Hospital Infection Control

Laboratory safety

How does laboratory safety impact infection control?

While laboratory safety is primarily intended to prevent morbidity due to infections in laboratory workers, laboratory-associated infections (LAIs) may furthermore impact public health, as it was shown in one of the cases with laboratory-acquired SARS, leading to secondary cases in the community, at a time the pandemic had seized. Since household-transmission of pandemic pathogens (e.g., SARS and influenza A H1N1) is well documented, the prevention of LAIs may have an individual as well public health impact.

What elements of laboratory safety are necessary for infection prevention and control?

An adequate laboratory infrastructure and an implemented bio-risk management system form the basis of prevention and control in the laboratory setting. Only a small number of LAI involved a specific incident. Mostly a non-specific association is reported such as working with a microbiological agent, being in a laboratory, being around infected animals, and non-adherence to biosafety rules. When a specific accident is described, more than 90% of all laboratory infections are caused by five (mostly preventable) type of accidents, upmost attention should be given to prevent the following: splashes & spills, needle-stick injuries, cuts, animal bites/scratches, and mouth-pipetting, see Table I.

Table I

What are the conclusions from clinical trials or meta-analyses regarding laboratory safety that guide infection control practices and policies?

The topic LAI has not been the subject of clinical trials or meta-analyses, but following the potential threat of reintroducing SARS into the community via LAIs the European Committee for Standardization (CEN) asked 72 participants from 24 countries to develop a CEN workshop agreement (CWA). The scope of the CWA was to set requirements necessary to control risks associated with the handling or storage and disposal of biological agents and toxins in laboratories and facilities.

The standard should enable organizations to:

  • Establish and maintain a biorisk management system to control or minimize risk in relation to employees and the community which could be directly or indirectly exposed to biological agents or toxins.

  • Provide assurance that the requirements are in place and implemented effectively.

  • Seek and achieve certification or verification of the biorisk management system by an independent third party.

  • Provide a framework that can be used as the basis for training and raising awareness of laboratory biosafety and laboratory biosecurity guidelines and best practices within the scientific community.

The Laboratory Biorisk Management Standard CWA 15793 is freely available on the CEN web site.

What are the consequences of ignoring laboratory safety, as it relates to infection control?

Ignoring these key concepts puts laboratory workers (LW) at risk of contracting infections from patient specimens, e.g., a laboratory-acquired infection (LAIs). LAIs are defined as all infections acquired through laboratory activities, regardless of their clinical or subclinical manifestation. The relative risk of acquiring a LAI with a specific micro-organism is a function of the virulence of the organism, the infectious dose, and the opportunity for exposure.

Spike et al., reported in 1976, the largest comprehensive review of LAIs, by analyzing 4,079 cases. Most (43%) cases were caused by bacteria, 27% by viruses, and 15% by rickettsiae. The ten most common causative agents of LAI were Brucella spp (10.8%), Coxiella burnetti (7.1%), hepatitis B virus (6.0%), Salmonella typhi (6.5%), Francisella tularensis (5.7%), Mycobacterium tuberculosis (4.5%), Blastomycesdermatitidis (4.1%), Venezuelan equine encephalitis virus (3.6%), Chlamydia psittaci (3.0%) and Coccidiodesimmitis (2.4%). This report did not include all LAI, because some laboratories do not report their LAI's and as there is no adequate surveillance system for LAI's to identify clinical, subclinical and/or asymptomatic infections.

Many of the infections in the study of Spike were reported before 1944 (e.g., 97% of the cases of brucellosis and typhoid fever), and some infections occurred predominantly in research and animal laboratories (e.g., Q fever, Venezuelan encephalitis, dermatomycoses). Harding and Byers published in 2000 a worldwide literature search, including 1.267 LAI, the top ten: Mycobacterium tuberculosis, Coxiella burnetii, Hantavirus, Arbovirus, hepatitis B virus, Brucella spp, Salmonella Spp, Shigella spp, hepatitis C virus and Cryptosporidium. Currently, gastrointestinal infections are the most common reported LAI, with Shigella being the most common micro-organism, followed by Brucella, Salmonella, and Staphylococcus aureus.

Furthermore, the risk of acquiring a specific infection seems to differ among the various types of laboratories. A threefold greater number of LAIs occurs in laboratories with fewer than 25 people. In pathology laboratories LW have a greater risk of tuberculosis, whereas in microbiological laboratories gastrointestinal infections are the most common. By ignoring the key concepts of laboratory safety, not only LW are at risk, but transmission to the general public may also occur, as was seen with SARS and the novel influenza A (H1N1) pandemic virus.

Summary of current controversies regarding laboratory safety.

Today, the concepts of laboratory safety are an integral part of laboratory quality systems and most laboratories have the technical equipment to allow safe work. Consequently, the risk of LW to contract LAIs are reduced and most certainly no longer in the range of the relatively old overviews. Still, mistakes are human, and breaks in the daily routine occur, especially when working under pressure, such as increased volumes during epidemics or highly virulent/newly emerging pathogens. Our concept of ongoing LAIs in 2012 is primarily based on case reports. Large reviews and most importantly a centralized registration system of LAIs are missing, but would be needed to get an unbiased view on the real frequency and distributions of causative pathogens.

