Author: Scott A. Flanders University of Michigan 2008-08-18
Introduction
Pneumonia generally refers to an
infection of the lung tissue, or lung parenchyma (the functional parts
of the lung), and is considered a type of upper respiratory infection.
The term “pneumonia” is also used to describe non-infectious
inflammatory conditions of the lung that often have no known origin, but
this knol will focus solely on community acquired pneumonia, which has
identifiable, infectious origins. Please note as well, that this knol
will NOT cover conditions such as rhinitis, sinusitis, pharyngitis,
tracheitis, and bronchitis, which are all upper respiratory infections
that develop higher in the respiratory tree and are generally considered
less severe than pneumonia.
- Community Acquired Pneumonia (CAP): Pneumonia that develops in people who are generally living independently in the community.
- Health
Care Associated Pneumonia: This class of infection affects people who
have had contact with the health-care system including:
- Recent hospitalization (for 48 hours or more within the last 90 days)
- Residence in a nursing home, or long-term care facility
- Home infusions (intravenous (IV) antibiotics or other IV therapy) or wound care
- Dialysis
Hospital Acquired or Nosocomial Pneumonia
This
is usually considered a complication of a hospitalization that was
required for an unrelated process and is defined as pneumonia that
develops more than 48 hours after admission to the hospital.
Ventilator Associated Pneumonia
A lung infection developing in a patient who is on a ventilator or breathing machine in the hospital.Community acquired pneumonia is a common and serious illness causing substantial morbidity and mortality. There are an estimated five to ten million cases annually in the U.S. that result in nearly one million hospitalizations. The mortality rate in less ill patients (patients who do not require hospitalization) is generally less than 5%, but in patients who require hospitalization mortality is between 10 and 15%. In the sickest patients -- those who require admission to an intensive care unit (ICU) – mortality can exceed 35-40%.1
Microaspiration
The most common way people develop pneumonia is by sucking in (aspirating) spit full of bacteria, which trickles down into the lungs. This is a common phenomenon that occurs in most people when they sleep. Usually it is not a problem, because the airways of healthy adults who do not smoke contain small hairs that move secretions back up and out; the secretions that do get to the lungs are usually handled effectively by the immune system. But people with a lot of secretions (such as during a cold) – or secretions that carry large amounts of colonizing bacteria – are more likely to get pneumonia.Macroaspiration
Pneumonia can also develop after aspiration of large quantities of secretions or vomit if bacteria grow in the aspirated material. This is a particular type of community-acquired pneumonia called aspiration pneumonia. It occurs more commonly in individuals who cannot control their secretions (such as in states of confusion, seizures, alcohol abuse, etc.). Even if bacteria do not grow in the aspirated material, the aspiration of stomach contents (food and acids) into the lung can often lead to an inflammatory response that looks like pneumonia, but does not need antibiotic treatment (see below under “What else could it be?”).Inhalation
Despite popular opinion, inhaling an infectious organism and “catching” pneumonia is less common than other causes. Viral infections are more likely to be transmitted in this manner and can lead to pneumonia, but only the most aggressive or virulent bacteria, such as tuberculosis (Mycobacterium tuberculosis), legionella (Legionella pneumophila), or anthrax (Bacillus anthracis) are transmitted this way. Fortunately, these organisms are uncommon.Blood Stream Source
Rarely, bacteria can enter the blood stream and then “seed” the lung. This is more common with certain types of bacteria such as Staphylococcus, which enters the blood because of IV catheters, IV drug use, or a skin infection.
While some risk factors for acquiring pneumonia
are obvious and related to individual behavior (i.e., aspirating vomit,
exposure to tuberculosis, or smoking) many more are related to
underlying medical conditions or other variables that have little or
nothing to do with individual behavior. Age alone is a strong risk
factor and according to one estimate over 900,000 cases of pneumonia in
the U.S. occur annually in people 65 years of age and older.
