Presentation of a pathogenic organism(s), particularly microbiological in nature, in a patient specimen is a definitive means for identification and clinical diagnosis. However, failure to confirm a pathogen in a specimen may indicate that:

1. The pathogen was absent or scant in that specimen.
2. The sample was taken at a stage of the disease when the pathogen was limited in presence.
3. Viability was lost between the times of collection and arrival in the laboratory.
4. The pathogen cannot be detected by this method of testing.

Specimens for culture MUST be collected properly prior to the initiation of antibiotic therapy to insure optimal conditions for the recovery of pathogens.

The laboratory will identify isolates suspected of clinical presentation and perform antibiotic susceptibility testing where appropriate.

Anaerobic and blood cultures are not available through the Public Health Lab.

TESTS OFFERED

• Stool Culture
• Urine Culture
• Throat Culture
• Wound or Miscellaneous Culture
• Tissue Culture
• Genital Culture
• Carbapenemase Detection - modified Carbapenemase Inactivation Method (mCIM) and molecular detection by real time PCR (listed above)
• Confirmation of Enteric Pathogens - Salmonella species. Shigella species, Shiga-toxin-producing E. coli (STEC), Listeria monocytogenes, Vibrio species, Campylobacter spp.
• Pathogenic microorganism identification (MALDI-ToF)
• Antibiotic Susceptibility Testing
• Non-Candida albicans yeast surveillance testing

SAMPLE COLLECTION, HANDLING AND TRANSPORT

Collection kits are available for routine cultures upon request. Each kit contains a transport system composed of a sterile swab and transport medium. Order the tests requested in LIMS or use DPHL requisition form.

• Herpes/Viral/Flu/Pertussis Collection Kit
• Bacterial Stool/Urine Collection Kit

RESPIRATORY TRACT SPECIMENS:

Complete Throat Culture:

1. Collect specimen under good lighting. Depress the tongue with a tongue blade and pass the swab firmly over the back of the patient's throat, tonsils or tonsillar fossae and any area of inflammation and or exudation.
2. Return the collection swab to the transport tube.
3. Label the swab transport tube with at least two unique patient identifiers (i.e., patient name and date of birth), along with collection date/time.
4. Complete the requisition form or order test directly in LIMS.
5. Place specimen and requisition in pouch for pickup by a lab courier or arrange to have specimen taken to a courier pickup site. Contact the laboratory for a list of pickup sites. DO NOT mail specimen(s).

Sputum Culture:

1. An early morning specimen is recommended. A volume of 5 to 10 ml is adequate and there is no advantage in collecting a larger volume. The sample should contain recently discharged material from the bronchial tree with minimal saliva content.
2. Upon rising in the morning, rinse mouth well with water (not mouthwash).
3. Inhale as deeply as possible. Expectorate into sputum collection container, available from the Laboratory, while coughing as deeply and vigorously as possible.
4. Tightly cap container so no spillage occurs.
5. Wash and dry outside of container and label the SPECIMEN CONTAINER with at least two unique patient identifiers (i.e., patient name and date of birth), along with collection date/time.
6. Complete the requisition form or order test directly in LIMS.
7. Place form and specimen container in pouch for pickup by lab courier or arrange to have specimen taken to a courier pickup site. Refrigerate specimen while waiting for pickup. Do not mail specimen. Specimens must be processed by the laboratory within 24 hours.
8. If more than one specimen is requested (for example, 3 AFB cultures are requested), collect only one specimen per day, first thing in the morning. Have specimens delivered to the Laboratory DAILY. Do not wait until all three have been collected.

WOUND AND MISCELLANEOUS SPECIMENS

Sterile transport swabs and requisition slips are available for routine cultures from the Division of Public Health Laboratory upon request.

1. Collect specimen under good lighting. Pass the swab firmly over or into an area of suspected infection and obtain a sample of exudate, drainage, or purulent discharge if these are present.
2. Return the swab to the transport tube.
3. Label the swab transport tube with at least two unique patient identifiers (i.e., patient name and date of birth), along with collection date/time.
4. Complete the requisition form or order test directly in LIMS. Indicate the area of the body from which wound specimen was taken to assist in distinguishing normal from abnormal flora (ears, legs, etc).
5. Place specimen and requisition in pouch and promptly deliver to lab pickup site. DO NOT mail specimen.
   • NOTE: Specimens collected on these swabs should be delivered to laboratory within 24 hours in order that they be plated ASAP after collection. Transport swabs that are 24-72 hours old are acceptable if refrigerated.

