UK: Doxycycline is efficient in treating mild-to-moderate community-acquired pneumonia (CAP) in adults, states a study article published in the Clinical Infectious Diseases. The efficacy of doxycycline was found to be comparable to macrolides or fluoroquinolones.
Pneumonia is a very common respiratory infection caused by fungi, bacteria, or viruses. It affects approximately 450 million people a year, globally. Pneumonia, contracted by a person outside of the healthcare system is termed Community-acquired pneumonia (CAP). It is a major cause of morbidity and mortality worldwide.

Streptococcus pneumoniae, influenza A, Mycoplasma pneumonia, and Chlamydophila pneumonia are the main causative pathogens, and age, smoking and comorbidities act as dominant risk factors for CAP. In patients with community-acquired pneumonia (CAP), antibiotics are usually chosen empirically to treat the most likely causative organisms until a microbiologic cause is identified. Doxycycline, abroad-spectrum tetracycline-class antibiotic has a high degree of activity against many common respiratory pathogens. Doxycycline has been recommended as a treatment option for non-severe community-acquired pneumonia (CAP) in adults.
Sang Ho Choi, University College London, London, UK, and colleagues conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) of doxycycline versus comparator to assess the clinical efficacy of doxycycline in adult patients with mild-to-moderate community-acquired pneumonia.
Researchers searched the databases and included six RCTs with 834 clinically evaluable patients. The trials were performed between 1984 and 2004. Comparators were three macrolides (roxithromycin, spiramycin, and erythromycin) and three fluoroquinolones (ofloxacin, fleroxacin, and levofloxacin). The primary outcome was the clinical cure rate. Random effects model meta-analyses were used to generate pooled odds ratio (OR) and evaluate heterogeneity (I2). The risk of bias (RoB) and quality of evidence (QoE) was evaluated using the Cochrane Risk of Bias 2.0 tool and GRADE methods, respectively.
Key findings of the study,
• Four trials had an overall high RoB.
• The clinical cure rate was similar between the doxycycline and comparator groups (87.2% vs. 82.6%; OR 1.29).
• Subgroup analysis of two studies with a low RoB showed significantly higher clinical cure rates in the doxycycline group (87.1% vs. 77.8%; OR 1.92).
• Adverse event rates were comparable between the doxycycline and comparator groups.
The authors conclude that the study results showed doxycycline to be equally efficient in mild-to-moderate CAP as macrolides or fluoroquinolones. Taking into consideration the absence of any recent trials, future large-scale clinical trials are needed.
Reference:
Sang Ho Choi, Antoni Cesar, Timothy Arthur Chandos Snow, Naveed Saleem, Nishkantha Arulkumaran, Mervyn Singer, Efficacy of Doxycycline for Mild-to-moderate Community-acquired Pneumonia in Adults: A Systematic Review and Meta-analysis of Randomized Controlled Trials, Clinical Infectious Diseases, 2022;, ciac615, https://doi.org/10.1093/cid/ciac615