Nursing Home–Acquired Pneumonia

Etiology

Pneumonia occurs when a sufficient volume of a pathogenic organism bypasses the body’s cough and laryngeal reflexes and makes its way into the pulmonary parenchyma. This can occur from being exposed to large volumes of pathogens in inspired air, increasingly virulent pathogen exposure, aspiration, or impaired host defenses.[1] Given the different environments in which one may acquire pneumonia, the diagnosis is often broadly classified into community-acquired, or hospital-acquired.  The before mentioned binomial classification is important; as it guides clinical treatment based on suspected organisms. Nursing home-acquired pneumonia is classified as part of the hospital-acquired group, as patients are at increased risk for infection with opportunistic and multi-drug resistant organisms.[2] This is secondary to close living conditions, close quarters with commonly ill residents, chronic antibiotic use, and immune-suppressive therapies such as chemotherapy.

Although the nursing home population has an increased likelihood of having more virulent pathogens, the most common pathogens isolated remain in-line with the general population, including Streptococcus pneumoniae, Haemophilus influenzae, and Klebsiella pneumoniae. The more virulent organisms suspected in nursing home-acquired pneumonia are associated with common risk factors. K. pneumoniae and Pseudomonas aeruginosa frequently colonize patients during repeat hospitalizations, and patients are at increased risk if they have invasive lines placed during hospitalization, or if they require endotracheal intubation and mechanical ventilation. Methicillin-resistant Staphylococcus aureus (MRSA) is another presumed flora of patients who are residents of extended care facilities and is now becoming more common in the community; MRSA is ubiquitous among chronically ill and frequently hospitalized patients. Another common group of organisms is anaerobic microbes that commonly inhabit the oral-pharynx, such as Peptostreptococcus, Bacteroides, and Provotella species.[3] Residents of nursing home facilities frequently have comorbidities such as cerebrovascular disease, confusion and musculoskeletal deconditioning, making aspiration more likely, therefore, increasing their probability of having anaerobic bacterial species in collected sputum samples. Immunosuppressed patients, such as those undergoing chemotherapy, are at increased risk for fungal organisms such as Candida species and opportunistic pathogens such as Pneumocystis jiroveci.  Although not inclusive the above are commonly encountered pathogens when treating the nursing home patient with pneumonia.

Epidemiology

Nursing home-acquired pneumonia occurs in an estimated 1-2 patients for every 1000 days of nursing home residence.  Nursing home residents diagnosed with pneumonia and requiring hospitalization can have mortality ranging from 13 to 41%. An individual’s risk is multifactorial including their functional status, the presence of underlying pulmonary disease, age, and comorbidities such as stroke, musculoskeletal disorders, and immunosuppression.

Nursing home-acquired pneumonia fits under the umbrella term of healthcare-associated pneumonia. Healthcare-associated pneumonia represents patients at increased risk of having multi-drug-resistant organisms and increased incidence of gram-negative infections.[4]  High-risk individuals include those patients who:

• Live in nursing, or long-term care facilities
• Receive intravenous (IV) therapies such as chemotherapy or have received wound care within the past 30 days
• Hospitalized for more than 2 days in the prior 90 days
• Receive hemodialysis

Pathophysiology

When the inoculating organisms overwhelm the host defense, there is the proliferation of the infectious agent. The pathogen's replication initiates the host immune response. Then further inflammation, alveolar irritation, and impairment occur. This leads to the classic signs and symptoms of a cough, sputum production, dyspnea, tachypnea, and hypoxia. However, elderly patients, who represent a disproportionate majority of nursing home residents, often present with more nonspecific complaints such as confusion, lethargy, falls, and fever. 

The elderly and chronically ill are more likely to aspirate, allowing polymicrobial oral flora to escape an already impaired gag reflex and seed the lower respiratory tract.[3] This can be sterile or have a sub infectious threshold of bacterial organisms resulting in chemical pneumonitis. If an adequate inoculum reaches the parenchyma and multiplies, it will cause aspiration pneumonia, which should be suspected if there are bilateral consolidations. Chronically ill patients and those frequently exposed to the healthcare environment are more likely to be colonized with increasingly resistant and virulent organisms due to repetitive antibiotic exposure, wounds, invasive lines (percutaneous gastrostomy tubes, Foley catheters, and ports), and prior mechanical ventilation.

History and Physical

Elderly patients, who are the primary focus for nursing home-acquired pneumonia, often present with more nonspecific complaints such as confusion, lethargy, and falls.[5] It is important to observe for the more typical symptoms and signs such as a cough, shortness of breath, sputum production, fever, tachypnea, and hypoxia.[6] Ideally, history will be obtained from the patient, but if altered mentation or baseline dementia are present, taking a history from caregivers and family members is crucial to establish a timeline, risk factors, history of drug-resistant infections, or if any deterioration from baseline is present. Given the frequent decreased utility of history in this patient population, a thorough physical exam is essential. It is important to evaluate hydration status, respiratory mechanics, and for a change in mental status, as these can all indicate the severity of illness. On auscultation, be vigilant for the presence of rales unilaterally, which is expected with lobar pneumonia, and bilaterally, which may indicate aspiration pneumonia or acute respiratory distress syndrome.

