2 Blood Culture Collection

Purpose and preparation

Blood cultures detect microorganisms circulating in the bloodstream. Collecting too little blood can reduce the chance of detecting infection, while contamination by skin organisms can lead to misleading results. Follow the facility’s approved procedure and the bottle manufacturer’s instructions.

Patient, site, and bottle preparation

Confirm the order and identify the patient using at least two identifiers. If possible, collect cultures before antimicrobial therapy begins. Gather the correct bottles and collection equipment; an adult set commonly contains an aerobic and an anaerobic bottle, but required volumes vary by bottle system and local protocol.

Choose an appropriate peripheral venipuncture site. When multiple sets are ordered, use separate sites as directed by the clinical protocol. Perform hand hygiene and use appropriate personal protective equipment.

Clean visibly soiled skin first. Apply an approved skin antiseptic using the required friction and contact time, then allow the site to dry completely. Do not touch the prepared site; if repalpation is necessary, use sterile gloves. Use an antiseptic appropriate for the patient and follow local policy, especially for infants.

Disinfect each bottle’s rubber septum with 70% isopropyl alcohol and allow it to dry before inoculation. Do not touch the cleaned septum. These preparation steps help prevent skin or environmental organisms from entering the specimen.

Volume and bottle order

Collect the prescribed volume using a sterile venipuncture technique. For adults, the usual target described by CDC is 20–30 mL per set, commonly divided between aerobic and anaerobic bottles. The bottle’s fill marks and facility protocol determine the correct amount; do not overfill or underfill. For children, follow the age-, weight-, and bottle-specific protocol rather than adult volumes.

Bottle sequence depends on the collection method:

• Direct collection with a butterfly set: Usually inoculate the aerobic bottle first, then the anaerobic bottle. Air in the tubing can enter the first bottle, so this order helps protect the anaerobic bottle.

• Blood drawn into a syringe and then transferred: Many procedures inoculate the anaerobic bottle first, then the aerobic bottle, to limit air introduced into the anaerobic bottle.

These are common approaches, not universal rules. Bottle design and validated local procedures can differ, so follow the collection system’s instructions. If other blood specimens are collected during the same venipuncture, collect blood cultures first to reduce the risk of contamination from additives in other tubes.

Handling, labeling, and transport

Gently mix each inoculated bottle as directed by its manufacturer; avoid vigorous shaking. Label bottles at the collection site with the required patient identifiers. According to facility policy, document the collection date and time, anatomic site, collection method, and collector; record the amount collected when required.

Transport bottles promptly to the laboratory. If a delay is unavoidable, follow laboratory instructions. Routine blood-culture bottles are generally kept at room temperature and not refrigerated.

• Aseptic technique