Article
Efficacy of Urine Dipstick Test in Diagnosing Urinary
Tract Infection and Detection of the blaCTX-M Gene among ESBL-Producing Escherichia coli
Rubina Gurung1, Sanjib Adhikari1, Nabaraj Adhikari1,
Sanjeep Sapkota2, Jid Chani Rana3, Binod Dhungel1,
Upendra Thapa Shrestha1, Megha Raj Banjara1, Prakash
Ghimire1 and Komal Raj Rijal1*
1Central Department of Microbiology, Tribhuvan University,
Kirtipur 44600, Kathmandu, Nepal;
2Department of Microbiology, Birendra Multiple Campus,
Tribhuvan University, Bharatpur 44200, Chitwan, Nepal;
3Department of Microbiology, Bharatpur Hospital, Bharatpur
44200, Chitwan, Nepal;
* Correspondence: rijalkomal@gmail.com or
komal.rijal@cdmi.tu.edu.np
ABSTRACT
A urine dipstick test used for prompt diagnosis of
urinary tract infection (UTI) is a rapid and cost-effective method. The main
objective of this study was to compare the efficacy of the urine dipstick test
with culture methods in screening for UTIs along with the detection of the blaCTX-M gene in extended spectrum-lactamase (ESBL)-producing Escherichia coli.
A total of 217 mid-stream urine samples were collected from UTI-suspected
patients attending Bharatpur Hospital, Chitwan, and tested by dipstick test
strip (COMBI-10SL, Germany) prior to the culture. E. coli isolates were identified by standard microbiological
procedures and subjected to antimicrobial susceptibility testing by Kirby Bauer
disc diffusion method following CLSI guideline. Primary screening of
ESBLproducing E. coli isolates was
conducted using ceftriaxone, cefotaxime and ceftazidime discs and phenotypically
confirmed by combined disk diffusion test. Plasmid DNA of ESBL-producing
strains was extracted by phenol-chloroform method and subjected to PCR for
detection of the blaCTX-M gene. Out of
217 urine samples, 48 (22.12%) showed significant bacteriuria. Among 46
(21.20%) Gram negative bacteria recovered, the predominant one was E. coli 37 (77.08%) of which 33 (89.19%) were multidrug resistant
(MDR). E. coli isolates showed a
higher degree of resistance towards cefazolin (62.16%) while 81.08% of the
isolates were sensitive towards amikacin followed by nitrofurantoin (70.27%).
Among 14 (37.84%) phenotypically confirmed ESBL isolates, only eight (21.62%)
isolates carried the blaCTX-M gene.
Sensitivity, specificity, positive predictive value (PPV) and negative predictive
value (NPV) of urine dipstick test were 43.75%, 77.51%, 35.59% and 82.91%,
respectively. Besides, the use of dipstick test strip for screening UTI was
associated with many false positive and negative results as compared to the
gold standard culture method. Hence, dipstick nitrite test alone should not be
used as sole method for screening UTIs.
Keywords:
Escherichia coli; ESBL; sensitivity; specificity; PPV; NPV; blaCTX-M
Citation: Gurung,
R.; Adhikari, S.; Adhikari, N.; Sapkota, S.; Rana, J.C.; Dhungel, B.; Thapa
Shrestha, U.; Banjara, M.R.; Ghimire, P.; Rijal, K.R. Efficacy of Urine
Dipstick Test in Diagnosing Urinary Tract Infection and Detection of the blaCTX-M
Gene among ESBL-Producing Escherichia coli. Diseases 2021, 9, 59. https://doi.org/10.3390/diseases9030059
Academic Editor: St Patrick Reid
Received: 26 June 2021
Accepted: 26 August 2021
Published: 27 August 2021
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2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open-access
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