Significant bacteriuria in outpatient diabetic and non-diabetic persons

Asymptomatic Bacteriuria (ASB) in diabetic patients: Treat or not to treat: A prospective, observational study conducted at a tertiary care hospital

Background:

The term asymptomatic bacteriuria (ASB) refers to the isolation of bacteria in a urine specimen of individuals who denied symptoms of urinary tract infection. Diabetes mellitus (DM) is a disease involving multiple organ systems, hallmarked for its chronicity and thus-forth endless complications including asymptomatic bacteriuria.

Objectives:

This study aimed to determine the characteristics of asymptomatic bacteriuria and antibiotic susceptibility pattern amongst patients with diabetes.

Settings and Design:

A prospective observational study was conducted at a tertiary care hospital in Karachi, Pakistan.

Methods and Material:

The study included all those patients with a diagnosis of diabetes with no signs and symptoms of urinary tract infection but showing the growth of an organism in urine culture. Pregnant females and subjects who used antibiotics in last two weeks were excluded. A total of 222 urine cultures were observed prospectively who met the inclusion criteria through non-probability consecutive sampling.

Results:

Out of 222 urine cultures observed, mean age of subjects were 62.89 ± 13.77 out of which 76% were females, and 61% had a family history of diabetes. The most frequent organisms isolated were Escherichia. Coli (E. Coli), Enterococcus, Klebsiella, Pseudomonas, and Enterobacter species. A total of 20 subjects got dual bacterial growth in their cultures among which 17 subjects had a growth of Enterococcus with any other pathogen causing UTI. Gender, family history of diabetes, levels of HBA1c, and older age groups all were found significantly associated with ASB.

Conclusions:

Our study is the first to analyze and study the associated risk factors amongst ASB in DM patients, and to identify the pathogens involved along with assessing their antibiotic resistance profiles. Also, due to the increase resistance to antibiotics we would recommend to use antibiotics in ASB patients only if they have any two or more comorbidities.

Characteristics of Asymptomatic Bacteriuria in Diabetes Mellitus Patients: A Retrospective Observational Study

Background and objective

The term asymptomatic bacteriuria (ASB) refers to the isolation of bacteria in a urine specimen of individuals without any symptoms of urinary tract infection (UTI). Diabetes mellitus (DM) is a disease involving multiple organ systems, characterized by its chronicity and hence endless complications including ASB. This study aimed to determine the characteristics of ASB and antibiotic susceptibility patterns among patients with diabetes.

Materials and methods

This was a retrospective observational study conducted in a tertiary care hospital. The study included patients with a diagnosis of diabetes with no signs and symptoms of UTI but who still showed the growth of an organism in urine culture. A total of 222 urine cultures were analyzed retrospectively, ensuring that they met the inclusion criteria through non-probability consecutive sampling.

Results

The mean age of the study participants was 62.89 ± 13.77 years; 76% of them were females, and 61% had a family history of diabetes. The most frequent organisms isolated were Escherichia coli (E. coli), Enterococcus, Klebsiella pneumonia, Pseudomonas aeruginosa, and Enterobacter species. A total of 20 subjects had dual bacterial growth in their cultures, with Enterococcus species (n=17) being the most common organism. Gender, family history of diabetes, levels of hemoglobin A1c (HbA1c), and advanced age were all found significantly associated with ASB.

Conclusion

Our study is the first of its kind to analyze and examine the risk factors associated with ASB in DM patients, and to identify the pathogens involved, along with assessing their antibiotic resistance profiles.

Results, meta-analysis and a first evaluation of UNOxR, the urinary nitrate-to-nitrite molar ratio, as a measure of nitrite reabsorption in experimental and clinical settings

