What Is Lung Abscess? Causes, Symptoms, Treatment

Pulmonary abscess? or lung abscess is a lung infection? which destroys the lung parenchyma leading to cavitations and central necrosis in localized? areas formed by thick-walled purulent material. It can be primary or secondary. Lung abscesses can occur at any age, but it seems that pediatric pulmonary abscess morbidity is lower than in adults.

Types of Lung Abscess?

Causes of Lung Abscess?

Lung abscess? can be bacterial? including

• Aerobic – Streptococcus spp., Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, or very rarely Mycoplasma pneumonia,
• Anaerobic – such as Bacteroides spp., Fusobacterium spp., and Peptostreptococcus spp. or
• Fungal? – in immunocompromised patients [rx].

A primary abscess? is one which develops as a result of primary infection? of the lung. They most commonly arise from aspiration, necrotizing pneumonia or chronic? pneumonia, e.g. pulmonary tuberculosis immunodeficiency. In patients who develop abscesses as a result of aspiration, mixed infections are most common, including anaerobes. Some organisms are particularly prone to causing significant necrotizing pneumonia resulting in cavitation and abscess? formation. These include

• Staphylococcus aureus
• Klebsiella sp: Klebsiella pneumonia
• Pseudomonas sp
• Proteus sp

In immunocompromised patients, additional organisms may also be implicated including 

• Candida albicans: pulmonary candidiasis
• Legionella micdadei and Legionella pneumophila: Legionella pneumonia
• Pneumocystis carinii (uncommon): Pneumocystis jirovecii pneumonia

A secondary abscess? is one which develops as a result of another condition. Examples include:

• Bronchial obstruction – bronchogenic carcinoma, inhaled foreign body
• Hematogenous spread – bacterial? endocarditis, IV drug use
• Direct extension from adjacent infection? – mediastinum, subphrenic, chest wall
• Aspiration of oropharyngeal or gastric secretion
• Septic emboli
• Necrotizing pneumonia
• Vasculitis: Granulomatosis with polyangiitis
• Necrotizing tumors: 8% to 18% are due to neoplasms across all age groups, higher in older people; primary squamous carcinoma of the lung is the most common.

Organisms

In the post-bacterial? infections. সহজ বাংলা: ব্যাকটেরিয়ার সংক্রমণের ওষুধ।" data-rx-term="antibiotic" data-rx-definition="An antibiotic is a medicine used to treat bacterial infections. সহজ বাংলা: ব্যাকটেরিয়ার সংক্রমণের ওষুধ।">antibiotic? era pattern of frequency is changing. In older studies, anaerobes were found in up to 90% cases but they are much less frequent now.^[rx]

• Anaerobic bacteria – Actinomyces, Peptostreptococcus, Bacteroides, Fusobacterium species,
• Microaerophilic streptococcus  – Streptococcus milleri
• Aerobic bacteria – Staphylococcus, Klebsiella, Haemophilus, Pseudomonas, Nocardia, Escherichia coli, Streptococcus, Mycobacteria
• Fungi – Candida, Aspergillus
• Parasites – Entamoeba histolytic
• Bronchial obstruction- bronchi are the two branches of the windpipe that lead into the lungs. If they are blocked by tissue swelling?, cancerous tumors, or foreign objects, a lung abscess? may form from infection trapped behind the blockage.
• The spread of infection – About 20% of cases of pneumonia that causes the death of lung tissue (necrotizing pneumonia) will develop into lung abscess. Lung abscess can also be caused by the spread of other infections from the liver, abdominal cavity, or open chest wounds. Rarely, AIDS patients can develop lung abscess from Pneumocystis carinii and other organisms that take advantage of a weakened immune system.

