There is substantial information available covering the need for and the risk associated with jeopardized laboratory safety. However, few of these resources focus on the safety of staff members performing work during the preanalytical phases of laboratory diagnostics and testing. The members of the lab team that collect, transport, and process samples and specimens in preparation for testing are invaluable to the overall functions of the lab, and their safety is as important as that of any other laboratory employee.

Both within the laboratory and in the public domain, common bleach and disinfectant products are used with great efficacy to eliminate “99.9%” of germs, bacteria, and other harmful pathogens. However, that remaining 0.1% is more likely to cause harm within the laboratory and greater hospital walls, and this should be a concern for all practicing microbiologists.

Microbiologists working in hospital and reference laboratories encounter a wide range of microorganisms, many of which are broadly susceptible to simple soap and water. Yet there are others that invade tissue and cells, either evading or resisting antimicrobials. Some may form spores or protective mucoid coats. Others react defensively to antibiotics, causing the potential for further harm to practitioners and patients. While we may be assured that our cleaning and disinfecting procedures are effective, it is important to be vigilant for the more pernicious microbes lurking among us.

The Growth of Insusceptibility

The reality is that resistance to antibiotics and disinfecting agents began with the advent of those agents, although awareness of the degree of resistance, or that resistance was growing, has lagged far behind. Clinicians, researchers, academics, and even journalists have sought to identify and reveal both the history of resistant microorganisms, including classic works such as de Kruif’s Microbe Hunters, Postgate’s Microbes and Man, and Garrett’s The Coming Plague, among others.

In clinical settings, many practitioners simply accepted that certain microbes were resistant to certain drugs, a belief that led to the execution of Kirby-Bauer resistance/susceptibility plate studies each time the micro lab performed an identification. When penicillin was introduced, every microbe was susceptible to it, but as with penicillin, with each passing year, resistance to antibiotics and surface disinfectants grows.

During my many years as a practicing microbiologist, I did little to combat the antimicrobial resistance problem and in fact, my colleagues and I, at the time, likely contributed to its vigor through the improper use of antimicrobials, such as advocating for antibiotics for pediatric viral colds or not insisting that patients take the full course of antibiotics for a sinus infection. Today’s practitioners know a great deal more about the dangers posed by resistant microbes, and it is worthwhile to review those that persist.

Potential of Bacterial Resistance

First reported in the 1980s,1-3 linear plasmids were found to carry the genetic material to render susceptible bacteria capable of developing a carbapenemase. A plasmid—generally smaller than a virus and with a circular DNA strand—can replicate independently in a bacteria’s chromosomes. In the laboratory, plasmids are used for manipulation of genes.

First noticed in Klebsiella pneumoniae (Kp) isolates that produced a carbapenemase, it is now known that certain bacteria use more than one method of hydrolyzing an antibiotic. It has even been discovered that the plasmids carrying the gene bla_KPC have the potential of being inter-species.4 This phenomenon has now been found in Klebsiella, Escherichia coli, Pseudomonas, Acinetobacter, and likely other bacteria as well. Imagine for a moment the introduction of plasmids to the armadillo population—known carriers of Mycobacterium leprae, the causative agent of leprosy, and Yesinia pestis, the causative agent of plague?

The Efficacy of Disinfectants

Key to this discussion is the relationship between the production of carbapenemase and disinfectant resistance. If the Enterobacteriacae have developed resistance to antibiotics, is bacterial resistance to disinfectants far behind? This heralds us back to that 0.1%.

Further research into these interactions uncovered the fact that Staphylococcus aureus are able to generate proteins that pump many different toxic chemicals out of the cell. This process is similar to the human body’s mucosal discharge as a way to discharge toxins. In this sense, it does not matter which disinfectant or antibiotic we introduce to interfere with these bacteria, as there are no antibacterial effects. In fact, doing so acts like a reverse disinfectant for the bacteria’s benefit.

Another microbial development is the elaboration of enzymes that alter the disinfectant so as to render it nonlethal to the bacteria. When this development becomes widespread, it likewise does not matter what we use as a disinfectant; the microbe will neutralize the chemical through its own defense mechanisms. These discoveries and developments go hand in hand with our continued efforts to stave them off. These efforts include a range of actions, from the logistical to the physical.

