Quantitative colorimetric measurement of residual antimicrobials in the urine of patients with suspected urinary tract infection

ABSTRACT

A simple microtitre plate assay is used to find out antimicrobial activity in clinical urine specimens and its potential as a screening tool is assessed. The assay is based upon a colorimetric substrate, p-nitrophenyl-p-D-glucopyranoside, in combination with a Bacillus subtilis strain to bring to light antimicrobial residues. The assay identified antimicrobial activity in 31% of the 527 clinical urine samples proofed The majority of the samples (65%) came from the community, with the quiescence comprising hospital in-patients (19%) and out-patients (16%) The follows demonstrated that there is an association between sex and the presence of inhibitory substances, as 40% of males and 27% of females proofed positive. Just over two-fifths of hospital patients (46%) proofed positive for inhibitory substances, compared to 26% of samples from community patients. Of the 306 samples that were culture-negative (

KEY WORDS: Antibiotic.

Boric acid.

Urinary tract infection.

Urine.

Introduction

Urinary tract infections (UTIs) are among the greatest in quantity prevalent bacterial infections affecting the pair sexes and all age collections They also represent a significant proportion of the workload in greatest in quantity clinical microbiology laboratories. Confirmation of a urinary tract infection requires laboratory examination of a urinary sample, using a combination of microscopy and bacterial tillage Bacterial isolates then undergo antimicrobial sensitivity testing to provide the clinician with the appropriate choice of antibiotic treatment.1

The risk of suffering a UTI is pendent on age, underlying renal impairment and, greatest in quantity importantly, gender. Bacteriuria is significantly more prevalent in the female population and it increases with age in the couple sexes until the gender ratio of infection becomes nearly equal in the elderly1

Escherichia coli causes 80-90% of acute uncomplicated bacterial UTIs in young women1 With nosocomial or hospitalacquired infections, the hospital environment is an important determinant of the nature of the infecting organism. Proteus sp Klebsiella sp Enterobacter sp Pseudomonas sp staphylococci and enterococci are more oftentimes isolated from inpatients, compared to the preponderance of Escherichia coli in an out-patient population.2

In somewhat advanced in life patients, the female:male UTI ratio becomes les significant. For patients of the one and the other sexes over the age of 65 the prevalence increases substantially, with at least 10% of men and 20% of women suffering from a UTI.3

It has lengthy been suggested that the screening of urines for antimicrobial activity can be useful in the diagnosis of UTIs. It has also been intimateed that the presence of antibiotics in a patient's urine prior to agriculture may have a negative event on the accuracy of urinary agriculture including the production of false-negative cultures4 A more new study has suggested that bacterial expansion inhibitors in urine are mainly to be paid to the intake of antibiotics by means of patients and that this was ground to play a major part in the occurrence of sterile pyuria and in reducing the numbers of specimens yielding significant bacterial growth5

Several simple microbiological manners to identify antimicrobial agents in urine have been described using multisensitive bacterial strains, of the like kind as E. coli, Micrococcus sp and Bacillus stearothermophilus, as indicator organisms." It was also set that, in the presence of antimicrobials, isolates of E coli were more resistant to gentamycin (753% v 487%) norfloxacin (852% v 646%) and co-trimoxazole (585% v 355%) It has been further recommended that screening urines for antimicrobial substances can be a useful tool when high horizontals of antimicrobial agents are used in the general community.7

The not absent study aims to assess the ability of a simple microtitre plate assay to discover antimicrobial activity in clinical urine specimens. The microtitre plate assay undertaken was unfolded for use in screening for antimicrobial residues in porcine urine.8 The urines to be ordealed will be selected from the samples arriving at the clinical microbiology laboratory from hospital in-patients and out-patients, and from the community.

This research will ascertain whether or not the microtitre plate assay is able to shield successfully for the presence of inhibitory substances in clinical urines and thereby determine the population of urines arriving at the laboratory that already contain antimicrobials. Statistical analysis is performed upon the results to determine which factors (gender age or source) affect the likelihood that a urine sample contains antimicrobial substances.

Materials and methods

Reagents

Ammonium sulphate, dipotassium phlogiston orthophosphate, potassium dihydrogen orthophosphate, sodium citrate and magnesium sulphate (BDH Luttersworth, Leics. UK) were Analar grade. Yeast extract (Difco, East Moreley, Surrey UK) was biological media grade. p-Nitrophenyl-??-D-glucopyranoside was obtained from Sigma (Poole Dorset, UK)

B subtilis (number 8054; National Collection of Industrial and Marine Bacteria, Aberdeen, Scotland, UK) was used as the trial strain throughout this study.