Community-acquired pneumonia (CAP) ...

Community-acquired pneumonia (CAP) affects approximately 45 million adults in the United States annually. (1) About individual third of these adults require hospitalization. (1) The mortality rate among hospitalized patients with CAP varies each year and can reach 35 percent (2) While Streptococcus pneumoniae causes up to 70 percent of CAP cases, atypical pathogens are responsible for 30 to 40 percent of cases (3) and may be copathogens in other cases. equable with a knowledge of more [i]or[/i] less of the common characteristics of infections with atypical organisms (Table 1) (4) determining the specific pathogen onward the basis of clinical, radiologic, and laboratory findings is difficult and usually done retrospectively, if at all.

Atypical Pathogens

MYCOPLASMA PNEUMONIAE

Mycoplasma pneumoniae causes a wide range of respiratory infections, including pneumonia, tracheobronchitis, and upper respiratory tract infection. alone 3 to 10 percent of bodily forms infected with M. pneumoniae bring out pneumonia. (5) Because M. pneumoniae infection becomes more universal with increasing age, it is particularly important to consider this agent in somewhat old patients. (6)

M pneumoniae infection flash on the minds throughout the year but can cause periodic outbreaks within small communities. Transmission is at person-to-person contact, and infection spreads slowly most numerous often within closed populations (eg households, instructs businesses).

M. pneumoniae is the pathogen greatest in quantity often associated with atypical pneumonia. attack is insidious, over several days to a week. Constitutional symptoms, which usually are ready include headache exacerbated by a cough malaise,myalgias, and sore throat. The cough is usually dried paroxysmal, and worse at night.

The clinical course of pneumonia caused by way of M. pneumoniae is usually mild and self-limited. The mortality rate is approximately 14 percent (2) However, pulmonary complications can be significant and include effusion, empyema, pneumothorax, and respiratory distress syndrome

M pneumoniae infection may be associated with several extrapulmonary manifestations. Skin manifestations include erythema multiforme, erythema nodosum, maculopapular and vesicular eruptions, and urticaria. Neurologic derangements include aseptic meningitis, cerebral ataxia, encephalitis, Guillain-Barre syndrome and transverse myelitis. The production of biting agglutinins can result in hemolytic anemia, especially when M pneumoniae titers are high. Finally, complications as it was as myocarditis, pancreatitis, pericarditis, and polyarthritis can occur

CHLAMYDIA PNEUMONIAE

Chlamydia pneumoniae is an obligate intracellular organism capable of persistent latent infection. Humans are the and nothing else known reservoir. Transmission results from contact with respiratory secretions, with an incubation period of several weeks.

by the agency of the age of 20 years, common half of persons in the United States have detectable plains of antibody to C. pneumoniae. (7) The antibody is not past nor future in 75 percent of somewhat old persons.7 C. pneumoniae infection is more likely to arise in older patients with comorbid diseases than in those who are otherwise healthy. (8)

Patients with C pneumoniae infection oftentimes present with sore throat, headache, and a cough that can persist for month if treatment is not initiated early. (9) Sputum is usually scant or nonexistent, and a low-grade agitation is usually present. Chest radiographs take care of to show less extensive infiltrates than are seen with other causes of pneumonia, although significant infiltrates have been reported. (10)

greatest in quantity cases of C. pneumoniae infection are mild, unless severe disease can occur, necessitating admission to an intensive care unit. The mortality rate has been estimated to be 9 percent and death usually is associated with secondary infection and underlying comorbid disease. (2)

LEGIONELLA PNEUMOPHILA

Like C pneumoniae, Legionella species are intracellular organisms. Legionella pneumophila is the principally pathogenic species, and several serotype have been identified. Serotype 1 has been associated with greatest in quantity reported human cases of pneumonia caused by means of L. pneumonphila. (11)

Infection offers from exposure to legionellae organisms in the environment. Person-to-person spread has not been reported. Legionellae are erect most commonly in freshwater and man-made water a whole s The pathogens also can be build in moist soil, especially near streams and pond Man-made hypothesiss for heating and cooling water can be prime environments for the proliferation of legionellae, because of conditions in the same state [i]or[/i] condition as temperatures between 32[degrees]C (896[degrees]F) and 45[degrees]C (113[degrees]F) stagnation of water, and the demeanor of scale sediment and amebas. (12) Condenser cooling towers, respiratory therapy equipment, showers, water faucets, and whirlpools have been associated with outbreaks of legionellosis. (13)

Risk factors for the progression in a continuously ascending gradation of legionellosis include overnight stays outside the residence recent home plumbing work, renal or liver failure, diabetes, malignancy, and other conditions that compromise the immune combination of parts to form a whole (14) Legionnaires' disease may at hand with a wide spectrum of symptoms ranging from mild cough and low-grade febrile affection to high fever, altered mental status, and respiratory failure. (15) Nonspecific symptoms may meet the eye early in the disease and include headache, muscle aches, anorexia, and malaise. (15) Diarrhea and other gastrointestinal symptoms are existing in 20 to 40 percent of cases. (15) Leukocytosis is a universal laboratory finding, and the sputum Gram stain repeatedly shows an abundance of inflammatory solitary abode; squalids without a predominance of organisms. (11)