High Diagnostic Accuracy of Nitrite Test Paired with Urine Sediment can Reduce Unnecessary Antibiotic Therapy
Sven A. Ferry1, *, Stig E. Holm2, B. Magnus Ferry3, Tor J. Monsen1
1 Department of Clinical Microbiology, Bacteriology, Umea University, Umea, Sweden
2 Department of Medical Microbiology and Immunology, University of Gothenburg, Gothenburg, Sweden
3 Department of Education, Umea University, Umea, Sweden
Urinary tract infections (UTIs) are common bacterial infections dominated by lower UTI in
women (LUTIW). Symptoms only are insufficient for diagnosis and accordingly, near patient diagnostic tests confidently
confirming significant bacteriuria are desirable. The nitrite test (NIT) has low sensitivity, while bacterial and leukocyte
counts disjunctively paired in urine sediment microscopy (SED) have high sensitivity. Similar symptomatic cure rates are
found post antibiotic vs. placebo therapy in patients with negative cultures. Consequently, prescription on symptoms only
implies unnecessary antibiotic therapy.
to evaluate the diagnostic outcomes of NIT, SED and NIT disjunctively paired with SED (NIT+SED) vs. urine
culture, with special focus on bladder incubation time (BIT), and to assess if NIT+SED can reduce unnecessary antibiotic
A diagnostic, primary care, multicentre study including 1070 women with symptoms suggestive of lower UTI.
Significant bacteriuria was found in 77%. The BIT highly influenced the diagnostic outcomes and the optimal
duration was 4h with sensitivity of 66, 90 and 95% for NIT, SED and NIT+SED, respectively. SED performed only in
NIT negative specimens could reduce unnecessary antibiotics by 10% vs. prescription on symptoms only. The number
needed to test with SED to reduce one unnecessary antibiotic course was five patients at BIT ≥4h and six patients at ≤3h
The BIT highly influences the diagnostic outcomes with the highest accuracy of NIT+SED. Diagnosis of
LUTIW with NIT+SED can reduce unnecessary antibiotic therapy and subsequently decrease antimicrobial resistance.
The Swedish Medical Product Agency 1995 03 01:151:01783/94.
Keywords: Antibiotic resistance, bacteria, bladder incubation time, diagnosis, dipstick test, leukocytes, primary care, urinary
open-access license: This is an open access article licensed under the terms of the (https://creativecommons.org/licenses/by/4.0/legalcode), which permits unrestricted, noncommercial
use, distribution and reproduction in any medium, provided the work is properly cited.
* Address correspondence to this author at the Department of Clinical
Microbiology, University Hospital of Umea, SE-90185 Umea, Sweden;
Tel: +46705782019; Fax: + 4690131802;