Microbiology practical Flashcards
What key equipment is required for a zoonotic disease outbreak investigation in broiler chickens?
Essential equipment includes a stomacher, sterile containers, pipettes, Brilliant Green Agar plates, gloves, Howie lab coats, serial dilution materials (e.g., PBS), and microbiological safety cabinets for higher-risk activities.
What safety measures are critical during a zoonotic disease investigation in a lab?
Use Good Laboratory Practices (e.g., aseptic techniques, covering wounds, washing hands), wear appropriate PPE (gloves, lab coats), avoid working near electrical hazards, and dispose of waste correctly. Clean workspaces with disinfectants post-experiment.
How do you process chicken samples to isolate Salmonella?
Samples are stomached to homogenize the material, then subjected to ten-fold serial dilutions in PBS before being plated on Brilliant Green Agar for bacterial enumeration and incubation.
How are serial dilutions performed for pathogen isolation?
Add 0.1 mL of the sample to 0.9 mL of PBS in sequential steps to achieve dilutions of -1 to -4, ensuring accurate measurement with reverse pipetting to prevent splashing.
How do serotyping and genotyping help trace pathogens in outbreaks?
Serotyping identifies the specific antigenic profile of Salmonella strains, while genotyping analyzes the genetic material to establish relationships between strains from different sources, aiding in outbreak source identification.
What are reverse pipetting and its benefits during sample processing?
Reverse pipetting minimizes splashing and ensures accurate liquid handling by first drawing extra liquid into the pipette tip and dispensing only the required amount.
What are the steps in investigating a food source like an abattoir during an outbreak?
Collect and process samples (e.g., chicken neck skin), perform serial dilutions, plate on selective media, incubate, and examine for pathogens like Salmonella to assess links to the outbreak.
What is the purpose of slide agglutination in a zoonotic outbreak investigation?
Slide agglutination confirms the presence of Salmonella by using Poly-O antiserum, which reacts with the bacterial antigens to form visible granularity or clumping.
What key equipment is needed for a slide agglutination test?
A clean glass slide, sterile PBS, a sterile loop or pipette, Poly-O antiserum, and Brilliant Green Agar plates with isolated colonies.
What are the steps for performing slide agglutination with Salmonella?
How does serotyping help in tracing pathogens during an outbreak?
Serotyping identifies the antigenic properties of Salmonella, providing specific information about the strain, which helps trace the pathogen’s origin and its spread in the outbreak.
How does the confirmation of Salmonella colonies support outbreak investigations?
Confirming Salmonella helps establish a direct link between samples collected at the farm, abattoir, or food and the suspected outbreak, enabling targeted control measures.
What is granularity/clumping in slide agglutination?
Granularity or clumping indicates a positive reaction where Salmonella antigens bind with the Poly-O antiserum, confirming the presence of the pathogen.
