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Community acquired pneumonia

Pneumonia in individuals who become ill outside the hospital or within 48 hours of admission.

The leading infectious cause of hospitalization and death in developed countries and worldwide.

The most common infection leading to hospitalization and death in all age groups, especially the elderly.

Annual cost in excess of $17 billion in the US.

Mortality among hospitalized patients still high, especially in those with severe pneumonia and those who experience treatment failure, which is observed in 10-20% of patients.

Incidence requiring hospitalization is highest among the oldest adults.

Annual incidence of CAP requiring hospitalization 24.8 cases per 10,000 adults (EPIC).

Advanced age, the presence of altered mental status and and vital sign abnormalities increase risk of mortality.

Specific pathogens are not detected in most patients with CAP.

The organisms responsible as noted are usually not confirmed as noted, but S. Pneumoniae and mycoplasma pneumoniae are common causative pathogens.

Other pathogens include H. Influenzae, Moraxella catarrhalis,Chlamydophilia pneumonia, Legionella species, Staphylococcus aureus, and anaerobic mouth organisms.

Viral pathogens are common in CAP, but are considered to have bacterial pneumonia at the time of admission due to the absence of widely testing for the full range of pathogens

As a result of the above initiation of empirical antibiotic therapy covering the most likely bacterial pathogens is the standard of care.

Patients greater than 65 years hospitalized with CAP have a overall mortality in 30 days of 6.5%.

WHO estimates pneumonia is the most common infectious cause of death in the world, the third most common cause overall, with almost 3 1/2 million deaths yearly.

Accounts for approximately 5.6 million cases and 1 million hospitalizations yearly in the U.S.

Estimated 50,000 this into thousand and 10 attributed to pneumonia and this is probably an under estimate.

Medical costs exceeding $10 billion in 2011 for CAP.

Affects approximately 1% of adults annually.

Annual incidence of 12 episodes per 1000 persons.

More than 900,000 cases in adults over the age of 65 years annually with an incidence of 8.2 cases per 1000 person-years for individuals 65-69 years of age, 27.9 cases per 1000 persons-years for patients aged 75-79 years and 52.3 cases per 1000 person-years for those greater than 85 years of age.

Estimated incidences of hospitalization for CAP among adults 50-64 years, 65-79 years, and 80 years of age or older ARE approximately 4, 9, and 25 times as high, respectively, as the incidence among adults 18-49 years of age ( Etiology of Pneumonia in the Community (EPIC).

In the above study of 2488 patients pathogens were found in 38% with viruses detected and 27% and bacteria and 14%.

In the above study human rhinovirus, Influenza virus, and S. pneumoniae with the most common detected pathogens, with the highest burden occurring among older individuals.

In children pathogens are detected in approximately 80% of cases of hospitalized patients with CAP.

Amoxicillin is widely recommended as the first line antibiotic for CAP in young children.

Among children with CAP discharged from an ED or hospital a lower dose of outpatient oral amoxicillin was not inferior to a higher dose, and a three day duration was not inferior to seven days, with regard to need for antibiotic re-treatment.

 

Low percentage of diagnosis of pathogens possibly related to the inability to obtain lower respiratory tract specimens, the use of antibiotics before specimen collection, insensitive diagnostic tests, lack of testing for other types of pathogens, unidentified pathogens, and possible non-infectious causes.

For individuals greater than 85 years of age approximately 1 in 20 will have an episode of CAP each year.

Elderly often present with few classic respiratory signs and symptoms but frequently have delirium, progressive confusion and falling episodes.

Current diagnostic tests do not detect the pathogen in the majority of patients.

Respiratory viruses are detected more frequently than bacteria in acquired CAP hospitalizations among the US adults (Jain S et al).

Diagnosis is usually not difficult in patients who do not have underlying cardiopulmonary disease.

