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M Isaäcson

Publications and source records attributed to M Isaäcson.

At least 37 records · Page 2Linked to original sources
PubMed1986

Application of enzyme immunoassays for the confirmation of clinically suspect plague in Namibia, 1982.

An outbreak of plague occurred in Ovamboland, northern Namibia, late in 1982. Blood cultures, sera and blood clots were tested to obtain laboratory confirmations for clinically suspect cases of the disease. Isolation of the bacillus (Yersinia pestis) was attempted from blood cultures; sera were tested for antibody by passive haemagglutination (PHA) and enzyme-linked immunosorbent assay (ELISA). Sera and clots also were tested by ELISA for the specific F1 plague antigen. All the ELISA procedures were based on a monoclonal antibody to F1 antigen to ensure specificity.Thirty-eight cases were confirmed as plague: 50% by isolation, 34% by antibody responses, and 16% by the detection of antigenaemia. All isolates of Y. pestis were capable of producing F1 antigen, and significant antibody responses were observed in bacteriologically confirmed cases with paired sera. Patients who experienced sero-conversion had a higher IgM titre than IgG titre during the first nine days of hospitalization, while patients hospitalized for 17 or more days had IgG titres that were higher than the IgM titres. The relationship between IgM and IgG antibody titres is discussed with reference to identifying very recent infections. PHA titres increased and declined with IgM titres but were lower and more transient.ELISA procedures increased laboratory confirmations of plague by 23% above the numbers achieved using blood cultures and PHA tests alone. The ELISA to detect F1 antigen accounted for 86% of this increase by confirming cases where bacteriological isolation was not done. This ELISA did not replace the requirement for bacteriological isolation, since seven bacteraemic patients did not demonstrate antigenaemia.

Adolescent↗
PubMed1985

In vivo and in vitro chloroquine-resistant falciparum malaria in Venda. A case report.

A Venda child with Plasmodium falciparum malaria had a recurrence of illness 3 weeks after an adequate course of chloroquine. She was treated again with chloroquine and improved clinically but had persistent asexual parasitaemia during the 9 days after completion of the second course of treatment. At this stage chloroquine-resistant malaria was suspected but she was treated again with chloroquine in higher dosage, as alternative antimalarial drugs were not available locally. The patient recovered clinically, her parasitaemia cleared, and she showed no side-effects. Although not routinely recommended, a higher dose of chloroquine may be a useful option when alternative antimalarial drugs are not readily available. Chloroquine resistance was confirmed by Rieckmann's in vitro method, which showed complete inhibition of schizont development in the presence of 16 pmol chloroquine base per well instead of 6 pmol or less as seen with sensitive strains. This case is the first reported of proven chloroquine-resistant malaria acquired in the RSA. This single case does not indicate the existence of a drug-resistant malaria problem in the RSA but points to a need for clinical vigilance and for appropriate surveillance.

Child↗
PubMed1985

A note on an antimicrobial agent in disc paper and a modified assay procedure for detecting antimicrobials in milk.

Commercially available disc paper used for antibiotic sensitivity tests was shown to contain an unidentified, water-soluble agent inhibitory to Bacillus stearothermophilus which gave false positive results in an antimicrobial assay for milk. The agent however, was found to be inactive against a range of common pathogenic bacteria. It was easily removed by washing the discs in distilled water before use.

Animals↗
PubMed1985

In vitro and in vivo cholera toxin production by classical and El Tor isolates of Vibrio cholerae.

A comparative study was carried out on the in vitro production of cholera toxin by 19 Vibrio cholerae El Tor isolates from patients with cholera in South Africa, one El Tor isolate from a patient in Malawi (a country approximately 1000 km north-northeast of South Africa), 6 El Tor and 12 classical type isolates from patients in Bangladesh, and 5 culture collection classical strains. Identical phage types and indistinguishable toxigenicities among the South African and Malawi V. cholerae, representing isolations obtained over a 10-year period, indicated that essentially a single strain was involved in the cholera of these regions. Similarly, phage typing and toxin profiles indicated that the 12 classical and 6 El Tor V. cholerae cultures in Bangladesh, all isolated in November 1983, represented just two strains. As assessed by titrations in Y-1 mouse adrenal and Chinese hamster ovary cell lines, the general order of toxigenicities was Bangladesh and culture collection classical greater than Bangladesh El Tor greater than southern African El Tor. The African isolates consistently gave rise to very low titers. Their relative reluctance to produce the toxin in vitro compared with the culture collection classical strains, particularly strain 569B, was confirmed by rocket electrophoresis. In somewhat of a contrast, maximum in vivo titers in rice water stools from cholera patients in South Africa and from both classical and El Tor type cholera patients in Bangladesh were essentially equal. It is postulated that under the continuous culture conditions that occur in vivo, cholera toxin concentrations can accumulate to a maximum level, depending on the rate of purging by the diarrheal fluid rather than the toxigenicity of the infecting stain. The relevance of these findings to the relative severities of classical and El Tor types of cholera is discussed.

Bangladesh↗
PubMed1984

Probable chloroquine-resistant Plasmodium falciparum malaria in south-western Africa.

