Biomedical subjects
Publications and source records attributed to L Riley.
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We assessed the susceptibility of Escherichia coli strains causing communityacquired urinary tract infection (UTI) in a large urban center in Brazil, comparing two different populations (patients with health insurance vs. uninsured). 581 nonduplicate strains of E. coli were isolated. The prevalence of antimicrobial resistance was greater than 20% for ampicillin (51%), trimethoprim-sulfamethoxazole (43%), tetracycline (41%) and chloramphenicol (22%). Overall, 12% of the E. coli isolates were resistant to ciprofloxacin. Resistance prevalences to most antimicrobials were similar in the two study populations. Our data provide much needed information on the prevalence of antimicrobial resistance among E. coli causing communityacquired UTI in Brazil. Antimicrobial resistance among strains of E. coli causing community-acquired UTIs was relatively high, particularly resistance to ciprofloxacin.
We enrolled 382 college-age women in a cross-sectional survey to investigate the relationship between use of over-the-counter (OTC) azole-based antifungal drugs and vaginal colonization by drug-resistant Candida. This study showed no correlation (P=.506) between previous OTC exposure and colonization of drug-resistant Candida in vaginal flora. However, a small number of resistant Candida species isolates were obtained from women with a history of multiple exposures to OTC antifungals; given the widespread use of these products, this may be an emerging concern.
Molecular biology techniques have become increasingly integrated into the practice of infectious disease epidemiology. The term "molecular epidemiology" routinely appears in the titles of articles that use molecular strain-typing ("fingerprinting") techniques-regardless of whether there is any epidemiologic application. What distinguishes molecular epidemiology is both the "molecular," the use of the techniques of molecular biology, and the "epidemiology," the study of the distribution and determinants of disease occurrence in human populations. The authors review various definitions of molecular epidemiology. They then comment on the range of molecular techniques available and present some examples of the benefits and challenges of applying these techniques to infectious agents and their affected host using tuberculosis and urinary tract infection as examples. They close with some thoughts about training future epidemiologists to best take advantage of the new opportunities that arise from integrating epidemiologic methods with modern molecular biology.
We measured water relations attributes of the terminal shoots of 3-year-old Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murr.) Parl.) seedlings that represented its geographic range. Pressure-volume curves were developed and osmotic potentials at full (psi(sf)) and zero turgor (psi(sz)), relative water content at zero turgor, and an index of tissue elasticity (IE) were calculated for 38 families during early, mid- and late summer at an inland nursery, and for 12 of these families during mid- and late summer at a coastal nursery. Compared with other conifer species, psi(sz) was high (-1.4 to -1.5 MPa) and declined in seedlings at both nurseries as the season progressed. Both IE and osmotic amplitude (psi(sf)-psi(sz)) increased during the season. Osmotic potential at zero turgor was lower and osmotic amplitude greater in seedlings at the inland nursery than at the coastal nursery. Correlations of water relations attributes with geographic location of the seed sources were weak and usually not significant. High elevation southern sources exhibited smaller differences in psi(sz) between nurseries than low elevation northern sources. The small differences in water relations attributes among sources and between nurseries suggest that some may be of marginal physiological importance; however, sources that produced larger seedlings appeared to be less desiccation tolerant. We conclude that, when moving genotypes during reforestation, decisions based on patterns in tree size and timing of growth will account for these small differences in water relations.
A patient with an allergy to a macrolide antibiotic was given tacrolimus and developed a sudden cutaneous reaction.
Mycobacterium tuberculosis and Salmonella enterica cause very different diseases and are only distantly related. However, growth within macrophages is crucial for virulence in both of these intracellular pathogens. Here, we demonstrate that in spite of the phylogenetic distance, M. tuberculosis and Salmonella employ a parallel survival strategy for growth within macrophage phagosomes. Previous studies established that the Salmonella mgtC gene is required for growth within macrophages and for virulence in vivo. M. tuberculosis contains an open reading frame exhibiting 38% amino acid identity with the Salmonella MgtC protein. Upon inactivation of mgtC, the resulting M. tuberculosis mutant was attenuated for virulence in cultured human macrophages and impaired for growth in the lungs and spleens of mice. Replication of the mgtC mutant was inhibited in vitro by a combination of low magnesium and mildly acidic pH suggesting that the M. tuberculosis-containing phagosome has these characteristics. The similar phenotypes displayed by the mgtC mutants of M. tuberculosis and Salmonella suggest that the ability to acquire magnesium is essential for virulence in intracellular pathogens that proliferate within macrophage phagosomes.
