Identification of specific pathogens often isn't possible because of the difficulty of obtaining adequate specimens, although newer microbiological testing methods show promise. Thus treatment is often based on the likely pathogens and on the presenting level of severity. Most “textbook” lists of pathogens causing CAP begin with Streptococcus pneumoniae and include Chlamydophila, Haemophilus influenzae, Legionella species, Moraxella catarrhalis, Mycoplasma pneumoniae, Staphylococcus aureus, and group A streptococci.19 One recent study analyzed data for more than 2,200 patients for whom there was radiographic evidence of pneumonia and at least one specimen available for both bacterial and viral testing.31 It's worth noting that both human rhinovirus and influenza were detected more often than S. pneumoniae; the researchers suggested that improved “influenza-vaccine uptake and effectiveness” might decrease the incidence of CAP.31
Treatment. Prompt antibiotic therapy in any infectious process improves outcomes. Regimens for CAP vary, depending on the likely pathogen and the level of illness severity. Current guidelines for patients with CAP hospitalized in a non-ICU setting call for either a β-lactam and macrolide combination or a respiratory fluoroquinolone.30 In a randomized crossover trial, Postma and colleagues found β-lactam monotherapy to be “noninferior” to the two aforementioned strategies,32 but this is insufficient evidence to recommend a practice change. And in a study of patients sick enough to be admitted to an ICU, Pereira and colleagues confirmed that combination β-lactam with macrolide therapy resulted in lower in-hospital and six-month mortality rates.33
In patients hospitalized with CAP in an ICU setting, the most recent guidelines jointly issued by the Infectious Diseases Society of America (IDSA) and the American Thoracic Society (ATS) recommend more aggressive therapy.30 In general, treatment with a β-lactam antibiotic plus either azithromycin (Zithromax and others) or a respiratory fluoroquinolone is advised. In cases of community-acquired methicillin-resistant S. aureus (MRSA), vancomycin (Vancocin) or linezolid (Zyvox) should also be added. If Pseudomonas aeruginosa is suspected, treatment with an antipneumococcal, antipseudomonal β-lactam plus other drugs in various combinations is advised.
Patients with CAP should receive antibiotic therapy for at least five days, continuing until the patient has been afebrile for at least 48 hours and has no more than one CAP-associated sign of instability (such as continued need for oxygen therapy or an elevated white blood cell count).30 These discontinuation criteria were recently validated in a study by Uranga and colleagues.34
In cases of severe CAP and treatment failure, there is some evidence to support the use of adjunctive therapy with corticosteroids.35, 36 But this therapy remains controversial and further research is needed.19
HAP refers to pneumonia that develops during hospitalization. (An older term, health care–associated pneumonia, referred to pneumonia that developed in people who, though not hospitalized, had significant health care contact, such as by receiving dialysis or residing in nursing homes. This term has been removed from the most recent IDSA–ATS guidelines.) Additional risk factors for HAP include being hospitalized for more than 48 hours and being a surgical patient.37 Although VAP also usually develops during hospitalization, it is discussed separately in the literature and in this article.
Treatment. The most significant difference between CAP and HAP is the greater risk hospitalized patients have for the development of MDRO pneumonia.38, 39 Thus, treatment recommendations vary somewhat from those for CAP, and are based on a patient's risk of mortality and MDROs; they are similar to those for VAP, described below. The IDSA–ATS guidelines for HAP strongly recommend antibiotic therapy for seven days in duration, despite a “very low quality” of evidence.39 Shorter courses of therapy for HAP have been studied, but there is insufficient evidence with regard to nonventilated patients in particular to support a change in practice.40
VAP. The CDC defines VAP as a pneumonia that develops when the patient has been on mechanical ventilation for more than two days.23 Additional risk factors for VAP include having suffered major trauma or brain injury.37 Overall, VAP rates have been decreasing.41 This may be owing to a heightened focus on preventive practices such as daily “sedation vacations,” endotracheal tubes with subglottic secretion drainage ports, elevating the head of the bed, early mobility, oral care with chlorhexidine, and more aggressive extubation.42 Nonetheless, clinical surveys indicate that as many as 5% to 15% of patients on ventilators develop pneumonia.42, 43
For diagnostic purposes, noninvasive sampling with semiquantitative cultures is recommended (such as endotracheal suction tube specimens), rather than more invasive methods (such as mini-bronchoalveolar lavage or bronchoscopic specimens).39 The use of clinical scoring systems such as the Clinical Pulmonary Infection Score is not recommended.
Treatment. Many institutions use procalcitonin and C-reactive protein levels to discern the need for antibiotic therapy in cases of suspected infection. But because of insufficient evidence, the current IDSA–ATS guidelines for treating HAP and VAP do not recommend their routine use when considering whether to begin antibiotic therapy.39 This may change (at least for the sickest patients), as a recent meta-analysis of procalcitonin use in guiding antibiotic treatment decisions showed a lower 30-day mortality rate (21.1% versus 23.7%) and a one-day decrease in antibiotic use in the group whose treatment was guided by procalcitonin levels compared with controls.44 Because high procalcitonin levels may also be found in inflammatory processes such as severe trauma, surgery, cardiogenic shock, and autoimmune disease caution must be used in their interpretation.
