A nurse-driven penicillin allergy risk score in the preoperative setting was associated with increased cefazolin use perioperatively.

STUDY OBJECTIVE: To characterize and assess the effects of a preoperative, nurse-driven penicillin allergy risk stratification tool on rates of perioperative cefazolin and second-line antibiotic use. DESIGN: Quasi-experimental quality improvement study of penicillin-allergic surgical patients undergoing procedures for which cefazolin is indicated. SETTING: Outpatient Perioperative Care Clinic (PCC) for preoperative surgical patients at a tertiary care center. PATIENTS: 670 and 1371 adult penicillin-allergic PCC attendants and non-attendants, respectively. INTERVENTION: A paper penicillin allergy risk stratification questionnaire was administered during the PCC visit. Nurses were educated on its use. MEASUREMENTS: Antibiotic (cefazolin, clindamycin, vancomycin) use rates in the 24 months before and 17 months after intervention implementation in November 2020 (November 2018 - April 2022) were assessed in penicillin-allergic PCC attendants with statistical process control charts. Multivariable logistic regression assessed antibiotic use rates pre- and post-intervention adjusting for age, sex, surgical specialty and penicillin allergy history severity. Similar analyses were done in penicillin-allergic PCC non-attendants. MAIN RESULTS: Of 670 penicillin-allergic PCC attendants, 451 (median [IQR] age, 66 (Sousa-Pinto et al., 2021 [14])) were analyzed pre-intervention and 219 (median [IQR] age, 66 (Mine et al., 1970 [13])) post-intervention. One month after implementation, process measures demonstrated an upward shift in cefazolin use for PCC attendants versus no shift or other special cause variation for PCC non-attendants. There were increased odds of cefazolin use (aOR 1.67, 95% CI [1.09-2.57], P = 0.019), decreased odds of clindamycin use (aOR 0.61, 95% CI [0.42-0.89], P = 0.010) and decreased odds of vancomycin use (aOR 0.56, 95% CI [0.35-0.88], P = 0.013) in PCC attendants post-intervention. This effect did not occur in PCC non-attendants. There was no increase in perioperative anaphylaxis post-intervention. CONCLUSIONS: A simple penicillin allergy risk stratification tool implemented in the preoperative setting was associated with increased use of cefazolin and decreased rates of second-line agents post implementation.

Examining cefazolin utilization and perioperative anaphylaxis in patients with and without a penicillin allergy label: A cross-sectional study.

STUDY OBJECTIVE: To compare the occurrence of cefazolin perioperative anaphylaxis (POA) in patients with and without a penicillin allergy label (PAL) to determine whether the prevalence of cefazolin POA differs based on the presence of a PAL. DESIGN: Cross-sectional study. SETTING: A large U.S. healthcare system in the Baltimore-D.C. region, July 2017 to July 2020. PATIENTS: 112,817 surgical encounters across inpatient and outpatient settings in various specialties, involving 90,089 patients. Of these, 4876 (4.3%) encounters had a PAL. INTERVENTIONS: Perioperative cefazolin administration within 4 h before surgery to 4 h after the procedure began. MEASUREMENTS: The primary outcome was cefazolin POA in patients with and without PALs. Potential POA cases were identified based on tryptase orders or diphenhydramine administrations within the initial cefazolin administration to 6 h postoperatively. Verification included two validation steps. The first checked for hypersensitivity reaction (HSR) documentation, and the second, led by Allergy specialists, identified POA and the probable culprit. The secondary outcome looked at cefazolin use trends in patients with a PAL, stratified by setting and specialty. MAIN RESULTS: Of 112,817 encounters, 1421 (1.3%) had possible cefazolin HSRs. Of these, 22 (1.5%) had POA, resulting in a 0.02% prevalence. Of these, 13 (59.1%) were linked to cefazolin and 9 (40.9%) attributed to other drugs. Only one cefazolin POA case had a PAL, indicating no significant difference in cefazolin POA prevalence between patients with and without PALs (p = 0.437). Perioperative cefazolin use in patients with PALs steadily increased from 2.6% to 6.0% between 2017 and 2020, specifically in academic settings. CONCLUSIONS: The prevalence of cefazolin POA does not exhibit significant differences between patients with and without PALs, and notably, the incidence remains remarkably low. Based on these findings, it is advisable to view cefazolin as an acceptable choice for prophylaxis in patients carrying a PAL.

