The purpose of this guideline is to provide guidance about specimen collection at Great Ormond Street Hospital.
Table of contents
Microbiological and virological laboratory testing has a key role in the management of children with infection. Accurate and rapid identification of significant micro-organisms is vital for guiding optimal anti-microbial therapy, and improving outcome from infectious disease.
Laboratory diagnosis is also essential for effective infection control in both the hospital and community settings, as well as providing invaluable epidemiological data.
Clinicians (including nurses, doctors and professionals allied to medicine) have responsibility for the collection and safe transportation of samples to the laboratory. The validity of test results largely depends on good practice in the “pre-test” stage and it is essential that documentation is accurate and comprehensive (Higgins 1994).
Microbiological tests are not as standardised as some other lab tests; the way in which a sample is processed and the results are interpreted depend heavily on the information provided with the specimen.
Contamination of samples, especially those from normally sterile sites such as blood or cerebrospinal fluid, leads to misleading results, inappropriate antibiotic usage and unnecessary laboratory work.
Prolonged periods of storage at ambient temperature and delay in transport of specimens to the laboratory may increase the number of contaminants present.
It is therefore essential that every effort should be made to avoid these problems.
Note: While this guideline refers to the ‘child’ throughout, all activities are applicable to young people.
Specimen collection is undertaken when laboratory investigation is required for the examination of material, eg tissue, body fluid or faeces to aid diagnosis.
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Laboratory request forms are printed from the Patient Information Management System (PIMS). Use the labels on the form to label the specimen accompanying the form. These are bar coded to aid the audit trail.
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All specimens must be clearly labelled to identify their source.
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DO NOT pre-label specimen containers as this increases the risk of errors. The specimen must be labelled next to the child/patient when the sample is taken.
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A laboratory request form with the following information must accompany the specimen. This aids interpretation of results and reduces the risk of errors.
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Patient's name, DOB, ward/department and hospital number
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Type of specimen and the site from which it was obtained
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Date and time collected
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Diagnosis with history and reasons for request such as returning from abroad (specify country) with diarrhoea and vomiting, rash, pyrexia, catheters in situ or invasive devices used, or surgical details regarding post operative wound infection
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The question that needs an answer by having the sample tested
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Any antimicrobial drug(s) given
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Consultant's name
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Name/bleep number of the clinician who ordered the investigation, as it maybe necessary to telephone preliminary results and discuss treatment before the final result is authorised
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Always explain the procedure to the child and parent and the reasons for taking the specimen. Separate permission must be obtained from the child and parent if specimens are sought for research purposes. They have a right to refuse without any obligation (Ethics Advisory Committee 1992).
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Hands should be washed before and after specimen collection. In standard precautions, gloves should be worn when collecting or handling specimens.
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When collecting certain specimens, eg catheter urines and cerebro-spinal fluid, every effort should be made to avoid infecting the child. An appropriate aseptic or aseptic non-touch technique should be used.
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All pathological specimens must be treated as potentially infectious and local written laboratory protocols should be followed for the safe handling and transportation of specimens (Health Services Advisory Committee 1986). Specimens should be collected in sterile containers with close fitting lids to avoid contamination and spillage. All specimen containers must be transported in a double sided, self sealing polythene bag with one compartment containing the laboratory request form and the other the specimen.
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Ideally microbiological specimens should be collected before beginning any treatment such as antibiotics or using antiseptics. However, treatment must not be delayed in serious sepsis.
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When collecting pus specimens obtain as much material as possible as this increases the chance of isolating micro-organisms which maybe difficult to grow or are minimal in number eg tuberculosis. Pus should be sent in a sterile specimen container, not on a swab.
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Transport medium may be used to preserve micro-organisms during transportation. Charcoal medium improves the isolation of bacteria by neutralising toxic substances such as naturally occurring fatty acids found on the skin.
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As many viruses do not survive well outside the body special viral transport medium is used. This is obtained from the Virology Department, Level 4 Camila Botnar Laboratory (CBL). It may be stored at room temperature on ward, but should only be used for viral investigation. The viral transport medium must not be used after the expiry date.
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At GOSH specimens are delivered to the laboratories by porters, and more urgent specimens via the pneumatic tube delivery system.
