Specimen Collection and Transport

• The lecture covers specimen collection and transport with the goal of enabling students to classify specimens, recognize proper collection and transport techniques, identify rejection criteria, and understand infection prevention.

Diagnosis of Bacterial Infections

• Direct methods involve examining the specimen, while indirect methods involve serological tests to detect antibodies.

Specimen Quality

• A 'good quality' clinical specimen is crucial for accurate infection diagnosis.

Obtaining Quality Specimens

• Collect specimens before starting antibiotics when possible.
• Choose specimens that represent the actual infection site.
• Use sterile containers for microbiological specimens.
• Avoid specimen contamination during collection.
• Transport specimens promptly to the lab, using transport media if necessary.

Proper Specimen Selection

• Selection should be based on the suspected infectious disease; e.g., throat swab for pharyngitis, sputum for pneumonia, cerebrospinal fluid (CSF) for meningitis, urine for UTIs, and stool for diarrhea.

Proper Collection Techniques

• Identify the necessary number, volume, and collection time of specimens.
• Collect specimens during the acute phase of infection.
• Maintain strict aseptic conditions to minimize contamination.
• Obtain the specimen before starting antibiotic therapy if feasible.
• Provide clear instructions to patients who collect their own specimens (e.g., sputum or urine).
• Use sterile specimen containers (except for stool), properly labeled, and accompanied by a lab request.

Lab Request Form Details

• Requests should include patient name, age, sex, location (department, ward, room number), physician's name, specimen type, collection date and time, clinical diagnosis, and antimicrobial therapy details.

Methods of Sample Collection

• Samples are collected through aspiration (pus, blood for blood culture), swabbing (throat swab), endoscopic specimens (bronchoalveolar lavage, gastric biopsy), or surgical specimens.

Specimen Types

• Examples of specimens include swabs, stool samples, universal containers, sterile containers, blood tubes and blood culture bottles.

Blood Culture

• Blood is normally sterile, bacteremia is the presence of bacteria in the bloodstream, and septicemia signifies bacteria and/or toxins in the bloodstream.
• A blood culture is performed to diagnose bacteremia.

Collecting Blood for Culture

• Standard precautions must be applied because blood-borne viruses such as hepatitis B, hepatitis C, and HIV may be transmitted.
• Perform hand hygiene, wear gloves, and use aseptic techniques.
• Disinfect the patient's skin with 70% alcohol (± betadine) in a concentric swabbing motion, allowing it to air dry.
• Do not touch the disinfected skin site again.
• Always disinfect the tops of blood culture bottles with 70% alcohol.
• Usually obtain 10 ml of blood for adults and 3-5 ml for children, injecting it immediately into the labeled and incubated blood culture bottle.
• Collect two sets of blood cultures from two different veins and do not recap syringes and needles and dispose of them in a safety box.

Skin Specimens

• Collect pus from abscesses by aspirating with a sterile needle and syringe after decontaminating the skin.
• Wounds are sampled best with a sterile needle and syringe or a sterile swab.

Eye and Ear Specimen Collection

• Use separate sterile swabs to sample the conjunctiva of both eyes, even if only one eye is infected.
• For otitis media, the ideal specimen is fluid aspirated from behind the ear drum with a sterile needle and syringe; using a sterile swab is not recommended unless the eardrum has ruptured.
• Eye and ear specimens should never be refrigerated.

Respiratory Specimens

• Specimens from the Upper Respiratory Tract Infections include throat and nasal swabs, nasopharyngeal swabs and washes.
• Sputum is the pus that accumulates in the lungs of a patient with pneumonia.
• Sputum specimens are collected preferably in the early morning and sputum, not saliva, needs to be collected.
• If tuberculosis (TB) is suspected, up to 3 morning sputum specimens are required.
• Other LRT specimens include Bronchoalveolar lavage; BAL

Central Nervous System (CNS) Infections

• Collect CSF specimen through lumbar puncture in cases of meningitis.
• The procedure must be performed under strict aseptic conditions by a physician.
• CSF specimens must be rapidly transported without refrigeration to maintain viability.

Urine Collection

• A midstream urine sample is most common.
• Use sterile, dry, wide-necked, leak-proof containers.

Obtaining Midstream Urine Sample

• Wash hands.
• Cleanse the area around the urethral opening with clean water.
• Dry the area with a sterile gauze pad.
• Collect the sample from the middle of the urine flow.

Indwelling Catheter Urine Collection

• Clean the port vigorously with 70% alcohol; aspirate urine with a sterile needle and syringe.
• Do not collect urine from the collection bag.

Pediatric Urine Collection

• Toilet-trained older children are instructed to collect a midstream urine sample, whereas, samples are collected by a sterile pediatric urine collector bag for non-toilet-trained children.
• If previous methods are not possible, a suprapubic needle aspiration or urinary catheter is used.

General Urine Specimen Guidelines

• Urine specimens are collected in the early morning.
• The lab only accepts a urine specimen that is held at room temperature for less than 2 hours or refrigerated for less than 24 hours.

Stool Specimen and Rectal Swab Specimens

• Diarrheal stool or rectal swabs are used with infants and children where obtaining stool is difficult.

Number of Specimens

• Collect at least 2 sets of blood cultures in 24 hours.
• 3 successive morning sputum samples for TB.
• Perform Paired sera (2 serum samples 1-2 weeks apart) for serological investigations to detect rising antibody titer.

Proper Transport

• Specimens should be delivered to the lab as soon as possible.
• If delivery is delayed, use a transport medium to prevent pathogen death.
• Place some specimens on ice during delivery, whereas others should never be refrigerated.
• Consider all clinical specimens as potential biohazards.
• Universal precautions must be taken.

Specimen Rejection Criteria

• Specimens without proper patient identification.
• Specimens received in poor condition (e.g., dry swab or leaking container).
• Prolonged transport times such as with urine samples held at room temperature for >2 hours.
• Specimens received in formalin for microbiological testing.