Chloroquine-resistant Plasmodium falciparum malaria has been described in East, Central and West Africa. We report on 2 patients with probable chloroquine-resistant P. falciparum malaria in south-western Africa. Both patients had been in northern SWA/Namibia and southern Angola, but had taken prophylactic chloroquine. Despite the subsequent administration of adequate courses of chloroquine therapy, the parasitaemias failed to clear completely. Eventual clinical and laboratory-proven cure was only obtained in 1 case after combined quinine and tetracycline therapy. To our knowledge, these represent the first cases of probable chloroquine-resistant P. falciparum malaria acquired in this area.

Adult↗
PubMed1983

Vibrio cholerae bacteraemia in a newborn infant. A case report.

A 6-day-old Black male infant presented with diarrhoea and biochemical evidence of severe electrolyte imbalance. Despite treatment with intravenous fluids and antibiotics, he died within 24 hours of admission. Enterotoxigenic Vibrio cholerae, biotype E1 Tor, serotype Inaba, was isolated from the blood. The significance of this finding is discussed.

Humans↗
PubMed1983

Ecology of plague in Africa: response of indigenous wild rodents to experimental plague infection.

The Mastomys natalensis species complex, subdivided into genetically distinct species having diploid chromosome numbers 2n = 32 and 2n = 36, is a reservoir for several zoonoses including Lassa fever and plague. This report describes a study to determine whether these sibling species and three other rodent species have different potential as reservoirs for plague. It was found that M. natalensis (2n = 32) was significantly more resistant to experimental plague infection (50% survived inoculation with 120 000 Yersinia pseudotuberculosis subsp. pestis) than was M. coucha (2n = 36) (none of which survived doses of 190 Y. pseudotuberculosis subsp.pestis). In descending order of resistance were M. natalensis, Aethomys chrysophilus, M. coucha, Tatera leucogaster and A. namaquensis. No A. namaquensis survived inoculation of 10 or more plague bacilli.Previous reports on susceptibility to plague or other infections, which were based exclusively on findings in the universally distributed laboratory-bred Mastomys, are thus not necessarily applicable to the M. natalensis species as a whole but probably only to M. coucha. The Y. pseudotuberculosis subsp. pestis fraction-1 passive haemagglutination test appeared to be relatively insensitive in that only 5 out of 47 animals surviving experimental plague infection showed specific antibodies 6 weeks after challenge.The geographic distribution of human plague in southern Africa corresponds closely with that of the plague-susceptible species, M. coucha, while the resistant species, M. natalensis, predominates in areas where human plague has not been recorded. The role of A. namaquensis in the ecology of plague needs to be carefully studied and its possible importance in plague research should be investigated further.

Africa↗
PubMed1978

Emergence of multiply resistant pneumococci.

Multiple antimicrobial resistance in pneumococci was detected in Johannesburg in July, 1977, and prompted an investigation of the prevalence of resistant strains in two hospitals. Carriers of Types 6A and 19A penicillin-resistant pneumococci, resistant to antibiotic concentrations ranging between 0.12 and 4 microgram per milliliter were found in 29 per cent of 543 pediatric patients and 2 per cent of 434 hospital staff members. Multiply resistant Type 19A strains, resistant to beta-lactam antibiotics, erythromycin, clindamycin, tetracycline and chloramphenicol, were isolated from 128 carriers, and were responsible for bacteremia in four patients. Isolates from 40 other carriers were resistant to penicillin alone or to penicillin and chloramphenicol or to penicillin, chloramphenicol and tetracycline. Pneumococci can be screened for penicillin resistance with a modified Kirby--Bauer technic; the strains with zones of less than 35 mm around 6-microgram penicillin disks or less than 25 mm around 5-microgram methicillin disks should be tested for sensitivity to penicillin by measurements of minimum inhibitory concentration.

Adult↗
PubMed1978

Handling of highly infectious material in a clinical pathology laboratory and in a viral diagnostic unit.

The handling of potentially lethal and highly infective material in a routine clinical pathology laboratory and in a viral diagnostic unit is detailed. Extensive precautions were taken at each step of the receiving, processing and disposal cycle. Disposable protective clothing and apparatus were used whenever possible. Laboratory tests were limited to those essential for the clinical management and diagnosis. Technologists who handled infective material were limited to minimal numbers of experienced, non-pregnant, informed volunteers. They wore special protective clothing, including gloves, caps, gowns and masks. When possible, specimens were handled under special protective hoods. Potentially infective material was processed through automated apparatus, and care was taken to prevent contamination of its exterior. The effluent from the machines was collected into viricidal agents (glutaraldehyde, sodium hypochlorite). After processing, the machines were flushed extensively with viricidal solution. This procedure has caused no damage to the automated equipment and has been adopted as a routine laboratory safety measure. The protective procedures adopted were successful in that there was no outbreak of the viral infection among the associated laboratory workers.

Animals↗
PubMed1978

Wild rodents as laboratory models and their part in the study of diseases.

The paper describes the use of 14 South African wild rodent species as experimental models and demonstrates the proven value of many of these as laboratory animals in research on bacterial infections (plague, relapsing fever), rickettsial infections (tickbite fever, louse typhus), viral infections (poliomyelitis. Rift-Valley fever and other arbovirus infections, Lassa fever), fungal infections (histoplasmosis), parasitic infections (schistosomiasis) and in diabetes mellitus and cancer research.

Animal Husbandry↗