Treatment for VAP should begin with aggressive empiric antibiotic therapy as soon as VAP is suspected. It should be based on local antibiogram data regarding the prevalence of MDROs in the clinical area and on guideline recommendations. Precise regimens for VAP vary, depending on the likely pathogen and the level of illness severity. At minimum, treatment should include broad-spectrum antibiotics that target S. aureus, P. aeruginosa, and other gram-negative bacteria.39 In areas with greater than 10% prevalence of multidrug-resistant P. aeruginosa, an anti-MRSA agent is also recommended, at least until definitive culture results are obtained. Once such results are in, this broad-spectrum regimen should be scaled back to a more targeted regimen, in order to lower the risk of development of MDROs in both the patient and the clinical environment. The IDSA–ATS guidelines for VAP strongly recommend antibiotic therapy of seven days in duration, based on moderate-quality evidence.39
Prevention and treatment. In summary, evidence-based recommendations for managing hospitalized patients at risk for or who have CAP, HAP, or VAP include the following.19, 30, 39, 42, 45
- Begin empiric antibiotic therapy quickly, ideally within three hours of initial symptoms.
- In patients with CAP, use a validated severity scoring method to gauge level of illness and risk of worsening.
- Use short durations of antibiotic therapy if symptoms resolve (CAP, five days; VAP or HAP, seven days).
- Choose antibiotics for HAP or VAP based on local data per hospital antibiogram.
- Keep the head of the patient's bed elevated at 30° or more to prevent aspiration.
- Use endotracheal tubes with subglottic suction.
- Encourage early ambulation.
- Aggressively manage electrolytes and fluid balance and hypoxemia.
- General infection prevention strategies, such as proper handwashing and encouraging at-risk populations to get the influenza vaccine, are also important.
SURGICAL SITE INFECTIONS
Surgical site infections (SSIs) account for nearly 20% of all HAIs and are associated with significantly longer hospital stays and an increased risk of death.46 Overall, approximately 2% to 5% of patients undergoing surgery are affected.46 But the rate for patients undergoing specific surgeries and facing associated risk factors can vary widely. For example, in a recent study by Sanger and colleagues of 851 patients undergoing abdominal surgeries, 19.6% developed SSIs while recovering in the hospital.47 It's estimated that up to 60% of SSIs are preventable.48
Risk factors may be patient or procedure related, with patient-related factors classified as modifiable or nonmodifiable.46, 48 Modifiable risk factors include alcohol use, smoking, glycemic control (in people with diabetes), obesity, preoperative hypoalbuminemia, and use of immunosuppressive medications. Nonmodifiable factors include age, history of radiotherapy, and recent skin or soft tissue infection. Clinical evidence of SSI may include fever; an elevated white blood cell count; edema, erythema, or excessive pain at the surgical site; wound dehiscence; foul odor; and purulent drainage at the surgical site. It can be initially difficult to distinguish normal postoperative surgical wound appearance from an infected surgical site. Frequent, serial examinations of the site, preferably by the same person, can be helpful. There is evidence supporting daily clinical wound assessment as a significant early predictor of SSI.47
Prevention and treatment. Strategies to prevent SSIs are well documented and supported by several evidence-based professional guidelines.46, 48, 49 These strategies include smoking cessation, glucose control, not shaving the surgical site (clipping only if necessary), and maintaining perioperative normothermia. Antibiotic prophylaxis is recommended only when indicated; when so indicated, it should be administered within one hour of incision with an appropriate agent (within two hours for vancomycin or fluoroquinolones), and should be discontinued within 24 hours of surgery.46, 48, 50
Further recommendations include preoperative bathing with chlorhexidine, perioperative administration of supplemental oxygen for patients undergoing general anesthesia, and consideration of the use of antibiotic sutures for wound closure.46, 49 Although preoperative chlorhexidine bathing is recommended, optimal timing and number of applications remain unclear. Postoperatively, early showering (12 hours after surgery) has not been shown to increase SSI rates.46 The use of wound vacuum therapy is increasingly common in treating SSIs and is recommended for certain wounds.46, 49 But both topical wound antibiotic treatment and the use of silver-containing dressings have shown mixed results in the literature, and neither is routinely recommended by current guidelines.46, 49
Once an SSI is diagnosed, treatment recommendations include opening the wound to allow drainage.51 This involves removing staples or sutures and possible incision and drainage at the site if indicated. Depending on the site and severity of infection, IV or oral antimicrobial treatment may be ordered for some patients, particularly if the patient is immunocompromised or physically weak owing to age or comorbidities.51
In all surgical patients, postoperative monitoring for necrotizing fasciitis is crucial. Patients most at risk are those who have diabetes, are immunocompromised, or have suffered traumatic wounds.52 Clinical findings suggestive of necrotizing fasciitis include excessive pain or tenderness (disproportionate to what is usual for a given surgery), fever, soft-tissue edema, and skin bullae or necrosis. Imaging may show gas in the tissues (suggestive of group A streptococcal infection), although the absence of gas doesn't rule out necrotizing fasciitis. If necrotizing fasciitis is suspected, immediate consultation with a surgeon experienced with this infection is warranted, as open surgical inspection and biopsy are the most definitive means of diagnosing and treating the infection.
