Streptococcus Part 2 Flashcards
• Normal flora of the GIT & Vaginal tract
• Gram positive cocci in chains
• Beta hemolytic in BAP
Group B: Streptococcus agalactiae (GBS)
Component of Group B: Streptococcus agalactiae (GBS)
• Anti-phagocytic
• inhibits complement activation
• able to mimic host molecules, enhancing pathogenicity.
polysaccharide capsule
Pathogenesis and Clinical Manifestations
S. agalactiae
2 types
• Neonatal Infection: pneumonia, meningitis & sepsis
Early onset - 1st week of life
Late onset - after 1st week to 3rd month of life
S. agalactiae
Adult Streptococcal infection:
Mostly nosocomial
Immunocompromised
host
• Skin & soft tissue infections
• Pneumonia
• Septic arthritis
• Bacteremia
• UTI
• endocarditis
GBS: S. agalactiae
Diagnostic Laboratory Tests
- CAMP Test
- SODIUM HIPPURATE HYDROLYSIS
CAMP Test
• Christie, Atkins and Munch-Peterson
GBS: S. agalactiae DIAGNOSTIC test
• ВАР
• Do not incubate anaerobically or with increase CO2 to prevent false reaction
CAMP Test
Positive indicator for CAMP
(+)= Arrowhead zone of remolysis
SODIUM HIPPURATE HYDROLYSIS
Procedure:
0.4 ml 1% Na hippurate
+
loopful of organisms
(incubate 32°C for 10 mins.)
+
0.2ml ninhydrin solution
(reincubate 37° for 10 mins)
=
(+) deep purple color
Group C, F & G: Miscellaneous Beta Hemolytic Streptococcus
•______-hemolytic streptococci
• Normal microbiota:
• Endogenous strain:
• Direct contact:
beta
skin, nasopharynx, GIT, GUT
gain access to sterile site
person to person
Group C, F & G: on 5% Sheep Blood Agar
• B-hemolytic
streptococci
• Grayish white, glistening;
• wide zone of B-hemolysis
Group C
Group C, F & G: on 5% Sheep Blood Agar
• B-hemolytic
streptococci
• Grayish white, small, matte;
• narrow to wide zone of B-hemolysis
Group F
Group C, F & G: on 5% Sheep Blood Agar
• B-hemolytic
streptococci
• Grayish white, small, matte;
• narrow to wide zone of B-hemolysis
Group F
Group C, F & G: on 5% Sheep Blood Agar
• 8-hemolytic streptococci
• Grayish white, matte;
• wide zone of B-hemolysis
Group G
Group C & G
• S. equi subsp. zooepidemicus,
• S. equi subsp. equi
• S. dysgalactiae subsp. equisimilis,
• S. dysgalactiae subsp. dysgalactiae
• S. anginosus
• Cause infection similar to Group A
• Pharyngitis, skin & soft tissue infections, and bacteremia
Group C & G
Group C, F & G: Species & Diseases
• S. anginosus
• Cause cellulitis
• abscesses
• bacteremia
Group F
Group C, F & G: Identification
• Negative:
• Susceptible to
• S. dysgalactiae subsp. equisimilis =
• S. anginosus (C,G,F) =
CAMP, PYR, Bile Esculin Hydrolysis, Hippurate
SXT
Vp (-); Vp(+)
Group C, F & G: Identification
Biochemical reaction & serological testing
• Serological test:
• Extract + antisera (with latex beads for visualization)
• Observe for AGGLUTINATION
Streptococcus pneumoniae :
GENERAL CHARACTERISTICS
• Gram(+) diplococci
• Requires____ → Capnophilic
•[capsule??], non-motile, non-spore forming
•[growth condition???], fastidious
•____-hemolytic
5 to 10% CO2
encapsulated
facultative anaerobe
alpha
Streptococcus pneumoniae :
GENERAL CHARACTERISTICS
• Gram(+) diplococci
• Requires____ → Capnophilic
• [capsule???], non-motile, non-spore forming
•[growth condition???], fastidious
•____-hemolytic
5 to 10% CO2
encapsulated
facultative anaerobe
alpha
Streptococcus pneumoniae :
MAJOR VIRULENCE FACTORS
• CAPSULAR ANTIGENS
- M-CHON