Are changes in antibiotic prophylaxis recommendations responsible for an increased risk of cefazolin allergy?

BACKGROUND: The first line of prevention of surgical site infection relies on the timely administration of antibiotic prophylaxis. First- and second-generation cephalosporins are the most recommended antibiotics in elective surgery. The incidence of cefazolin allergy has increased worldwide over the years. The sensitization mechanism of cefazolin is currently unknown, and data supporting cross-reactivity between penicillins and cephalosporins are lacking. Sensitization could occur through previous exposure either to cefazolin or to structurally related chemical agents. The objective of this study was to evaluate sensitization agents towards cefazolin. METHODS: The OpenBabel chemoinformatics toolbox was used to search for similarities between cefazolin and other molecules in an extensive drug database. Using the pholcodine-rocuronium similarity score as a threshold, we selected drugs with the most similar structure to that of cefazolin. Exposure to those drugs and cefazolin was assessed in a cohort of patients with skin test-proven cefazolin allergy at a specialized allergy centre via a self-administered anonymous questionnaire. RESULTS: Using the pholcodine-rocuronium similarity score as a threshold (score≥0.7), 42 molecules were found to be similar to cefazolin (all cephalosporins). Only 8 were marketed in France. None of the 14 cefazolin-allergic patients who answered the questionnaire (65% female, median age 56 years) reported exposure to any identified antibiotics. In contrast, 11 (78%) had at least one previous surgery requiring cefazolin before the index case. CONCLUSION: Direct previous cefazolin exposure was identified in 78% of cefazolin-allergic patients. Cefazolin started to take a central place in antibiotic prophylaxis after 2010, when cefamandole usage decreased drastically. Changes in antibiotic prophylaxis over the past 14 years in France could have been the turning point for the increased incidence of cefazolin allergy.

Prospective assessment of the frequency of and risk factors for bleeding events in patients treated with cefazolin.

PURPOSE: Major bleedings have been described with cefazolin. The objective was to determine the frequency of bleeding events in cefazolin-treated patients and to identify risk factors for these complications. METHODS: Monocenter prospective observational study of all consecutive cefazolin-treated patients. Patients benefited from a daily clinical assessment of bleedings and a twice-a-week blood sampling including hemostasis. Bleedings were classified according to the International Society on Thrombosis and Hemostasis classification: major, clinically relevant non-major bleedings (CRNMB) and minor bleedings. RESULTS: From September 2019 to July 2020, 120 patients were included, with a mean age of 59.4 (± 20.7) years; 70% of them (84/120) were men. At least 1 CRNMB or major bleeding were observed in 10% of the patients (12/120). Compared to patients with no or minor bleeding, patients with CRNMB or major bleeding were, upon start of cefazolin, more frequently hospitalized in an intensive care unit (7/12, 58.3%, vs. 12/108, 11.1%, P < 0.001, respectively) and receiving vitamin K antagonists (4/12, 33.3%, vs. 8/108, 7.4%, P = 0.019, respectively). After multivariate analysis, patients receiving vitamin K antagonists the day prior bleeding and/or treated for endocarditis were factors associated with an increased risk of CRNMB or major bleeding (odd ratio 1.36, confidence interval 95%, 1.06-1.76, P = 0.020 and 1.30, 1.06-1.61, P = 0.015, respectively). CONCLUSIONS: Bleeding events associated with cefazolin treatment are frequent. Close clinical monitoring should be performed for patients treated for endocarditis and/or receiving vitamin K antagonists. Hemostasis work-up could be restricted to these patients.

Contemporary use of cefazolin for MSSA infective endocarditis: analysis of a national prospective cohort.

