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==Overview==
==Overview==


Complications including [[sepsis]], [[respiratory failure]], [[pleural effusion]], and [[empyema]] may occur despite appropriate antibiotic treatment. Complications are associated with bacterial pneumonia more frequently than viral pneumonia.
Complications, including [[sepsis]], [[respiratory failure]], [[pleural effusion]], and [[empyema]], may occur despite appropriate antibiotic treatment. Complications are associated with bacterial pneumonia more frequently than they are with viral pneumonia. Most types of bacterial pneumonia can be cured within one to two weeks of appropriate medication. Viral pneumonia may last longer, and mycoplasmal pneumonia may take four to six weeks to resolve completely. The eventual outcome of an episode of pneumonia depends on how ill the person is when he or she is first diagnosed.
 
==Natural History==
*Pneumococcal pneumonia is the most common clinical presentation of pneumococcal disease amongst adults, although pneumonia without bacteremia or empyema is not considered to be “invasive” disease. <ref name=cdc> {{cite web|url=http://www.cdc.gov/pneumococcal/clinicians/clinical-features.html| title=CDC Pneumococcal Disease Clinical Features}} </ref>
*The incubation period of pneumococcal pneumonia is short, about 1 to 3 days. <ref name=cdc/>
*Symptoms generally include an abrupt onset of fever and chills or rigors. <ref name=cdc/>
*Typically there is a single rigor; repeated shaking chills are uncommon. <ref name=cdc/>
*Other common symptoms include: pleuritic chest pain, cough productive of mucopurulent, rusty sputum, dyspnea, tachypnea, hypoxia, tachycardia, malaise, and weakness. Nausea, vomiting, and headaches occur less frequently.<ref name=cdc/>
*Transmission of Streptococcus pneumoniae occurs as a result of direct person-to-person contact via respiratory droplets and by autoinoculation in persons carrying the bacteria in their upper respiratory tract. <ref name=cdc/>
*The pneumococcal serotypes most often responsible for causing infection are those that are most frequently found in carriers.<ref name=cdc/>


==Complications==
==Complications==


===Sepsis===
===Pleural Effusion and Empyema===


* [[Sepsis]] most often occurs with [[bacterial pneumonia]], with ''[[Streptococcus pneumoniae]]'' as the most common etiology.
* Community-acquired pneumonia may be complicated by parapneumonic [[pleural effusion]]s. [[Thoracentesis]] and [[pleural fluid]] analysis should be performed.


* Individuals with [[sepsis]] require hospitalization in an intensive care unit. They often require medications and intravenous fluids to keep their [[blood pressure]] from going too low. [[Sepsis]] can cause liver, kidney, and heart damage among other organ dysfunctions.
* [[Empyema]] may occur if there is local formation of pus in the pleural cavity; this requires drainage in addition to antibiotic therapy.


===Respiratory Failure===
===Abscess===


* Non-invasive maneuvers such as a [[bilevel positive airway pressure]] machine may be used for respiratory support.
* Intraparenchymal [[abscess]]es (with or without loculation) may be seen in [[aspiration pneumonia]]. They are often primarily [[Anaerobic organism|anaerobic]] or polymicrobial.


* Otherwise, [[intubation]] with [[ventilator|mechanical ventilation]] may be required.
===Sepsis and Septic Shock===


===Pleural Effusion and Empyema===
* [[Sepsis]] most often occurs with [[bacterial pneumonia]], with ''[[Streptococcus pneumoniae]]'' as the most common etiology.


* [[Pleural effusion]] may be complicated with community-acquired pneumonia. [[Thoracentesis]] and [[pleural fluid]] analysis should be performed.
===Respiratory Failure===
* Patients at the opposite ends of the age spectrum are at a high risk of respiratory failure.


* [[Empyema]] may occur if there is local formation of pus in the pleural cavity which requires drainage in addition to antibiotic therapy.
* Non-invasive maneuvers, such as a [[bilevel positive airway pressure]] (BI-PAP) machine, may be used for respiratory support. Otherwise, [[intubation]] with [[ventilator|mechanical ventilation]] may be required.


===Abscess===
* [[Pneumonia]] may be complicated by [[acute respiratory distress syndrome|acute respiratory distress syndrome (ARDS)]], which results from a combination of infection and inflammatory response.


