Hospital-acquired pneumonia
Encyclopedia
Hospital-acquired pneumonia (HAP) or nosocomial pneumonia refers to any pneumonia
contracted by a patient in a hospital at least 48–72 hours after being admitted. It is usually caused by a bacterial infection
, rather than a virus
.
HAP is the second most common nosocomial infection
(urinary tract infection
is the most common) and accounts for 15–20% of the total. It is the most common cause of death among nosocomial infections and is the primary cause of death in intensive care unit
s.
HAP typically lengthens a hospital stay by 1–2 weeks.
(ventilator-associated pneumonia
), old age, decreased filtration of inspired air, intrinsic respiratory, neurologic, or other disease states that result in respiratory tract obstruction, trauma, (abdominal) surgery, medications, diminished lung volumes
, or decreased clearance of secretions may diminish the defenses of the lung. Also, poor hand-washing and inadequate disinfection of respiratory devices cause cross-infection and are important factors.
, into the lower respiratory tract. Also, "macroaspirations" of esophageal or gastric material is known to result in HAP. Since it results from aspiration either type is called aspiration pneumonia
.
Although gram-negative bacilli are a common cause they are rarely found in the respiratory tract of people without pneumonia, which has led to speculation of the mouth and throat as origin of the infection.
In hospitalised patients who develop respiratory symptoms and fever one should consider the diagnosis. The likelihood increases when upon investigation symptoms are found of respiratory insufficiency, purulent secretions, newly developed infiltrate on the chest X-Ray
, and increasing leucocyte count. If pneumonia is suspected material from sputum or tracheal aspirates are sent to the microbiology department for cultures. In case of pleural effusion
thoracentesis
is performed for examination of pleural fluid. In suspected ventilator-associated pneumonia it has been suggested that bronchoscopy
(BAL
) is necessary because of the known risks surrounding clinical diagnoses.
, one might consider oseltamivir
. In case of legionellosis
, erythromycin
or fluoroquinolone.
A third generation cephalosporin
(ceftazidime
) + carbapenems (imipenem
) + beta lactam & beta lactamase inhibitors (piperacillin
/tazobactam
)
A study showed that gastric feed supplementation with ginger
extract might help reduce the incidence nosocomial pneumonia.
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
contracted by a patient in a hospital at least 48–72 hours after being admitted. It is usually caused by a bacterial infection
Bacterial pneumonia
Bacterial pneumonia is a type of pneumonia caused by bacterial infection.-Sign and symptoms:*Fever*Rigors*Cough*Dyspnea*Chest pain*Pneumococcal pneumonia can cause Hemoptysis-Gram positive:...
, rather than a virus
Viral pneumonia
Viral pneumonia is a pneumonia caused by a virus.Viruses are one of the two major causes of pneumonia, the other being bacteria; less common causes are fungi and parasites...
.
HAP is the second most common nosocomial infection
Nosocomial infection
A nosocomial infection , also known as a hospital-acquired infection or HAI, is an infection whose development is favoured by a hospital environment, such as one acquired by a patient during a hospital visit or one developing among hospital staff...
(urinary tract infection
Urinary tract infection
A urinary tract infection is a bacterial infection that affects any part of the urinary tract. Symptoms include frequent feeling and/or need to urinate, pain during urination, and cloudy urine. The main causal agent is Escherichia coli...
is the most common) and accounts for 15–20% of the total. It is the most common cause of death among nosocomial infections and is the primary cause of death in intensive care unit
Intensive Care Unit
thumb|220px|ICU roomAn intensive-care unit , critical-care unit , intensive-therapy unit/intensive-treatment unit is a specialized department in a hospital that provides intensive-care medicine...
s.
HAP typically lengthens a hospital stay by 1–2 weeks.
Signs and symptoms
New or progressive infiltrate on the chest X-Ray with one of the following:- FeverFeverFever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
> 37.8 °C (100 °F) - Purulent sputum
- Leucocytosis > 10.000 cells/μl
Types
- Bacterial pneumoniaBacterial pneumoniaBacterial pneumonia is a type of pneumonia caused by bacterial infection.-Sign and symptoms:*Fever*Rigors*Cough*Dyspnea*Chest pain*Pneumococcal pneumonia can cause Hemoptysis-Gram positive:...
