What Is the Appropriate Use of Antibiotics In Acute Exacerbations of COPD?

Current clinical guidelines vary slightly in their recommendations regarding when to give antibiotics in AECOPD (see Table 1). However, existing evidence favors antibiotic treatment for those patients presenting with two or three cardinal symptoms, specifically those with increased sputum purulence, and those with severe disease (i.e. pre-existing advanced airflow obstruction and/or exacerbations requiring mechanical ventilation). Conversely, studies have shown that many patients, particularly those with milder exacerbations, experience resolution of symptoms without antibiotic treatment.^11,18

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Table 2. Targeted antibiotic therapy in AECOPD

Antibiotic Choice in AECOPD

Risk stratification. In patients likely to benefit from antibiotic therapy, an understanding of the relationship between severity of COPD, host risk factors for poor outcomes, and microbiology is paramount to guide clinical decision-making. Historically, such bacteria as Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis have been implicated in the pathogenesis of AECOPD.^3,7 In patients with simple exacerbations, antibiotics that target these pathogens should be used (see Table 2).

However, patients with more severe underlying airway obstruction (i.e. FEV1<50%) and risk factors for poor outcomes, specifically recent hospitalization (≥2 days during the previous 90 days), frequent antibiotics (>3 courses during the previous year), and severe exacerbations are more likely to be infected with resistant strains or gram-negative organisms.^3,7 Pseudomonas aeruginosa, in particular, is of increasing concern in this population. In patients with complicated exacerbations, more broad-coverage, empiric antibiotics should be initiated (see Table 2).

With this in mind, patients meeting criteria for treatment must first be stratified according to the severity of COPD and risk factors for poor outcomes before a decision regarding a specific antibiotic is reached. Figure 1 outlines a recommended approach for antibiotic administration in AECOPD. The optimal choice of antibiotics must consider cost-effectiveness, local patterns of antibiotic resistance, tissue penetration, patient adherence, and risk of such adverse drug events as diarrhea.

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Figure 1. Approach to antibiotic administration in AECOPD

Comparative effectiveness. Current treatment guidelines do not favor the use of any particular antibiotic in simple AECOPD.^3,4,5,6 However, as selective pressure has led to in vitro resistance to antibiotics traditionally considered first-line (e.g. doxycycline, trimethoprim/sulfamethoxazole, amoxicillin), the use of second-line antibiotics (e.g. fluoroquinolones, macrolides, cephalosporins, β-lactam/ β-lactamase inhibitors) has increased. Consequently, several studies have compared the effectiveness of different antimicrobial regimens.

One meta-analysis found that second-line antibiotics, when compared with first-line agents, provided greater clinical improvement to patients with AECOPD, without significant differences in mortality, microbiologic eradication, or incidence of adverse drug events.²⁰ Among the subgroup of trials enrolling hospitalized patients, the clinical effectiveness of second-line agents remained significantly greater than that of first-line agents.

Another meta-analysis compared trials that studied only macrolides, quinolones, and amoxicillin-clavulanate and found no difference in terms of short-term clinical effectiveness; however, there was weak evidence to suggest that quinolones were associated with better microbiological success and fewer recurrences of AECOPD.²¹ Fluoroquinolones are preferred in complicated cases of AECOPD in which there is a greater risk for enterobacteriaceae and Pseudomonas species.^3,7

Antibiotic Duration

The duration of antibiotic therapy in AECOPD has been studied extensively, with randomized controlled trials consistently demonstrating no additional benefit to courses extending beyond five days. One meta-analysis of 21 studies found similar clinical and microbiologic cure rates among patients randomized to antibiotic treatment for ≤5 days versus >5 days.²² A subgroup analysis of the trials evaluating different durations of the same antibiotic also demonstrated no difference in clinical effectiveness, and this finding was confirmed in a separate meta-analysis.^22,23