Evaluating the efficacy of disinfecting agents against Staphylococcus aureus on external fixator devices.

OBJECTIVE

The objective of this study was to evaluate and compare the efficacy of multiple disinfectant agents commonly used to remove bacteria from external fixators infected with Staphylococcus aureus.

METHODS

A sterile external fixator was colonized with Staphylococcus aureus for 48 h to allow biofilm formation on the device. Following incubation, the device was treated with one of the following: Isopropyl Alcohol (IPA), Chlorhexidine Gluconate Scrub (CHG) + IPA, Betadine (PI) + IPA, or ChloraPrep (2% CHG and 70% IPA). Swabs were taken from locations on each device and plated on Tryptic Soy Agar (TSA) plates. Colony forming units (CFUs) were counted and analyzed using Kruskal-Wallis tests along with Dunn's multiple comparisons. The frequency of zero vs. detectable (non-zero) CFU data was also recorded.

RESULTS

The median in the control group was 7.8 × 103 CFUs (interquartile range (IQR): 1.5 × 103-2.2 × 104 CFUs), compared to a median of 0 CFUs in each treatment group (IPA IQR: 0-0; CHG+IPA IQR: 0-0; ChloraPrep IQR: 0-7.5; Betadine+IPA IQR: 0-3.8 × 102). Three non-zero data were recorded in the IPA group (n = 16), two non-zero data were recorded in the CHG + IPA group (n = 16), four non-zero data were recorded in the ChloraPrep group (n = 16), and seven non-zero data were recorded in the Betadine + IPA group (n = 16). Kruskal-Wallis analysis indicated that all disinfectant groups had significantly fewer bacteria compared to controls (P < 0.05). There was no significant difference between any of the disinfectant groups.

CONCLUSIONS

All disinfectants significantly reduced the bacterial load on the external fixators, supporting their safety in the sterile field. While there was no statistically significant difference in CFUs between disinfectants, the CHG + IPA group had the highest frequency of zero CFU data. In contrast, the Betadine + IPA group had the highest frequency of non-zero CFUs and the widest IQR of 0-3.8 × 102 CFUs.

LEVEL OF EVIDENCE: IV.