Clinical Characteristics of Lung Abscess

Next, the next topic to be treated is one of the complications of ill-treated and unresolved respiratory processes, such as the formation of Lungs Abscesses, which corresponds to those limited collections containing pus, odorless or foul-smelling, developed in full pulmonary parenchyma.

Lung abscess is described as a suppurative process. Well defined radiologically, usually product of poly microbial organisms, it progresses over time to central necrosis and may compromise one or more areas of the pulmonary parenchyma.

^{Anatomy lungs breathing human health respiratory. Public domain image. Source Pixabay}

Causal Agents

As described above, most abscesses are of Polymicrobial Etiology, with 95% of cases by anaerobic microorganisms. Gram-positive cocci such as Staphylococcus aureus and Streptococcus pneumonia may also be involved.

In immunodeficient patients, the agent Mycobacterium tuberculosis, capable of causing bronchiectasis, infected cysts and even pulmonary infarctions, has been isolated very frequently. In its evolution, it forms a cavity that later fills with infectious liquid known as "abscess". As for the anaerobic microorganisms (Clostridim perfringens, septicum and peptostreptococcus), however, there are frequent mixed infections in which microorganisms of the oropharyngeal flora participate. Finally, the most frequently found aerobic germs are staphylococcus, hemolytic and non-hemolytic streptococcus and E.coli.

^{Micrograph obtained from TEM of Mycobacterium tuberculosis. Public domain image. Source Wikipedia. Author: Elizabeth "Libby" White (PHIL # 8433). CC BY-SA 3.0}

Physiopathology

The microorganisms have the capacity to reach the lung by four possible routes, or also called entry doors and these are: post-pneumonic (subsequent to respiratory process type pneumonia), by hematogenous dissemination, by direct extension or by contamination. The bacterium most frequently responsible for lung abscesses is staphylococcus, which presents as pneumonia accompanied almost always by pleural effusion.

Two mechanisms are recognized in the pathogenesis of lung abscess:

Aspiration-macroaspiration of oropharyngeal and/or gastric content, called bronchoaspiration are those patients in special situations (epileptics in crisis, neurological deterioration, etc.) and microaspiration in patients with periodontal affection, secondary to an infectious dental process called dental caries that are absceded. This mechanism has the capacity to form an area of pneumonitis (which is located by gravity, in the apical segment of the lower lobes or in the posterior segments of the upper lobes), the lesion is extended by bronchial infectious emboli and proliferates.

Dissemination by hematogenous route, although it is the least common, but cases have been reported, especially by lung staphylococcias. There are factors that predispose or favor the formation of lung abscesses, and are those circumstances that increase the risk of aspirations of fluids themselves. Examples: acute alcohol intoxication, head trauma with loss of consciousness, convulsive crises, abundant septic focuses and instrumentation in the upper airway, periodontal abscess, lung tuberculosis, among others.

The hematogenous dissemination as a result of septic processes, originating septic thrombus, coming from infected peripheral veins; usually the most frequent germs are the coagulase-positive and coagulase-negative coagulase-staphylococcus and enteropathogens.

By direct secondary extension to infectious processes such as hepatic abscesses that can be bacterial, amoebic or mixed. The oropharyngeal aspirational etiology is more common in adults, where the aspirated material, by gravity reaches the lung, and the affected lobe depends on the position and time of aspiration. In the supine position, the posterior segment of the upper lobes and the apical segments of the lower lobes are the most severely affected.

Classification

Lung abscesses can be classified into primary and secondary.

Primary abscesses occur in a lung parenchyma in a previously healthy human being.

The secondary ones occur in patients with underlying pulmonary processes with pre-existing cavities or not, which favor them, call pulmonary tuberculosis, immunosuppressive processes, HIV, etc.

Clinical Manifestations

Initial manifestations depend on the patient's immune status and the causative agent, which may be expressed by fever, productive cough, generalized weakness, and anorexia.

This symptomatology progresses and is associated with a state of bedriddenness with very high fever and pleuritic pain that is more intense on the side of the lung lesion, as well as weight loss and anemia. Finally, the patient refers cough with hemoptoic expectoration, vomica type and halitosis.

Diagnosis

Laboratory

Blood cultures: May be positive in patients with Staphylococcus Aureus infection and gram-negative bacilli, which are suspected by hematogenous dissemination.

Sputum culture, with gram, Bk and KOH coloration, both for aerobic and anaerobic germs and gram positive and negative.

Pleural Liquid Culture may be requested in those patients with Lungs Abscesses associated to Pleural Effusion, which by means of diagnostic and/or therapeutic thoracentesis can isolate the causal agent.

Imaging studies

The diagnosis is confirmed by X-ray and chest CT scan (Rx Tx, TC Tx).

Where the pathognomonic sign of this entity in the chest X-ray is the presence of a cavity with hydroaeréo level.

Fibrobronchoscopy (FBC) with bronchoalveolar lavage (LBA) is indicated in cases of torpid evolution or suspicion of an underlying neoplasm. There are currently no guidelines to support its routine use in diagnosis.

Treatment/Conclusions

The medical treatment has its strong base in antibiotic therapy, preferably combined where the most frequent is the use of Clindamycin is the most recommended antibiotic associated with a broad-spectrum antibiotic, where the common is the use of Cefalospirin 3rd generation, or in certain opportunities is accepted the use of an Aminopenicillin with an inhibitor of betalactamase, thinking of gram positive agents.

Metronidazole is usually another good alternative associated with third generation Cephalosporins such as Cefotaxime and Ceftriaxone. There is controversy about the duration of treatment some literature recommend a minimum of three weeks and others are based on prolonged treatment of 4 to 8 weeks, depending on the patient's clinical response, radiological evolution and resolution.

The indication for surgical drainage is due to the failure of medical treatment, which may be associated with neoplastic process more frequently.

Sources of support in the publication

Lung Abscess: Diagnosis, Treatment and Mortality. International Journal of Pharmaceutical Science Invention ISSN (Online): 2319 – 6718, ISSN (Print): 2319 – 670X. Murtaza Mustafa, HM.Iftikhar, RK, Muniandy, SA.Hamid, MM.Sien, N.ootha.

How Important Are Anaerobic Bacteria in Aspiration Pneumonia When Should They Be Treated and What Is Optimal Therapy

Aspiration, Empyema, Lung Abscesses, and Anaerobic Infections

Gram-Positive Anaerobic Cocci. Clin Microbiol Rev. 1998 Jan; 11(1): 81–120. D. A. Murdoch

Cavitary Pulmonary Disease. Clin Microbiol Rev. 2008 Apr; 21(2): 305–333. L. Beth Gadkowski and Jason E. Stout

Lung Abscess. A.J. Chandrasekhar/Vijay Yeldandi

What Is a Lung Abscess?

Lung abscess-etiology, diagnostic and treatment options. Ann Transl Med. 2015 Aug; 3(13): 183. Ivan Kuhajda, Konstantinos Zarogoulidis, Katerina Tsirgogianni, Drosos Tsavlis, Ioannis Kioumis, Christoforos Kosmidis, Kosmas Tsakiridis, Andrew Mpakas, Paul Zarogoulidis,corresponding author Athanasios Zissimopoulos, Dimitris Baloukas, and Danijela Kuhajda

Infection

Septic Thrombophlebitis

Lung abscess Wikipedia

Lung Abscess

Abscess

steemSTEM is a project of the chain of blocks that supports the scientific content in different areas of science. If you want to know more about this wonderful project you can join the server in discord

This article will be published at https://www.steemstem.io/

I hope you enjoyed my content.