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Specimens sent by post outside GOSH must be packed and sent by microbiology as they need to be sent according to UN regulations. The specimen must be wrapped in a plastic bag, encased in an absorbent material within another plastic bag, placed in an approved plastic container within an approved cardboard box with the appropriate addressed infectious diseases stickers. A warning “Pathological Sample” along with the sender’s name and address must be visible on the outside. Specimens should not be sent to a laboratory outside the Trust direct from a ward, but sent through the microbiology laboratory to ensure correct packing and audit trail.
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In children suspected of suffering from viral haemorrhagic fevers such as Lassa fever, Marburg or Ebola virus, the Infection Control Team must be consulted before any specimens are taken (Advisory Committee on Dangerous Pathogens 2004; Advisory Committee on Dangerous Pathogens 1998; Advisory Committee on Dangerous Pathogens 1996). GOSH has no containment Level 4 facilities in the laboratory.
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Chlorine releasing granules or a hypochlorite solution (10,000 parts per million of available chlorine) must be available for decontamination of any spillages. Care must be taken as chlorine releasing fumes have occurred when mixed with urine (Safety Action Bulletin 1990).
This will vary according to the specimen required but must include:
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disposable gloves (Expert Advisory Committee on AIDS 1990)
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additional personal protective equipment (apron/gown, mask/respirator, visor - where applicable)
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a protective tray
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a sterile container for the specimen
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appropriate transport medium, if required
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laboratory specimen form
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a polythene transportation bag
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biohazard label, if required
Blood sampling should be performed by a healthcare worker trained and competent in the procedure. As there are many haematological, biochemical, immunological and microbiological blood tests (Higgins 1995a; Higgins 1996; Higgins 1997; Higgins 1995b; Higgins 1995c) the person should seek information as to the appropriate laboratory containers required for specific tests and the amount of blood required.
This information is available on PIMS or in the individual departmental user manuals. Protective clothing such as gloves and aprons (and facial protection when appropriate) must be used along with the aseptic non-touch technique.
The “Broken Needle Technique” (breaking the hub of the needle to obtain blood from small infants) poses an additional risk of injury to the child and user and must NOT be used.
Detection of microorganisms by culture of blood is essential in the diagnosis of bloodstream infections, including infective endocarditis, infections presenting as pyrexia of unknown origin, prosthetic material infections and intravenous catheter infections. Blood culture may also detect bacteraemia associated with primary infections such as pneumonia and septic arthritis. Accurate positive results provide valuable information to guide optimal antibiotic therapy early on which can improve outcome from these conditions.
On the other hand, contaminated blood cultures can cause considerable diagnostic confusion and lead to unnecessary or sub-optimal antimicrobial therapy.
Contamination may be prevented by careful collection of the blood using the aseptic non-touch-technique (Higgins 1995a). If possible avoid palpating the vein after cleansing the skin. The specimen should also preferably be taken during pyrexial episodes as more bacteria may be present at that time.
Blood cultures should be taken when there is a clinical need to do so in response to any of the following clinical signs suggestive of sepsis and a deteriorating clinical picture including:
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abnormalities in
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heart rate
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core temperature
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leucocyte count
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presence of rigors or chills
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other focal signs of infection, such as pneumonia, septic arthritis, meningism, urinary tract infection including pyelonephritis and acute abdominal pathology.
Procedure (Department of Health (DH) 2007):
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Use both blood culture bottles and scrub the bung with a 2% chlorhexidine/70% alcohol wipe (eg Clinell®) for 15 seconds and allow to dry prior to inoculation.
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Soap and water should be used to clean any visibly soiled skin. The skin must then be decontaminated with a 2% chlorhexidine/70% alcohol applicator (eg Chloraprep® Sepp 0.67 ml) and allowed to dry. Do not re-palpate vein (even with gloved hand) after decontamination (Pratt 2007).
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After withdrawing the blood, insert the blood into the container with a new sterile needle. There is a risk of contamination of skin organisms on the needle used to withdraw the blood.
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Volume of blood is the most critical factor in the detection of blood stream infection. Place as much blood as possible (up to 4ml in the yellow aerobic bottle (priority) and up to 10 ml in the anaerobic orange bottle. For neonates 1-2 mls of blood is recommended (Kellogg et al 2000). However the sensitivity of neonatal blood cultures is increased if more blood is cultured.
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If inoculating more than one type of blood culture bottle, the anaerobic culture bottle should be inoculated first and then the aerobic culture bottle, so that oxygen trapped in the syringe will not be transferred to the anaerobic bottle.
