Relevance of blood cultures in acute pyelonephritis in a single-center retrospective study

Abstract

Pyelonephritides are frequently encountered diagnosis in Emergency Departments. Urinalyses have a central place in the management of this situation but the usefulness of blood cultures is not clear. We conducted a single-center retrospective study of 24 months to study the microbiological relevance of blood cultures in pyelonephritis. We included patients with blood cultures (BC) and urine cultures (UC) drawn at the same time, if they were not exposed to antibiotics prior to these tests. Of our 264 patients, 39 (15 %) had no bacteriological documentation. There were 83 (31 %) bacteremic patients. Seven patients had contaminated or sterile UC with positive BC. Four patients had positive UC and BC with the latter allowing identification of a pathogen absent from the UC (n = 1) or identifying the main pathogen in three cases. A total of 11 patients theoretically benefited from BC representing 4.2 % of our population. Excluding one patient who was known to be infected with multi-drug resistant bacteria, all empirical antibiotics regimens were effective against the identified pathogens. We did not reveal any significant therapeutic impact of blood cultures in the management of pyelonephritis, when BC and UC are performed before any antimicrobials treatment.

Is it Always Necessary to Take Blood Cultures before Starting Antibiotics in the Emergency Department? A Review of Usefulness of Blood Cultures in Community-Acquired Pneumonia, Cellulitis, Urinary Tract Infection and Pyelonephritis

“…This is similar to Kim, et al in 2017 which shows a true positive rate of 42.7% in patients with communityacquired acute pyelonephritis of which 15.8% involved a change in antibiotic regimen [34]. Testing positive for bacteraemia was also a significant predictor of hospital mortality and hence, blood cultures were clinically useful for diagnosis of community-acquired acute pyelonephritis [33,35,36].…”

“…The author concluded that only 2% of all cultures returned useful information for changing empiric management; while there was higher yield of blood cultures in the complicated group, the results rarely changed empirical coverage for complicated patient presents with fever or other signs of a serious infection to check for bacteraemia or other possible differentials [31][32][33][34]. However, up to 30% of women with acute pyelonephritis may have secondary bacteraemia, and identification of the organism by blood culture can be helpful in some cases where antibiotics are started in advance of the urine culture [29,32,35,36].…”

“…However, another study done in 2015 for acute pyelonephritis showed that less than 2% of all pyelonephritis treated at the ED during the study period benefitted from the blood cultures, indicating no significant therapeutic impact of blood cultures before any antibiotic exposure [38]. It was mentioned that blood cultures added little information to urine cultures, which played a bigger role in pyelonephritis [35]. Gomi, et al in 2011 showed no supporting evidence on whether routine blood cultures improved outcomes in the management of pyelonephritis in pregnant patients.…”

Risk Factors for Bacteremia and Its Clinical Impact on Complicated Community-Acquired Urinary Tract Infection

“…Bacteremia has been reported in 20% to 31% of cases of acute pyelonephritis [ 10 , 13 , 14 ] and in 38% to 69% severe sepsis or septic shock [ 15 ]. In addition, bacteremia was the only way to establish etiology in 7% to 11.6% of complicated UTI when urine cultures were negative or contaminated [ 16 ].…”

Clinical effect of discordance in empirical treatment of cases with urinary tract infection accompanied by bacteremia

“…[1][2][3] Bacterial agent is most often Escherichia coli, while Gram-negative cocci, enterococci, and Staphylococcus saprophyticus may also cause this infection. [4] In recent studies, extended-spectrum beta-lactamase (ESBL) producing strains have been detected in E.coli isolates at a higher frequency, both in the world, and in our country.…”