The prevalence of resistant Gram-negative bacteraemia among hospitalized patients in Tucson, Arizona over a 12-month period; A retrospective single centre study.

INTRODUCTION: The objectives of this retrospective review were to: (a) determine the prevalence of resistant Gram-negative bacteraemia among hospitalized patients; (b) evaluate antibiotic use; (c) determine the time taken for Gram staining to final species identification.

METHODS: For this retrospective study, information was extracted from patients' electronic medical records. Eligible patients had been admitted to a 300-bed tertiary care hospital in Tucson, Arizona from October 2015 to October 2016, were over 18 years of age and had a positive blood culture for Gram-negative bacteraemia.

RESULTS: In total, 84 patients with Gram-negative bacteraemia were identified; urinary tract infection was the most common source of infection (71%). ESBL-producing microorganisms were isolated from five (6%) patients and no MDR pathogens were identified. The, median time to Gram stain was 20.5 hours and the median time to final identification was 54.5 hours. Delayed de-escalation of broad-spectrum antibiotics (i.e., >24 hours after final culture) occurred in 25% patients with a median length of hospital stay of 118 hours (range: 56-552 hours) compared with a median length of hospital stay of 89 hours (range: 5-334 hours) in the early de-escalation group.

CONCLUSION: The prevalence of bacteraemia due to resistant Gram-negative microorganisms is low (6%) in this institution. However, there may be room for improvement in the antimicrobial stewardship program with regard to rapid diagnostic testing.