# 20.3: Procedures and Results

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## 1. Patient’s history and predisposing factors

Read the case study. Explain how any relevant parts of the patient’s history contributed to your final diagnosis as to the type of infectious disease seen here. The patient's history refers to anything given in the case study prior to that patient seeking medical attention for the current medical condition. You are urged to use the computers in lab to search reliable medically oriented Internet sources to support this. Reliable sources you might consider are Medscape (http://emedicine.medscape.com/infectious_diseases) and The Centers for Disease Control and Prevention (CDC) at http://www.cdc.gov/. Cite any sources you use at the end of this Patient's History section in APA style (https://www.scribbr.com/apa-examples/website/).

The patient's history should suggest a general type of infectious disease that is present, such as a urinary tract infection, a wound infection, gastroenteritis, pharyngitis, pneumonia, septicemia, etc. Do not look up the bacterium you eventually identify as the cause of this infectious disease. You do not know the causative bacterium at this point. You need to determine the general type of infection in order to determine what microbiological tests to perform to identify the bacterium causing the infection. Search at least one medically oriented reference article from a reliable site such as Medscape and use this article to support your diagnosis of the type of infectious disease seen here. Don't forget to cite any sources you used in APA style directly under this Patient's History and Patient's Symptoms sections of this Lab Report.

## 2. Patient’s signs and symptoms

Read the case study. Explain how the patient’s signs and symptoms contributed to your final diagnosis as to the type of infectious disease seen here. Signs refer to anything being measured by a medical professional during a physical exam such as blood pressure, respiration rate, heart rate, oxygen saturation, and temperature. Symptoms refer to symptoms being reported by the patient. You are urged to use the computers in lab to search reliable medically oriented Internet sources to support this. Reliable sources you might consider are Medscape (http://emedicine.medscape.com/infectious_diseases) and The Centers for Disease Control and Prevention (CDC) at http://www.cdc.gov/. Cite any sources you use at the end of this Patient's Symptoms section in APA style (https://www.scribbr.com/apa-examples/website/). Also see appendix F (SIRS and Sepsis) in your lab manual for an indication of whether or not the patient has SIRS.

The patient's signs and symptoms should suggest a general type of infectious disease that is present, such as a urinary tract infection, a wound infection, gastroenteritis, pharyngitis, pneumonia, septicemia, etc. Do not look up the bacterium you eventually identify as the cause of this infectious disease. You do not know the causative bacterium at this point. You need to determine the general type of infection in order to determine what microbiological tests to perform to identify the bacterium causing the infection. Search at least one medically oriented reference article from a reliable site such as Medscape and use this article to support your diagnosis of the type of infectious disease seen here. Don't forget to cite any sources you used in APA style directly under this Patient's History and Patient's Symptoms sections of this Lab Report.t.

## 3. Vocabulary list for medical terms used in the case study under signs and symptoms

List and define any medical terms used in your case study that describe the patients’s signs and symptoms that the average person not in the medical profession might not know.

## 4. Results of laboratory test given in the case study

List each lab test given in the case study that are done in a lab, such as total white blood count, differential white blood cell count, urinalysis, and X-ray, and explain how the results of that test helps to contribute to your diagnosis. Refer to appendix C (Complete Blood Count) and appendix D (Urinalysis) in your lab manual.

## 5. Gram stain

Give the Gram reaction (Gram-positive or Gram-negative and how you reached this conclusion) and the shape and arrangement of the unknown you were given. Remember that Staphylococci and Enterococci can look similar in a Gram stain when using a plate culture. If the result of the arrangement is inconclusive after seeing Gram-positive cocci, try doing the catalase test described in Lab 8 and state specifically how the results of the catalase test helped to confirm the arrangement. The catalase test will help you differentiate an Enterococcus from a Staphylococcus.

State how this contributed to your choice of microbiological tests and/or media to use next and why. The Gram stain is discussed in Lab 6.

Make sure you check your Gram stain results with your instructor before determining which microbiological lab tests you will perform.

## 6. Based on the results of your Gram stain, determine which of the following isolation media you will inoculate and why. Refer back to Labs 12, 14, and 15 to help determine your selection.

a. MacConkey agar (Lab 12)
b. Blood agar with NB disc (Lab 15)
c. Bile Esculin Azide agar (Lab 14)

Also inoculate a tube of Trypticase soy broth (TSB) with your unknown to be used next time for antibiotic susceptibility testing.

Inoculate each medium you chose, making sure to streak all petri plates for isolation. Incubate the plates upside down and stacked in the petri plate holder on the shelf of the 37°C incubator corresponding to your lab section. Incubate the TSB and Bile esculin agar tube (if used) in your test tube rack on the shelf of the 37°C incubator corresponding to your lab section.

Isolation Results

Explain why you chose to use or not use each of the isolation media.

a. Maconkey agar (Lab 12)

##### Videos

Why did you choose to use or not use this medium?