Alzheimer’s, smoking related lung diseases, residence in a nursing home,
immune system dysfunction (AIDS, diabetes, immune-depressing medication
use such as steroids), structural lung diseases, and alcoholism all
place individuals at increased risk of developing pneumonia. In
addition, recent research has suggested that potent gastric acid
suppressing medications (proton-pump inhibitors or PPIs) used to treat
acid reflux increase the risk of developing pneumonia.2
Bacterial Pneumonia
Bacteria are the most common disease-causing agents (pathogens) in cases of pneumonia and are the only ones that will be affected by antibiotics (antibiotics do not kill viruses). Although pneumonia can be caused by myriad organisms, there are only a handful that cause most infections (Table 1). The type of bacteria causing an infection depends on both the setting in which pneumonia develops as well as individual risk factors and community/environmental conditions associated with particular bacteria (Table 2). The most common infecting bacteria in most settings are Streptococcus pneumoniae (pneumococcus) and thus all antibiotics used for pneumonia must have activity against this organism.3
Until
the late 1980’s, almost all pneumococcus was easily killed by the
penicillins and many other antibiotics. That all changed when resistance
began to develop. The emergence of drug-resistant S. Pneumoniae
(DRSP) is well documented in the U.S. DRSP began to appear in the 1980’s
and by 2003 up to 30% of pneumococcal isolates had some level of
resistance to penicillins and penicillin-like drugs (beta-lactam
antibiotics). Risk factors for infection with DRSP include extremes of
age (less than two and over 65), exposure to children in day care,
recent beta-lactam use, alcoholism, immunosuppression, and medical
comorbidities. In addition, between 25-30% of all pneumococcal isolates
are also resistant to the macrolide antibiotics (azithromycin,
clarithromycin, and erythromycin). The clinical importance of drug
resistance among pneumococcal isolates has been debated, but it appears
that current levels of resistance have not necessarily caused treatment
to fail, even in patients treated with beta-lactam antibiotics. This is
likely due to the fact that most beta-lactam antibiotics achieve high
concentrations in both the blood and lung that overwhelm DRSP. Whether
resistance to macrolides is clinically meaningful is even more
controversial, but recent research does suggest that patients with
macrolide resistant pneumococcus are at risk for treatment failure with
macrolides. A variety of antibiotics with enhanced activity against DRSP
have been developed to combat the problem of antibiotic resistance. The
newer fluoroquinolones (e.g., levofloxacin, moxifloxacin) are one
example, but there are even reports of resistance to these agents
developing in patients who have been previously exposed to these drugs.
In the outpatient setting (non-hospitalized), Mycoplasma pneumoniae and Chlamydia pneumoniae are
common pathogens and most recommended antibiotics for the treatment of
community-acquired pneumonia target these bacteria, which are generally
referred to as “atypical organisms” because they are harder to isolate
with traditional microbiologic techniques and tend to cause more mild
symptoms in generally healthy people. The term “walking pneumonia” has
also been used to describe these infections, although many people
receive that label without really knowing whether they were infected
with Mycoplasma or Chlamydia. The importance of treating these two
organisms, however, has been questioned by recent research that suggests
patients do just as well whether they receive an antibiotic that kills
mycoplasma and chlamydia or not.4 Legionella species
are a type of bacteria (also termed “atypical”) that cause pneumonia in
patients with impaired immune systems and structural lung disease like
chronic obstructive pulmonary disease (COPD); legionella species also
have been associated with outbreaks in the setting of contaminated
aerosolized water (i.e., air conditioners and produce water sprayers at
grocery stores.). Legionella species, unlike the other atypicals, can
cause serious infections and so all critically ill patients with
pneumonia receive antibiotics active against these bacteria.
An important type of bacteria that is emerging as a new threat to otherwise healthy people is Staphylococcus aureus
or staph infections. Staph pneumonia has long been known to be a
complicating bacterial infection that develops after a bout of the flu
(influenza). Similarly, people who have been previously hospitalized are
known to be at risk for antibiotic resistant staph infections, referred
to as methicillin resistant staph aureus (MRSA). Recently, strains of
MRSA, distinct from those usually found in hospitals, have become a
potential cause of infections in the community. These infections, termed
community associated MRSA (CA-MRSA), have occurred in clusters
(outbreaks in athletes, military recruits, prisoners) and can be spread
by skin to skin contact, contaminated towels and surfaces, open sores,
and crowded living conditions. While most CA-MRSA infections cause boils
or pimples on the skin, it can also cause pneumonia (most commonly
after an influenza infection). CA-MRSA pneumonia is quite severe, often
requiring ICU level care and is associated with high rates of mortality.
