Pilot- and bench-scale testing of faecal indicator bacteria survival in marine beach sand near point sources

AIM

Factors affecting faecal indicator bacteria (FIB) and pathogen survival/persistence in sand remain largely unstudied. This work elucidates how biological and physical factors affect die-off in beach sand following sewage spills.

METHODS AND RESULTS

Solar disinfection with mechanical mixing was pilot-tested as a disinfection procedure after a large sewage spill in Los Angeles. Effects of solar exposure, mechanical mixing, predation and/or competition, season, and moisture were tested at bench scale. First-order decay constants for Escherichia coli ranged between -0.23 and -1.02 per day, and for enterococci between -0.5 and -1.0 per day. Desiccation was a dominant factor for E. coli but not enterococci inactivation. Effects of season were investigated through a comparison of experimental results from winter, spring, and fall.

CONCLUSIONS

Moisture was the dominant factor controlling E. coli inactivation kinetics. Initial microbial community and sand temperature were also important factors. Mechanical mixing, common in beach grooming, did not consistently reduce bacterial levels.

SIGNIFICANCE AND IMPACT OF THE STUDY

Inactivation rates are mainly dependent on moisture and high sand temperature. Chlorination was an effective disinfection treatment in sand microcosms inoculated with raw influent.

Effect of increasing vertebral marrow fat content on BMD measurement, T-Score status and fracture risk prediction by DXA

Quantitative examination of iliac crest bone biopsies shows that as subjects become older bone and functional marrow are replaced by adipose tissue. Studies of vertebral marrow fat using nuclear magnetic resonance spectroscopy ((1)H-MRS) show that subjects with lower spine T-scores have significantly higher marrow fat content. These findings suggest that the ability of DXA scans to determine fracture risk may be partly explained by the effect of increased marrow fat on BMD. However, a proper evaluation of the relationship between WHO spine T-score status and marrow fat content requires that the BMD data are first corrected for the bias caused by a selection effect in which subjects with higher marrow fat are more likely to be identified as having osteoporosis. In this study we have therefore reanalysed previously published data for 185 elderly Hong Kong Chinese subjects (103 women, mean age 73 y; 82 men, mean age 73 y) who had spine DXA scans and (1)H-MRS measurements of L3 marrow fat. The effect of varying marrow fat on BMD was modelled using vertebral body thicknesses measured in 50 men and women. Spine T-scores in each individual were adjusted for the measured marrow fat. Subjects were assigned to WHO categories based on their corrected T-scores, and the relationship between marrow fat and T-score status evaluated using regression analysis and analysis of variance. The average change in percent marrow fat per T-score unit was used to infer the fraction of the spine BMD fracture discrimination explained by marrow composition. The mean (SD) of the L1-L4 vertebral body thickness was 30.2 (2.1) mm for Hong Kong women and 33.4 (2.5) mm for men. A change in marrow fat content from 0 to 100% was estimated to produce a BMD decrease of 0.14 g/cm(2) (1.3 T-score units) in women and 0.16 g/cm(2) (1.3 T-score units) in men. Although adjusting spine BMD for marrow fat reduced the significance of the correlation, there was still a trend for marrow fat to increase with decreasing T-score with a slope of -1.2+/-0.7% per T-score unit (p=0.078) for women and -1.4+/-0.6% per T-score unit (p=0.023) for men. When the effect of marrow composition on fracture discrimination was evaluated the results showed that the higher vertebral marrow fat content found in osteoporotic subjects made a negligible contribution to the ability of spine BMD measurements to predict fracture risk.

Water quality indicators and the risk of illness at beaches with nonpoint sources of fecal contamination

BACKGROUND

Indicator bacteria are a good predictor of illness at marine beaches that have point sources of pollution with human fecal content. Few studies have addressed the utility of indicator bacteria where nonpoint sources are the dominant fecal input. Extrapolating current water-quality thresholds to such locations is uncertain.

METHODS

In a cohort of 8797 beachgoers at Mission Bay, California, we measured baseline health at the time of exposure and 2 weeks later. Water samples were analyzed for bacterial indicators (enterococcus, fecal coliforms, total coliforms) using both traditional and nontraditional methods, ie, chromogenic substrate or quantitative polymerase chain reaction. A novel bacterial indicator (Bacteroides) and viruses (coliphage, adenovirus, norovirus) also were measured. Associations of 14 health outcomes with both water exposure and water quality indicators were assessed.

