Docstoc

链球菌检验-英

Document Sample
链球菌检验-英 Powered By Docstoc
					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
Classification
40 species and subspecies
Traditional rules
n    Hemolytic reactions
n    α hemolytic
n    β hemolytic
n    γ hemolytic

Lancefield serological tests
 n   A、B、C、D、E…
Clinical significant
Group A streptococci(S.
  pyogenes)

Impressive human pathogen
   Acute pharyngitis,respiratory
     infection
   Skin (impetigo and erysipelas)
     and soft tissue infection
 Endoarditis, meningitis,
 scarlet fever and more
 serious toxic shock-like
 symptoms

 Acute glomerulonephritis,
 rheumatic 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(SBE)
Streptococcus pneumoniae
  Community-acquired
  pneumonia, bacteremia

  Otitis media, sinusitis, meningitis,
  and endocarditis
Microbial Characters
       GPC
       Arranged:single,pairs,chains
       S. pneumoniae:
Facultatively anaerobe

Chemical reaction: active metabolism

Catalase:negative
Microbial diagnostics
  procedure
                  specimen


Smear and stain     culture direct examination


                     colony


Smear and stain   biochemical      serology       antibiotic
                  identification  identification susceptibility
返回
Microbial diagnostics
Specimen collection
  Throat swab, sputum, pus and blood, et al
Specimen direct diagnostics
  Smear and Gram stain
  Direct antigen detection
Culture and identification

 β hemolytic
   PYR test:Group A
   Bacitracin -
     susceptible :Group A
   VP(Voges-Proskauer )
     test
   CAMP test :Group B
 Non β hemolytic
Optochin test
Bile solubility test
Bile esculin test
Serologic tests:Streptolysin O
Antibiotic susceptibilities:A、B、C group
Evaluation, interpretation and reporting of
 results
  Beta-hemolytic streptococci and pneumococci
    are virulent pathogens, all reporting
  PRSP(penicillin resistant Streptococcus pneumonia)
Enterococcus

Common description
  Widespread in nature
  Gastrointestinal and genitourinary tract flora
  Hospital-acquired infection pathogen
Classification
  E. feacalis and E. faecium
Clinical significant
Urinary tract infections(UTIs):underlying
structural abnormalities and undergone
urologic manipulations
Abdominal and pelvic
   infections
sepsis
Microbial Characters
  GPC(single, pairs, short chains)
  Facultative anaerobes
  PYR test positive
  Higher resistance to chemical
   and physical agents
  Bile-esculin positive
  Resistance to several antibiotics
Microbial diagnostics
procedure
Specimen collection
Direct detection
Culture and
 identification
   Catalase negative
   Grow in 6.5% NaCl
    broth
   Bile-esculin positive
Antibiotic susceptibilities
   A group Penicillin or ampicillin
   B group Vancomycin
   C group Tetracycline, erythromycin,
     chlormphenicol, Rifampin
   D group Ciprofloxacin, Norfloxin
 high-level resistance(HLR) to aminoglycosides
   Enterococcus
   500ug/ml gentamicin   2000ug/ml streptomycin
 vancomycin resistant Enterococcus (VRE)
   6ug/ml vancomycin
Neisseria and Branhamella

Neisseriaceae
  Neisseria, Branhamella, Moraxella, Kingella and
   Acinetobacter
Mainly pathogens
  N. gonorrhoeae
  N. meningitidis
  B. catarrhalis
Clinical significant
  N. gonorrhoeae
   n   Common sexual transmitted diseases(STD)
   n   Transmitted by direct, close, usually sexual
   n   Transmission to neonates usually occurs
       during birth
virulence factor :pili
N. meningitidis
n   Meningitis, meningococcemia
n   Usually transmitted by direct contact with
    contaminated respiratory secretions or air-
    borne droplets
n   School-age children, adolescents, and young
    adults
B. catarrhalis
n   Acute localized infections: otitis media, sinusitis,
    and bronchopneumonia
n   Life-threatening systemic diseases: endocarditis
    and meningitis
Microbial Characters
Gram-negative diplococci
Adjacent sides flattened to give a characteristic
kidney or coffee bean appearance
Nonmotile,no endospores,some species are
encapsulated
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
  n   Direct microscopy
  n   Antigen and nucleate detection
Culture and identification

  Selective media:MTM,ML,NYC
  (N. gonorrhoeae )
  Nonselective media:Chocolate
  agar or blood agar
  5%CO2
Colonial appearance
   N. G:small,smooth
   N. M:small,smooth,flat,mucoid
   B. C:small, friable
Presumptive identification
n   GNC,OX+
Confirmatory identification
n   G.M:acid production from glucose and
    maltose
n   G.N:acid production from glucose
n   B.C:DNase +,nitrate reduction +




 (-)         (+)

       氧化酶

                       DNA酶试验          硝酸盐还原试验阳性
Antibiotic Susceptibilities

  Penicillin, cephalosporin、tetracycline、
  ciprofloxacin
  Resistant strains
     w G.N:3rd cephalosporins、new
       fluoroquinolone
     w B.C:extended-spectrum penicillin+
       penicillinase inhibitory
Evaluation, interpretation and
reporting results

  N.G
  confirm:depend on culture and
  identification
  Early and rapidly diagnosis
Summary
 Staphylococcus
 Streptococcus
 Enterococcus
 Neisseria and
 Branhamella
 Classification、Clinical Significance、Microbial Characters、Microbial
 diagnostics

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:5
posted:6/12/2014
language:English
pages:35