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COLLECTION OF RESPIRATORY TRACT SAMPLES

Preferably specimens should be taken within the first 3 days after onset of symptoms for most respiratory infections

Specimens are collected from the upper or lower respiratory tract, depending on the site of infection. Upper respiratory tract pathogens (viral and bacterial) are found in throat nasopharyngeal specimens. Lower respiratory tract pathogens are found in sputum specimens. For organisms such as Legionella, culture is difficult, and diagnosis is best based on the detection of antigen excreted in the urine.

When acute epiglottitis is suspected, no attempt should be made to take throat or pharyngeal specimens since these procedures may precipitate respiratory obstruction. Epiglottitis is generally confirmed by lateral neck x-ray, but the etiological agent may be isolated on blood culture.



MATERIALS

SUPPLIES REAGENTS

Dacron and cotton swabs

Tongue depressor

Flexible wire calcium alginate tipped swab (for suspected pertussis)

Nasal speculum (for suspected pertussis) – not essential

Suction apparatus or 20-50ml syringe.

Sterile screw-cap tubes, and wide mouthed clean sterile jars (minimum volume 25 ml)

Transport media – bacterial and viral



UPPER RESPIRATORY TRACT SPECIMENS


B.1.1  THROAT SWAB


PROCEDURE

STEP ACTION
1

Hold the tongue down with the depressor.

Use a strong light source to locate areas of inflammation and exudate in the posterior pharynx and the tonsillar region of the throat behind the uvula

2

Rub the area back and forth with a Dacron or calcium alginate swab.

Withdraw the swab without touching cheeks, teeth or gums and insert into a screw-cap vial containing viral or bacterial transport medium.

3

Break off the top part of the stick without touching the tube and tighten the screw cap firmly

4

Label the specimen containers

5

Complete the laboratory request form.



B.1.2  PRE-NASAL AND POST NASAL SWAB


PROCEDURE

STEP ACTION
1

Seat the patient comfortably, tilt the head back and insert the nasal speculum

2

Insert a flexible swab beneath the inferior turbinate of either nostril or leave in place for a few seconds and move the swab upwards into the nasopharyngeal space.

3

Rotate the swab on the nasopharyngeal membrane a few times; slowly withdraw with a rotating motion against the mucosal surface of the nostril.

4

Remove the swab carefully and insert it into a screw-cap tube containing transport medium.

5

Repeat the procedure in the other nostril using a new sterile swab

6

Label the vial with patient’s name type of specimen and date of collection



B.1.3  ASPIRATES


PROCEDURE

STEP ACTION
1

Nasopharyngeal secretions are aspirated through a catheter connected to a mucus trap and fitted to a vacuum source.

2

The nasal aspirates are collected by introducing a few ml of saline into the nose with a syringe fitted with a fine tubing or catheter.

3

The catheter is inserted into a nostril parallel to the palate.


The vacuum is then applied and the catheter is slowly withdrawn with a rotation motion.

4

Mucus from the other nostril is collected with the same catheter in a similar manner.

5

After mucus has been collected from both nostrils, the catheter is flushed into a screw cap vial with 3 ml viral transport media

6

Label the vial with patient’s name type of specimen and date of collection




LOWER RESPIRATORY TRACT SPECIMENS


B.2.0  SPUTUM


PROCEDURE

STEP ACTION
1

Instruct patient to take a deep breath and cough up sputum directly into a wide mouth sterile container.

Avoid saliva or postnasal discharge.

Minimum volume should be about 1 ml

2

Label the specimen containers

3

Complete the laboratory request forms



HANDLING AND TRANSPORT

  • All respiratory specimens except sputum are transported in appropriate bacterial/viral media

  • Transport as quickly as possible to the laboratory to reduce overgrowth by commensal oral flora.

  • For transit periods up to 24 hours, transport bacterial specimens at ambient temperature and viruses at 4-8oC in appropriate media.

Caribbean Public Health Agency © 2014