M4A1: Create Your Own Bacterial Key

Throughout the previous modules you have gained information on the methods used to distinguish different bacteria from one another. This activity serves to reinforce the concepts associated with biochemical tests, help you learn the metabolic strategies associated with individual or groups of bacteria, and strengthen your understanding of basic morphological differences. For this assignment, you are to choose one (1) of the groups, either A) oral/respiratory tract pathogens and commensals, or B) urogenital pathogens and commensals or C) gastrointestinal tract pathogens and commensals, and develop a key based on differential staining and culturing, morphology and the suite of biochemical tests available to identify bacteria.

A) Typical oral/respiratory tract pathogens and commensals -

Streptococcus pneumonia 

Yersina pestis

Haemophilus influenza

Streptococcus viridans

Staphylococcus aureus

Bacillus antracis

Klebsiella pneumonia

Bordetella pertussis

Streptococcus pyogenes

Chlamydia pneumonia

Psuedomonas aeruginosa

Mycobacterium tuberculosis

Mycoplasma pneumoniae

B) Typical urogenital pathogens and commensals

Neisseria gonorrhoeae

Streoticiccus agalactiae

Staphylococcus saprophyticus

Clostridium perfringens

S. pyogenes

Haemophilus vaginalis

Ureaplasma urealyticum

Treponema pallidum

Chlamydia trachomatis

Serratia marcescens

Trichomonas vaginalis

C) Typical gastrointestinal pathogens and commensals -

Campylobaacter jejuni

Enterobacter faecalis

Salmonella typhimurin

Shigella sonnei

Escherichia coli

Bacillus cereus



Clostridium perfringens

Vibrio cholerae



C. dificile

Helicobacter pylori



Alcaligenes faecalis

Listeria monocytogenes


Use the uploaded file example for a guide to the problem solving