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Inoculation of the blood into the blood culture bottles should be performed first before inserting blood into other bottles as many of these bottles are not sterile and accidental contamination may occur.
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Children with suspected line sepsis, blood for culture may be taken from a peripheral vein stab and also from the appropriate intravascular lines to enable identification of colonisation of the line. In cases of suspected bacterial endocarditis three blood cultures should be taken from separate venepunctures to optimise recovery of bacteria which may be present low in numbers.
The relationship between drug dose, drug concentration in biological fluid and the individual child’s metabolic process must be understood for interpreting results. The results may be affected by the route of administration, age of the child and disease process such as liver and renal disease. The analysis involves testing levels in blood serum or plasma in direct relationship to drug administration.
Routine in house drug level assay is available for amikacin, gentamicin, tobramycin and vancomycin. Other levels are referred and should be discussed.
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Individual antibiotic policies are on the Medicine and Pharmacy intranet web page and available upon request.
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Record on the laboratory form/sample the drug, dose and mode of administration, the time the drug is given and whether the sample is a “peak” or “trough” level.
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Trough levels are taken immediately prior to the time a drug is due; peak levels are taken one hour after bolus or infusion finished.
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Blood for antibiotic assay must not be taken through the same catheter which has been used to give the antibiotic at any time. Antibiotics bind to plastic and the drug may release intermittently giving false results.
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Spurious low or high level results may occur if blood is drawn from any central venous catheter and ideally levels should not be drawn from a central venous catheter.
Specimens such as skin, muscle, kidney, liver, jejunal, tissue or brain biopsies are generally obtained by medical staff either under general or local anaesthetic according to the site. A sterile technique is required for all these procedures. All biopsy specimens must be discussed with the relevant laboratory personnel in order that:
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The most appropriate specimen and laboratory tests are undertaken. If the specimen is small it may be necessary to limit the range of tests.
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Check if the specimen is to be fixed in formalin. DO NOT use formalin if the specimen is for microbiological investigation. In many cases both histopathological and microbiological/virological analysis will be required and it is critical that separate specimens be sent for these purposes so they are processed and transported appropriately.
Sampling of cerebrospinal fluid is essential for the accurate diagnosis of infective meningitis and may aid in the diagnosis of encephalitis.
Cerebro-spinal fluid (CSF) is most commonly obtained via a lumbar puncture performed by medical staff. A sterile technique is required as there is a risk of introducing infection itself causing meningitis. Specimens of CSF should be dispatched to the laboratory immediately.
Out-of-office hours it is essential that the on-call laboratory staff are contacted when the sample is being transported. It is important not to store the specimen in a refrigerator as this may cause the cells to deteriorate or lyse giving rise to misleading results.
It is common practice to send three separate collection tubes of CSF when investigating for evidence of sub-arachnoid haemorrhage, as the initial part of the sample may be contaminated with blood from outside the sub-arachnoid space.
If this is performed, it is important to label the tubes as such and specifically request counts on the first and third samples. It is also important to remember that a CSF glucose level (sent separately to chemical pathology) can only be accurately interpreted in conjunction with a simultaneous plasma glucose level.
No antibiotics or other therapeutic agents should have been in the aural region for about three hours prior to sampling the area as this may inhibit the growth of organisms.
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If there is purulent discharge this should be sampled.
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Place a sterile swab into the outer ear and gently rotate to collect the secretions.
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Place swab in transport medium.
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For deeper ear swabbing a speculum may be used. Experienced medical staff only should undertake this procedure as damage to the eardrum may occur.
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Where possible ask the child to look upwards and gently pull the lower lid down or gently part the eyelids.
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Use a sterile cotton wool swab and gently role the swab over the conjunctival sac inside the lower lid. Hold the swab parallel to the cornea to avoid injury if the child moves.
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Place the swab in the transport medium.
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For suspected Chlamydia trachomatis infection obtain a Chlamydia sampling swab from the virology department. These tests are referred to an external laboratory and are infrequently performed, therefore swabs may not be immediately available and testing may be delayed pending request for swabs.
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Clean the eye first with sterile normal saline to obtain a clear view of the conjunctiva.
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Using the swab, part the eyelids and gently rub the conjunctival sac of the lower lid to obtain epithelial cells.
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Place the swab in the transport medium provided.
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Identification will be by the current molecular test employed at the referral laboratory.
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Please specify whether the sample is a routine (admission) screening sample or an investigation for suspected intestinal infection.
