Estimating the cost of antibiotic use on future collateral resistance: a retrospective comparison of cefuroxime versus cefazolin and amoxicillin/clavulanate

Background: Quantitative estimates of collateral resistance induced by antibiotic use are scarce. This study compared the effects of treatment with amoxicillin/clavulanate or cefazolin, compared to cefuroxime, on future resistance to ceftazidime among hospitalized patients. Methods: A retrospective analysis of patients with positive bacterial cultures hospitalized in an Israeli hospital during 2016-2019 was conducted. Patients were restricted to those treated with either amoxicillin/clavulanate, cefazolin, or cefuroxime and re-hospitalized with a positive bacterial culture during the following year. A 1:1 matching was performed for each patient in the amoxicillin/clavulanate and cefazolin groups, to a single patient from the cefuroxime group, yielding 185:185 and 298:298 matched patients. Logistic regression and g-formula (standardization) were used to estimate the odds ratio (OR), risk difference (RD), and number needed to harm (NNH). Results: Cefuroxime induced significantly higher resistance to ceftazidime than amoxicillin/clavulanate or cefazolin: the marginal OR was 1.76) 95%CI 1.16-2.83) compared to amoxicillin/clavulanate, and 1.98 (95%CI 1.41- 2.8) compared to cefazolin; The RD was 0.118 (95%CI 0.031-0.215) compared to amoxicillin/clavulanate, and 0.131 (95%CI 0.058-0.197) compared to cefazolin. We also estimated the NNH: replacing amoxicillin/clavulanate or cefazolin with cefuroxime would yield ceftazidime-resistance in one more patient for every 8.5 (95% CI 4.66-32.14) or 7.6 (95% CI 5.1-17.3) patients re-hospitalized in the following year. Conclusions: Our results indicate that treatment with amoxicillin/clavulanate or cefazolin is preferable to cefuroxime, in terms of future collateral resistance. The results presented here are a first step towards quantitative estimations of the ecological damage caused by different antibiotics.

Retrospective comparison of open vs minimally invasive cystotomy in 28 cats using a composite outcome score

Objectives The aim of this study was to compare the outcomes of cats undergoing open cystotomy with those undergoing minimally invasive surgery (MIS) for removal of cystic calculi by use of a composite outcome score. Methods Twenty-eight cats were retrospectively enrolled and divided into two groups: open cystotomy (n = 14) and MIS (n = 14). The primary outcome measure was a composite outcome score, including three variables: pain scores ⩾2 at either 6 or 12 h postoperatively; failure to remove all stones as determined by postoperative radiographs; and postoperative complications requiring a visit to the hospital separate from the planned suture removal appointment. Other data collected included signalment, history, other procedures performed during anesthesia, willingness to eat the day after surgery and the financial cost of the procedures. Results There was no significant difference in age, weight, sex or breed between the two groups. The risk of experiencing the composite outcome was 3/14 (21.4%) in the MIS group and 10/14 (71%) in the open procedure group ( P = 0.02). The cats in the open surgery group had 8.3 times greater odds of developing the composite outcome than cats in the MIS group (odds ratio 8.3, 95% confidence interval 1.3–74.4; P = 0.02). In the MIS group, 10/14 cats were eating the day after surgery vs 3/14 in the open procedure group ( P = 0.02). The procedural cost was higher in the MIS group, with a median cost of US$945 (interquartile range [IQR] US$872–1021) vs US$623 (IQR US$595–679) in the open group ( P <0.01). Conclusions and relevance In this study the composite outcome score provided evidence to support the use of MIS techniques in cats with cystic calculi. The composite outcome score should be considered in future veterinary studies as a promising method of assessing clinically relevant outcomes.