We recently found that renal carbonic anhydrase (CA) is involved in the reabsorption of inorganic nitrite (NO₂^-), an abundant reservoir of nitric oxide (NO) in tissues and cells. Impaired NO synthesis in the endothelium and decreased NO bioavailability in the circulation are considered major contributors to the development and progression of renal and cardiovascular diseases in different conditions including diabetes. Isolated human and bovine erythrocytic CAII and CAIV can convert nitrite to nitrous acid (HONO) and its anhydride N₂O₃ which, in the presence of thiols (RSH), are further converted to S-nitrosothiols (RSNO) and NO. Thus, CA may be responsible both for the homeostasis of nitrite and for its bioactivation to RSNO/NO. We hypothesized that enhanced excretion of nitrite in the urine may contribute to NO-related dysfunctions in the renal and cardiovascular systems, and proposed the urinary nitrate-to-nitrite molar ratio, i.e., U_NOxR, as a measure of renal CA-dependent excretion of nitrite. Based on results from clinical and experimental animal studies, here, we report on a first evaluation of U_NOxR. We determined U_NOxR values in preterm neonates, healthy children, and adults, in children suffering from type 1 diabetes mellitus (T1DM) or Duchenne muscular dystrophy (DMD), in elderly subjects suffering from chronic rheumatic diseases, type 2 diabetes mellitus (T2DM), coronary artery disease (CAD), or peripheral arterial occlusive disease (PAOD). We also determined U_NOxR values in healthy young men who ingested isosorbide dinitrate (ISDN), pentaerythrityl tetranitrate (PETN), or inorganic nitrate. In addition, we tested the utility of U_NOxR in two animal models, i.e., the LEW.1AR1-iddm rat, an animal model of human T1DM, and the APOE*3-Leiden.CETP mice, a model of human dyslipidemia. Mean U_NOxR values were lower in adult patients with rheumatic diseases (187) and in T2DM patients of the DALI study (74) as compared to healthy elderly adults (660) and healthy young men (1500). The intra- and inter-variabilities of U_NOxR were of the order of 50% in young and elderly healthy subjects. U_NOxR values were lower in black compared to white boys (314 vs. 483, P = 0.007), which is in line with reported lower NO bioavailability in black ethnicity. Mean U_NOxR values were lower in DMD (424) compared to healthy (730) children, but they were higher in T1DM children (1192). ISDN (3 × 30 mg) decreased stronger U_NOxR compared to PETN (3 × 80 mg) after 1 day (P = 0.046) and after 5 days (P = 0.0016) of oral administration of therapeutically equivalent doses. In healthy young men who ingested NaNO₃ (0.1 mmol/kg/d), U_NOxR was higher than in those who ingested the same dose of NaCl (1709 vs. 369). In LEW.1AR1-iddm rats, mean U_NOxR values were lower than in healthy rats (198 vs. 308) and comparable to those in APOE*3-Leiden.CETP mice (151).

Simultaneous pentafluorobenzyl derivatization and GC-ECNICI-MS measurement of nitrite and malondialdehyde in human urine: Close positive correlation between these disparate oxidative stress biomarkers

Urinary nitrite and malondialdehyde (MDA) are biomarkers of nitrosative and oxidative stress, respectively. At physiological pH values of urine and plasma, nitrite and MDA exist almost entirely in their dissociated forms, i.e., as ONO^- (ONOH, pK_a=3.4) and ^-CH(CHO)₂ (CH₂(CHO)₂, pK_a=4.5). Previously, we reported that nitrite and MDA react with pentafluorobenzyl (PFB) bromide (PFB-Br) in aqueous acetone. Here, we report on the simultaneous derivatization of nitrite and MDA and their stable-isotope labeled analogs O¹⁵NO^- (4μM) and CH₂(CDO)₂ (1μM or 10μM) with PFB-Br (10μL) to PFBNO₂, PFB¹⁵NO₂, C(PFB)₂(CHO)₂), C(PFB)₂(CDO)₂ by heating acetonic urine (urine-acetone, 100:400μL) for 60min at 50°C. After acetone evaporation under a stream of nitrogen, derivatives were extracted with ethyl acetate (1mL). A 1-μL aliquot of the ethyl acetate phase dried over anhydrous Na₂SO₄ was injected in the splitless mode for simultaneous GC-MS analysis in the electron capture negative-ion chemical ionization mode. Quantification was performed by selected-ion monitoring (SIM) the anions [M-PFB]^-m/z 46 for ONO^-, m/z 47 for O¹⁵NO^-, m/z 251 for ^-C(PFB)(CHO)₂, and m/z 253 for ^-C(PFB)(CDO)₂. The retention times were 3.18min for PFB-ONO₂/PFB-O¹⁵NO₂, and 7.13min for ^-C(PFB)(CHO)₂/^-C(PFB)(CDO)₂. Use of CH₂(CDO)₂ at 1μM but not at 10μM was associated with an unknown interference with the C(PFB)₂(CDO)₂ peak. Endogenous MDA can be quantified using O¹⁵NO^- (4μM) and CH₂(CDO)₂ (10μM) as the internal standards. The method is also useful for the measurement of nitrate and creatinine in addition to nitrite and MDA. Nitrite and MDA were measured by this method in urine of elderly healthy subjects (10 females, 9 males; age, 60-70 years; BMI, 25-30kg/m²). Creatinine-corrected excretion rates did not differ between males and females for MDA (62.6 [24-137] vs 80.2 [52-118]nmol/mmol, P=0.448) and for nitrite (102 [71-174] vs. 278 [110-721]nmol/mmol P=0.053). We report for the first time a close correlation (r=0.819, P<0.0001) between MDA and nitrite in human urine. This correlation is assumed to be due to involvement of myeloperoxidase which catalyzes the formation of hypochlorite (^-OCl) from chloride and hydrogen peroxide. In turn, hypochlorite reacts both with nitrite and with polyunsaturated fatty acids such as arachidonic acid, with the later reaction generating MDA. The proposed mechanisms are supported by the literature but remain to be fully explored.