RESULTS

Diarrhea and skin rash incidence were the only symptoms that were increased in swimmers compared with nonswimmers. The incidence of illness was not associated with any of the indicators that traditionally are used to monitor beaches. Among nontraditional water quality indicators, associations with illness were observed only for male-specific coliphage, although a low number of participants were exposed to water at times when coliphage was detected.

CONCLUSIONS

Traditional fecal indicators currently used to monitor these beaches were not associated with health risks. These results suggest a need for alternative indicators of water quality where nonpoint sources are dominant fecal contributors.

Comparison and verification of bacterial water quality indicator measurement methods using ambient coastal water samples

More than 30 laboratories routinely monitor water along southern California's beaches for bacterial indicators of fecal contamination. Data from these efforts frequently are combined and compared even though three different methods (membrane filtration (MF), multiple tube fermentation (MTF), and chromogenic substrate (CS) methods) are used. To assess data comparability and quantify variability within method and across laboratories, 26 laboratories participated in an intercalibration exercise. Each laboratory processed three replicates from eight ambient water samples employing the method or methods they routinely use for water quality monitoring. Verification analyses also were conducted on a subset of wells from the CS analysis to confirm or exclude the presence of the target organism. Enterococci results were generally comparable across methods. Confirmation revealed a 9% false positive rate and a 4% false negative rate in the CS method for enterococci, though these errors were small in the context of within- and among-laboratory variability. Fecal coliforms also were comparable across all methods, though CS underestimated the other methods by about 10%, probably because it measures only E. coli, rather than the larger fecal coliform group measured by MF and MTF. CS overestimated total coliforms relative to the other methods by several fold and was found to have a 40% false positive rate in verification. Across-laboratory variability was small relative to within- and among-method variability, but only after data entry errors were corrected. One fifth of the laboratories committed data entry errors that were much larger than any method-related errors. These errors are particularly significant because these data were submitted in a test situation where laboratories were aware they would be under increased scrutiny. Under normal circumstances, it is unlikely that these errors would have been detected and managers would have been obliged to issue beach water quality warnings.

Multitiered approach using quantitative PCR to track sources of fecal pollution affecting Santa Monica Bay, California

The ubiquity of fecal indicator bacteria such as Escherichia coli and Enterococcus spp. in urban environments makes tracking of fecal contamination extremely challenging. A multitiered approach was used to assess sources of fecal pollution in Ballona Creek, an urban watershed that drains to the Santa Monica Bay (SMB) near Los Angeles, Calif. A mass-based design at six main-stem sites and four major tributaries over a 6-h period was used (i) to assess the flux of Enterococcus spp. and E. coli by using culture-based methods (tier 1); (ii) to assess levels of Enterococcus spp. by using quantitative PCR and to detect and/or quantify additional markers of human fecal contamination, including a human-specific Bacteroides sp. marker and enterovirus, using quantitative reverse transcriptase PCR (tier 2); and (iii) to assess the specific types of enterovirus genomes found via sequence analysis (tier 3). Sources of fecal indicator bacteria were ubiquitous, and concentrations were high, throughout Ballona Creek, with no single tributary dominating fecal inputs. The flux of Enterococcus spp. and E. coli averaged 10(9) to 10(10) cells h(-1) and was as high at the head of the watershed as at the mouth prior to discharge into the SMB. In addition, a signal for the human-specific Bacteroides marker was consistently detected: 86% of the samples taken over the extent during the study period tested positive. Enteroviruses were quantifiable in 14 of 36 samples (39%), with the highest concentrations at the site furthest upstream (Cochran). These results indicated the power of using multiple approaches to assess and quantify fecal contamination in freshwater conduits to high-use, high-priority recreational swimming areas.

Bone mineral density and the risk of peripheral arterial disease in men and women: results from Mr. and Ms Os, Hong Kong

Previous population studies have demonstrated an association between peripheral vascular disease and bone mineral density in women, but not in men. In a large prospective cohort of 3,998 Chinese men and women aged 65 to 92 years of age in Hong Kong, the association between peripheral vascular disease and bone mineral density was explored. Demographic and lifestyle information was obtained from face to face interviews using a standardized questionnaire. This included demographic information, medical history and lifestyle factors. Physical examination measurements included anthropometry and tibial and brachial systolic blood pressures. The ratio of the posterior tibial and brachial systolic blood pressures, the ankle/arm index, was used as a measure of peripheral arteriosclerosis in the lower extremities. Bone mineral density (BMD) at the total hip and spine (L1-L4) was measured by Hologic QDR-4500 W densitometers (Hologic, Inc., Waltham, Mass.). In this cross-sectional analysis, the ankle brachial index (ABI) was positively correlated with hip BMD (correlation coefficient=0.27; P<0.001). However, after adjustment for confounders, the correlation became much weaker (correlation coefficient=0.03; P<0.05). This showed that much of the relationship between ABI and BMD could be explained by other confounders. In multiple regression analysis, an increase in ABI of 1 SD of ABI was associated with an increase of 0.5% (95% CI: 0.02%, 0.9%) in hip BMD after adjusting for age, sex, body weight, smoking status, history of diabetes, cardiovascular diseases, use of thiazide diuretics, grip strength and physical activity. Although our study shows that peripheral vascular disease in the lower extremities may be associated with decreased bone mineral density, the association is weak especially after adjustment was made for confounders. This indicates that other factors may be contributing to the association between peripheral vascular disease and osteoporosis.

