Pamela Orr

Transfusion-associated Trypanosoma cruzi infection in a non-endemic area.

Excerpt Opportunistic infections have become a major cause of morbidity in the immunocompromised host. In patients with neutropenia, such infections often arise from their own indigenous flora; how...

Febrile urinary infection in the institutionalized elderly

PURPOSE Bacteriuria is common among institutionalized elderly populations, but the contribution of urinary infection to febrile morbidity is unknown because of difficulties in clinical ascertainment. This study was undertaken to febrile morbidity using both clinical and serologic criteria. METHODS Episodes of fever in residents of two long-term care institutions were identified prospectively for 2 years. Serum and urine specimens were obtained initially and at 4 weeks. The proportion of episodes attributable to urinary infection was determined by both standard clinical criteria proposed for use in these populations and serum antibody response to uropathogens. RESULTS For 372 fewer episodes, 211 met clinical criteria for infection: 147 (40%) of the respiratory tract; 26 (7%) of the genitourinary tract; 25 (6%) of the gastrointestinal tract; and 13 (3%) of skin and soft tissue. Of the remaining 161 fever episodes, 2 (1%) were noninfectious and 159 (43%) were of unknown origin. The prevalence of bacteriuria for residents with nongenitourinary sources of fever varied from 32% to 75%. An antibody response meeting serologic criteria for urinary infection occurred in 26 (8.3%) of 314 episodes with paired sera obtained; 10 (43%) of 23 identified clinically as genitourinary infection, 14 (11%) of 132 unknown, 1 (4%) of 25 gastrointestinal, and 1 (0.8%) of 122 respiratory. The positive predictive value of bacteriuria for febrile urinary infection identified by clinical criteria was was 11% (95% confidence interval [CI] 4%, 18%) and identified by serologic criteria was 12% (95% CI 7%, 17%). CONCLUSIONS Urinary infection contributes to less than 10% of episodes of clinically significant fever in this high-prevalence bacteriuric population. A restrictive clinical definition for genitourinary infection has poor sensitivity and specificity compared with serologic criteria for identification of fever of urinary source, and bacteriuria has a low predictive value for identifying febrile urinary infection.

Helicobacter pylori in the Canadian arctic : Seroprevalence and detection in community water samples

OBJECTIVES:Many North American arctic communities are characterized by risk markers associated with Helicobacter pylori (H. pylori) infection, including overcrowded housing and inadequate water supply and sanitation systems. Our aim was to determine the seroprevalence of H. pylori infection in two traditional Inuit communities in the central Canadian arctic and to test for the presence of H. pylori, by polymerase chain reaction (PCR), in local water supplies.METHODS:Samples of venous whole blood from adults and capillary blood from children were collected and analyzed by enzyme immunoassay and Helisal Rapid Test, respectively, for IgG antibody to H. pylori. Antibodies to CagA were detected by enzyme immunoassay, and ABO and Lewis antigens were also determined. Demographic and clinical information were collected by questionnaire. Water samples from each community were tested for H. pylori by PCR.RESULTS:One hundred-thirty (50.8%) of 256 subjects from the two communities were positive for H. pylori IgG antibodies. Seropositive subjects were more likely to be male, compared with seronegative individuals (p= 0.01). Antibody status did not differ with respect to age, community, alcohol or cigarette use, number of persons per household, gastrointestinal complaints or previous investigations, medications, or presence of blood group O, Lewis a−b+. CagA antibodies were detected in 78 (61.9%) of 126 H. pylori-seropositive subjects tested; however, 41 (35.3%) of 116 H. pylori-seronegative subjects were also CagA positive. Water samples taken from the water delivery truck in Chesterfield Inlet and two lakes near Repulse Bay were positive for H. pylori.CONCLUSION:The seroprevalence of H. pylori in the study group was higher than rates in southern Canadian populations, but lower than the seroprevalence previously documented in a Canadian subarctic Indian (First Nations) community. The detection of H. pylori in local water supplies may indicate a natural reservoir for the organism or possible contamination from human sewage.

Functional Gene Polymorphisms in Canadian Aboriginal Populations with High Rates of Tuberculosis

The present study determined whether a pattern of functional single-nucleotide polymorphisms (SNPs) was present that could predispose a Dené cohort to a suboptimal response to Mycobacterium tuberculosis. Compared with a Caucasian cohort, the Dené and Cree were found to maintain a significantly higher frequency of SNPs associated with low expression of vitamin D receptor (VDR), interferon (IFN)-gamma (+874), and tumor necrosis factor-alpha (-308) and high production of monocyte chemoattractant protein (MCP)-1 (-2518) and interleukin (IL)-6 (-174). Given the roles played by IFN-gamma and VDR in facilitating macrophage containment of M. tuberculosis and the opposing role of MCP-1 and IL-6, the observed allelic variation by ethnicity may in part contribute to the high rates of tuberculosis among the Dené.

