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