The Ultimate Guide to Medical Specimen Collection and Transport
(6) Directly inoculate the specimen into appropriate culture media [such as tryptic soy broth and thioglycollate medium or standard blood culture bottles].
Urine specimens are usually collected using the clean-voided method. Before collection, the urethral opening should be cleaned with soap and water (patient education is necessary; currently, most major hospitals do not emphasize this requirement for urine collection). Discard the first part of the urine stream, collecting the mid-stream or near-end stream in a sterile container. Catheterization for urine collection (especially for female patients) should be avoided unless necessary, as it can lead to urinary tract infections. The collection method must be noted on the lab form, along with any recent antibiotic treatment. These two points should be included on the test requisition form. If the specimen cannot be transported or cultured immediately after collection, it should be refrigerated (4-8°C) for no more than 6 hours. Urine specimens are not used for gonorrhea testing.
Swab specimens can be directly inoculated onto appropriate media [such as chocolate agar and modified Thayer-Martin agar], or placed in special transport media/devices (containing CO2 and modified Thayer-Martin agar). Refrigerated isolation or transport media should be brought to room temperature or 35°C for about half an hour before use, as Neisseria gonorrhoeae is temperature-sensitive. Chocolate agar should contain IsoVitaleX or supplement B to increase isolation rates. For prenatal Group B Streptococcus (GBS) screening at 35-37 weeks of pregnancy, genital swabs can be directly placed in GBS selective broth or LIM selective enrichment broth to increase GBS isolation rates.
CSF is usually obtained through lumbar puncture, performed by a physician as follows: The lower back is disinfected with 70% alcohol or 2% iodine tincture (as with blood specimen collection) and anesthetized. A special stylet needle is then gently inserted between the third and fourth lumbar vertebrae along the midline into the spinal subarachnoid space. The entire process must be conducted under the strictest aseptic conditions. For infants or children, position the head and hands on folded sheets or blankets, or place the head on the abdomen to facilitate lumbar puncture. Distribute the CSF into 3 small sterile tubes [using a Sterile 3-tube Set for CSF is convenient]. Then quickly send the third (or first) tube to the microbiology laboratory.
For microbial examination of fecal or rectal swab specimens, rapid transport and inoculation are crucial. Delays may allow overgrowth of non-pathogenic intestinal bacteria, making pathogen isolation difficult.
Pus or wound specimens often require anaerobic culture, so great care must be taken during collection to minimize exposure to air. It's best to aspirate specimens directly from the lesion with a syringe; if swabs must be used, place them in Anaerobic TransCult Swab medium, or insert the needle through a silicone stopper, or inject into an anaerobic specimen collection vial [Anaerobic vial], then quickly send to the laboratory for inoculation onto appropriate media.
When Corynebacterium diphtheriae infection is suspected, perform both throat and nasal-pharyngeal cultures to increase isolation rates. If diphtheria-like lesions are present in the throat, in addition to culture, direct smears should also be made, as the causative organisms of Vincent's angina, which can resemble diphtheria, can only be detected through smear examination.
The nasopharynx refers to the upper half of the throat behind the soft palate. To collect specimens from this area, use a thin, flexible-handled nasopharyngeal flocked swab. Insert it through the nasal cavity into the nasopharynx, gently rotate to swab, then withdraw. Repeat through the other nostril. After collection, place in the aforementioned Amies transport medium or Aerobic TransCult Swab and quickly send to the laboratory. Care must be taken to avoid saliva contamination during nasopharyngeal specimen collection.
Children often swallow sputum into their stomachs, and adults may do so during sleep. To collect sputum from children or when satisfactory coughed sputum cannot be obtained from adults, gastric contents can be aspirated, preferably before eating or drinking in the morning. For microbial examination of bronchial secretions, specimens can be obtained using a bronchoscope.
Body fluid specimens such as pleural fluid, peritoneal fluid, pericardial fluid, or synovial fluid are usually collected by physicians using aseptic technique. A trocar or specially designed needle is inserted into the collection site, and fluid is aspirated with a syringe. Since all fluids require anaerobic culture, collection and transport should avoid air contact. They can be directly inoculated into blood culture bottles and/or collected in anaerobic transport tubes.
Conjunctival specimens can be collected using a swab moistened with sterile saline. Care must be taken to avoid spreading infection to adjacent eye areas. After collection, swabs should be placed in Amies transport medium or TransCult Swab to prevent drying. Note that the specimen should be labeled as from the left or right eye.
To collect skin specimens, first clean the lesion area with 70% alcohol, then use a sterile blade or slide edge to scrape specimens from the lesion margins and place them in a sterile culture dish. Nail specimens are collected similarly, but it's necessary to scrape deeper into newly infected nail tissue. For hair or scalp scale specimens, a Wood's lamp (ultraviolet light) can be used to illuminate the affected area, as infected areas often fluoresce. Then, use sterile forceps to pluck hair or scalp scales and place them in a sterile culture dish.
Mantacc Swab Supply
Our flocked nasopharyngeal swab uses a medical-grade ABS shaft with a flocked tip design. The flocked swab is manufactured using spray and electrostatic charge methods, allowing millions of nylon fibers to adhere vertically and uniformly to the handle end. The capillary action between the nylon fibers facilitates sample collection and elution. Flocked swabs have far superior sample collection and release capabilities compared to traditional twisted swabs. They are thin, soft, and mainly used for nasopharyngeal sampling of respiratory diseases such as COVID-19, influenza A and B, respiratory syncytial virus, and mycoplasma pneumoniae.