Hospital-Acquired Pneumonia: Challenges in Diagnosis and Management

Pneumonia remains a significant public health threat, most notably as the top infectious cause of death in children under age 5 worldwide.¹ In the United States, there were nearly 700,000 emergency department visits and 50,622 deaths due to pneumonia in 2014.²

Ironically, a large number of cases originate in the hospital: Pneumonia has been cited as the leading cause of hospital acquired-infection (HAI) in the United States, with more than 157,000 patients infected in acute-care hospitals in 2011.³ “Bacteria may enter the lower respiratory tract by micro- or bolus-aspiration of oropharyngeal organisms, inhalation of aerosols containing bacteria, or, less frequently, hematogenous spread from a distant body site,” according to experts at the Cleveland Clinic.⁴ An estimated 55% to 85% of  hospital acquired pneumonia (HAP) infections involve gram-negative bacteria, while 20% to 30% of cases involve gram-positive cocci.⁴

Pneumonia has also been found to be the top cause of death related to HAIs, as in 1 study showing that almost 36,000 patient deaths in US hospitals in 2002 were associated with HAP.⁵ The estimated rate of mortality from HAP is 33% to 50%.⁶ In addition to these outcomes, there is a steep financial cost for HAP — more than $40,000 per patient, with hospital stays lasting an average of 7 to 9 days longer.⁴

Risk Factors & Diagnosis

The main risk factors for HAP are intubation and mechanical ventilation (MV). In patients receiving MV, the incidence of HAP is 6 to 21 times higher compared with other patients, and some studies have found that almost 90% of these patients had been diagnosed with ventilator-associated pneumonia (VAP). HAP and VAP are sometimes referred to separately in the literature, or HAP may be assumed to include VAP.⁴

Additional risk factors include those that are modifiable — including aspiration, patient body position, enteral feeding, oropharyngeal colonization, stress bleeding prophylaxis, transfusion, and glucose control — and those that are nonmodifiable, such as patient age older than 70, immunosuppression, preexisting chronic lung disease, and previous thoracoabdominal surgery.⁶

Diagnosis is one of the primary difficulties in managing HAP. “Clinicians cannot use any one type of diagnostic modality to make a HAP diagnosis, and must rely on the combination of clinical examination, signs and symptoms, microbiologic testing, and radiographic findings,” explains Judith O’Donnell, MD, a professor of clinical medicine at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia, and director of the department of infectious disease prevention and control at Penn Presbyterian Medical Center. Chest computed tomography (CT) scans may overcall the presence of pneumonia, while changes in chest X-rays may be undetectable. Microbiology testing such as sputum or endotracheal aspirate cultures “may be falsely negative, or as often occurs in the chronically ventilated patient, can be falsely positive due to chronic respiratory tract colonization with bacteria,” she told Infectious Disease Advisor.

Prevention

The Centers for Disease Control and Prevention (CDC) published guidelines for the prevention of HAP in 2003, and the Infectious Disease Society of America and American Thoracic Society jointly published clinical guidelines for the management of patients with HAP and VAP.^7,8 Many hospitals have implemented programs to reduce the incidence of pneumonia. “The greatest focus has been on VAP, where a ‘bundle’ with a variety of components [that] can potentially lead to lower rates,” says Richard G. Wunderink, MD, a professor of medicine in the pulmonary and critical care division of the Northwestern University Feinberg School of Medicine in Chicago, Illinois, who has co-authored an extensive number of peer-reviewed papers regarding pneumonia.

“By far the most important prevention strategy for VAP is [the] use of daily awakening and daily spontaneous breathing trials to shorten the duration of mechanical ventilation,” he said in an interview with Infectious Disease Advisor. Examples of other components often included in these bundles are universal handwashing, decontamination of the oropharynx and skin with chlorhexidine, elevation of the head of the patient’s bed, and increased mobilization of ventilated patients. “While each of these components and others are likely to have a benefit, the real reduction comes from greater attention to all aspects.

Treatment and Antibiotic Resistance

As with many infectious diseases, antibiotic resistance poses a major challenge to the management of HAP. “Antibiotic resistance has, and will continue to, play a big role in HAP management, particularly in the ventilated patient population,” said Dr O’Donnell. She cites the increase in drug-resistant organisms such as Klebsiella spp and E coli, particularly in the critical care units of hospitals, and multidrug resistant (MDR) pathogens such as Pseudomonas aeruginosa.

In addition, many of the “antibiotics active against some of the MDR pathogens have poor penetration into the lung, further compromising our ability to treat these infections,” notes Dr Wunderink. He points to this as another example of how the lack of rapid diagnostics for MDR pathogens extends the length of time that patients receive suboptimal antibiotic therapy, and says that such a test would substantially reduce and refine empirical antibiotic regimens. There is still a need for “new antibiotics, particularly with different mechanisms of action, but we can forestall the widespread emergence of many MDR pathogens with less antibiotic exposure.”

Summary

Hospital-acquired pneumonia remains a significant threat to patients, especially because of the proliferation of MDR pathogens. Strict adherence to “bundles” of preventive measures set forth by hospitals is imperative.

References

1. Pneumonia. Centers for Disease Control and Prevention (CDC) website. Updated April 27, 2017. Accessed July 31, 2017.
2. National Center for Health Statistics. Pneumonia. Centers for Disease Control and Prevention (CDC) website. Updated January 20, 2017. Accessed July 31, 2017.
3. Healthcare-associated infections.  Centers for Disease Control and Prevention (CDC) website. Updated October 25, 2016. Accessed July 31, 2017.
4. Tedja R, Gordon S. Hospital–acquired, health care-associated, and ventilator-associated pneumonia. Cleveland Clinic. Published November 2013. Accessed July 31, 2017.
5. Klevens RM, Edwards JR, Richards CL Jr, et al. Estimating health care-associated infections and deaths in U.S. hospitals, 2002. Public Health Rep. 2007;122:160-166. doi:10.1177/003335490712200205
6. American Thoracic Society; Infectious Diseases Society of America. Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care Med. 2005; 171(4):388-416. doi:10.1164/rccm.200405-644ST
7. Healthcare Infection Control Practices Advisory Committee; Centers for Disease Control and Prevention (DCD). Guidelines for preventing health-care-associated pneumonia 2003 recommendations of the CDC and the Healthcare Infection Control Practices Advisory Committee. Respir Care. 2004; 49:926-939.
8. Kalil AC, Metersky ML, Klompas M, et al. Management of adults with hospital-acquired and ventilator-associated pneumonia: 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016;63:e61-e111. doi:10.1093/cid/ciw353

This article originally appeared on Infectious Disease Advisor