[Current epidemiology of microbial low respiratory tract infections]

Area of Science:

• Respiratory Medicine
• Infectious Diseases
• Microbiology

Context:

• Pneumonia and acute bronchitis literature review reveals fragmented studies within established bacterial prevalence intervals.
• Germ occurrence in respiratory infections varies geographically and temporally.
• Commonly identified pathogens include Streptococcus pneumoniae, Influenza A, Mycoplasma pneumoniae, Haemophilus influenzae, and Legionella pneumophila.

Purpose:

• To review current literature on the epidemiology of pneumonia and acute bronchitis.
• To identify the most frequent bacterial and viral causative agents of pneumonia.
• To assess the clinical utility of diagnostic methods like PCR for respiratory infections.

Summary:

• Streptococcus pneumoniae is the most frequent cause of pneumonia in hospitalized patients, while Mycoplasma, Chlamydia, and viruses are more common in outpatients.
• Staphylococcus and Enterobacteriaceae are observed in elderly patients with comorbidities.
• Co-infections, often involving Streptococcus pneumoniae, are increasingly recognized, with the causal agent remaining unknown in 25-50% of cases.
• Methicillin-resistant Staphylococcus aureus has been identified.
• PCR has improved viral and atypical bacterial diagnosis, but its clinical relevance and epidemiological value are under scrutiny.
• Research on acute bronchitis epidemiology remains stagnant, while bacterial exacerbation of COPD focuses on Haemophilus influenzae's role.

Impact:

• Highlights the persistent challenges in identifying causative agents for pneumonia.
• Questions the routine clinical application of advanced diagnostic tools like PCR for respiratory infections.
• Underscores the need for further research into the epidemiology of acute bronchitis and the specific role of Haemophilus influenzae in COPD exacerbations.