Good afternoon, I am Dr Panpit Suwangool, an Infectious Disease specialist, working at Bangkok Medical Center in Bangkok, Thailand. I am in charge of Infection Control Committee, and I am also on the advisory board of the Infectious Disease Association of Thailand. Today, I am going to talk about lower respiratory tract infection, in particular pneumonia.

So, my scope will include: what is pneumonia and how to diagnose pneumonia; secondly, the etiology of community-acquired pneumonia (CAP); thirdly, appropriate treatment of CAP; fourthly, the role of fluoroquinolone in the treatment of pneumonia. I will end with the take-home message.

How to diagnose and how to classify pneumonia? You can see in the diagram, the upper and lower airway – once the causative agent, any microorganism, gets down to the lower part of the respiratory tree, it could be in the large airway, medium airway, or alveolar space. When the microorganism is in the alveolar space and causes severe pathology, we call it pneumonia.

Classification of pneumonia: For practical management, we have to combine all classifications. Firstly, by location – if the infection is acquired or occurs in the community, we call it CAP because in this kind of pneumonia, usually, the causative agent is not resistant; and hospital-acquired pneumonia, which means that infection occurs or is acquired following more than 48 hours of stay in the hospital; we divide this particular group into hospital-acquired pneumonia and ventilator-associated pneumonia, which happens to a patient who is on mechanical ventilation and is a kind of infection that is more severe than hospital-acquired pneumonia. And secondly, the classification will be based on the immune status of the patient – if the patient has no immune dysfunction, we call it CAP in an immunocompetent patient, and if the patient has immune dysfunction, we call it pneumonia in an immunocompromised host because the management, particularly at the early stage, is different. And thirdly, by microbiology: different causative microorganisms could be virus, bacteria, mycobacteria, parasite, or even fungus. So, this classification relies upon definitive microbiology; sometimes it is very difficult to get the specimen, to get the sputum or respiratory secretion.

So how to diagnose pneumonia clinically? Diagnosis of pneumonia depends on symptoms and signs of respiratory tract infection. But the gold standard has to be imaging or radiological changes, for example, the pulmonary infiltrate. And also, we need to identify what is the causative pathogen. Sometimes, even with steps one–two–three, we cannot differentiate whether it is an infectious disease or not. We have to go by the clinical response. For example, if a patient comes in for X-ray imaging, but we cannot identify the causative agent or some inflammatory markers are not abnormal, we go by the treatment response. For example, we give an empiric antimicrobial, and if the patient responds, we classify this as pneumonia.

So, for imaging and clinical symptoms that are commonly used: increased cough; increased sputum production; shortness of breath, particularly on mild exertion; pleuritic chest pain; sometimes fever, particularly in the elderly, but sometimes there is no fever; abnormal lung size; crackle or rales; and also, some laboratory markers of infection, for example, leukocytosis. These clinical symptoms that present as an acute disease, beginning with fever with chills and also pleuritic chest pain and progressing in a few hours, indicate severe pneumonia. Pneumonia is one of the leading causes of morbidity and mortality worldwide, particularly in developing countries.

How common is and how often do we see CAP? Incidence of CAP varies from country to country, and from season to season. As you can see here, in the United States, the incidence varies from five to 11 cases per 1000. In European countries, it even varies from 68 to 7000 per 100,000. In Thailand, in the year 2019, the incidence was around 388 per 100,000 population; however, in the all over incidence of pneumonia, the common factor is the age of the patient. In the elderly, the incidence is higher than in the younger people. As you can see here, in 75- to 84-year-olds, the incidence is 68 to 88 per 10,000 adults, but after 85 years, the incidence is even higher, at 160 to 224 per 10,000 adults. So that’s why for pneumonia in the elderly, we have to give appropriate treatment as soon as possible.