Bone Scintigraphy in Common Tumors With Osteolytic Components

Osteolytic lesions are frequently encountered in clinical practice. Radionuclide bone scans with technetium-99m-labeled diphosphonates are often performed in the evaluation of both solitary and multiple osteolytic lesions. In this pictorial review, we critically evaluate the current role of bone scan in common osteolytic tumors including aneurysmal bone cyst, simple bone cyst, fibrous dysplasia, nonossifying fibroma, giant cell tumor, eosinophilic granuloma, enchondroma, chondrosarcoma, osteosarcoma, Ewing sarcoma, myeloma, and metastases. The merits and limitations of bone scanning are emphasized.

Computed tomography for cervical spine trauma. The impact of MDCT on fracture detection and dose deposition

A multidetector computed tomography (MDCT) was installed in our department. Referral rates, examination protocols and detection rates of abnormal findings in CT examinations for cervical spine trauma 6 months before and 6 months after MDCT installation were compared to look for changes in practice. Retrospective analysis of all CT cervical spine examinations in patients with multiple trauma over two contiguous 6-month periods: from July 2003 to December 2003 (helical CT) and from January 2004 to June 2004 (MDCT). Variables recorded were number of CT examinations performed, scan plane coverage and traumatic abnormalities detected. Phantom dosimetry measurements for cervical spine examination in both helical CT and MDCT were compared. One hundred and fifty four patients underwent cervical spine CT during these periods. Helical CT period: of 91 patients undergoing CT cervical spine examination for trauma, 65 (71%) were complete cervical examinations and 26 (29%) were level-specific examinations. Eight patients (9%) had cervical spine fracture, six of which were apparent on radiographs. Dose estimations for thyroid, lens and breast were 24.76, 1.86 and 0.21 mGy, respectively, for complete cervical spine examinations. MDCT period: of 63 patients who underwent CT cervical spine examination for trauma, 61 (97%) were complete examinations and 2 (3%) were level-specific examinations. Six patients (11%) had cervical spine fracture, three of which were apparent on radiographs. Dose estimations for thyroid, lens and breast were 75.8, 9.7 and 0.7 mGy, respectively, for complete cervical spine examinations, which were notably higher than those for helical CT. After installation of MDCT, clinical requests for complete examination of the cervical spine following trauma increased. This changing trend resulted in a significantly higher radiation dose to thyroid, lens and breast.

Musculoskeletal infections: ultrasound appearances

Musculoskeletal infections are commonly encountered in clinical practice. This review will discuss the ultrasound appearances of a variety of musculoskeletal infections such as cellulitis, infective tenosynovitis, pyomyositis, soft-tissue abscesses, septic arthritis, acute and chronic osteomyelitis, and post-operative infection. The peculiar sonographic features of less common musculoskeletal infections, such as necrotizing fasciitis, and rice body formation in atypical mycobacterial tenosynovitis, and bursitis will also be presented.

Early magnetic resonance imaging of radiographically occult osteoporotic fractures of the femoral neck

Osteoporosis is associated with thinning of cortical and trabecular bone, which reduces bone strength and predisposes individuals to fracture development. Femoral neck fractures in patients with osteoporosis may not be apparent on radiographs. Magnetic resonance imaging is useful at detecting these radiographically occult fractures; yet, the practice has not been widely adopted in Hong Kong. In this article, we review our experience of early magnetic resonance imaging in this clinical context--that is, imaging performed within 48 hours of presentation to hospital. Twenty-eight patients (age range, 69-93 years) over a 3-year period were studied. Magnetic resonance imaging revealed radiographically occult neck fractures in 14 (50%) cases (equivalent to 4% of all femoral neck fractures). These fractures were treated surgically (64%) or conservatively (36%) with good bone healing and clinical outcome. When no femoral neck fracture was present, magnetic resonance imaging revealed an alternative cause for symptoms in all 14 cases. We strongly endorse the use of early magnetic resonance imaging for patients with osteoporosis who have a clinically suspected femoral neck fracture that is not visible radiographically.