* [[Abscess]] with or without loculation, typically seen in [[aspiration pneumonia]], is often caused by [[Anaerobic organism|anaerobic bacteria]] and polymicrobial.
==Prognosis and Mortality==


* Antibiotics usually suffice to treat abscesses. Drainage may be considered for non-responders.
With treatment, most types of bacterial pneumonia can be cured within one to two weeks. Viral pneumonia may last longer, and mycoplasmal pneumonia may take four to six weeks to resolve completely. The eventual outcome of an episode of pneumonia depends on how ill the person is when he or she is first diagnosed.
 
===Respiratory and Circulatory Failure===


Because pneumonia affects the lungs, often people with pneumonia have difficulty breathing, and it may not be possible for them to breathe well enough to stay alive without support. Non-invasive breathing assistance may be helpful, such as with a [[bilevel positive airway pressure]] machine. In other cases, placement of an [[endotracheal tube]] (breathing tube) may be necessary, and a [[Medical ventilator|ventilator]] may be used to help the person breathe.  
In the United States, about one out of every twenty people with [[pneumococcal pneumonia]] will die.<ref>http://www.kidshealth.org/parent/infections/bacterial_viral/pneumonia.html</ref> In cases where pneumonia progresses to blood poisoning ([[bacteremia]]), one of every five will die. The death rate (or [[Mortality rate|mortality]]) also depends on the underlying cause of the pneumonia. Pneumonia caused by ''Mycoplasma'', for instance, is associated with little mortality. However, about half of the people who develop methicillin-resistant ''[[Staphylococcus aureus]]'' (MRSA) pneumonia while on a ventilator will die.<ref name=combes>Combes A, Luyt CE, Fagon JY, Wollf M, Trouillet JL, Gibert C, Chastre J; PNEUMA Trial Group. Impact of methicillin resistance on outcome of Staphylococcus aureus ventilator-associated pneumonia.'' Am J Respir Crit Care Med''. 2004 Oct 1;170(7):786-92. PMID 15242840</ref> In regions of the world without advanced health care systems, pneumonia is even deadlier. Limited access to clinics and hospitals, x-rays, antibiotic choices, and inability to treat underlying conditions will inevitably lead to higher rates of death from pneumonia.


Pneumonia can also cause respiratory failure by triggering [[acute respiratory distress syndrome]] (ARDS), which results from a combination of infection and inflammatory response. The lungs quickly fill with fluid and become very stiff. This stiffness, combined with severe difficulties extracting oxygen due to the alveolar fluid, creates a need for mechanical ventilation.
* Individuals who are treated for CAP outside of the hospital have a mortality rate of less than 1%.
[[Image:Pleural effusion.jpg|200px|thumb|'''Pleural effusion'''. Chest x-ray showing a pleural effusion. The A arrow indicates "fluid layering" in the right chest. The B arrow indicates the width of the right lung. The volume of useful lung is reduced because of the collection of fluid around the lung.]]


[[Sepsis]] and [[septic shock]] are potential complications of pneumonia. Sepsis occurs when microorganisms enter the bloodstream and the [[immune system]]responds by secreting [[cytokines]]. Sepsis most often occurs with [[bacterial pneumonia]]; ''Streptococcus pneumoniae'' is the most common cause. Individuals with sepsis or septic shock need hospitalization in an [[intensive care unit]]. They often require [[intravenous fluid]]s and medications to help keep their blood pressure from dropping too low. Sepsis can cause [[liver]], [[kidney]], and [[heart]] damage, among other problems, and it often causes death.
* [[Fever]] typically responds in the first two days of therapy and other symptoms resolve in the first week.


===Pleural Effusion, Empyema, and Abscess===
* The CXR, however, may remain abnormal for at least a month, even when CAP has been successfully treated.


Occasionally, microorganisms infecting the lung will cause fluid (a [[pleural effusion]]) to build up in the space that surrounds the lung (the [[pleural cavity]]). If the microorganisms themselves are present in the pleural cavity, the fluid collection is called an [[empyema]]. When pleural fluid is present in a person with pneumonia, the fluid can often be collected with a needle ([[thoracentesis]]) and examined. Depending on the results of this examination, complete drainage of the fluid may be necessary, often requiring a [[chest tube]]. In severe cases of empyema, [[Decortication|surgery]] may be needed. If the fluid is not drained, the infection may persist, because antibiotics do not penetrate well into the pleural cavity.
* Amongst individuals who require hospitalization, the mortality rate averages 12% overall, but it is as much as 40% in people who have bloodstream infections or require intensive care.{{ref|Woodhead}}