The Global Youth Tobacco Survey (GYTS) project was developed by the World Health Organization and the US Centers for Disease Control and Prevention to track tobacco use among youth in countries across the world, using a common methodology and core questionnaire. The GYTS is school based and employs a two-stage sample design to produce representative data on smoking among students aged 13-15 years. The first stage consists of a probabilistic selection of schools, and the second consists of a random selection of classes from the participating schools. All students in the selected classes are eligible for the survey. In 1999, the GYTS was conducted in 13 countries and is currently in progress in over 30 countries. This report describes data from 12 countries: Barbados, China, Costa Rica, Fiji, Jordan, Poland, the Russian Federation (Moscow), South Africa, Sri Lanka, Ukraine (Kiev), Venezuela, and Zimbabwe. The findings show that tobacco use in the surveyed age group ranged from a high of 33% to a low of 10%. While the majority of current smokers wanted to stop smoking, very few were able to attend a cessation programme. In most countries the majority of young people reported seeing advertisements for cigarettes in media outlets, but anti-tobacco advertising was rare. The majority of young people reported being taught in school about the dangers of smoking. Environmental tobacco smoke exposure was very high in all countries. These results show that the GYTS surveillance system is enhancing the capacity of countries to design, implement, and evaluate tobacco prevention and control programmes.
Stereotactic core needle biopsies (SCNBs) are accurate and relatively convenient for the patient; however, the long-term follow-up of benign results has not been reported. All patients between 1993 and 1998 undergoing SCNB at a community-based hospital were entered into a registry. Follow-up was obtained by a retrospective analysis of the charts. Biopsies were performed on 865 lesions. One hundred thirty-one (15%) were malignant, 42 (5%) were suspicious for malignancy, 687 (79%) were benign, and five (1%) were lobular carcinoma in situ. Of the 42 patients with suspicious findings 38 underwent biopsy. Ten were malignant and 28 benign. Of the 687 patients with benign pathology, 377 had follow-up available with a mean length of 1.7 years. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of SCNB for benign lesions in our study are all 100 per cent. Eight lesions were worrisome and await final analysis. Of 687 patients with benign lesions 310 were lost to follow-up. This study suggests that patients with a benign diagnosis should be returned to routine mammography. These data also extend the reported follow-up to 1.7 years and establish an acceptable level of accuracy for SCNB. The lost patients remind us that follow-up is essential despite a benign diagnosis.
BACKGROUND: Because tuberculosis (TB) in children implies recent infection, children serve as sentinels for disease transmission within a community. Despite the significance of diagnosing tuberculosis in children, most cases are diagnosed on clinical evidence rather than laboratory findings. METHODS: We analyzed the demographic and clinical presentation of 156 children with culture proven tuberculosis using Epi-Info Version 6. RESULTS: Although the clinical characteristics of this population were generally consistent with those seen in previous studies, several unexpected results were observed. Boys were overrepresented in the group of very young children (72% < 1 year). Many of the children had coexisting diseases not known to predispose to TB (37%). Cavitation, usually observed in older children, was seen in four children < or = 1 year of age. Few children were homeless or HIV-infected, but many (42%) lived in female-headed households. Of the adult contacts at risk for TB, many (49%) were recent immigrants to the US. Overall 34% of the population was either foreign born or the children of recent immigrants. CONCLUSIONS: This series of 156 culture-positive children provides an understanding of the risk factors and clinical presentation of pediatric tuberculosis. The data emphasize the impact of the child's environment on the risk for tuberculosis.
Reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI) produced by activated macrophages participate in host defense against the facultative intracellular pathogens Mycobacterium tuberculosis and Salmonella typhimurium. To survive within macrophages, such pathogens may have evolved ROI and RNI resistance mechanisms. ROI resistance pathways have been intensively studied. Much less is known about the mechanisms of resistance to RNI. To identify possible RNI resistance genes in M. tuberculosis, a mycobacterial library was expressed in S. typhimurium and subjected to selection by exposure to the NO donor S-nitrosoglutathione (GSNO) in concentrations sufficient to kill the vast majority of nontransformed salmonellae. Among the rare surviving recombinants was a clone expressing noxR3, a novel and previously anonymous M. tuberculosis gene predicted to encode a small, basic protein. Expression of noxR3 protected S. typhimurium not only from GSNO and acidified nitrite but also from H2O2. noxR3 is the third gene cloned from M. tuberculosis that has been shown to protect heterologous cells from both RNI and ROI. This suggests diversity in the repertoire of mechanisms that help pathogens resist the oxidative and nitrosative defenses of the host.
Antepartum plasma hepatitis C virus (HCV) RNA was quantified in 155 mothers coinfected with HCV and human immunodeficiency virus type 1 (HIV-1), and HCV RNA was serially assessed in their infants. Of 155 singleton infants born to HCV antibody-positive mothers, 13 (8.4%) were HCV infected. The risk of HCV infection was 3.2-fold greater in HIV-1-infected infants compared with HIV-1-uninfected infants (17.1% of 41 vs. 5.4% of 112, P = .04). The median concentration of plasma HCV RNA was higher among the 13 mothers with HCV-infected infants (2.0 x 10(6) copies/mL) than among the 142 mothers with HCV-negative infants (3.5 x 10(5) copies/mL; P < .001), and there were no instances of HCV transmission from 40 mothers with HCV RNA concentrations of < 10(5) copies/mL. Women dually infected with HIV-1 and HCV but with little or no detectable HCV RNA should be reassured that the risk of perinatal transmission of HCV is exceedingly low.
Antepartum pneumonia requires prompt evaluation and empiric antimicrobial therapy. The choice of antimicrobial therapy depends on maternal risk factors, symptoms, and clinical presentation. Although laboratory studies such as culture and serology should be obtained, they may not always yield a specific etiologic agent. However, prompt empiric treatment and supportive care should lead to good maternal and fetal outcomes. Similarly, in most cases, proper diagnosis and treatment of TB during pregnancy yield good maternal and fetal outcomes. TB screening is essential for the growing population of individuals with HIV infection and recent immigrants from areas where tuberculosis is endemic.
PURPOSE: To test the hypothesis that diffusion of contrast medium into the intervertebral disk is affected by the integrity of the nucleus pulposus and annulus fibrosus. METHODS: In canine intervertebral disks, defects were made in the annulus fibrosus and nuclear material was removed from the disk with a nucleotome. MR imaging was performed with intravenous contrast medium at 15, 30, 60, and 90 days after the procedure. The diffusion of contrast medium in the intervertebral disk was studied by visual inspection and by measuring changes in signal intensity. The intervertebral disk were classified at each MR study as normal or abnormal on the basis of the signal intensity on T2-weighted images. RESULTS: In untreated disks after intravenous injection of contrast medium, a band of increased signal intensity was observed near the endplates that became wider with time and approached the center of the disk. In six of the 12 treated disks, the band of increased signal intensity was visibly diminished or less discrete compared with that in the control disks. Weeks later, these treated disks showed diminished signal intensity on T2-weighted images and bulging of the annulus fibrosus. CONCLUSIONS: Intervertebral disks with defects in the annulus fibrosus and reduced cartilage content were characterized by abnormal diffusion of contrast medium into the disk, and changes characteristic of early disk degeneration were detected subsequently.
