The Infectious Diseases Society of America (IDSA) Foundation recently hosted a webinar on the continuous challenges of non-COVID respiratory tract infections as part of their Dr. John G. Bartlett Memorial Education Series. The World Health Organization (WHO) reports respiratory tract infections as the leading cause of disease burden and lower respiratory tract infection (LRTI) as the third leading cause of death worldwide .
The webinar, available on-demand here, focuses on lower respiratory tract infections and is divided into three presentations. In the first talk of the webinar, Dr. Donna Wolk discusses screening and diagnosis of lower respiratory tract infections and surveillance options. In the second presentation Dr. Leila Hojat discusses the pathogenesis, etiology and clinical manifestation of pneumonia. The third topic covers antibiotic decision-making and the importance of vaccines, presented by Dr. Maryrose Laguio-Vila.
In the second presentation of the webinar, Dr. Hojat walks the audience through the pathogenesis, etiology, and clinical manifestation of pneumonia. For pneumonia, the pathogen usually enters through inhalation of aerosolized material. The other pathogen entrances include aspiration of upper airway microorganisms and metastatic seeding from blood. To establish an infection, the pathogen needs to overcome the host defense mechanisms. Dr. Hojat points out that the upper respiratory tract filters out larger particles, and the terminal airways possess a set of weapons such as alveolar lining fluid, pattern recognition receptors, and inflammatory mediators to mount more sophisticated response towards infiltrating pathogens. Dr. Hojat highlights several reasons why the host defense system may be compromised, and lists virulence factors that pathogens utilize to overcome host defense mechanism.
The etiology of acute pneumonia can depend on the setting, such as community-acquired pneumonia (CAP) or hospital acquired and ventilator associated pneumonia (HAP/VAP). Streptococcus pneumonia is the most common “typical organism” for CAP, whereas “atypical organism” includes viruses and bacteria that are difficult to detect. HAP/VAP includes pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa. Dr. Hojat further highlights that the etiology of pneumonia can also vary based on various risk factors such as the duration of the infection. She further discusses major causative agents for subacute and chronic pneumonia.
Clinical manifestation of pneumonia can vary significantly between patient and causative agent. Dr. Hojat highlights that pneumonia is a clinical diagnosis, based on presenting symptoms and signs detected during physical exam. However, utilizing imagining techniques, such as chest x-rays, and/or in vitro diagnostic tests (such as culture or molecular diagnostics) can provide confirmational results to support the diagnosis and direct proper treatment.
The webinar is available on-demand here to learn more about pathogenesis, etiology, and clinical manifestation of respiratory tract as well as diagnosis and antibiotic stewardship.
About the Speaker
Leila Hojat, MD is an infectious diseases physician at University Hospitals Cleveland Medical Center and assistant professor of medicine at Case Western Reserve University. Dr. Hojat currently serves as the director of antimicrobial stewardship at University Hospitals where she has been central to the system’s pandemic response and has greatly expanded the stewardship program. She has a special interest in respiratory infections and is currently serving on the advisory board for the 2023 ATS/IDSA community-acquired pneumonia guidelines.
 Avendaño Carvajal L, Perret Pérez C. Epidemiology of Respiratory Infections. Pediatric Respiratory Diseases. 2020 Feb 1:263–72. doi: 10.1007/978-3-030-26961-6_28. PMCID: PMC7120591.