Rarely, bacteria in the lung will form a pocket of infected fluid called an [[abscess]]. Lung abscesses can usually be seen with a chest x-ray or chest CT scan. Abscesses typically occur in [[aspiration pneumonia]] and often contain several types of bacteria. Antibiotics are usually adequate to treat a lung abscess, but sometimes the abscess must be drained by a [[surgery|surgeon]] or [[Interventional radiology|radiologist]].
==Prognosis==
* Individuals who are treated for CAP outside of the hospital have a mortality rate less than 1%.
* Fever typically responds in the first two days of therapy and other symptoms resolve in the first week.
* The x-ray, however, may remain abnormal for at least a month, even when CAP has been successfully treated.
* Among individuals who require hospitalization, the mortality rate averages 12% overall, but it is as much as 40% in people who have bloodstream infections or require intensive care.{{ref|Woodhead}}
* When CAP does not respond as expected, there are several possible causes.
* When CAP does not respond as expected, there are several possible causes.
** A complication of CAP may have occurred or a previously unknown health problem may be playing a role.
** Additional causes include inappropriate antibiotics for the causative organism (such as drug resistant ''[[Streptococcus pneumoniae]]'', a previously unsuspected microorganism (such as [[tuberculosis]]), or a condition which mimics CAP (such as [[Wegener's granulomatosis]]).
** Additional testing may be performed and may include additional radiologic imaging (such as a [[Computed tomography|computed tomography scan]]) or a procedure such as a [[bronchoscopy]] or lung [[biopsy]].
==Prognosis and Mortality==


With treatment, most types of bacterial pneumonia can be cured within one to two weeks. Viral pneumonia may last longer, and mycoplasmal pneumonia may take four to six weeks to resolve completely. The eventual outcome of an episode of pneumonia depends on how ill the person is when he or she is first diagnosed.
:* A complication of CAP may have occurred or a previously unknown health problem may be playing a role.


In the United States, about one of every twenty people with [[pneumococcal pneumonia]] will die.<ref>http://www.kidshealth.org/parent/infections/bacterial_viral/pneumonia.html</ref> In cases where the pneumonia progresses to blood poisoning ([[bacteremia]]), one of every five will die. The death rate (or [[Mortality rate|mortality]]) also depends on the underlying cause of the pneumonia. Pneumonia caused by ''Mycoplasma'', for instance, is associated with little mortality. However, about half of the people who develop methicillin-resistant''Staphylococcus aureus'' ([[MRSA]]) pneumonia while on a ventilator will die.<ref name=combes>Combes A, Luyt CE, Fagon JY, Wollf M, Trouillet JL, Gibert C, Chastre J; PNEUMA Trial Group. Impact of methicillin resistance on outcome of Staphylococcus aureus ventilator-associated pneumonia.'' Am J Respir Crit Care Med''. 2004 Oct 1;170(7):786-92. PMID 15242840</ref> In regions of the world without advanced health care systems, pneumonia is even deadlier. Limited access to clinics and hospitals, limited access to x-rays, limited antibiotic choices, and inability to treat underlying conditions inevitably leads to higher rates of death from pneumonia.
:* Additional causes include: inappropriate antibiotics for the causative organism (such as drug resistant ''[[Streptococcus pneumoniae]]'', a previously unsuspected microorganism (such as [[tuberculosis]]), or a condition which mimics CAP (such as [[Wegener's granulomatosis]]).
===Clinical Prediction Rules===
Clinical prediction rules have been developed to more objectively prognosticate outcomes in pneumonia. These rules can be helpful in deciding whether or not to hospitalize the person.


* '''[[Pneumonia severity index|Pneumonia Severity Index]]'''<ref name=fine>Fine MJ, Auble TE, Yealy DM, Hanusa BH, Weissfeld LA, Singer DE, Coley CM, Marrie TJ, Kapoor WN. A prediction rule to identify low-risk patients with community-acquired pneumonia. ''N Engl J Med''. 1997 Jan 23;336(4):243–250. PMID 8995086</ref>
:* Additional testing may be performed and may include radiologic imaging (such as a [[Computed tomography|computed tomography scan]]) or a procedure such as a [[bronchoscopy]] or lung [[biopsy]].
 
