Hospital-Acquired Infections 

Healthcare-associated infections (HAI) are defined as infections not present and without evidence of incubation at the time of admission to a healthcare setting. As a better reflection of the diverse healthcare settings currently available to patients, the term healthcare-associated infections replaced old ones such as nosocomial, hospital-acquired or hospital-onset infections.^[1] Within hours after admission, a patient's flora begins to acquire characteristics of the surrounding bacterial pool. Most infections that become clinically evident after 48 hours of hospitalization are considered hospital-acquired. Infections that occur after the patient is discharged from the hospital can be considered healthcare-associated if the organisms were acquired during the hospital stay.

Hospital-based programs of surveillance, prevention and control of healthcare-associated infections have been in place since the 1950s.^[2] The Study on the Efficacy of Nosocomial Infection Control Project (SENIC) from the 1970s showed nosocomial rates could be reduced by 32% if infection surveillance were coupled with appropriate infection control programs.^[3] In 2005, the National Healthcare Safety Network (NHSN) was established with the purpose of integrating and succeeding previous surveillance systems at the Centers for Disease Control and Prevention (CDC): National Nosocomial Infections Surveillance (NNIS), Dialysis Surveillance Network (DSN) and National Surveillance System for Healthcare Workers (NaSH).^[4]

Continued surveillance, along with sound infection control programs, not only lead to decreased healthcare-associated infections but also better prioritization of resources and efforts to improving medical care.

Healthcare-associated infections are of important wide-ranging concern in the medical field. They can be localized or systemic, can involve any system of the body, be associated with medical devices or blood product transfusions. This article focuses on the 3 major sites of healthcare-associated infections (ie, bloodstream infection, pneumonia, and urinary tract infection) with focus on the pediatric population.

Infectious agents causing healthcare-associated infections may come from endogenous or exogenous sources.

Endogenous sources include body sites normally inhabited by microorganisms. Examples include the nasopharynx, GI, or genitourinary tracts. Exogenous sources include those that are not part of the patient. Examples include visitors, medical personnel, equipment and the healthcare environment.

Patient-related risk factors for invasion of colonizing pathogen include severity of illness, underlying immunocompromised state and/or the length of in-patient stay.

Frequency

United States

Healthcare-associated infections are estimated to occur in 5% of all hospitalizations in the United States.^[5] In 1999, national point-prevalence surveys in pediatric intensive care units (PICU) and neonatal intensive care units (NICU) showed 11.9% of 512 patients had PICU-acquired infections, whereas 11.4% of 827 patients had NICU-acquired infections.^{[6, 7]}

International

Both developed and resource-poor countries are faced with the burden of healthcare-associated infections. In a World Health Organization (WHO) cooperative study (55 hospitals in 14 countries from four WHO regions), about 8.7% of hospitalized patients had nosocomial infections.^[8]

A 6-year surveillance study from 2002-2007 involving intensive care units (ICUs) in Latin America, Asia, Africa, and Europe, using CDC's NNIS definitions, revealed higher rates of central-line associated blood stream infections (BSI), ventilator associated pneumonias (VAP), and catheter-associated urinary tract infections than those of comparable United States ICUs.^[9] The survey also reported higher frequencies of methicillin-resistant Staphylococcus aureus (MRSA), Enterobacter species resistance to ceftriaxone, and Pseudomonas aeruginosa resistance to fluoroquinolones.

A study of bacteremia in African children found distinct differences in the microbiological causes of nosocomial bacteremia compared with community-acquired bacteremia. Nosocomical bacteremia resulted in a higher rate of morbidity and mortality and longer hospital stay. Because it is largely unrecognized in low-income countries, nosocomial infections are likely to become public health priorities as their occurrence increases.^[10]

With increasing recognition of burden from healthcare-associated infections, national surveillance systems have been developed in various countries; these have shown that nationwide healthcare-associated infection surveillance systems are effective in reducing healthcare-associated infections.^[11]

Mortality/Morbidity

Healthcare-associated infections result in excess length of stay, mortality and healthcare costs. In 2002, an estimated 1.7 million healthcare-associated infections occurred in the United States, resulting in 99,000 deaths.^[12] In March 2009, the CDC released a report estimating overall annual direct medical costs of healthcare-associated infections that ranged from $28-45 billion.^[13]

A report from the CDC showed that among the intensive care units in the United States, the year 2009 had 25,000 fewer central line-associated bloodstream infections (CLABSI) than in 2001, representing a 58% reduction. Between 2001 and 2009, an estimated 27,000 lives were saved and potential $1.8 billion cumulative excess health-care costs were prevented. Coordinated efforts from state and federal agencies, professional societies, and healthcare personnel in implementing best practices for insertion of central lines were thought to play a role in this achievement.^[14]

Sex

Healthcare-associated infections do not have a discernible sex predilection.

Age

Healthcare-associated infections occur in both adult and pediatric patients. Bloodstream infections, followed by pneumonia and urinary tract infections are the most common healthcare-associated infections in children; urinary tract infections are the most common healthcare-associated infections in adults.^[15] Among pediatric patients, children younger than 1 year, babies with extremely low birth weight (≤ 1000 g) and children in either the PICU or NICU have higher rates of healthcare-associated infections.^{[1, 6, 7, 15]}