To think about....

Why would you recommend to a friend that he places 5, 10 and 20 cent
coins in his pet’s water bowl?
Why can someone get very ill from eating a lot of cold meats all at once?
Why is silver nitrate put into the eyes of newborns?

TRANSMISSION OF DISEASE

Categorised as either vehicle, vector and contact
Vehicle is non living
Vector is living
Contact is you know???
Mechanical vehicle is the insect itself ex allergy to bee sting
Biological vehicle is when part of life cycle of pathogen is inside insect ex malaria
Example of Waterborne vector is cholera
For pathogens to be transmitted though air, the distance must be less than 1 meter
Foodborne pathogen transmitted through cooking utensils, food itself, etc
Direct contact is kissing, sex
Indirect contact is through fomites
Droplets are when nasty people sneeze and cough directly on you

Media tut questions

Choose the odd one out, and justify your choice
1. Peptone, asparagines, L cysteine, glucose
2. Malachite green, glycerol, asparagines, methylene blue
3. Ferric citrate, magnesium citrate, ferric ammonium citrate
4. Increased dextrose, Proteus, decrease Ph, Rhizopus
5. Rabbit blood, trimethoprim, penicillin, Bordet Gengou
6. Sterile mineral oil, closed, Pseudomonas, fermentative
7. Trimethoprim, vancomycin, nystatin, colistin
8. Ox bile, brilliant green, K tellurite, blood
9. Bile salts, ox bile, sodium citrate
10. Black colour in oxidase, acid slant in TSI, red layer at top of SIM, negative citrate
11. E coli, Klebsiella, Proteus, Salmonella
12. Bacillus, Staphylococcus, Neisseria, E coli, Klebsiella
13. Pseudomonas, E coli, Alcaligenes, Streptococcus
14. 40%KOH, alpha naphthol, MRVP, p dimethylaminobenzaldehyde, methyl red reagent
15. Pink urease, low electrolytes, PAD pos, alkaline slant

MEDIA Tuts

Explain the relationship between:
Methyl red reagent; MRVP; acidic end products; pH6; Enterobacter aerogenes
Voges Proskauer; MRVP; non acidic end products; pH4; Escherichia coli

YOU NEED TO KNOW:
MRVP is the medium. It comprises 2 tests, MR and VP.
Both tests are used to differentiate between E coli and Enterobacter aerogenes.
Both orgs degrade glucose and form by products (E coli at pH4, and Ent at pH6)
Mr tests for pH4 and VP tests for pH6. In both tests a red colour is positive.
E coli end products are called acidic
Ent end products are called non acidic.
Therefore E coli is MR pos and VP neg
Enterobacter is MR neg and VP pos

CLED agar contd....

This is medium for the differentiation of urinary organisms. Its basic colour differs according to the manufacturer. Previously we had pale pink plates; now they are the prettiest green I've seen in a long time. Almost translucent green, like the sea on a clear summer day.

From the name, it contains cysteine, lactose and is electrolyte deficient. The electrolyte deficiency prevents swarming of .......?
LF are yellow
NLF are blue
but in addition to that.......
Pseudomanas is green with a rough colony edge
Staphylococcus aureus and Enterococcus faecalis are yellow (other Staphylococcus can be white)

A likely story......

the following relates to the orgs we have/are studying this semester.

Mr Brown is sick. He goes to the doctor who takes a specimen. Culture reveals an org that is citrate neg, urease neg, and does not produce hydrogen sulphide. It is a Gram negative bacillus.
What reaction would it give on Mac and CLED?
Why would it not grow on MSA?
If you inoculated a TSI and SIM, would it be incorrect to say that the org is non motile, indole pos and produces an alkaline slant? Why. (explain fully)
Name the organism.

identification of Staphylococcus and Streptococcus

these orgs are Gram positive cocci. Strept occur either in chains or as diplococci. Staph occur in grape like clusters.

to differentiate between Staph and Strept
catalase test (3% H2O2)
Staph is pos (immediate bubbling when org is added)
Strept is neg (no immediate bubbling when org is added)

to differentiate between S aureus and S epidermidis
DNAse test (stab inoculation)
S aureus is pos (clear zone around colonies after 1N HCl is added)
S epidermidis is neg (medium turns opaque around colonies after 1N HCl is added)