* Oxygen Sensitivity: Anaerobic bacteria are sensitive to oxygen and can be killed or inhibited by its presence. Drawing aerobic cultures first would expose the site to oxygen, potentially compromising the anaerobic culture.

* Contamination Risk: Drawing aerobic cultures after anaerobic cultures increases the risk of contaminating the anaerobic culture with oxygen-loving bacteria from the environment or the patient's skin.

The proper order for drawing cultures is:

1. Anaerobic Culture: This is done first to minimize oxygen exposure and ensure the recovery of anaerobic organisms.

2. Aerobic Culture: This can be drawn afterwards, as the site will already be exposed to oxygen.

This order helps to maximize the chances of isolating both aerobic and anaerobic bacteria, leading to a more accurate diagnosis and treatment plan.