Table 3 Etiology of pneumonia in β-lactam monotherapy and azithromycin combination therapy.

From: Azithromycin combination therapy for community-acquired pneumonia: propensity score analysis

Causative pathogenAll patientsβ-lactam monotherapyAzithromycin combination therapy
n = 1131 n (%)n = 952 n (%)n = 179 n (%)
Streptococcus pneumoniae240 (21.2)207 (21.7)33 (18.4)
Haemophilus influenzae91 (8.0)77 (8.0)14 (7.8)
Moraxella catarrhalis37 (3.3)30 (3.2)7 (3.9)
Methicillin-sensitive Staphylococcus aureus34 (3.0)31 (3.3)3 (1.7)
Streptococcus anginosus group27 (2.4)27 (2.8)0 (0)
Streptococcus spp.18 (1.6)17 (1.8)1 (0.6)
Klebsiella pneumoniae18 (1.6)15 (1.6)3 (1.7)
Anaerobes17 (1.5)16 (1.7)1 (0.6)
Pseudomonas aeruginosa15 (1.3)13 (1.4)2 (1.1)
Escherichia coli5 (0.4)4 (0.4)1 (0.6)
Corynebacterium spp.4 (0.4)3 (0.3)1 (0.6)
Acinetobacter spp.2 (0.2)2 (0.2)0 (0)
Methicillin-resistant Staphylococcus aureus2 (0.2)2 (0.2)0 (0)
Other pathogens8 (0.7)6 (0.6)2 (1.1)
Atypical pathogens+39 (3.4)20 (2.1)19 (10.6)
Chlamydophila pneumoniae23 (2.0)13 (1.4)10 (5.6)
Mycoplasma pneumoniae12 (1.1)7 (0.7)5 (2.7)
Legionella pneumophila2 (0.2)0 (0)2 (1.1)
Chlamydophila psittaci2 (0.2)0 (0)2 (1.1)
Unknown641 (56.7)535 (56.2)106 (59.2)
  1. There were 67 patients with multiple etiologies; therefore, the sum of the infection rates is over 100%.
  2. The other pathogens included influenza virus (2), Actinomyces spp. (1), Citrobacter koseri (1), Enterobacter aerogenes (1), Kocuria kristinae (1), Proteus mirabilis (1), and Veillonella spp. (1).
  3. §The atypical pathogens included Chlamydophila pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila and Chlamydophila psittaci.