: The majority of cases related to various gram-negativeGram-negativeGram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...
bacilli (52%) and S. aureusStaphylococcus aureusStaphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
(19%), usually of the MRSAMethicillin-resistant Staphylococcus aureusMethicillin-resistant Staphylococcus aureus is a bacterium responsible for several difficult-to-treat infections in humans. It is also called multidrug-resistant Staphylococcus aureus and oxacillin-resistant Staphylococcus aureus...
type. Others are HaemophilusHaemophilusNot to be confused with Haemophilia.Haemophilus is a genus of Gram-negative, pleomorphic, coccobacilli bacteria belonging to the Pasteurellaceae family. While Haemophilus bacteria are typically small coccobacilli, they are categorized as pleomorphic bacteria because of the wide range of shapes they...
spp. (5%). In the ICU results were S. aureus(17.4%), P. aeruginosa (17.4%), Klebsiella pneumoniaeKlebsiella pneumoniaeKlebsiella pneumoniae is a Gram-negative, non-motile, encapsulated, lactose fermenting, facultative anaerobic, rod shaped bacterium found in the normal flora of the mouth, skin, and intestines....
and EnterobacterEnterobacterEnterobacter is a genus of common Gram-negative, facultatively-anaerobic, rod-shaped bacteria of the family Enterobacteriaceae. Several strains of the these bacteria are pathogenic and cause opportunistic infections in immunocompromised hosts and in those who are on mechanical ventilation...
spp. (18.1%), and Haemophilus influenzaeHaemophilus influenzaeHaemophilus influenzae, formerly called Pfeiffer's bacillus or Bacillus influenzae, Gram-negative, rod-shaped bacterium first described in 1892 by Richard Pfeiffer during an influenza pandemic. A member of the Pasteurellaceae family, it is generally aerobic, but can grow as a facultative anaerobe. H...
(4.9%).
- Viral pneumoniaViral pneumoniaViral pneumonia is a pneumonia caused by a virus.Viruses are one of the two major causes of pneumonia, the other being bacteria; less common causes are fungi and parasites...
: influenzaInfluenzaInfluenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae , that affects birds and mammals...
and respiratory syncytial virus and, in the immunocompromised host, cytomegalovirusCytomegalovirusCytomegalovirus is a viral genus of the viral group known as Herpesviridae or herpesviruses. It is typically abbreviated as CMV: The species that infects humans is commonly known as human CMV or human herpesvirus-5 , and is the most studied of all cytomegaloviruses...
- cause 10-20% of infections.
Ventilator-associated pneumonia
Ventilator-associated pneumonia (VAP) is a sub-type of hospital-acquired pneumonia (HAP) which occurs in people who are receiving mechanical ventilation. VAP is not characterized by the causative agents; rather, as its name implies, definition of VAP is restricted to patients undergoing mechanical ventilation while in a hospital. A positive culture after intubation is indicative of ventilator-associated pneumonia and is diagnosed as such. In order to appropriately categorize the causative agent or mechanism it is usually recommended to obtain a culture prior to initiating mechanical ventilation as a reference.Risk factors
Among the factors contributing to contracting HAP are mechanical ventilationMechanical ventilation
In medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. This may involve a machine called a ventilator or the breathing may be assisted by a physician, respiratory therapist or other suitable person compressing a bag or set of bellows...
(ventilator-associated pneumonia
Ventilator-associated pneumonia
Ventilator-associated pneumonia is a sub-type of hospital-acquired pneumonia which occurs in people who are receiving mechanical ventilation. VAP is not characterized by the causative agents; rather, as its name implies, definition of VAP is restricted to patients undergoing mechanical...
), old age, decreased filtration of inspired air, intrinsic respiratory, neurologic, or other disease states that result in respiratory tract obstruction, trauma, (abdominal) surgery, medications, diminished lung volumes
Lung volumes
Lung volumes and lung capacities refer to the volume of air associated with different phases of the respiratory cycle. Lung volumes are directly measured...
, or decreased clearance of secretions may diminish the defenses of the lung. Also, poor hand-washing and inadequate disinfection of respiratory devices cause cross-infection and are important factors.
Pathogenesis
Most nosocomial respiratory infections are caused by so-called skorvatch microaspiration of upper airway secretions, through inapparent aspirationPulmonary aspiration
Pulmonary aspiration is the entry of material from the oropharynx or gastrointestinal tract into the larynx and lower respiratory tract...
, into the lower respiratory tract. Also, "macroaspirations" of esophageal or gastric material is known to result in HAP. Since it results from aspiration either type is called aspiration pneumonia
Aspiration pneumonia
Aspiration pneumonia is bronchopneumonia that develops due to the entrance of foreign materials into the bronchial tree, usually oral or gastric contents...
.
Although gram-negative bacilli are a common cause they are rarely found in the respiratory tract of people without pneumonia, which has led to speculation of the mouth and throat as origin of the infection.
Diagnosis
Chest X-ray
In medicine, a chest radiograph, commonly called a chest X-ray , is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures...