Previous skin infections or boils are risk factors for CA-MRSA
pneumonia. The Centers for Disease Control (CDC) has more information on
these infections on its website. (http://www.cdc.gov/ncidod/dhqp/ar_mrsa_ca.html)
Viral Pneumonia
Influenza is the predominant viral cause of CAP, but other viruses such as parainfluenza virus, respiratory syncytial virus (RSV), and adenovirus can also cause pneumonia. Viruses are the cause of pneumonia in nearly 35% of outpatient settings and up to 20% of hospitalized cases and are particularly problematic in the elderly, patients with lung and heart disease, and immunocompromised patients where mortality may be quite high. Viral pneumonias are more common in winter months, but are hard to distinguish clinically from bacterial pneumonia. Unless specific diagnostic tests for viruses are done (which are primarily useful only in influenza) the virus causing a case of pneumonia is often not known. In addition, patients with a viral pneumonia can develop a “secondary” bacterial pneumonia as a complication, and thus it is not uncommon to initially treat severe pneumonia with antibiotics even if a virus is suspected.Less common causes
A variety of other agents can cause pneumonia, but are not commonly encountered. Fungal pneumonias can be seen, but are more common in immunocompromised patients (patients receiving immunosuppressive drugs or who have AIDS) and are most often due to coccidiomycosis (inhaled dust in the desert southwest), histoplasmosis (exposure to soil in the Mississippi River basin), or Cryptococcus (exposure to bird / bat droppings). In AIDS patients Pneumocystis jiroveci (formerly PCP) is of particular concern. Recently, agents of bioterrorism such as anthrax, plague, and tularemia have become a theoretical concern, because they often present as pneumonia, and should be suspected in outbreak settings among otherwise healthy patients. Emerging pathogens such as Hantavirus, severe acute respiratory syndrome (SARS), and bird flu should be suspected after travel to endemic areas (areas where these pathogens exist).
The
signs and symptoms of pneumonia are variable from patient to patient
and, unfortunately, cannot be used reliably to distinguish different
causes of the infection. Classically patients with pneumonia have
symptoms of cough, shortness of breath, sputum production (matter
coughed up from the respiratory area), chest pain and fever. The chest
pain of pneumonia is often pleuritic in nature, meaning there is a
sharp, stabbing pain when taking deep breaths. In 10-30% of patients,
non-respiratory complaints such as headache, muscular pain (myalgias),
fatigue, and gastrointestinal symptoms may predominate. The elderly in
particular may lack “classic findings,” – such as cough, fever, and
shortness of breath – and are more likely to present with subtle
findings such as confusion, and abdominal pain.
There
are signs, or physical exam findings that most doctors look for when
evaluating a patient for possible pneumonia. The vital signs are
important (one might say they are vital). Patients with pneumonia often
have the following:
- 80% have fever
- 70% have tachypnea (rapid breathing)
- 50% have tachycardia (fast heart rate)
Patients
suspected of having pneumonia will often have pulse oximetry performed
to measure their blood oxygen saturation. A normal value is 100% and
patients with CAP often have blood oxygen values less than 93%. When
listening to the lungs, doctors are trying to hear if patients have
focal findings, meaning abnormal sounds in one part of the lungs, but
not in others. Up to 90% of patients with pneumonia will have a focal
lung exam with “crackles,” bronchial breath sounds (a sign of
consolidated lung where breath sounds are more readily transmitted), or
rhonchi (a non-specific coarse breath sound). No exam finding is
specific for pneumonia and in many patients the lung exam findings can
be quite subtle. However, the absence of fever, tachycardia, and
tachypnea in patients significantly reduces the likelihood of CAP.
Similar to the clinical history, the physical exam in elderly patients
is neither sensitive nor specific for the diagnosis of pneumonia as in
up to 40% of cases fever may be absent.
Given
the nonspecific nature of the symptoms and signs of pneumonia, there is
no clinical feature or combination of features that adequately rules in
or out the disease. The differential diagnosis (systematic comparing
and contrasting of clinical findings for two or more potential diseases)
to be considered is broad. Common noninfectious diseases that can
present with similar signs and symptoms include:
- Congestive Heart Failure
- Chronic Obstructive Pulmonary Disease exacerbation
- Pulmonary Embolism (a blood clot blocking the lung)
- Asthma Hypersensitivity Pneumonitis (inflammation of the lung [usually of the very small airways] caused by the body's immune reaction to small air–borne particles)
There are also
other upper and lower airway infectious diseases that can mimic CAP.