OBJECTIVES: This study aimed to assess the real use of cefazolin for methicillin-susceptible Staphylococcus aureus (MSSA) infective endocarditis (IE) in the Spanish National Endocarditis Database (GAMES) and to compare it with antistaphylococcal penicillin (ASP). METHODS: Prospective cohort study with retrospective analysis of a cohort of MSSA IE treated with cloxacillin and/or cefazolin. Outcomes assessed were relapse; intra-hospital, overall, and endocarditis-related mortality; and adverse events. Risk of renal toxicity with each treatment was evaluated separately. RESULTS: We included 631 IE episodes caused by MSSA treated with cloxacillin and/or cefazolin. Antibiotic treatment was cloxacillin, cefazolin, or both in 537 (85%), 57 (9%), and 37 (6%) episodes, respectively. Patients treated with cefazolin had significantly higher rates of comorbidities (median Charlson Index 7, P <0.01) and previous renal failure (57.9%, P <0.01). Patients treated with cloxacillin presented higher rates of septic shock (25%, P = 0.033) and new-onset or worsening renal failure (47.3%, P = 0.024) with significantly higher rates of in-hospital mortality (38.5%, P = 0.017). One-year IE-related mortality and rate of relapses were similar between treatment groups. None of the treatments were identified as risk or protective factors. CONCLUSION: Our results suggest that cefazolin is a valuable option for the treatment of MSSA IE, without differences in 1-year mortality or relapses compared with cloxacillin, and might be considered equally effective.

Trial of Vancomycin and Cefazolin as Surgical Prophylaxis in Arthroplasty.

BACKGROUND: The addition of vancomycin to beta-lactam prophylaxis in arthroplasty may reduce surgical-site infections; however, the efficacy and safety are unclear. METHODS: In this multicenter, double-blind, superiority, placebo-controlled trial, we randomly assigned adult patients without known methicillin-resistant Staphylococcus aureus (MRSA) colonization who were undergoing arthroplasty to receive 1.5 g of vancomycin or normal saline placebo, in addition to cefazolin prophylaxis. The primary outcome was surgical-site infection within 90 days after surgery. RESULTS: A total of 4239 patients underwent randomization. Among 4113 patients in the modified intention-to-treat population (2233 undergoing knee arthroplasty, 1850 undergoing hip arthroplasty, and 30 undergoing shoulder arthroplasty), surgical-site infections occurred in 91 of 2044 patients (4.5%) in the vancomycin group and in 72 of 2069 patients (3.5%) in the placebo group (relative risk, 1.28; 95% confidence interval [CI], 0.94 to 1.73; P = 0.11). Among patients undergoing knee arthroplasty, surgical-site infections occurred in 63 of 1109 patients (5.7%) in the vancomyin group and in 42 of 1124 patients (3.7%) in the placebo group (relative risk, 1.52; 95% CI, 1.04 to 2.23). Among patients undergoing hip arthroplasty, surgical-site infections occurred in 28 of 920 patients (3.0%) in the vancomyin group and in 29 of 930 patients (3.1%) in the placebo group (relative risk, 0.98; 95% CI, 0.59 to 1.63). Adverse events occurred in 35 of 2010 patients (1.7%) in the vancomycin group and in 35 of 2030 patients (1.7%) in the placebo group, including hypersensitivity reactions in 24 of 2010 patients (1.2%) and 11 of 2030 patients (0.5%), respectively (relative risk, 2.20; 95% CI, 1.08 to 4.49), and acute kidney injury in 42 of 2010 patients (2.1%) and 74 of 2030 patients (3.6%), respectively (relative risk, 0.57; 95% CI, 0.39 to 0.83). CONCLUSIONS: The addition of vancomycin to cefazolin prophylaxis was not superior to placebo for the prevention of surgical-site infections in arthroplasty among patients without known MRSA colonization. (Funded by the Australian National Health and Medical Research Council; Australian New Zealand Clinical Trials Registry number, ACTRN12618000642280.).

Antibiotic choice for Group B Streptococcus prophylaxis in mothers with reported penicillin allergy and associated newborn outcomes.

