The use of initial dosing of gentamicin in the management of pyelonephritis/urosepsis: A retrospective study

OBJECTIVE: The primary objective was to determine if initial empirical intravenous dosing of gentamicin improved patient's outcomes in pyelonephritis/urosepsis compared with alternative IV antibiotic management. DESIGN: Retrospective cross-sectional descriptive study. SETTING: Public TertiaryTeaching Hospital serving adults in an urban centre. PARTICIPANTS: All adult patient records with a recorded diagnosis of any of pyelonephritis/urosepsis, urinary tract infection, UTI, complicated urinary tract infection, bacteriuria, symptomatic bacteriuria and asymptomatic bacteriuria from 2(nd) February 2012 to 10(th) May 2014 were reviewed. Only patients treated with an empirical regimen of one or more IV antibiotics were included in the study. MAIN OUTCOMES: The primary outcomes were: duration of IV antibiotic treatment, time to resolution of symptoms and length of hospital stay (LOS). Secondary end points were: compliance with Therapeutic Guidelines: Antibiotic (electronic version) (eTG) for severe pyelonephritis/urosepsis and appropriateness of gentamicin use. DATA ANALYSIS: Univariate and multivariable associations between baseline and demographic variables and the main outcomes were performed using Chi-square tests and a General Linear Model using the SAS version 9.2 software. RESULTS: Of 295 patients reviewed 152 were prescribed one or more IV antibiotics and included in the study. Approximately half of the patients (n = 73, 48%) were prescribed IV piperacillin/tazobactam (Tazocin), while gentamicin was prescribed for 66 patients (43.4%). Of the 152 patients evaluated, 49 (32%) were given gentamicin first. Multivariable regression analysis showed that duration of IV treatment was shorter for those aged over 70 (40.2 hours vs 85.5 hours for those aged up to 70; p = 0.0074), and those who received gentamicin as first line treatment (41.3 hours vs 89.8 hours for those not receiving any gentamicin; p = 0.0312). After adjustment for age and gentamicin administration, there appeared to be no significant difference in duration of IV treatment for any other independent variables. No significant associations between the independent variables (gentamicin, age, gender, comorbidities, and eTG compliance) and either time to resolution of symptoms (median: 68 hours) or hospital LOS (median: 5 days) were observed. CONCLUSIONS: Neither time to resolution of abnormal symptoms nor length of stay were significantly influenced by an initial dose of gentamicin when the data were subjected to multivariable analysis. The age of the patient and pattern of gentamicin treatment were the dominant factors associated with duration of IV antibiotics. Piperacillin/tazobactam is not recommended in treatment guidelines for pyelonephritis/urosepsis but was the most commonly prescribed IV antibiotic. This requires review by the appropriate hospital clinicians.