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By Kelly M. Pyrek
The opportunities for bacterial cross-contamination arenumerous in the healthcare environment. This article will highlight both theexpected and unexpected opportunities for cross contamination in a hospital'skitchen, operating room and central sterile department.
IN THE KITCHEN
Many cases of foodborne illness are caused by the consumption of ready-to-eatfoods contaminated by poor handling techniques and the cross contaminationbetween raw and finished food products. Seventy-five million cases of foodborneillness occur each year in the United States; of these cases, 325,000hospitalizations and 5,000 deaths resulted according to a 1999 study by theCenters for Disease Control and Prevention (CDC). These statistics areparticularly frightening, considering that food service in hospitals impacts alarge group of immunosuppressed individuals who are open to opportunisticpathogens.
A team of researchers at the North Carolina State University and ResearchTriangle Institute decided to estimate the degree of risk to human health posedby cross contamination during food preparation and conducted an exposureassessment to address the likelihood and routes of transmitting Salmonella andCampylobacter jejuni during food handling.
Various food-handling scenarios were designed to model cross contaminationfrom raw to cooked foods via contaminated hands, countertops, cutting boards anddishcloths, and laboratory investigations provided data concerning the transferrate of pathogens. Simulations estimated that in most cases, less than 1 percentof pathogens were transmitted during food handling. Taking into account pathogensurvival rates on surfaces and marginal cleaning efforts during foodpreparation, an initial Salmonella level of 100 CFU/ml in meat exudates wouldresult in a mean level of 0.056 CFU/g for food contaminated through contact withcontaminated hands, countertops and dishcloths. The researchers say that whilethis level of contamination may seem small, the levels of contamination may besignificantly higher when considering cases of "gross mishandling"during food preparation. The study shows that exposure levels are greatlyinfluenced by survival and transfer rates during pathogen transmission.
When inservicing kitchen workers about cross contamination, infection controlpractitioners (ICPs) may want to consider addressing the potential hazard of"wet-nesting" of foodservice dishware, explored by researcher DanielleHautenne-Dekay, a clinical dietitian at Swedish Medical Center in Ballard,Wash., and her team in the August 2001 issue of the Journal of the AmericanDietetic Association.
According to The American Dietetic Association (ADA), changes in demographicsand lifestyles have contributed to the increase in foodborne illness observedduring the last 20 years. Americans now consume more meals from commercialfoodservice establishments -- including healthcare facilities -- where highemployee turnover, an unskilled foodservice labor force and increased demandpresent more opportunity for cross contamination of food items than ever before.
One aspect of food safety, according to the ADA, is the proper sanitation ofdishware on which food is served. The 1999 Food and Drug Administration (FDA)Food Code specifies air-drying of all dishware as an important step inpreventing bacterial growth on food-contact surfaces. The code states,"Items must be allowed to drain and to air-dry before being stacked orstored. Stacking wet items such as pans prevents them from drying and may allowan environment where microorganisms can begin to grow." This stacking ofdishes before being completely air-dried is called wet-nesting.
Kitchen managers evaluate their operations based on the FDA Food Code;however, no scientific evidence implicating wet-nesting as a food safety concernhas been gathered. A study at the Veterans Affairs Medical Center in Portland,Ore., was conducted to determine if wet-nesting of serving plates increased theincidence of foodborne illness.
In the study, samples were taken from 100 randomly selected breakfast servingplates returned to the patient foodservice kitchen. Cultures were taken fromsoiled plates after excess waste had been scraped away. A template of the 91/8-in serving plates was made with a 3x3-inch square cut out of the center toensure consistency in the areas swabbed.
Sterile cotton-tipped swabs were moistened with 0.85 percent saline solutionimmediately before touching the soiled serving plates. A total of 40 zigzagstokes were made, starting in the upper left-hand corner and moving to thebottom right. The swab was immediately placed in a test tube containing 2 mLtryptic soy broth obtained from the hospital's microbiology laboratory, sealedand taken immediately to the microbiology laboratory. After vortex mixing for 10seconds, 0.1 mL broth from each sample was spread evenly over individual bloodagar plates. The plates were incubated for 24 hours; following incubation,bacterial growth was determined by visual inspection for colony-forming units. Acount was then made of the number of blood agar plates having colony-formingunits. The lower level of detection with this method is 10 colony-forming unitsper milliliter of broth.
The sanitizing equipment used in the study was a dishwashing machine with alltemperature requirements met during all cycles (prerinse 160 degrees to 180degrees F, wash 150 degrees to 170 degrees F and final rinse 180 degrees to 195degrees F). Fifty of the 100 sample plates were run through the dishwashingmachine and retrieved after completing the full cycle. The plates wereimmediately placed in stacks of 10 plates each. In between each plate, 5 mLsterile water was added to ensure a moist environment. These wet-nested servingplates were allowed to sit for 24 hours and were swabbed again using thepreviously stated method. The remaining 50 soiled plates were run through thedishwashing cycle but were allowed to air-dry separately for 24 hours placedvertically in a dish rack in a dry, low traffic area of the kitchen. Theseclean, air-dried plates were swabbed and plated using the previously statedmethods.
The original tryptic soy broth samples from the wet-nested and air-driedplates were incubated for a second 24-hour period to allow additional time forbacterial growth.
Even though 95 of 100 plates showed bacterial contamination beforedishwashing, no significant difference in bacterial growth was found betweenair-dried and wet-nested plates in the first 24 hours, but a significantdifference was found after 48 hours.
