Bacterial Pneumonia – pneumonia caused by a bacterial pathogen, most commonly (around 50% of bacterial pneumonia cases) by Streptococcus pneumoniae, which generally abides asymptomatically in the human upper respiratory tract. Bacterial pneumonia typically infects more than 900,000 Americans yearly who become symptomatic after an upper respiratory viral cold or flu. Other common bacteria causing bacterial pneumonia include Mycoplasma pneumoniae, Chlamydophila pneumoniae, Haemophilus influenzae (the bacteria), and Legionella pneumophila.
Viral Pneumonia – Is, of course, caused by a virus or viruses. Roughly one-third of all pneumonia cases are viral. Certain viruses are associated with causing pneumonia, mostly on an opportunistic basis. The more common ones include Respiratory syncytial virus (RSV), Influenza virus, Parainfluenza virus, Adenovirus, Measles virus, and Coronaviruses (of which there are several), including SARS-CoV-2, the virus that causes COVID-19.
Fungal Pneumonia – While more common outside the United States, fungal spores will attempt to grow wherever they find favorable conditions. In the southwestern U.S., the valley fever fungus, Coccidioides, is a frequent respiratory pathogen. Other common fungal pneumonias include Histoplasma capsulatum (histoplasmosis), Pneumocystis jirovecii (aka, Pneumocystis pneumonia, associated primarily with the immunocompromised), Blastomyces fungi, and Cryptococcus neoformans. Fungal pneumonia is a real threat to the immune-compromised. If your coughing client falls into that category, be sure fungal pathogens are investigated.
Chemical Pneumonia – Any chemical irritant can provoke pneumonia when it inflames the lungs. Remember, pneumonia is about inflammation, not just infection. Chemical weapons, gases, pool cleaning chemicals, and the volatiles used in air fresheners are examples of inhaled chemical irritants. Dr. Raymond Casciari, pulmonologist, offers a great rule of thumb for suspecting chemical pneumonia in a 2021 interview with Health magazine. "If your eyes are burning, your lungs are too."
Aspiration Pneumonia- Aspiration, or entry of unwanted substances into the lower airway passages and lungs, is one of the most common complications following general surgery. Also, 5 to 15% of all CAPs are traced back to aspiration, with 18% of retirement care clients experiencing aspiration-induced pneumonia at some point. Weakness or failure of the epiglottis, which closes the laryngeal inlet during swallowing protecting the airways, or an abnormal cough reflex are prime factors in aspiration. Most incidents of aspiration result in chemical pneumonitis, or irritation and inflammation of lung tissues caused by an inhaled particulate, and never reach the severity of chemical or infectious pneumonia. When it does, mortality rates can reach as high as 71%. Bacteria establishes its presence quickly, so interventions are needed. Aspiration pneumonia can be considered both a chemically induced pneumonia and an opportunistic infection of the lungs. Inflammatory pulmonary processes occur after abnormal entry of fluids into the lower respiratory tract. The aspirated fluid can be oropharyngeal secretions, particulate matter, or gastric content. The inhaling of inflammation-generating secretions into the lungs is a significant event for a ready pathogen, typically bacterial, to proliferate (Sanivarapu et al., 2022; Sanivarapu & Gibson, 2022; Klompas, 2022).
Parasitic Pneumonia – is the least common of the major pneumonia types. Parasites are all around us, and in us, not just for those living in tropical areas. Typically, pneumonia-causing parasites start somewhere else on or in the body and migrate into the lungs later. Common parasitic types of pneumonia are Toxoplasma gondii (toxoplasmosis), Plasmodium malariae, and Paragonimus westermani, the Asian lung fluke.