What is the impact of laboratory safety relative to the impact of other aspects of infection control?

The aim of laboratory safety is to prevent transmission to laboratory personnel, the immediate laboratory environment (primary containment) and the environment external to the laboratory (secondary containment) and NOT to the patient as in the other field of infection control. Laboratory safety therefore consists of:

a) Technical safety (construction, ventilation, safety equipment)

b) Exploration safety (supply of personal protective equipment including gloves, alcoholic hand rub)

c) Behavioral safety (commitment and compliance of LW with the safety rules such as hand hygiene, no rings and watches, no loose hair)

General infection control measures, such as the use of gloves and good hand hygiene are an integral part of laboratory safety, and, while mainly being part of what we call behavioral safety, cannot be distinguished from laboratory safety, in general.

According to a good laboratory safety system, infectious agents are categorized into groups on the basis of their virulence (history of laboratory-acquired infections and incidents in the community), the mode of transmission in the laboratory and the environment, the infectious dose, the type and seriousness of a possible infection and the availability of preventive measures and antimicrobial treatment.

In regard to the different groups and categories, guidelines that describe appropriate containment equipment, facilities and procedures to be used by LWs were developed and referred to as biosafety levels (BSLs). Four biosafety levels are described consisting of combinations of primary and secondary barriers for particular microbiological practice. Primary barriers are defined as safety equipment against biological agents like biosafety cabinets (BSC) and enclosed containers. Secondary barriers depend on the risk of transmission of a specific agent. The design and construction of the laboratory are part of these considerations. Each BSL is designed to ensure the safety of LWs and the environment during working with specific agents. With class 1 agents, hazards are minimal; class 4 agents require maximum containment. For specific information of BSLs for infectious agents see Table II.

Table II

In a research laboratory were LWs are working with known organisms, the implementation of the BSL is rather simple. On the other hand, in the clinical microbiological laboratory where the organisms are initially an unknown, implementation of the BSLs is much more difficult. To ensure biosafety in these laboratories, safety programs should be developed and implemented. These programs should include surveillance of LAI, vaccination plans, and guidelines that restrict the duties of highly susceptible LWs (e.g., during pregnancy). Furthermore, a proper protocol for waste management should be developed, because these products may be a source of laboratory accidents. Potential infectious waste should be separated immediately after production, stored in a special bag marked with biohazard logos, and destroyed by specialized companies. Sharp materials should be collected be collected in puncture-resistant, leakage -free containers immediately after use, and should also be destroyed by specialized companies.

Overview of important clinical trials, meta-analyses, case control studies, case series, and individual case reports related to infection control and laboratory safety.

See Table III for a summary of research regarding common infection sources.

Table III

Controversies in detail.

Good laboratory safety management requires time and adaptation of the national and international guidelines to the daily clinical practice in the microbiological laboratory. For each material arriving in the laboratory, an individual risk assessment should be made and adequate safety measures should be taken. Today, health care budgets, especially those for diagnostic tests, are diminishing, while there is increasing use of fully automated systems that handle large amounts of samples with less manpower. As a consequence, laboratorium commercialization and cost savings leaves no time for pre-screening of the samples and impair individual safety measures that are deemed necessary for specific samples.

What national and international laboratory safety guidelines exist?

Centers for disease control

  • Wilson, DE, and Chosewood, LC. ed. 2007. Biosafety in microbiological and biomedical laboratories, 5th ed. CDC and NIH, Washington, DC.

  • Centers for Disease Control and Prevention. Guidelines for Biosafety Laboratory Competency. MMWR 2011;60.

European Economic Community/European Community

  • Belgium Biosafety Server

  • Checklist for the prevention of accidents in laboratories, European Agency for Safety and Health at Work.

World Health Organization

  • CEN laboratory Biorisk Management Standard CWA15793:2008

Australia / New Zealand

  • AS/NZS 2243.3:2010 Safety in laboratories. Part 3: Microbiological safety and containment

Canada

  • Laboratory Biosafety and Biosecurity, Public Health Agency of Canada.

What other consensus group statements exist, and what do key leaders advise?

The key publications, reviews and websites are used in this chapter. We do advise the review of:

  • Singh, CID, 2009: PUBMED:19480580

  • Sewell, CMR, 1995, PUBMED:7553572

  • Herwaldt, CML, 2001, PUBMED:11585780

References

Antony,, SJ, Stratton, CW, Decker, M, Mayhall, CG. "1999. Prevention of occupational acquired infections in posthospital healthcare workers". Hospital Epidemiology and Infection Control. Williams & Wilkins. pp. 1141-1158.

"Pike". 1976.

Harding, AL, Byers, KB, Fleming, DO, Hunt, DL. "Epidemiology of laboratory-associated infections". Biological safety: principles and practices. ASM press. 2000. pp. 35-54.

"Pike". 1979.

"Sulkin". 1951.

"Baron". 2008.

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