GI INFECTION: C. DIFFICILE
Incidence rates of C. difficile infection (CDI) have steadily and dramatically risen during the past 20 years in both community and inpatient populations. One surveillance study showed a near doubling of such rates in hospitalized adults between 2001 and 2010, from 4.5 to 8.2 cases per 1,000 patient discharges.53 Although estimates vary, CDIs reportedly account for 15.5% to 21.3% of HAIs3, 4 and cause from 14,000 to 29,000 deaths annually.54, 55 Multiple recurrences of CDI are common in both inpatient and community settings.54, 56
The top three risk factors for CDI are antibiotic use, exposure to the organism, and serious comorbidities; other factors include GI surgery or manipulation (such as colonoscopy), immunocompromise, longer lengths of stay, older age, and proton pump inhibitor use.54, 57, 58 Risk factors for recurrence include chronic kidney disease; female sex; nursing home residency; and the use of antibiotics, proton pump inhibitors, or corticosteroids within 90 days of CDI diagnosis.54
Diagnosis of CDI should involve use of a multistep testing algorithm. The current guidelines, jointly issued by the IDSA and the Society for Healthcare Epidemiology of America (SHEA), recommend testing patients who have three or more unformed stools in 24 hours with no laxative use.59 Screening proceeds by following a testing algorithm, often first testing for glutamate dehydrogenase, which is an enzyme produced by all strains of C. difficile. This test has a high negative predictive value60; thus, if the result is negative, no further testing is needed. If the result is positive, this should be confirmed with either a toxin test or a nucleic acid amplification test, such as the polymerase chain reaction test.59 For an evidence-based testing algorithm, see Figure 1.59
Prevention and treatment. As soon as CDI is suspected, it is appropriate to institute contact precautions and conduct room disinfection with a sporicidal cleaning product, according to the IDSA–SHEA guidelines.59 For routine use, either soap and water or alcohol-based hand rubs or sanitizers are acceptable for hand hygiene. During outbreaks or in hyperendemic settings, staff should use soap and running water with vigorous rubbing to remove any spores present, although the quality of supporting evidence is low. Once a patient is discharged or if contact precautions are discontinued, terminal cleaning of the room and equipment are recommended. Adjunctive disinfection methods such as with ultraviolet light may be helpful. Contact precautions may be discontinued once the patient has at least 48 hours without diarrhea, but institutions with higher rates of CDI should continue using contact precautions until the patient is discharged.
Treatment of CDI previously consisted of oral or IV metronidazole (Flagyl); newer data support the use of oral vancomycin or fidaxomicin (Dificid) instead.59 Severe infection should be treated with oral vancomycin. If ileus is present or if absorption is questionable owing to poor gut function, the recommended treatment is vancomycin per rectum along with IV metronidazole.
A recent large study of patients with CDI who were treated with either vancomycin or metronidazole found no difference in risk of recurrence between the groups; but in cases of severe CDI, the risk of 30-day mortality was significantly lower among those who received vancomycin.56 The IDSA–SHEA guidelines recommend treating recurrences aggressively with one of three options: a prolonged “taper and pulse” course of vancomycin; a 10-day course of fidaxomicin; or, if metronidazole was used initially, a 10-day course of vancomycin.59
Given the profound effects that HAIs can have on patient outcomes and health care costs, it's clear that infection prevention and control measures are paramount. Good antibiotic stewardship has been associated with decreased incidences of and colonization by many MDROs, including gram-negative bacteria and MRSA, as well as a lower incidence of CDI,61 and should be routine practice in every setting. Nurses in clinical practice can contribute to HAI prevention and control in the following ways.
- Promote good antibiotic stewardship. Encourage daily medical team review of the need for any antibiotics the patient is receiving and discuss the potential for deescalation to the most narrow-spectrum agent that would be effective.
- Practice and preach good hygiene and contact precautions. Wash hands before and after each patient or environmental contact. Maintain strict contact precautions for those patients who are infected or colonized with MDROs or C. difficile. Keep long hair contained. Adhere to the evidence-based practice recommendations described above, and continue learning about infection prevention.
- Promote a clean patient environment. Encourage leadership to consider the use of adjunctive environmental cleaning methods such as ultraviolet light.
- Recognize and report early symptoms of infection to the medical team.
- Support the patient's nutritional status with enteral nutrition as soon as feasible.
Improving patient outcomes and decreasing infection rates require a multidisciplinary approach with strong leadership support, impeccable nursing assessment and care, and adherence to evidence-based guidelines for medical treatment.
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For 56 additional continuing nursing education activities on the topic of preventing hospital-acquired infections, go to www.nursingcenter.com/ce.
Keywords:Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.
Clostridioides difficile; community-acquired pneumonia; health care–associated infection; hospital-acquired pneumonia; multidrug-resistant organisms; surgical site infection; ventilator-associated pneumonia