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If viral gastroenteritis (eg Norovirus, Rotavirus) is suspected, the stool specimen should be sent to the virology laboratory. To exclude a bacterial cause a second stool specimen can be sent to the microbiology laboratory.
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A faecal specimen is more suitable than a rectal swab.
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A specimen can be obtained from a nappy or clean potty.
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Use the scoop attached to the inside of the lid of the specimen container to place faecal material into the container.
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Where diarrhoea is present, a small piece of non-absorbent material lining the nappy can be used to prevent material soaking into the nappy.
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Examine the sample for consistency, odour or blood and record observations to monitor changes.
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If segments of tapeworm are seen, send to the laboratory. Tapeworm segments can vary from the size of rice grains to a ribbon shape, one inch long.
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For the identification of Enterobius vermicularis (threadworm/pin worm) material should be obtained first thing in the morning on awakening by using a clear adhesive tape (Sellotape®) slide. Place the sticky side of a strip of tape over the anal region to obtain the material and stick the tape smoothly onto a glass slide. The worm can then be identified under the microscope. Thread worm lay their ova on the perianal skin at night and therefore will not be seen in a faecal specimen.
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Where acute amoebic dysentery is suspected, the specimen of stool must be freshly dispatched to the laboratory. The parasite causing amoebic dysentery exists in a free-living motile form and in the form of non-motile cysts. Both forms are characteristic in their fresh state but the motile form cannot be identified when dead. ‘Hot faeces’ should be discussed with the laboratory prior to collection.
Special containers (Dermapak®) may be obtained from the microbiology department:
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Samples of infected hair should be removed by plucking the hair with forceps or gloves. The root of the hair is infected not the shaft.
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Samples of the whole thickness of the nail or deep scrapings should be obtained.
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The skin should be cleaned with an alcohol swab. Epidermal scales scraped from the active edge of a lesion or the roof of any vesicle should be obtained.
Swallowed sputum containing Mycobacterium tuberculosis may be obtained through gastric washings. Children generally do not produce sufficient sputum, therefore gastric washings are obtained for laboratory analysis to aid diagnosis of pulmonary Mycobacterium tuberculosis.
The detection of alcohol acid fast bacilli (AAFB) is not adequate, alone, for diagnosis of Mycobacterium tuberculosis as other environmental AAFBs may be present. Culture of the organism is always performed and may take between 6-12 weeks to confirm diagnosis. Three consecutive early morning specimens should be obtained. There are usually only small numbers of organisms present so as much material as possible should be obtained. As AAFB are often found in tap water sterile water must be used.
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Fast the child for at least six hours overnight.
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Operators must take appropriate precautions, such as the use of PPE.
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Pass a naso-gastric tube.
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Aspirate the stomach contents and place in a sterile container.
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Instil at least 30mls of sterile water down the tube to obtain as much stomach content as possible.
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Aspirate the contents back and place in the same container.
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Remove the tube, if appropriate.
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Specify on the lab form if this is a routine admission screen for MRSA or for the investigation of a suspected infection.
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For the collection of nose swabs as part of screening for MRSA refer to the policy for the control of Methicillin-resistant Staphylococcus aureus (MRSA).
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If the nose is dry, moisten the swab in sterile 0.9% saline solution beforehand.
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Insert the swab into the anterior nares and direct it up into the tip of the nose and gently rotate. Both nares should be swabbed using the same swab to obtain adequate material.
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Place in transport medium.
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For viral investigation same as above and place in viral transport medium.
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The outside of the nostrils may be rubbed after the procedure to alleviate the unpleasant sensation of swabbing.
This investigation is most commonly used to diagnose whooping cough (Bordetella pertussis). Specimens for PCR (Polymerase Chain Reaction) can be taken in patients under one year of age. For patients over one year of age the requirement for PCR will need to be discussed with microbiology.
Please note: A naso-pharyngeal aspirate is the preferred type of specimen for the diagnosis of Bordetella pertussis. Pernasal swabs may be sent, but it must be ensured that the swab is sent in a sterile, plain dry tube (without transport medium).
When obtaining this specimen the nurse must be proficient in the procedure and ensure suction, oxygen and resuscitation equipment is easily available. The child should be held securely and observed carefully as the procedure may produce paroxysmal coughing and/or vomiting.
Please note: Remember that performing this procedure may generate droplets and/or aerosols, which can expose health care workers to this pathogen. It is therefore essential that appropriate respiratory protection (FFP2 respirator and a visor) are worn when performing this procedure.
