Hospital acquired infections (HAIs) are a frequent complication of intensive care accounting for prolonged intensive care unit (ICU) length of stay, morbidity, suffering, and death. According to the Centers for Disease Control and Prevention (CDC), about one in every 20 patients will develop an HAI. Such infections were long recognized by clinicians as an inevitable hazard of hospitalization and are most often associated with invasive medical devices or surgical procedures.3
Central line associated bloodstream infections (CLABSI) are common in the United States accounting for nearly 100,000 bloodstream infections annually with half occurring in the ICU setting. While one third of these infections are attributable to gram negative organisms, other organisms like coagulase-negative staphylococci, Staphylococcus aureus, and enterococcus predominate. Host factors associated with increased risk for CLABSI include neutropenia, immunosuppression, total parenteral nutrition (TPN) use, chronic illness, and burn. Prolonged catheter use, conditions of insertion, and catheter site care also play a role in the development of CLABSI. For patients with suspected or confirmed CLABSI, the indwelling catheter should be removed and cultured with the institution of empiric antibiotic therapy. The initial selection of antibiotic depends on the severity of the infection, but generally vancomycin is used because of its activity against coagulase negative staphylococci and Staphylococcus aureus. Ceftazidime or cefepime may be needed for severely ill or immunocompromised critically ill patients.
Urinary tract infections account for more than 15% of infections reported by hospitals. Virtually all health care associated UTIs are caused by instrumentation of the urinary tract. A catheter-associated UTI (CAUTI) is a UTI where an indwelling urinary catheter was in place for more than two days. The majority of cases are caused by Escherichia coli followed by Pseudomonas aeruginosa, klebsiella species, and enterobacter species. Cefepime, ceftazidime, piperacillin-tazobactam, aztreonam, ciprofloxacin, and meropenem are generally first-line agents. In addition to sterile unobstructed closed drainage systems, prompt removal of urinary catheters is the single best strategy for CAUTI prevention.
Ventilator associated pneumonia (VAP) is a hospital acquired pneumonia that occurs 48 hours or more after the institution of mechanical ventilation. It is the most common nosocomial infection afflicting patients with respiratory failure and accounts for nearly half of all antibiotics used in the ICU setting. Nearly 20% of mechanically ventilated patients will get a VAP during their ICU course. VAP is caused when the normal host defense mechanisms are bypassed with the endotracheal tube and microaspiration of contaminated oropharyngeal secretions occurs. Rapid colonization of the oropharynx with gram negative bacteria occurs following antibiotic use and illness secondary to resultant compromise of host defenses such as ciliated epithelium, mucus, and glottis. Patients are unable to cough and the contaminated secretions pool above the endotracheal tube cuff and migrate along the airway. Biofilm, impervious to systemic antibiotics, forms along the endotracheal tube and serves as a breeding ground for bacterial growth which ultimately leads to infection.
The CDC National Healthcare Safety Network (NHSN) implemented a ventilator-associated events (VAE) surveillance program in 2013.4 This surveillance algorithm uses objective elements to identify complications associated with mechanical ventilation. VAP is included in the algorithm, which starts with the presence of a ventilator-associated condition (VAC), a period of respiratory deterioration following a sustained period of stability or improvement on the ventilator (eg, changes in PEEP or FiO2). The second tier definition, infection-related ventilator-associated complication (IVAC), requires that patients with VAC also have an abnormal temperature (temperature > 38°C or < 36°C) or white blood cell count (WBC ≥ 12,000 cells/mm3 or ≤ 4,000 cells/mm3), and requires the initiation of a new antibiotic for treatment of presumed infection. The third-tier definition is probable VAP and requires that patients with IVAC also have purulent respiratory secretions or laboratory evidence of respiratory infection. For quantitative cultures, a bacterial density of at least 106 CFU/ml for endotracheal aspirate, 104 CFU/ml for bronchoalveolar lavage, and 103 CFU/ml for protected specimen brush and for semiquantitative cultures, at least moderate growth of bacteria.
Risk factors for VAP include a supine position, previous broad spectrum antibiotic exposure, reintubation, acute respiratory distress syndrome (ARDS), prolonged mechanical ventilation, and trauma. The most common pathogens to consider for VAP are Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumonia, acinetobacter species, Streptococcus pneumonia, and Haemophilus influenza. Polymicrobial pneumonia is common and one should note that multi drug resistance is increasingly frequent in the ICU setting, particularly for patients with prolonged intubation, prior hospitalizations or ICU admissions, immunosuppression or those requiring hemodialysis. All ventilated patients without contraindications should be maintained in the semi recumbent position with the head of the bed raised 45° and be weaned from mechanical ventilation as soon as possible.
Hospital hand hygiene protocols have been shown to reduce the risk of certain HAI. The World Health Organization estimates that nearly 2 million patients each year are affected by poor hand hygiene practices in hospitals. A shocking number of health care providers fail to embrace hand hygiene. Healthcare workers should wash their hands for 15 to 30 seconds with soap and water or an approved alcohol based hand rub before and after patient contact.