Findings include fever, chills, leukocytosis, cough, sputum production, shortness of breath, chest pain, abnormal pulmonary clinical findings, a new or changed lung infiltrate on chest x-ray are usual indications of community acquired pneumonia.

Diagnosis in patients with pulmonary fibrosis, other chronic infiltrative lung diseases, lung cancer, or congestive heart failure is difficult.

Diagnostic delay is common in patients with atypical presentations and you have comorbidities as noted above.

Chest x-ray infiltrates may show only subtle changes and a radiologist may miss findings in 15% of cases, and two radiologists reading the same chest x-ray disagree in 10% of cases.

Associated with a high incidence of silent aspiration in the elderly.

A leading cause of morbidity and mortality worldwide.

Cardiac complications occur in as many as 27% of patients hospitalized for CAp.

Cardiac complications are responsible for one third of clinical failures of treatment of CAP.

Excessive host inflammatory response is associated with treatment failure during ICU admission and mortality.

Cardiac complications are the direct or underlying cause of death and one fourth of CAP associated fatalities.

Approximately 15% of patients require hospitalization.

Chest x-ray is considered the standard for diagnosing the presence of pneumonia.

Most common cause Streptococcus pneumoniae.

Streptococci implicated in nearly 500,000 cases/year.

Approximately 10% of patients over the age of 64 admitted to the hospital die before discharge and many more die within one month of discharge.

Approximately 40% of such infections in the elderly require hospitalization and a mortality rate of 40% occurring within 1 year has been reported.

Most patients treated as outpatients.

Death due to pneumonia in the elderly as high as 20% (Riquelme).

As many associated 59% of elderly patients are readmitted within 18 months.

Overall case-fatality rate of about 5%.

Mortality substantially greater, about 13.6%-among hospitalized patients.

Cardiac complications that develop in CAP patients result in an increase short-term mortality by 60-200%.

Risk factors with increased mortality: age >65 years, COPD, diabetes mellitus, chronic renal failure, congestive heart failure, chronic liver disease, suspicion of aspiration, altered mental status, postsplenectomy, chronic alcohol abuse, malnutrition, respiratory rate >30, diastolic blood pressure < 60 mm Hg, systolic blood pressure <90 mm Hg, temperature >38.3?C, extrapulmonary sites of infection, WBC <4000mm3, Pao2 < 60 mm Hg, Pco2> 50 mm Hg, need for mechanical ventilation, abnormal renal function, rapid radiographic spreading, presence of a pleural effusion, hematocrit < 30%, evidence for sepsis and evidence for DIC.

The Pneumonia severity index (PSI) uses a scoring system to predict 30 day mortality and assignment of care as an in or out-patient with 5 risk classes I-V based on 19 variables in demographic factors, comorbid processes, physical examination findings and laboratory findings.

PSI includes factors such as gender, nursing home resident, presence of altered mental status, types of co morbid illnesses, respiratory rate > 30/min, blood pressure less than 90 mm HG, temperature <35 degrees centigrade or >40 degrees centigrade, pulse rate >125 beats/min, pH <7.35, serum sodium less than 130 mEq/L, BUN > 0 mm/L, hematocrit <30%, PA02 < 60 mm HG and the presence of pleural effusion.

Bacteremia caused by Streptococcus pneumoniae documented in up to 26% of hospitalized patients.

Bacteremia caused by Streptococcus pneumoniae associated with a mortality of 19-28%.

Blood cultures should be done in only the sickest patients with community acquired pneumonia, as routine blood cultures for such patients who are hospitalized have limited utility and false-positive results lead to inappropriate antimicrobial use and longer hospital stays.

The Infectious Diseases Society of America/American Thoracic Society guidelines recommend empirical antibiotics for all hospitalized patients that covers most common typical as well as atypical pathogens.

It is recommended that the first antibiotic dose be administered within six hours after presentation for CAP.

Current recommendations for the duration of antibiotic therapy is 5-7 days for CAP.

