Abstract
Background The occurrence of urinary tract infection in presence of urolithiasis is frequently noted; however, microbial agents of urolithiasis and their antimicrobial susceptibility patterns remain underinvestigated. This study aimed to identify the microorganisms isolated from urine and stone matrices to determine their antimicrobial susceptibility, to find the association between the pathogens of urine and stone matrices, and to perform the biochemical analysis of stones. Methods A total of 88 cases of urolithiasis admitted for elective stone removal at Department of surgery, B.P. Koirala Institute of Health Sciences (BPKIHS), were enrolled. Preoperative urine culture and postoperative stone culture were performed. Isolation, identification, and AST were done by the standard microbiological technique. Further qualitative biochemical analysis of stones was also attempted. Result Among 88 stone formers recruited, culture of urine, whole stone, and nidus yielded the growth of bacteria 44, 32, and 30, respectively. Bacteria isolated from urine culture correlated with those from stone matrices with a sensitivity of 90%, specificity of 79.69%, PPV of 63.64%, and NPV of 95.45%. Escherichia coli (46.7%) was the most common bacteria followed by Klebsiella pneumoniae (16.7%) and Proteus mirabilis (13.3%) from urine and stone cultures. Almost all the uropathogens isolated were susceptible to commonly used antibiotics. Calcium oxalate (84.1%) was common biochemical constituent found in stone formers followed by calcium oxalate + phosphate (8%). Conclusions The association of microorganism isolated from urine and nidus culture was significant that can predict the source of infective stone; however, in some cases, microorganisms and the antimicrobial susceptibility pattern from urine and nidus were different. This study emphasizes the use of appropriate antimicrobial agents to prevent the regrowth of residual stones and minimize the risk of infectious complications after surgical removal of stones.
Highlights
Urolithiasis is one of the frequently encountered urological disorders, common throughout the world, and is highly prevalent in Nepal [1].e association between urolithiasis and urinary tract infections (UTIs) is well known and is frequently detected. eir interrelationship can be defined in two ways: urolithiasis following UTIs, i.e., “infection-induced stones” or urinary stone with subsequent UTIs as its complications [2]
E association between urolithiasis and urinary tract infections (UTIs) is well known and is frequently detected. eir interrelationship can be defined in two ways: urolithiasis following UTIs, i.e., “infection-induced stones” or urinary stone with subsequent UTIs as its complications [2]
International Journal of Microbiology ammonium phosphate, whereas urea-splitting bacteria like Proteus spp., Staphylococcus aureus, Klebsiella spp., Providencia spp., and Ureaplasma urealyticum are commonly responsible for struvite stone. e antimicrobial agents could not invade, where these bacteria lie within the interspace of stones in urinary tract. us, the outcome is progressive expansion of stones because of persistent infection over a period of weeks or months [2, 4]
Summary
Urolithiasis is one of the frequently encountered urological disorders, common throughout the world, and is highly prevalent in Nepal [1]. E antimicrobial agents could not invade, where these bacteria lie within the interspace of stones in urinary tract. Us, this study was aimed to identify the type of bacteriology of urine and stone matrices, determine their antimicrobial sensitivity pattern, and find the concordance between urine and stone bacteria. E midstream urine specimen was cultured from each patient before surgical stone removal. Antimicrobial susceptibility of the isolates was determined by the Kirby–Bauer disc-diffusion method on Muller–Hinton agar (MHA) according to Clinical Laboratory Standards Institute (CLSI) guidelines [10]. E qualitative biochemical analysis of compositions of each stone was done for carbonate, calcium, magnesium, phosphate, oxalate, uric acid, and cysteine, using stone powder derived from the second part of stone sections (as aforementioned) that was left after bacterial culture [11].
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