Chapter 24 Data Sheet: Human Microbiology

Chapter 24 Data Sheet: Human Microbiology

Record your data

1. Blood agar plate
2. Describe the growth you have on the blood agar in terms of hemolysis patterns. What hemolysis patterns are evident? Which pattern is most common?
3. Select two colonies from your blood agar plate and describe them.Are either of these colonies Streptococcus or Staphylococcus? How would you know?

1. TSA plate (skin) – select 4 colonies
2. Describe what these bacteria look like in a simple stain.
3. Perform a catalase test on each. Record as + or –
4. What (tentative) identification can you make?

1. EMB plate (enteric) – select two colonies
2. Describe the growth on your EMB plate. What do the colonies look like?
3. Record your results for the citrate, SIM and TSI test
4. What (tentative) identification can you make for the 2 colonies you tested?

1. MSA plate (nose) – select one colony
2. Describe the color of your MSA plate: (pink / red / orange / yellow)

1. Stain bacteria from one colony. Describe stain:

1. Perform a coagulase test if you have a colony on yellow agar. Record data:

Questions for review

1. List some common resident microbes found on/in:

Human skinHuman throatHuman intestinal tract

1. What types of microbes are most common on skin? Why?

1. How do the colonies of the following skin bacteria differ?

1. Bacillus
2. Corynebacterium
3. Micrococcus luteus
4. S. aureus
5. S. epidermidis

1. What is the purpose of Mannitol Salt Agar? What type of microbe does MSA detect?

1. Distinguish/describe what is meant by alpha, beta and gamma hemolysis. Name 2 bacteria for each of these that can cause each kind of hemolysis.

1. How would you distinguish Streptococcus (an indication of Strep throat) from Staphylococcus (probably a contaminant from skin)? [both cause beta-hemolysis]

1. List some common pathogens that might be found in the human throat.

1. What type of medium is EMB? How does it enable you to distinguish E. coli (lactose-fermenting) from Salmonella (lactose-negative)?

1. What is the human intestine like in terms of habitat? What factors limit microbial growth there?

1. Name some common intestinal pathogens.

Table 1: Characteristics of common intestinal bacteria