Atypical pneumonia (Review)

Georgakopoulou,Vasiliki Epameinondas; Lempesis,Ioannis G.; Tarantinos,Kyriakos; Sklapani,Pagona; Trakas,Nikolaos; Spandidos,Demetrios A.

doi:10.3892/etm.2024.12713

Atypical pneumonia (Review)

Authors:
- Vasiliki Epameinondas Georgakopoulou
- Ioannis G. Lempesis
- Kyriakos Tarantinos
- Pagona Sklapani
- Nikolaos Trakas
- Demetrios A. Spandidos
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Affiliations: Department of Pathophysiology, Laiko General Hospital, Medical School of National and Kapodistrian University of Athens, 11527 Athens, Greece, First Department of Respiratory Medicine, Sismanogleio Hospital, 15126 Athens, Greece, Department of Biochemistry, Sismanogleio Hospital, 15126 Athens, Greece, Laboratory of Clinical Virology, School of Medicine, University of Crete, 71003 Heraklion, Greece
Published online on: September 11, 2024 https://doi.org/10.3892/etm.2024.12713
Article Number: 424
Copyright: © Georgakopoulou et al. This is an open access article distributed under the terms of Creative Commons Attribution License.

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Abstract

Atypical pneumonia encompasses diverse pathogens, such as Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella species, which differ from typical bacterial pneumonia in their extrapulmonary manifestations. Clinical differentiation relies on systemic involvement rather than on standalone symptoms. Despite challenges in distinct diagnosis, syndromic approaches and weighted point systems aid in accurate presumptive diagnoses. Antibiotic treatment, often non‑β‑lactams due to the unique cell structures of atypical pathogens, targets intracellular processes. Macrolides, tetracyclines, quinolones and ketolides are effective due to their intracellular penetration, crucial for combating these intracellular pathogens. The prevalence of atypical pneumonia varies globally, with Europe, Asia/Africa and Latin America reporting detection rates between 20‑28%. Streptococcus pneumoniae remains a primary cause of pneumonia; however, atypical pathogens contribute significantly to this disease, being more prevalent in outpatient settings and among young adults. Legionella stands out in severe hospitalized cases and is associated with higher mortality rates. Diagnosis proves challenging due to overlapping symptoms with other respiratory infections. Differentiation among pathogens, such as Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella relies on subtle clinical variations and imaging findings. Diagnostic methods include serological studies, cultures and polymerase chain reaction, each with limitations in sensitivity or specificity. Prognosis varies widely. Atypical pneumonia can progress to severe forms with fatal outcomes, causing multi‑organ damage. Complications extend beyond the respiratory system, affecting the cardiovascular system, exacerbating conditions such as chronic obstructive pulmonary disease and asthma, and potentially linking to conditions such as lung cancer. Increasing antibiotic resistance poses a significant challenge, influencing treatment outcomes and prolonging illness duration.

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