If you used this medium, describe the results of the MacConkey agar plate you inoculated with the sample from the patient. State specifically how this contributed to your decision as to what bacterium is causing the infection .

b. Blood agar with NB disc. (Lab 15)

Why did you choose to use or not use this medium and disc?

If you used this medium, describe the results of the Blood agar plate you inoculated with the sample from the patient. State specifically how this contributed to your decision as to what bacterium is causing the infection .

c. Bile Esculin Azide agar (Lab 14)

##### Videos

Why did you choose to use or not use this medium?

If you used this medium, describe the results of the Bile Esculin Azideagar you inoculated with the sample from the patient. State specifically how this contributed to your decision as to what bacterium is causing the infection .

## 7. Based on the results of your isolation media used in step 5 above, determine which of the following media you will inoculate or tests you will perform and why. Refer back to Labs 12, 14, and 15 to help determine your selection of media/tests and how to correctly perform the lab procedures.

a. Oxidase Test (Lab 12)
b. Cetrimide agar (Lab 12)
c. EnteroPluri-Test (Lab 12)
d. Mannitol Salt agar (Lab 15)
e. Coagulase test (Lab 15)
f. Bauer-Kirby antibiotic susceptibility testing on Mueller-Hinton agar (Lab 18)

Incubate the plates upside down and stacked in the petri plate holder on the shelf of the 37°C incubator corresponding to your lab section. Incubate the tubes in your test tube rack on the shelf of the 37°C incubator corresponding to your lab section.

Results of Additional Lab Media or Lab Tests Performed

Explain why you chose to use or not use each of the following tests or media.

a. Oxidase test (Lab 12)

##### Videos

Why did you choose to use or not use this test?

If you used this test, describe the results of the oxidase test and state specifically how this contributed to your decision of media to use.

b. Cetrimide agar (Lab 12)

##### Videos

Why did you choose to use or not use this medium?

If you used this medium, describe the results of the Cetrimide agar and state specifically how this contributed to your decision as to what bacterium is causing the infection .

c. EnteroPluri-Test (Lab 12)

Why did you choose to use or not use this test?

Using your Enterotube®II, identify the unknown you were given.

1. In the table below, put a (+) or a (-) in the Result row for each test.
2. Add up the value of each positive test in a group and put that number in the code for each group.
3. The 5 digit number is the CODICE number. Look that number up in the Codebook and identify your unknown.

Group 1

Group 2

Group 3

Group 4

Group 5

Test

Glucose

Gas

Lysine

Ornithine

H2S

Indole

Lactose

Arabinose

Sorbitol

VP

Dulcitol

PA

Urea

Citrate

Value

4

2

1

4

2

1

4

2

1

4

2

1

4

2

1

Result

Code

CODICE NUMBER:

Genus and species from the EnteroPluri-Test: _____________________________________

d. Mannitol Salt agar (Lab 15)

##### Videos

Why did you choose to use or not use this medium?

If you used this medium, describe the results of the Mannitol Salt agar plate you inoculated with the sample from the patient. State specifically how this contributed to your decision as to what bacterium is causing the infection .

e. Coagulase test (Lab 15)

##### Videos

Why did you choose to use or not use this test?

If you used this test, describe the results of Coagulase test and state specifically how this contributed to your decision as to what bacterium is causing the infection .

f. Bauer-Kirby antibiotic susceptibility testing on Mueller-Hinton agar (Lab 18)

##### Videos
Gram-Positive Unknown
Disc code Antimicrobial agent Zone in mm R I MS S
AMC-30 amoxicillin/
clavulanic acid
CTX-30 cefotaxime
FOX-30 cefoxitin
CIP-5 ciprofloxacin
DA-2 clindamycin
E-15 erythromycin
K-30 kanamycin
OX-1 oxacillin
SXT-25 sulfamethoxazole
+ trimethoprim
TE-30 tetracycline
TZP-110 piperacillin/tazobactum
VA-30 vancomycin

R = Resistant
I = Intermediate
MS = Moderately Susceptible
S = Susceptible

Gram-Negative Unknown
disc code antimicrobial agent zone in mm R I MS S
AK-30 amikacin
AMC-30 amoxicillin/
clavulanic acid
AMP-10 ampicillin
MEZ-75 mezlocillin
CTX-30 cefotaxime
FOX-30 cefoxitin
CIP-5 ciprofloxacin
CN-10 gentamicin
K-30 kanamycin
SXT-25 sulfamethoxazole
+ trimethoprim
TE-30 tetracycline
TZP-110 piperacillin/tazobactum

R = Resistant
I = Intermediate
MS = Moderately Susceptible
S = Susceptible

## Final diagnosis:

What infectious disease does the patient have?

What is the name of the bacterium causing this infectious disease?

Based on your Bauer-Kirby results, what antibiotics might be effective against this bacterium?