Testing for specific microorganisms was not completed because of financialconstraints; however, researchers presumed the microbial load consisted ofnormal mouth flora such as Streptococci and Staphylococci.
According to the author, "The data show that wet-nesting of dishware, ifheld for long periods before reuse, may be of concern in specific foodserviceoperations, particularly in hospital and other foodservice operations thatprovide meals for immunocompromised persons. This suggests the need for furtherstudy on the range of identifiable microorganisms that can survive currentdishwashing temperature/chemical decontamination standards. Additional bacteriamay survive when dishware is washed either by hand or by a less-effectivedishwashing machine or when dishes are held for extended periods of time.Wet-nesting of dishes does not appear to pose a serious risk for bacterialcontamination of food when dishware is sanitized with proper equipment andchemicals at appropriate temperatures. However, wet-nesting may pose a threat ifdishes are allowed to sit for longer than 24 hours before being used."
IN THE PATIENT ROOM
The key to minimizing the spread of infection is to decrease opportunitiesfor cross contamination, especially in patient rooms where direct care is given.Infection control experts agree that handwashing is the most critical procedurefor preventing the spread of infection. According to the Association forProfessionals in Infection Control and Epidemiology (APIC), hands should bewashed after contact with body fluids, soiled linen, waste or contaminatedequipment; after removing gloves; before and after performing clean or sterileprocedures; between tasks on different body parts of the same resident; betweenresident contacts; and before and after eating, drinking, smoking, applyingcosmetics or preparing food.
IN THE PHYSICAL PLANT
The CDC states that linens should be handled as little as possible and withminimum agitation. Sheets should be rolled when removed from the bed to reducetransmitting airborne bacteria. Soiled linens should be bagged to containbacteria and then transported, preferably in covered containers, which should becleaned on a regular basis. Sorting soiled linen prior to washing minimizesexposure of facility and laundry personnel to potentially infectious material. Ahot-cycle wash should be used, and clean linens should be stored in coveredcontainers or shelves.
It is recommended that environmental services personnel monitor environmentalcleanliness by doing rounds with a checklist for each area of the facility. APICsuggests the following points to keep in mind when cleaning resident and publicareas of hospitals:
Infectious waste, categorized as items contaminated with blood and otherpotentially infectious body fluids, should be contained in leak-proof bags orcontainers that will resist ripping, tearing or bursting during handling.Containers of infectious waste should be color-coded or labeled, large enough tocontain various forms of waste and closed prior to removal to prevent spilling.Disposable sharp items should be packaged or maintained in puncture-resistant,leak-proof containers that are labeled with a red color or "biohazard"label.
A number of factors can contribute to cross contamination in the hospitalbuilding itself, according to Alvin Chapital, healthcare market segment managerfor Kimberly-Clark. Walls, floors, furniture and countertops should be selectedfor ease of maintenance, cleaning and disinfection. In bathroom areas, no-touchproducts can reduce the transmission of bacteria, and faucets, towel, tissue andsoap dispensers, light switches and toilet flushing devices can be purchasedwith an electronic sensor that detects motion and activates automatically.
IN THE STERILE PROCESSING DEPARTMENT
There has been no shortage of news headlines announcing a large number ofinfections that have been traced to improperly cleaned, disinfected andsterilized surgical instruments and endoscopes. Bioburden allowed to dry andremain on these instruments will endanger the health and safety of the patientwho is operated on next. To help operating room personnel avoid surgical siteinfections, central sterile/sterile processing personnel must understand themechanisms of cross contamination as they apply to this department. Debris leftin the lumens and channels of an endoscope used on one patient will introducepathogens to the next patient unless the chain of infection is broken and thesurgical instrument is prepped correctly, following the hospital's guidelinesfor cleaning, disinfection, sterilization, assembly and wrapping.
When the case cart is delivered to the operating room, its access byhealthcare workers (HCWs) should be limited in order to protect packageintegrity and prevent cross contamination. Every time a package is handled,contaminants from a HCWs' hands that were picked up from other animate orinanimate objects can be transmitted to the package surface, allowing pathogensto enter through microscopic holes or tears in the wrapping material.
IN THE OPERATING ROOM
Getting the OR ready is a prime opportunity for cross contamination ifpersonnel are not careful in opening sterile supplies, setting up the sterilefield with instruments for the surgical procedure and preparing the patient forsurgery. Following aseptic principles and techniques can create and maintain aclean surgical environment, according to Cathy Osman, RN, BS, CNOR. She explainsthat key infection control measures in the OR must focus on preventing crosscontamination and ensure a smooth traffic flow of entrance to exit or clean todirty areas in a series of clearly delineated unrestricted and restricted areas.
"Good traffic control practices protect personnel, patients, suppliesand equipment from potential sources of cross contamination," she says.
The unrestricted area usually includes entrances and exits to the surgicalsuite, as well as patient-holding areas, post-anesthesia recovery units,supply-receiving areas, offices and locker rooms. The restricted area includesthe OR and adjacent substerile areas, and surgical attire must be worn bypersonnel. Masks are required when sterile supplies are open or when scrubbedpersonnel are present, according to practices recommended by the Association ofperiOperative Registered Nurses (AORN). Supplies and equipment, not justsurgical personnel, must also follow designated traffic patterns so as not toundermine surgical environmental controls.