Chest radiography is the most common method to confirm a diagnosis of pneumonia among patients with an appropriate clinical presentation. Radiography and computed tomography demonstrate different imaging patterns in pneumonia, depending on the distribution of lung injury. Lung ultrasound can also identify pneumonia consolidation and interstitial edema. Ultrasound guidance may aid diagnostic thoracentesis.
Lungs are exposed to a contaminated world. The lung-resident immune system is essential for preventing most of the microbes arriving in the lower respiratory tract from developing into infection and pneumonia. When pneumonia does occur, lung-resident immunity determines whether and how complete a recovery can be accomplished. The dynamic interplay between microbes and the immune system within the lung is pivotal host-pathogen interactions for pneumonia pathogenesis.
Air pollution and climate change are intricately linked, each amplifying the other's effects. Both have an impact on respiratory conditions such as asthma, chronic obstructive pulmonary disease, and allergy, most commonly associated with exacerbations of these conditions. They also impact on the occurrence, etiology, and severity, including mortality, of respiratory infections, in particular pneumonia, especially among vulnerable populations. Commonly affected pathogens are many and include bacteria, viruses, and fungi. Ongoing research needs to determine fully the mechanisms and consequences of these environmental changes to understand how best to mitigate against these effects.
Pneumonia remains the leading cause of infectious mortality worldwide, particularly among children less than 5 years of age and older adults. Despite its significant impact on global health, pneumonia is still a neglected disease. Pneumonia advocacy is critical for educating the public about this treatable and preventable condition. It is essential to focus on reducing the current gaps in the effective promotion of pneumonia prevention. The priority measures include promoting pneumonia awareness and education campaigns; increasing investment in pneumonia prevention, diagnosis, and treatment; and conducting further research into the impact and etiology of the disease and the issue of antimicrobial resistance.
Pneumonia is a common and potentially severe condition characterized by infection of the lung parenchyma, involving the alveoli. Pneumonia can be caused by bacteria, viruses, and/or fungi, and it is often diagnosed clinically based on symptoms, evidence of lung dysfunction, and imaging findings. This article outlines the clinically available methods for sampling the respiratory tract, evaluating each technique's advantages, limitations, and optimal applications. We conclude with a discussion of emerging diagnostic methods, focusing on novel noninvasive lower respiratory tract sampling research techniques that show promise for future clinical implementation.
Critically ill, immunocompromised individuals are vulnerable to both common and uncommon etiologies of respiratory infection. Identifying the etiology of infection has therapeutic, prognostic and public health implications. In some circumstances, immunocompromised patients may be empirically treated with excessively broad antibiotics but ultimately be diagnosed with a common cause of pneumonia. In other circumstances, immunocompromised patients may have a non-specific clinical presentation for severe respiratory failure and be diagnosed with a rare etiology of infection. Because this patient population is at risk for a broad array of infections, it is important to understand the advantages and limitations of sampling and diagnostic techniques. Furthermore, the last decades of research have produced novel methods to enhance diagnostic accuracy. Many of these tests are molecular diagnostics that have high sensitivity, but their clinical impact is unknown, particularly in immunocompromised individuals. In this chapter we discuss various approaches to sampling and microbiologic diagnosis in immuncompromised individuals with severe respiratory failure.
Pneumonia is classified into community-acquired pneumonia (CAP) and hospital-acquired pneumonia based on the site of acquisition, and in each, severity and risk factors for multidrug-resistant (MDR) pathogens are evaluated to determine initial treatment. In general, the causative microorganisms for CAP are drug-sensitive, whereas MDR pathogens are more often present in HAP. However, the etiologic pathogens are not strictly dependent on site of acquisition and can be similar among all groups of patients. With advances in medical care provided on an outpatient basis (including in long-term care facilities), CAP caused by MDR pathogens is also on the rise.
Making an etiologic diagnosis of pneumonia requires microbiologic testing with a combination of complimentary tests. Recent advances include the commercial availability of syndromic multiplex PCR panels designed to detect the most common causes of bacterial and viral pneumonia along with selected antibiotic resistance genes, host biomarker tests, and immune gene expression signatures that can help separate infection from noninfectious inflammation as well as differentiate viral from bacterial processes. Current society guidelines do not yet address the use of new diagnostics. This article summarizes the advantages and limitations of new laboratory diagnostics for pneumonia and discusses potential use cases.