Symptoms of Lung Abscess

• Early signs and symptoms of lung abscess cannot be differentiated from pneumonia and include fever with shivering, cough, night sweats, dyspnea, weight loss and fatigue, chest pain and sometimes anemia.
• At the beginning cough is non-productive, but when communication with bronchus appears, the productive cough (vomique) is the typical sign [rx,rx].
• The onset of symptoms is often gradual, but in necrotizing staphylococcal or gram-negative bacillary pneumonia patients can be acutely ill. Cough, fever with shivering, and night sweats are often present. Cough can be productive of foul-smelling purulent mucus (≈70%) or less frequently with blood in one-third of cases).^[rx] Affected individuals may also complain of chest pain, shortness of breath, lethargy and other features of chronic illness.
• Those with a lung abscess are generally cachectic at presentation. Finger clubbing is present in one-third of patients.^[rx] Dental decay is common, especially in alcoholics and children. On examination of the chest, there will be features of consolidation such as localized dullness on percussion and bronchial breath sounds.
• Cough remains productive, sometimes followed by hemoptysis. In patients with chronic abscess clubbing fingers can appear.
• Pulmonary cystic lesions, such as intrapulmonary located bronchial cysts, sequestration or secondary infected emphysematous bullae can be difficult to differentiate, but localization of a lesion and clinical signs can indicate the appropriate diagnosis. Localized pleural empyema can be distinguished by using CT scan or ultrasound [rx].
• Night sweats
• Sputum (a mixture of saliva and mucus) with pus that’s often sour-tasting, foul-smelling, or streaked with blood
• bad breath
• Fever of 101°F or higher
• Chest pain
• shortness of breath
• Sweating or night sweats
• Weight loss
• Fatigue
• The onset of symptoms is often insidious (more acute if following pneumonia).
• Spiking temperature with rigors and night sweats.
• Cough ± phlegm production (frequently foul-tasting and foul-smelling and often blood-stained).
• Pleuritic chest pain.
• Breathlessness.

Signs

• Tachypnoea.
• Tachycardia.
• Finger clubbing in chronic cases.
• Dehydration.
• High temperature.
• Localized dullness to percussion (if consolidation is also present or effusion).
• Bronchial breathing and/or crepitations (if consolidation is present).
• Also, look for signs of severe periodontal disease and infective endocarditis.

Diagnosis of Lung Abscess

• Laboratory studies – Raised inflammatory markers (high ESR, CRP) are common but nonspecific. Examination of the coughed-up mucus is important in any lung infection and often reveals mixed bacterial flora. Transtracheal or transbronchial (via bronchoscopy) aspirates can also be cultured. Fiber optic bronchoscopy is often performed to exclude obstructive lesion; it also helps in bronchial drainage of pus.
• Blood cultures – are routinely sterile in anaerobic lung infection. Routine sputum cultures are of limited utility in primary lung abscess as they are routinely contaminated with aerobic upper airway flora. A putrid odor to sputum is characteristic of anaerobic infection. Sputum cultures should be obtained when health-care-associated pathogens are suspected or in post-influenza settings when Staphylococcus aureus superinfection is a concern. Blood cultures may be positive in Lemierre’s syndrome for Fusobacterium necrophorum and in endovascular infections for Staphylococcus aureus.
• Tuberculosis – should always be excluded in an atypical case of lung abscess. All patients should be placed in respiratory isolation and sputum for acid-fast smear and culture obtained.
• Blood testing for galactomannan – a component of the Aspergillus cell wall, should be obtained if invasive aspergillosis is a concern. Testing for beta-glucan (Fungitell), a fungal cell wall component with utility in diagnosing aspergillosis and Pneumocystis, may also be obtained if available. Antibody and antigen testing for histoplasmosis and coccidioidomycosis is available and should be sent in suspect cases; antigen testing for cryptococcus is also available. Laboratory lag times prevent these tests from informing initial decision-making in atypical cases but results may be useful in the event of a desultory clinical response.
• Antinuclear cytoplasmic antibodies – should be sent if vasculitis is a consideration. As noted, cavitary rheumatoid disease generally occurs in the setting of clinically-apparent disease. Cavitation of a pulmonary infarct is an unusual initial presentation for thromboembolic disease; D-dimer elevations would be expected in systemic inflammatory disease and would not be useful.