, and increasing leucocyte count. If pneumonia is suspected material from sputum or tracheal aspirates are sent to the microbiology department for cultures. In case of pleural effusion
Pleural effusion
Pleural effusion is excess fluid that accumulates between the two pleural layers, the fluid-filled space that surrounds the lungs. Excessive amounts of such fluid can impair breathing by limiting the expansion of the lungs during ventilation.-Pathophysiology:...
thoracentesis
Thoracentesis
Thoracentesis , also known as thoracocentesis or pleural tap, is an invasive procedure to remove fluid or air from the pleural space for diagnostic or therapeutic purposes. A cannula, or hollow needle, is carefully introduced into the thorax, generally after administration of local anesthesia...
is performed for examination of pleural fluid. In suspected ventilator-associated pneumonia it has been suggested that bronchoscopy
Bronchoscopy
Bronchoscopy is a technique of visualizing the inside of the airways for diagnostic and therapeutic purposes. An instrument is inserted into the airways, usually through the nose or mouth, or occasionally through a tracheostomy. This allows the practitioner to examine the patient's airways for...
(BAL
Bronchoalveolar lavage
Bronchoalveolar lavage is a medical procedure in which a bronchoscope is passed through the mouth or nose into the lungs and fluid is squirted into a small part of the lung and then recollected for examination. BAL is typically performed to diagnose lung disease...
) is necessary because of the known risks surrounding clinical diagnoses.
Differential diagnosis
- AtelectasisAtelectasisAtelectasis is defined as the collapse or closure of alveoli resulting in reduced or absent gas exchange. It may affect part or all of one lung. It is a condition where the alveoli are deflated, as distinct from pulmonary consolidation.It is a very common finding in chest x-rays and other...
- Congestive heart failureCongestive heart failureHeart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...
- Pulmonary embolismPulmonary embolismPulmonary embolism is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream . Usually this is due to embolism of a thrombus from the deep veins in the legs, a process termed venous thromboembolism...
Treatment
Usually initial therapy is empirical. If sufficient reason to suspect influenzaInfluenza
Influenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae , that affects birds and mammals...
, one might consider oseltamivir
Oseltamivir
Oseltamivir INN , an antiviral drug, slows the spread of influenza virus between cells in the body by stopping the virus from chemically cutting ties with its host cell; median time to symptom alleviation is reduced by 0.5–1 day. The drug is sold under the trade name Tamiflu, and is taken orally...
. In case of legionellosis
Legionellosis
Legionellosis is a potentially fatal infectious disease caused by gram negative, aerobic bacteria belonging to the genus Legionella. Over 90% of legionellosis cases are caused by Legionella pneumophila, a ubiquitous aquatic organism that thrives in temperatures between , with an optimum temperature...
, erythromycin
Erythromycin
Erythromycin is a macrolide antibiotic that has an antimicrobial spectrum similar to or slightly wider than that of penicillin, and is often used for people who have an allergy to penicillins. For respiratory tract infections, it has better coverage of atypical organisms, including mycoplasma and...
or fluoroquinolone.
A third generation cephalosporin
Cephalosporin
The cephalosporins are a class of β-lactam antibiotics originally derived from Acremonium, which was previously known as "Cephalosporium".Together with cephamycins they constitute a subgroup of β-lactam antibiotics called cephems.-Medical use:...
(ceftazidime
Ceftazidime
Ceftazidime is a third-generation cephalosporin antibiotic. Like other third-generation cephalosporins, it has broad spectrum activity against Gram-positive and Gram-negative bacteria. Unlike most third-generation agents, it is active against Pseudomonas aeruginosa, however it has weaker activity...
) + carbapenems (imipenem
Imipenem
Imipenem is an intravenous β-lactam antibiotic developed in 1980. It has an extremely broad spectrum of activity.Imipenem belongs to the subgroup of carbapenems. It is derived from a compound called thienamycin, which is produced by the bacterium Streptomyces cattleya...
) + beta lactam & beta lactamase inhibitors (piperacillin
Piperacillin
Piperacillin is an extended spectrum beta-lactam antibiotic of the ureidopenicillin class.It is normally used together with a beta-lactamase inhibitor such as tazobactam. The combination drug piperacillin/tazobactam is commercially available as e.g. Tazocin, Zosyn, Brodactam, Piptaz and as Trezora...
/tazobactam
Tazobactam
Tazobactam is a compound that inhibits the action of bacterial beta-lactamases. It is added to the extended spectrum beta-lactam antibiotic piperacillin to produce Tazocin or Zosyn or Piprataz...
)
A study showed that gastric feed supplementation with ginger
Ginger
Ginger is the rhizome of the plant Zingiber officinale, consumed as a delicacy, medicine, or spice. It lends its name to its genus and family . Other notable members of this plant family are turmeric, cardamom, and galangal....
extract might help reduce the incidence nosocomial pneumonia.
External links
- Hospital-Acquired, Health Care Associated, and Ventilator-Associated Pneumonia from the Cleveland Clinic
- Cecil Textbook of Medicine