Efficacy of preoperative antimicrobial skin preparation solutions on biofilm bacteria

AORN Journal, March, 2005 by Daryl S. Paulson

The article "Efficacy of preoperative antimicrobial skin preparation solutions on biofilm bacteria" is the basis for this AORN Journal independent study. The behavioral objectives and examination for this program were prepared by Rebecca Holm, RN, MSN, CNOR, clinical editor, with consultation from Susan Bakewell RN, MS, BC, education program professional, Center for Perioperative Education.

Participants receive feedback on incorrect answers. Each applicant who successfully completes this study will receive a certificate of completion. The deadline for submitting this study is March 31, 2008.

Complete the examination answer sheet and learner evaluation found on pages 505-506 and mail with appropriate fee to

AORN Customer Service

c/o Home Study Program

2170 S Parker Rd, Suite 300

Denver, CO 80231-5711

BEHAVIORAL OBJECTIVES

After reading and studying the article on biofilms and the efficacy of antimicrobial skin preparation solutions on biofilm bacteria, nurses will be able to

1. describe how biofilm matrices develop,

2. identify at least three implanted devices at risk for being infected with biofilms that are commonly encountered by perioperative nurses,

3. explain how an evaluation was performed to determine efficacy of topical skin antiseptics against biofilm infections, and

4. discuss recommendations for preventing development of biofilm matrices.

This program meets criteria for CNOR and CRNFA recertification, as well as other continuing education requirements.

A minimum score of 70% on the multiple-choice examination is necessary to earn 2.4 contact hours for this independent study.

Purpose/Goal: To educate perioperative nurses about biofilms and the effect of antimicrobial skin preparation solutions on biofilm bacteria.

Until recently, perioperative professionals were taught that microbial infections (eg, bacterial, viral, fungal) were caused by free-moving, individual microorganisms or small isolated groups of microorganisms. Microorganisms causing infections

* entered the body via a wound or by direct invasion;

* spread through the body;

* multiplied in the body;

* evaded immunological defenses (ie, T lymphocyte, B lymphocyte, and phagocytic activity); and

* were shed from the body to infect new hosts. (1)

Although it is true that in acute infections, bacteria generally are found in a free-floating (ie, planktonic) form, if bacteria (ie, prokaryotes) establish a presence of any duration in the body, they generally form a highly complex, self-regulating, bacterial community known as a biofilm matrix. (2) Bacterial biofilm complexes cause challenging infections that generally are both difficult and expensive to treat and manage. Terms relevant to biofilm bacteria are defined in Table 1.

Through a process termed "quorum-sensing," bacteria in a biofilm matrix can chemically communicate system-level needs for the well-being of the entire biofilm community. Quorum-sensing between bacteria enables a biofilm community to induce or repress specific gene expressions regulating such activities as

* cell division,

* metabolic rates,

* production of virulence factors,

* plasmid transfer for antibiotic resistance, and

* release of planktonic bacteria from the biofilm. (3-5)

Biofilm infections often begin during surgical procedures, such as insertion of vascular catheter lines, pacemakers, heart valves, permanent biomaterials for repair of aneurysms, or prosthetic joint replacements. Other medical procedures associated with biofilm establishment are intratracheal intubation needed for ventilators and protracted use of indwelling urinary catheters. (6) It is important for perioperative staff members to recognize that implantation of devices or biomaterials may lead to the formation of biofilms, which increases the risk of difficult-to-treat infections in postoperative patients.

BIOFILM GENESIS

To form a clinically significant biofilm, bacteria must attach to tissue or an inanimate surface (eg, titanium, stainless steel, polytetrafluoroethylene, polyester fiber) in a patient's body and then attract and attach to other bacterial cells. (4-7) Typically, direct attachment of bacteria to tissue elicits such a strong immunological response (eg, high fever, malaise) that it becomes apparent, and patients are treated immediately, according to standard protocols, before a biofilm is able to develop. In comparison, implanted biomaterials, prosthetics, and devices have inanimate surfaces. Bacteria adhering to these inanimate surfaces do not elicit an immune response. The lack of an immune response results in patients not being treated for infection; thus, normal skin bacterial residents (eg, Staphylococcus epidermidis) attaching to implanted materials can lead to the development of a biofilm.

Bacterial attachment to inanimate surfaces generally requires that a surface be conditioned by organic deposits, such as collagen, laminin, fibrin, and fibrinogen. The bacterial cells and organic deposits are mutually attracted via noncovalent forces, including vander Waal's forces and hydrophobic interactions. (7-9) Bacteria with receptor sites for these organic compounds can attach directly to the compounds by primary adhesion (Figure 1), divide, and produce an exopolysaccharide biofilm matrix. This establishes a bacterial presence that is protected from the body's natural immunological surveillance, including phagocytosis and antibiotic treatments. (7)