Surgical site infection (SSI) is the most common complication of surgery, increasing healthcare costs and hospital stay. Chlorhexidine (CHX) and povidone-iodine (PVI) are used for skin antisepsis, minimising SSIs. There is concern that  resistance to topical biocides may be emergeing, although the potential clinical implications remain unclear. The objective of this systematic review was to determine whether the minimum bactericidal concentration (MBC) of topical preparations of CHX or PVI have changed over time, in microbes relevant to SSI. We included studies reporting the MBC of laboratory and clinical isolates of common microbes to CHX and PVI. We excluded studies using non-human samples and antimicrobial solvents or mixtures with other active substances. MBC was pooled in random effects meta-analyses and the change in MBC over time was explored using meta-regression. Seventy-nine studies were included, analysing 6218 microbes over 45 years. Most studies investigated CHX (93%), with insufficient data for meta-analysis of PVI. There was no change in the MBC of CHX to Staphylococci or Streptococci over time. Overall, we find no evidence of reduced susceptibility of common SSI-causing microbes to CHX over time. This provides reassurance and confidence in the worldwide guidance that CHX should remain the first-choice agent for surgical skin antisepsis.

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Background Surgical site infection (SSI) is the most common complication of surgery, increasing healthcare costs and hospital stay. Chlorhexidine (CHX) and povidone-iodine (PVI) are used for skin antisepsis, minimising SSIs. There is increasing concern of developing resistance to topical biocides, though clinical implications remain unclear. Outcomes: Determining whether the Minimum Bactericidal Concentration (MBC) for topical preparations of CHX or PVI have changed over time, in microbes relevant to SSI. Methods We included studies reporting the mean bactericidal concentration (MBC) of laboratory and clinical isolates of common microbes to CHX and PVI. Excluding non-human samples and studies using antimicrobial solvents or mixtures with other active substances. MBC was pooled in random effects meta-analyses. Change in MBC over time was explored using meta-regression. Results 79 studies were including, analysing 6218 microbes over 45 years. Most used CHX (93%), with insufficient data for meta-analysis of PVI. There was no change in MBC of CHX to Staphylococci (β 0.12 [-1.13, 1.37]; I2 99%) or Streptococci (β 0.13 [-0.35, 0.62]; I2 97%). Conclusions There is no evidence of reduced susceptibility of common SSI-causing microbes to CHX over time. Providing reassurance that the worldwide guidance that CHX should remain the first-choice agent for surgical skin antisepsis.

BackgroundSurgical site infection (SSI) is the most common complication of surgery, increasing healthcare costs and hospital stay. Topical biocides such as chlorhexidine (CHX) and povidone-iodine (PVI) are used for skin antisepsis to minimise SSIs. There is an increasing concern of developing resistance to topical biocides, however the clinical implications of this remains unclear.OutcomesThe objective of this review was to determine whether the Minimum Bactericidal Concentration (MBC) for topical preparations of CHX or PVI have changed over time, in microbes relevant to SSI.MethodsWe searched for studies which reported the mean bactericidal concentration (MBC) of laboratory and clinical isolates of common SSI causing microbes to CHX and PVI. We excluded samples derived from non-humans and studies using antimicrobial solvents or mixtures of biocides with other active substances. MBC was pooled in random effects meta-analyses and change in MBC over time was explored using meta-regression.Results79 studies were including, analysing 6218 microbes between 1976 and 2021. Most studies used CHX (93%) and there was insufficient data for meta-analysis of PVI. Enterobacteriales had the highest MBC for CHX (20 mg/L [95% CI 14, 25]; I2 95%) whilst MRSA had the lowest (3 mg/L [95% CI 1, 2]; I2 93%). There was no change in MBC of CHX to Staphylococci (β 0.12 [-1.13, 1.37]; I2 99%) or Streptococci (β 0.13 [-0.35, 0.62]; I2 97%).ConclusionsThere is no evidence of change in susceptibility of common SSI-causing microbes to CHX over time. This study provides reassurance that the worldwide guidance that CHX should remain the first-choice agent for skin asepsis prior to surgery.