Nosocomial infections are the single most common adverse event experienced by hospitalized children and adults. A recent multicenter survey found that 6% of patients develop nosocomial infections during admission to an acute care hospital.¹ A point prevalence study performed in 30 pediatric facilities in Canada found an 8.7% prevalence of healthcare-associated infections and the prevalence was greatest for patients in intensive care units and oncology wards.²

Healthcare-associated infections increase morbidity, extend hospital stays, and raise hospital charges, and they are also associated with substantial increases of in-hospital mortality. An analysis of discharge data from more than 5 million pediatric hospitalizations revealed that postoperative sepsis and infection as a result of medical care were common events among hospitalized children and had a remarkable impact on length of stay and hospital costs.³ These findings persisted even after adjustment for patient and hospital characteristics (Table 5-1). Additionally, patients with a healthcare-associated infection were more likely to require the use of isolation precautions and antimicrobial therapy.²

Thus the risk of healthcare-associated infections is significant, and the consequences are great. It is critical that all members of a healthcare team remain vigilant in order to prevent their patients from acquiring nosocomial infections during hospitalization.

To prevent nosocomial infections, healthcare providers must understand how organisms are transmitted, both between individuals and from the environment or an inanimate object to a patient, how and when colonizing organisms (often referred to as commensal organisms) can become pathogenic, and how host and environmental factors modify the risk of nosocomial infection.

HOW ORGANISMS ARE TRANSMITTED

Three basic mechanisms explain how most microorganisms are transmitted from one person to another: contact, either direct or indirect; droplet transmission; and airborne spread.

Contact is the most common route by which the vast majority of bacteria and viruses are spread among patients and healthcare workers. Viruses, such as respiratory syncytial virus (RSV), and bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), are typically spread directly from one person to another, particularly when infected or colonized children play together in hospital playrooms. Hands, particularly those of healthcare workers, are another critical method by which potentially pathogenic organisms spread between patients. Indirect contact or fomite transmission is yet another common way that organisms, especially those capable of surviving for long periods on inanimate objects, can spread within the hospital setting. Because many viruses such as RSV can survive in dried secretions for hours, commonly touched items, like bed rails, can become reservoirs for transmission in the absence of thorough disinfection between patients.

Respiratory droplets are responsible for the transmission of many common pediatric pathogens, including influenza viruses. Large respiratory droplets that contain viral particles are expelled from the nose and mouth during coughing, sneezing, and talking or during procedures such as suctioning, bronchoscopy, and cough induction by chest physiotherapy. These droplets can travel 3 to 6 feet in the air before settling. Transmission typically occurs when droplets come into contact with mucous membranes. Thus, face-to-face encounters with infected individuals allow the transmission of many viral pathogens in the absence of direct physical contact. Inadvertent inoculation of the conjunctival mucosa has been shown to be an important route of transmission for viruses.

Airborne transmission occurs by the dissemination of droplet nuclei (small particles ≤ 5 μm), which are evaporated droplets that contain infectious microorganisms. These droplet nuclei can remain suspended in the air for long periods, become airborne, and travel significant distances from their point of origin. Organisms such as Mycobacterium tuberculosis (MTB), varicella virus, and measles virus can survive desiccation and exist as droplet nuclei. The outbreak potential for these organisms is great.

HAND HYGIENE AND STANDARD PRECAUTIONS

Hand hygiene is the most critical element in the prevention of nosocomial infections. Sadly, studies have repeatedly shown that healthcare workers frequently fail to clean their hands at the appropriate times while providing patient care.⁵ Thus, healthcare workers are one of the most common sources of transmission of infection among patients. Hands should be washed with soap and water before and after eating, after using the bathroom, and when they are visibly soiled.⁴ At all other times, healthcare providers should use alcohol-based hand rubs. The World Health Organization specifies five opportunities for hand hygiene that may arise in clinical care: (1) before contact with the patient; (2) before an aseptic procedure is performed; (3) after blood and body fluid exposure; (4) after contact with the patient; and (5) after contact with the patient’s environment. One of the most common errors made by clinicians is failing to perform hand hygiene before donning and after removing gloves. Alcohol hand rubs are more effective than soap and water at reducing microbial colonization of the hands.⁶

In addition to performing hand hygiene before and after every patient contact, all healthcare workers should observe standard precautions with every patient. These are transmission-based precautions designed to protect healthcare workers from exposure to any known or unknown pathogens that might be transmitted by contact with blood or body fluids. Critical elements of standard precautions include: (1) hand hygiene; (2) use of gloves when touching blood, body fluids, mucous membranes, or nonintact skin; and (3) mask, gown, and eye protection during procedures that might result in sprays of blood or body fluids.

TRANSMISSION-BASED PRECAUTIONS AND THE USE OF PERSONAL PROTECTIVE EQUIPMENT

In addition to standard precautions, transmission-based precautions markedly reduce the risk of spread of many common agents of healthcare-associated infections (Table 5-2).⁷ Because many community-acquired pediatric pathogens are easily spread in inpatient units, the use of transmission-based precautions is especially important for pediatric facilities.