Evaluation

The evaluation of the long-term care facility resident for pneumonia is often much more resource intensive than the same evaluation in a young and healthy patient. Pneumonia is a clinical diagnosis, with supplementation of a chest x-ray or chest CT scan serving as the confirmatory gold standard. Well-appearing residents, without concerning vital signs and benign physical exam can frequently be treated based on clinical presentation, or with the addition of chest imaging for confirmation. Typically, two or more abnormal vital signs is criteria for admission.  Due to delayed presentation and the nonspecific nature of their presentations; frequently a full medical workup including labs and imaging must be performed.  It is crucial to screen these patients for evidence of systemic inflammatory response syndrome which includes: fever/hypothermia, tachycardia, tachypnea, and leukocytosis/leukopenia. 

Patients meeting two out of four criteria, along with a presumed source of pneumonia, meet sepsis criteria and have an increased risk of morbidity and mortality.[7] Additional labs obtained in these patients include: renal function, liver function and lactic acid, to determine if there is evidence of end organ hypoperfusion.  These patients require blood cultures to screen for bacteremia and based on clinical discretion; urinary antigen testing, respiratory panels and sputum samples to help guide antimicrobial stewardship.

Disposition will factor in the patients clinical exam, vital signs and lab studies if obtained.  Frequently encountered decision-making tools include:

CURB 65 Score[8]

• (C) Confusion
• (U) Uremia greater than 19
• (R) Respiratory rate greater than 30
• (B) Systolic blood pressure less than 90
• (65) Age older than 65 years

Using this score, patients receive points for any of the above criteria they meet and their mortality is risk stratified. Typically, patients with 0 or 1 point can be managed outpatient; whereas, patients with 2 or more points have morality greater than 9.2% and require hospital admission.

Pneumonia Severity Index[5]

This score is multifactorial and accounts for comorbidities, vital signs, imaging, and labs. Points are awarded for age and gender, along with comorbidities such as malignancy, cerebrovascular, liver and renal disease. It also gives points for confusion and nursing home resident status. It uses vitals signs such as temperature, blood pressure, heart rate, and respiratory rate. Finally, you also consider chest x-ray findings and labs values from a complete blood count, basic metabolic profile and blood pH.

Treatment / Management

The management of nursing home-acquired pneumonia frequently occurs in the hospital, but in a select patient population, it can be managed successfully in the nursing home. Well-appearing individuals, with normal hydration status and reassuring vital signs, can frequently be discharged with an oral fluoroquinolone, or amoxicillin/clavulanic acid, plus azithromycin with close follow-up. For patients who have lab abnormalities, mildly deranged vital signs, or have comorbidities requiring hospitalization; first-line treatment is frequently an intravenous fluoroquinolone versus ceftriaxone plus azithromycin.[9] The final group of patients are those who appear acutely ill, have abnormal vital signs (such as hypotension or respiratory distress) and those patients who screen positive for sepsis. For these patients, empiric treatment with broad-spectrum antibiotics is recommended with potential narrowing as culture data allows, or as the patient clinically improves.

Empirical broad-spectrum antibiotics frequently include cefepime or piperacillin-tazobactam; for antipseudomonal and broad gram-negative coverage, with the addition of vancomycin for broad gram-positive coverage including MRSA.[2]  In individuals who you suspect aspiration as the underlying etiology, anaerobic coverage with piperacillin-tazobactam or metronidazole is an appropriate addition to therapy.[3](A1)

Adjunct therapies include antipyretics, volume resuscitation, vasopressor support, and non-invasive positive pressure ventilation/mechanical ventilation as indicated. 

Differential Diagnosis

As mentioned above, nursing home patients who present with pneumonia may present with the classic symptoms of a cough, sputum production, and dyspnea. However, with frequently delayed presentations and nonspecific symptoms such as falls, confusion, and lethargy, it is important to consider all sources of infection at initial presentation. This includes common etiologies such as urinary tract infections and cellulitis and those infections less common, such as meningitis and intra-abdominal pathologies. This population also has a high incidence of cardiac disease in patients presenting with dyspnea and hypoxia. Therefore, it is prudent to consider acute coronary syndrome. Patients in this population are frequently immobilized or minimally mobile. They also may have a history of malignancy and underlying respiratory disease. Therefore, in patients with primary respiratory symptoms, it is important to consider airway diseases such as chronic obstructive pulmonary disease and thromboembolic disease.

Prognosis

The mortality of nursing home-acquired pneumonia ranges from 13 to 41%. Ultimately, a patient’s morbidity and mortality will be affected by many factors including age, comorbidities, time before presentation, virulence of organism, presence of bacteremia, and if the patient requires intensive car unit (ICU) admission. Presenting in septic shock or respiratory failure carries a significantly worse prognosis. Pneumonia carries increased mortality[6] in this patient population, and they achieve optimal outcomes with early and aggressive intervention.