Radiographic features

• As aspiration is the most common cause of pulmonary abscesses, it is no surprise that the superior segment of the right lower lobe is the most common site of infection.
• The classical appearance of a pulmonary abscess is a cavity containing a gas-fluid level. In general, abscesses are round in shape and appear similar in both frontal and lateral projections. Additionally, all margins are equally well seen, although adjacent consolidation may make the assessment of this difficult. These features are helpful in distinguishing a pulmonary abscess from an empyema.

Ultrasound

• Ultrasound does not play a routine role in the assessment of lung abscesses as any aerated intervening lung will prevent visualization. Peripheral abscesses abutting the pleura or with only compressed or consolidated lung may, however, be visible, and should not be mistaken for an empyema ⁴. The consolidated lung may mimic a fluid collection with low-level echoes.

CT Scan

• CT is the most sensitive and specific imaging modality to diagnose a lung abscess. Contrast should be administered, as this enables the identification of the abscess margins, which can otherwise blend with surrounding consolidated lung. Abscesses vary in size and are generally rounded in shape.
• They may contain only fluid or have a gas-fluid level. Typically there is surrounding consolidation, although with treatment the cavity will persist longer than consolidation.  The wall of the abscess is typically thick and the luminal surface irregular. Bronchial vessels and bronchi can be traced as far as the wall of the abscess, whereupon they are truncated.
• Relationship to adjacent bronchi/vessels
  • abscesses will abruptly interrupt the bronchovascular structures
  • empyema will usually distort and compress adjacent lung
• Split pleura sign
  • thickening and separation of visceral and parietal pleura is a sign of empyema
• Wall
  • abscesses have thick irregular walls
  • empyema are usually smoother
• Angle with pleura
  • abscesses usually have an acute angle
  • empyema have obtuse angles

Other Tests You Might Have Include

• Pulse oximetry  – a device is clipped to your finger or ear lobe, and a light on it measures how much oxygen is in your blood.
• Chest X-ray or a computerized tomography (CT) scan – to see if you have pneumonia, blood clot in your lung, or another lung disease. A CT scan puts several X-rays taken from different angles together to make a more complete picture.
• Electrocardiogram (ECG) –  to measure the electrical signals from your heart to see if you’re having a heart attack and find out how fast your heart is beating and if it has a healthy rhythm.
• Patients should be tested for electrolyte abnormalities – endocrine disorders (specifically hyperthyroid) drug-induced causes, infections, drug or chemical withdrawal, and echocardiography to check for structural heart disease. In patients presenting with ischemic stroke and with no prior history of AF, 72-hour Holter monitoring improves the detection rate of silent paroxysmal.[rx]
• Screening spirometry – Can assess how much air you can breathe
• Complete pulmonary function testing – Can evaluate your breathing capabilities in more detail than screening spirometry by measuring how much air you can breathe in and out, as well as how quickly
• Spirometry – A test called spirometry can help show how well your lungs are working. You’ll be asked to breathe into a machine called a spirometer after inhaling a medication called a bronchodilator, which helps widen your airways. The spirometer takes two measurements: the volume of air you can breathe out in one second, and the total amount of air you breathe out. You may be asked to breathe out a few times to get a consistent reading.
• Echocardiography – may be ordered if your EKG suggests that you have heart disease
• Standard exercise treadmill testing – Evaluates your breathing when you have increased oxygen demands
• Complete cardiopulmonary exercise testing – Evaluates your heart and lung function in detail.
• Lung function test – a small, handheld device (a spirometer) that you blow into is used to measure how hard and how quickly you can expel air from your lungs; this can assess how well your lungs are working.