TISSUE

Handle in same manner as miscellaneous specimens above; however, instead of sterile transport swab, place tissue specimen in sterile container with a small amount of sterile saline or sterile water to keep specimen from drying out. Be sure container is labeled with name of patient and source of specimen.

STOOL SPECIMENS

The recovery of bacterial pathogens from fecal specimens will help confirm the diagnosis of bacterial gastroenteritis as manifested by diarrhea and/or dysentery. DPHL routinely screen stools for Campylobacter, Salmonella, Shigella, and Shiga toxin E.coli. If other pathogens are suspected, please indicate on request form.

Norovirus cannot be tested by stool culture but can be detected by real time PCR molecular methods. For Norovirus stool collection - collect teaspoon size sample in sterile leak-proof container with no preservatives along with test requisition form. Store samples in refrigerator at 3-9 degrees Celsius.

1. Obtain a collection kit containing Cary Blair transport media from this laboratory.
   • NOTE: The enteric kits have an expiration date. If kits are expired, return them to this laboratory for replacement.
2. Collect feces from patients as soon after onset of illness as possible, and before the start of treatment. Specimens may be obtained by covering the rear half of the toilet rim below the seat with plastic kitchen wrap to catch feces.
3. Transfer a sample (no more than one ounce) of the specimen using the spatula attached to the container lid into the Cary Blair medium supplied in the kit and mix thoroughly. Dispose the unused specimen in the toilet, rinse the plastic in the toilet and dispose in the trash.
4. For liquid stool specimens, no more than 10 ml (1/3 oz) should be added to the Cary Blair medium and mixed.
5. Complete the requisition form or order test directly in LIMS.
6. Place the specimen and requisition form in the transport pouch and arrange for courier pickup. DO NOT mail. Specimens must be processed by the laboratory within 72 hours of collection.
   • NOTE: Do not ship stool cultures without using the Cary Blair transport medium.
7. If a rectal swab is used, be certain to insert swab past the sphincter muscle (1 1.5 inch) to obtain a fecal specimen. Place swab into Cary Blair and break off upper stem so that lid can be replaced for shipping. Proceed with shipment of specimen as above.

Norovirus cannot be tested by stool culture but can be detected by real time PCR molecular methods. For Norovirus stool collection - collect teaspoon size sample in sterile leak-proof container with no preservatives along with test requisition form. Store samples in refrigerator at 3-9 degrees Celsius.

URINARY TRACT SPECIMENS

The lower third of the male urethra and the labia surrounding the female urethra are normally colonized by large numbers of bacteria, some potentially pathogenic. Urine is normally sterile but is an excellent culture medium for the rapid growth of bacteria. Failure to cleanse the patient properly around the urethra prior to obtaining a specimen will result in contamination and bacterial overgrowth of the urine sample.

To minimize specimen contamination on collection, use the "clean catch" technique. 

1. Obtain a URINE CULTURE COLLECTION KIT from the laboratory.
2. Collect clean catch specimen according to directions listed below, or as detailed in your own procedures.
3. Complete the requisition form or order test directly in LIMS.
4. Place completed form and specimen in transport bag, transport to lab pickup site and REFRIGERATE. DO NOT mail. Specimens should be delivered to the laboratory within 24 hours for processing.

Urine Culture Collection

1. Wash hands with soap and water, rinse and dry.

2. WASH area around urethra with soap.

3. RINSE area with warm water.

4. VOID- Pass the first portion of urine into the toilet and then pass a portion (1 ounce) of the remaining urine into a sterile container. Pass the rest of the urine into the toilet, close and label the container with name and date. Store samples in refrigerator

GENITAL TRACT SPECIMENS

Genital Culture:

Allows DPHL to detect bacterial pathogens, as well as fungal elements in culture. Common pathogens include but are not limited to bacterial vaginosis (BV) by Gardnerella vaginitis, Streptococcus agalactiae (Group B Strep), Haemophilus ducreyi, and yeast species identification.

