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Streptococcus
Tao Chuanmin
Widespread in nature
Some strains as virulent pathogens
Other strains live harmoniously
Transient colonizers of skin
Resident colonizer of mucous membranes
Normal flora of alimentary, respiratory and genital tracts
Classification40 species and subspecies
Traditional rules Hemolytic reactions
α hemolytic
β hemolytic
γ hemolytic
Lancefield serological testsA 、 B 、 C 、 D 、 E…
Clinical significantGroup A streptococci(S. pyogene
s)
Impressive human pathogen
Acute pharyngitis,respiratory inf
ection
Skin (impetigo and erysipelas) an
d soft tissue infection
Endoarditis, meningitis, sca
rlet fever and more serious t
oxic shock-like symptoms
Acute glomerulonephritis, r
heumatic fever
Numerous virulence factors
M protein, Pyrogenic exotoxins, Hyaluronic acid capsule, Hemolysins etc.
Group B streptococci(S. agalactiae) Neonatal infection
sepsis and meningitis
Group C and G streptococci
Similar to S. pyogenes
Viridans Streptococci
Normal flora
Subacte bacterial endocaditis(S
BE)
Streptococcus pneumoniae
Community-acquired pneumonia,
bacteremia
Otitis media, sinusitis, meningitis,
and endocarditis
Microbial Characters
GPCArranged : single,pairs,chains
S. pneumoniae :
Facultatively anaerobe
Chemical reaction: active metabolism
Catalase : negative
Microbial diagnosticsprocedure
specimen
Smear and stain culture direct examination
colony
Smear and stain biochemical serology antibiotic
identification identification susceptibility返回
Microbial diagnostics
Specimen collectionThroat swab, sputum, pus and blood, et al
Specimen direct diagnosticsSmear and Gram stain
Direct antigen detection
Culture and identification
β hemolytic PYR test : Group ABacitracin-susceptible :
Group AVP(Voges-Proskauer) t
estCAMP test : Group B
Non β hemolyticOptochin test
Bile solubility test
Bile esculin test
Serologic tests : Streptolysin O
Antibiotic susceptibilities : A 、 B 、 C grou
p
Evaluation, interpretation and reporting of re
sultsBeta-hemolytic streptococci and pneumococci ar
e virulent pathogens, all reporting PRSP(penicillin resistant Streptococcus pneumonia)
Enterococcus
Common descriptionWidespread in nature
Gastrointestinal and genitourinary tract flora
Hospital-acquired infection pathogen
ClassificationE. feacalis and E. faecium
Clinical significant
Urinary tract infections(UTIs) : underlying structural abnormalities and u
ndergone urologic manipulations
Abdominal and pelvic
infections
sepsis
Microbial CharactersGPC(single, pairs, short chains)
Facultative anaerobes
PYR test positive
Higher resistance to chemical and physical agents
Bile-esculin positive
Resistance to several antibiotics
Microbial diagnosticsprocedure
Specimen collection
Direct detection
Culture and identific
ation
Catalase negative
Grow in 6.5% NaCl
broth
Bile-esculin positive
Antibiotic susceptibilitiesA group Penicillin or ampicillin
B group Vancomycin
C group Tetracycline, erythromycin, chlormphenic
ol, Rifampin
D group Ciprofloxacin, Norfloxin
high-level resistance(HLR) to aminoglycosides En
terococcus
500ug/ml gentamicin 2000ug/ml streptomycin
vancomycin resistant Enterococcus (VRE)
6ug/ml vancomycin
Neisseria and Branhamella
Neisseriaceae
Neisseria, Branhamella, Moraxella, Kingella and Acinet
obacter
Mainly pathogens
N. gonorrhoeae
N. meningitidis
B. catarrhalis
Clinical significant
N. gonorrhoeae Common sexual transmitted diseases(STD)
Transmitted by direct, close, usually sexual
Transmission to neonates usually occurs durin
g birth
virulence factor :pili
N. meningitidis Meningitis, meningococcemia
Usually transmitted by direct contact with conta
minated respiratory secretions or air-borne dro
plets
School-age children, adolescents, and young adu
lts
B. catarrhalis Acute localized infections: otitis media, sinusitis,
and bronchopneumonia
Life-threatening systemic diseases: endocarditis
and meningitis
Microbial Characters
Gram-negative diplococci
Adjacent sides flattened to give a characteristic kidn
ey or coffee bean appearance
Nonmotile , no endospores , some species are enc
apsulated
Cell may autolyze in culture
Complex growth requirements
aerobe
The growth is enhanced by humidity and CO2
Oxidase positive
catalase positive
Microbial diagnostics
Procedure
Collection
Direct detection Direct microscopy
Antigen and nucleate detection
Culture and identification
Selective media : MTM , ML , N
YC ( N. gonorrhoeae )Nonselective media : Chocolate agar or blood agar5%CO2
Colonial appearance
N. G : small,smooth
N. M : small,smooth,flat,mucoid
B. C : small, friable
Presumptive identification GNC , OX+
Confirmatory identification G.M : acid production from glucose and malt
ose G.N : acid production from glucose B.C : DNase + , nitrate reduction +
DNA 酶试验 硝酸盐还原试验阳性
(-) (+)
氧化酶
Antibiotic Susceptibilities
Penicillin, cephalosporin 、 tetracycline 、ciprofloxacin
Resistant strains G.N : 3rd cephalosporins 、 new fluoroqui
nolone B.C : extended-spectrum penicillin + pen
icillinase inhibitory
Evaluation, interpretation and reporting results
N.G
confirm : depend on culture and
identification
Early and rapidly diagnosis
Summary
Staphylococcus
Streptococcus
Enterococcus
Neisseria and
BranhamellaClassification 、 Clinical Significance 、 Microbial Characters 、 Micro
bial diagnostics