Many microbiology labs switched to stainless steel countertops in the hopes of eliminating microbe buildup in the lab. However, the inevitable scratch or dent to these surfaces initiates the potential for the development of another fomite. So, while we disinfect our countertops daily using the best products and practices available to us, certain bacteria likewise gain in resistance, daily.

Innovative Disinfectants of the Future

Those of us nearing the end of our clinical careers are calling upon the current and near future leaders in clinical microbiology to apply their skills and help in the development of new and innovative disinfectants for surfaces in the laboratory.

Among the ideas being discussed is the use of heat to disinfect workbenches in the microbiology laboratory. Obviously, open flame is impractical for a number of reasons, but consider an exothermic chemical reaction that could heat the surface enough to kill numerous if not all species of bacteria. Potentially, this chemical may be used as a wipe on, or if too powerful, it could be a two-part spray applied to workbenches and which then produces sufficient heat.

Consider the number of types of chemicals used over time to disinfect surfaces. Alcohol was used until we discovered the toxic effects it had on users. This was followed by formaldehyde, the negative impacts of which are now obvious. These were in turn followed by Lysol products and Clorox bleaches and many other cleaners. All these products utilize some method to pierce the outer layer of the bacteria and interrupt its life cycle.

Other elements could be considered for use as a disinfectant, even if only theoretically at this point. Pure oxygen is a candidate, but fire risk remains as a substantial challenge to this idea. Likewise, two of the deadliest elements—sodium and chlorine—are readily available and easily stored together. But these must be individually used in their ionic state to cause harm to a microbe; storage and use of each of these in an element form is highly risky. Even in supersaturated solutions, is there enough chemical reaction to disinfect a surface? We must continue to investigate novel approaches to managing pernicious microbes and share our ideas with each other.

Conclusion

As we are aware, because there are no 100% effective microbe killers that can be deployed in accurate and precise methods, 100% of the time, this battle will continue, and it will require focused effort from practicing microbiologists and laboratorians. We know that heat can destroy a microbe by itself but must be safely applied and be safe for use within the laboratory environment. Alternatively, chemicals and compounds can enter and destroy the bacterium at a cellular level but must be controllable and also safe for use within the laboratory environment. It is my hope that the next generations of microbiologists take up the mantle and continue the good fight against particularly pernicious pathogens.

References

1. Helinski, DR. A Brief History of Plasmids. EcoSal Plus. 2022;10(1):eESP00282021.
2. Haejeong L, Juyoun S, Yeun-Jun C. Co-introduction of plasmids harbouring the carbapenemase genes, blaNDM-1 and blaOXA-232, increases fitness and virulence of bacterial host. J Biomed Sci. 2020;27:8. doi: 10.1186/s12929-019-0603-0
3. Nordmann P. Carbapenemase-producing Enterobacteriaceae: overview of a major public health challenge. Med Mal Infect. 2014;44(2):51-56. doi:org/10.1016/j.medmal.2013.11.007
4. Mari-Almirall M, Ferrando N, Jose Fernandez M, et al. Clonal spread and intra- and inter-species plasmid dissemination associated with Klebsiella pneumoniae Carbapenemase-producing Enterobacterales during a hospital outbreak in Barcelona, Spain. Front Microbiol. 2021:12:781127. doi:org/10.3389/fmicb.2021.781127

Fred Morley, MA, MT(AMT), CTC(ACHC), is a certified technical consultant in clinical laboratory operations with a specialty in microbiology applications. With more than 45 years’ experience working in, managing, and consulting for medical laboratories, Fred continues to advocate for safer and healthier working conditions for staff, and better outcomes for patients. He sits on the AMTIE scholarship committee for American Medical Technologists (AMT).

For Further Reading

Ease the Adoption of Microbiology Automation
By Aaron Odegard, MS, MLS(ASCP)CM
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A Laboratory’s New Approach to Rapid Pneumonia ID By Lolanya Rivers, MS, MLS(ASCP)CM, SMCM
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Foster Urine Culture Stewardship By Melody Boudreaux Nelson, DCLS, MS, MLS(ASCP)CM
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Using MALDI Mass Spec for Advanced Microbial Identification By Kevin M. McNabb, PhD, MBA, MT(ASCP)
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