Cultures: Respiratory, Eye, Urine, Stool

Question 1

What are 3 lower respiratory tract specimens?

Answer 1

1) Sputum: Contaminated with normal upper-respiratory tract normal flora.
2) Tracheal Aspirate- Suctioned from endotracheal tube or tracheostomy
3) Bronchial Alveolar Lavage- Bronchial brushings and washings- Upper resp. contamination minimized

Question 2

How would you collect a sputum specimen:

Answer 2

1) Rinse mouth with water
2) Take deep breaths, and then cough forcefully into specimen container.
3) Examine specimen to contain at least 1 ml of thick mucus. Early morning preferred
4) Send specimen at ambient temperature, refrigerate for delay >1 hr

Question 3

> 25 epithelial cells/LPF in sputum stain means what?

Answer 3

Oral contamination- request new specimen

Question 4

Bacterial etiologic agents of eye infections

Answer 4

1) H. Influenzae
2) Staph aureus
3) Strep pneumo
4)Pseudomonas aeruginosa
5) Bacillus cereus
Newborn: N. gonorrhoeae, Chlamydia trachomatis

Question 5

Purulent conjunctivitis eye specimen collection

Answer 5

Collect purulent material with culturette, place swab into sleeve with transport media and transport at ambient temperature or 2-8 degrees C for viral cultures

Question 6

Corneal infections eye specimen collection

Answer 6

Swab conjunctiva, collect multiple corneal scrapings and inoculate directly onto bacterial agar media

Question 7

Urinalysis: Catheterized urine- Nitrite=negative. This specimen result rules out a urinary tract infection?

Answer 7

NO- Enterococcus may not have a positive nitrite

Question 8

True/False: Catheterized urine is considered sterile?

Answer 8

False: Catheter can introduce bacteria into the bladder as it passes through urethra

Question 9

T/F: Most labs do gram stains on urine:

Answer 9

False- If urinalysis indicates UTI, gram stain warranted.

Question 10

Most laboratories will setup what 2 types of culture media

Answer 10

Sheep Blood Agar, and MacConkey agar

Question 11

T/F: 60-80% of urine cultures received in the lab will be “No growth” or “growth of contaminants only”

Answer 11

True

Question 12

T/F: >100,000 cfu/ml is indicative of a UTI, except when the isolate is contaminant

Answer 12

True

Question 13

T/F: 10,000-100,000 cfu/ml does not indicate an infection, especially if only one colony type is growing

Answer 13

False- it may indicate infection

Question 14

T/F: If there is growth of three or more different organisms, work-ups are ordered

Answer 14

False: consider the specimen contaminated and work-ups are not done

Question 15

Clean catch urine reported as: 10,000 CFU/ml Staphylococcus sp. coag negative, >100,000 CFU/ml diphtheroids, 50,000 CFU/ml lactose-fermenting gram-negative rods.

This culture is interpreted as:

Answer 15

Contaminated

Question 16

A suprapubic urine culture interim report: 500 CFU/ml non-lactose fermenting GNR oxidase negative. These results are interpreted as:
A) Colony count too low
B) Colony count significant but organism is not known to cause UTI
C) Colony count significant, organism significant

Answer 16

C) Colony count significant, organism significant

Question 17

T/F: A urinalysis result on a voided urine specimen included: many bacteria seen on the microscopic exam. Based on this result, this urine should be cultured due to possible UTI.

Answer 17

False: This is a voided urine and not collected properly

Question 18

T/F: If a patient is in the hospital for >3 days and develops diarrhea, a stool culture should be performed.

Answer 18

False- Diarrhea usually due to antibiotic therapy, altered diet

Question 19

Routine stool culture for enteric pathogens usually include what 3 organisms?

Answer 19

Salmonella, Shigella, and Campylobacter

Question 20

Results of direct specimen biochemical tests performed as part of a routine urinalysis exam that are consistent with UTI are:

Answer 20

Nitrite positive, leukocyte esterase positive

Question 21

The interim report of a clean-catch urine culture is:
>100,000 CFU/ml Enterococcus sp.
This is consistent with:

Answer 21

A UTI

Question 22

The leading cause of death in the US related to seafood consumption is:

Answer 22

Vibrio vulnificus

Question 23

Bacterial diarrhea associated with seafood is caused by:

Answer 23

Vibrio parahaemolyticus

Question 24

An organism that effects all age groups that can be asymptomatic or lead to severe inflammatory diarrhea that is associated with incorrect food handling practices, consumption of poorly cooked poultry, and raw milk is:

Answer 24

Campylobacter

Question 25

MacConkey Agar selects for what type of pathogens?

Answer 25

Enterobacteriaceae and other GNRs

Question 26

MacConkey Agar differentiates for what type of pathogens?

Answer 26

Lactose and non-lactose fermenters: Normal enteric flora will ferment lactose (pink colonies). Salmonella and Shigella will not ferment lactose (colorless or transparent colonies).

Question 27

In Hektoen Enteric Agar, Salmonella and Shigella will produce produce what color colonies?

Answer 27

Green to blue-green colonies. Non pathogens will ferment one or both carbohydrates (H2S, Lactose and sucrose) to appear bright orange or salmon pink

Question 28

A Gram stain is performed on stool to detect:

Answer 28

white blood cells

Question 29

How would you isolate campylobacter species?

Answer 29

Blood agar campy-BAP- Brucella agar is base. Antibiotic mixture (vanco to inhibit gram positives), campylobacter species are flat, gray, non-hemolytic colonies.

Question 30

What agr is used to normally isolate E. coli 0157:H7?

Answer 30

MacConkey Sorbital Agar- appears colorless while others appear pink to red in color

Question 31

Non-Lactose fermenting GNR H2S+: Suspicious colonies for which organism?

Answer 31

Salmonella

Question 32

Non-Lactose fermenting GNR: Suspicious colonies for which organism?

Answer 32

Salmonella or Shigella

Question 33

If stool culture negative at 72 hours, it is reported as:

Answer 33

No salmonella, Shigella or Campylobacter isolated