Since the 1930s, carbon dioxide (CO2) has been combined with cold storage for the preservation of food. However, its use for the prevention of surgical wound infection was long considered to be impractical. Now CO2 is widely used during laparoscopic procedures, and a method has been developed to create a CO2 atmosphere in an open wound. The aim of this study was to investigate the effect of CO2 on the growth of Staphylococcus aureus at body temperature.
First, S. aureus inoculated on blood agar were exposed to pure CO2 (100%), standard anaerobic gas (5% CO2, 10% hydrogen, 85% nitrogen), or air at 37°C for a period of 24 h; then a viable count of the bacteria was made. Second, S. aureus inoculated in brain–heart infusion broth and kept at 37°C were exposed to CO2 or air for 0, 2, 4, 6, and 8 h; then the optical density of the bacteria was measured.
After 24 h, the number of S. aureus on blood agar was about 100 times lower in CO2 than in anaerobic gas (p = 0.001) and about 1,000 times lower than in air (p = 0.001). Also, in broth, there were fewer bacteria with CO2 than with air (p < 0.01). After 2 h, the number of bacteria was increased with air (p < 0.001) but not with CO2 (p = 0.13). After 8 h, the optical density had increased from zero to 1.2 with air but it had increased only to 0.01 with CO2 (p = 0.001).
Pure CO2 significantly decreased the growth rate of S. aureus at body temperature. The inhibitory effect of CO2 increased exponentially with time. Its bacteriostatic effect may help to explain the low infection rates in patients who undergo laparoscopic procedures.