Systematic radiologic detection of kidney stones in Canadian children: a new era of asymptomatic stones?

INTRODUCTION: Asymptomatic, or incidental, pediatric kidney stones detected on abdominal imaging pose a clinical challenge as their significance and expected outcome are not well described. OBJECTIVE: Our primary objective was to estimate the incidence of nephrolithiasis in pediatric patients undergoing abdominal ultrasound (US) or computerized tomography (CT), for all indications, in a pediatric tertiary care hospital. Our secondary objective was to determine the clinical outcome of these radiographically detected stones. METHODS: All abdominal US or CT radiology reports for patients younger than 18 years between January 1, 2011, and December 31, 2016, were retrieved. Reports were automatically flagged using textual analysis if they contained one of the 32 keywords potentially indicating nephrolithiasis. Flagged reports, as well as 10% of unflagged reports, were reviewed to confirm the radiologist impression of presence or absence of stones. Patient and stone-related clinical data were extracted. RESULTS: Two thousand four hundred forty-nine (5%) of 53 235 imaging reports cited at least one of the keywords. Manual review of flagged reports identified 498 studies having a radiologist impression of stones (244 unique patients). Stone incidence in children undergoing abdominal imaging more than doubled between 2011 and 2016. Medical record review found that 140 patients (57%) were symptomatic, while the other 104 patients (43%) were asymptomatic. Spontaneous resolution was greater (57% vs 34%) in asymptomatic patients compared to symptomatic patients. Asymptomatic patients were younger with a median age of 0.6 compared to 12.3 years. Asymptomatic and symptomatic stones were followed up for similar lengths of time (2.3 vs 2.0 years, p > 0.05) and had a similar number of follow-up USs (3.9 vs 4.6 studies, p > 0.05). CONCLUSIONS: The incidence of radiologically identified stones in children undergoing abdominal imaging at our center increased over time. Asymptomatic stones follow a benign course with minimal need for intervention; however, they were detected almost as frequently as symptomatic stones. Asymptomatic stones may represent increased healthcare resource utilization due to similar follow-up compared to symptomatic stones. Further research regarding the optimal imaging intervals and long-term follow-up for asymptomatic stones is warranted.

The Prevalence, Clinicodemographics, and Outcomes of Incidental and Symptomatic Renal Cysts in a Pediatric Cohort Undergoing Ultrasonography.

PURPOSE: The growing availability of modern-day imaging has resulted in an increase in the number of renal cysts detected in the pediatric population. Few publications have reported outcomes of these childhood cysts. In this study we assessed the prevalence and evolution of renal cysts in children, and described clinical characteristics, mode of presentation and ultimate outcomes. MATERIALS AND METHODS: Our institutional ultrasound database was searched for all abdominal ultrasound reports from 2006 to 2017. These reports were then cross-referenced with a manual retrospective chart review. Clinical characteristics including mode of presentation, cyst characteristics, and outcomes were analyzed using descriptive and nonparametric statistical methods. RESULTS: Of 70,500 abdominal ultrasound scans during the study period 1,531 (2.2%) met the study inclusion criteria. Overall 26% of cysts were complex and 10.1% of cases were associated with hydronephrosis. Echogenic kidneys were more likely to be associated with simple cysts (p=0.0001). There was no difference between cyst diameter and symptomatology (p=0.82). The conversion of simple to complex renal cysts was less than 1% and 1.8% of complex cysts developed renal cell carcinoma. CONCLUSIONS: In a large cohort of children who underwent abdominal imaging we found a 10-year renal cyst prevalence of 2.2%. Given that nearly all cysts follow a benign course and that simple cysts will invariably grow within 2 years, we believe that these cases could be safely discharged after that point. We continue to recommend surveillance for patients with cysts larger than 15 mm, complex cysts, family history of adult polycystic kidney disease or those with concomitant genitourinary anomalies requiring ongoing followup.

Impact of transport crate reuse and of catching and processing on Campylobacter and Salmonella contamination of broiler chickens.

The influence of transport, catching, and processing on contamination of broiler chickens with Salmonella and Campylobacter was investigated. Transport crates were reused with high frequency and were often still contaminated with Salmonella and Campylobacter when they arrived at the farm despite the fact that they were washed at the factory, and thus they were a potential route of infection. These organisms contaminated the feathers of previously Campylobacter- and Salmonella-negative birds going to the processing plant and were isolated from processed carcasses, albeit at a low frequency. The Campylobacter types which were the predominant organisms on the live birds when they arrived at the processing plant were not necessarily the types that were most frequently isolated from processed carcasses. This finding may reflect cross-contamination that occurred during processing or differences in the tolerance of the strains to the hostile environments that the bacteria experienced. The process of catching and putting the birds in crates significantly increased the chance of contamination with Campylobacter (P < 0.001).

Characterisation of cytolethal distending toxin (CDT) mutants of Campylobacter jejuni.

In order to assess the contribution of cytolethal distending toxin (CDT) to the toxigenicity and pathogenicity of Campylobacter jejuni, the C. jejuni 81-176 and C. jejuni NCTC 11168 CDTs were inactivated by insertional mutation of the cdtB toxin subunit. Cell-free sonicates from isogenic C. jejuni 81-176 cdtB- strains were found to be greatly attenuated in HeLa cytotoxicity assays, whilst still retaining some toxigenicity. Sonicates from a C. jejuni NCTC 11168 cdtB- strain produced no detectable cytotoxicity. When orally administered to adult severe combined immunodeficient (SCID) mice, C. jejuni cdtB mutant strains were unaffected in enteric colonisation abilities but demonstrated impaired invasiveness into blood, spleen and liver tissues. These data suggest that CDT may be the principal toxin produced by this species and that some C. jejuni strains may generate additional toxigenic factor(s) distinct from CDT.