• PNEUMOLYSIN
• Autolysin
Streptococcus pneumoniae :
MAJOR VIRULENCE FACTORS
• immunologically distinct for each type
• Resist phagocytosis
CAPSULAR ANTIGENS
Streptococcus pneumoniae :
MAJOR VIRULENCE FACTORS
M-CHON:
Type-specific CHON antigens
Streptococcus pneumoniae :
MAJOR VIRULENCE FACTORS
• released in cell lysis, hemolytic
• Antiphagocytic, Activates complement
PNEUMOLYSIN
Streptococcus pneumoniae :
MAJOR VIRULENCE FACTORS
•: aids in the release of pneumolysin
Autolysin
Streptococcus pneumoniae : EPIDEMIOLOGY, PATHOGENESIS & CLINICAL MANIFESTATIONS
• RT → sinuses & middle ear →______
sinusitis & otitis media
Streptococcus pneumoniae : EPIDEMIOLOGY, PATHOGENESIS & CLINICAL MANIFESTATIONS
DISEASE:
• pneumonia, bacteremia, & meningitis
• community-acquired bacterial pneumonia;
• most common in U.S. (rusty sputum)
Streptococcus pneumoniae
Streptococcus pneumoniae : MOT
• person to person contact
• respiratory droplets
Diagnostic Laboratory Tests
1. MICROSCOPIC:
S. Pneumoniae
• Gram(+) lancet-shaped diplococci
S. pneumoniae
- CULTURE:
BAP:______, @_____
• wide zone of__-hemolysis (aerobically)
• MORPHOLOGY???
Colonies later develop a “____“-like appearance
5-10% CO2; 35-37 C (24 hrs.)
Alpha
Mucoid, dome shape, transparent colonies
crater
S. Pneumoniae LAB Diagnosis
Optochin Test/ Taxo P:
Bile Solubility Test:
Quellung Test:
Optochin Test/ Taxo P:
•reagent:_______
=______[suscpetibilty]
Ethylhydrocupreine HCI (5 ug)
v (+)
14mm or more, Susceptible
Bile Solubility Test:
*reagent: Bile salts (Na deoxycholate; Na taurocholate)
v (+).
Positive: ____
autolysis (clear solution)
Quellung Test:
Swollen capsule (Ag-Abreaction)
S. pneumoniae
TREATMENT
• Acquired resistance to penicillin, macrolides, & cephalosporins
• Sensitivity testing is necessary → TREATMENT
• Penicillin, ceftriaxone/cefotaxime, tmp/smx (STX)
S. Pneumoniae
PREVENTION
•
Pneumococcal conjugate vaccine
Streptococcus bovis group :
GENERAL CHARACTERISTICS
→ single species
• S. bovis & S. equinus
S. bovis
• Others
: S. gallolyticus, S. infantarius, S. alactolyticus
S. bovis
• Characteristics:
• Lancefield Group____
• Bile esculin____ PYR___
• Unable to grow in_____
• Alpha or gamma hemolytic
D
(+); (-)
6.5% NaCl broth
S. bovis
• Diseases:
Bacteremia, septicemia, endocarditis
S. bovis
• Diseases:
Bacteremia, septicemia, endocarditis
Enterococcus group :
GENERAL CHARACTERISTICS
• Lancefield group___ Antigen
D
Enterococcus
• Species:
• E. faecalis
• E. faecium
• E. durans, E. avium, E. casseliflavus, E. gallinarum, E. dispar, & E. canis
Enterococcus group :
GENERAL CHARACTERISTICS
•_________ on SBA
• may be found in the environment
• Normal flora of_______
• Nosocomial infections
Alpha or non hemolytic
GIT, skin, oral cavity, & GUT
Enterococcus
High risk: immunocompromised, patients with invasive procedure, & prolonged antibiotic treatment
• immunocompromised, patients with invasive procedure, & prolonged antibiotic treatment
Diagnostic Laboratory Tests
Diagnostic Laboratory Tests
Name of the test:______
Example A: Positive - Group D streptococcus (Enterococcus species)
Example B: Negative - Group B streptococcus
Bile Esculin test
The selective agent Die, innions most gram positive bacteria
Acid family far
in the medium is hydrolyzed to esculetin and dextrose
The_____ reacts with ferrie chloride in the media to form a _____color.
