Healthcare associated infections affect 2 million patients annually and add approximately $3.5 billion to the cost of health care. Patients may acquire infection in hospital through contact with personnel or from a nonsterile environment, or infection may develop from bacteria harbored by the patient before operation.
Hospital Personnel as a Source of Healthcare associated infection
Most nosocomially acquired bacteria are transmitted through human contact. In order to minimize transmission in hospital, rules made for behavior, dress, and hygiene should be obeyed.
Unwashed hands are by far the most frequent sources of healthcare associated infection such as pneumonia, intravenous catheter-related sepsis, burn wound infections, and even pseudomembranous colitis. In today’s atmosphere, failure to wash one’s hands between patient contacts in a hospital is essentially an unethical act.
The Operating Room as a Source of Healthcare associated infection
Any break in operative technique noted by any member of the operating team should be corrected immediately. Members of the team should not operate if they have cutaneous infections or upper respiratory or viral infections that may cause sneezing or coughing.
Scrub suits should be worn only in the operating room and not in other areas of the hospital. If they must be worn outside the operating room, they should be changed before reentering. Physicians and nurses should always wash their hands between patients. Careful hand washing should follow all contact with nosocomial infected patients. For preoperative preparation, hands and forearms up to the elbows should be scrubbed for 5 minutes with any approved agent if the surgeon has not scrubbed within the past week. Shorter scrubs are allowable between operations. Traffic and talking in the operating room should be minimized.
Though many parts of the operating environment are sterile, the operative field is not — it is merely as sterile as it can be made. Attempts to achieve a level of sterility beyond normal standards have not led to further reductions in wound infection rates. This reflects the fact that bacteria are also present in the patient, host defense mechanisms are also important determinants of nosocomial infection not affected by more aggressive attempts to achieve sterility.
Many special and expensive techniques have been devised to minimize bacterial contamination in the operating room. Ultraviolet light, laminar flow ventilation, and elaborate architectural and ventilation schemes have been advocated, but none have been definitively proved more effective than observation of current infection control guidelines and surgical discipline.
The only completely reliable methods for sterilization of surgical instruments, supplies are steam under pressure, dry heat, and ethylene oxide gas. Saturated steam at 2 atm pressure and a temperature of 120 °C destroys all vegetative bacteria, most resistant dry spores in 13 minutes, but exposure of surgical instrument packs should usually be extended to 30 minutes to allow heat and moisture to penetrate to the center of the package. Shorter times are allowable for unwrapped instruments with the vacuum-cycle or high-pressure autoclaves now widely used. Continuous dry heat at 170 °C for 1 hour sterilizes articles that cannot tolerate moist heat. If grease or oil is present on instruments, safe dry-heat sterilization requires 4 hours at 160 °C.
Gaseous ethylene oxide destroys bacteria, viruses, fungi, various spores. It is used for heat-sensitive materials, including telescopic instruments, plastic and rubber goods, sharp and delicate instruments, electrical cords, and sealed ampules. It damages certain plastics and pharmaceuticals. The technique requires a special pressurized-gas autoclave, with 12% ethylene oxide and 88% Freon-12 at 55 °C, 8 psi pressure above atmospheric pressure. Most items must be aerated in sterile packages on the shelf for 24–48 hours before use in order to rid them of the dissolved gas. Implanted plastics should be stored for 7 days before use. Ethylene oxide is toxic and represents a safety hazard unless it is used according to strict regulations.
Miscellaneous sterilization procedures include soaking in antiseptics such as 2% glutaraldehyde to remove viruses from instruments with lenses. Total sterilization by this method requires 10 hours. Chemical antiseptics are often used to clean operating room surfaces, instruments that need not be totally sterile. Other disinfectant solutions include synthetic phenolics, polybrominated salicylanilides, iodophors, alcohols, other glutaraldehyde preparations, and 6% stabilized hydrogen peroxide. These agents maintain high potency in the presence of organic matter, usually leave effective residual antibacterial activity on surfaces. They are also used to clean anesthetic equipment that cannot be sterilized. Prepackaged instruments and supplies can be sterilized with gamma radiation by manufacturers. Synthetic fabrics have now proved to be superior barriers to bacteria and less costly than the traditional cotton.
The Patient as a Source of Healthcare associated infection
When possible, preexisting infections should be treated before operation. Secretions from patients with a history of respiratory tract infections should be cultured and appropriate treatment given. The urinary tract should be cultured and specific antibiotics administered before instruments are introduced; this precaution has eliminated septic shock as a complication of urologic surgery. Dental extractions for caries are imperative prior to cardiac valve replacement.
The skin to be included in the operative field should be cleansed with antiseptic. Nonirritating agents such as benzalkonium salts should be used in or around the nose or eyes. For other skin areas, the iodophors (eg, povidone-iodine), chlorhexidine are used most commonly.
Isolation Procedures: Universal Precautions
Traditionally, patients with infection were individually isolated. Since 1985 — partly in response to the HIV epidemic—a more general kind of isolation called “universal precautions” has been substituted.
Antibiotic Prophylaxis Against Surgical Infections
Prophylactic use of antibiotics can decrease the incidence of nosocomial infections, especially surgical site infections, but at the risk of toxic and allergic reactions to the drug, drug interactions, bacterial resistance, and superinfection. The principles of antibiotic prophylaxis are simple:
Choose antibiotics effective against the expected type of nosocomial contamination.
Use antibiotics only if the risk of nosocomial infection justifies doing so.
Give antibiotics in appropriate doses, at appropriate times.
Stop dosing before the risk of side effects outweighs.
Antibiotic prophylaxis cannot and is not intended to eliminate bacteria. Use of multiple antibiotics increases the risk of drug reactions, diminishes effectiveness in the long run by promoting the emergence of resistant strains, and increases costs. Antibiotics should be given only when a significant rate of nosocomial infection is encountered without them or when the consequences of nosocomial infection would be disastrous, as with placement of vascular, cardiac, or joint prostheses.
The surgeon may be tempted to give every patient antibiotics in order to have an infection-free record, but there are several reasons why this strategy is not appropriate:
Clean wounds may become infected with organisms for which prophylactic antibiotics are ineffective.
Resistant organisms will eventually develop, creating a higher risk of infection within the hospital.
The expense and risks associated with antibiotics (eg, kidney failure, hearing loss, anaphylaxis, skin rashes, fungal infections, enterocolitis) overshadow the minimal beneficial effects of using antibiotics in clean cases. The number of antibiotic-resistant strains has been correlated with the number of kilograms of antibiotics used in any given hospital.
Control of Infection Within the Hospital
Considering the cost of hospital-associated infections, infection control is a very sound investment. Data indicate that healthcare associated infection control programs can prevent approximately one-third of nosocomial infections. Consequently, the Joint Commission on Accreditation of Healthcare Organizations requires each hospital to have an healthcare associated infection control committee with established control procedures. This multidisciplinary committee establishes rules for isolation of infected patients, for protection of hospital personnel exposed to infection, procedures for disposal of materials contaminated by bacteria, and guidelines for limiting the spread of healthcare associated infection. Infection control specialists usually record and analyze patterns of infection. Isolates of bacteria cultured from patients are routinely analyzed for potential significance to the hospital environment. Attempts are made to determine the source of “epidemics.” These efforts are coordinated at the national level by the CDC to monitor and report healthcare associated infection trends. These data are then used to generate recommendations and guidelines to improve outcomes.