Measuring the comparative efficacy of antibacterial agents for acute otitis media: The “Pollyanna phenomenon”

Assumed versus Approved Breakpoints

“…Most of the isolates for which the MICs of cefaclor were Յ0.5 g/ml were penicillin susceptible. Bacteriologic failure rates for patients with H. influenzae infections in these studies were 38.9 and 55.2%, which are similar to results expected with a placebo (8,9). Based on these data, the susceptibility breakpoint for cefaclor appears to be between Յ0.5 g/ml (the MICs for isolates from patients with good response to cefaclor therapy) and Ͼ0.5 g/ml (the MICs for penicillin-nonsusceptible S. pneumoniae and for H. influenzae).…”

“…The fact that the concentration of an antimicrobial agent had to exceed the in vitro inhibitory or lethal concentration of the agent to be effective was first documented by Eagle and colleagues almost 50 years ago (7), and the dynamics of this relationship was first demonstrated in animal models by Vogelman et al in 1988 (15). It has come to the attention of many workers in the field of oral antimicrobial agents and bacterial respiratory tract infections that many of the breakpoints used to classify the susceptibilities of S. pneumoniae and H. influenzae to oral agents do not correspond with clinical and bacteriological outcomes of infections such as otitis media, sinusitis, and acute exacerbations of chronic bronchitis (1)(2)(3)(4)9). Many of these breakpoints are actually higher than peak concentrations of the agents in serum and tissue, so that clinically achievable concentrations can never reach, let alone exceed, the concentrations needed to inhibit organisms for which the MICs are at or close to the susceptibility breakpoint values.…”

“…This statement is not substantiated by any peer-reviewed papers. Many authors have questioned this "conventional wisdom" approach to medicine, and recommend that decisions be made on the basis of sound scientific evidence using adequately designed studies (9,13). In a 1993 review, Klein summarized bacteriologic outcomes reported in acute otitis media studies and noted that the bacteriologic failure rate of cefaclor in S. pneumoniae infections varied from 2.7 to 52.9%, with an overall failure rate of 18.2% (8).…”

Updated guideline for the management of upper respiratory tract infections in South Africa: 2008

“…Studies in which efficacy of antibiotics used for AOM is measured by symptomatic relief, fail to discern major differences between drugs because of the so-called 'Pollyanna phenomenon': drugs with poor in vivo activity appear to be effective because of the high rate (67%) of spontaneous recovery of the infection. 21 Given the high rate of spontaneous resolution of AOM, and the probable viral aetiology, particularly in older infants, some authorities argue that antibiotics should be deferred for at least 48 hours during which the patient is given analgesics and decongestants. 22 A useful approach may be to dispense the antibiotic or provide a prescription, with the instruction that it is to be given (or the prescription filled) if there has not been resolution by 48 hours.…”

Fluoroquinolones compared with -lactam antibiotics for the treatment of acute bacterial sinusitis: a meta-analysis of randomized controlled trials

“…7,[38][39][40] In fact, in this meta-analysis, the pooled percentage of patients with bacteriologically documented disease in the trials in which relevant studies were performed was 54%. Additional factors that may confound the assessment of effectiveness of the studied treatments include the potential for sinusitis-like symptoms to persist despite bacteriologic cure 7,38,39 and the likelihood of unbalanced use of symptom-relief medications among different treatment groups. 41 In this regard, the greater bacteriologic success exhibited with respiratory fluoroquinolones relative to β-lactams may be important.…”