An outbreak of diarrhea due to verotoxin-producing Escherichia coli in the Canadian Northwest Territories.

In the summer of 1991 a large outbreak of Escherichia coli O157:H7 associated diarrhea occurred in 6 Inuit communities in the Canadian Northwest Territories. The total population of these communities is 5,292. Of the 521 individuals who developed diarrhea, 152 (29%) were positive for E. coli O157:H7 on stool culture or positive by verotoxin analysis. Median age was 6 years. The attack rate for children < 1 year was 43% in the major affected community of Arviat. Hemolytic-uremic syndrome (HUS) developed in 22 cases, and 2 patients died. Asymptomatic stool carriage of verotoxin-producing E. coli (VTEC) 2-5 weeks after diarrheal illness was noted in 4/28 persons followed prospectively. Epidemic curves, case-control studies and phage type testing suggested person-to-person transmission. The original source of infection was not identified, though a food source was suspected. VTEC were detected in 6 food samples (minced beef and caribou) taken from retail outlets and homes. Primary prevention of infection through health education and promotion activities, as well as long-term follow-up of HUS survivors, are indicated in this population.

Seroprevalence of Helicobacter pylori, Incidence of Gastric Cancer, and Peptic Ulcer-Associated Hospitalizations in a Canadian Indian Population

The living conditions of many aboriginalcommunities in Canada may place their residents at riskfor H. pylori infection. Our aims were to determine: (1)the seroprevalence of H. pylori in a traditional Indian community, (2) the clinical relevance ofH. pylori infection in this population, and (3) if H.pylori could be identified by polymerase chain reactionfrom the local water. A demographic questionnaire was administered, and blood was collected fromsubjects in an Indian community in northwesternManitoba. The serum was analyzed by ELISA for IgG to H.pylori and to CagA. ABO and Lewis antigens were tested. Age-adjusted incidence of gastric cancer and ofhospitalizations associated with diagnoses of pepticulcer were determined for the Indian and non-IndianManitoba population in the years 1989-1993. Nested PCR was performed on lake water using H.pylori-specific primers and the amplicons probed with aninternal Dig-labeled probe. Three hundred six (59%) ofapproximately 518 individuals who were resident in the community at the time of the study wereenrolled. The ELISA for H. pylori was positive in 291(95%). There was no association between H. pyloriseropositivity and age, sex, gastrointestinalcomplaints, medications, housing characteristics, and ABOor Lewis antigen status. CagA was positive in 84.5% ofinfected subjects. The average annual age-adjustedincidence of hospitalizations associated with diagnoses of peptic ulcer disease in Manitoba was higherfor treaty-status Indians (394.3/100,000) than fornon-Indians (203.8/100,000), but gastric cancer rateswere similar (11.2/100,000 vs 11.6/ 100,000). No H. pylori DNA was detected in the lake water. Inconclusion, the seroprevalence of CagA-positive H.pylori is high in this representative Manitoban Indiancommunity. This may be associated with an increased risk for peptic ulcer disease but is notassociated with an increased risk for gastriccancer.

Evaluation of 24 locus MIRU-VNTR genotyping of Mycobacterium tuberculosis isolates in Canada

The current gold standard for Mycobacterium tuberculosis complex (MTBC) genotyping is insertion sequence (IS) 6110 restriction fragment length polymorphism (RFLP) as it provides the highest discriminatory power of all available MTBC genotyping methods. However, RFLP is labour intensive and the interpretation of data from this method can be susceptible to errors. In 2001 a rapid, reproducible variable number of tandem repeat (VNTR) based typing method using 12 mycobacterial interspersed repetitive units (MIRU) was developed. Despite this advancement, this method lacked the discriminatory power of IS6110-RFLP. More recently a set of 24 MIRU-VNTR loci was reported to have greater discriminatory power than the original 12 locus system and may exceed that of RFLP when combined with spoligotyping. We compared the 24 locus method to the 12 locus method in order to improve surveillance of tuberculosis in Canada. A random sample of 650 MTBC isolates from British Columbia, Saskatchewan, Manitoba and Quebec Canada was genotyped using the 24 MIRU loci. Comparison of the data for the 12 and 24 MIRU loci showed an increase of the Hunter-Gaston discriminatory index (HGDI) from 0.895 (12 loci) to 0.920 (24 loci). The implementation of the 24 locus MIRU-VNTR methods offers improvement in discriminatory power over the traditional 12 locus method. For long-term surveillance of MTBC within Canada, the use of 24 MIRU-VNTR loci will provide rapid, highly discriminatory molecular epidemiology information.

