Module-2 Bacterial Growth & Diagnostics PDF

Module-2 Bacterial Growth & Diagnostics Chapter 7 Module-2 Assessments: KC-1 KC-2 Module-2 Quiz Case study group activity: Complete it as a group and submit a PowerPoint or Word Doc with your answers. Only one person in the group needs to submit. Make sure to include the names of all t...

Module-2 Bacterial Growth & Diagnostics Chapter 7 Module-2 Assessments: KC-1 KC-2 Module-2 Quiz Case study group activity: Complete it as a group and submit a PowerPoint or Word Doc with your answers. Only one person in the group needs to submit. Make sure to include the names of all the group members that participated. Learning Objectives Illustrate, label and explain the four phases of bacterial growth Describe how bacterial growth phases relate to disease progression Explain the importance of diagnostic tests in identifying pathogens, specifically: ○ Metabolic tests ○ Bacterial culturing ○ Antigen tests Bacterial Growth Limits to growth/multiplication of bacteria ○ Abiotic: temperature, availability of oxygen and water, etc. ○ Biotic: disease, competition, predation Bacterial Growth Phases Examination of the dynamics of bacterial growth reveals four major growth phases ○ Lag ○ Exponential/logarithmic ○ Stationary ○ Death Clinically relevant when discussing growth of microbes in humans leading to disease manifestation ○ I.e. E. coli incubating in the mayonnaise in the tuna salad at the beach on a warm day is ingested. Microbes begin to grow/multiply in your intestinal tract → leads to food poisoning. Bacterial Growth Phases Log Phase: cell population doubles with each generation/growth is exponential Lag Phase: Period of adaptation to new conditions Bacterial Growth Phases Stationary Phase: rate of cell division is about equal to rate of death. Nutrients depleted, toxins accumulate Death Phase: number of cells dying exceeds rate of cell division Significance of Bacterial Growth Growth during an infection mirrors the 4 stages ○ Lag - a few bacteria try and establish themselves at site of infection ○ Log - numbers of bacteria rising exponentially, see first signs and symptoms for that infection ○ Stationary - precipitated by success of host immune system or success of treatment ○ Death - bacterial numbers drop precipitously due to effect of immune system of treatment Microbial Generation Times Bacterial Diagnostics Culturing Bacteria: Diagnostics A clinical specimen is obtained to grow in culture to identify the suspected cause of infection ○ Inoculated into growth medium ○ Streaked across agar plate media to aid identification Colonies may have identifiable morphology or properties ○ Texture, size, pigment, hemolysis, etc. Culturing Bacteria: Diagnostics Metabolic tests are used to identify bacterial pathogens. Culturing Bacteria: Diagnostics Antigen Tests Rapid Strep antigen test ○ Identification of Streptococcus pyogenes Culturing Bacteria: Diagnostics A variety of media and diagnostic tests are available ○ Type selected depends on source of the specimen (bacterial pathogens of the skin may differ from those typically found in a vaginal swab, etc.) Some bacteria can’t be grown, or they grow too slowly, requiring alternative approaches ○ Detect specific anti-bacterial antibodies in patient’s blood ○ Amplification of pathogen’s DNA by PCR