Asymptomatic Bacteriuria in Noncatheterized Adults

Asymptomatic bacteriuria (ASB) is a common finding and frequently detected in premenopausal nonpregnant women, institutionalized patients, patients with diabetes mellitus, and the ambulatory elderly population. Despite clear recommendations regarding diagnosis and management of ASB in these populations from the Infectious Diseases Society of America (IDSA), there remains an alarming rate of antimicrobial overuse. This article reviews definitions of ASB, epidemiology of ASB, literature surrounding ASB in diabetic patients, risk factors of ASB, microbiologic data regarding bacterial virulence, use of ASB strains for treatment of symptomatic urinary tract infection, and approaches to addressing translational barriers to implementing IDSA recommendations regarding diagnosis and management of ASB.

Approach to a positive urine culture in a patient without urinary symptoms

Asymptomatic bacteriuria (ASB) is a condition in which bacteria are present in a noncontaminated urine sample collected from a patient without signs or symptoms related to the urinary tract. ASB must be distinguished from symptomatic urinary tract infection (UTI) by the absence of signs and symptoms compatible with UTI or by clinical determination that a nonurinary cause accounts for the patient's symptoms. The overall purpose of this review is to promote an awareness of ASB as a distinct condition from UTI and to empower clinicians to withhold antibiotics in situations in which antimicrobial treatment of bacteriuria is not indicated.

Prevalence of asymptomatic bacteriuria in type 2 diabetic subjects with and without microalbuminuria

BACKGROUND

Diabetic subjects, especially women, show high prevalence of asymptomatic bacteriuria (ASB). The aim of the present study was to evaluate the prevalence of ASB in subjects with type 2 diabetes mellitus (T2D) with and without microalbuminuria (MA).

FINDINGS

A hundred diabetic subjects with MA (53 males/47 females, mean age +/- standard deviation: 65.5 +/- 11.1 years) and 100 diabetic subjects without MA (52 males/48 females, mean age +/- standard deviation: 65.4 +/- 11.3 years), consecutively attending the outpatient diabetes clinic of our hospital were recruited in the study. Subjects with overt diabetic nephropathy or nephropathy from other causes were excluded. In addition, subjects with symptoms of urinary track infection or use of antimicrobial drugs in the last 14 days were excluded by the study.Diabetic subjects with MA showed increased prevalence of ASB compared to diabetic subjects without MA (21% versus 8%, P < 0.001, respectively). Escherichia coli was the most prevalent pathogen isolated in diabetic subjects with and without MA (12% versus 3.0%, P = 0.01, respectively) followed by Proteus mirabilis (6% versus 5%, P = 0.75, respectively) and Klebsiella spp (5% versus 1%, P = 0.09, respectively). Univariate logistic analysis showed that ASB was associated with the presence of coronary artery disease [odds ratio (OR): 0.29, 95% Confidence Intervals (95% CI): 0.09-0.95, P = 0.04] and gender (OR: 0.09, 95% CI: 0.02-0.35, P < 0.001) in the diabetic study group with MA.

CONCLUSIONS

ASB is more prevalent among T2D subjects with MA. Screening for ASB is warranted in diabetic patients especially if pyuria is detected in urine analysis since ASB has been found to be a risk factor for developing symptomatic urinary tract infection.