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Place the child in a good light to facilitate observation
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Use a sterile soft flocked swab in a plain dry tube (NHS Supply Chain Order Code: HHD128)
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Holding the head upwards, pass the swab along the floor of the nasal cavity to the posterior wall of the naso-pharynx
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Gently rotate and withdraw the swab and place back in the tube. Dispatch immediately to the laboratory to ensure maximum chance of growth of the organism
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A nasopharyngeal aspirate is required for the diagnosis of viral infections such as influenza, parainfluenza and respiratory syncytial virus (RSV). It is also the preferred type of specimen for the diagnosis of Bordetella pertussis infections by PCR and culture.
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Operator must observe standard precautions and wear appropriate personal protective equipment (gloves, apron/gown, FFP2 respirator and visor).
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Attach a mucus trap to the suction system and the appropriately sized catheter, leaving the wrapper on the suction catheter.
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Turn on the suction and adjust the pressure.
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Without applying suction, insert the catheter into the nose, directed posteriorly and towards the opening of the external ear. NB The depth of insertion necessary to reach the posterior pharynx is equivalent to the distance between the anterior naris and external opening of the ear.
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Apply suction and slowly withdraw the catheter using a rotating movement. The catheter should remain in the nasopharynx for no longer than 10 seconds. The trap should be kept upright.
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If necessary rinse the catheter with a small volume of sterile 0.9% saline solution to ensure adequate specimen volume.
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Disconnect suction and seal mucus trap with tubing.
Good quality sputum samples are essential for accurate microbiological diagnosis of pneumonia but also acute tracheitis and bronchitis. Samples contaminated with oro-pharyngeal secretions and saliva are difficult to interpret and can be misleading.
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Encourage the child to cough especially after sleep and expectorate into a container. Alternatively, a poorer sample may be obtained as from naso-pharyngeal/tracheal suction using a sputum trap can be undertaken.
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Physiotherapy may help to facilitate expectoration.
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Ensure the material obtained is sputum and not saliva.
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Specify on the laboratory form if this is a routine admission screen for MRSA or a swab for the investigation of a suspected infection.
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For the collection of throat swabs as part of screening for MRSA refer to the policy for the control of Methicillin-resistant Staphylococcus aureus (MRSA).
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Place the child in a position with a good light source. This will ensure maximum visibility of the tonsillar bed.
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Either depress the tongue with a spatula or ask the child to say “aahh”. The procedure is likely to cause gagging and the tongue will move to the roof of the mouth. This can prevent accurate sampling, therefore it is important to quickly but gently rub the swab over the ansillar fossa (tonsillar bed) or area where there is exudate or a lesion.
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Care should be taken not to contaminate the swab by contact with the tongue or the oral mucosa on removal.
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Return swab to the container with transport medium.
Bedside urine testing for the presence of blood, protein and other analytes is usually undertaken with reagent strips the results of which indicate that further laboratory investigation is required (Higgins 1995c; Cook 1995).
Most urine samples sent to the microbiology laboratory are for bacteriological investigation. The same collection techniques also apply to samples sent for virological investigation.
Urine samples should be dispatched to the laboratory as soon as possible or no more than four hours if kept at room temperature or up to 24 hours if kept at 4 degrees centigrade to avoid overgrowth of organisms and misleading results (Griffiths 1995).
Urine collected from disposable nappies for microscopy and culture analysis has been described (Roberts and Lucas 1985; Vernon 1995; Ahmed et al 1991), however this procedure is not used at the GOSH Trust. Use of specifically designed urine collection pads may be appropriate for other types of samples cannot be obtained.
Normal social hygiene, such as washing the genitalia with soap and water and drying thoroughly is considered sufficient to minimise contamination from the skin prior to collection of the specimen. Assess the clinical and psychosocial needs of the child as to whether cleaning the genitalia is necessary. The nurse must be sensitive to the cultural issues surrounding touching intimate parts of the body.
Collection of urine by a supra-pubic aspirate should be considered when a clean and accurate sample is required. Ultrasound guidance should be used to indicate the presence of urine in the bladder before a supra-pubic aspirate is attempted (National Institute for Health and Clinical Excellence (NICE) 2007).
This is the most reliable non-invasive urine specimen collection method but may not be possible in the very young child. In the female encourage separation of the labia to prevent perineal contamination whilst passing urine. In the male encourage retraction of the prepuce, if appropriate.