Pathogenicity in isolates of Salmonella enterica serotype Enteritidis PT4 which differ in RpoS expression: effects of growth phase and low temperature.

Experiments with 2 wild type isolates of Salmonella enterica serotype Enteritidis PT4, which differed in RpoS expression, tolerance to certain hostile environments and pathogenicity, found that changes in in vitro acid, heat, or peroxide tolerance had no effect on the ability of the isolates to multiply in the spleens of C57/BL7/J mice infected orally. Thus, with the pathogenic RpoS-positive isolate, the infectivity of log phase chilled cells, which are profoundly acid-sensitive, was the same as that of non-chilled stationary phase cells which are acid-tolerant. Similarity the infectivity of the RpoS-negative, sensitive isolate, was not enhanced by increases in any tolerance. The ability to survive on surfaces, like infectivity, was also largely unaffected by either growth phase or cold exposure. These two attributes may thus be related and, given that the pathogenic PT4 isolate is capable of prolonged survival and the nonpathogenic isolate survives poorly, survival could serve as a potential marker of pathogenicity. Although the pathogenicity of the two isolates was very different, they showed an almost identical increase in acid tolerance following culture at pH 4.0 for up to 60 min.

Isolates of Salmonella enterica Enteritidis PT4 with enhanced heat and acid tolerance are more virulent in mice and more invasive in chickens.

Two Enteritidis PT4 isolates which differed in inherent tolerance to heat, acid, H2O2 and the ability to survive on surfaces were used to infect mice, day-old chicks or laying hens. The acid-, heat-, H2O2- and surface-tolerant isolate was more virulent in mice and more invasive in laying hens, particularly in reproductive tissue. However, no significant differences were observed in behaviour in chicks. Both PT4 isolates were able to infect chicks housed in the same room as infected birds, although the heat-tolerant isolate survived significantly better than the heat-sensitive one in aerosols.

Observations on the control of Campylobacter jejuni infection of poultry by 'competitive exclusion'.

Various bacteria were isolated aerobically from caecal mucus of campylobacter-free broilers sampled at slaughter. The organisms were mainly presumptive coliform bacteria, enterococci and Micrococcus/Staphylococcus spp. None showed any inhibitory activity against Campylobacter jejuni in a plate assay. On the other hand, adult hens yielded nine strains of Escherichia coli and one strain of Enterococcus faecium that were positive in the plate assay and most of which utilized mucin as an energy source. Coliform bacteria with these properties were also isolated from samples of pig colon and faeces and associated environmental samples. All of the strains from chickens or pigs failed as separate mixtures to protect chicks against a challenge dose of 10(4)-10(5) cfu/bird of C. jejuni. By contrast, chicks dosed with anaerobic preparations of caecal mucus from campylobacter-free adult hens were partly protected against C. jejuni, as shown by values for Protection Factor (mean log(10) of camplylobacters/g in caecal content of control chicks divided by corresponding mean for treated group). Materials from three hens gave values of 7.3, 1.4 and 3.6, respectively.

Salmonella enteritidis phage type 4 isolates more tolerant of heat, acid, or hydrogen peroxide also survive longer on surfaces.

In a comparative study of different Salmonella enteritidis phage type 4 isolates we found that those isolates with enhanced heat tolerance also survived better than isolates that were heat sensitive either at pH 2.6, in 10 mM H2O2, or on surfaces. Culture to the stationary phase increased the heat tolerance of all isolates and the acid and H2O2 tolerance of heat-tolerant isolates. With heat-sensitive isolates, however, extended culture had no impact on survival in H2O2 and only a marginal impact on acid tolerance. The growth phase had no appreciable impact on the surface survival of any of the isolates.

Pyelonephritis in pregnancy: once-a-day ceftriaxone versus multiple doses of cefazolin. A randomized, double-blind trial.

OBJECTIVE: The purpose of this study was to compare the efficacy of a single daily dose of intravenous ceftriaxone with that of multiple-dose cefazolin in the treatment of acute pyelonephritis in pregnancy. STUDY DESIGN: This was a double-blind, randomized, clinical trial. Patients admitted to the hospital with the diagnosis of acute pyelonephritis in pregnancy were enrolled and randomized according to a computer-generated randomization schedule. The study group received a single daily 1 gm dose of ceftriaxone intravenously along with two additional doses of normal saline solution. The comparison group received three daily 2 gm doses of cefazolin intravenously. All infusions were given on an 8-hour schedule. Treatments were continued until the patient became afebrile. Each patient was discharged from the hospital on a regimen of appropriate oral antibiotics as directed by urine culture and sensitivities. At follow-up visits test-of-cure cultures were obtained. RESULTS: During the 2-year study period, 178 patients were randomized: 88 received cefazolin and 90 ceftriaxone. Patient demographics and presenting signs and symptoms were similar in both groups. No differences were noted between the groups regarding days of febrile morbidity, length of hospital stay, or treatment failures. CONCLUSIONS: Daily single-dose intravenous ceftriaxone is as effective as multiple-dose cefazolin in the treatment of patients with acute pyelonephritis during pregnancy.