Microbiology lab practical 3

Bacteria commonly causing urinary tract infections are:

1) members of the family, enterobacteriaceae, used in this excersie. 2) pseudomonas aeruginosa 3) staphylococcus aureus

The enterotube is a manual procedure that uses _________________ and ___________ to detect changes due to metabolic activity. The tube simultaneously tests for 15 biochemical reactions.

12 media, color indicators

Definition: antigen:

A molecule (I.e. Protein or sugar) that triggers and immune response (I.e. Protein a in staph aureus, antigen a in strep pyrogens.)

Definition: antibody

A protein molecule secreted by b plasma cells which bind to specific antigens.

Why does the doctor need a list of several antibiotics to choose from?

Allergies, alternatives to resistance, patient history

Each Utis bacteria must not only be identified, but the tested for _____________, because the bacteria causing one infection may have different resistance genes than the same kind of bacteria causing the next infection. This is BECAUSE of ___________ picked up from other bacteria.

Antibiotic sensitivity, plasmids

In real-life, ___________________ are used to identify bacteria.

Automated analyzers

You will know the _________, and the disks will tell you the ___________ you are looking at. You need both pieces of information to use the table in lab manual.

Bacteria, antibiotic

__________ are antibiotics that work against several types of bacteria. Can kill normal flora.

Broadspectrum

Step 1 urine culture

Collect clean catch, catheter, or bag

Group b: strep agalactiae-

Commonly colonies the vagina, and can be passed on to newborns. #semmelweiss. OBGYNS test for this in 3rd trimester pregnant women and treat to prevent meningitis in newborn.

When possible infections should be _______ and tested for _________ _________.

Cultured, antibiotic sensitivity

Step 7 urine culture

Determine antibiotic sensitivity, to be sure the medication will cure the infection

The Kirby bauer method is a _________________, the same as antiseptic lab.

Disc diffusion

We will be using bacteria from the family ____________________. These bacteria are _________________ and often found in the intestines. These are commonly sources of Utis due to proximity of the urethra ________.

Enterobacteriaceae, gram negative, portal of exit

Hospital acquired mrsa

Found internally, after a surgery

Community acquired mrsa:

Found on the skin, such as a boil.

Non-grouped (no reactive antigens membrane): strep pneumonia-

Frequent cause of bacterial pneumonia with high death rate in elderly. Confirmed by p disc (optichin) sensitivity.

General characteristics of staphylococci

Gram positive, cocci Progenitor (puss forming) Form clusters of cells, like grapes

Step 3 urine culture

Gram stain. This tells you which antibiotics may be good choices to start. Also tells you the shape of the bacteria.

Step 6 urine culture

Identification (enterotube), to know which is the problem organism.

The big picture for enterotube identification:

Inoculate, incubate, read color reactions --> 5 digit code, look up in book

Staphylococcus epidermidis is a normal flora on the skin. It is pathogenic when it is _______ the body.

Inside

Step 5 urine culture

Isolate pathogen, pure culture, because bacteria exsist in mixed populations.

Staphylococcus aureus with resistance genes is ______________. Methicillin-resistant staphylococcus aureus. Resistant to all the -Illins.

MRSA

The agar we will use, for the Kirby bauer test, is the _______________. The oatmeal base does not interfere with antibiotics (chemically).

Mueller Hinton ii

Utis ______________ addressed because bacteria in the kidneys can lead to life-threatening blood infections.

Must be

_________ kill specific bacteria.

Narrow spectrum

Step 4 urine culture

Perform colony count and determine if an infection is present. An infection is greater than or equal to 100,000 crus/mls

The staphyloslide test is a test for the presence of _______. It is a _______________.

Protein a - antigen, serological test

Step 2 urine culture

Refrigerate it or plate it because after 2 hours at room temperature the lab rejects the urine. In 2 hours, bacteria can reproduce several times, leading to a false positive. For example, the generation time for E. coli. Is about 40 minutes.

What is the enterotube looking for?

Sugars, amino acids, enzyme activity, and gas production.

Definition: intermediate:

The bacteria has some resistance, and this antibiotics is not the best choice.

Definition: resistance:

The bacteria is resistant, and this antibiotic will not cure the infection.

Definitions: sensitive:

The bacteria is sensitive to the antibiotic.

Definition: agglutination test:

The clumping of bacterial cells in the presence of an antibody.

Group D enterococcus: enterococcus faecalis, enterococcus faecium-

They carry antibioic resistance genes and pass plasmids around.

Staphylococcus saphrophyticus can cause ___________.

Utis

Group a: strep pyogenes-

Which is responsible for 25% of upper respiratory infections. Other s. Pyogenes strains cause "flesh-eating strep". This has antigen a.