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The first part of the urine stream is passed into the toilet to reduce meatal contamination.
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The middle part of the urine stream is collected into a clean container.
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The remaining urine is passed into the toilet.
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Pour the urine into a sterile container.
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Select the correct size sterile urine bag to avoid leakage or contamination with faeces.
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Remove the protective seal.
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For the female place the bag over the vulva, starting from the perineum and working upwards, sticking the bag to the skin.
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For the male, place the bag over the penis and scrotum.
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Observe the bag frequently until urine is passed to avoid leakage.
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Remove the bag and empty the urine through the relevant port into a sterile container.
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Wash the genitalia after the procedure to prevent soreness of the skin.
This is collected from the self-sealing bung of the urinary drainage tubing in a child who is already catheterised. Do not disconnect the closed drainage system as infection may be introduced (DH 2001) nor take the sample from the urinary drainage bag as the specimen maybe contaminated.
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Using an aseptic non-touch technique, clean the catheter sampling site with 2% chlorhexidine/70% alcohol wipe (eg Clinell®) and allow to dry.
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Collect the urine using appropriate sterile equipment appropriate to access port i.e. either using a sterile syringe and needle and inserting the needle into the bung at an angle of 45 degrees; this will minimise penetration of the wall of the tubing and subsequent needle stick injury, or a needle-less system.
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Gently withdraw the urine into the syringe.
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Remove the needle and syringe, wipe the area with the alcohol swab and allow to dry. The rubber bung will self-seal.
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Place the urine in a sterile container.
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Discard the needle and syringe into a sharps container.
The specimen should be obtained by a nurse who is familiar with the Mitroffanof operation and the specific anatomy of the area on the child.
The taking of this specimen in children should be avoided where possible due to its invasive nature.
In the case of suspected or actual sexual abuse:
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Local child protection protocols must be adhered to.
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Do not clean the area as identification of semen or sexually transmitted diseases may be required for evidence.
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If specimens are to be taken in house (rather than by a forensic medical officer or at a genitourinary medicine clinic), contact the virology department who will provide the appropriate swab and transport media. Because these tests are referred to an external laboratory and are infrequently performed, swabs may not be immediately available and testing may be delayed pending request for swabs.
For investigation of simple vaginal discharge:
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Expose the vaginal area and part the labia.
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Use routine charcoal swab - gently insert the supplied swab into the outer entrance of the vagina. Care must be taken not to tear the hymen.
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Place the swab into the supplied transport medium.
Vesicle fluid may be collected in to a syringe or onto a swab and placed in viral transport medium for testing by PCR.
Explain to the child and parent that the procedure is usually pain free as the needle only penetrates the vesicle not the skin.
The vesicular fluid should be screened by PCR to confirm the clinical diagnosis such as varicella-zoster (chickenpox or shingles) or herpes simplex type 1 or 2.
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Obtain a sterile syringe and needle, sterile swab and viral transport medium.
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Pierce the top of the vesicle with a sterile needle and if there is sufficient fluid draw up the exudate into a syringe. Keep the needle flush to the skin to prevent accidental stabbing if the child moves. Then draw up some viral transport medium into the syringe and flush the medium plus vesicle fluid back into the bottle of viral transport medium. Dispose of the needle in a “sharps” bin.
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Send the sample with a request for Varicella-zoster and Herpes simplex PCRs.
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Place a sterile dressing over the vesicle until dry.
If the vesicle is already dry, a positive diagnosis may be reached from a swab which has been vigorously rubbed over the dry base and sent in viral transport medium. If fluid is easy to collect the vesicle may be punctured and fluid collected on a swab which is then placed in the viral transport medium.
Interpretation of results must be in conjunction with clinical signs. In the absence of clinical signs of infection wound swabs will provide little if any useful information and simply reflects colonisation (Gilchrist 1996).
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Obtain the specimen prior to any dressing or cleaning procedure of the wound. This will maximise the material obtained and prevent killing of the organism by the use of antiseptics.
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Use a sterile swab and gently rotate on the area to collect exudate from the wound and place into transport medium. Where there is pus collect as much as possible in a sterile syringe or sterile container (do not use a swab) and send to the laboratory.
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For detection of Mycobacterium tuberculosis, pus collected neat in to a pot or tissue biopsy is preferred, however a calcium alginate swab can be used. The alginate swab gradually dissolves maximising the isolation of the organism as the number of organisms are usually small.
