eMedicine Specialties > Pediatrics: General Medicine > Infectious Disease
Hospital-Acquired Infections
Updated: Jul 20, 2010
Introduction
Background
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.
Pathophysiology
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.
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.10
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.11 In March 2009, the CDC released a report estimating overall annual direct medical costs of healthcare-associated infections that ranged from $28-45 billion.12
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.13 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.1,6,7,13
Clinical
History
Healthcare-associated infections are most commonly caused by viral, bacterial, and fungal pathogens. These pathogens should be investigated in all febrile patients who are admitted for a nonfebrile illness or those who develop clinical deterioration unexplained by the initial diagnosis.
Most patients who have healthcare-associated infections caused by bacterial and fungal pathogens have a predisposition to infection caused by invasive supportive measures such as endotracheal intubation and the placement of intravascular lines and urinary catheters. Ninety-one percent of bloodstream infections were in patients with central intravenous lines (CVL), 95% of pneumonia cases were in patients under going mechanical ventilation, and 77% of urinary tract infections were in patients with urinary tract catheters.13
Risk factors for the development of catheter-associated bloodstream infections in neonates include catheter hub colonization, exit site colonization, catheter insertion after the first week of life, duration of parenteral nutrition, and extremely low birth weight (<1000 g) at the time of catheter insertion.14 In patients in the PICU risks, for catheter-associated bloodstream infections increase with neutropenia, prolonged catheter dwell time (>7 d), use of percutaneously placed CVL (higher than tunneled or implanted devices), and frequent manipulation of lines.15
Candida spp are increasingly important pathogens in the NICU. Risk factors for the development of candidemia in neonates include gestational age less than 32 weeks, 5-min Apgar scores of less than 5, shock, disseminated intravascular coagulopathy, prior use of intralipids, parenteral nutrition administration, CVL use, H2 blocker administration, intubation, or length of stay longer than 7 days.16
Risk factors for the development of ventilator-associated pneumonia (VAP) in pediatric patients include reintubation, genetic syndromes, immunodeficiency, and immunosuppression.17,18 In neonates, a prior episode of bloodstream infection is a risk factor for the development of VAP.19
Risk factors for the development of healthcare-associated urinary tract infection in pediatric patients include bladder catheterization, prior antibiotic therapy, and cerebral palsy.20
Physical
In addition to the presence of systemic signs and symptoms of infection (eg, fever, tachycardia, tachypnea, skin rash, general malaise), the source of healthcare-associated infections may be suggested by the instrumentation used in various procedures. For example, an endotracheal tube may be associated with sinusitis, tracheitis, and pneumonia; an intravascular catheter may be the source of phlebitis or line infection; and a Foley catheter may be associated with a urinary tract infection.
Patients with pneumonia may have fever, cough, purulent sputum and abnormal chest auscultatory findings such as decreased breath sounds, crackles or wheezes.
Patients with urinary tract infection may present with or without fever. Patients with cystitis can have suprapubic tenderness while those with pyelonephritis can have costovertebral tenderness. Upon inspection, their urine can be cloudy and foul-smelling.
Neonates on the other hand usually do not present with any of the above findings and may have very subtle and nonspecific signs of infection. Fever may or may not be present. Signs of infection can include temperature and/or blood pressure instability, apnea, bradycardia, lethargy, fussiness, and feeding intolerance.
Causes
In a survey done on 110,709 pediatric ICU patients, 6,290 healthcare-associated infections were noted.13 The top 3 major sites of infections, accounting for 64% of all healthcare-associated infections, were bloodstream infections (28%), pneumonia (21%), and urinary tract infection (15%). Each of these infections was strongly associated with use of an invasive device.
The top 3 pathogens in bloodstream infections were coagulase-negative staphylococci (38%), Enterococcus (11%), and S aureus (9%). Candida albicans accounted for about 5.5% of bloodstream infections. The top 3 pathogens for pneumonia were P aeruginosa (22%), S aureus (17%), and Haemophilus influenzae (10%). The top 3 pathogens for urinary tract infections were Escherichia coli (19%), C albicans (14%), and P aeruginosa (13%). Gram-negative enteric organisms accounted for about 50% of all urinary tract infections. The top 3 pathogens for surgical site infections were S aureus (20%), P aeruginosa (15%), and coagulase-negative staphylococci (14%).
Surgical site infections (SSI) occur within 30 days after the operative procedure or within 1 year if an implant was placed. Criteria for the diagnosis of SSI include purulent drainage at the site of incision, clinical symptoms of infection (such as pain, redness, swelling, etc), presence of an abscess, isolation of organism from the site culture, and clinical diagnosis of SSI by the surgeon.21
Rotavirus is the most common cause of acute gastroenteritis in hospitalized children, with greatest susceptibility in children younger than 3 years. Aside from having nonbloody diarrhea, patients may present with fever, vomiting, and abdominal cramps. Other viruses that can cause hospital-associated gastroenteritis include norovirus and adenoviruses. Gastroenteritis due to adenovirus can be especially debilitating in immunocompromised patients.
Clostridium difficile is the most important bacterial cause of healthcare-associated gastroenteritis. Associated clinical conditions include asymptomatic carriage, diarrhea, and pseudomembranous colitis. Diagnosis is suspected in a patient with diarrhea and recent history of antibiotic use (especially cephalosporins and clindamycin).
More on Hospital-Acquired Infections |
 Overview: Hospital-Acquired Infections |
| Differential Diagnoses & Workup: Hospital-Acquired Infections |
| Treatment & Medication: Hospital-Acquired Infections |
| Follow-up: Hospital-Acquired Infections |
| References |
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References
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Further Reading
Keywords
healthcare-associated infection, hospital-acquired infection, nosocomial infection, device-associated infection, ventilator-associated pneumonia, catheter-associated infection, line infection, phlebitis, bloodstream infection, urinary tract infection, surgical site infection, treatment, symptoms
