Lower Respiratory Tract Infections: AECOPD, Aspiration, and Pneumonia in the COVID-19 Era (Chapter 1)

24 November, 2022

My name is Hans Liu. I’m an Infectious Disease Physician from the United States. I’ll be speaking about lower respiratory tract infections, specifically Acute Exacerbations of COPD (AECOPD), as well as aspiration and pneumonia, as they are now affected by the COVID-19 era.

As an overview, we’ll start with the definition of Chronic Obstructive Pulmonary Disease (COPD) and some of the ways that COVID-19 has interacted with it. We’ll talk about measuring COPD and why the exacerbations occur. We’ll look at approaching the management of COPD at multiple levels. And then, finally focus on the use of antibiotics for exacerbations of COPD. We’ll then discuss the role of fluoroquinolone antibiotics and their pros and cons when treating an exacerbation of COPD. We’ll divert a little bit to aspiration and its role in pneumonia, and what that means for microbial pathogens and also antibiotic selection. And finally focus on Lower Respiratory Tract (gram-negative) Infections (LRTIs), including AECOPD, and discuss the antibiotic selection for treating this.

Now, the reason LRTI treatment is undergoing reassessment, as far as COVID-19 is prevalent and affecting people and patients worldwide. There has also been an ongoing shift in the types of respiratory tract pathogens causing LRTIs and their antibiotic susceptibility profiles. So, it’s become very timely for us to look again at what is probably the best way to approach managing AECOPD in the COVID-19 era.

Now, COPD is the third leading cause of death worldwide. In the last year, we have records of 2019 – there were over 3 million deaths. In the United States, we find that anywhere from 4.5–9% of adults in any given state suffer from COPD. In the Asia Pacific region, the average prevalence has been estimated at around 6%; however, this will be higher in locations with higher smoking rates and or occupational exposures, for example, the toxic dusts. Of these people with COPD around the world, approximately half of them will have one or more exacerbations during the course of a year. And in fact, one out of five will become sick enough to be admitted to the hospital with an exacerbation of COPD. The numbers are even more striking for COVID-19 – from the beginning of the epidemic at the end of 2019 to August of 2022, approximately 610 million cases of COPD were reported worldwide. Of these, there were 6.5 million deaths, meaning that about one out of each 100 people who develop COVID 19 died. Risk factors for COVID-19 include asthma, and chronic lung disease, which we’ll talk about. And in addition, patients who are older, above the age of 65 are residents of chronic care facilities are prone to developing COVID-19. And one interesting thing to consider, as we go about our daily practices is that AECOPDs, as well as early or mild COVID-19 can be fairly hard to distinguish in the first day or two.

Now, we have some definitions. COPD is a common and preventable early as well as treatable late disease with airflow limitation. Unfortunately, it is usually progressive and there is an associated chronic inflammatory response to the lungs, which worsens lung function. And as we’ve already mentioned, somewhere around 5–6% of people in the world suffer from COPD, exacerbations and comorbidities contribute to the overall severity in these people. We also have variants like chronic bronchitis, which is a chronic cough for three months in each of two successive years, which has no other explanation. Other patients present with a variant called emphysema, which is abnormal and permanent enlargement of air spaces with destruction of aerospace walls – this is evident on examination where you don’t hear very much in the way of breath sounds, or on radiographic imaging where there’s relatively little tissue and a lot of airspace. And finally, asthma is a chronic inflammatory disorder with airflow obstruction, which however, is reversible as opposed to some other forms of COPD.

Now, in the past the European respiratory society approach the diagnosis of COPD via number of levels. The first was the clinical presentation, and you’ll see that a large population is at risk, either from habits like smoking, or occupation or genetics. The ones who do develop COPD will become symptomatic with cough, shortness of breath. Some of them unfortunately go on to develop significant exacerbations, which are limiting to the quality of life. And unfortunately, in the worst case, multiple exacerbations can lead to hospitalization due to respiratory failure, and ultimately death. The interventions that can be applied along the way before development of COPD – smoking cessation is very important. Once patients have developed symptoms, disease management with various ways of avoiding exacerbations and infections or using bronchodilators using steroids become a way to diminish the impact of COPD on a patient’s lifestyle. Once patients become limited by COPD and its exacerbations, pulmonary rehabilitation becomes critical to help them cope with it and again, delay the worsening of function. And finally, in more recent years, we’ve seen some new options both diagnostically and therapeutically, for example interventional, along reduction surgery and extreme cases. Now, one thing that’s good to keep in mind is that disease progression – studies have shown that the forced expiratory volume in one second is inversely proportional to the severity of the disease i.e., as FEV1 declines, the disease become more severe, and the patient has more symptoms and greater chance of a physician encounter or hospitalization.