Specimens are taken to detect carriage of MRSA either before or on admission or as part of a screening process in the event of cases or an outbreak of MRSA.
As part of the routine admission screen each patient should have a nose and throat swab taken.
NB Children with epidermolysis bullosa do not need to have a nose or throat swab taken as this may cause mucosal damage.
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If the nose is dry, moisten the swab in sterile 0.9% saline solution beforehand.
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Insert the swab into the anterior nares and direct it up into the tip of the nose and gently rotate. Both nares should be swabbed using the same swab to obtain adequate material.
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Return the swab to the container with the transport medium.
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The outside of the nostrils may be rubbed after the procedure to alleviate the unpleasant sensation of swabbing.
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Place the child in a position with a good light source. This will ensure maximum visibility of the tonsillar bed.
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Either depress the tongue with a spatula or ask the child to say “aahh”. The procedure is likely to cause gagging and the tongue will move to the roof of the mouth. This can prevent accurate sampling, therefore it is important to quickly but gently rub the swab over the ansillar fossa (tonsillar bed).
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Care should be taken not to contaminate the swab by contact with the tongue or the oral mucosa on removal.
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Return swab to the container with transport medium.
Patients that have previously been screened positive for MRSA should in addition to the nose and throat swabs also have swabs taken from the following sites:
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hairline (swab along outline of scalp hair)
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axillae
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groin
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perineum
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any wounds or skin lesions
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umbilicus (only in neonates)
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insertion sites of devices (eg tracheostomy, gastrostomy, central venous catheter)
When taking samples from intact skin the swab should be moistened with sterile 0.9% saline solution before sampling as this assists in the transfer of bacteria from the sampling site to swab and can increase the number of micro-organisms collected (Perry 2007).
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Requests have to be discussed with a Consultant Microbiologist or Clinical Scientist if uncertain if specimen suitable or what tests are available.
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Specimen collection - material needs to be sent in a plain sterile container without any transport medium or fluid. EDTA blood may be sent.
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Suitable specimens: Broad range 16S PCR may be performed on specimens from any normally sterile site eg empyema, pericardial fluid, joint aspirate, CSF, tissue and pus. Testing is usually delayed until after primary culture results are known.
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Suitable specimens: Broad range 16S PCR may be performed on specimens from any normally sterile site eg empyema, pericardial fluid, joint aspirate, CSF, tissue and pus. Testing is usually delayed until after primary culture results are known.
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Positive results will be telephoned to discuss significance.
Reference 1:
Higgins C (1994) An introduction to the examination of specimens. Nursing Times 90(47) 29-32.
Reference 2:
Ethics Advisory Committee (1992) Guidelines for the Ethical Conduct of Medical Research Involving Children. British Paediatric Association.
Reference 3:
Health Services Advisory Committee (1986) Guidance on the Labelling, Transport and Reception of Specimens. Health and Safety Commission: London.
Reference 4:
Advisory Committee on Dangerous Pathogens (2004) Approved List of Biological Agents Health and Safety Executive: London.
Reference 5:
Advisory Committee on Dangerous Pathogens (1998) Precautions for work with human and animal Transmissible Spongiform Encephalopathies. HMSO: London.
Reference 6:
Advisory Committee on Dangerous Pathogens (1996) Management and Control of Viral Haemorrhagic Fevers. HMSO: London.
Reference 7:
Safety Action Bulletin (1990) Spills of urine: Potential risk of misuse of chlorine-releasing disinfecting agents. SAB (90) 41.
Reference 8:
Expert Advisory Group on AIDS (1990) Guidance for Clinical Health Care Workers: Protection Against Infection with HIV and Hepatitis Viruses. HMSO: London.
Reference 9:
Higgins C (1995a) Microbiological examination of blood for septicaemia. Nursing Times 91(16) 34-35.
Reference 10:
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Lead author(s)
Deirdre Malone, Lead Nurse, Infection Control
Contributing author(s)
Barbara Brekle, Deputy Lead Nurse, Infection Control
John Hartley, Consultant Microbiologist, Infection Control
Document owner
Deirdre Malone, Lead Nurse, Infection Control
Approved by
Clinical Practice Committee
First introduced: 01 February 2003
Date approved: 01 November 2011
Review schedule: Two years
Next review: 31 October 2013
Document version: 4.0
Replaces version: 3.0
