Experiment 4 Identification of pathogenic bacteria

Content  Identification of Pathogenic Cocci from Clinical Specimen  Coagulase Test  Identification of Intestinal Pathogens from Feces  Identification of bacteria in throat

Identification of Pathogenic Cocci from Clinical Specimen

N. gonorrhoeae N.meningitidis S. pneumoniaestaphylococcusStreptococcus Pathogenic Cocci N.meningitidis

Pus Throat swab smear 、 Gram stain 、 observe Blood agar Colonies observation 37 ℃ 24h Identification of Pathogenic Cocci from Clinical Specimen Biochemical reaction, Pathogenicity test

A presumptive diagnosis of meningococcal meningitis can be made if gram-negative cocci are seen in a smear of spinal fluid The finding of gram-negative diplococci within PMNs in a urethral discharge specimen is sufficient for diagnosis

Identification of staphylococcus Staph. Aureus Staph. pidermidis Pigmentation Golden yellow White α- Hemolysin + - Coagulase + - Heat-stable nuclease test + - Mannitol fementaion test + - pathogenisis significant weak or none

Small colonies 、 translucent 、 smoth 、 neat margin G+ 、 arranged in strain beta-hemolytic streptococci Clear zone beta-hemolytic streptococci gamma-hemolytic streptococci No zone gamma-hemolytic streptococci alpha-hemolytic streptococci Green zone alpha-hemolytic streptococci synanthrin - （ violet ） + （ yellow ） fermentation test Bile-soluble test - （ clouding ） + （ clear ） alpha-hemolyticstreptococci streptococcuspneumoniae Identification of Streptococcus

Coagulase Test Coagulase: Any bacterial component or product which causes coagulation in plasma containing an anticoagulant such as citrate, heparin or oxalate. Staphylocoagulase. free coagulase (detected in tube) Bound coagulase (detected in slide) pathogenic staphy. Aureus produces coagulase, while non-pathogenic strains are coagulase negative

Coagulase Test NS Staphy. Aureus plasma

Biochemical Reaction Carbohydrate fermentation methyl red test Voges-Proskauer test citrate utilization test Sulfide ( H 2 S ) production Indole production Urea hydrolysis

fermentaton test

methyl red test - +

VP （ Voges-Proskauer ） test

－ + + -

H 2 S Production Urease Test

Indole Test; Methyl Red (MR) Test; Voges-Proskauer (VP) Test; Citrate Utilization Test E.coli ＋ ＋ － － gas Bacillus － － ＋ ＋

Identification of Intestinal Pathogens from Feces

Selective medium---- Salmonella-Shigella agar plate (S-S plate) Pathogenic bacilli---lactose fermentaiong(-) small colonies, colorless, Nonpathogenic bacilli-- lactose fermentaiong (+) large colonies, red ，

Pathogenic bacilli-- lactose fermentaiong (- ) Small colonies, colorless Nonpathogenic bacilli-- lactose fermentaiong(+ ) Violet-black colonies Differential medium ---- EMB （ Eosin Methyl Blue)

Double sugar iron agar slant inoculatin observe –upperlayer Lactose fermemtation ： pathogenic bacilli—red, nonpathogenic bacilli--yellow H 2 S –underlayer Glucose fermemtation （ acid, gas ） motivation lactose Fe 2 SO 4 solid glucose Semi-solid Indicator: phenol red

Specimen Streak on SS agar plate Biochemical reaction Serologic test double sugar iron agar Agglutinate with polyvalent antisera against Salmonella & Shigella 37 ℃ 24h ? Different with cocci

lactose glucose motivation H2S E.coli ⊕ 黄色 ⊕ + - Shigella - 红色 S.typhi - 红色 + + +/- Identification of enteric bacilli

实验材料 玻片 2 个 / 人，金黄色葡萄球菌、大肠杆菌 1 管 / 小组，血浆 1 管 / 小组 革兰染液 1 套 / 小组

Report-- C oagulase test (detected in slide) I dentification of bacteria in throat principle procedure result analysis