Cadmium chloride-induced DNA damage was investigated in individual brain, kidney and liver cells isolated from rats gavaged 14 mg/kg/day cadmium chloride. Animals were sacrificed on days 2, 4, 8, 16, and 33, and DNA damage was determined using the recently developed alkaline microgel electrophoresis technique. Data for DNA migration from 50 randomly selected cells clearly show significant increases in DNA damage in cells from three different organs of cadmium chloride gavaged animals compared to saline treated control animals (33 day control, brain 64.7 +/- 5.3, kidney 75.5 +/- 9.4, liver 67.9 +/- 5.7 microm; 33 days experimental, brain 284.3 +/- 16.9, kidney 397.9 +/- 11.3, liver 315 +/- 22.5 microm; these values represent length of exposure in days and length of DNA migration in micron). There was an increase in DNA damage for all three cell types, with increasing duration of treatment. Cadmium (CdCl2) induced levels of DNA single strand breaks were more pronounced in kidney cells than in cells from the other two organs. Body and organ weights decreased of treated animals were decreased as compared to control. Results of this study indicate a potential of cadmium to be a genotoxic compound.
This paper reports on research commissioned by the English National Board for Nursing, Midwifery and Health Visiting into mentorship and clinical support arrangements for Project 2000 nursing students in the adult and mental health branches. Interviews and observation data were gathered from staff and students in three of the demonstration centres. Findings showed that the terms 'mentorship', 'assessor' and 'supervisor' were used interchangeably and covered diverse roles in both clinical and community settings. Generally there was an impression that staff were willing to help students learn from their experience but felt unprepared for the 'new nursing students'. Several factors emerged which seemed either to promote satisfactory experiences for students or inhibit their learning and enjoyment of the placement. These are discussed under the themes 'supernumerary status', 'team spirit', 'theory and practice', 'diploma level practice' and 'organization of nursing teams'.
Data from asbestos workers were used to devise a cutpoint classifier to identify subjects as Nonuser (non-tobacco user), Smokeless (exclusive smokeless tobacco user), and Smoker (ignited tobacco user). In some clinical trials and smoking cessation programs, Smokeless should be separated from Smoker. One therefore needs a marker for smoke exposure, such as thiocyanate, since nicotine levels, as measured by cotinine, could be similar in both groups. Levels of cotinine (ng/mL) and thiocyanate (mumol/L) levels (mean +/- SD) were, respectively: 320.9 +/- 201.1 and 145.9 +/- 63.7 for the Smoker group; 339.1 +/- 327.5 and 32.0 +/- 16.9 for the Smokeless group; and 0.6 +/- 2.6 and 58.2 +/- 33.2 for the Nonuser group. For Nonuser, Smokeless, and Smoker, respectively, the self-reported status was 45.1%, 10.8%, and 44.1%, which was adjusted to 42.2%, 11.6%, and 46.2%; the classifier yielded sensitivities of 100%, 76.1%, and 92.2%; specificities of 96.1%, 97.6%, and 96.4%; and predictive values of 94.9%, 80.6%, and 95.6%. The classifier successfully identified Nonusers, separated Smokeless from Smoker, and determined the prevalence of false reports in our cohort.
A resurgence of tuberculosis has occurred in recent years in the United States and abroad. Deteriorating public health services, increasing numbers of immigrants from countries of endemicity, and coinfection with the human immunodeficiency virus (HIV) have contributed to the rise in the number of cases diagnosed in the United States. Outbreaks of resistant tuberculosis, which responds poorly to therapy, have occurred in hospitals and other settings, affecting patients and health care workers. This review covers the pathogenesis, epidemiology, clinical presentation, laboratory diagnosis, and treatment of Mycobacterium tuberculosis infection and disease. In addition, public health and hospital infection control strategies are detailed. Newer approaches to epidemiologic investigation, including use of restriction fragment length polymorphism analysis, are discussed. Detailed consideration of the interaction between HIV infection and tuberculosis is given. We also review the latest techniques in laboratory evaluation, including the radiometric culture system, DNA probes, and PCR. Current recommendations for therapy of tuberculosis, including multidrug-resistant tuberculosis, are given. Finally, the special problem of prophylaxis of persons exposed to multidrug-resistant tuberculosis is considered.