Does Doppler analysis of musculoskeletal soft-tissue tumours help predict tumour malignancy?

AIM

To investigate whether analysing vascularity of soft-tissue tumours on ultrasound assists differentiating benign from malignant tumours.

MATERIALS AND METHODS

One hundred and forty-eight vascular soft-tissue tumours in 148 patients (88 males, mean age 45.6 years) were studied. Final diagnosis was established histologically in 95 (64%) of cases. For each tumour, three-colour Doppler imaging features (vascularity, vascular density, vascular organization) and 13 pulsed Doppler (spectral analysis) parameters were assessed. Data analysis was performed to isolate optimal discriminatory criteria for differentiating benign from malignant tumours.

RESULTS

Significantly more benign soft-tissue tumours had an organized vascular pattern on colour Doppler imaging. If the vascular pattern is organized, this is a good indicator of tumour benignity. However, this pattern was apparent in less then one-third of the soft-tissue tumours. Benign tumours also had significantly higher minimum end diastolic velocity (EDVmin) and lower mean ratio of resistive index (RImean) than malignant soft-tissue tumours, though considerable overlap existed between the two groups.

CONCLUSION

Colour Doppler imaging analysis of soft-tissue tumours is of limited value when differentiating benign from malignant tumours. If an organized vascular pattern is present, the tumour is more likely to be benign. Flow characteristics were not specific enough to be applicable in clinical practice.

Evaluation of microbial source tracking methods using mixed fecal sources in aqueous test samples

Microbiological source tracking (MST) methods are increasingly being used to identify fecal contamination sources in surface waters, but these methods have been subjected to limited comparative testing. In this study, 22 researchers employing 12 different methods were provided sets of identically prepared blind water samples. Each sample contained one to three of five possible fecal sources (human, dog, cattle, seagull or sewage). Researchers were also provided with portions of the fecal material used to inoculate the blind water samples for use as library material. No MST method that was tested predicted the source material in the blind samples perfectly. Host-specific PCR performed best at differentiating between human and non-human sources, but primers are not yet available for differentiating between all of the non-human sources. Virus and F+ coliphage methods reliably identified sewage, but were unable to identify fecal contamination from individual humans. Library-based isolate methods correctly identified the dominant source in most samples, but also had frequent false positives in which fecal sources not in the samples were incorrectly identified as being present. Among the library-based methods, genotypic methods generally performed better than phenotypic methods.

An unusual cause of carpal tunnel syndrome

Tuberculosis is an uncommon cause of carpal tunnel syndrome. We report a patient with systemic lupus erythematosus who developed hand numbness. Ultrasonic, operative and microbiological findings supported the diagnosis of median nerve compression secondary to a tuberculous abscess. The symptoms resolved with surgical excision and antituberculous chemotherapy.

Subcutaneous injection of metallic mercury

Deliberate self-injection of metallic mercury into subcutaneous tissue is uncommon. A 41-year-old lady with a history of schizophrenia was admitted to our hospital after deliberate injection of metallic mercury into her right wrist and antecubital fossa. Physical examination was unremarkable except for the injection marks over right antecubital fossa and wrist. The presence of subcutaneous mercury deposits in her right elbow and wrist was confirmed by X-rays and ultrasound scan. Three days later, erythema, swelling, induration and tenderness were seen over the injection sites. At the operation on day 9, mercury streaks were seen within the brachialis muscle belly, surrounded by friable necrotic tissues along the tract. A similar picture was noted in her right wrist. The necrotic tissues and mercury streaks were removed. The patient had been unco-operative and she only received incomplete treatment with dimercaprol and 2,3-dimercaptosuccinic acid. Her total blood mercury level (normal < 50 nmol/L) decreased from 101-151 nmol/L in the first two weeks to 42 nmol/L 3 months later. Her 24-hour urinary mercury excretion (normal < 10 nmol) changed from 55.7-209.5 nmol in the first 7 weeks to 125.4 nmol 3 months later. This case illustrates that soft tissue metallic mercury can produce local necrosis and may allow continuous absorption with persistent elevations in blood and urinary mercury levels. Therefore, early surgical removal of subcutaneous mercury deposits is required to prevent local complications and minimize the risk of systemic absorption and toxicity.