Patients with acute bronchitis, a diagnosis that accounts for up to 40%
of patients evaluated for cough (vs. 5% for pneumonia), often lack high
fevers or significant hypoxia (oxygen depletion) and generally do not
benefit from antibiotics. (Take a tour of the bronchial tree, http://www.youtube.com/watch?v=HH-NmeWeJts)
Other pneumonia-like syndromes such as aspiration pneumonitis, an
inflammatory condition in the lungs resulting from inhalation of vomit
or other macro-aspirated material, will appear clinically identical to
CAP and needs to be considered in the differential diagnosis because
treatment will differ from uncomplicated CAP.
The
diagnosis of CAP requires signs and symptoms compatible with pneumonia
AND evidence of an infiltrate (abnormal substance) on chest radiograph
or chest X-ray (CXR). The findings on CXR range from lobar consolidation
(one lung lobe showing pneumonia) to “hazy infiltrates,” or both lung
lobes showing widely distributed infiltrates. Most national guidelines,
therefore, recommend that all patients with a possible diagnosis of CAP
be evaluated with a CXR.3 While this is certainly true for
most patients presenting to emergency rooms or patients admitted to the
hospital, patients in the outpatient setting, where CXR may not be
readily available, may be diagnosed and treated as having pneumonia
without a confirmatory chest radiograph. There are in fact, prediction
rules that determine the probability of patients having an abnormal CXR
if they present with certain findings. For example, one study showed
that patients presenting with symptoms consistent with pneumonia who had
all five of the following variables had a nearly 90% chance of having
an infiltrate on CXR:5
- No history of asthma
- Temperature greater than 100o F
- Heart rate greater than 100 beats / min.
- Lung exam showing crackles
- Lung exam showing decreased breath sounds
It
would not be unreasonable to treat patients with all five findings with
antibiotics even in the absence of performing a CXR. In addition,
patients who had none of these findings had less than a 5% chance of
having an infiltrate, and thus they should probably not receive
antibiotics for pneumonia.
But even the CXR is not perfect
and can miss some cases of CAP. In studies that have had patients
suspected of having pneumonia receive both a CXR and a chest computed
tomography (CT) scan, up to one third of pneumonia cases were missed on
CXR.6 Whether these “CXR negative, CT scan positive” cases
behave the same as CXR positive cases remains to be seen. It is also
true that many diseases that mimic CAP, like congestive heart failure,
can also have abnormal CXRs. Such findings make us wonder how good CXR
really is. As a result, many studies have begun to evaluate various
“biomarkers” that can be measured in the blood and provide evidence of
an infectious process, which in the setting of consistent symptoms would
suggest pneumonia. To date, C-reactive protein (CRP), procalcitonin,
and soluble triggering receptor expressed on myeloid cells (s-TREM) are
the inflammatory biomarkers that have all been evaluated in the
diagnosis of CAP. Preliminary evidence suggests they may ultimately
prove useful in differentiating infectious from noninfectious lung
processes, but routine use of these biomarkers is not currently
recommended.
Unfortunately,
the presenting signs and symptoms of pneumonia (including the CXR
appearance) cannot reliably predict the organism causing the infection.
Physicians like to know what “bug” is causing the infection to make sure
patients are on an antibiotic that covers that bug, but is not overly
powerful (which can cause side effects and increase resistance among
bacteria). This is so-called targeted therapy. The alternative is using
empiric therapy, meaning you do not know what is causing the infection
so you use an antibiotic that covers most of the likely bacteria. The
tests most often ordered to identify the infecting organism include
blood cultures, sputum analysis (gram stain and culture), and tests
directed at particular known causes such as pneumococcal urinary
antigen, legionella urinary antigen, and some viral tests (i.e., for
influenza or respiratory syncytial virus [RSV]).