Urinary Immunoreactive Interleukin-1α and Interleukin-6 in Bacteriuric Institutionalized Elderly Subjects

Urinary immunoreactive interleukin-1 alpha and interleukin-6 levels were measured in specimens obtained from elderly institutionalized subjects, including 67 asymptomatic subjects (51 of whom were bacteriuric), 34 with fever from nonurinary sources, 15 with bacteriuria and 9 with symptomatic urinary infection. For bacteriuric subjects urinary interleukin-1 alpha and interleukin-6 levels were measurable in 18 (35%) and 22 (43%) asymptomatic subjects, respectively, 9 (60%) and 8 (53%) with nonurinary sources of fever, respectively, and 6 (67%) and 7 (78%) with urinary infection, respectively. For subjects without bacteriuria 1 of 16 (6.3%) who were asymptomatic and 5 (25%) with nonurinary sources of fever had measurable urinary interleukin-1 alpha, and 2 (13%) and 1 (5.3%), respectively, had measurable interleukin-6. Presence of interleukin-1 alpha or interleukin-6 was significantly associated with bacteriuria for asymptomatic and symptomatic subjects. Interleukin-1 alpha or interleukin-6 quantitative levels were lower in subjects without than with bacteriuria. Quantitative levels of interleukin-6 tended to decrease for bacteriuric subjects with symptomatic infection between acute and convalescent specimens. These observations suggest that interleukin-1 alpha and interleukin-6 are produced in association with bacteriuria in some elderly subjects. Variation in local cytokine production with time and the clinical significance of these observations require further study.

Nosocomial pneumonia on general medical and surgical wards in a tertiary-care hospital

OBJECTIVE To describe the demographic, clinical, and microbiologic characteristics of patients who develop nosocomial pneumonia on general medical and surgical wards of a tertiary-care hospital. DESIGN A 1-year, prospective, descriptive study. SETTING A 1,100-bed, tertiary-care, urban hospital. POPULATION Patients experiencing nosocomial pneumonia were identified through surveillance on general medical and surgical wards, using a standard case definition. RESULTS 92 pneumonias in 85 patients on general wards were identified. The mean age of patients was 63 +/- 17 years, 55 patients (65%) were male, and 75 cases of pneumonia (81%) were acquired on surgical wards. Bacteremia was identified in 8 (13%) of 62 episodes, and 48 (52%) grew potential pathogens from respiratory specimens. Twenty-six patients (28%) required transfer to the intensive-care unit (ICU), and 20 (22%) received mechanical ventilation. By multivariate analysis, patients with a thoracic surgical procedure or with Staphylococcus aureus isolated from respiratory secretions were more likely to require ICU admission. The overall mortality rate was 20% (17/85), with a directly associated mortality of 14% (12/85). Patients who died were older, more frequently resided on a medical ward, and had a greater mean number of comorbidities. These patients often were treated nonaggressively and were not considered candidates for ICU admission due to advanced age and poor underlying clinical status. CONCLUSIONS Although the morbidity of nosocomial pneumonia in this population was high, as evidenced by high rates of transfer to ICU, the directly associated mortality was relatively low. Those requiring ICU admission require further study to identify preventive measures that could decrease the morbidity in this group. Interventions to prevent pneumonia or to improve prognosis may not be feasible for the majority of these patients who die from nosocomial pneumonia.

Risk factors for infection in women undergoing testing for Chlamydia trachomatis and Neisseria gonorrhoeae in Manitoba, Canada.

Background and Objectives: Despite sharing common modes of transmission, characteristics of individuals infected with Chlamydia trachomatis differ in several respects from those with Neisseria gonorrhoeae infection. Further characterization of women at high risk for chlamydial infection is needed to deliver appropriate and effective preventive, diagnostic, and therapeutic care to this population. Goal of this Study: The demographic and socioeconomic characteristics of women with laboratory confirmed chlamydia, gonorrhea, or coinfection were compared with those of control women who tested negative for both pathogens. Study Design: A random sample of 400 women in Manitoba, Canada, who had undergone testing for sexually transmitted diseases at a public health laboratory in 1988 were studied. After linkage with medical insurance and census databases, logistic regression analysis was used to compare age, ethnicity, urban status, and mean income (using postal codes) of women with gonorrhea alone, chlamydia alone, and coinfection, with the same data for women who tested negative for both organisms. Results: Young age, North American Indian status, urban residence, and low mean income according to postal code were significantly associated with gonococcal and chlamydial infection in the study population, compared with women who tested negative for both infections. Young age, Indian status, and urban residence also were associated with gonorrhea infection alone. Only young age and Indian status were associated with chlamydial infection. Mean incomes of women with chlamydial infection alone and control subjects were higher than those of women with gonorrhea and gonorrhea and chlamydia coinfection. Conclusions: Differences in the demographic and socioeconomic characteristics of women with gonorrhea, chlamydia, and coinfection suggest the existence of multiple reservoirs of infection due to these agents in the study population. The preventive, diagnostic, and therapeutic strategies of sexually transmitted disease control programs must be adapted to the individual needs of identified high-risk groups.