Retrospective studies suggest a combination of anabiotics is associated with better outcomes, especially with lower mortality and particularly in patients with severe disease.

Macrolide antibiotics are frequently identified as the key component of combination treatment regimens.

Recommendation for patients who have hypotension is that antibiotics should be given within one hour of presentation.

In patients with septic shock and CAP, a decrease in survival rates of 8% occurs for each hour of delay in the administration of antibiotics (Kumar A et al ).

Fluoroquinolone monotherapy or Beta-lactam plus macrolide combination recommended for hospitalized patients.

Infectious Diseases Society of America and American Thoracic Society guidelines recommend either a beta-lactam plus a macrolide or a respiratory fluoroquinolone.

In a randomized crossover trial patients with suspected CAP admitted to non-ICU wards a strategy of empirical treatment with beta-lactam monotherapy was not inferior to strategies with the beta-lactam-macrolide combination or fluoroquinolone monotherapy with regard to 90 day mortality(Postma DF et al).

The administration to hospitalized patients of either a respiratory fluoroquinolone or the combination of the second-generation or third-generation cephalosporin and a macrolide indicate decrease mortality and length of hospital stay.

Three decisions are made simultaneously when a patient presents with CAP: the choice of antibiotics, the extent of testing to determine the cause, and location of treatment site.

The key initial therapy is to adequately cover for Streptococcus pneumonia and the atypical bacterial pathogens such as mycoplasma, chlamydophylia, and Legionella.

Outpatient coverage of atypical bacterial pathogens is required, especially for young adults, in the agents of choice are macrolides, doxycycline and fluoroquinolones.

For mild to moderate CAP in hospitalized patients antibiotics for 3-5 days is equivalent to longer courses of therapy (Uranga A et al).

Streptococcal pneumonia is still the most common cause of severe community acquired pneumonia requiring ICU admission, the combination of a cephalosporin with either a fluoroquinolone or macrolide is recommended.

In the above setting, results with macrolides may be associated with better outcomes.

Initial intravenous antibiotic therapy may be switched to oral therapy once the patient shows clinical stability even if bacteremia caused by Streptococcus pneumoniae was initially documented.

Sputum culture, Gram stain and pretreatment blood culture recommended for patients hospitalized for CAP but in general treatment is empiric and based on patients age, underlying illness, clinical history and radiographic appearance.

After extensive testing a causative agent is not determined in 50% of cases.

Mortality low in patients who can be managed as and outpatient but may be 25% or greater in hospitalized patients, especially if they require admission to the ICU.

Evaluation for ambulatory patients include a CXR, CBC and chemistries.

Evaluation for hospitalized patients include CXR, CBC, chemistries, pulse oximetry/arterial blood gas, and blood cultures.

Evaluation for patients with severe CAP include all the above plus Gram stain, sputum culture and Legionella antigen studies.

Differential diagnosis with an abnormal chest x-ray includes: congestive heart failure with associated viral syndrome, aspiration pneumonia, pulmonary infarction, exacerbation of fibrosis, exacerbation of bronchiectasis, eosinophilic pneumonia, hypersensitivity pneumonitis, pulmonary vasculitis, and cocaine induced lung injury.

Severe community acquired pneumonia is associated is a major cause of mortality and despite effective antibiotic therapy 12-36% of patients admitted to the ICU die within a short period of time.

Patients with risk class V for Pneumonia severity Index also have a high mortality risk.

Increased serum levels of cytokines IL-6, IL-8, and IL-10 in severe community acquired pneumonia.

Excess serum levels of IL-6 and IL-10 are associated with high mortality rate among patients with community acquired pneumonia.

Use of corticosteroids remains controversial except in patients patients with severe pneumonia and high inflammatory responses, defined as CRP level greater than 150 mg/L at admission.

In the above situation that acute administration of methylprednisolone is associated with less treatment failure and lower inflammatory response.

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