Blood
cultures involve drawing several samples of blood into culture vials
that are then “grown” in the microbiology lab for two or more days. Only
around 5% of pneumonia patients will have positive blood cultures (but
up to 25% for pneumococcus) and several studies have shown that positive
findings rarely change how doctors treat the pneumonia (because these
patients are often already being treated with an antibiotic that covers
the bacteria found in the blood). In addition, cultures can sometimes
grow a “contaminant” and confuse the picture. As it seems that the
sicker patients are more likely to have positive cultures (and in sicker
patients who are more likely to harbor bacteria resistant to commonly
used antibiotics, it is more important to get the right antibiotic
started quickly), it is currently recommended that blood cultures be
performed in the following groups: all patients admitted to an ICU, a
subset of those not in the ICU (but still in the hospital) who have
certain clinical risk factors that increase the chances of having
bacteria in the bloodstream (Table 3), but NOT outpatients.3 When blood cultures are drawn, they must be drawn prior to antibiotics.
Sputum analysis by gram stain (dying the sputum with special stains to look for bacteria) and sputum culture (trying to grow bacteria in the sputum) can also help to identify a causative organism. However, sputum studies are not very sensitive (they miss some bacteria) and not very specific (they find some bacteria that just live in the sputum but are not causing the infection). Furthermore, the utility of sputum is also limited by the fact that 30% of people can’t provide a good sample and another 30% have often already had antibiotics which substantially lowers their yield. While performance is not ideal, high rates of resistance among pneumococcal isolates and the increasing rates of infection with CA-MRSA make identifying the bacteria increasingly important. National guidelines do not recommend sputum analysis for outpatients, but do recommend it for sicker patients in the ICU. Similar to blood cultures, sputum analysis in hospitalized, non-ICU patients is recommended if certain risk factors are present (Table 3).3 These risk factors increase the chance that a given patient will have an unusual or potentially drug-resistant pathogen in their sputum which would affect the choice of antibiotic for a particular patient.
Urine
antigen tests to look for a particular organism (such as pneumococcus
or legionella) can also be useful. Antigen tests detect bacterial
products in the urine that are excreted during acute infections. The
pneumococcal urinary antigen test is fairly sensitive (detects 50-80% of
infections) and quite specific (more than 90% of the time when it is
positive a patient truly has a pneumococcal pneumonia). This test may
allow for targeted, narrow-spectrum antibiotic therapy in the setting of
a positive test, and in low risk outpatients, some studies have
suggested this is an effective and safe approach. Another urine test,
Legionella urinary antigen testing, detects about 80-95% of the
community acquired cases of Legionnaire’s disease with a specificity of
90%. Because legionella bacteria tends to cause serious infections,
routine use of this test is usually limited to patients in the ICU.
There
are many other diagnostic tests that specifically look for certain
viral infections (influenza and RSV), fungal infections
(histoplasmosis), or mycobacterial diseases (tuberculosis) that can be
ordered when these infections are clinically or epidemiologically
suspected.
Who Gets Admitted to the Hospital?
Most patients with pneumonia can be safely treated at home. Deciding who needs hospitalization is one of the more difficult decisions that must be made in any patient diagnosed with CAP. The decision is usually based on several factors, including physician judgment, pneumonia severity scoring systems, and a good understanding of what the patient’s home situation is like. Patients who are very ill with a low blood oxygen saturation (less than 90%), have an active coexisting disease, have gotten worse despite treatment at home, or who cannot tolerate oral medications need to be admitted to the hospital. If none of these variables exist, use of a severity scoring system that takes into account age, coexisting or comorbid conditions (like cancer, liver disease, etc.), as well as vital sign and lab abnormalities can be used to calculate a severity score (http://pda.ahrq.gov/clinic/psi/psicalc.asp) that can help clarify which patients are most at risk. The best studied risk stratification score is the pneumonia severity index (PSI) (Figure 1).7 Use of the PSI in emergency rooms has been shown to safely identify patients who are eligible for discharge and those who require admission. In general, patients in risk classes I, II, and III can be safely managed at home, while those in risk classes IV and V require admission. However, sometimes even patients who are classified as low risk may still require hospitalization if, for example, they have unstable home situations or are frail. On the other hand, patients who are high risk due to variables like age alone or multiple comorbidities, could potentially be managed at home if they have a minor pneumonia with stable vital signs (Figure 2).8 Ultimately, while clinical decision rules like the PSI can help, they should never supersede clinical judgment.
The
mainstay of treatment for CAP is antibiotic therapy. Viral pneumonias
do not require antibiotics, but until doctors know it’s a virus, or if
it is known to be a virus but a concern about a “secondary” or
complicating bacterial infection exists, antibiotics will often be used.