OBJECTIVE: To evaluate the choice of antibiotic used for intrapartum Group B Streptococcus (GBS) prophylaxis in pregnant individuals with reported penicillin allergies compared to those without reported penicillin allergies and investigate whether there are associated differences in neonatal outcomes. STUDY DESIGN: This retrospective cohort study included mother-infant dyads of GBS positive pregnant individuals who labored and delivered newborns ≥ 35 weeks of gestation at a high-volume urban hospital (2005-2018). The type of antibiotic administered to the mothers for GBS prophylaxis (beta-lactam prophylaxis defined as penicillin-class drug or cefazolin; alternative prophylaxis defined as vancomycin or clindamycin) was compared between those with a penicillin allergy documented in their medical record versus those who did not. Neonatal outcomes included number of postnatal blood draws, antibiotic administration, neonatal intensive care unit (NICU) admission, bacteremia, and hospital length of stay and were compared between groups. Bivariable and multivariable analyses were performed. RESULTS: Of 11,334 mother-infant pairs, 1170 (10.3%) mothers had a penicillin allergy documented in their medical record. Of them, 49 (4.2%) received a penicillin, 259 (22.1%) received cefazolin, 449 (38.4%) received clindamycin, and 413 (35.3%) received vancomycin. Patients with a reported penicillin allergy were significantly more likely to receive alternative GBS prophylaxis compared to those without penicillin allergy (73.7% vs. 0.2%, p < 0.01). Neonates of patients who received alternative GBS prophylaxis were significantly more likely to undergo a postnatal lab draw compared to neonates of patients who received beta-lactam antibiotics (20.8% vs. 17.3%, OR 1.25 (95% CI 1.08-1.46)). This significant association persisted after adjusting for potential confounders (aOR 1.23, 95% CI 1.06-1.43). There were no other significant differences seen in other newborn outcomes. CONCLUSION: Pregnant individuals who report a penicillin allergy were more likely to receive alternative antibiotics for GBS prophylaxis compared to those without a penicillin allergy. This was associated with an increased frequency of postnatal blood draws among neonates of mothers with a reported penicillin allergy. Administration of alternative intrapartum antibiotic prophylaxis with vancomycin or clindamycin is common in individuals with self-reported penicillin allergy, and maternal alternative antibiotic administration may impact neonatal care, particularly via increased lab draws.

Retrospective Evaluation of the Association of Oxacillin MIC on Acute Treatment Outcomes with Cefazolin and Antistaphylococcal Penicillins in Methicillin-Susceptible Staphylococcus aureus Bacteremia.

Antistaphylococcal penicillins (ASP) and cefazolin are first-line treatment of methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia. Borderline oxacillin resistance (i.e., oxacillin MICs 1-8 µg/mL) is observed in strains hyperproducing beta-lactamases. This mechanism is also behind the proposed inoculum effect. Minimal data exists on the comparative efficacy of cefazolin or ASP in qualitatively susceptible strains that demonstrate MICs of oxacillin of 1 to 2 µg/mL compared to strains with MIC of oxacillin < 1 µg/mL. We performed a retrospective cohort study of acute treatment outcomes in adult patients with community-acquired MSSA bacteremia treated with cefazolin or ASP, stratified by oxacillin MIC. The primary outcome was a composite of all-cause mortality during the index inpatient admission, failure to clear blood cultures within 72 h after initiating definitive therapy, and change in therapy due to perceived lack of efficacy. A total of 402 patients were included in this study, including 226 isolates with an oxacillin MIC ≥ 1 µg/mL and 176 isolates with an MIC < 1 µg/mL. There were no differences in the rate of the primary outcome occurrence between patients with an oxacillin MIC ≥ 1 µg/mL and an MIC < 1 µg/mL (16.4% versus 15.9%, P = 0.90). There was no difference in the primary outcome between high versus low oxacillin MIC groups among those who received ASP (22.9% versus 24.1%, P = 0.86) or cefazolin (10.3% versus 11.9%, P = 0.86). In our cohort of patients with MSSA bacteremia, oxacillin MIC (i.e., ≥ 1 versus < 1 µg/mL) was not associated with acute treatment outcomes, regardless of the beta-lactam selected as definitive therapy.

Pharmacist-led improvement in perioperative antibiotic selection for patients with a penicillin allergy label.

PURPOSE: Surgical patients with a penicillin allergy label (PAL) are less likely to receive ß-lactams for surgical site infection (SSI) prophylaxis and more likely to receive second-line antibiotics, which may increase the risk of SSI, drug toxicities, and associated costs. We assessed the impact of implementing a pharmacist-led quality improvement project to increase the use of cefazolin as a first-line agent in this population. SUMMARY: After implementation of a pilot project in December 2021, all patients with a PAL and orders for preoperative antibiotics were risk stratified into high- or low-risk categories by a pharmacist. For the low-risk group, cefazolin was recommended. For the high-risk group, cefazolin was avoided and a second-line agent was administered. Our analysis compared 422 preintervention patients (August 15 to November 15, 2021) to 492 postintervention patients (December 15 to March 15, 2022). During the postintervention period, ß-lactam usage increased (from 12.6% to 37.8%, P < 0.001), while usage of vancomycin (45.5% vs 29.5%, P < 0.001) and other second-line antibiotics (87.4% vs 62.2%, P < 0.001) declined. There were no adverse reactions reported in the preintervention cohort, with 2 potential adverse reactions reported after the intervention (0% vs 0.4%, P = 0.190). Medication costs based on claims data were 50% to 80% lower for patients receiving cefazolin. CONCLUSION: In our cohort, a pharmacy-led antibiotic selection algorithm for patients with a PAL receiving perioperative antimicrobial prophylaxis resulted in increased use of ß-lactam antibiotics, decreased use of second-line antibiotics, and decreased costs without a significant change in the incidence of adverse reactions.

