High-dose versus standard-dose amoxicillin/clavulanate for clinically-diagnosed acute bacterial sinusitis: A randomized clinical trial

High-Dose vs Standard-Dose Amoxicillin Plus Clavulanate for Adults With Acute Sinusitis: A Randomized Clinical Trial

IMPORTANCE

Acute bacterial sinusitis is common, but currently recommended antibiotic treatment provides minimal benefit.

OBJECTIVE

To confirm the previous finding that high-dose amoxicillin plus clavulanate (with double the amount of amoxicillin) may be superior to standard-dose amoxicillin plus clavulanate in adults.

DESIGN, SETTING, AND PARTICIPANTS

This double-blind, comparative-effectiveness randomized clinical trial was conducted from February 26, 2018, through May 10, 2020, at the academic primary care internal medicine and pediatrics practice of Albany Medical Center, located in Cohoes, New York. Participants included adults aged 18 years or older who were prescribed amoxicillin plus clavulanate for acute bacterial sinusitis diagnosed in accordance with the Infectious Diseases Society of America guidelines.

INTERVENTIONS

Amoxicillin 875 mg with clavulanate 125 mg plus either placebo (standard dose) or amoxicillin 875 mg (high dose) twice a day for 7 days.

MAIN OUTCOMES AND MEASURES

The primary efficacy outcome was a global rating of "a lot better" or "no symptoms" at the end of 3 days of treatment using a Global Rating of Improvement scale, with outcomes ranging from 1 (a lot worse) to 6 (no symptoms). The primary adverse effect outcome was severe diarrhea at 3 or 10 days after the start of treatment.

RESULTS

At an unplanned interim analysis prompted by COVID-19 restrictions, 157 of a projected 240 participants had been enrolled (mean age, 48.5 [range, 18.7-84.0] years; 117 women [74.5%]), with 79 randomized to the standard dose and 78 to the high dose; 9 and 12, respectively, withdrew or were lost to follow-up before the assessment of the primary outcome. At day 3, 31 of 70 participants (44.3%) in the standard-dose group reported a global rating of "a lot better" or "no symptoms," as did 24 of 66 (36.4%) in the high-dose group, for a difference of -7.9% (95% CI, -24.4% to 8.5%; P = .35). The study was, therefore, stopped for futility. Diarrhea was common in both groups by day 3, with any diarrhea reported in 29 of 71 participants (40.8%) receiving the standard dose and 28 of 65 (43.1%) receiving the high dose and severe diarrhea reported in 5 of 71 (7.0%) and 5 of 65 (7.7%), respectively.

CONCLUSIONS AND RELEVANCE

The results of this randomized clinical trial suggest that adults treated for clinically diagnosed acute sinusitis did not appear to benefit from taking high-dose compared with standard-dose amoxicillin plus clavulanate.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03431337.

In vitro Combined Inhibitory Activities of β-Lactam Antibiotics and Clavulanic Acid Against bla KPC-2-Positive Klebsiella pneumoniae

Background

The spread of KPC-producing Enterobacteriaceae has triggered a global public health concern, with KPC-2-positive strains being the most prevalent in China. We hereby studied the in vitro combined inhibitory activities of three kinds of β-lactam antibiotics and clavulanic acid at different concentrations against bla_KPC-2-positive Klebsiella pneumoniae to explore the antimicrobial characteristics of these combinations and alternative therapeutic regimens for infections caused by bla_KPC-2-positive K. pneumoniae strains.

Materials and Methods

In this study, 153 clinically isolated bla_KPC-2-positive K. pneumoniae strains from 19 provinces in China were collected from 2016 to 2018. Antimicrobial susceptibility testing of imipenem/clavulanic acid, meropenem/clavulanic acid, ceftazidime/clavulanic acid, and each antimicrobial agent alone was performed by broth microdilution technique according to the CLSI guidelines. The concentration ratios of β-lactam antibiotics to clavulanic acid were as follows: 1:1, 1:2, 1:4, 1:8, 1:16, 1:32. The antimicrobial susceptibility of the combinations was determined according to the breakpoints of Imipenem, meropenem, and ceftazidime established by the CLSI directives for Enterobacteriaceae.

Results

The MICs of all three combinations gradually declined with increments in the proportion of clavulanic acid in the regimens, and the most significant decline in the MIC₅₀ and MIC₉₀ was seen in combinations at the concentration ratio of 1:1 (also 1:2 for meropenem/clavulanic acid). When the concentration of clavulanic acid was restricted to 4 mg/L, the susceptibility of more than 70% of the isolates to the regimens could be restored with imipenem MIC 2–4 mg/L, meropenem MIC 2–8 mg/L or ceftazidime MIC 8mg/L. However, the percentage decreased to 30 to 40% when the initial MIC level was higher.

Conclusion

The highest combined inhibitory activity of β-lactam antibiotics/clavulanic acid at low concentration ratios against bla_KPC-2-positive K. pneumoniae may offer a new way to optimize the effects of these antimicrobial regimens.