Question 21

Were any differences identified in regard to bacterial susceptibility to levofloxacin compared with non-fluoroquinolone agents?

The antibacterial susceptibility of the pathogens was assessed for a range of agents, including penicillin, amoxicillin/clavulanate, macrolides and cephalosporins. Levofloxacin was the most active agent with the widest spectrum of antibacterial activity (Table 6). Cefuroxime was more active than levofloxacin against E. coli, but against all other pathogens levofloxacin was superior or equal to amoxicillin/clavulanate, cefuroxime, clarithromycin, trimethoprim-sulfamethoxazole (TMP-SMX) and penicillin (Figure 4).
It is important to remember that P. aeruginosa and other Gram-negatives are more common in patients with frequent exacerbations and that many of these organisms are resistant to traditional first-line agents resulting in the recommendation that ciprofloxacin and high-dose levofloxacin be used as the agent of choice when these pathogens are identified in patients with acute exacerbations of chronic bronchitis (AECB) (18).

Table 6. Antibacterial susceptibility of common ABECOPD pathogens to levofloxacin and non-fluoroquinolone comparator antimicrobials

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
Amoxicillin/					23.5	29.4	47.1	3.3	2.2	94.5	0	0	100				0	0	100	3.1	0	96.9
clavulanate
Cefuroxime					17.6	0	82.4	2.2	3.3	94.5	0	0	100		0	0	0	0	100	21.9	9.4	68.8
Clarithromycin											0	0	100				0	0	100	50	3.1	46.9
TMP-SMX		18.2	0	81.8	52.9	0	47.1	7.7	0	92.3	9.5	47.6	42.9	77.8	0	22.2	0	0	100	21.9	12.5	65.6
Penicillin																	60	0	40	18.8	34.4	46.9
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, TMP-SMX = trimethoprim-sulfamethoxazole. Adapted from reference (16).

Figure 4. Susceptibility of ABECOPD pathogens to different antimicrobials

Adapted from reference (16).