Biomedical subjects
Publications and source records attributed to J L Isaac-Renton.
A system of tangential-flow filtration was evaluated for use in the detection of Giardia cysts in drinking water. This method was more sensitive in recovering cysts than a frequently used wound-orlon system of through-filtration.
A survey was done of Canadians who had been interned by the Japanese during World War II to assess the prevalence of latent infection with Strongyloides stercoralis in this group. Packages containing three mail-in kits and a questionnaire were sent to 992 men, 694 (70%) of whom responded. Larvae were found in the stool specimens of four of the respondents. Examination of stool specimens after formalin-ether concentration was the most successful method of detecting Strongyloides larvae. The Baermann concentration technique yielded negative results in all four men. Three of the four cases of strongyloidiasis were detected after sampling of three fecal specimens. In the fourth case additional specimens were requested on the basis of data derived from the questionnaire. The most frequently cited clinical manifestations were abdominal pain, weight loss, diarrhea and rashes.
It has been suggested that the incidence of infection with mycobacteria other than typical tubercle (MOTT) bacilli is increasing. Laboratory and epidemiologic information relating to MOTT infection in British Columbia between 1972 and 1981 was analysed. Patient records for 1960-81 were also analysed. Of the 313 661 laboratory specimens 13 474 yielded Mycobacterium tuberculosis isolates and 3172, MOTT isolates. Over the 10 years the number of M. tuberculosis isolates declined, whereas the absolute and relative numbers of MOTT isolates increased. Members of the highly drug-resistant MAIS complex (M. avium-intracellulare, M. scrofulaceum and M. simiae) accounted for 73.3% of the 1778 potentially pathogenic MOTT isolates. MAIS isolation rates varied geographically. Analysis of patient records revealed 217 MOTT infections, of which 152 (70%) were due to MAIS organisms. Further studies are needed to determine the source of MAIS organisms in order that the infection and the disease may be more clearly understood.
Using microscopic screening criteria employed in the study of sputum in acute bacterial pneumonia, the authors evaluated 644 sputum samples from 347 patients submitted for mycobacterial bacterial culture. After microscopic examination, these specimens were processed using standard mycobacterial laboratory technics. Salivary specimens accounted for 67.1% of the samples evaluated, and yielded 13 of the total 42 Mycobacterium tuberculosis isolates, as well as 4 of the 21 smear-positive culture-positive specimens. Although specimens from the lower respiratory tract are preferred, specimens of a salivary nature should not be discarded by the Mycobacteriology Laboratory.
Drug resistance has been well documented in two species of malarial parasites. Of greatest concern are the rapid developments in the resistance of Plasmodium falciparum to commonly used therapeutic and chemoprophylactic agents. This species, which is capable of producing life-threatening disease, has shown various levels of resistance in different parts of the world. Also, some strains of the most common species causing relapsing disease, P. vivax, exhibit resistance to primaquine. Three cases of malaria that demonstrate various types of drug resistance are presented in this paper.
In a comparative study of the inhibitory and lethal effects of rosaramicin, erythromycin, and clindamycin on strains of Campylobacter fetus subsp jejuni and C intestinalis, C jejuni was more readily killed by rosaramicin and clindamycin than was C intestinalis. Erythromycin exhibited an equally lethal effect against both subspecies. However, it was the least active of the macrolides tested against both C jejuni and C intestinalis.
Staphylococcus saprophyticus biotype 3 (Micrococcus subgroup 3 or M3) has usually been shown to be the second commonset cause of urinary tract infections in European women who are not in hospital. It generally causes pyuria and symptoms as severe as those caused by Escherichia coli. Unlike S. epidermidis it is seldom found as a contaminant in midstream urine specimens, and almost exclusively infects women in their reproductive years. However, S. saprophyticus is seldom differentiated from S. epidermidis in Canadian clinical laboratories. Urinary isolates of S. saprophyticus were presumptively differentiated from other coagulase-negative Micrococcaceae by their resistance to novobiocin as demonstrated by a simple disc susceptibility test that misidentified the infecting organism in only 3.4% of specimens. These novobiocin-resistant, coagulase-negative organisms caused similar proportions of the urinary tract infections in young women in York, England and Vancouver -- 6.6% and 6.9% respectively. In York these organisms were associated with significantly greater pyuria than novobiocin-sensitive organisms or bile-tolerant streptococci but not S. aureus or Enterobacteriaceae. In both communities novobiocin-sensitive, coagulase-negative Micrococcaceae were appreciably more resistant to penicillin than novobiocin-resistant organisms. Thus, differentiating S. saprophyticus from novobiocin-sensitive, coagulase-negative organisms provides information that is clinically useful, particularly for primary care practitioners working in the community or in outpatient clinics.
This report describes the case of a patient with chronic lymphocytic leukemia in whom septicemia caused by a nontoxigenic strain of Corynebacterium diphtheriae developed. Numerous abscesses were present in sections of liver and spleen taken at autopsy. The case is discussed, and the literature on infections caused by organisms of the genus Corynebacterium is briefly reviewed.
A waterborne outbreak of giardiasis which occurred 5 years after another in the same town in Canada was investigated. Sera from residents defined as cases or non-cases were tested by enzyme-linked immunosorbent assay (ELISA) and compared with sera from symptomatic and asymptomatic control groups. The outbreak-associated Giardia isolate was retrieved from contaminated drinking water and antigen from this strain was used in the serological investigation. Up to 84% of cases were identified by ELISA. More cases were identified by elevated immunoglobulin (Ig) G than by either elevated anti-Giardia IgA or IgM levels. Residents of the community infected during the first outbreak were significantly less likely to have been reinfected during the second outbreak. This is the first report of a second waterborne outbreak occurring in a community and results of the investigations are consistent with an acquired, protective immunity lasting at least 5 years.
Giardia is the most frequently reported intestinal parasite in Canada. More than 2,000 cases are reported annually in British Columbia which exceeds the number of cases of either campylobacteriosis or salmonellosis. Since the different ways this parasite is spread in British Columbia have not been determined, our purpose was to investigate certain factors that might be associated with acquiring giardiasis in this province. Telephone interviews provided information from a group of infected persons and from a group of non-infected control subjects. Information obtained from these interviews was used to identify associated risk factors in this group of cases. If results of the study are generalized to the population-at-risk, they indicate that water (drinking and recreational) is an important vector for transmission of Giardia in British Columbia.
The epidemiology and clinical presentations of giardiasis are reviewed to provide a basis of understanding the laboratory aspects of this parasitic infection. Diagnosis is then discussed in light of recent studies that challenge our overall approach to the diagnosis of enteric parasites and demonstrate the need for further evaluation on the basis of cost-effectiveness as well as reliability and clinical practicality. Overall effectiveness as well as the difficulties with present standard diagnostic methods in giardiasis are reviewed. This is followed by a discussion of the more recently developed immunological approaches to diagnosis. The role of these tests in the parasitology laboratory is also discussed.
Explore the source record for details and available documents.
Explore the source record for details and available documents.