1. Contact with a colonized person, an actively infected person, a host, or a fomite is the most frequent route of transmission in the OR.

2. Body fluids (blood, urine, CSF) are a method of transmission that depends on access to a mucosal surface or a break in the integrity of the skin barrier.

3. Droplet transmission is the transfer of infectious particles via suspension in large fluid droplets such as those released during coughing or sneezing which travel short distances.

4. Airborne transmission is similar to droplet transmission with the exception that the particles are small enough to remain suspended in air and travel in air currents.

B. Standard or Universal precautions constitute a minimum of acceptable guidelines that should be used for all patient populations regardless of infectious status.

1. Hand hygiene has consistently been shown to be the single most important method for preventing nosocomial infections. Basic hand hygiene requires that alcohol-based hand rub be used before and after any patient contact including any contact with equipment in the immediate vicinity of the patient.

2. Personal protective gear including gloves, gowns, masks, eye protection, and face shields should be readily available. Gloves should be used any time there is potential for contact with body fluids and additional protective gear should be used when indicated based on precaution requirements.

3. Appropriate OR attire to prevent infectious spread includes clean scrubs that have not been worn outside of the OR, a cap or bonnet that covers all hair including beards, a mask, and either OR dedicated closed toed shoes or shoe covers over general use closed toed shoes.

C. Specific precautions are necessary based on specific pathogens and their mode of transmission.

1. Contact precautions are applied to patients with pathogens that can be transmitted by direct or indirect contact. The most frequently encountered organisms are methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). Routine screening via rectal (VRE) and nasal (MRSA) swabs has increased the identification of colonized patients, thus increasing the number of patients on contact precautions.

a. Gloves and gown should be donned prior to entering and removed upon exiting the patient room.

b. Alcohol based hand cleanser or hand washing should occur prior to gowning and gloving and immediately following gown and glove removal.

c. During transportation, gowns and gloves should only be worn if providing direct patient care necessitating contact with the patient.

d. Medical records should be kept outside of the patient room and transported in a plastic bag.

e. Removal of contact precautions is hospital specific and organism specific. Typical standards include cessation of antibiotics for at least 48 hours, negative cultures from the infected site if applicable and three negative cultures on different dates from the common site of colonization (MRSA—nasal, VRE—rectal).

2. Contact precautions plus is for patients with known or suspected infection with spore forming or alcohol-resistant organisms that can be transmitted by direct or indirect contact. The most frequently encountered is Clostridium difficile. In addition to standard contact precautions, hands must be washed with water and soap after glove and gown removal. These precautions may be discontinued after completion of an appropriate antibiotic course and resolution of symptoms.

3. Strict contact precautions are for patients with infection or colonization with S. aureus that has reduced sensitivity to vancomycin (vancomycin intermediate sensitivity [VISA]) or vancomycin-resistant Staphylococcus aureus (VRSA). In addition to contact precautions plus, patients should have dedicated staff assigned to their care, and patients should only be transported for essential purposes. In order to discharge the patient, transfer the patient to another facility, or discontinue strict contact precautions, the local health department must be contacted.

4. Droplet precautions are for patients with known or suspected infection with organisms that are transmissible via large respiratory droplets. The most frequently encountered organisms/diseases include meningococcal meningitis, Mycoplasma pneumonia, and influenza.

a. Disposable surgical masks should be worn by providers when within 3 feet of the patient and should be disposed of immediately after exiting the room. Hand hygiene should be completed after disposing of the mask.

b. Transportation of the patient requires the patient to wear a surgical mask.

5. Airborne precautions are for patients with known or suspected infection with organisms that may remain suspended in the air and be dispersed by air currents. The most frequently encountered organisms include pulmonary tuberculosis and Varicella.

a. N95 respirators should be worn whenever in the patient’s room. These are specialized masks that require fit testing and training prior to use.

b. Negative pressure isolation rooms are required and doors should remain closed.

c. Transportation of the patient requires the patient to wear a surgical mask and those providing direct care to wear an N95 respirator.

1. Bactericidal cleaning agents should be used between all cases on the anesthesia machine, monitors, and work station.

2. Clean workstation standards at MGH mandate that any item that has touched the anesthesia machine tray will be discarded between cases to prevent cross contamination.

3. Sterilization of reusable equipment between uses is necessary (i.e., laryngoscopes, reusable laryngeal mask airways (LMAs), bronchoscopes, reusable stylets).