Treatment of Lung Abscess

Empiric antimicrobial therapy

• Clindamycin + second or third-generation cephalosporin
• Ampicillin-sulbactam or amoxicillin-clavulanate
• Moxifloxacin
• Penicillin G + Metronidazole – This should not be given for patients with suspected multi-drug resistant organisms.
• Carbapenems – This is preferred for patients with suspected multi-drug resistant organisms (those with history of prior treatment with broad-spectrum antibiotics, known colonization with resistant organisms, or in whom hospital-acquired infection is suspected).

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• Metronidazole –  as a single therapy, does not appear to be particularly effective, due to polymicrobial flora, presumably, microaerophilic streptococci, such as Streptococcus milleri [rx].
• Antibiotics – for lung abscess are a combination of β-lactam with inhibitors of β-lactamase (ticarcillin-clavulanate, ampicillin-sulbactam, amoxicillin-clavulanate, piperacillin-tazobactam), chloramphenicol, imipenem or meropenem, the second generation of cephalosporins (cefoxitin, cefotetan), the newer generation of fluoroquinolones-moxifloxacin, who shoved to be as effective as combination ampicillin-sulbactam [rx].
• Macrolide – (erythromycin, clarithromycin, azithromycin) have a very good therapeutic effect on poli microbial bacteria in lung abscess, except on fusobacterium species. Vancomycin is very effective for gram-positive anaerobic bacteria.
• Aminoglycosides – are not recommended in the treatment of lung abscess since they poorly pass through the fibrous pyogenic membrane of the chronic abscess. It is recommended to treat lung abscess with broad-spectrum antibiotics, due to polymicrobial flora, such as Clindamycin (600 mg IV on 8 h) and then 300 mg PO on 8 h or combination ampicillin/sulbactam (1.5-3 gr IV on 6 h) [rx].
• Alternative therapy – is piperacillin/tazobactam 3.375 gr IV on 6 h or Meropenem 1 gr IV on 8 h [rx]. For MRSA it is recommended to use linezolid 600 mg IV on 12 h or vancomycin 15 mg/kg BM on 12 h [rx]. Effective answer to antibiotics therapy can be seen after 3-4 days, the general condition will improve after 4-7 days, but complete healing, with radiographic normalization, can be seen after two months.
• Cough medications/Decongestants – may help you to be more comfortable if you are coughing a lot. Guaifenesin is an active ingredient in many cough medications, may be given alone, but is often combined with other drugs, such as codeine, to help your cough. Guaifenesin may also be combined with pseudoephedrine as a decongestant, or anyone of many medications, depending on your symptoms.  Another common medication you may receive is Hydrocodone Bitartrate-Homatropine Methylbromide. This is a narcotic antitussive (anti-cough medication), which will help relieve your cough.
• Antianxiety medications – If you are experiencing anxiety with your emphysema, depending on the cause, your healthcare provider may prescribe an anti-anxiety medication, called an anxiolytic.  These medications will help you to relax. These may include lorazepam or alprazolam. It is important to take these medications only when you are feeling anxious. Do not operate heavy machinery, or drive an automobile while taking these. These medications must be used very cautiously if you have a severe pneumothorax. Discuss the risks and benefits of taking this medication with your doctor or healthcare provider.
• Beclomethasone –  an inhaled steroid, is useful in the treatment of chronic emphysema. Inhaled steroids act directly on the lung tissue, so there are fewer long-term side effects, compared with a pill or IV form. People who have an outbreak of severe shortness of breath and airway inflammation may be ordered a steroid pill, such as prednisone, for a short period of time. This is usually given with inhaled steroids. Patients with severe asthma may require IV administration of another steroid, methylprednisolone.
• Supportive care – Because lung abscess is a serious condition, patients need quiet and bed rest. Hospital care usually includes increasing the patient’s fluid intake to loosen up the secretions in the lungs, and physical therapy to strengthen the patients breathing muscles.
• Chest physiotherapy – for mobilization and drainage of secretions are helpful.