To the Editor-The COVID-19 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a public health problem of historic dimensions. However, this pandemic is occurring in the setting of an antimicrobial resistance crisis that is increasing at an alarming pace worldwide. Of concern, countries with a particularly high incidence of COVID-19 also have significant rates of infection caused by multidrug-resistant bacteria. During the 2009 influenza pandemic, coinfection with bacteria was identified as a prognostic factor for the worse outcomes. 1 This finding has led to empirical antibiotic therapy being recommended for patients with suspected influenza pneumonia, 2 and it has probably been a major reason underpinning the initial World Health Organization's recommendation to use empirical antibiotics in cases of COVID-19 pneumonia. 3 Although this guideline advocated for early antimicrobial de-escalation, a couple of factors may have hindered this practice. First, processing microbiological samples in saturated emergency rooms and overloaded laboratories is difficult. Second, no evidence-based antiviral treatment for COVID-19 has been developed in the setting of a highly stressful situation. Together, these factors may have prompted clinicians to prescribe broad-spectrum antimicrobials more often than they may otherwise have. Therefore, antimicrobial stewardship approaches urgently need to be reinforced during the COVID-19 pandemic. 4 To date, however, no study has evaluated the impact of the COVID-19 pandemic on antibiotic consumption. We conducted a before-and-after cross-sectional study comparing data in 2019 (before the COVID-19 pandemic began) and 2020 (COVID-19) for the periods from January 1 to April 30. Bellvitge University Hospital is a 700-bed hospital that serves as a public referral center of 1 million inhabitants in Catalonia, the second worst pandemic-affected area in Spain. 5 As of April 30, 2020, this hospital had had >1,293 hospital admissions for COVID-19, with a 317% increase in critical care bed use. In this study, we calculated the defined daily dose per 100 patient days, as described elsewhere, and based on the dispensing data of our electronic prescribing system. Medians for continuous variables were compared using the Wilcoxon log-rank test.

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The combined CYP3A4 and CYP3A5 genotype of renal transplant recipients has a major influence on the Tac dose required to reach the target exposure.