1. Use swab to obtain a sample of endocervical, vaginal, or urethral discharge. Return the swab to the transport tube and break the media ampule at the base of the tube to moisten the swab. Please follow the manufacturer's directions.
2. Label the swab transport tube with the patient's name. Complete the requisition form or order test directly in LIMS.
3. Place specimen and requisition in pouch and transport to the lab pickup site for pickup by lab courier. DO NOT mail specimen.
4. Special media and transport containers are required when culturing for gonorrhea. Contact Clinical Micro section of the laboratory for further instructions.

Gonorrhea Culture:

DPHL tests for detection of Neisseria gonorrhoeae by nucleic acid amplification testing (NAAT), together with Chlamydia trachomatis. NAAT testing is sensitive and remains the recommended method for gonorrhea and chlamydia screening. More information on NAAT testing can be found NUCLEIC ACID AMPLIFICATION TESTS FOR CHLAMYDIA, GONORREA AND TRICOMONAS. Due to the fastidious nature of Neisseria gonorrhoeae, DPHL offers specific instructions for specimen collection for test of cure and antimicrobial resistance investigations. DPHL currently uses an enclosed modified Thayer martin (MTM) selective system for the culturing of gonorrhea. Supplies are provided by DPHL and include instructions for inoculating the selective agar.

1. ENDOCERVICAL: preferred site for specimens from females.
   1. Specimen collection should be done with a sterile swab. Cytobrush is not recommended as it may cause trauma and bleeding that can render the specimen unsatisfactory.
   2. Rotate swab against the wall of the endocervical canal several times for 20-30 seconds and withdraw the swab without touching the vaginal surface.
   3. Inoculate MTM GC selective plate and send both the inoculated plate and the original swab to DPHL.
   4. The order of testing for specimen collection should be GC culture, Pap smear, then Chlamydia/GC NAAT test. Since the visible presence of blood may interfere with test results, it is advisable to collect the Pap smear last when using the cytobrush because of induced bleeding that might occur.
   5. Speculum should be lubricated with water only.
2. URETHRAL: preferred site in men, or in women with no cervix (e.g. post-hysterectomy).
   1. Delay obtaining specimens until 2 hours after patient has last voided.
   2. Obtain specimens for gonorrhea culture first, BEFORE specimens for Chlamydia or Pap smear.
   3. Gently insert the urogenital swab into the urethra (women 1-2 cm, men 2-4 cm). Rotate the swab in one direction for at least one revolution for a minimum of 10 seconds. Withdraw the swab and inoculate MTM GC selective plate.
   4. Send DPHL both the inoculated plate and the original swab.
3. OROPHARYNX (THROAT):
   1. Swab the back of throat and tonsillar area with a sterile swab and inoculate the MTM GC selective plate.
   2. Send DPHL both the inoculated plate and the original swab.
4. RECTAL:
   1. Insert sterile swab approximately 1-1.5 inches in the anal canal. Move swab from side to side in the anal canal to sample crypts.
   2. Allow swab to remain 10-30 seconds for absorption of organisms onto the swab.
   3. Withdraw the swab and inoculate MTM GC selective plate.
   4. Send DPHL both the inoculated plate and the original swab.

TESTS

Cultures are plated on a variety of selective and non-selective media based on currently recommended guidance for screening different body sites. Cultures are incubated overnight, then examined for normal flora and potential pathogens. Potential pathogens are identified with a variety of methods, and susceptibility testing is performed when warranted.

RESULTS

Laboratory results are reported in LIMS and reports are available to print as they are completed. Expected turnaround times are as follows:

Throat Culture	one business day
Respiratory (Nasopharyngeal, Sputum)	two business days
Wound & Miscellaneous	two business days
Fecal	two - three business days
Urine	two business days
Gonorrhea Culture	three business days
Genital Tract	two business days

 

REJECTION

Samples will be rejected if they are:

• Unlabeled - All specimens MUST be labeled with at least two unique patient identifiers at a minimum.
• Insufficient in quantity - No specimen received, no specimen in container, or insufficient specimen to perform testing.
• Improperly preserved - Specimens must be received in the transport media as defined by the laboratory.
• Damaged - Specimen leaked or broken in transit.
• Too old - Aged specimens are diagnostically unreliable. The following chart details the MAXIMUM acceptability per source:

LINKS

Test Requisition Form

Combined Laboratory Specimen Collection Procedures

Return to Laboratory Specimen Collection Procedures page.

Return to the Delaware Public Health Laboratory page

This page was last updated 4/24

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