* '''[[CURB-65]]''', which takes into account the severity of symptoms, any underlying diseases, and age.<ref name="pmid12728155">{{cite journal |author=Lim WS, van der Eerden MM, Laing R, ''et al'' |title=Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study |journal=Thorax |volume=58 |issue=5 |pages=377-82 |year=2003 |pmid=12728155 |doi=}}</ref>


==References==
==References==
{{Reflist|2}}
{{Reflist|2}}
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{{WS}}


[[Category:Needs content]]
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[[Category:Disease]]
[[Category:Disease]]
[[Category:Pulmonology]]
[[Category:Pulmonology]]
[[Category:Infectious disease]]
[[Category:Pneumonia|Pneumonia]]
[[Category:Pneumonia|Pneumonia]]
[[Category:Emergency medicine]]
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Latest revision as of 21:02, 29 July 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Chetan Lokhande, M.B.B.S [2]

Overview

Complications, including sepsis, respiratory failure, pleural effusion, and empyema, may occur despite appropriate antibiotic treatment. Complications are associated with bacterial pneumonia more frequently than they are with viral pneumonia. Most types of bacterial pneumonia can be cured within one to two weeks of appropriate medication. Viral pneumonia may last longer, and mycoplasmal pneumonia may take four to six weeks to resolve completely. The eventual outcome of an episode of pneumonia depends on how ill the person is when he or she is first diagnosed.

Natural History

  • Pneumococcal pneumonia is the most common clinical presentation of pneumococcal disease amongst adults, although pneumonia without bacteremia or empyema is not considered to be “invasive” disease. [1]
  • The incubation period of pneumococcal pneumonia is short, about 1 to 3 days. [1]
  • Symptoms generally include an abrupt onset of fever and chills or rigors. [1]
  • Typically there is a single rigor; repeated shaking chills are uncommon. [1]
  • Other common symptoms include: pleuritic chest pain, cough productive of mucopurulent, rusty sputum, dyspnea, tachypnea, hypoxia, tachycardia, malaise, and weakness. Nausea, vomiting, and headaches occur less frequently.[1]
  • Transmission of Streptococcus pneumoniae occurs as a result of direct person-to-person contact via respiratory droplets and by autoinoculation in persons carrying the bacteria in their upper respiratory tract. [1]
  • The pneumococcal serotypes most often responsible for causing infection are those that are most frequently found in carriers.[1]

Complications

Pleural Effusion and Empyema

  • Empyema may occur if there is local formation of pus in the pleural cavity; this requires drainage in addition to antibiotic therapy.

Abscess

Sepsis and Septic Shock

Respiratory Failure

  • Patients at the opposite ends of the age spectrum are at a high risk of respiratory failure.

Prognosis and Mortality

With treatment, most types of bacterial pneumonia can be cured within one to two weeks. Viral pneumonia may last longer, and mycoplasmal pneumonia may take four to six weeks to resolve completely. The eventual outcome of an episode of pneumonia depends on how ill the person is when he or she is first diagnosed.

In the United States, about one out of every twenty people with pneumococcal pneumonia will die.[2] In cases where pneumonia progresses to blood poisoning (bacteremia), one of every five will die. The death rate (or mortality) also depends on the underlying cause of the pneumonia. Pneumonia caused by Mycoplasma, for instance, is associated with little mortality. However, about half of the people who develop methicillin-resistant Staphylococcus aureus (MRSA) pneumonia while on a ventilator will die.[3] In regions of the world without advanced health care systems, pneumonia is even deadlier. Limited access to clinics and hospitals, x-rays, antibiotic choices, and inability to treat underlying conditions will inevitably lead to higher rates of death from pneumonia.

  • Individuals who are treated for CAP outside of the hospital have a mortality rate of less than 1%.
  • Fever typically responds in the first two days of therapy and other symptoms resolve in the first week.
  • The CXR, however, may remain abnormal for at least a month, even when CAP has been successfully treated.
  • Amongst individuals who require hospitalization, the mortality rate averages 12% overall, but it is as much as 40% in people who have bloodstream infections or require intensive care.[3]
  • When CAP does not respond as expected, there are several possible causes.
  • A complication of CAP may have occurred or a previously unknown health problem may be playing a role.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 "CDC Pneumococcal Disease Clinical Features".
  2. ↑ http://www.kidshealth.org/parent/infections/bacterial_viral/pneumonia.html
  3. ↑ Combes A, Luyt CE, Fagon JY, Wollf M, Trouillet JL, Gibert C, Chastre J; PNEUMA Trial Group. Impact of methicillin resistance on outcome of Staphylococcus aureus ventilator-associated pneumonia. Am J Respir Crit Care Med. 2004 Oct 1;170(7):786-92. PMID 15242840

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