Rice-body formation in atypical mycobacterial tenosynovitis and bursitis: findings on sonography and MR imaging

OBJECTIVE

This article describes rice bodies found in patients with atypical mycobacterial tenosynovitis and bursitis, emphasizing the sonographic and MR imaging appearances of these small bodies.

CONCLUSION

Rice bodies occur in patients with atypical mycobacterial tenosynovitis and bursitis. When small, rice bodies are better visualized on MR imaging than on sonography, allowing the radiologist to consider appropriate diagnoses.

Pseudoaneurysm complicating osteochondromas: symptom relief with embolization

Pseudoaneurysm is a recognized vascular complication of osteochondromas. The diagnosis is confirmed by various imaging techniques including ultrasound, magnetic resonance imaging, and conventional angiography. Surgical repair and excision of the adjacent osteochondroma is considered the treatment of choice. The authors report a case of successful transarterial embolization using helical microcoils in the treatment of osteochondroma-related pseudoaneurysm of the superficial femoral artery. It resulted in complete obliteration of blood flow to the pseudoaneurysm and good symptomatic relief before subsequent semielective surgery. No complication was encountered during the procedure. Transarterial embolization is a safe mode of treatment in experienced hands. In patients with contraindications to surgery, embolization may be considered a definitive treatment.

Unusual muscle pain in two patients with diabetic renal failure

We report on two patients with diabetic muscle infarct, a painful musculoskeletal disorder complicating longstanding diabetes with established microangiopathy. Both patients had renal failure that was treated by dialysis. The underlying pathophysiological process was considered to be an arterial vascular event mediated through ischaemia-reperfusion injury. Clinicians should be alert to this condition. T2-weighted magnetic resonance imaging was valuable in establishing the diagnosis.

The clinical efficacy of neoadjuvant chemotherapy in squamous esophageal cancer: a prospective nonrandomized study of pulse and continuous-infusion regimens with Cisplatin and 5-Fluorouracil

BACKGROUND

We evaluated cisplatin and 5-fluorouracil as preoperative adjuvant chemotherapy for patients with locally advanced squamous esophageal cancer and compared two different infusion regimens. The outcomes were also compared with those of our historical control patients treated by surgery alone.

METHODS

From 1991 to 1997, 83 consecutive esophageal cancer patients underwent surgical exploration after completion of two cycles of cisplatin and 5-fluorouracil chemotherapy regimens, either in pulse or in continuous infusion cycles. Outcomes were compared with those of 76 historical control patients. Both groups were comparable in demographic characteristics and tumor stages. The resection rates, operative morbidity, mortality, and survival rates were compared.

RESULTS

Partial response was achieved in 50% of patients who received chemotherapy. There was no chemotherapy-related mortality. The resection, morbidity, and mortality rates and median survival between the surgery-alone group and the chemotherapy group were 71.1% vs. 82%, 51% vs. 55%, and 4% vs. 10.8%, 12.0 vs. 13.5 months, respectively (P >.05). There was also no statistically significant difference between the two regimens.

CONCLUSIONS

Preoperative adjuvant chemotherapy with cisplatin and 5-fluorouracil infusion, in pulse or continuous regimens, followed by surgery for squamous esophageal cancer patients had no added benefit in the overall survival.

Discriminatory sonographic criteria for the diagnosis of carpal tunnel syndrome

OBJECTIVE

Sonographic examination of the median nerve has been suggested as a useful alternative to electrophysiologic study in the diagnosis of carpal tunnel syndrome. To determine its usefulness and the best diagnostic criterion, sonograms of patients with the disease were compared with sonograms of healthy subjects in a case-control study.

METHODS

Patients with carpal tunnel syndrome and asymptomatic controls who were matched for age and sex were enrolled and underwent sonography of the wrists. Eight separate sonographic criteria were analyzed in each wrist. Data from the patient group and the control group were compared to establish optimal diagnostic criteria for carpal tunnel syndrome, using receiver operating characteristic analytic techniques.

RESULTS

Thirty-five patients with carpal tunnel syndrome and 35 asymptomatic controls were examined. Increased cross-sectional area of the median nerve was found to be the most predictive measure of carpal tunnel syndrome, proximal to the tunnel inlet, at the tunnel inlet, and at the tunnel outlet, with significant differences between patients and controls. Using a receiver operating characteristic curve, a cut-off value >0.098 cm(2) at the tunnel inlet provided a diagnostic sensitivity of 89% and a specificity of 83%.

CONCLUSION

Sonographic measurement of the median nerve cross-sectional area is both sensitive and specific for the diagnosis of carpal tunnel syndrome.