Infection Control Manual

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Notes on Specimen Types

Swabs general:
From dry areas moisten swab with sterile transport medium. Rotate swab. No dabbing. Do not break swabs unless designed for this purpose.

 

Nose swabs:
If purulent discharge the area at the back of the nose should be sampled. For carriers, (MRSA screening), the moistened swab should be directed away from the turbinates just within the anterior nares. The swab should be rotated five times (clockwise for R and counter-clockwise for L nostril) to obtain sufficient material. A single swab may be used for both nostrils.

 

Throat swabs:
Avoid mouth and tongue. Sample any lesion, exudate, areas of inflammation.

 

Ear swabs:
Fine wire swab is required under direct vision, a normal swab will only sample the external ear.

 

Eye swabs:
Transport swabs should not be used, (lysozyme present). Direct culture onto culture medium preferred. Discuss with Medical Laboratory Scientists. Chlamydia/trachoma: Special swabs required.

 

 

Genital tract:

To take an HVS or Cervical swab, a speculum must be used, as faecal contamination must be avoided. Transport medium is essential. Charcoal transport medium for gonorrhoea. The laboratory should be specifically requested to rule out gonorrhoea, Chlamydia, or herpes. Special swabs are required for the latter two. Best to do a cervical swab as these organisms not reliably obtained from HVS. HVS only useful for Candida, Trichomonas and Mycoplasma hominis.

 

Wound swabs:
Pus preferred. Take swab before cleaning local area. Take from affected site, NOT surrounding tissue. The swab should be rotated gently to collect as much pus or exudate as possible. Transfer without delay into transport medium. Anaerobic bacteria may die in minutes. Preferably send 1-2 ml of pus in a sterile container (Universal or plain vacutainer) dispatch to laboratory without delay.

 

Sputum:

Send sputum, not saliva. Early morning specimens preferred as this is the most productive time. Quality not quantity. 2 ml is ample. Physiotherapy may be required. Avoid mouth contamination. (A mouth full of bacteria that may confuse culture interpretation). In the case of pneumonia the laboratory will report significant numbers. Delay in transport to the laboratory may increase the number of bacteria present and reduce the numbers of some relevant pathogens.

 

Urine:

Wash genital area with soap and water and dry thorooughly. (Some studies have shown that this is not necessary provided the urine is collected using good technique and processed immediately). The use of antiseptic may contaminate the specimen and confound the findings. Male: Retract foreskin. Female: Outer and inner labia cleaned in a front to back direction. (Reduces perineal contamination). Patient micturates with labia separated. The urine collected from the middle portion of the urine stream (MSU) is least contaminated. Container should be 4/5 full. This gives the laboratory ample urine for testing and allows the MLSO to remove the lid without spillage. If the container has a paper funnel, please remove it completely before putting lid on container, pushing the funnel into the container makes testing virtually impossible, and also makes the urine leak in transit.

 

Catheter specimens of urine:

NOT from bag (Contains stagnant, almost certainly contaminated, urine). NOT from catheter drainage bag junction (High risk of contaminating system). Collect from self sealing sleeve of the drainage tubing using a fine bore needle and syringe (take care and do not place a finger behind the catheter!). Urinary catheter tips are inappropriate specimens and will not be processed. Urine samples should be transported to the laboratory within one hour of collection or held at 4°C and then transported to the laboratory without delay.

 

Faeces:

May be examined for enteropathogenic bacteria, viruses, ova, cysts, parasites and toxins. May be collected into bedpan, or clean plastic bag draped over toilet (do not flush the plastic down the toilet). 5-10 ml of faeces is ample; over filled containers have been known to explode on warm days. Take sample with a spatula or "tongue depressor" from mucoid and blood stained areas if present. If normally formed, samples from middle and both ends of the formed stool are very important for ova, cysts and parasites. "Hot" stools not necessary, but all stool samples should be reasonably fresh, and very fresh to see amoebic trophozoites. Solid faeces will not be processed unless justified (eg looking for continuing carriage of Salmonella sp.)