The document discusses various methods for classifying and identifying bacteria, including:
1. Gram staining to differentiate bacteria based on cell wall structure.
2. Colony morphology, growth characteristics, and specialized tests to further classify bacteria.
3. Molecular diagnosis techniques like PCR, DNA hybridization, and microarrays that can identify bacteria faster and more definitively than conventional culture-based methods.
37. Biosensor Mediated Pathogen Detection Step 1: Attach Capture Antibody to Fiber Optic Waveguide Step 2: Apply Sample. Target Organism Binds to Waveguide Step 3: Wash Away Other Cells and Debris Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
38. Step 1: Attach Capture Antibody to Fiber Optic Waveguide Step 2: Apply Sample. Target Organism Binds to Waveguide Step 3: Wash Away Other Cells and Debris Step 4: Add Specific Detection Antibody Step 5: Turn on Laser. Detection Antibody Fluoresces, Indicating a Positive Sample. Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Biosensor Mediated Pathogen Detection Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
39. Biosensors Analyte 2000 TM for laboratory research and development RAPTOR TM automated version for field analysis
44. Gram negative Straight rods Curved rods Lactose+ Lactose- Citrate+ Citrate- H 2 S+ H 2 S- Klebsiella E.coli Salmonella Shigella Campy blood agar 42 o C+ 25 o C- Campylobacter TCBS agar Yellow Oxidase+ Vibrio
45. Bacteria Gram+ Cocci Rod Staph. Strep. Non-spore Spore S. a. S. e. S. s. A B Pn Vir Fil Rod A.i. C.d. L. m. +O 2 -O 2 B.a. B.c. C.b. C.t. C.p. C.d. Acid Fast M.t. M.l. N.c. Intra Cellular Rickettsia Coxiella Erlichia Chlamydia Wall Less Mycoplasma Gram- Cocci Rod Spiral Straight Curve +O 2 -O 2 +/-O 2 Other Treponema Borrelia Leptospira Neisseria Moraxella P.a. Enteric Bact. Resp. Zoo GU Bordetella. H. influenzae Legionella Yersinia Pasteurella Brucella Francislla Streptobacillus H. ducreyi Gardnerella Calymmatobacterium Vibrio Campylobacter Helicobacter
Editor's Notes
Chlamydia: No peptidoglycan or murimanic acid, does not stain well with Gram stan (use Giemsa stain)
Aerobic: SOD and catalase positive (important for survival) Mouth full of both aerobics and anaerobics (ask why?) Microaerophilics: H. pylori discovery story (2005 Nobel Prize in Medicine) Endospores are formed by certain Gram positives--to overcome adverse growth condition (B. anthracis) Exospores formed by fungi are for the purpose of replication TCBS medium for Vibrio (enrich and differentiate)
Yellow color by S. aureus de[ends on culture media Seritia marcesens: red pigment MacConkey: bile salt kills Gram positives EMB: eosin-methylene blue agar, select for enterics (mechanism?), differentiate lac+/- Mannitol salt: high salt (7.5% NaCl) select for certain bacteria, especially Staphylococcus sp., differentiate mannitol+/- Thyayer-Martin medium: contains several antibiotics, select for Nieseria.
Extreme cases, single cell bacteria can form fruiting body (any pathogenic bacteria form this???)
Different growth media may also affect the colony morphology
Ask “what is the function fo the capsules?”--antiphagocytic Shown is B. anthracis (most pathogen that cause systemic/blood stream infections have capsule to protect itself) Klebsialla, P. a., S. pneumonia etc.
Original plate is purple color (color of pH indicator) Lac+ turns pink (low pH) Lac- show no color (neutral pH) Contains bile salt, only allow Gram negatives to grow
Bacteria secrete protein or metabolites that lyse red blood cells.
Mannitol salt agar inoculated with (clockwise from upper left) Staphylococcus aureus showing fermentation of mannitol (yellow medium), Staphylococcus epidermidis showing growth but no fermentation of mannitol (pink medium), and Escherichia coli showing no growth. Mannitol Salt Agar (MSA) is a selective and differential medium. The high concentration of salt (7.5%) selects for members of the genus Staphylococcus , since they can tolerate high saline levels. Organisms from other genera may grow, but they typically grow very weakly.MSA also contains the sugar mannitol and the pH indicator phenol red. ハ If an organism can ferment mannitol, an acidic byproduct is formed that will cause the phenol red in the agar to turn yellow. Most pathogenic staphylococci, such as Staphylococcus aureus , will ferment mannitol. ハ Most non-pathogenic staphylococci will not ferment mannitol.
Pathogenic enteric are Lac- (important distinction from non-pathogenic enteric) Citrate slant agar: distinguish two commonly seem Gram negative rods (E.coli vs. Klebsiela) H2S: important in distinguishing Salmonella(+) from Shigella(-)
Early: glucose utilization (contains low amount of glucose) Later: if continue to utilize lactose or sucrose, pH keep low. If not (utilize proteins in the medium), then pH returns to neutral (color changes) Also, FeS form dark brown color Gas formation cal also be seen Aerobic and anaerobic growth can be seen
Catalase: H2O2---H2O + O2 Oxidase: important distinction of N.g from other Gram negatives cocci Urease: breath test for H. pylori Antibiogram: Bacitracin, optochin Fatty acid profile: seems not affected by growth conditions
Color is from indole molecule
For enteric identification
Phages use different receptors for infection, thus important indicator of presence or absence of particular receptor on the cell surfaces.
Ag-Ab complex formation (precipitation)
Embedded Ab conjugated with gold nanoparticle(visible red color) Diffusion of the complex
Ribotyping: chromosomal DNA digest with restriction enzymes, then probe with rRNA sequences
Distinguish different isolates (source of infections)
UAMS neonatal intensive care unit: Five children infected with S. aureus, searching for the source of the infections. Used collagen adhesin as probe (Southern blot)
Often used in detection of viral infections (intracellular)
Primer binding specificity determines if there will be PCR products The length of the PCR product is an important indicator Requires low amount of sample, sensitive and fast.
Two levels of specificity (1) Binding of the TaqMan probe (2) binding of the PCR primers Therefore, provide highly specific and real time result
Rapid Amplification of polymorphic DNA: Use single short primer (9bp) to do PCR Arkansas Children’s Hospital (1997): 3children died of P.a. infections within 2 wk. Ask if they are infected by the same strains? Source? The three kids (#3,4,5) were infected with the same strains, but the source was not found from the hospital environment. Predicted from nurse, but did not look for further (Boston Children’s hospital in 1990, 8 children died within 1month, found nurse had swimmer’s ear infection. After identification, the nurse tried to committee suicide) Learned the lesson, educate nurses for hand washing practice.
Depends on the specific nucleotide-nucleotide hybridization (sequence specificity) Specific Ab-Ag binding
Chip for pathogen identification (bacterial, viral and fungal) Also, disease markers such as cancer markers
For DNA, there are single target sequence per pathogen, while singel pathogen may have multiple copies of Ag (gene product)--more sensitive??
Bacitracin: acyclic dodecapeptide antibiotic produced by Bacillus sp. Optochin: Ethylhydrocupreine hydrochloride (EHC) (source?)