Esculin
esculetin
black-brown
Diagnostic Laboratory Tests
• Purpose:
• Differentiate Enterococcus from
Streptococcus bovis group which are intolerant
6.5% SALT BROTH OR SALT TOLERANCE TEST
6.5% SALT BROTH OR SALT TOLERANCE TEST
• Principle:
• If growth is present in both broth (w/ salt & w/o salt), the organism is salt tolerant.
FACTS:
• has intrinsic resistance to beta lactam antibiotics
• Combination treatment: beta lactam (penicillin or vancomycin) with aminoglycosides
• Vancomycin resistant Enterococci (VRE) → first reported in 1986
Enterococcus
Viridans
• S. mutans
• S. salivarius
• S. mitis
• S. sanguinis
• S. constellatus
• S. intermedius
VIRIDANS GROUP
BAP:
a-hemolytic w/ greenish discoloration
Normal flora of the human oropharynx, GIT & female genital tract
Viridans
Viridans
• Diseases:
> subacute bacterial endocarditis
Bacteremia & septicemia
Dental caries
VIRIDANS GROUP: Laboratory Diagnosis
_____to bile (sodium deoxycholate), & _____optochin to most presumptive tests for Streptococcus
_____to mannitol & sorbitol
_____to urease & VP reaction
Resistant
Negative
Positive
Positive
= requires cysteine or pyridoxal (vitamin B6) for growth
NUTRITIONALLY VARIANT STREPTOCOCCI (NVS)
= Given the new genus Abiotrophia & Granulicatella
NUTRITIONALLY VARIANT STREPTOCOCCI (NVS)
Other Catalase (-) Streptococcal Like
Organisms
Aerococcus viridans
Leuconostoc spp.
Pediococcus
Leuconostoc & Pediococcus
Lactococcus & Gemella
• rare cause of endocarditis & meningitis Intracerebral hemorrhage (ICH)
Aerococcus viridans
• NF of LGIT, isolated occasionally from abscesses
Pediococcus
Leuconostoc & Pediococcus
• exhibit resistance to____
Vancomycin
Summary of Laboratory Diagnosis: GAS
• Wide zone of beta hemolysis
• Bacitracin
• PYR
• SXT
• CAMP
susceptible
positive
resistant
negative
Summary of Laboratory Diagnosis: GBS
• beta hemolysis (narrow zone)
• CAMP _____
• Hippurate ____
• Bacitracin____
• SXT ____
• PYR_____
• Bile-esculin hydrolysis _____
positive
positive
resistant
resistant
negative
negative
Summary of Laboratory Diagnosis:
Pneumococci
• Optochin Test/ Taxo P: (+)
• Bile Solubility Test:
• Quellung Test:
14mm or >
autolysis (clear solution)
swollen capsule
Group D Enterococcus
Bile- Esculin media
6.5% NaCl
PYR
+
+
+
Group D Non-Entero-coccus
Bile- Esculin media
6.5% NaCl
PYR
-
Not Group D
Bile- Esculin media
6.5% NaCl
PYR
-
Treatment
(GAS; also, pneumococci)
• Penicillin G
Treatment
(TSS)
Clindamycin
Treatment
(enterococci, pneumococci)
Ampicillin or vancomycin
Treatment
(pneumococci)
(meningitis)
• 1st gen. cephalosporin
• 3rd generation cephalosporin with or without vancomycin
T or F
Most are sensitive to Erythromycin
True