Pharmacist adjustment of preoperative antibiotic orders to the preferred preoperative antibiotic cefazolin for patients with penicillin allergy labeling.

PURPOSE: Emerging literature has detailed the safe use of cefazolin in patients with immunoglobulin E-mediated penicillin allergy labeling (PAL) such as hives and anaphylaxis. The purpose of this article is to detail efforts led by an antimicrobial stewardship pharmacist working with an interdisciplinary team to optimize preoperative antimicrobials in patients with PAL. METHODS: A pharmacist-led, interdisciplinary collaborative practice agreement (CPA) was activated in January 2020 to permit pharmacists to independently optimize preoperative antibiotics to the preferred cefazolin in patients with PAL if nonsevere or severe reactions had been reported. A patient registry was established covering the timeframe between January 8, 2020, and January 6, 2022. Reaction during surgery was assessed via 2-provider documentation, which included surgeon and anesthesiology staff documentation of any complications during the procedure related to a suspected allergic safety event. Utilization of cefazolin, clindamycin, and vancomycin for preoperative prophylaxis was monitored before and after implementation of the CPA. RESULTS: During the stated timeframe, 10,182 procedures and/or surgeries were completed on 1,572 (15.4%) patients with PAL and 659 (41.9%) patients previously reporting at least one reaction categorized as a severe reaction, which was hives for 71.2% of these patients. Of the 659 patients with PAL reporting a severe reaction, 356 received a preoperative cephalosporin (cefazolin, 98.8%; ceftriaxone, 1.2%) and tolerated it without a reported safety event, including 52 patients with PAL previously reporting anaphylaxis. An increase in preferred preoperative antimicrobial prophylaxis utilization was noted (cefazolin: 86% to 96.3%, P < 0.001; 2019 to 2021) with reductions noted in the use of nonpreferred preoperative antibiotics (clindamycin: 2.1% to 0.2%, P < 0.001; vancomycin: 3.2% to 0.4%, P < 0.001; 2019 to 2021). CONCLUSION: A pharmacist-led, interdisciplinary CPA increased preferred preoperative antimicrobial use in patients with PAL reporting severe allergic reactions, including hives and anaphylaxis, without reported safety events.

Cefazolin in the treatment of central nervous system infections: A narrative review and recommendation.

Infections of the central nervous system (CNS) are complex to treat and associated with significant morbidity and mortality. Historically, antistaphylococcal penicillins such as nafcillin were recommended for the treatment of methicillin-susceptible staphylococcal CNS infections. However, the use of antistaphylococcal penicillins presents challenges, such as frequent dosing administration and adverse events with protracted use. This narrative reviews available clinical and pharmacokinetic/pharmacodynamic (PK/PD) data for cefazolin in CNS infections and produces a recommendation for use. Based on the limited available evidence analyzed, dose optimized cefazolin is likely a safe and effective alternative to antistaphylococcal penicillins for a variety of CNS infections due to methicillin-susceptible Staphylococcus aureus. Given the site of infection and wide therapeutic index of cefazolin, practitioners may consider dosing cefazolin regimens of 2 g IV every 6 h or a continuous infusion of 8-10 g daily instead of 2 g IV every 8 h to optimize PK/PD properties.

A case series of perioperative anaphylaxis to cefazolin during kidney transplant and review of literature.

