROWN ON _____ TEST

Group B strep (+) on CAMP TEST

ASO, anti-DNase, antistreptokinase, and anti- hyaluronidase titers to detect past infection with

S. pyogenes

dental caries (tooth decay) and infective endocarditis are associated with WHAT streptococci

Viridans streptococci

Streptococci of this group are predominantly animal pathogens and comprise four species

group C streptococci. S. equi, S. equisimilis, S. dysgalactiae and S. zooep idemicus.

What strep group are commensals in the throats of human beings, monkeys or dogs.

group G streptococci

ASO titers higher than _____ Todd units/ mL are indicative of prior streptococcal infection.

200 Todd NOTE: High levels are usually found in acute rheumatic fever but in glomerulonephritis, titers are often low.

The _________ grow in the presence of 6.5% NaCl, 40% bile, at ph 9.6, at 45°C and in 0.1% methelyne blue

Enterococci

Pike’s medium contains what?

(blood agar containing 1 in 1,000,000 crystal violet and in 1 in 16,000 sodium azide)

Selective medium for Streptococcus pyogenes

PNF medium NOTE: The PNF medium which is the Selective medium for Streptococcus pyogenes can be prepared by incorporating Polymixin B Sulfate, Neomycin sulfate and Fusidic Acid in the Horse Blood Agar medium for the growth of Streptococcus pyogenes.

NOTE: For isolating group A streptococci from throat swabs the most common medium is blood agar supplemented with antibiotics trimethoprim/ sulfamethoxazole to suppress the groth of normal flora.

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what test is used to classify organisms in lancefield system

Lancefield precipitation test, also known as the Lancefield grouping test or the precipitin reaction.

Streptococcus Flashcards

(90 cards)