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Coccus Tao Chuan-min Tel:85422618 E-mail:taochuanmin@sina.com.cn

Coccus Tao Chuan-min Tel:85422618 E-mail:taochuanmin@sina.com.cn. Outline. Staphylococcus Streptococcus Enterococcus Neisseria and Branhamella Classification 、 Clinical Significance 、 Microbial Characters 、 Microbial diagnostics. Staphylococcus.

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Coccus Tao Chuan-min Tel:85422618 E-mail:taochuanmin@sina.com.cn

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  1. Coccus Tao Chuan-min Tel:85422618 E-mail:taochuanmin@sina.com.cn

  2. Outline • Staphylococcus • Streptococcus • Enterococcus • Neisseria and Branhamella • Classification、Clinical Significance、Microbial Characters、Microbial diagnostics

  3. Staphylococcus Gram-positive cocci that occur singly and in pairs, tetrads, and irregular grape-like clusters

  4. Common description • Widespread in nature • Mainly found living on the skin, skin glands and mucous membranes of mammals and birds • Also found in the environment • Sometimes found in the mouth, blood, and intestinal, and upper respiratory tracts

  5. Classification • Currently composed of 32 species and 15 subspecies • Important Staphylococcus • S. aureus • S. epidermidis • S. capitis • S. hominis • S. saprophyticus • Coagulase • Coagulase positive Staphylococci • Coagulase negative Staphylococci

  6. Clinical significant • S. aureus • Important pathogen • Enzymes:catalase, coagulase,staphylokinase, et al • Toxin: exotoxin, enterotoxin, et al • Community- and hospital acquired infection • Acute pyogenic infection • Common infection：boil、cellulitis、postoperative wound infections • Serious infection：bacteremia、pneumonia、osteomyelitis、meningitis，acute endocarditis, et al

  7. Osteomyelitis Abscess Impetigo School sores; common mostly among children Boils Infection of hair follicles by S. aureus

  8. Food poisoning: enterotoxin • Toxic shock syndrome(TSS)： • toxic shock syndrome toxin 1(TSST-1) • Scaled skin syndrome

  9. Coagulase negative staphylococcus, CONS • Normal flora of human • Causing nosocomial infections • S. epidermidis • Prosthetic valve endocarditis • Intravascular catheter-related infection • Peritoneal dialysis-related infection • Prosthetic joint infection • Why • The increase in the use of prosthetic and indwelling devices • Immunocompromised patients in hospitals • S. saprophyticus • Urinary tract infection

  10. Microbial Characters • Gram positive coccus • arranged：single、pairs、tetrads, short chains and grape-like clusters • Facultatively anaerobe • Colonial appearance • Color, smooth, entire, heamolytic characters • Chemical reaction: active metabolism,fermenting carbohydrates • Catalase：+(differentiates from streptococcus) • Coagulase: +/-

  11. Microbial diagnostics Isolated culture Broth culture • procedure specimen Smear and stain culturedirect examination colony Smear and stain biochemical serologyantibiotic identificationidentification susceptibility

  12. Specimen collection • Routine method • Avoid normal flora contamination • Surface swab, pus, blood, spinal fluid, sputum, et al • Specimen direct diagnostics • Smear and Gram stain • report • Culture and identification • Media selection • Blood agar • Broth • Selective agar

  13. Colonial appearance • S. aureus • Large,smooth,entire, slightly raised, pigment from cream-yellow to orange, β heamolysis • S. epidermidis • Small, smooth, entire, slightly raised, white, nonheamolysis

  14. Catalase • Staphylococcus produce catalase • Convert hydrogen peroxide into water and oxygen (formation of bubbles)

  15. Coagulase production Ability to clot plasma Rapid and economical test Dehydrated rabbit plasma containing EDTA Slide test • Bound coagulase＋plasmaclot(10s) • +: S. aureus and S. intermedius Tube test • Free coagulase Other: latex agglutination test

  16. Heat-stable nuclease +： S. aureus, S. schleiferi ,S. intermedius and S. carnosus Heat-stable staphylococcal nuclease (thermonuclease[TNase]) Method: metachromatic agar diffusion procedure and DNA-toluidine blue agar Phosphatase activity +：S. epidermidis, S. aureus, S. schleiferi andS. intermedius

  17. Pyrrolidonyl arylamidase activity (PYR test) principle: bacteria L-pyrrolidonyl-β-naphthylamideβ-naphthylamine 　　　　　　　　　　　　　　　 　＋ N,N-dimethylaminocinnamaldehyde red color

  18. Other Ornithine decarboxylase activity β-galactosidase activity Novobiocin resistance

  19. Antibiotic susceptibilities A class（routine antibiotic） oxacillin,penicillin B class（use mainly antibiotic in clinical） azithromycin,clindamycin,TMP/SMZ,vacomycin C class（resistant to A class） ciprofloxacin,gentamicin,chloramphenicol U class（bacteria from urine） norfloxacin, nitrofurantoin

  20. Methecillin resistant Staphylococcus, MRS MRSA、MRSE、MRSCO Main pathogen in nosocomial infection Resistant to oxacillin resistant：high resistant heteroresistant：borderline Two subpopulations coexist: one susceptible and the other resistant

  21. MRS Detection methods The presence of NaCl（2 to 4%） cooler temperatures (30 to 35 ℃) prolonged incubation(up to 48h) mecA gene probe PCR

  22. MRS Resistant mechanism • chromosome mecA gene mediated, produce low affinity penicillin binding protein(PBP), PBP2’ or PBP2a characters Multidrug-resistant Resistant to all β－lactams Clinical use Vacomycin, teicoplanin, ciprofloxin, TMP-SMZ, et al

  23. Summary Gram stain＋colonial appearance Catalase + +S. aureus _ coagulaseCONS Attention: MRS

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