Proper specimen collection is important for diagnosing infectious diseases. Different specimens like blood, urine, stool, sputum, wounds, and throat can be collected and tested. Each type of specimen has specific collection guidelines to obtain the most accurate results and avoid contamination, such as using aseptic technique for blood cultures and collecting clean-catch midstream urine samples.

2.  Proper collection of specimens is important to
maximize the outcome of laboratory tests for
the diagnosis of infectious diseases
 A variety of laboratory tests can be performed
to make a presumptive or definitive diagnosis
so that therapy can begin.

3. TYPES OF SPECIMEN
COLLECTION

4. Blood Culture
 Normally a sterile body fluid.
 Specimens obtained by venipuncture are
preferred over sampling from vascular
catheters unless testing for a central line
infection.
 Timing is determined by the patient's clinical
condition and should be indicated by the
ordering clinician.

5.  Usually collection is spaced over 24 hours.
 Aseptic technique is essential to avoid
contaminating the specimen with organisms
colonizing the skin.
 Cleanse the venipuncture site with 2%
chlorhexidine gluconate or povidone-iodine
and allow to dry. In case of allergy, use 70%
alcohol.

6.  The diaphragm tops of the culture bottles are
not sterile and must be wiped with alcohol
before injection of blood.

7. Urine Culture
 Normally a sterile body fluid.
 A clean-catch midstream urine collection
provides the best method for obtaining a
specimen to detect a UTI
 Patients who are catheterized should have the
specimen withdrawn using a sterile syringe
from the catheter sampling port

8.  Urine specimens must be transported to the
laboratory promptly. If not cultured within 30
mins of collection, urine must be refrigerated and
cultured within 24 hrs.
 Clean-catch midstream urine specimens that have
more than 100,000 colonies of bacteria per mL of
urine may be indicative of infection.
 Other types of urine specimens may be collected,
such as a straight in-and-out catheter specimen or
suprapubic bladder drainage

9. Stool Culture
 Obtained to culture organisms that are not part
of the normal bowel flora
(eg, salmonella, shigella, rotavirus)
 Patient should defecate into a sterilized
container or bedpan. Stool specimens should not
contain urine or water from the toilet bowl.
 Stool specimens can also be obtained directly
from the rectum using a sterile swab.

10. Sputum Culture
 Specimen needs to be from the lower
respiratory tract, not oropharyngeal secretions.
 The laboratory will perform a Gram stain on all
sputum specimens to determine if they are
representative of pulmonary secretions.
 A specimen containing a majority of cells from
squamous epithelium will be rejected.

11.  The most common method of collection is
expectoration from a cooperative patient with a
productive cough
 Early morning is the optimal time to collect
sputum specimens.
 A sputum specimen can be collected in a
sputum trap from patients who have artificial
airways and require suctioning.

12.  If a patient cannot produce sputum, sputum
induction using an aerosol nebulizer may assist
with loosening thickened secretions.
 Bronchoscopy may be required to obtain
sputum if induction fails.

13. Wound Culture
 Specimens are cultured for aerobic and
anaerobic organisms.
 Using a sterile swab supplied by the
laboratory, collect as much exudate as possible
from the advancing margin of the lesion

14.  Avoid swabbing surrounding skin.
 Place the swab immediately in appropriate
transport culture tube and take to the
laboratory.
 Label with the specific anatomic site.

15. Throat Culture
 Use a tongue depressor to hold the tongue
down.
 Carefully yet firmly rub swab over areas of
exudate or over the tonsils and posterior
pharynx, avoiding the cheeks, teeth, and gums.
 Insert swab into packet and follow directions
for handling the transport medium.