Chlorhexidine gluconate (CHG) Resistance in Bacteria—Should I Be Concerned?

Author: Caitlin Stowe MPH, CPH, CIC,

Categories: Skin / Device Antisepsis December 1, 2016
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A recent article entitled Mechanisms of increased resistance to chlorhexidine and cross-resistance to colistin following exposure of Klebsiella pneumoniae clinical isolates to chlorhexidine published in the Antimicrobial Agents and Chemotherapy journal showed how researchers induced resistance to chlorhexidine (CHG) in Klebsiella pneumoniae, and identified cross-resistance to the antibiotic, colistin—marking the first time that any bacteria was shown to exhibit resistance to CHG.

[If the resistant Klebsiella from this study was exposed to PDI’s Prevantics® antiseptics products, the bacteria would have been killed by the CHG level. Read further to see why.]

Traditionally, CHG has been used for skin antisepsis and disinfection, usually mixed with at least 70% isopropyl alcohol to provide a “1,2 punch” to kill microorganisms on a surface. CHG provides long-lasting bacterial growth inhibition whereas the alcohol provides almost immediate microorganism kill on a surface.

In this particular study, the researchers exposed the bacteria to extremely low levels of CHG. If the initial low level of CHG exposure did not kill the bacteria, then the concentration of CHG was doubled, and the bacteria was exposed again. This process continued until the researchers were able to isolate several Klebsiella strains that showed resistance to CHG. The minimum inhibitory concentration (MIC) that these resistant strains showed to CHG ranged from 0.0256-0.0512% CHG, the absolute least [amount of] CHG concentration that would kill the bacteria.

This lends itself to the key question: Should I be concerned?

In short, no (not for PDI products).

There are a couple of reasons for this. First, the percent of CHG that the Klebsiella showed resistance to is much less than the concentration found in antisepsis and disinfection solutions. In fact, it’s 61 times less than the concentration found inPDI’sPrevantics products, which contain 3.15% CHG. So, if the resistant Klebsiella from this study was exposed to our products, the bacteria would be killed by the CHG. Second, PDI products also contain 70% isopropyl alcohol, which greatly enhances the kill effect of the antiseptic solution. Additionally, this study was done in the laboratory setting, so there’s no evidence that this mutation would happen in a clinical setting with patients.

While the particular strains of Klebsiella showed increased resistance to colistin, often considered the last line of antimicrobial defense for certain multi-drug resistant organisms, there’s no need to ring the alarm quite yet. The researchers evaluated the susceptibility of the resistant Klebsiella to multiple antiseptics and antibiotics, and there was no increased resistance to anything other than colistin. So while the increased resistance to colistin is concerning, there are still other drugs the Klebsiella was susceptible to.

Additionally, this study showed something we already know—bacteria can efficiently mutate to help increase chances for survival. In this particular example, the mutation that helped the bacteria survive exposure to CHG also caused resistance to colistin. This study helps highlight the need for continued antibiotic stewardship and proper use of antiseptic and disinfection products. Through prudent use of antibiotics as well as ensuring that proper technique is followed for skin antisepsis, we can prevent this from occurring outside of the lab.


Matthew E Wand, Lucy J Bock, Laura C Bonney, J Mark Sutton. Mechanisms of increased resistance to chlorhexidine and cross-resistance to colistin following exposure of Klebsiella pneumoniae clinical isolates to chlorhexidine. Antimicrobial Agents and Chemotherapy, 2016; AAC.01162-16 DOI: 10.1128/AAC.01162-16

Author

Caitlin Stowe MPH, CPH, CIC, CPHQ, VA-BC
Caitlin Stowe PDI Clinical Research Manager Clinical Affairs Research Manager, PDI

Profile

Caitlin started her career at the early age of 12, working in her parents’ medical practice. During graduate school, she got the chance to shadow an infection preventionist, and was hooked. Caitlin has practiced in a variety of infection prevention roles and settings since 2009.

Caitlin joined PDI in 2016 as a clinical science liaison (CSL), and provided clinical expertise to customers in the Midwest region of the country. She was promoted in 2019 to PDI’s first Clinical Affairs Research Manager.

Currently, Caitlin manages the clinical evidence portfolio for all post-market PDI products.

Contact

Phone: 615-920-6603

Company Website pdihc.com

Email: Caitlin.Stowe@pdihc.com

Hobbies

Spending time with my family
Reading
Pilates
Hiking

Education

Nova Southeastern University
Doctor of Philosophy in Health Science – In progress

University of South Florida
Master in Public Health in Global Communicable Disease

University of South Florida
Graduate Certificate in Infection Control

University of Central Florida
Bachelor of Science in Liberal Studies

Certification
Certification in Public Health (NBPH) – CPH
Certification Board of Infection Control (CBIC) – CIC
Certified Professional in Healthcare Quality (NAHQ) – CPHQ
Certification in Vascular Access (VACC) – VA-BC

Why I love what I do

I have always loved learning, especially about science. When I found infection prevention, the combination of statistics, disease transmission, and education sounded like the perfect career to me. I have enjoyed every step of my infection prevention journey, and transitioning to industry and then research, has really allowed me to evolve my skill set. I love being able to help our customers by acting as a resource they can use when they have questions.

Areas of Expertise

Research
Epidemiology
Emerging Pathogens
Infection surveillance technology
Education

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