1989. Evaluation of Laser Light Scattering Technology in Rapid Diagnosis of Urinary Tract Infections in Children
Session: Poster Abstract Session: Diagnostics: Bacteria and Mycobacteria
Saturday, October 6, 2018
Room: S Poster Hall
Background: Urinalysis (UA) has been routinely used as a screening tool prior to microbial culture set-up in many labs. BacterioScan 216Dx instrument utilizes laser light scattering technology to detect bacterial growth in urine and results are available in 3 hrs. The aim of this study was to compare the performance of 216 DX and UA against culture as gold standard.

Methods: Clean-catch, unpreserved, either UA positive (leukocyte esterase > trace, or nitrite positive or white blood cells >5/hpf) or UA negative samples from children aged ≤18 years were tested by 216Dx within 24 hours of sample collection. ‘Likely positive’ samples by 216Dx were tested by MALDI-TOF for direct bacterial identification. Sensitivity and specificity of 216Dx and UA was determined against urine culture.

Results: Total of 205 urine samples were included in this study, of which 48.0% (98/205) and 52.0% (107/205) were UA positive and negative, respectively. 77.0% of samples were collected from female and median age was 108 months. Overall sensitivity, specificity, positive and negative predictive value (PPV and NPV) of 216Dx and UA are shown in table below. Of 27 true positive (TP) samples by 216Dx, 77.0% (21/27) were successfully identified by MALDI-TOF. There were a total of 96 samples identified as contamination/normal flora by culture. Among these, 63 samples (65.0%) were detected as true negative (TN) by 216Dx vs 50 samples (53.1%) as TN by UA. Two false negative (FN) samples by 216Dx and one FN by UA were K. oxytoca, S. epidermidis (both >100 K cfu/ml) and E. coli (>100 K cfu/ml), respectively.

Conclusion: Although sensitivity of both 216Dx and UA is comparable, specificity of 216Dx was higher than UA. Also, 216Dx showed better performance in detecting urine contamination, thus reducing laboratory reagent and labor cost. Faster turn-around-time of 216Dx coupled with rapid identification of uropathogen by MALDI-TOF has the potential to reduce unnecessary antibiotic use, improve patient-management and reduce overall health-care related cost.

Assay

TP

FP

TN

FN

%Sensitivity

(95% CI)

%Specificity

(95% CI)

%PPV

(95% CI)

%NPV

(95% CI)

216Dx

27

36

140

2

93.1

(75.7-98.8)

79.5

(72.6.0-85.1)

42.8

(30.6-55.9)

98.6

(94.4-99.7)

UA

28

70

106

1

96.5

(80.3-99.8)

60.2

(52.5-67.4)

28.5

(20.1-38.7)

99.0

(94.1-99.9)

Ferdaus Hassan, PhD1, Heather Bushnell, BS2, Connie Taggart, MLS (ASCP)3, Caitlin Gibbs, MLS (ASCP)4, Steven Hiraki, MLS (ASCP)4, Ashley Formanek, MLS (ASCP)4, Megan Gripka, MLS (ASCP) SM5 and Rangaraj Selvarangan, PhD1, (1)Children's Mercy, Kansas City, MO, (2)Children's Mercy Hospitals and Clinics, Kansas City, MO, (3)Clinical Microbiology, Children's Mercy Hospitals, Kansas City, MO, (4)Children's Mercy Hospitals, Kansas City, MO, (5)Microbiology, Children's Mercy Hospital-Kansas City, Kansas City, MO

Disclosures:

F. Hassan, None

H. Bushnell, None

C. Taggart, None

C. Gibbs, None

S. Hiraki, None

A. Formanek, None

M. Gripka, None

R. Selvarangan, None

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