4. Bacterial contamination of the anesthesia machine and the possibility of cross contamination between patients is a controversial topic. Available data have shown no significant difference in postoperative pulmonary infection rate between reusable circuits that are appropriately cleaned and disposable circuits. The addition of a bacterial filter does not prevent infectious transmission. The high oxygen content, metallic ions, and the shifts in temperature and humidity present within the machine are bactericidal.

5. Air exchanges in the OR should occur at a minimum of 15 times per hour, and the OR should be maintained at a positive pressure relative to surrounding areas with few exceptions (i.e., airborne precaution patient).

1. Peripheral intravenous lines should be placed after cleaning of the insertion site with an approved cleaning solution (at MGH, these include 70% isopropyl alcohol, povidone iodine, or 2% chlorhexidine/70% isopropyl alcohol) and covered with a transparent occlusive dressing.

2. Strict sterile technique including site cleaning, drapes, mask, and sterile gloves should be used for other invasive procedures including epidural placement, spinals, arterial lines, and peripheral nerve blocks.

3. Central venous catheters (CVC) are a major source of potentially avoidable nosocomial infections. The most common sites of venous cannulation are the femoral, internal jugular, and subclavian veins. It was traditionally taught that femoral lines were the “dirtiest,” and subclavian lines the “cleanest,” but recent studies indicate that sterile technique in placement and daily assessment is more important than site choice. Central line-associated blood stream infection (CLABSI) is a source of major morbidity and health care expenditure. Causes include infection from skin flora at the site, contamination of infusions or catheter hubs, and seeding from distant sites. Emergency insertion, long duration in situ, use for total parenteral nutrition, and an increased number of lumens heighten the risk of CLABSI. The most common pathogens
are bacteria including Staphylococcus and Streptococcus spp. as well as Candida spp.

a. Protocols for placement and daily care decrease CLABSI. Use of a checklist and dedicated monitoring personnel during placement ensures strict sterile technique including full draping of the patient, aseptic technique (hand prep, site prep, sterile gown and gloves, mask), and appropriate dressing. Use of a daily care checklist ensures site skin integrity, maintenance of a transparent occlusive dressing, and ongoing evaluation for necessity of central access as well as appropriateness of removal. Routine replacement of CVC has not shown any clinical benefit.

b. Diagnosis of CLABSI is based on clinical manifestations, ranging from localized signs of infection to septic shock, combined with laboratory culture data. Blood, sputum, and urine cultures as well as wound cultures if applicable should be obtained prior to antibiotic initiation. If further clarity is required, simultaneous quantitative blood cultures, one from a peripheral site and one from the CVC, should be obtained. A 5- to 10-fold higher colony count on the culture from the CVC supports the diagnosis of CLABSI.

c. Treatment of CLABSI. The CVC should be removed and replaced at a new site. Changing the catheter over a guide wire is increasingly considered a suboptimal management technique. Empiric antibiotic coverage is appropriate with narrowing of coverage as soon as Gram stain and culture data allows. Typical antibiotic courses for uncomplicated CLABSI are 7 to 14 days, but longer courses may be indicated for fungal infections and immunocompromised hosts.

4. Aspiration pneumonia is a potentially lethal infectious anesthetic complication as a result of aspiration of oropharyngeal or gastric contents that can occur at any point when the airway is not secured.

a. Aspiration pneumonia indicates an actual infectious etiology while aspiration pneumonitis reflects a noninfectious chemical pneumonitis. Differentiation between the two can be challenging and as such antibiotic therapy should not be reflexively initiated for all aspiration events.

b. Risk factors for aspiration include emergency surgery, insufficient time spent NPO prior to induction, pregnancy, gastroparesis or other functional obstruction, bowel obstruction, and severe gastroesophageal reflux.

c. Risk factors for aspiration pneumonia include large volume of aspiration, aspiration of low pH content matter, aspiration of particulate matter, immunocompromised status, and known colonization of secretions.

d. Treatment of aspiration pneumonia should target the most frequent bacteria encountered: S. aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and anaerobes. Broad spectrum antibiotics may be indicated if pneumonitis has not improved in the first 48 hours. Narrowing of antibiotics should be accomplished as soon as possible based on respiratory Gram stain and culture.

5. Transfusion-related infections have been minimized by using increasingly stringent testing protocols for all donated blood products. Use of appropriate transfusion thresholds can decrease the frequency and quantity of transfusion to additionally decrease related infection rates. (Table 7.1)