Because the pathogen causing the pneumonia is identified in no more
than 50% of cases (and even when an infecting pathogen is identified it
can take several days) doctors must implement empiric antibiotic
therapy. Empiric therapy depends on the site of care (outpatient vs.
hospital ward vs. ICU) and underlying risk factors and is designed to
target the most likely infecting bacteria. Recent guidelines from the
American Thoracic Society and the Infectious Diseases Society of America
make the following recommendations for antibiotic treatment of
pneumonia3
Previously healthy patients with no antibiotic use in the past three months:
- Macrolide (Azithromycin, Clarithromycin, Erythromycin) or
- Doxycycline
Patients with comorbidities (heart, lung, liver, or kidney disease, diabetes, malignancies, immune suppressed states) or with recent antibiotic use are more at risk for DRSP (see above) and other resistant bacteria and thus stronger antibiotics are warranted:
- Respiratory Fluoroquinolone (Levofloxacin, Moxifloxacin, Gemifloxacin) or
- A Beta-Lactam (a penicillin-like drug) + a macrolide or doxycycline
Professional
society guideline recommendations for the treatment of CAP in
hospitalized patients (hospital wards and ICU) reflect the following
factors:
- Antimicrobial therapy must treat all likely pathogens that typically cause CAP including both typical and “atypical” organisms. Many studies have suggested that survival is improved when a drug targeting atypical agents (macrolides, fluoroquinolones, doxycycline) is added to a beta lactam (usually a cephalosporin) when compared to just using a beta lactam alone. It is not clear why this is so, but lacking better studies, there is enough evidence now to justify this approach in patients sick enough to be hospitalized.
- All empiric therapy must cover DRSP effectively. Beta lactams (like Ceftriaxone, Cefotaxime, and Ampicillin-Sulbactam) fill this need and are included in most empiric regimens
- Risk factors for specific bacteria such as CA-MRSA and Pseudomonas aeruginosa (a particularly virulent type of bacteria) need to be considered when choosing therapy
- Antibiotic therapy should be tailored if diagnostic tests show which bacteria is causing the infection
- Antibiotics should be given as quickly as possible once it is clear that a patient has pneumonia. There are current “quality performance targets” for hospitals that require all patients with CAP be given antibiotics within four hours of arrival to the hospital. While some studies suggest four hours is better than say eight or 10 hours, hurrying to give antibiotics before the diagnosis of pneumonia has been confirmed has resulted in “non-pneumonia” patients being treated unnecessarily with antibiotics.
Initial empiric antibiotic therapy recommendations for hospitalized patients are shown in the table below (Table 4).
There
are no large trials that clarify how long we should treat pneumonia.
For routine, uncomplicated pneumonia, there is little evidence that
treatment beyond seven days is necessary. There are certain bacteria
that require longer treatment if they are isolated. For example, MRSA or
P. aeruginosa are usually treated for 14 days and legionella may
require treatment up to 21 days depending on the severity of illness.
Patients who develop infectious complications of their pneumonia – such
as an empyema (an infection of the sack that surrounds the lungs) – also
require a longer treatment. In the case of an empyema, drainage of the
infection is also required.
In hospitalized patients most antibiotics are given intravenously (I.V.) during initial treatment. As patients improve, a switch to oral therapy can be initiated. Several studies have suggested that once patients meet the following criteria for at least 24 hours, a switch to oral therapy can safely occur:9
- Temperature less than or equal to 100 F
- Heart Rate less than or equal to 100
- Respiratory Rate less than or equal to 24
- Blood Pressure greater than or equal to 90 mm Hg systolic
- Oxygen saturation (without supplemental oxygen) greater than 90%
- Able to take oral medications
Once a patient is on oral therapy, discharge from the hospital is usually close at hand. In addition to meeting the oral therapy criteria above, patients should have no evidence of active co-morbid disease, a normal mental status (no confusion), and should have safe, appropriate outpatient follow-up. Patients should realize that while antibiotics are not continued for very long, many symptoms of the pneumonia can persist for quite some time even after discharge from the hospital. For example, the cough associated with pneumonia may last up to four to six weeks, well beyond the usual duration of hospitalization or antibiotic treatment.
