Question 20

What were the main differences between individual fluoroquinolones in terms of activity against the most common respiratory pathogens?

Levofloxacin was the most active of the three fluoroquinolones with 100% activity against M. catarrhalis and S. aureus, 96.9% and 96.7% against S. pneumoniae and K. pneumoniae, 90.9% against A. baumannii, 85.7% against P. aeruginosa and 58.8% against E. coli (Table 5). In contrast, moxifloxacin could not be tested against A. baumannii, E. coli, M. catarrhalis and P. aeruginosa due to a lack of MIC breakpoints. The activity of moxifloxacin against other identified pathogens was comparable to that demonstrated by levofloxacin. In regard to ciprofloxacin, this agent demonstrated Gram-negative activity similar to levofloxacin, but was not considered as active against the important respiratory pathogen S. pneumoniae. Therefore, levofloxacin demonstrated a wider antibacterial spectrum than the other fluoroquinolones (Figure 3).

Table 5. Antibacterial susceptibility of common ABECOPD Asian pathogens to three fluoroquinolones

Agent		A. baumannii			E. coli			K. pneumoniae			M. catarrhalis			P. aeruginosa			S. aureus			S. pneumoniae
		%R	%I	%S	%R	%I	%S	%R	%I	%S	%R	%I	%S	%R	%I	%S	%R	%I	%S	%R	%I	%S
Levofloxacin		4.5	4.5	90.9	35.3	5.9	58.8	1.1	2.2	96.7	0	0	100	9.5	4.8	85.7	0	0	100	3.1	0	96.9
Ciprofloxacin		9.1	4.5	86.4	41.2	0	58.8	3.3	2.2	94.5	0	0	100	9.5	4.8	85.7	0	0	100
Moxifloxacin								0	0	100							0	0	100	0	3.1	96.9
Abbreviations: ABECOPD = acute bacterial exacerbations of chronic obstructive pulmonary disease, A. baumannii = Acinetobacter baumannii, E. coli = Escherichia coli, K. pneumoniae = Klebsiella pneumoniae, M. catarrhalis = Moraxella catarrhalis, P. aeruginosa = Pseudomonas aeruginosa, S. aureus = Staphylococcus aureus, S. pneumoniae = Streptococcus pneumoniae, %R = percent resistant, %I = percent intermediate-resistant, %S = percent susceptible. Adapted from reference (16).

Figure 3. Antibacterial susceptibility of three fluoroquinolones against Asian ABECOPD pathogens

Adapted from reference (16).