BACKGROUND: Intraoperative anaphylaxis is a life threatening and multiorgan system hypersensitivity reaction that frequently leads to cessation of operations. Despite the incidence of Cefazolin allergy being on the rise, the cases of anaphylaxis to Cefazolin during surgeries and its management are seldom reported. CASE PRESENTATION: We present two patients with no known beta-lactam allergy and end stage kidney disease who received perioperative intravenous Cefazolin for planned deceased kidney transplant surgery at our academic medical center. Both patients developed anaphylaxes approximately three minutes following the administration of the antibiotic and experienced severe, refractory hypotension that required the use of vasopressors. The severity of the anaphylactic reactions resulted in the cessation of the transplant operation and multiple days of intensive care unit admission. CONCLUSION: Peri-or intraoperative anaphylaxis to Cefazolin is on the rise and its consequences in transplant candidates are even more dire given the pre-existing end organ failure, financial burden for health care system, potential loss of donor organs, and emotional burden for recipients and their families. These are the first two cases of reported Cefazolin-induced anaphylaxis that actually resulted in aborting the kidney transplant operation. In addition, cases of previously reported Type 1 hypersensitivity to Cefazolin as prophylaxis for operations were reviewed and the allergy workups were discussed.

Antibiotic prophylaxis for percutaneous renal biopsy: study protocol for a prospective randomized trial.

BACKGROUND: The major complication of renal biopsy is bleeding. Infection is an extremely rare complication of percutaneous renal biopsy, providing sterile techniques are used and bowel perforation does not occur. However, the questionnaire included in the Kidney Biopsy Guidebook 2020 in Japan reported that antibiotic prophylaxis was administered to patients undergoing percutaneous renal biopsy at 61% of 170 adult institutions and 57% of 54 pediatric institutions. The objective of this study is to show the non-inferiority of not administering antibiotic prophylaxis for percutaneous renal biopsy. METHODS: Patients aged ≥15 years who are scheduled to undergo percutaneous renal biopsy are eligible for inclusion in the study. Three hundred and sixty-four patients will be recruited at 6 hospitals. The patients will be randomly assigned at a 1:1 ratio to receive either a single dose of intravenous cefazolin (1 g) or no antibiotic prophylaxis. The primary outcome is the number of patients that exhibit positive urine cultures (>105 colony-forming units/ml) 3 or 4 days after the renal biopsy, or at which point the patients are diagnosed with pyelonephritis until 3 or 4 days after the renal biopsy. The secondary outcomes are the number of patients who are diagnosed with pyelonephritis within 30 days after the renal biopsy, the number of patients who are diagnosed with puncture site infections within 30 days after the renal biopsy, the number of patients who are diagnosed with an infection other than pyelonephritis or a puncture site infection within 30 days after the renal biopsy, and the number of patients who experience cefazolin-induced side effects. DISCUSSION: This randomized controlled trial aims to show the non-inferiority of not administering antibiotic prophylaxis for percutaneous renal biopsy. If this study shows that antibiotic prophylaxis is not needed, it would help to ensure patient safety and prevent the development of antibiotic-resistant bacteria. TRIAL REGISTRATION: UMIN Clinical Trials Registry (UMIN-CTR) UMIN000042378 . Registered on 7 Nov 2020.

Ceftriaxone versus cefazolin for the treatment of methicillin-susceptible Staphylococcus aureus bacteraemia.

Few studies have evaluated the use of ceftriaxone (CRO) in the treatment of methicillin-susceptible Staphylococcus aureus (MSSA) infections. The purpose of this study was to compare the safety and efficacy of CRO versus cefazolin (CZO) for patients with MSSA bacteraemia. This was a multicentre, single health-system, retrospective study. Adult inpatients were included if they had a primary episode of MSSA bacteraemia and received CRO or CZO as definitive therapy. The primary endpoint was clinical cure at 28 days or at discharge, whichever came first. Secondary endpoints included treatment failure at 90 days, time to treatment failure, re-admission due to recurrent MSSA bacteraemia, duration of bacteraemia, discontinuation of treatment due to adverse drug events, and Clostridioides difficile infection. A total of 248 patients were included, of which 87 (35.1%) received CRO and 161 (64.9%) received CZO. There was no difference in the primary outcome of clinical cure at 28 days or at discharge between the CRO and CZO groups [75 (86.2%) vs. 145 (90.1%); P = 0.359], even after adjusting for Charlson comorbidity index and Pitt bacteremia score (adjusted OR = 1.35, 95% CI 0.58-3.12; P = 0.49). There were no differences in time to clinical cure, treatment failure at 90 days or safety events between the two groups. In conclusion, our findings suggest no clinical difference between CRO and CZO for the definitive treatment of MSSA bacteraemia. Further prospective studies are needed to confirm these findings.