- Prevention of pneumonia has traditionally relied on vaccination of “at risk” individuals with the 23-valent polysaccharide pneumococcal pneumonia vaccine (Pneumovax). This vaccine covers the 23 serotypes of S. Pneumoniae that cause 85-90% of the invasive pneumococcal infections in the United States. Unfortunately the vaccine, when given to elderly patients or patients with comorbidities, has not been shown to improve mortality or prevent pneumonia.10 It may, however, prevent invasive disease (prevents the bacteria from getting into the bloodstream) in patients who develop a pneumococcal infection like pneumonia. For this reason, the CDC recommends pneumococcal vaccination in eligible patients http://www.immunize.org/immschedules/immschedule_adult.pdf Interestingly, it appears that vaccination of children against pneumococcal disease (with a 7-valent conjugate vaccine) has been successful in reducing the rate of pneumococcal disease in adults, especially those over the age of 65. This is likely due to the fact that children are often the reservoirs for pneumococcus and then transmit the bacteria to adults.
- Seasonal influenza (flu) vaccination has clearly been shown to decrease influenza-related illness in high risk populations such as the elderly. In a large study of patients over the age of 65, vaccination against influenza prevented pneumonia, hospitalizations, and death.11 The CDC also recommends influenza vaccination for all patients over 50 years of age, patients with comorbidities, and health care workers.
- Smokers are at increased risk for invasive pneumococcal disease as well as pneumonia. It obviously follows that efforts to stop smoking will help prevent pneumonia and its complication. http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=22931
- As suggested in the section on “How do you get pneumonia?” potent gastric acid suppressing drugs such as the proton pump inhibitors may increase the risk of microaspiration of infected secretions down into the lungs thus causing pneumonia. Efforts to avoid unnecessary use of these drugs are therefore warranted.
1.
Sharpe BA, Flanders SA. Community-acquired pneumonia: a practical
approach to management for the hospitalist. J Hosp Med 2006;1:177-90.
2.
Laheij RJ, Sturkenboom MC, Hassing RJ, Dieleman J, Stricker BH, Jansen
JB. Risk of community-acquired pneumonia and use of gastric
acid-suppressive drugs. JAMA 2004;292:1955-60.
3. Mandell
LA, Wunderink RG, Anzueto A, et al. Infectious Diseases Society of
America/American Thoracic Society consensus guidelines on the management
of community-acquired pneumonia in adults. Clin Infect Dis 2007;44
Suppl 2:S27-72.
4. Shefet D, Robenshtock E, Paul M,
Leibovici L. Empiric antibiotic coverage of atypical pathogens for
community acquired pneumonia in hospitalized adults. Cochrane Database
Syst Rev 2005:CD004418.
5.
Metlay JP, Kapoor WN, Fine MJ. Does this patient have
community-acquired pneumonia? Diagnosing pneumonia by history and
physical examination. Jama 1997;278:1440-5.
6. Syrjala H,
Broas M, Suramo I, Ojala A, Lahde S. High-resolution computed tomography
for the diagnosis of community-acquired pneumonia. Clin Infect Dis
1998;27:358-63.
7. Fine MJ, Auble TE, Yealy DM, et al. A
prediction rule to identify low-risk patients with community-acquired
pneumonia. N Engl J Med 1997;336:243-50.
8. Halm EA, Metlay JP, Singer DE, Fine MJ. Community-acquired pneumonia. N Engl J Med 1996;334:862; discussion -3.
9.
Halm EA, Fine MJ, Marrie TJ, et al. Time to clinical stability in
patients hospitalized with community- acquired pneumonia: implications
for practice guidelines. Jama 1998;279:1452-7.
10. Flanders
S. Pneumococcal vaccination prior to hospital discharge. Making Health
Care Safer: A Critical Analysis of Patient Safety Practices Shojania KG,
Duncan BW,
McDonald KM, Wachter RM, editors Evidence Report
/ Technology Assessment No 43, AHRQ Publication No 01-E058; July 2001
Full report available at http://wwwahrqgov2001.
11. Nichol
KL, Nordin J, Mullooly J, Lask R, Fillbrandt K, Iwane M. Influenza
vaccination and reduction in hospitalizations for cardiac disease and
stroke among the elderly. N Engl J Med 2003;348:1322-32.