There are few data comparing the relative effectiveness of the individual β-lactams.
The objective of the study was to quantify the reduced effectiveness, defined as switching to a different antibiotic being prescribed for the same indication, among new users of β-lactam antibiotics in primary care.
A retrospective cohort study was conducted using the Health Search Database, an Italian primary care data source.
Patients newly prescribed with β-lactams for a specific indication between 1 January 2013 and 31 December 2017 were identified.
A switch to a different antibiotic for the same indication occurring during a 30day follow-up was the study outcome.
Among 178 256 patients newly treated with β-lactam antibiotics, 1172 ( 0.65% ) switched to a different antibiotic.
Amoxicillin / Clavulanate ( co-AmoxiClav, Augmentin: n = 104 891 ) and Amoxicillin ( n = 21 699 ) were the most frequently prescribed β-lactams.
The other antibiotics have shown significantly higher risk of switching when compared with co-AmoxiClav for lower respiratory tract [ e.g. Ceftriaxone, hazard ratio ( HR ): 1.6, 95% CI: 1.2-2.0 ], dental [ e.g. Amoxicillin, HR: 4.2, 95% CI: 2.9-5.9 ], and middle ear infections [ e.g. Amoxicillin, HR: 1.8, 95% CI: 1.1-2.7 ].
The same results were gathered when parenteral formulations were excluded.
In conclusion, the prevalence of reduced effectiveness of newly prescribed β-lactam antibiotics was lower than 1%.
Specifically, the rate of switch to another antibiotic, when it was prescribed to treat low respiratory tract, dental, and middle ear infections, was lower among users of co-amoxiclav than those prescribed with other β-lactams. ( Xagena )
Lapi F et al, J Antimicrob Chemother 2021;76:2186-2194